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수지유동 해석을 통한 액상성형공정 적용 항공기 날개보 구조물의 함침특성 평가
No full textVacuum- assisted resin transfer molding (VaRTM) is emerging as one of the most robust alternatives for the autoclave process. VaRTM applies the resin infusion method in a vacuum environment. It generally uses reinforcement and a polymer matrix separately in the process. VaRTM is influenced mainly by the characteristics of the constituent materials, such as preform permeability and resin viscosity. Among these, the process design involving the arrangement of the resin inlet/outlet line significantly influences the process performance. Furthermore, an inappropriate inlet/outlet layout cause voids, porosities, or resin-starved areas, which has a decisive effect on quality degradation.
In a typical VaRTM process, the inlet and outlet lines are used as a runner for the resin to flow. Furthermore, an equal length of line is used for uniform infiltration and outflow rate during infusion. In addition, excess resin is infused into the preform to reduce the risk of unsaturated zone after the infusion process. This prolongs the infusion process and results in excessive consumption and wastage of resin.
In this study, a highly curved and twisted winglet spar structure was used as the test specimen. Its complex and asymmetrical shape caused non-uniform impregnation, which results in local unsaturated zone during infusion. Therefore, the adjustment of the inlet/outlet line length was attempted for flow simulation and experiment. The permeability, which is the most critical parameter for flow simulation, was predicted theoretically by incorporating an experimental constant. Furthermore, it was verified through a comparison with a reference experimental measurement and was used for flow simulation.
In addition, the geometrical ply wrinkle on the outer flange of the spar preform and cross-sectional ply wrinkle on the corner area caused by the local compression load over the preform material were investigated. Local slitting on the 0° layer and the rotated rosette method were experimentally verified and proposed. Moreover, the effect of the draping membrane material on single diaphragm forming was studied experimentally. It was verified that during single diaphragm forming, the draping membrane should have sufficient stiffness and plasticity to maintain a uniform draping pressure and constant rate.
The infusion process for an asymmetrical complex-shaped winglet spar structure was simulated using PAM-RTM software. Nine cases with the adjustment of the inlet/outlet line length proportionally selected were attempted for simulation. The most optimized simulation case of the winglet spar was determined based on the impregnation behavior, injected volume, and lost volume calculated by flow simulation. Furthermore, the simulation results were compared and verified with the results of three actual test part experiments.
There was a good agreement between the simulation and experimental results. The simulation result helped predict the resin impregnation behavior and defect during infusion. It was verified that the unsaturated zone was altered and improved by controlling the resin infiltration rate by adjusting the inlet/outlet line length.
It was verified that the flow simulation could be used effectively to reduce the need for the trial-and-error method in infusion process design and to optimize the infusion process window for full impregnation of preform.1. Introduction 1
1.1. Background 1
1.2. Literature Review 21
1.3. Objective of Study 32
2. Material Characterization 35
2.1. Permeability 35
2.2. Theoretical Calculation 37
2.3. Experimental Method 41
2.4. Experimental Result 46
2.5. Conclusion 54
3. Preform Forming 56
3.1. Wrinkle Mechanism 56
3.2. Experimental Method 63
3.2.1. Forming Trial 1 63
3.2.2. Forming Trial 2 67
3.3. Experimental Result 70
3.3.1. Forming Trial 1 70
3.3.2. Forming Trial 2 72
3.4. Conclusion 79
4. Flow Simulation 81
4.1. Flow simulation 81
4.2. Simulation conditions 86
4.3. Result and Discussion 94
4.4. Conclusion 101
5. Infusion Experiment 102
5.1. Flat Panel Evaluation 102
5.1.1. Experiment 102
5.1.2. Experimental Result and Discussion 107
5.2. Spar Build Test 111
5.2.1. Experiment 111
5.2.2. Experimental Result and Discussion 115
5.3. Conclusion 126
6. Conclusion 128
References 132Docto
택란 잎의 Matrix metalloproteinase 활성 저해 효과 및 항산화 효과
No full textLycopus lucidus Turcz. from Lamiaceae family, is a traditional eastern Asian medicinal plant, which is abundant in natural bioactive flavonoids, coumarins, terpenoids and tannins with potential antioxidant activity. In the present study, L. Turcz. leaves were extracted with acetone/methylene chloride and methanol solution, then sequentially partitioned with solvents (n-Hexane, 85% aqueous methanol, and water) in different polarities. Thus, two crude extracts (A+M and MeOH), as well as resulting four fractions (n-Hex, 85% aq. MeOH, n-BuOH and Water) was prepared to investigate the biological activities of L. Turcz. leaves.
The effect of six samples on H2O2-induced injury in SH-SY5Y human neuroblastoma cells were evaluated by MTT assay at different doses (0.025 mg/L-0.25 mg/L). To study antioxidant effects of the crude extracts and fractions, reactive oxygen species (ROS) on SH-SY5Y human neuroblastoma cells and changes on intracellular glutathione (GSH) production were determined. In addition, nitric oxide (NO) as a mediator involved in the inflammation reaction, the inhibitory effects of NO production from samples were measured by using the in vitro lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophage cell line. Western blotting experiment was performed to compare the expression level of matrix metalloproteinases-2 and -9 (MMP-2 and MMP-9) in the phorbol 12-myristate 13-acetate (PMA)-induced HT-1080 cells. Finally, radical mediated DNA damage in HT-1080 cells were performed to investigate the protection ability from L. lucidus Turcz. leaves on DNA oxidative damage.
In MTT assay, the pretreatment of MeOH extracts and four fractions from L. lucidus Turcz. leaves significantly increased the viability of H2O2 induced SH-SY5Y cells (p<0.05). But there was not any positive effect on SH-SY5Y cell viability after the treatment of A+M sample, which may be explained by the high cytotoxic effect from A+M sample. In western blotting experiment, these extracts and fractions led to a reduction of the secretion levels of MMP-2 and MMP-9 in HT-1080 cells. Due to the cell cytotoxicity of A+M extract, MMP-2 cannot be detected in this group, and only MMP-9 bands were found in control and Water fractions groups. In DNA oxidation analysis, the maximum inhibition of the genomic DNA damage caused by excessive oxidative stress was 80.89%, which is due to the present of A+M extracts.
In antioxidant activity, intracellular ROS generation was significantly attenuated in two cells after treatment of crude extracts and fractions (p<0.05), 85% aq. MeOH and n-BuOH fractions showed a better scavenging ability than others. As for the effect of GSH production, A+M extract showed a more powerful ability in enhancing the GSH production by 15.81% than MeOH extract (13.53%) at the concentration of 1 mg/mL; meanwhile, among the fractions at the concentration of 0.5 mg/mL, 85% aq. MeOH fraction increased the GSH level most by 15.30% and followed by the n-BuOH fraction (11.80%).
