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The Adhesion Properties of CF/PEKK Composites with PEI and PEEK Adhesive Film in Oven Welding Process
No full textRecently, there has been an increasing movement in the aerospace industry to increase the use of thermoplastic composites. Moreover, interest in fusion bonding and adhesive bonding is increasing because it can reduce cracking, unlike mechanical bonding. In addition, interest in the oven welding process increases in bonding such thermoplastic composite materials by applying fusion bonding and adhesive bonding. However, there is a lack of research on the adhesion performance when using a thermoplastic polymer as an adhesive for bonding using a thermoplastic composite material as a substrate material. In addition, research about the effect of the interphase on an adhesion properties is insufficient, even though adhesive bonding generate interphase through chemical bonding between a substrate and adhesive. And it is unknown whether applying the vacuum bag only(VBO) method to the oven welding process is appropriate.
Therefore, lap shear strength test and fracture surfaces observation through digital optical microscope(Digital OM) and scanning electron microscope(SEM) were performed after bonding by varying the pressing force of carbonfiber/polyetherketoneketone(CF/PEKK) fusion bonding and adhesive bonding using polyetheretherketone(PEEK) and polyetherimide(PEI) as adhesive materials in order to evaluate whether the application of the VBO method is appropriate. In addition, lap shear strength tests were performed at room temperature, 100 and 160 and analysis using Fourier transform infrared spectroscopy(FT-IR) and differential scanning calorimetry(DSC) and fracture surface observation using digital OM and SEM were conducted to understand the adhesion properties of the bonding of PEEK and PEI adhesives having ether and ketone groups. Moreover, the conclusion is as follows.
Applying vacuum pressure by the VBO method was inappropriate when bonding CF/PEKK through oven welding process, as the pressing force was too high. In addition, the PEEK and PEI adhesive bonded CF/PEKK showed higher adhesive strength than the fusion bonded CF/PEKK because the increase of molecular formation of ether, ketone and imide constituting the interphase during the adhesive bonding enhance the adhesive strength. Furthermore, at high temperatures, the tendency of the change in strength differed depending on the type of bonding, which was judged to be due to the formation of adhesive layer, respectively different glass transition temperature, and the increased ductility with temperature increase.
Therefore, this experiment shows the effect of adhesive application having similar chemical structure with thermoplastic of substrate material on the adhesive strength enhancement. In addition, it was suggested that it is essential to consider the glass transition temperature of the adhesive when using the structure to which adhesive bonding is applied in a high temperature environment.1. 서론 1
1.1. 연구의 배경 1
1.2. 연구의 필요성과 목적 3
2. 재료 및 실험 방법 5
2.1. 실험 재료 5
2.1.1. 탄소섬유 5
2.1.2. Polyetherketoneketone(폴리에테르케톤케톤, PEKK) 7
2.1.3. Polyetheretherketone(폴리에테르에테르케톤, PEEK) 9
2.1.4. Polyetherimide(폴리에테르이미드, PEI) 11
2.2 제작 공정 13
2.2.1. 진공 백 성형 공정(Vacuum bag only process, VBO process) 13
2.2.2. 오븐 접합 공정(Oven welding process) 16
2.2.3. 핫 프레스 공정(Hot press process) 20
2.3 특성 분석 시험 23
2.3.1. Lap 전단 강도 시험(Lap shear strength test, LSS test) 23
2.3.2. 푸리에 변환 적외선 분광법(Fourier transform infrared spectroscopy, FT-IR) 30
2.3.3. 시차 주사 열량법(Differential scanning calorimetry, DSC) 32
2.4 파단면 관찰 34
2.4.1. 디지털 광학 현미경(Digital optical microscope) 34
2.4.2. 주사 전자 현미경(Scanning electron microscope, SEM) 36
3. 실험 결과 및 고찰 38
3.1. Lap 전단 강도 시험(LSS test) 결과 38
3.1.1. 실온 Lap 전단 강도 시험 결과 38
3.1.2. 고온 환경 Lap 전단 강도 시험 결과 40
3.2. 푸리에 변환 적외선 분광법(FT-IR) 결과 41
3.3. 시차 주사 열량법(DSC) 시험 결과 45
3.4. 파단면 관찰 결과 47
3.4.1. 디지털 광학 현미경(Digital optical microscope) 파단면 관찰 결과 47
3.4.2. 주사 전자 현미경(SEM) 파단면 관찰 결과 63
3.5. 고찰 71
4. 결론 75
참고문헌 78
국문초록 83
감사의 글 86Maste
SWAN을 이용한 한반도 재해성 파랑 수치모의
No full textIn this study, we simulated the hazardous waves induced by typhoons and for the winter season in the Korean Peninsula. The third-generation numerical wave model SWAN(Simulating WAves Nearshore) was used for the simulation. As input forcing of the numerical wave model, the meteorological forecast data of RDAPS and JMA-MSM were used. We analyzed the sensitivity of input forcing data with re-analysis data of ERA5. Also, we constructed the sea surface wind field of tropical cyclones by using JTWC's best track data and Holland model for simulation storm waves induced by typhoons. For further research, we established a nested model for the simulation of storm waves induced by typhoon Maysak and Haishen, which are considered the most severe incidents in the simulation periods. For the source terms of energy generation by wind and white-capping dissipation, we used Komen and ST6 package formula. In the end, we conducted statistical analysis to validate the wave model by comparing its result with observation data of waves from the WINK system. As a result, SWAN with ST6 and RDAPS showed the best performance in the wave height simulation of winter storm waves. On the other hand, using a formula of Komen with the same input forcing showed the better in the wave height simulation of storm waves induced by Typhoons in the Korean Peninsula. But the prediction of a wave period parameter needs further research or approaches to improve the prediction accuracy.1. Introduction 1
