8090 research outputs found
Sort by
A Study on the Influence of Seafarers’ Job Satisfaction on Organizational Commitment and Turnover Intention : Is There Any Difference Between Pre- and Post-Millennials
No full textDue to the COVID-19 pandemic situation that occurred in December 2019, long-term boarding seafarers are increasing due to delays in replacement, and the satisfaction of crews on boarding life is gradually decreasing. In addition, there are concerns about the reduction of the size of the crew market due to the resignation of seafarers and transfer to other occupations.
This study investigated the influence of seafarers' job satisfaction factors on organizational commitment and turnover intentions, and examined whether there were any differences between millennials and pre-millennials. In order to achieve these research objectives, the existing research results on millennials, job satisfaction, organizational commitment and turnover intention were reviewed, and a research model and hypothesis were established to draw the research results. In order to verify the research hypothesis, the study subjects were seafarers working on commercial ships. A total of 431 questionnaires were distributed to the seafarers, and a total of 419 copies were used for the study, excluding 12 questions with inappropriate responses. The data analysis of this study used the SPSS 21.0 program, and frequency analysis and descriptive statistics were performed to determine the characteristics of the sample. For hypothesis testing, hierarchical multiple regression analysis was performed.
The characteristics of the sample are reclassified as age classification into millennials and pre-millennial generations, nationality classification into Korea and foreign countries, and boarding experience classification into less than 3 years and more than 3 years. and exploratory data analysis was performed to examine the differences in job satisfaction (empowerment, work environment, relationship, pay, performance appraisal), organizational commitment, and turnover intentions according to classification by generation, boarding experience, and nationality.
In this study, the job satisfaction factors of seafarers were classified into empowerment, work environment, relationship, pay, performance appraisal. The results of research analysis are summarized as follows.
First, among the factors of seafarer's job satisfaction, pay, empowerment, and work environment were found to have a significant positive (+) effect on organizational commitment. On the other hand, relationship did not significantly affect organizational commitment.
Second, among the factors of job satisfaction of seafarers, the work environment was found to have a negative (-) effect on the turnover intention, and the relationship were found to have a positive (+) effect on the turnover intention. It was found that pay, empowerment, and performance appraisal did not significantly affect on the turnover intention.
Third, seafarer's organizational commitment was found to have a significant negative (-) effect on the intention to turnover.
Fourth, as a result of comparing millennials and post-millennials, job satisfaction factors that influence the organizational commitment and turnover intention of millennials showed that as the organizational commitment increased in all generations, the turnover intention decreased. and There was no difference between generations. Based on the results of these studies, the shipping organization provides practical data that can reduce turnover by identifying the impact on job satisfaction, organizational commitment, and intention to turnover of seafarers. It is expected that the application of welfare and personnel policies will help reduce seafarer turnover.제1장 서 론 1
제1절 연구의 배경과 목적 1
제2절 연구 방법과 구성 3
제2장 이론적 고찰 5
제1절 밀레니얼세대 의의 5
1. 밀레니얼세대의 개념 5
2. 세대구분 5
3. 밀레니얼세대의 특징 7
제2절 선원의 업무와 역할 9
1. 선원의 개념 9
2. 선원의 특징 11
제3절 선원의 직무만족 14
1. 직무만족의 영향 요인 14
2. 직무만족의 개념 16
제4절 선원의 조직몰입 20
1. 조직몰입의 개념 20
제5절 선원의 이직의도 23
1. 이직 및 이직의도의 개념 23
2. 이직에 영향을 미치는 요인 25
제3장 연구모형과 가설의 설정 28
제1절 연구모형의 설계 28
제2절 연구가설의 설정 29
1. 직무만족 영향요인 29
2. 직무만족과 조직몰입과의 관계 29
3. 직무만족과 이직의도와의 관계 30
4. 조직몰입과 이직의도와의 관계 30
5. 밀레니얼 세대와 밀레니얼 이전 세대의 차이 31
제3절 변수의 조작적 정의와 측정 32
1. 직무만족 요인 32
2. 조직몰입 35
3. 이직의도 36
제4장 실증분석 37
제1절 연구의 설계 37
1. 자료의 수집 및 분석방법 37
2. 표본의 특성 37
3. 자료의 신뢰성 및 타당성 검토 45
제2절 연구가설의 검정 50
1. 가설의 검정 50
2. 가설 검정 결과의 해석 60
제5장 결 론 62
제1절 연구 결과 및 시사점 62
1. 연구결과의 요약 62
2. 연구결과의 시사점 64
제2절 연구의 한계 및 향후과제 66
참고 문헌 67
67
70
74
[부 록] 설문지 75
국문 초록 86Maste
소형 연안 선박용 연료전지 배터리 태양전지 하이브리드 시스템 적용에 관한 연구
No full textWith the effort put forward by the international maritime organization (IMO) to implement strict regulations and strategic plans to minimize the greenhouse gas gradually (GHG) emission and eradicate within the century at the earliest possible from the shipping industry, the current trend of more efficient ships have emerged. Subsequently, the birth of all-electric ships (AES) has been prominent. The utilization of an electric propulsion system replacing the conventional mechanical system is exceptionally essential. The integrated power system feature is vital, further integrating different power sources or energy storage systems into the marine power system. In this research work, a study is carried out on applying a fuel cell-battery-solar cell hybrid system for small coastal ships and investigating system performance and stability. Furthermore, estimation of each system space and weight is also conducted. Subsequently, an overall system model with the relevant control systems for each system is designed and developed in the MATLAB Simulink application. The system performance is analyzed for zero and dynamic solar power under dynamic vessel load conditions. The simulation results of each system demonstrate the effective operation of each system in a hybrid configuration while performing the appropriate defined functions. The overall system performance indicates a stable system operation where the system parameters vary within the allowable limits irrespective of the dynamic and transient conditions of the system. Moreover, each system's estimation of space and weight concerning its capacity is vital for vessel space optimization in a practical implementation approach.With the effort put forward by the international maritime organization (IMO) to implement strict regulations and strategic plans to minimize the greenhouse gas gradually (GHG) emission and eradicate within the century at the earliest possible from the shipping industry, the current trend of more efficient ships have