In regard to the effect of production of NO in RAW 264.7 cells, groups of treatment with samples all showed a significant decrease of NO level in comparison with control group (p<0.05). Both extracts efficiently decreased the NO production of cells at the inhibition of more than 80%. However, among the fractions, Water and n-Hex fractions showed better inhibitory effects in NO production than those of 85% aq. MeOH and n-BuOH fractions. Results obtained collectively indicate that the good biological activities from L. lucidus Turcz. leaves, which can be exploited for plant based anticancer and antioxidant agents in the pharmaceutical, cosmetic, nutraceutical and food industries.1. Introduction 1
2. Materials and Methods 6
2.1 Plant materials 6
2.2 Crude extractions and solvent fractions from L. lucidus Turcz. leaves 6
2.3 Cell culture 8
2.4 Measurement of SHSY-5Y neuroblastoma cell viability by MTT assay 8
2.5 Measurements of antioxidant activity from L. lucidus Turcz. leaves 9
2.5.1 Measurement of intracellular reactive oxygen species (ROS) 9
2.5.2 Determination of intracellular glutathione (GSH) concentration 9
2.6 Measurement of intracellular nitric oxide (NO) concentration 10
2.7 Measurement of matrix metalloproteinase activity and genomic DNA oxidation 10
2.7.1 HT-1080 fibrosarcoma cells culture 10
2.7.2 Western blotting 10
2.7.3 Genomic DNA isolation and determination of radical mediated DNA damage 11
3. Results and Discussion 12
3.1 Effect of L. lucidus Turcz. leaves on SH-SY5Y neuroblastoma cells under oxidative stress 12
3.2 Antioxidant effects of L. lucidus Turcz. leaves 15
3.2.1 Inhibitory effect of L. lucidus Turcz. leaves on ROS generation in SH-SY5Y neuroblastoma cells 15
3.2.2 Effect of L. lucidus Turcz. leaves on intracellular glutathione (GSH) prodution 20
3.3 Effect of L. lucidus Turcz. leaves on production of nitric oxide (NO) 23
3.4 Effect of L. lucidus Turcz.leaves on matrix metalloproteinase activity and genomic DNA oxidation 26
3.4.1 Effect of L. lucidus Turcz.leaves on matrix metalloproteinase activity 26
3.4.2 Effect of L. lucidus Turcz. leaves on genomic DNA oxidiation 29
4. Summary and Conclusion 32
Reference 34Maste
해사영어 특수코퍼스를 활용한 해사영어 어휘목록 개발
No full textThis research provides an overview of the vocabulary in Maritime English from multiple facets. For this research purpose, the Maritime English Corpus (MEC) was compiled, containing about ten million running words with six sub-corpora. It consists of written data of conventions and regulations, committee resolutions, journal articles, media texts, textbooks, and special genres (charter parties and marine accident investigation reports) in the maritime domain. In order to investigate the vocabulary demands for understanding different types of English written texts in the maritime domain, range analysis was carried out on the sub-corpora in the MEC. The results show that even mastering the BNC/COCA 25,000 word families, learners and prospective users could only reach the vocabulary threshold for minimally acceptable comprehension (95%). However, the lexical coverage percentage of the BNC/COCA 25,000 word families plus proper nouns, marginal words, transparent compounds, and acronyms in none of the sub-corpora (subsets) in the MEC could reach the upper boundary (98%) over which learners are likely to gain an optimal comprehension. From this point of view, it is not hard to infer the fact that mastering high-frequency general words is apparently not enough to understand various Maritime English written texts. In light of the limited research on Maritime English vocabulary and the necessity of meeting vocabulary needs within the maritime domain, the Maritime Academic Word List (MAWL) and the Maritime Technical Word List (MTWL) were developed in the present study.
To generate the MAWL, a corpus of academic texts in maritime disciplines was constructed. The Maritime Journal Articles Corpus (MJAC) contains more than three million running words, including 478 texts of recent ten years English journal articles in the fields of marine policy and management, transportation and logistics, marine structure and engineering, economics and business, navigation, and maritime law. Based on the MJAC, the MAWL was generated by multi-dimensional selection criteria and resulted in a list of 1,684 words (lemmas), which has about 34% lexical coverage in Maritime English academic texts across a wide range of maritime disciplines. Study findings pointed out that the lexical items in the MAWL, as compared to those in the general academic vocabulary lists, are more targeted and discipline-specific. Therefore, the MAWL as an enhancement and supplement to the general academic vocabulary lists could better meet the needs of Maritime English learners and prospective users.
In addition to the vocabulary needs of English for Academic Purposes (EAP), knowledge of technical words in a specialized area is also crucial to one’s development in a professional field. As a result, developing a list of commonly used Maritime English technical words is necessary for English for Specific Purposes (ESP) teaching and learning. Based on the MEC, a list of Maritime English technical vocabulary was developed by adopting a hybrid method combining keyword analysis and technical words rating scale. To enhance the method, both frequency keyword analysis and text dispersion keyword analysis were carried out. The resulting MTWL contains 527 words (types), and a supplementary list of 124 acronyms and proper names crucial to various maritime contexts. The MTWL covers 3.64% tokens in the MEC and the coverage percentage increases to 4.23% if the items in the supplementary list are included.