2. Numerical Model 4
2.1 Numerical Wave Model 4
2.1.1 SWAN (Simulating WAves Nearshore) 4
2.1.2 Sin and Sds,w : Komen et al.(1984) 5
2.1.3 Sin and Sds,w : ST6 (Rogers et al.,2012) 7
2.1.4 Wind Drag Coefficient 10
2.2 Set-Up 10
2.3 Input Forcing 14
2.3.1 RDAPS 17
2.3.2 JMA-MSM 17
2.3.3 ERA5 18
2.3.4 JTWC's Best Track 19
3. Scenario 20
3.1 Simulation Period 20
3.2 Observation Data 23
3.3 Numerical Parameter of Source Term 26
4. Result and Validation 29
4.1 Validation of Input Forcing 29
4.1.1 Non-Typhoon (Winter Season) 29
4.1.2 Typhoon 36
4.2 Result of Wave Simulation 49
4.2.1 Non-Typhoon (Winter Season) 49
4.2.2 Typhoon 59
4.2.3 Nested Model 74
5. Discussion & Conclusion 79
Reference 82Maste
Theme and Thematic Progression in Argumentative Essays by Vietnamese EFL Learners
No full textEnglish as foreign language (EFL) learners in general and Vietnamese EFL learners in particular might find that writing is a task of challenge, even advanced EFL learners who have good competence in grammatical structures and lexical resources might struggle in producing coherent writing that meets native English speakers’ expectation. Observing the coherenre problems that Vietnamese EFL learners have encountered, I collect a number of their academic essays, specifically argumentative writing to analyze theme and thematic progression (TP) patterns, which is recognized as one of ways to analyze textual features to identify how themes unfold the text. Specifically, this study examines theme choices and TP patterns used in argumentative writings by Vietnamese EFL learners and by American professional writers to see the differences in usage of themes and TP patterns between two groups. To identify these differences, both qualitative and quantitative methods are used in this study. These differences can be attributed to several factors, including rhetorical conventions, overuse of cohesive devices, translation from first language (L1), as well as side effects of second language (L2) training. These factors might make learners’ writing incoherent, less convincing, and hard to follow. To help Vietnamese EFL learners recognize these factors and improve coherence in their writing, a training course on theme and TP patterns is developed. This course might provide basic theories about themes and TP patterns, and guide EFL learners to make the theme choices and use TP patterns to create smooth flow of ideas to achieve success in their English writing.Chapter 1 Introduction 1
1.1 Research Context 1
1.2 Aims and Scope of the Study 3
1.3 Significance of the Study 4
1.4 Organization of the thesis 4
Chapter 2 Literature Review 6
2.1 Contrastive Rhetoric and Academic Writing 6
2.1.1 Contrastive rhetoric 6
2.1.2 Vietnamese and English Academic Writing 7
2.2 Coherence, Themes, Thematic Progression 8
2.2.1 Definitions of Coherence 8
2.2.2 Theme 12
2.2.3 Thematic Progression 15
2.3 Studies on Themes and TP in EFL/ESL Writing
compared to Native Writing 19
2.3.1 Studies on Themes in EFL/ESL Writing 19
2.3.2 Studies on Thematic Progression in EFL/ESL Writing 21
2.3.3 Studies on TP patterns in essays written by Vietnamese
EFL Learners 22
2.4 Teaching Theme and TP in an EFL Writing Course 23
2.5 Research Questions 24
Chapter 3 Research Design 26
3.1 Overall Research Design 26
3.2 Research Setting 26
3.3 Participants and Data 27
3.4 Procedures of Analysis 29
3.4.1 The unit of analysis 29
3.4.2 Division of Theme and Rheme 30
3.4.3 Identification of Thematic Reiteration 32
3.4.4 Thematic Progression patterns 33
3.4.5 Steps of analysis 34
3.5 Inter-rater Reliability 36
3.6 Statistical Procedures 37
Chapter 4 Results and Discussions 38
4.1 Topical, Textual and Interpersonal Themes 38
4.1.1 Interpersonal Themes 38
4.1.2 Textual Themes 43
4.2 Theme Markedness 48
4.3 Thematic Progression Patterns 53
4.4 Overall Findings 60
Chapter 5 Application 61
Chapter 6 Conclusion 65
6.1 Summary of the Findings 65
6.2 Limitations 65
References 67
Appendices 75
Appendix 1 General Characteristics 75
Appendix 2 Theme Types 78
Appendix 3 Thematic Progression Patterns 81
Appendix 4 Essays 83Maste
A Study on the Development of Performance Evaluation Method of eLoran Time Synchronization
No full text본 논문은 GNSS(Global Navigation Satellite Systems)의 백업시스템으로 알려진 eLoran(enhanced Loran)이 제공하는 Timing 정보를 이용한 시각동기 성능이 얼마나 정확하고 안정적인지 평가하기 위한 기법을 개발 및 검증하는 과정에 대하여 기술하였다.
eLoran 시스템 현황과 국내․외 기술개발 및 정책 동향을 분석하고 시각동기 성능평가관련 선행연구 등의 분석을 통해 eLoran 시각동기 요구 성능과 성능평가 항목 및 기준을 도출하여, Timing 정확도와 신호의 품질을 종합적으로 평가하는 eLoran 시각동기 성능평가기법을 설계하였다.
설계된 성능평가기법을 검증하기 위하여 국내 기술개발로 개발․구축한 eLoran 테스드베드에 실제 적용하여, 평택 보정기준국에서 수신된 인천 시험송신국의 2021년 8월 한 달간 데이터를 대상으로 시각동기 성능평가를 실시하였다.