emerged. Subsequently, the birth of all-electric ships (AES) has been prominent. The utilization of an electric propulsion system replacing the conventional mechanical system is exceptionally essential. The integrated power system feature is vital, further integrating different power sources or energy storage systems into the marine power system. In this research work, a study is carried out on applying a fuel cell-battery-solar cell hybrid system for small coastal ships and investigating system performance and stability. Furthermore, estimation of each system space and weight is also conducted. Subsequently, an overall system model with the relevant control systems for each system is designed and developed in the MATLAB Simulink application. The system performance is analyzed for zero and dynamic solar power under dynamic vessel load conditions. The simulation results of each system demonstrate the effective operation of each system in a hybrid configuration while performing the appropriate defined functions. The overall system performance indicates a stable system operation where the system parameters vary within the allowable limits irrespective of the dynamic and transient conditions of the system. Moreover, each system's estimation of space and weight concerning its capacity is vital for vessel space optimization in a practical implementation approach.1 Introduction 1
1.1 Background 1
1.2 Research Content 2
1.3 Thesis Outline 3
2 Fuel Cell Hybrid Power System for Marine Applications 4
2.1 Introduction 4
2.2 Fuel cell Hybrid power system 6
2.3 Fuel cell-Battery-Solar Cell Hybrid power system overview 7
2.3.1. Fuel Cell System 9
2.3.2. Battery System 13
2.3.3. Solar Cell System 15
2.3.4. Power Electronics Converters 21
2.3.5. Induction Motor with Field-Oriented Control Drive 26
3 Modeling of Fuel Cell-Battery-Solar Cell Hybrid Power System 28
3.1 Introduction 28
3.2 Fuel Cell System Model 28
3.2.1. Boost Converter with Controller 30
3.2.2. Fuel Regulator of Fuel Cell System 31
3.3 Battery System Model 31
3.3.1. Bi-directional Converter with Battery Controller 33
3.4 Solar Cell System Model 34
3.4.1. PV Array Block 34
3.4.2. Boost Converter with PV controller 36
3.5 3-phase Voltage Source Inverter (VSI) System 38
3.5.1. 3-phase Voltage Source Inverter (VSI) Model 38
3.5.2. 3-phase Voltage Source Inverter (VSI) controller 38
3.6 Vessel Load Profile 39
3.7 Power Management System 41
3.8 Simulation Model of Overall System 45
4 Analysis of Simulation Model Performance 46
4.1 Load Section 01 (150 kW) at SOC (70% → 40%) 46
4.2 Load Section 02 (250 kW) at SOC (15% → 45%) 46
4.3 Load Section 03 (500 kW) at SOC (20% → 60%) 47
4.4 Load Section 04 (500 → 0 kW) at SOC (80% → 50%) 48
4.5 Load Section 03 & 04 (500 → 0 kW) at SOC (40% → 10%) 49
4.6 Load Section 05 (350 kW) at SOC (30% → 60%) 51
4.7 Load Section 05 (350 kW) at SOC (10% → 40%) 51
4.8 3-phase Induction Motor Characteristic 52
4.9 Voltage Source Inverter Performance 52
5 Estimation of System Space and Weight Allocation 56
5.1 Introduction 56
5.2 Space and Weight Allocation for Fuel cell system with H2 Storage 57
5.3 Space and Weight Allocation for Battery System 59
5.4 Space and Weight Allocation for Solar Cell System 60
5.5 Summary 61
6 Discussion and Conclusion 63
6.1 Discussion 63
6.2 Conclusion 64
7 References 66Maste
-해구해사법원의 대한해운 사건 판결을 중심으로-
No full textSince China joined the New York Convention in 1987, international exchanges have increased and court judgments related to foreign arbitration also progressed. However, years of development have shown that the approval and enforcement of foreign arbitration courts are facing major problems due to the flaws in China's foreign arbitration and enforcement system. In general, litigation and arbitration procedures take a considerable time for judgment to be made by the courts and execution to be completed. If the losing party does not voluntarily fulfill the court's ruling, the winning party's rights may be protected by any compulsory execution. However, if the losing party escapes the property to avoid the execution of the court during the litigation or arbitration process or after the ruling is made, and then the ruling becomes ineffective. Therefore, in order to protect the status of the parties during litigation or arbitration and to ensure the enforcement power of the ruling, most countries give the court the power to issue a disposal authority and a temporary disposition to the arbitration division. In this paper, I reviewed the process of approving and enforcing China's overseas arbitration through the case of a dispute over a charter party between Korea Shipping and China Heahang Group. As a result, the Chinese Maritime Court approved the property preservation application filed by Korea Shipping to China Heahang Group during the hearing based upon approve and execute foreign arbitration, but the first approval was rejected later, and then it caused some problems in preserving the rights of Korea Shipping. To solve this problem, a study was conducted on the disposition of preservation during the hearing period for the approval and execution of foreign arbitration. Also this paper was to analyze the legislative status and legal practice of property preservation during the review period for approval and execution of foreign arbitration and to provide improvement measures to ensure that foreign arbitration courts are approved and executed in China. This paper briefly introduces the scope and grounds for China's approval and execution of foreign arbitration, followed by the meaning and characteristics of temporary disposition of the period during which foreign arbitration are approved and executed in China. The legal basis for the enforcement was described and compared to the temporary preservation disposition under the Chinese Civil Procedure Act, and finally, the legal basis for the preservation of property during the trial period for approval and execution of foreign arbitration courts. This paper first introduces China to the scope and grounds for approval and execution of foreign arbitration, and then describes the meaning, characteristics, and legal basis for the temporary disposition of foreign arbitration China. In addition, after a comparison with the provisional preservation disposition under the Chinese Civil Procedure Act, I proposed legal grounds for the preservation of property during the trial period for approval and execution of foreign arbitration.중국은 1987년 뉴욕 협약에 가입한 이래 국제 교류가 증가함에 따라 외국 중재판정과 관련된 법적 실무가 증가하였지만, 수년에 걸친 발전으로 볼 때 외국중재판정의 승인 및 집행은 중국의 외국중재판정 승인 및 집행 체계의 결함으로 인해 큰 문제에 직면해 있다.