This study provides a deeper insight into Maritime English as a specialized language in multiple aspects. The results offer valuable information on vocabulary load in different types of Maritime English written texts. And the MAWL and the MTWL are expected to contribute to the rapidly expanding field of discipline-specific vocabulary lists. Furthermore, the findings in this study will also benefit EAP and ESP teaching and learning in several ways.Chapter 1 Introduction 1
1.1 Research background 1
1.2 Research objectives 5
1.3 Significance of the research 6
1.4 Layout of the dissertation 8
Chapter 2 Literature Review 10
2.1 Vocabulary studies 10
2.1.1 Key issues in developing vocabulary lists 10
2.1.2 Previous studies on vocabulary lists 29
2.1.3 Lexical coverage 42
2.2 Maritime English 46
2.2.1 English for Specific Purposes (ESP) 46
2.2.2 Maritime English as ESP 50
2.2.3 Previous studies on Maritime English 51
Chapter 3 Methodology 55
3.1 Corpora employed in the research 55
3.1.1 Maritime English Corpus (MEC) 55
3.1.2 Maritime Journal Articles Corpus (MJAC) 62
3.1.3 Reference corpus 64
3.2 Instruments for data processing 66
3.2.1 AntWordProfiler and BNC/COCA word family lists 66
3.2.2 Stanford CoreNLP 67
3.2.3 WordSmith Tools 67
3.2.4 Technical words checklist 68
3.3 Procedures of data processing 71
3.3.1 Range analysis 71
3.3.2 Extraction of maritime academic words 72
3.3.3 Extraction of maritime technical words 78
Chapter 4 Results and Discussion 84
4.1 Lexical profile of Maritime English 84
4.1.1 Lexical coverage in MEC 84
4.1.2 Lexical coverage in conventions and regulations 87
4.1.3 Lexical coverage in committee resolutions 89
4.1.4 Lexical coverage in journal articles 91
4.1.5 Lexical coverage in media texts 93
4.1.6 Lexical coverage in textbooks 95
4.1.7 Lexical coverage in special genres 97
4.1.8 Lexical coverage of GSL and AWL in MEC 102
4.1.9 Comparison of vocabulary load in MEC sub-corpora 106
4.2 Maritime Academic Word List (MAWL) 109
4.2.1 Coverage of MAWL across corpora 112
4.2.2 Lexical profile of MAWL 114
4.3 Maritime Technical Word List (MTWL) 119
4.4 Comparison between MAWL and MTWL 125
Chapter 5 Conclusions 134
5.1 Major findings 134
5.2 Pedagogical implications 139
5.3 Limitations and suggestions 141
References 143
Appendices 162
Appendix A: Maritime Academic Word List (MAWL) 162
Appendix B: Maritime Technical Word List (MTWL) 179
Appendix C: Supplementary List of MTWL 195Docto
Focusing on comparison of hazardous goods regulations in Korea and China
No full text해양은 지구표면의 약 70%로 차지하며 인류가 무역과 운송을 하는 중요한 통로다. 위험물은 전 세계 컨테이너 운송량의 5%∼10%를 차지하며, 이 중 항만은 대부분의 위험화물과 위험물을 적재한 컨테이너를 처리하고 있다. 중국 연해 항만의 컨테이너 위험물 수출·입량은 세계 상위권을 차지하고 있으며, 2020년을 기준으로 할 때 전 세계 항만 위험물컨테이너 물동량 순위에서 중국 상하이 항이 4,350만 TEU로 1위를 차지하는 등 11년 연속 전 세계 1위를 차지고 있다. 물론 부산항도 2,181만 TEU로 세계 7위를 기록하고 있다.
경제가 빠르게 발전하고 공업의 꾸준한 진보에 따라 각 업종의 위험물에 대한 수요량은 지속적으로 증가하고 있다. 그러나 화학공업 발전은 우리에게 물질적 풍요를 가져다주는 동시에 일정한 위험과 도전을 가져왔다. 특히 위험화물의 운송, 저장 등의 과정에서 관리제도의 비 엄격으로 인하여 많은 항만 사고 등이 발생하였다. 특히 위험화물의 관리 기준 및 시행기준이 명문화되어 있지 못함으로 인해 사고의 규모가 줄어 들지 않고 있으며, 또한 화물 자체의 불안정성과 위해성은 환경피해를 유발하고 생태계를 파괴하며, 나아가 인류의 생존과 발전에 영향을 주고 있다. 따라서 항만 위험물 관리가 부실할 경우 안전사고뿐만 아니라, 환경재난 역시 심각한 문제가 되고 있다. 이러한 이유들로 인해 항만 내 위험물의 안전관리의 중요성은 점점 강조되고 있는 것이다.
2015년 발생한 중국 텐진항 폭발사고는 지금까지 중국에서 발생한 최악의 위험물 안전사고 있다. 이 사고를 통해 중국의 위험물 관리 규정이 미비하고, 감독기관의 관리 부실, 항만 종사자들의 교육 부족 및 반칙 집행 등의 많은 문제점들이 드러났다. 그러나 위험화물 관리에 관한 국제협약 들 특히 "국제해상위험물규칙”, "위험물운송 국제규정" 및 "항만내 포장위험물의 안전운송 및 취급에 관한 권고" 등의 국제기준은 위험물에 대한 정의 분류부터 저장, 취급, 운반 및 안전관리에 관한 규정 등 전면적으로 체계적이며, 효과적으로 규정되어 있다. 또한 해운강국인 한국 역시 "위험물안전관리법", "화학물질관리법" 등 관련 법률 규정을 통해 효과적으로 위험화물 등을 관리하고 있다.
이에 본 연구의 목적은 한·중 양국의 항만내 위험물 안전관리에 관한 법률 비교를 통해 중국의 문제점을 제기하고자 한다. 또한 관련 국제규정 등을 검토해 항만내 위험물 안전관리에 대한 중국의 정책적, 법률적 개선 및 방향을 제시하고자 한다 .
본문은 7장으로 구성되어 있다.
제1장은 본문의 서론이다. 본문의 연구 배경과 의의를 명백히 논술하고 본문의 연구 내용과 방법을 소개하였다.
제2장은 "국제해상위험화물규칙", "국제해양오염방지협약", "화학물질분류 및 표시에 관한 국제규정" 등 국제협약을 중심으로 위험물에 대한 정의와 분류, 항만내 위험물 관리에 대한 중요성과 위험의 특성, 그리고위험화물 처리량 및 위험의 영향 등을 분석하였다.
제3장은 중국의 위험물 관련 법률 규정과 국제 위험물 관련 규정들을 소개하고, IMO의 "항만내 포장위험물의 안전운송 및 취급에 관한 권고(MSC/Circ. 1216)”의 내용, 그리고 미국, 일본, 싱가포르, 네덜란드 등 선진국의 항만내에서의 위험물 관리 규정들을 소개했다.
제4장은 중국의 텐진항 폭발사고에 대해 그 원인과 결과 등을 분석하였다. 텐진항 사고를 통해 중국이 안고 있는 위험물 안전관리에 관한 전체적인 문제점들을 5가지로 분석하였다.
제5장은 한국의 항만위험물 관련 법률 규정에 대해 살펴보았으며, 위험물의 정의와 분류, 항만위험물 감독, 사고 대응과 위험물 운송 및 저장 등 4가지 부분에 대해 한·중 관련 법률을 비교 분석하였다. 이를 통해 중국관련 법률 규정들의 문제점을 도출하였다.