평가결과를 요약하면, Timing 정확도는 LDC(Loran Data Channel) 보정 전 43.71㎱, 보정 후 22.52㎱로 요구 성능(＜100㎱)을 충족하였으며, 신호품질은 SS(Signal Strength) 61㏈㎶/m, SNR(signal to Noise Ratio) 9.4㏈, ECD(Envelop to Cycle Difference) 0.25㎲로 모두 평가 기준 값을 충족하였다. 그러나 SNR은 분석대상 데이터의 61%만 평가 기
준 값을 충족하는 결과를 보여 수신지점에서 SNR 개선을 위한 별도의 조치가 필요한 것으로 분석되었다. 주․야간 전파전파(電波傳播) 특성에 따른 Timing 정확도는 주간에 비해 야간에 약간 감소(LDC 보정 전 약 11.2%, 보정 후 약 0.6%) 하였으나 두 가지 경우 모두 Timing 정확도 요구 성능을 충족하는 결과를 보여주었다.
eLoran 시각동기 성능평가기법은 Timing 정확도와 Timing 정확도에 영향을 미치는 신호의 품질과 전파전파 특성을 종합적으로 분석․평가함으로써 평가결과에 대한 신뢰성을 제고할 수 있는 평가기법임을 검증하였다. 또한 이 평가기법을 통해 eLoran은 정밀시각공급원으로서 단독 또는 GNSS 백업시스템으로 활용할 수 있음을 확인할 수 있었다.
본 논문은 eLoran 서비스 제공자 및 이용자가 eLoran 시각동기 성능을 평가하거나 신호의 품질을 관리하는데 매우 유용하게 활용할 수 있을 것으로 기대된다.제1장 서 론 1
1.1 연구 배경 및 목적 1
1.2 연구 방법 및 논문구성 5
제2장 eLoran 시스템 현황 분석 7
2.1 eLoran 개요 7
2.2 국내 기술개발 및 테스트베드 구축 현황 21
2.3 국제기구와 외국의 정책 동향 60
제3장 eLoran 시각동기 성능평가기법 설계 76
3.1 시각동기 성능평기기법 개발 필요성 76
3.2 시각동기 요구 성능 80
3.3 시각동기 성능평가기법 설계 82
제4장 eLoran 시각동기 성능평가기법 검증 93
4.1 시각동기 성능평가기법 적용 93
4.2 시각동기 성능평가기법 검증 105
4.3 검증된 시각동기의 경제성 효과 107
제5장 결론 113
참고문헌 115Docto
Fatigue Life Assessment of a Container ship for Stowage plan
No full text선박의 피로 수명 평가는 선박이 일생 동안 받는 동적 하중이 선체 구조에 응력을 발생시킬때 응력 집중부에 누적된 피로 손상으로 인한 파단의 시점을 예측하는 것이다. 선박의 피로 수명를 평가하기 위해서는 선박이 일생 동안 받는 응력 사이클 분포를 예측할 필요가 있다. 따라서 S-N 선도 뿐만 아니라 파도에 의한 동적 하중을 얻기 위한 내항성능 해석과 응력 전달 함수를 구하기위한 선체 구조 해석이 요구된다. 또한, 선박의 적재 조건 및 해상 상태와 같은 운항적인 요소도 이해할 필요가 있다. 각 선급들마다 피로 수명 평가 절차서가 잘 마련되어 있어 선종별 운항 특성을 고려한 합리적인 피로 해석이 수행되고 있다. 하지만, 컨테이너선의 경우 선종의 특성상 화물로 인한 중량 분포가 매 정박지마다 임의로 변하기 때문에, 실제 화물의 적재 조건을 고려하기 어렵다. 화물의 중량 분포는 피로 손상의 주요 요인이 되는 선체 거더 하중과 관련이 있으나 설계 단계에서는 균일 중량 화물을 사용한 Scantling draft 하중 조건에서 보수적인 피로 손상으로 선박의 피로 수명을 평가하는 것이 일반적이다. 본 연구에서는 컨테이너 선박의 화물 중량 분포가 피로 수명에 미치는 영향을 파악하기 위해서 스펙트럴 피로 해석을 이용하여 적화 계획에 따른 다양한 하중 조건에서 Hatch coaming 상단의 피로 수명을 평가하였다. 화물의 중량 분포를 고려한 적화 계획에 따라 컨테이너선의 피로 수명이 관리될 수 있음을 확인하였다. 따라서, 만약 선박의 적화계획이 피로 수명이 증가되는 방향으로 수립된다면 화물의 배치만으로 선박의 구조 건전성을 증대 시킬 수 있을 것이다.Fatigue life assessment is the analysis that estimates the time to crack initiation in the stress concentration area by the fatigue damage accumulation as the dynamic load that a ship experiences during its lifetime generates the stress in the hull structure. To estimate the fatigue life of the ship structure, it is necessary to predict the stress cycle distribution that a ship is expected to experience during its lifetime. So, seakeeping analysis to determine wave-induced dynamic load and structural analysis for stress transfer function as well as S-N curve are required. In addition, it is necessary to understand the ship’s operational factors such as the loading conditions and sea states. Each classification has its procedures for fatigue life assessment, so that reasonable fatigue analysis is being performed considering the operational characteristic according to ship’s type. However, in the case of a container ship, since the weight distribution by the cargo changes arbitrarily in every port of call, it is difficult to consider the actual loading conditions. The weight distribution of cargo