소송 및 중재절차 모두 그 판결이 내려지고 집행이 완료되기까지는 상당한 시간이 소요된다. 만약 패소당사자가 판결을 자발적으로 이행하지 않는다면 강제집행을 통해 승소 당사자의 권리를 구제받도록 해야 할 것이다. 그러나 패소당사자가 소송 또는 중재가 진행되는 동안 또는 판결이 내려진 후 집행을 위한 심사가 진행되는 동안에 재산을 도피시킨다면 판결은 아무 실효성 없는 법률 문서가 되고 말 것이다. 그러므로 소송 또는 중재가 진행되는 동안에 당사자들의 지위를 보호하고 판결의 집행력을 보장하기 위하여 대부분의 국가는 법원에 보전처분 그리고 중재판정부에 임시적 처분을 내릴 수 있는 권한을 부여하고 있다.
이와 관련하여 본 논문에서는 중국이 해외 중재판정을 승인하고 집행하는 대표적인 사례인 대한 해운과 해항그룹 간의 선박 임대 계약 분쟁 사례를 예로 들어 대한해운이 외국중재판정의 승인 및 집행을 위한 심리기간 중 제기한 재산보전 신청에 있어서 중국 해구(海口) 해사법원이 허가 및 거부 결정 반복이유에 대한 분석과 외국중재판정의 승인 및 집행을 위한 심리기간 중 보전처분에 관한 연구를 진행한다. 중국이 외국중재판정의 승인 및 집행을 위한 심사 기간 중 임시 보전처분 중의 재산보전의 입법 현황과 법적 실무의 문제점을 분석하고, 이에 대한 개선책을 제시함으로써 중국에서의 외국중재판정의 승인 및 집행을 진행할 수 있도록 보장해주기 위한 것이다.
본 논문은 우선 중국이 외국중재판정의 승인 및 집행을 위한 적용 범위, 근거 등에 대해 간단히 소개하고 그 다음에 외국중재판정이 중국에서 승인되고 집행되는 기간의 임시 보전처분의 의미와 특징, 시행에 대한 법적 근거를 기술하여 중국 민사소송법 상의 임시 보전처분과 비교한 후, 마지막으로 외국중재판정의 승인 및 집행을 위한 심리기간 중 재산보전에 관한 개념 및 절차, 동의 여부에 대한 법적 근거를 제시하고자 한다. 대한해운과 해항그룹의 사례를 심층 분석하여 중국이 외국중재판정의 승인 및 집행 기간 중 재산보전제도 인정에 있는 문제점을 제시하고, 입법을 보완하는 차원에서 외국중재판정의 승인 및 집행을 위한 심리기간 중 재산보전을 신청할 경우 그와 관련된 법적 근거를 마련됨으로써 활동이 원활히 추진될 수 있도록 보완책을 제시하고자 한다.제1장 서 론 1
제1절 연구 목적 1
제2절 연구의 범위 및 연구방법 5
제2장 외국중재판정과 보전처분제도의 개관 7
제1절 외국중재판정의 중국에서의 승인 및 집행 개관 7
Ⅰ. 외국중재판정 중국에서의 승인 및 집행 개념 및 범위 7
Ⅱ. 외국중재판정의 승인 및 집행 근거 법률 10
Ⅲ. 외국중재판정의 승인 및 집행 절차 13
제2절 보전처분의 개관 16
Ⅰ. 보전처분의 개념 16
Ⅱ. 보전처분의 관할권 19
Ⅲ. 보전처분의 신청 절차 22
Ⅳ. 보전처분의 근거 법률 26
Ⅴ. 구분 개념으로서의 임시보전처분 29
Ⅵ. 보전처분에 관한 사법해석 및 분석 35
제3절 소결 40
제3장 대한해운사건의 중재판정의 승인 및 집행 신청에 관한 판결 분석 41
제1절 대한해운 사건의 개요 41
Ⅰ. 사건 배경 41
Ⅱ. 보전처분의 대한 신청 및 피신청인의 재심신청 42
Ⅲ. 법원의 최종 판결 44
제2절 판결 분석 46
Ⅰ. 소송절차에 의거한 재산보전 처분신청의 승인 46
Ⅱ. 국재협약으로서 재산보전 처분신청의 거부 47
제3절 외국 중재판정의 승인 및 집행을 위한 심리기간 중 보전처분 신청의 법률 근거 48
Ⅰ. 부정설 48
Ⅱ. 긍정설 51
제4절 소결 53
제4장 외국중재판정과 보전처분제도의 문제점 및 개선방안 56
제1절 중국법상 외국중재판정의 승인 및 집행과 보전처분에 관한 문제점 56
Ⅰ. 중재판정부의 보전처분 권한으로 인한 무효 발표 56
Ⅱ. 중재규칙과 중재법의 불일치 57
Ⅲ. 보전처분시 집행가능성(Enforceability)의 불확실성 58
제2절 보전처분제도의 개선방안 59
Ⅰ. 중재법의 개정 59
Ⅱ. 준거법률의 판단 기준을 완화 63
Ⅲ. 해사분쟁에 대한 보전처분에 관련 법률 활용 및 보완 67
Ⅳ. 소송법상 보전처분의 신청 승인 및 집행 조건의 명시 69
제3절 소결 74
제5장 결론 76Maste
심층 신경망 및 Range-Time-Doppler Map을 결합한 레이더 기반 사람 행동 인식
No full textHuman Activity Recognition (HAR) is a technology that recognizes behavior by collecting and interpreting information related to human motion using various sensors. HAR technology can utilize behavioral recognition information for the purposes of detecting various threats as well as monitoring health and behavior in daily activities. In particular, radar-based HAR has been intensively researched through the convergence of advantages such as contactless methods and personal information protection with rapidly developing deep learning (DL) technology.