제6장은 제5장에서 분석한 중국 항만내 위험물 관리제도의 문제점을 보완하고자 정책적인 제안과 법률의 개정을 논의하였다. 항만위험물 통합분류, 항만 내 위험물 관리 주 당국 지정, 기업 특화 및 표준화 구축 강화, 사고 예방 역량 강화를 위한 첨단 기술 도입, 항만보안 위험의 명확한 구별과 함께 사고이론을 유연하게 활용, 항만 내 위험물 운영자에 대한 교육 및 평가 제도 개선, 항만내 위험물 안전도 평가체계 개선에 대한 정책적 제안 및 항만 위험물 관리 규정, 중국 항만 내 위험물 운영의 안전성 평가를 위한 지침 개정등을 제안하였다.
제7장은 결론부분으로서 제2장부터 제6장까지 언급된 전반적인 부분과 중국의항만위험물관리의 실태와 문제점, 그리고 이를 보완하기 위한 정책적, 법률적 개정안을 제시하면서 본 논문을 마무리 하였다.The ocean accounts for about 70% of the earth surface and is deemed as important channel for trade transport by mankind. In the global freight volume of container, dangerous goods account for 5%~10%. The port takes charge of transferring the freight container of lots of dangerous goods. The import and export of container dangerous goods on China coastal port rank top in the world. In the ranking of throughput of global port container in 2020, Shanghai Port topped the list with 43.5 million tons (it has ranked top one in the world for continuous eleven years), and the port of Busan in Korea ranked top seven with 21.81 million tons.
With the rapid development of economy and the continuous progress of industry, various industries' demand for dangerous goods has continued to increase. Industrial development also brings certain danger and challenge when we share materials. The loose formulation of management system and irregular execution standard in the process of transport, storage, etc. as well as instability and hazard of dangerous goods cause direct harm to personnel's fitness and easily trigger environmental harm, destroying environment and ecology and further influencing the survival and development of mankind. Therefore, the improper management of dangerous goods at port will cause major safety accident and environmental disaster. The safety management of dangerous goods in port is very important.
In 2015, the Tianjin port explosion was the most serious dangerous goods safety accident that has occurred in China to date. The accident exposed the imperfect management of dangerous goods in China, poor supervision and management, insufficient education of port personnel and irregular enforcement. However, international treaties on the management of dangerous goods, especially the international standards such as International Maritime Dangerous Goods Code, United Nations Recommendations on the Transport of Dangerous Goods and Revised Recommendations on the Safe Transport of Dangerous Cargoes and Related Activities in port areas, provide comprehensive and effective regulations on various aspects of dangerous goods from definition and classification to transportation, storage, handling and safety management. Korea, a strong maritime transportation country, has also adopted relevant laws such as Safety Management Law of Dangerous Goods and Management Law of Chemical Substances to effectively manage dangerous goods, etc.
The purpose of this study is to compare the laws related to dangerous goods safety management in ports in Korea and China and to discover the problems in China. In addition, it will also study the relevant international regulations, etc., and propose Chinese policies and legal improvements and directions for the management of dangerous goods safety in ports and harbors.
This paper is divided into seven parts.
Chapter 1 Is the introduction of this paper, which describes the background and significance of this paper, and introduces the research content and methodology of this paper.
Chapter 2 Takes International Maritime Dangerous Goods Code, International Convention for the Prevention of Pollution from Ships, Globally Harmonized System of Classification and Labeling of Chemicals and other international conventions as the center, analyzes the definition and classification of dangerous goods, the importance of dangerous goods management in ports, the characteristics of danger, the amount of dangerous goods handling and the impact of danger, etc. It also introduces the relevant legal regulations of dangerous goods in China and international dangerous goods regulations and the content of IMO Revised Recommendations on the Safe Transport of Dangerous Cargoes and Related Activities in port areas and the in port Dangerous goods management regulations. As well as the United States, Japan, Singapore, the Netherlands and other advanced countries in the port of dangerous goods management regulations.
Chapter 3 analyzes the causes and consequences of the explosion at the port of Tianjin, China. Through the Tianjin port accident, this chapter analyzes five points of the overall problems of dangerous goods safety management in China.
Chapter 4 analyzes the legal regulations related to dangerous goods in Korean ports. In this chapter, the definition and classification of dangerous goods, supervision of dangerous goods in ports and harbors, accident response, and transportation and storage of dangerous goods are compared and analyzed, and the problematic points of related legal regulations in China are identified.
Chapter 5 completes the problems of the hazardous materials management system in China's ports and harbors analyzed in Chapter 4. This chapter discusses policy proposals and legal changes, including a comprehensive classification of port hazards, designation of competent authorities for port hazards management, strengthening of corporate characteristics and standardization, introduction of cutting-edge technologies to enhance accident prevention capabilities, flexible application of clear distinctions in port safety risks and accident theory, improvement of education and evaluation systems for port hazards operators, and improvement of port hazards safety evaluation systems. policy proposals and regulations for port hazardous materials management, and revision of the guidelines for evaluating the safety of port hazardous materials operations in China.