is related to the hull girder load which is a major factor in fatigue damage, but It is common to estimate the fatigue life of a container ship under the scantling draft loading condition using the homogeneous cargo weight at the design stage, which is resulting in conservative fatigue damage. In this study, the fatigue life of hatch coamings was calculated using spectral fatigue analysis under the various loading conditions considering a stowage plan to see the impact of the weight distribution on fatigue life in a container ship. It was found that the fatigue life of the container ship can be handled by the weight distribution of the cargo. Therefore, if the stowage plan of container ships is established in the direction of increasing the fatigue life, the structural integrity of ships would be increased only by arranging the cargo.1. 서 론 1
1.1 연구의 배경 1
1.2 연구의 방법 및 목적 3
2. 선박의 피로 해석 절차 6
2.1 선박의 피로 해석 절차 6
2.2 선종별 피로 해석 차이 7
2.2.1 선종을 고려한 해석 위치 7
2.2.2 화물의 형태에 따른 하중 변화 9
2.2.3 선종에 따른 운항 패턴 10
2.3 본 연구의 피로 해석 절차 11
3. 스펙트럴 피로 해석 12
3.1 선박의 제원 12
3.2 Numerical modelling 13
3.2.1 해석 위치 선정 13
3.2.1 Fine mesh 모델링 14
3.3 선박 중량 모델링 15
3.3.1 선체 중량 분포 생성 15
3.3.2 컨테이너 화물 모델링 절차 18
3.3.2 컨테이너 화물 모델링 프로그래밍 21
3.4 내항성능 해석 26
3.5 구조 해석 27
3.6 응력 전달 함수 29
3.6.1 Pressure mapping 29
3.6.2 응력 전달 함수 (Stress RAO) 30
3.7 파랑 하중 모델 31
3.8 피로 손상 계산 33
3.8.1 S-N 선도 33
3.8.2 선형 누적 피로 손상 34
3.8.3 피로 손상 모델 35
3.8.4 피로 손상 계산 37
4. 컨테이너선의 적화 계획을 고려한 하중 조건 39
4.1 컨테이너선의 적화 계획 이해 39
4.1.1 크기에 따른 고려사항 39
4.1.2 종류에 따른 고려사항 40
4.1.3 중량에 따른 고려사항 41
4.1.4 Visibility rule 준수사항 41
4.2 피로 해석 Case 선정 절차 43
4.2.1 적화 계획시 고려되는 선박 운항 지표 43
4.2.2 화물 적화 계획 절차 45
4.2.3 화물의 중량 배치시 고려사항 46
4.2.3.1 경하 중량에 따른 Trim 변화 47
4.2.3.2 경하 중량에 따른 정수중 굽힘 모멘트 변화 48
4.2.4 평형수 중량 모델링 49
4.2.5 피로 해석 Case 50
5. 적화 계획에 따른 피로 수명 평가 및 비교 55
5.1 피로 수명 해석 결과 55
5.1.1 Hatch coaming 구조의 피로 손상 55
5.1.2 하중 조건에 따른 피로 수명 평가 56
5.2 피로 수명과 운항 매개 변수의 관계 62
5.2.1 정적 하중에 의한 매개 변수와 피로 수명의 관계 62
5.2.1.1 정수중 굽힘 모멘트와 피로 수명의 관계 62
5.2.1.2 선박의 중량 제원과 피로 수명의 관계 64
5.2.1 동적 하중에 의한 매개 변수와 피로 수명의 관계 67
6. 결 론 76
참고문헌 78Maste
MOCVD 방법에 의해 4H-SiC 기판 위에 성장한 Ga2O3 박막의 결정상 변화에 대한 연구
No full textβ-Ga2O3의 고기능 소자 제작과 열방출 문제 해결을 위해 hetero-epitaxy 성장이 중요하다. 그래서 본 연구에서는 표면 거칠기를 위해 유기 금속 화학 증착법(MOCVD)으로 4H-SiC 기판 위에 여러 가지 성장 조건에서 ε-Ga2O3 박막들을 성장하는 실험을 수행하였다. 후에 β-Ga2O3의 전도성 이용을 위해 고온 열처리를 이용하여 결정 상(crystal phase) 전이에 의한 β-Ga2O3 박막들을 형성하였다. ε-Ga2O3 박막의 결정질은 성장온도는 665°C, 산소유량은 200sccm 조건에서 성장한 경우가 가장 좋은 조건 임을 알 수 있었고 상전이(Transformed) β-Ga2O3 박막은 ε-Ga2O3 박막을 665℃에서 산소유량이 200sccm로 성장한 후 산소 분위기로 900℃에서 10분간 열처리를 진행하였다. ε-Ga2O3 박막 성장의 경우, 육각형 모양의 핵생성 이후 박막 성장이 이루어지는 것을 확인할 수 있었으며, 육각형 핵 결정들의 배열 방향은 기판의 결정 방향과 밀접한 관계가 있음을 알 수 있었다. 그러나 육각형 모양의 핵 생성 후 2차원으로 형성된 ε-Ga2O3 박막의 결정 구조는 hexagonal 구조가 아니고 orthorhombic 구조를 가지고 있음을 XRD 분석을 통하여 확인할 수 있었다. 또한, 결정상 전이에 의한 방법이 아닌, 직접 β-Ga2O3 결정상 성장 방법으로 형성한 박막과 transformed β-Ga2O3 박막의 결정성을 비교 분석하였다. 