Radar-based HAR using DL generally performs a preprocessing process that transforms a two-dimensional (2D) doppler spectrogram through short-time Fourier transform (STFT) to express the speed of the human body and limbs. However, in the process of converting to a 2D doppler spectrogram, information on the time-Doppler (TD) change according to each range is lost. In addition, there is a problem in that the reliability of the recognition accuracy is insufficient because the environment used in practice is very vulnerable to the effects of changes in geometrical structure and human information different from the learned data.
To overcome these problems, this thesis proposed a new radar-based HAR that combined range-time-Doppler (RTD) map and range distributed (RD)-DL model to improve generalization performance and utilize lost information for TD. Unlike TD maps, which are mainly used for radar-based HAR, the proposed RTD map extended radar information in 3D according to range, which provided detailed key features related to human activities. Also, the proposed RTD map attempted to improve the performance by using continuous wavelet transform (CWT) in the time domain with the TD maps expressing the spectrogram. CWT is a structure in which the size of the window changed to analyze the discontinuous part of the signal. Therefore, it delivered more diverse features to the RD-DL model than STFT, which performed analysis with a fixed window on the original signal. However, in the 3D RTD map, since human activity was not determined by the range, there was a trade-off that causes overfitting. Therefore, the proposed RD-DL model learned by concentrating only on information about the TD by configuring the 3D RTD map as an independent neural network according to the range. Therefore, the proposed RD-DL model was robust against changes in geometry and human information because it inferred human behavior by considering only velocity changes.
In addition, I applied the wasserstein generative adversarial network-gradient penalty (WGAN-GP) to generate an TD map to augment the training dataset. When trained through the WGAN-GP, it was easy to generate large amounts of similar data with the same distribution as the original data. These generated fake micro-Doppler (MD) images were applied in the training process of the RD-DL model to improve the learning performance.
To verify the performance of the proposed model, experiments were conducted using the University of Glasgow’s “Radar signatures of human activities”, which is an open dataset for radar-based HAR research. The results of comparing the proposed model and CNNs with the same number of parameters demonstrated that higher recognition accuracy was achieved. Additionally, the recognition error was lowered with different structures, the proposed system showed to be robust against the change in geometry and human information.Chapter 1. Introduction 1
1.1 Background and Necessity for Research 1
1.2 Objectives and Contents for Research 6
Chapter 2. Radar-based HAR and Deep Learning Model 10
2.1 FMCW Radar 10
2.1.1 Basic Architecture of Radar 10
2.1.2 Pre-Processing for FMCW Radar-based HAR 15
2.2 Deep Learning Model 20
2.2.1 Convolutional Neural Network 20
2.2.2 Recurrent Neural Network 21
2.2.3 Generative Adversarial Network 25
2.2.4 Deep Learning Approaches for HAR in Radar 28
Chapter 3. Proposed Radar-based HAR Systems 31
3.1 Overall Proposed RTD-based HAR System 31
3.2 RTD Processing 32
3.3 RD-CNN for radar-based HAR 38
3.4 RD-CNN-LSTM for radar-based HAR 42
3.5 Integrating Range Guidance for HAR System 44
3.6 Radar Image Generation using CWT-based WGAN-GP 45
Chapter 4. Experiment Environments 49
4.1 Dataset 49
4.2 Evaluation 50
4.3 Training environment 52
Chapter 5. Results and discussion 53
5.1 Data analysis 53
5.2 Experimental Results 60
Chapter 6. Conclusion 78
Reference 81Docto
블록단위 선적계획 자동화와 라싱포스 예측을 중심으로