Chapter 6 is the conclusion, which includes all the parts covered in Chapters 2 to 6, and the actual situation and problems of China's port hazardous materials management, and proposes policy, legal amendments.CHAPTERⅠ. INTRODUCTION 1
1.1 Background of Research 1
1.2 Significance of Research 3
1.3 Content and methodology of the study 5
CHAPTER II.China and International Dangerous Goods Regulations 7
2.1 Definition of dangerous goods 7
2.2 Classification of dangerous goods 9
2.3 Risk associated with the management of dangerous goods in ports 12
2.3.1 Cargo Volume and Impacts of Dangerous Goods 12
2.3.2 Risk due to dangerous goods in the port 14
2.4 Relevant legislation and regulations of China 18
2.4.1 Work Safety Law 18
2.4.2 Port Law 23
2.4.3 Provisions on the Management of Port Dangerous Goods 24
2.4.4 Regulations on the control over Safety of Dangerous Chemicals 25
2.4.5 Regulations on Port Management 27
2.4.6 Regulations on Safety Supervision and Administration of Dangerous Goods Carried by Ships 28
2.4.7 Other relevant laws and regulations 29
2.5 International regulations of dangerous goods 31
2.5.1 International conventions and rules 31
2.5.2 Relevant laws and regulations concerning dangerous goods in various countries 40
2.6 Revised Recommendations on the Safe Transport of Dangerous Cargoes and Related Activities in port areas 47
2.6.1 Summary of regulations 47
2.6.2 Main contents of the recommendations IMO 48
CHAPTER III. Analysis of accident case at Tianjin Port and management status of dangerous goods at ports in China 56
3.1 Case analysis of explosion accident in Tianjin Port 56
3.1.1 Overview of basic information 56
3.1.2 Risks caused by accidents 57
3.1.3 Investigation result and treatment of explosion cause 59
3.2 Port dangerous goods management in China 60
3.2.1 Illegal operation of related enterprises 60
3.2.2 Poor supervision and management of relevant departments 61
3.2.3 Flurry of regulatory agencies 62
3.2.4 Backward dangerous goods facilities at the port 63
3.2.5 Relevant personnel lack of professional knowledge training 64
CHAPTER IV. A review of Korea's port dangerous goods management regulations and comparison with Chinese regulations 65
4.1 Korea’s relevant Laws and Regulations for dangerous goods in port 65
4.1.1 Safety Management Law of Dangerous Goods 65
4.1.2 Management Law of Chemical Substances 67
4.1.3 Rules for Shipping and Storage of Dangerous Goods by ships 69
4.1.4 Occupation Safety and Health Law 70
4.1.5 Safety Management Law of High-pressure Gases 71
4.1.6 Law of Entry and Departure of ships 71
4.1.7 Guideline for Safety Management of Hazardous Chemical Storage Sites in Ports 72
4.1.8 Other Relevant Laws and Regulations 74
4.2 Comparison of the Laws and Regulations Related to Dangerous Goods between Korea and China, and problems with China’s Law 76
4.2.1 Relevant laws and regulations on the definition and classification of dangerous goods 77
4.2.2 Relevant Laws and Regulations on Port Dangerous Goods Supervision 82
4.2.3 Laws and Regulations Related to the Handling Dangerous Goods accidents at Ports 86
4.2.4 Laws and Regulations Related to the Transport and Storage of Dangerous Goods at Port 89
4.3 conclusion 92
CHAPTER V. Proposal on measures to improve the management system of dangerous goods in port of China 93
5.1 Improvement direction of safety management system of dangerous goods to China 94
5.1.1 Unification of criteria for classification of dangerous goods in ports and clarification of the competent department 94
5.1.2 Strengthen the construction of enterprise specialization and standardization 96
5.1.3 Improving the ability of accident prevention, strengthening the determination of hidden dangers of safety 99
5.1.4 Improving the education and assessment system for dangerous goods operators in port 103
5.1.5 Improve the safety assessment system for dangerous goods in ports 106
5.2 Proposal for amendment of laws and regulations related to dangerous goods to China 108
5.2.1 Amendment to the Provisions on the Management of Port Dangerous Goods——Definition aspect 108
5.2.2 Amendment to the Provisions on the Management of Port Dangerous Goods——Hidden dangers of accidents aspect 109
5.2.3 Amendment to the Detailed rules for the implementation of the examination of hazardous goods operation practitioners of port 111
5.2.4 Amendment to the Safety Assessment Guidebook for Handing in Dangerous Cargo Port 114
CHAPTER VI . Conclusion 118
References 122
국문초록 134
Acknowledgement 138Maste
선박충돌회피 조종의 위험분석에 관한 연구
No full textThe aim of this graduation thesis is to propose a method to evaluate collision risk along ship trajectories, in order to assess the collision risk probability of different encounters. Navigating a vessel includes following a pre-planned trajectory while avoiding collisions as well as other possible risks and thus, accurate evaluations of risks are vital for safe navigation. Utilizing concepts in the domain of collision avoidance and risk assessment is, therefore, imperative in ship manoeuvres in both manned and autonomous/unmanned scenarios. Identifying collision risks along a particular trajectory not only aids in safe navigation but also is vital to assess navigators’ workload in respective path planning.
Experimental simulations done in this study focuses on modelling ship encounters, which essentially avoid collision based on velocity obstacle algorithm, following International Regulations for Preventing Collisions at Sea (COLREGs), and assessing collision risk in different encounter scenarios. A simulation model was developed utilizing velocity obstacle algorithm for collision avoidance, molecular collision theory for the proposed approach for collision risk assessment, and conventional closest point of approach (CPA) model for validating collision risks in respective encounters. The simulation program was able to model head-on, crossing and overtaking scenarios between a particular vessel and multiple target-ships. Collision avoidance manoeuvres were successfully carried out, and collision risk was assessed following the two aforementioned approaches. Results obtained from the study supported the accuracy of the proposed model, thus validating the approach.1. Introduction 1
1.1 Maritime safety regulations and rules in navigation 5
1.2 Ship Safety Domains 10
1.1.1 Quaternion ship domain 13
2. Program Structure and Modeling 17
2.1 Collision avoidance model 19
2.2 Collision risk assessment model 26
2.3 Ship manoeuvring model 31
3. Simulation results and Discussion 37
3.1 Head-on encounter 42
3.2 Overtaking encounter 47
3.2 Crossing encounter 50
3.3 Multi-ship encounter 53
4. Conclusions 57
5. References 59Maste
A Study on the Improvement of Mooring Configuration for Car Ferry in Jeju Port
No full text과거 우리나라 내항 카페리여객선(Car Ferry)들은 해외 중고선 도입에만 의존해왔었다. 세월호 사고 이후 여객선 선령 제한, 선박 검사 강화 및 2018년 연안여객선 현대화 펀드 사업 등으로 인해 2018년을 기점으로 제주항을 기항하는 대부분의 내항 카페리여객선들은 새로운 중고선 및 신조선 도입을 통해 대부분 교체되었다. 이러한 카페리여객선 교체 흐름 속에 여객을 위한 편의⋅오락 시설 확충 및 쾌적한 선내 환경 조성을 통한 여객 영업 이익 확대와 대량의 화물 운송을 통한 운송 이익 증가를 위해 여객선들의 크기 또한 대형화되었다.
이러한 여객선 대형화와 더불어 여객선 사업 활성화로 인해 현재 제주항을 기항하는 카페리여객선의 수도 점점 증가하고 있다. 하지만 제주항 부두시설은 상대적으로 크게 개선되거나 확장되지 못해 제주항 여객선 부두의 접안능력을 초과하는 카페리여객선들이 부두에 계류하는 사례가 계속해서 발생하고 있다. 부두의 설계 접안능력을 초과하는 카페리여객선이 부두에 계류 중일 때 갑작스러운 강한 외력이 작용할 경우 선박의 계류요소별로 허용 가능한 힘을 초과하는 일이 발생하게 된다. 이로 인해 부두 계류시설의 파손뿐만 아니라 선박이 부두에서 떨어지는 상황이 발생하면 여객의 인명사고까지 발생할 수 있는 해양사고로 이어질 수 있기에 적절한 조치 및 대응방안이 필요하다.