직접 β-Ga2O3 결정상 성장 방법으로 형성한 박막에 비하여, ε-Ga2O3 결정상에서 β-Ga2O3 결정상으로 전이된 박막의 결정성이 훨씬 우수한 것을 확인할 수 있었다.Ga2O3 hetero-epitaxy growth is important for manufacturing high-performance devices of β-Ga2O3 and solving heat dissipation agents. In this study, experiments were carried out to grow ε-Ga2O3 thin films under various growth conditions on a 4H-SiC substrate using metal-organic chemical vapor deposition(MOCVD) for surface roughness. Later, for the conductivity of β-Ga2O3, β-Ga2O3 thin films were formed by crystal phase transition using high-temperature heat treatment. It was found that the best condition for the crystalline quality of the ε-Ga2O3 thin films was grown at a growth temperature of 665°C and an oxygen flow rate of 200 sccm. For the transformed β-Ga2O3 thin film, the ε-Ga2O3 thin film was grown at 665°C with an oxygen flow rate of 200 sccm, and then annealed at 900°C for 10 minutes in an oxygen atmosphere. In the case of ε-Ga2O3 thin film growth, it could be confirmed that thin film growth was performed after hexagonal nucleation, and the arrangement direction of hexagonal nuclei was closely related to the crystal direction of the substrate. However, it was confirmed through XRD analysis that the crystal structure of the ε-Ga2O3 thin film formed in two-dimension after hexagonal nucleation had an orthorhombic structure. In addition, the β-Ga2O3 thin film grown directly on 4H-SiC and the transformed β-Ga2O3 thin film were compared and analyzed. It was confirmed that the crystallinity of the thin film transferred from the ε-Ga2O3 crystal phase to the β-Ga2O3 crystal phase was much better than the thin film formed by the direct β-Ga2O3 crystal phase growth method.1. 서론 1
2. 이론 3
2.1 전력반도체 3
2.2 Ga2O3 6
2.3 ε-Ga2O3, β-Ga2O3 8
2.4 ε-Ga2O3의 물리적 특성 9
3. 실험 방법 10
3.1 MOCVD 10
3.2 ε-Ga2O3 박막 성장 조건 12
3.3 β-Ga2O3 열처리 조건 13
3.4 측정 장비 및 방법 14
3.4.1 XRD 14
3.4.2 SEM 16
3.4.3 AFM 18
4. ε-Ga2O3의 상 제어 20
4.1 SiC 결정면의 영향 20
4.1.1 SEM 분석 20
4.1.2 XRD φ scan 분석 23
4.2 유량과 온도의 영향 26
4.2.1 현미경 분석 26
4.2.2 XRD ω-2θ scan 분석 28
4.2.3 XRD rocking curves 분석 30
5. β-Ga2O3의 상 제어 33
5.1 상전이 온도의 영향 33
5.1.1 XRD ω-2θ scan 분석 33
5.1.2 SEM 분석 35
5.1 Ga2O3 결정상에 따른 박막의 영향 37
5.1.1 XRD ω-2θ scan 분석 37
5.1.2 SEM, AFM 분석 39
5.1.3 XRD rocking-curve 분석 41
6. 결론 44
7. 참고문헌 45Maste
A Study on the application of Shaft-generator and battery system to satisfy the Energy Efficiency eXisting ship Index regulation (EEXI)
No full text선박에너지효율 설계지수(EEDI) 규정이 도입된 2013년 이후, 새로이 건조되어 운항하는 선박의 경우, EEDI 단계별 허용치를 만족하여야만 국제에너지효율증서(IEEC) 증서를 발급받아 국제항해가 가능하다. 즉 건조년도에 따른 EEDI Phase를 적용 받은 선박의 경우, 건조 단계부터 온실가스 저감을 위해 선형개발, 청정연료 사용 또는 에너지 저감장치(ESD) 설치 등을 고려하여 설계되고 있다.
하지만 2013년 이전 건조선박 또는 2013년 이후 건조선박이라 할지라도 낮은 단계의 EEDI Phase를 적용 받는 선박의 경우, 실제 온실가스 저감 효과가 미비할 뿐 아니라 추가의 에너지효율 개선이 강제화 되지 않기 때문에, IMO 온실가스 감축전략 목표달성을 위한 추가의 규제가 불가피해 진 상황이다.
이에 따라, 2023년 1월 1일 이후 도래하는 정기적 검사 시 까지 현존하는 모든 에너지효율 협약적용 대상 선박에 대하여, 에너지효율 개선을 위한 기술적 조치인 현존선 에너지효율지수(EEXI) 규정을 만족해야만 IEE 증서를 발급 가능하도록 MARPOL 부속서 6 이 전면개정 되었다.
즉 현존하는 모든 협약 적용선박에 대한 EEXI 규제의 적용이 강제화 됨에 따라, 친환경 선박 기술 적용 및 대체에너지 사용은 협약 규정 만족을 중요한 방안으로 고려되고 있으며, 이를 위한 IMO에서의 연구 또한 통신작업반 및 MEPC 회의를 통해 실시간으로 진행 중이다.
허나, 현 시점에서 고려될 수 있는 현실화된 친환경 선박 기술에 대한 구체적인 구분 및 적용 방법 등이 가시화되지 않았으며, 해당 기술의 도입 시 고려되어야 하는 배출가스 저감에 대한 공통 지표, 기준 및 규정 등이 정해지지 않은 상태이다.