No full textThe stowage planning in containership becomes crucial to optimize the shipping logistics supply chain but complexity of it becomes very high especially for large containership like over 15,000 TEU. The quality of stowage varies from the level of skill of stowage planners, and it impacts a lot to the profit and loss. To overcome the problem, there were many studies in this field for the stowage automation but none of them becomes commercialized due to the NP-Complete problem. This study defines the process of stowage planning automation and its evaluation criteria and builds two different deep learning models - one is the Block Stowage and another is Lashing Force prediction. The Reinforcement Learning is used for Block Stowage to allocate stowage spaces for multiple ports and the Supervised Learning is studied for Lashing Force prediction which is one of the most important aspects in terms of cargo safety as well as utilization, especially for large containership such as more than 10,000 TEU. It is a challenge for stowage planners when large containerships are in the last port of region because mostly the ship is full and the stacks on deck are very high. This study also conducts training and testing the models and provides the results in comparison with stowage planning tool.제 1 장 서 론 1
1.1 연구의 배경 및 필요성 1
1.1.1 컨테이너선 운임 현황 1
1.1.2 컨테이너 선박의 대형화에 따른 선적계획의 복잡도 증가 2
1.1.3 선적계획의 중요성 3
1.1.4 인공지능 기반 선적계획자동화 연구의 필요성 5
1.2 연구 방법 및 구성 6
제 2 장 관련 문헌 연구 7
2.1 선적계획 (Stowage Planning) 연구 7
2.1.1 선사 선적계획 연구 10
2.1.2 터미널 선적계획 연구 11
2.2 인공지능을 활용한 선적계획 연구 13
2.3 인공지능을 활용한 선적계획자동화 연구의 배경과 차별성 14
2.4 선적계획시스템 15
제 3 장 선적계획의 이해 및 자동화 정의 19
3.1 컨테이너 및 컨테이너 선박의 이해 19
3.1.1 컨테이너 19
3.1.2 컨테이너 선박 22
3.2 선적계획의 이해 23
3.2.1 물리적인 컨테이너 선적 패턴 24
3.2.2 크레인인텐서티의 정의 및 영향을 주는 하역방식 24
3.2.3 규격외화물 선적계획 27
3.2.4 위험화물 선적계획 27
3.2.5 최대적재중량(Stack Weight) 제약 28
3.3 선적계획 평가항목 및 프로세스 식별 29
3.3.1 선적계획의 평가항목 29
3.3.2 선적계획 프로세스 32
3.3.3 선사 선적계획과 터미널 선적계획의 차이점 35
3.4 선적계획자동화 프로세스 분류 36
3.5 선적자동화를 위한 라싱 연구의 필요성 38
제 4 장 블록단위 선적계획(Block Stowage) 자동화 40
4.1 블록단위 선적계획 자동화를 위한 식별사항 40
4.1.1 블록(Block) 40
4.1.2 크레인인텐서티(Crane Intensity) 41
4.1.3 가로경사(Heeling) 42
4.2 강화학습을 이용한 블록단위 선적계획 자동화 43
4.2.1 강화학습 프레임워크와 선적계획 43
4.2.2 강화학습 알고리즘 44
4.2.3 강화학습을 위한 상태, 행동 및 보상의 정의 48
4.3 컨테이너 물량 할당 평가 51
4.3.1 초기 학습데이터 51
4.3.2 실험의 정의 및 목표 51
4.3.3 환경(Environment)에서 상태(State) 및 보상(Reward)의 정의 52
4.3.4 네크워크 모델링 53
4.3.5 학습 결과 53
4.3.4 검증 결과 54
4.3.5 결과 평가 55
4.4 결과논의 56
제 5 장 인공지능을 이용한 라싱포스 예측 58
5.1 선적계획에서의 라싱 58
5.1.1 라싱의 이해 58
5.1.2 라싱브리지(Lashing Bridge)의 이해 59
5.1.3 라싱 패턴의 이해 59
5.1.4 라싱포스의 이해 61
5.1.5 선박 대형화에 따른 라싱의 중요성 61
5.1.3 선적계획자동화에서 라싱포스 예측의 필요성 63
5.2 프로세스 및 인공지능을 이용한 예측 아이디어 64
5.2.1 라싱포스 해결 프로세스 64
5.2.2 인공지능을 이용한 라싱포스 예측 아이디어 65
5.3 Multi-modal 딥러닝을 이용한 라싱포스 예측 66
5.3.1 예측 모델을 활용한 선적계획 프로세스 66
5.3.2 라싱포스 예측 모델 구축, 학습, 검증 및 결과 평가 67
5.4 결과논의 79
제 6 장 결론 80
참고문헌 82Docto
전달경로분석을 적용한 함정용탑재장비의 고체음 예측에 관한 연구
No full textIn general, structure borne noise(SBN) causes various vibration problems in machinery and structures. SBN is vibration or noise generated at the receiving point due to source induced vibration or noise transmitted through transfer path.
In case of naval shipboard equipment, it must meet higher standards than equipment manufactured by general production process. This is to ensure stability and reliability of the ship and the equipment, and also to ensure airtightness of underwater radiation noise. Thus, the double mounting systems are often used and in this case, according to MIL-STD--740-2, the measuring position of SBN is at the upper surface of the base frame, and must meet the acceptance criteria.
In general, for double mounting system the mounting equipment and the base frame are modeled as rigid bodies, and the type of mount, the installation location, and the size and weight of the base frame are designed as rigid mode of the low frequency band. The required frequency range of SBN of MIL-STD-740-2 is up to 10kHz, and SBN is highly affected in this range by flexible mode of the base frame. Therefore, SBN prediction should done in different point of view.
In order to predict the SBN of the base frame using forced vibration analysis, it is necessary to analytically calculate or measure the frequency response function(FRF) and the excitation force of the base frame.
First, for directly measuring the FRF method, it is difficult to excite up to 10kHz, which is the standard of MIL-STD-740-2. Therefore, finite element analysis(FEA) is used to obtain FRF up to 10 kHz. In order to obtain a high-precision FRF by FEA, detailed data of the entire system, such as the dynamic characteristics of the on-board equipment, base frame, and upper and lower mounts, and accurate excitation force must be provided. However, detailed data on ship payload equipment is difficult to obtain due to the military secrets.