본 연구에서는 국내 다양한 계류안전성 평가에 주로 사용되고 있는 선박 계류해석 시뮬레이션 프로그램인 OPTIMOOR 프로그램을 이용하였다. 제주항에 기항하는 내항 카페리여객선 중 제주항 부두설계 한계를 초과하는 크기의 카페리여객선에 대하여 대상 해역에서 발생 가능한 외력 환경조건 속에 현 계류상태에 대한 계류안전성 평가를 수행하였다. 현재 대상부두 및 대상선박의 계류안전성과 계류 환경에 대한 적정성을 검토하고 계류안전성이 취약한 부분은 어떤 요소인지를 파악하고자 하였다. 또한, 대상부두와 대상선박의 계류안전성 평가를 통해 도출된 위험 요소를 개선하기 위한 각종 관련 문헌 및 국외 개선사례를 조사하고 현실적으로 적용 가능한 범위의 개선방안별 특정 외력 조건에서의 계류안전성 민감도 분석을 진행하였다.
그 결과 2부두 아리온 제주호의 경우, 운항자 관점의 개선안 시나리오인 Case 1~4의 경우에는 계선주의 크기로 인한 최대견인력 초과 문제로 인해 계류안전성이 확보되지 못하였다. ‘High Height Bitt’ 추가 설치를 통한 개선안 시나리오 Case 5의 경우 계류삭은 모든 라인이 파단강도의 약 23% 이하의 하중이 작용하고, 계선주도 최대견인력 44% 이하 수준의 하중이 작용하는 것으로 분석되어 계류안전성이 확보되는 것으로 평가되었다. 6부두 퀸메리호의 경우, 여러 개선방안 중 시나리오 Case 5의 경우 계류삭은 모든 라인이 파단강도의 17% 이하의 하중이 작용하고, 계선주도 최대견인력 38% 이하 수준의 하중이 작용하는 것으로 분석되어 계류안전성이 개선되는 것으로 평가되었다.
이러한 연구를 통해 제주항 여객선 부두의 부두설계 접안능력을 초과하는 크기의 카페리여객선들에 대한 계류안전성 관련 정량적 데이터를 바탕으로 계류시설의 위험도와 계류 환경 개선 효과를 확인할 수 있었다. 본 연구 결과는 안전한 여객선 부두시설 구축 및 카페리여객선 계류지침 개발 등을 위한 참고자료로 활용 가능할 수 있을 것으로 기대된다.1. 서 론 1
1.1 연구배경 1
1.2 연구방법 3
2. 연구대상 현황 및 선정 6
2.1 제주항 개요 6
2.2 대상부두 11
2.3 대상선박 12
3. 계류안전성 평가 개요 15
3.1 선박의 계류 15
3.2 계류 선박의 운동 16
3.3 계류 선박에 작용하는 힘 19
3.3.1 풍력 19
3.3.2 조류력 22
3.3.3 파력 23
3.3.4 계류력 24
3.4 계류안전성 평가 모델링 26
3.4.1 평가 개요 26
3.4.2 평가 좌표계 및 부호 규약 28
3.4.3 대상부두 모델링 31
3.4.4 대상선박 모델링 37
3.4.5 환경 외력 조건 설정 42
3.5 계류안전성 평가 시나리오 및 기준 설정 49
3.5.1 외력 조건 및 시나리오 설정 49
3.5.2 계류안전성 평가 기준 설정 49
4. 계류안전성 평가결과 51
4.1 아리온 제주(2부두) 평가결과 51
4.1.1 계류삭 최대장력 52
4.1.2 계선주 최대견인력 55
4.1.3 방충재 최대반력 56
4.1.4 하역안전성 57
4.2 퀸메리(6부두) 평가결과 58
4.2.1 계류삭 최대장력 59
4.2.2 계선주 최대견인력 62
4.2.3 방충재 최대반력 63
4.2.4 하역안전성 64
4.3 종합 분석 결과 65
5. 계류 환경 개선안 분석 67
5.1 계류 환경 개선방안 검토 67
5.1.1 연구사례 분석 67
5.1.2 국외 계류 환경 개선사례 70
5.2 계류 환경 개선 시나리오 도출 및 민감도 분석 72
5.2.1 2부두 개선결과 민감도 분석 72
5.2.2 6부두 개선결과 민감도 분석 80
6. 결 론 88
참고문헌(References) 91Maste
An Investigation of the Conductive Mortar Characteristics for Efficient Cathodic Protection of Reinforced Concrete Structures
No full textThe method of cathodic protection is generally divided into Impressed Current Cathodic Protection (ICCP) and Sacrificial Anode Cathodic Protection (SACP), depending on how electric current is supplied to the structure. ICCP provides current from a rectifier to a cathode (e.g., rebar for concrete structure) through an insoluble anode. In the SACP system, a current flow occurs according to the potential difference between the anode having a lower potential(e.g., aluminum, zinc, and magnesium) and the cathode. ICCP is advantageous in that current strength can be adjusted so that it can be applied to high-resistivity materials. On the other hand, SACP is difficult to be used in such a high-resistance environment because it can only deliver a small amount of current to the cathode, resulting in significant decreases in cathodic protection efficiency and throwing power. To overcome these critical limitations of SACP, the development of conductive mortar is essential to reduce concrete resistivity in tidal and splash zones and maintain its low resistivity for a long time.
This study investigates conductive mortar to improve cathodic protection efficiency by lowering resistivity of mortar. The resistivity characteristics of the mortars that contain electrically conductive admixtures were first studied to reduce resistivity. As the admixtures, activated carbon, zeolite, bentonite and geopolymer that can absorb moisture were used. Activated carbon shows the lowest resistivity among the selected admixtures. As the amount of admixture increases, resistivity tends to decrease. Chemical agents—such as sodium hydroxide, calcium hydroxide, lithium hydroxide, and sodium chloride—were further mixed with admixtures to provide additional conductivity. The performance of chemical agents is highly dependent on the selection of the admixture. Among many combinations, the specimen with sodium hydroxide and activated carbon shows the lowest resistivity, and resistivity can further be reduced by adding chemical agent. Conductive mortar with activated carbon and sodium hydroxide exhibits a 2–4 times higher resistivity reduction than general mortar.
Depolarization tests were conducted to evaluate the SACP system’s performance with the conductive mortars, and the highest depolarization is achieved with activated carbon. 100 mV depolarization is required to ensure sufficient cathodic protection performance, and all specimens in this study have higher depolarization than 100 mV, which demonstrates that the performance of conductive mortar is stably maintained. The current density stabilizes after a while, and higher cathodic protection currents are measured in conductive mortars than general mortars due to their low resistivity. The higher the amount of activated carbon, the higher the cathodic protection current, showing that the mixing ratio is proportional to the cathodic protection performance.