이에 따라, 본 연구에서는 선박의 실제 운항 Profile에 따라, 축발전기 및 배터리 사용을 통해 실질적으로 개선할 수 있는 EEXI 지수를 분석해 보았으며, 운항 및 정박 시 얻을 수 있는 에너지효율 향상 가능성을 비교하여, 현존 운항선박에 대한 적용 가능성을 확인하고자 한다.제 1 장 서 론 1
1.1 연구배경 1
1.2 연구내용 4
1.3 논문의 구성 5
제 2 장 선박에너지 효율 규제의 개요 및 동향 7
2.1 선박에너지효율설계지수 7
2.2 현존선 선박에너지효율지수 9
2.2.1 EEXI 규제 도입을 위한 지침서 12
2.2.2 MEPC.333(76) 13
2.2.3 MEPC.334(76) 14
2.2.4 MEPC.335(76) 15
2.3 EEXI 규정 적용 대상 선박 16
제 3 장 강화되는 선박에너지 효율규제 만족을 위한 친환경 기술 및 대체연료에 대한 분석 19
3.1 IMO에서 논의 중인 친환경 기술 및 대체연료 19
3.1.1 Battery electric vessel 19
3.1.2 Battery Hybrid vessel 20
3.1.3 Hydrogen 21
3.1.4 Fuel cell 23
3.1.5 Air cavity/Air lubrication systems 24
3.1.6 Ammonia 25
3.1.7 Solar power 26
3.1.8 Power take-off/out 27
3.2 친환경 기술 적용을 위한 EEXI 수식 검토 28
제 4 장 축발전기 및 배터리 적용 대상선박 및 선박 운항 시 출력 변경에 따른 연료소모량(SFOC) 값 분석 30
4.1 대상 선박 선정 31
4.2 선박 부하 환경 분석 32
4.3 선박 부하 환경 에 따른 SFOC 분석 36
제 5 장 항해 중 축발전기 및 배터리 사용에 따른 EEXI 지수 40
5.1 축발전기 제원 40
5.2 배터리 제원 40
5.3 축발전기 및 배터리 사용 시 주기관 및 발전기 출력 42
5.4 축발전기 및 배터리 사용 시 SFOC 비교 45
5.5 축발전기 및 배터리 사용에 따른 EEXI 지수 분석 46
제 6 장 정박 시 배터리 사용에 따른 EEXI 지수 49
6.1 정박 시 배터리 사용에 따른 주기관 및 발전기 출력 49
6.2 정박 시 배터리 사용에 따른 SFOC 비교 50
6.3 정박 시 배터리 사용에 따른 EEXI 지수 분석 52
제 7 장 결 론 54
참고문헌 56Maste
Focusing on Risk and Brand Perspective
No full textThe 4th industrial revolution is changing modern society dramatically from the way people used to live and the mode businesses used to operate. With the trend of digitalization and globalization, the conventional economic activities and financial systems are also deeply reshaped. The banking industry, playing a dominant role in financial systems, is also transformed from “the business of saving money” to “the business of money” and currently “the business of customers”. Nowadays, the bank industry faces two major challenges. On the one hand, brought by digitalization, the rapidly growing business volume challenges the bank’s customer risk estimation. In addition, the strengthened regulatory requirements also raised expectation for higher efficiency and accuracy. On the other hand, brought by globalization, banks also faced the challenge of obtaining a superior position from the local, foreign, and Fintech competitors. Therefore, this thesis focuses on strengthening the competitiveness of commercial banks by decreasing the risk brought by customers and increasing the brand value of banks. Specifically, this thesis addresses the following three main contributions:
First of all, an accurate and efficient customer risk-level classifier is developed with neural network at the account opening service, which provides a first-gated risk assessment for customers. Experimental results showed that the proposed method achieved 96.7% accuracy, which surpasses existing methods. Such an automatic and labor-saving risk-level classifier is a crucial step to efficiently mitigate banks’ potential risks and losses, which also benefits the brand of banks.
Secondly, to generate more connections with new customers, a bank-oriented study is developed to systematically investigate the impact of bank brand value from macro, meso, and micro levels with multi-variables regression analysis. The importance of the three levels of factors is numerically estimated respectively. Micro-level is found to play the most influential role. Consequently, a further investigation between the micro-level variables and bank brand value is explored. The findings guide the bank managers to optimize resource allocation. By grasping the core of the brand value development, banks can attract more customers so that obtain a superior position in the market.
Thirdly, a comparison study of the top banks in China and Korea is conducted. As the key representatives of emerging economies and developed economies respectively from East Asia, both China and Korea show increased importance and influence on the global stage. The findings of this study show commonalities and heterogeneities of factors that contribute to a bank’s brand value in both markets, suggesting that customized strategy should be applied to fit the different economic realities of bank’s-based country.Chapter 1 Introduction 1
1.1 Background 1
1.2 Purpose of Research 4
1.3 Methodologies and Key Contributions 8
1.4 Organization of the Thesis 9
Chapter 2 The First Gate Customer Risk Assessment 12
2.1 Risk Assessment in the Retail Banking Business 12
2.1.1 External environment: digital economy and finance 12
2.1.2 Changes in the environment of banking business 15
2.1.3 Challenges to the banking business 16
2.2 Limitations of Existing Customer Risk Assessment Frameworks 18
2.3 First Gate Risk Assessment: Procedures in Account Opening Service 25
2.4 Automatic Customer Risk-level Classifier with the Neural Network at the Account Opening Service 30
2.4.1 Data collection and preprocessing 33
2.4.2 Feature extraction 35
2.4.3 2-staged NN-based customer’s risk classification model 45
2.5 Experimental Results and Analysis 49
2.5.1 Overall performance 52
2.5.2 Comparison with other machine learning algorithms 52
Chapter 3 Strengthen the Brand in the Banking Business 55
3.1 The Role of Brand in Banking Business 55
3.2 Customer-oriented Brand Studies in the Banking Business 58
3.3 Bank-oriented Brand Studies 60
3.4 Bank Core Competence Model 62
3.5 Importance Analysis with Multi-variable Linear Regression 72
3.5.1 Data collection 72
3.5.2 Data preprocessing: principal component analysis 74
3.5.3 Multivariable regression analysis 78
3.5.4 Multicollinearity problem: stepwise regression 79
3.6 Results and Analysis 80
3.6.1 PCA based factor analysis in three levels 80
3.6.2 Analysis of the benchmark regression 83
3.6.3 Stepwise regression with Micro level variables 85
3.6.4 Comparison between banks in Korea and China 88
Chapter 4 Discussion and Implication 93
4.1 Implications of Bank’s Risk Assessment 93
4.2 Implications of Bank’s Brand Value 95
4.3 The Implication of Brand Value Improvement with Strengthened Risk Control are Inseparable in Bank Business 98
Chapter 5 Conclusion 101Docto
Development of Low Heat Self-consolidating Concrete for Tall Building MAT Foundation construction in Maritime Environment
No full textRecently, buildings are becoming larger and taller and many tall buildings are being built around the coast for great views. Therefore, high strength, high flow concrete for tall buildings is required and concrete according to each properties is required, such as high durability concrete in the marine environment and a method to control the heat of hydration generated during large-scale concrete pouring. However, in the planning and construction of tall buildings in the marine environment, there is little in the way of deriving an optimized combination and constructing and analyzing data on the actual construction performance related. In this study, the correlation of low heat and self-consolidating concrete is analyze based on the analysis and measurement of the performance requirements related to the concrete mixed design required for the construction of tall buildings in the marine environment.