Therefore, there is a need for a practical method of calculating FEA without detailed data of the upper elements of the base frame. Because the SBN of the base frame is up to high frequency, it is expected that the flexible mode of the base frame will have much influence. It is also expected that the dynamic characteristics of the upper elements of upper mounts to have little effect on the base frame.
This study proposes a method to obtain the FRF only for the base frame, ignoring the upper elements of base frame. Also, this study confirms the validity of analysis method by comparing measured FRF of the base frame with and without the upper elements.
As a result, the FRF of the base frame with or without upper elements marginally differs in the low-frequency region of the rigid body mode, and the difference in high-frequency region of the flexible body mode is negligible. Therefore, for SBN analysis, even if the upper elements of the base frame are ignored and only the base frame is analyzed, it is judged that SBN can be predicted without having significant differences compared to the analysis results that consider upper element.
Second, it is a method for calculating the excitation force acting from the upper mount to the base frame. The transfer path analysis(TPA) is a method of calculating the excitation force by expressing the relationship between the force of the source and the vibration of the receiver. This is especially useful when the actual vibration mechanism is too complex to be modeled or measured directly.
Using the measured SBN according to MIL-STD-740-2 and the calculated FRF of base frame by FEA, the excitation force transmitted from the upper mount to the base frame is calculated using matrix inversion method of TPA. Then the SBN is calculated by applying the excitation force obtained by TPA with the FRF of base frame calculated by FEA. By comparing and reviewing the measured SBN and calculated SBN, the validity of the method of calculating the excitation force by the TPA is confirmed. Also, it is confirmed that the predicted SBN satisfy the MIL-STD-740-2 standard only by changing the shape of the base frame without changing the excitation force or the mount dynamic characteristics.
In the future, to improve the accuracy of calculation through reliable modeling and excitation force calculation for various models, it is necessary to measure FRF and predict SBN for various types of naval shipboard equipment. Based on this principle, continuous research on optimal design of base frame for SBN is required.제1장 서 론 1
1.1 연구의 배경 1
1.2 연구의 목적 및 내용 5
1.3 논문의 구성 9
제2장 구조물의 고체음 예측 이론 10
2.1 유연체(다자유도계)의 주파수응답함수 11
2.2 전달경로 분석에 의한 기진력 계산법 17
2.2.1 직접 기진력 측정법 19
2.2.2 마운트 강성법 19
2.2.3 행렬반전기법 21
2.3 기진력을 적용한 고체음 예측법 28
제3장 베이스프레임의 주파수응답함수 계산 29
3.1 베이스프레임 상부요소 배제 가능성 검토 30
3.1.1 상부요소 제거 전·후의 주파수응답함수 측정 33
3.1.2 상부요소 제거 전·후의 실험모드해석 결과 37
3.1.3 베이스프레임의 상부요소 배제 가능성 검토결과 53
3.2 베이스프레임의 주파수응답함수 유한요소해석 55
제4장 베이스프레임에 작용하는 기진력 계산 67
4.1 베이스프레임의 고체음 측정 68
4.2 전달경로 분석을 이용한 기진력 계산 77
4.3 베이스프레임의 고체음 계산 및 검토 89
제5장 구조변경 베이스프레임에 대한 고체음 예측 98
5.1 구조변경 모델들에 대한 주파수응답함수 유한요소해석 99
5.2 구조변경 모델들에 대한 고체음 예측 107
5.3 구조변경 모델들에 대한 고체음 검토 123
제6장 결 론 132
참 고 문 헌 135Docto
Evaluation of Vibration Control Performance of Tuned Mass Damper in Building Structures
No full text건축구조물에 다양한 동적 하중이 작용하면 구조물이 진동하여 구조물의 안전성이나 거주자의 사용성에 문제가 발생한다. 이를 해결하기 위한 방안으로, 구조물의 진동을 제어하여 구조물의 안전성과 거주자의 사용성을 확보하기 위한 다양한 형태의 진동제어장치가 개발되고 있다. 진동제어장치는 진동제어방식에 따라 수동제어, 능동제어, 준능동제어, 복합제어로 구분된다. 4가지 진동제어장치 중 수동제어시스템은 일반적으로 전력수급이 자유롭고 시스템이 단순하여 많이 사용되며, 특히 수동제어시스템 중 TMD(Tuned Mass Damper)가 주로 사용된다. TMD는 가이드 레일형과 진자형으로 구분되며 국내에서는 공간의 제약이 적은 가이드 레일형이 주로 적용된다. 본 논문에서는 가이드 레일형 TMD의 마찰력으로 인한 문제점을 지적하고 이를 해결하기 위하여 Mass-Spring System TMD를 제안하였으며, 축소 모형 진동실험 및 수치해석으로 진동제어성능을 평가하였다. 축소 모형 진동실험을 통해 Mass-Spring System TMD 설치 전후의 최대 가속도와 RMS 값을 비교하여 진동제어성능을 검증하였다. 실제 건축구조물에서 진동실험을 수행하기에는 어려움이 있어 수치해석으로 이를 대신하였다. 수치해석 대상 구조물이 고층 구조물이므로 Mass-Spring System TMD의 질량이 구조물에 미치는 영향을 고려하여 질량비를 6가지로 구분하여 수치해석을 수행하였다. Mass-Spring System TMD의 진동제어성능은 조화 하중에 대한 시간 이력 해석을 수행하여 질량비에 따른 Mass-Spring System TMD 설치 전후의 최대 가속도와 RMS 값을 비교‧분석하여 검증하였다. 고층 구조물의 경우 구조물 자체의 질량이 크므로 Mass-Spring System TMD의 질량이 구조물에 미치는 영향을 최소화할 수 있도록 적절한 질량비를 선택해야 한다. 따라서 6가지 질량비 중 ISO 10137에서 허용하는 가속도 기준을 만족하는 최소 질량비를 선정하기 위하여 사용성 평가를 수행하였으며, 일련의 과정을 통해 Mass-Spring System TMD의 실효성을 입증하였다.1. 서론 1
1.1 연구배경 및 목적 1
1.2 연구동향 5
1.3 연구내용 및 방법 7
2. 이론적 배경 8
2.1 진동제어시스템 8
2.2 TMD(Tuned Mass Damper) 11
3. Mass-Spring System TMD 13
3.1 Mass-Spring System TMD 13
3.2 진동실험 개요 15
3.3 사전 계측 17
3.3.1 사전 계측 개요 17
3.3.2 동적 특성 추출 20
3.4 Mass-Spring System TMD 설계 25
3.5 진동실험 28
3.6 소결 32
4. Mass-Spring System TMD의 진동제어성능 평가 33
4.1 개요 33
4.2 Mass-Spring System TMD 모델링 35
4.3 입력 하중 39
4.4 Mass-Spring System TMD 진동제어성능 평가 41
4.5 사용성 평가 47
5. 결론 51Maste
A study on modeling of a ship’s propulsion system for digital-twin construction
No full textIn this manuscript, a mathematical model on the propulsion system of a ship for the development of digital-twin ship platforms that are key technology for operating ships in digital space is proposed.