Basic physical property tests were performed, and the results show that conductive mortar can have enough durability and the basic property similar to general mortar. Cathodic protection performance with conductive mortar was tested on a reinforced concrete structure exposed to salt damage. The depolarization measurements were performed at seven piers for three years. The four piers satisfy the 100 mV depolarization standard by NACE International, whereas the three piers do not. SACP performs well during the initial two years of cathodic protection system construction, whereas partial corrosion is observed two years later. However, due to characteristics of sacrificial anodes, there can be slight differences in the measured values depending on the surrounding environment (e.g., changes in tides). Considering that it is the results of the depolarization measurement in the area where variations of the high and low tides occur twice per day, cathodic protection performance is generally good.
Corrosion had already been initiated when the structure was cathodically protected, which makes visual inspection difficult. Thus, steel plates were installed to visually check the corrosion progress. After three years, corrosion is hardly observed on the steel plate in columns with cathodic protection application, while considerable corrosion is observed in columns without cathodic protection system. Therefore, the cathodic protection system works well as intended.
In conclusion, this study first applies the conductive mortar to an reinforced concrete structure in use, and satisfactory results are obtained through six measurements for three years. The conductive mortar developed through this study satisfies all of the electrical conductivity, durability, and other performances that the mortar should have and can be applied to a wider variety of fields.
keywords : conductive mortar, activated carbon, cathodic protection, corrosion, reinforced concrete, resistivity1. 서 론 1
1.1 연구 배경 1
1.2 연구 목적 6
1.3 논문의 구성 7
2. 이론적 배경 9
2.1 철근콘크리트 손상 원인 9
2.1.1 철근콘크리트의 부식기구 10
2.1.2 철근콘크리트의 부식에 영향을 미치는 인자 16
2.1.3 철근콘크리트의 손상 원인 및 유형 18
2.2 철근콘크리트 부식 평가 30
2.2.1 철근의 부식전위 30
2.2.2 염화물량 31
2.2.3 콘크리트 비저항 32
2.2.4 철근의 부식속도 33
2.3 철근콘크리트 보수 방안 36
2.3.1 일반적인 보수 방안 37
2.3.2 전기화학적 보수 방안 40
2.4 혼화재료 51
2.4.1 혼화재 52
2.4.2 혼화제 53
2.5 철근콘크리트 구조물의 유지관리 54
3. 모르타르의 전도성 부여를 위한 혼화재 종류별 특성 59
3.1 서론 59
3.2 실험 방법 61
3.2.1 재료 62
3.2.2 배합 설계 65
3.2.3 시험편 제작 69
3.2.4 측정 방법 71
3.3 실험 결과 및 고찰 76
3.3.1 혼화재에 대한 기공 특성 76
3.3.2 혼화재에 대한 비저항 특성 79
3.3.3 혼화제에 대한 비저항 특성 84
3.4 결론 89
4. 활성탄의 혼입량에 따른 모르타르의 음극방식 특성 91
4.1 서론 91
4.2 실험 방법 97
4.2.1 모르타르 배합 설계 98
4.2.2 시험편 제작 100
4.2.3 측정 및 평가 방법 104
4.3 실험 결과 및 고찰 110
4.3.1 모르타르 내부의 철근 방식전위 거동 110
4.3.3 모르타르 내부의 방식전류밀도 변화 112
4.3.4 4시간 복극전위 측정 결과 114
4.4 결론 116
5. 전도성 모르타르를 이용한 철근콘크리트 구조물의 음극방식 성능 118
5.1 서론 118
5.2 실험 방법 120
5.2.1 전도성 모르타르의 기초물성시험 122
5.2.2 철근콘크리트 구조물 음극방식 128
5.3 실험 결과 및 고찰 138
5.3.1 전도성 모르타르의 기초물성시험 결과 138
5.3.2 철근콘크리트 구조물의 음극방식 결과 144
5.4 결론 148
6. 종합 결론 150
참고문헌 154
국문초록 160Docto
Dynamic Channel Access for Underwater Sensor Networks: A Deep Reinforcement Learning Approach
No full textWe studied the dynamic channel access problem in distributed underwater acoustic sensor netowkrs (UASNs) by using deep reinforcement learning algorithm. First, a multi-agent Markov decision process was applied to formulate the channel allocation problem in UASNs. In an underwater environment, each underwater sensor is considered for the purpose of maximizing the total network data throughput without sending and receiving data or coordinating with other underwater sensors. Then, we propose a deep Q learning-based reinforcement learning algorithm in which each underwater sensor learns not only the channel access behavior of other underwater sensors, but also features such as the channel error probability of the available underwater acoustic channels to maximize total network data throughput. Afterwards, extensive performance evaluation was performed to confirm whether the performance of the proposed algorithm was similar or superior when compared to the performance of the reference algorithms even when implemented in a distributed manner without data exchange between sensors.1. Introduction 1
2. Underwater communication 8
2.1 Acoustic communication 8
2.1.1 Noise 9
2.1.2 Transmission Loss 10
2.1.3 Multipath Propagation 12
2.1.4 Doppler spread 12
2.2 RF & Optical Communication 13
3. Reinforcement Learning 15
3.1 Reinforcement Learning 15
3.2 Q-learning 15
4. Dynamic Channel Access Algorithm 19
4.1 System Model 19
4.2 Problem Formulation 21
4.3 Proposed Algorithm 25
5. Performance Evaluation 27
5.1 Network Environment 27
5.2 Learning Environment 28
5.3 Baseline Schemes 28
5.4 Performance Evaluation 29
6. Conclusion 34
REFERENCES 35Maste
A Study on the determinant of Capital Structure of Chinese Shipbuilding Industry
No full text중국 조선기업 자본구조 결정요인에 관한 연구제 1 장 서 론 1
Ⅰ 연구의 배경 및 목적 1
Ⅱ 연구의 방법 및 구성 4
제 2 장 자본구조에 대한 선행연구 5
Ⅰ 자본구조와 기업가치 5
1. 자본구조 5
2. 기업가치의 함의 및 영향 요소 6
Ⅱ 자본구조에 대한 이론 10
1. 상충이론(Trade-off Theory) 10
2. 자본조달순위이론(Pecking Order Theory) 11
Ⅲ 자본구조에 관한 실증연구 11
1. 한국 문헌 고찰 11
2. 중국 문헌 고찰 13
3. 기타 문헌 고찰 15
제 3 장 실증분석 19
Ⅰ 연구 설계 19
1. 표본기업 선정 및 자료의 수집 19
2. 변수의 선정 21
3. 분석방법론 22
Ⅱ 실증분석 23
1. 기초 통계 분석 23
2. 실증분석 결과 25
제 4 장 결 론 28
Ⅰ 연구 결과의 요약 28
Ⅱ 연구의 의의 및 향후 연구방향 28
참고문헌 30Maste
Study on Effect of Vapor Separation Two-stage Expansion Process in R-134a Household Refrigerator
No full textDue to recent economic growth and industrial development, global energy consumption has been on a steady rise. This requires continuous energy-saving efforts in the refrigerator, which consumes a lot of energy depending on its capacity.