The results of this study are summarized as follows.
(1) In order to give low heat self-consolidating performance, the water/binder ratio was set at 34.4%, the fine aggregate ratio 54%, the mixing water 155kg/㎥, and the binder amount 450kg/㎥. And a specific concrete mixing design was derived in which the ratio of the 4-component mixed cement was 18% cement, 50% blast furnace slag, 27% fly ash, and 5% silica fume. As a result the quality control standards for the slump flow of 650±50㎜, air volume of 3.5%±1.5, and design standard strength of 45MPa, that they require performance is satisfied.
(2) The carbonation coefficient is , which is judged that the carbonation resistance performance is very good. And result of evaluation of salt resistance performance and sulfuric acid resistance performance, chloride-ion penetration characteristics were stable, and it was found to be applicable to severe sulfate environmental conditions.
(3) Through the adiabatic temperature rise test, the maximum adiabatic temperature rise( K ) was 28.1℃, and the reaction rate (α) was 0.924℃/hr. It is judged to represent the performance of low heat concrete.
(4) Through actual construction, the maximum hydration temperature was measured at 45.3℃, which is about 60% compared to similar sites, and curing period can be shortened up to 43 days, which is judged to have low heat properties.
(5) In the future, it is judged that high quality construction will be possible if the mixing factors for each required performance established in this study are used in the marine environment MAT foundation concrete mixing design with a design strength of 45MPa.1. 서 론 1
1.1 연구의 배경 및 목적 1
1.2 기존 연구의 동향 3
1.2.1 자기충전 콘크리트 개발 3
1.2.2 고내구성 콘크리트 개발 4
1.2.3 저발열 콘크리트 개발 6
1.3 연구방법 및 범위 9
2. 해양환경 매트기초 예비적 고찰 11
2.1 서론 11
2.2 해양환경 매트기초 콘크리트 요구성능 11
2.2.1 자기충전 콘크리트 11
2.2.2 저발열 콘크리트 13
2.2.3 고내구성 콘크리트 21
2.3 소결 37
3. 저발열 자기충전 콘크리트 최적배합설계 38
3.1 서론 38
3.2 배합설계 개요 39
3.2.1 품질관리 기준 39
3.2.2 기술적 요구사항 검토 40
3.2.3 배합설계계획 40
3.2.4 사용재료 특성 41
3.3 실내 배합시험 44
3.3.1 개요 44
3.3.2 결합재 구성에 따른 실내 배합시험 44
3.3.3 시멘트 비율 조정에 따른 실내 배합시험 50
3.3.4 단위수량 조정에 따른 실내 배합시험 53
3.3.5 실내 배합시험 결과 56
3.4 레미콘 B/P 생산시험 57
3.4.1 개요 57
3.4.2 레미콘 B/P 생산시험 58
3.4.3 레미콘 B/P 생산시험 결과 59
3.5 소결 64
4. 해양환경 콘크리트 내구성능 평가 65
4.1 서론 65
4.2 내구성능 평가 방법 65
4.2.1 개요 65
4.2.2 역학적 특성 평가 방법 66
4.2.3 중성화 저항 성능평가 방법 66
4.2.4 내염해 성능평가 방법 67
4.2.5 내황산 성능평가 68
4.3 내구성능 평가 결과 70
4.3.1 역학적 특성 평가 결과 70
4.3.2 중성화 저항 성능평가 결과 71
4.3.3 내염해 성능평가 결과 72
4.3.4 내황산 성능평가 결과 76
4.4 소결 79
5. 저발열 콘크리트 수화발열 특성 평가 80
5.1 서론 80
5.2 단열온도 상승시험 80
5.2.1 개요 80
5.2.2 단열온도 상승 시험 결과 82
5.2.3 온도보정 결과 83
5.3 수화발열 특성 해석 85
5.3.1 개요 85
5.3.2 발열특성 조건 85
5.3.3 열특성 계수 86
5.3.4 콘크리트 강도 조건 86
5.3.5 외기온도 조건 87
5.3.6 온도균열 관리기준 88
5.3.7 수화발열 특성 해석 결과 89
5.4 온도균열 저감을 위한 양생방안 검토 94
5.4.1 양생방안 검토개요 94
5.4.2 Case 1 검토결과 95
5.4.3 Case 2 검토결과 99
5.4.4 Case 3 검토결과 103
5.4.5 양생방안 검토 결과 107
5.5 소결 110
6. 매트기초 시공을 통한 성능 검증 111
6.1 서론 111
6.2 매트기초 시공 111
6.2.1 개요 111
6.2.2 매트기초 타설계획 113
6.2.3 수화열 계측계획 113
6.2.4 매트기초 콘크리트 타설 116
6.3 매트기초 시공 결과 120
6.3.1 매트기초 시공 품질관리 결과 120
6.3.2 수화열 계측 결과 123
6.3.3 시공상태 확인 결과 125
6.3.4 수화열 해석값과 실측값 비교 126
6.3.5 유사 현장 비교 128
6.4 소결 129
7. 결 론 130
참고문헌 132
국문초록 154Docto
응용언어학 L1 및 L2 연구 논문초록의 어휘다발의 구조 및 기능적 패턴과 수사학적 무브
No full textThis comparative study aims to explore connections between lexical bundles and rhetorical moves in international research article (RA) abstracts of applied linguistics and Chinese RA abstracts of applied linguistics. The two corpora used in this study were Native Research Article Abstract Corpus (NRAC) and Chinese Research Article Abstract Corpus (CRAC). The results show that Move 1 (Background) is an optional, while Move 2 (Purpose/Aim), Move 3 (Methods), Move 4 (Results and Discussions) and Move 5 (Conclusion) are identified as obligatory moves in the RA abstracts of applied linguistics. Data analysis shows that the RA abstracts of applied linguistics are mainly composed of VP-based bundles. Both international and Chinese RA writers have included these four moves in their RA abstracts. The results of data analysis indicate that RA abstracts in applied linguistics are mainly composed of VP-based bundles. Both L1 and L2 writers rely heavily on VP-based bundles when they write their journal paper abstracts. Data analysis in the functional distribution of frequent bundles in the five moves shows that research-oriented and stanceoriented bundles have connection to Move 1, research-oriented bundles to Move 2 and Move 3, text-oriented bundles to Move 4, and stance-oriented and