Real-time continuous and variable data such as pressure variations of the engine and the crank angles, and the temperatures obtained from the actual ship were used for the proposed mathematical model.
In order to simulate accurately the combustion process occurring in the marine diesel engine of the propulsion system, the conventional four-stroke engine cycles consisting of suction, compression, explosion, and exhaust, were considered as 5 processing cycles in this study, such as suction, compression, explosion, expansion and exhaust. That is, the expansion process has been considered additionally.
The MATLAB Simulink has been used to construct the proposed digital model considering the time scale.
operating conditions of the fuel injection system and the load of the propulsion system were also simplified. The process of the fuel injection was considered as time-dependent mass changes during fuel boosting in which the opening of the injection valve was operated at a certain preset pressure, eventually completing the combustion physics in the engine cylinder.
The calculated data that show the relations between the pressure and the crank angle, and the temperature and the crank angle, showed good similarity with those obtained from the actual engine running, though there was a slight discrepance. It seems that the discrepance can be largely reduced if more time consecutive data can be obtained from long period of engine operations.
It was confirmed that real-time data processing was possible by changing the amount of angular acceleration in real time by the time-dependant digital data.
It has been verified that the comparison error between the actual ship test data and the digital model was measured as 0.8% ~ 4.2% under low speed and no-load conditions.제1장 서 론 1
1.1 연구배경 및 목적 1
1.2 연구의 구성 4
제2장 모델링 적용 이론 5
2.1 엔진·제너레이터 적용 이론 5
2.1.1 열·일 역학 지배방정식 5
2.1.2 Rate of Heat Release & Double Vide Model 11
2.1.3 Volumetric Model 17
2.2 엔진축계 모델링 적용 이론 18
2.2.1 크랭크 각도에 따른 토크변동 18
2.2.2 토크 조건에 따른 엔진 회전수 변화 20
제3장 디지털 모델 구성 및 가동결과 21
3.1 동력부 모델 구성 21
3.1.1 엔진 작동 성능 블록구성 23
3.1.2 엔진 구성요소 작동상태 블록구성 24
3.1.3 연소실 작동 상태 블록구성 26
3.1.4 동력부 작동 결과 46
3.1.5 실시간 토크 변동 가상 테스트 54
3.2 연료분사 모델 구성 56
3.2.1 연료 고압 부스터 분사 밸브구성 56
3.2.1 연료 분사결과 64
제4장 결론 및 고찰 65
참고 문헌 67Maste
A Study on the System and Sustainability of House Repair Project (Residential welfare project: payment of repair costs)
No full text2019년 기준 전국 30년 이상 노후화된 단독주택 가구 수는 약 250만호에 다다르고 있다. 이에 따라 정부 각 부처에서는 집수리와 관련된 여러 사업들이 진행되고 있다. 그 사업의 예시로는 행복마을, 새뜰마을사업, 슬레이트 지붕철거사업 등 다방면으로 많이 진행되어 왔고 앞으로도 많은 수요가 있을 것으로 예측되고 있다.
그중에서 LH가 진행하고 있는 수선급여사업에 대해서 살펴보려고 한다. 수선급여사업은 주거가 불안정한 저소득층의 주거수준을 높이기 위해 낡은 정도에 따라 맞춤형으로 주택을 보수하는 사업이다. 이 사업을 살펴보기 위해서는 2가지 측면으로 바라볼 필요가 있다
첫 번째, 수선유지 급여사업은 수급자를 대상으로 하는 사업이다. 사업을 진행하기 전 수급자 판단, 집의 소유자 판단, 주택노후도 등의 판단을 하여 결정된 후 집수리 사업자(자활업체)가 집수리를 진행한다. 이 과정에서 조사기관과 수행기관의 의견차이로 인한 수혜자들의 불만, 제도적으로 부족하여 겪는 시행자들의 어려움 등이 발생하여 최종적으로 집수리가 진행되었던 집들이의 만족도가 전체적으로 높지 않다.