The main source of energy for operating a refrigerator will be the use of electricity produced from fossil energy. As a result, the refrigerators will emit CO2, which is the main cause of global warming, just like the heaters. As such, the operation of the refrigerators has a huge impact on environmental issues. Therefore, it is certain that research to improve the efficiency of refrigerators is very important not only now but also in the future.
The process of the refrigerator is a vapor compressed refrigeration cycle that has already been devised centuries ago and consists of the main constituent facilities: the compressor, the condenser, the expansion device, the evaporator, etc. Various studies have been conducted to improve the efficiency of these refrigerators, but the vapor-separated refrigeration process is nonexistent. In the vapor refrigeration system, the refrigerant vapor hasn't given any role for refrigeration effect in evaporator and only liquid refrigerant can do during phase change from liquid to vapor.
In this study, in a new method to increase the efficiency of the refrigerator, middle expansion process and Vapor-Liquid Seperator were applied to separate refrigerant vapor that had already evaporated and had no effect on the refrigeration before the evaporator was introduced, forming the process of entering the compressor by mixing the vaporized low pressure evaporator refrigerant vapor with the middle pressure separation vapor. and all process analyses were interpreted on the basis of theoretical cycle without heat loss.
For performance evaluation, the Vapor Seperation Two-stage Expansion Process(VSTEP) Refrigeration System was manufactured using R-134a domestic refrigerator with One-stage compression, One-stage expansion cycle and performance evaluation was tested according to conditions such as evaporator and capillary tubes.
The application of VSTEP to domestic refrigerators shows that the area of heat transfer of the evaporator has been reduced by about 20%, and that the time to reach the temperature of the freezer –22℃ at middle pressure 3 bar has been reduced by about 21%, and therefore the power consumption over time has been reduced by about 29%.최근 경제 성장과 산업의 발달로 인하여 세계적으로 에너지 소비량은 꾸준히 상승하고 있는 추세이다. 이에 용량에 따라 많은 에너지가 소비되는 냉동기의 지속적인 에너지 절약의 노력을 필요로 한다.
냉동기를 가동하기 위한 주된 에너지원은 화석에너지로부터 생산되는 전력을 사용하게 된다. 이에 따라 현재 냉동기도 열기기와 마찬가지로 지구온난화의 주범이 되고 있는 CO2를 배출하게 된다. 이와 같이 냉동기의 가동은 환경문제에도 큰 영향을 미치고 있다. 그러므로 냉동기의 효율 개선 연구는 현재뿐만 아니라 미래에도 매우 중요한 일이라는 것은 확실하다.
냉동기의 공정은 증기 압축식 냉동 사이클로 이미 수세기 전부터 고안되었으며, 주된 구성 설비인 압축기, 응축기, 팽창장치, 증발기 등으로 구성된다. 이러한 냉동기의 효율을 향상시키기 위하여 다양한 연구가 수행되어 왔으나, 증기분리식 냉동 공정은 찾기 어려운 실정이다.
냉동기의 냉동 효과는 증발기에서 냉매가 외부 열을 흡입하여 액체 상태에서 기체 상태가 되면서 발휘하게 된다. 그러나 증기 압축식 냉동기는 팽창 과정에서 압력의 저하와 함께 기체가 발생하게 되며, 이미 기체가 된 냉매는 냉동기에 냉동기능을 전혀 수행하지 않게 된다.
본 연구에서는 냉동기의 효율을 높일 수 있는 새로운 방법으로 이미 증발되어 냉동효과와 무관한 냉매 증기를 증발기 유입 전, 분리하기 위하여 중간 팽창의 공정과 액기분리기를 적용, 최종 기화된 저압의 증발기 출구 기체와 중압의 분리 기체를 합하여 압축기에 유입되는 공정을 구성하였고, 모든 공정 해석은 열손실이 없는 이론적 사이클로 기준하여 해석하였다.
성능 평가를 위해 1단 압축 1단 팽창 사이클의 R-134a 가정용 냉장고를 이용하여 실험 장치인 증기분리식 2단 팽창 냉동시스템을 구축한 이후 모세관의 길이, 증발기 형상 등 조건에 따른 성능 평가를 실시하였다.
증기분리식 2단 팽창 공정(VSTEP)를 가정용 냉장고에 적용한 결과 증발기의 전열 면적이 약 20% 감소하였고, 중간 팽창 압력 3 bar에서 냉동실 –22℃ 도달 시간이 약 21% 감소함에 따라 시간대비 소비전력 또한 약 29% 감소하였다.1. 서 론 1
1.1 연구 배경 1
1.2 연구 목적 3
1.3 선행 연구 6
2. 이론적 배경 7
2.1 가정용 냉장고 시스템 분석 7
2.1.1 기존 냉장고 시스템 7
2.1.2 증기분리식 2단 압축(VSTEP) 냉장고 시스템 10
2.1.3 VSTEP 냉장고 중간압력 산정 13
2.2 R-134a 냉매 이론적 특성 15
2.3 VSTEP 냉장고 설계 17
2.3.1 팽창장치 설계 17
2.3.2 열교환기 설계 20
3. 실험장치 및 실험방법 22
3.1 VSTEP 냉장고 제작 22
3.1.1 가정용 냉장고 24
3.1.2 모세관 설계 26
3.1.3 증발기 설계 27
3.2 실험 장치 28
3.3 실험 방법 33
4. 실험결과 및 고찰 34
4.1 기존 냉장고 성능 실험 34
4.2 VSTEP 냉장고 성능 실험 35
4.1.1 모세관 길이에 따른 성능 실험 35
4.1.2 냉매량 변화에 따른 성능 실험 39
4.1.3 증발기 형상에 따른 성능 실험 41
4.3 기존 냉장고와 VSTEP 냉장고 성능 비교 43
5. 결론 47Maste