text-oriented bundles to Move 5. The comparison of bundle usage in L1 and L2 writers shows that L2 writers used more lexical bundles when compared to L1 writers in terms of overall lexical bundle tokens. The comparison of structural categories of lexical bundles in L1 and L2 writer groups reveals that there are different preferences for syntactical categories of lexical bundles from Move 2 to Move 5. Compared to an L1 writer group, the results show that L2 writers use more VP-based, less PP-based bundles in Move 2, more VP-based and less NP-based bundles in Move 3, less NP-based and PP-based and more VP-based bundles in Move 4 and more PP-based an less VP-based in Move 5. The comparison of functional distribution of lexical bundles in the two corpora has found that, for bundle tokens, L2 writers have underused research-oriented bundles in Move 1, text-oriented bundles in Move 3, stanceoriented bundles in Move 5 and overused text-oriented bundles in Move 2, stanceoriented bundles in Move 4 and research-oriented bundles in Move 5. For bundle types in functional comparison of L1 and L2 writer groups, there are no differences in the first three moves except that L2 writers have underused stanceoriented bundles and text-oriented bundles in Move 3 in Move 5 and have overused research-oriented bundles in Move 5. As for bundle-move connections, this research has found that RA abstracts are mainly composed of VP-based bundles syntactically and text-oriented bundles functionally. The findings from this current study may provide, hopefully, a reference for academic writing instruction in English for Academic Purposes or English as Second Language. Applications and further research suggestions have also been discussed accordingly.Chapter 1 Introduction 1
1.1 Research background 1
1.2 Objectives of this study 3
1.3 Research questions 6
1.4 Significance of this study 6
1.5 Structure of this dissertation 8
Chapter 2 Literature Review 9
2.1 Lexical bundles 10
2.1.1 Definition of lexical bundle 10
2.1.2 Structural classifications of lexical bundles 12
2.1.3 Functional classifications of lexical bundles 14
2.1.4 Previous studies related to the present research 18
2.2 Research article abstracts and move analysis 19
2.3 Corpus-informed framework to phraseology 26
Chapter 3 Data and Methodology 29
3.1 Corpora of research article abstracts 29
3.2 Data resource and section criteria 30
3.3 Data processing procedure 32
3.4 Tools used in corpus-building 35
3.5 Analytic framework 38
3.5.1 Identification of lexical bundles 38
3.5.2 The structural classification of lexical bundles for this study 39
3.5.3 The functional classification of lexical bundles for this study 40
3.6 Corpus summary in statistics 41
Chapter 4 Results and Discussion 44
4.1 Moves patterns in NRAC and CRAC 44
4.1.1 Obligatory move and optional move in NRAC and CRAC 44
4.1.2 Move sequences in NRAC and CRAC 46
4.2 Target bundles, frequency,structureandfunctions of lexical bundles in research
article abstracts 48
4.2.1 Target bundles in NRAC and CRAC 48
4.2.2 Comparing top 50 bundles in NRAC with Hyland’s (2008) and Salazar’s
(2014) 55
4.2.3 Frequent lexical bundles in NRAC and CRAC 57
4.2.4 Distribution of lexical bundle syntactical categories in NRAC 59
4.2.5 Distribution of lexical bundle syntactical categories in CRAC 63
4.3 Comparison of syntactic pattern of lexical bundles in NRAC and CRAC 65
4.3.1 Overall distribution of syntactic categories across moves 65
4.3.2 Comparison of lexical bundle syntactic patterns in Move 1 70
4.3.3 Comparison of lexical bundle syntactic patterns in Move 2 72
4.3.4 Comparison of lexical bundle syntactic patterns in Move 3 75
4.3.5 Comparison of lexical bundle syntactic patterns in Move 4 77
4.3.6 Comparison of lexical bundle syntactic patterns in Move 5 80
4.4 Comparison of lexical bundle functions in NRAC and CRAC 83
4.4.1 Comparison of lexical bundle functional patterns in Move 1 84
4.4.2 Comparison of lexical bundle functional patterns in Move 2 86
4.4.3 Comparison of lexical bundle functional patterns in Move 3 87
4.4.4 Comparison of lexical bundle functional patterns in Move 4 89
4.4.5 Comparison of lexical bundle functional patterns in Move 5 91
Chapter 5 Conclusions and Implications 94
5.1 Summary of the major findings 94
5.2 Implications of this study 97
5.3 Limitations of this study 98
References 99
Appendices 106
Appendix A: List of bundles in NRAC and CRAC 106
Appendix B: Journal lists & samples of abstracts with tags 139
Appendix C: R codes used in the current study 141Docto