두 번째, 수선유지 급여사업의 시행은 지역의 자활업체가 담당한다. 자활업체의 생태계, 구조 등을 보았을 때, 대다수의 자활업체는 선행연구에서 언급하고 있는 사회적영역의 한축을 담당하는 영역까지 성장하지 못할 가능성이 높다. LH 역시 매해 수선급여사업을 자활업체에게 배분하고 있지만, 이 또한 자활업체의 성장보단 생존에 그 의의가 있다. 그렇기 때문에 수선유지 급여사업의 공사 품질 및 만족도가 올라가지 못하고 있다.
그동안 진행되었던 집수리사업에 대한 연구는 전제적인 방향성에 대한 연구와 수혜자들의 제도 개선에 대한 내용을 제언하는 것이 중점적으로 진행되어왔다.
본 연구에서는 수선유지 급여사업의 만족도 및 공사의 품질에 문제를 끼친 부분을 도출하여 향후 이 사업이 원활하게 진행하는 방안과, 집수리사업 등 국가사업에 참여중인 성장가능성이 있는 소수의 자활업체가 더 잘 성장하여 지역에 잘 정착할 수 있는 자활업체의 지속가능성을 중점적으로 살펴보고 그에 따른 방안을 제시하는 것에 그 목적이 있다.1. 서 론 1
1.1 연구의 배경 및 목적 1
1.2 연구의 내용 및 범위 2
2. 집수리사업의 이론적 고찰 3
2.1 집수리사업 3
2.1.1 집수리사업 개요 3
2.1.2 집수리사업 현황 4
2.1.3 수선유지 급여사업 11
2.2 선행연구 고찰 16
2.2.1 집수리사업 관련 선행연구 16
3. 자활기업의 지속성에 관한 이론적 고찰 19
3.1 자활기업 개요 19
3.2 자활기업의 지속성에 관한 선행연구 21
3.3 자활기업의 지속성을 위한 연계사업 24
3.3.1 도시재생 뉴딜사업 마을관리협동조합 24
3.3.2 터새로이 사업 28
3.3.3 도시재생기업(CRC) 29
3.3.4 관련 선행연구 및 소결 34
4. 분석의 틀 및 분석결과 36
4.1 분석의 틀 : FGI 설문조사 36
4.1.1 설문조사 개요 36
4.1.2 FGI 설문 문항(분석의 틀) 및 진행방법 36
4.1.3 설문조사 결과 40
4.2 회귀분석 51
4.2.1 회귀분석 개요 51
4.2.2 분석방법 51
4.2.3 분석결과 53
4.3 분석결과 73
4.3.1 분석 최종결과 73
5. 결론 76
5.1 연구의 결과 및 의의 76
5.2 연구의 한계점 및 향후 연구과제 77
부록 78Maste
Behavior Analysis on Earthquake-Induced Deformation of Silty Sand Soil to Drainage Condition
No full textIn this study, laboratory tests were conducted to analyze the physical and mechanical properties of silt, silty sand and sand soils in Saemangeum and Incheon areas, where are expected to build large-scale facilities by dredging and reclamation in Korea.
The soil physical properties of Saemangeum area were analyzed as water content 25.8~30.8%, specific gravity 2.60~2.68, initial void ratio 0.682~0.825, uniformity coefficient 6.6~22.3, coefficient of curvature 1.4~4.5, and 12~72% of fine contents ratio. Physical properties of Incheon soil show water content 8.0~10.6%, specific gravity 2.62, initial void ratio 0.209~0.278, uniformity coefficient 7.3~12.2, coefficient of curvature 0.7~0.9, and 7.6~8.1% of fine contents ratio.
In order to determine the liquefaction cyclic resistance ratio of soils sampled from Saemangeum and Incheon areas, cyclic triaxial tests were conducted. In the case of silt, the cyclic resistance ratio(CRR) was 0.176~0.205, CRR=0.179~0.225 for silt sand, and 0.203~0.216 for sand. According to test results, in the case of silt samples with a large amount of fines including clay, it was found that the number of loading cycles required to reach liquefaction at the same relative density was less than the sample that did not. In other words, in the case of a sample with a large content of fines, it reaches the liquefied state in a short time. However, the silty sand samples with a some amount of fines including small amount clay delayed the time to reach the liquefied state. The reason for the increase in the liquefaction Cyclic Resistance Ratio(CRR) is that the amount of clay particles is small, which results less effect the decrease of permeability and frictional resistance between particle. A similar trend was also observed for sand, which does not contain clay.
In the case of Saemangeum area composed of silt and silt sand with a large content of fines, it was analyzed as undrained drainage condition during earthquake. In the case of Incheon area composed of large amount of sand was analyzed by FEM as a drained drainage condition to figure out the behavior after the earthquake. For Saemangeum area, the excess pore water pressure ratio(EPWPR) during earthquake was 0.7. For Incheon are, the excess pore water pressure ratio was found to be 0.3. It was confirmed that both areas were not reached liquefaction state, but only partial liquefaction were reached. In Saemangeum area, the drainage condition of the ground was analyzed as undrained. In this case, the horizontal displacement occurred largely at the point where the surcharges load was small, and in the order of the front part of the structure, the structure, and the landfill site. The maximum displacement was observed in the short-period earthquake and the smallest displacement in the domestic earthquakes. It was found that the front of the structure was swelled due to the settlement of the substructure under the structure. It was interpreted that the maximum settlement occurs in the short-period earthquake and the minimum it in the domestic seismic.
In the Incheon area analyzed by drainage conditions, it was found that the excess pore water pressure generated during the earthquake gradually dissipated after the earthquake, resulting in additional horizontal and vertical (settlement) displacements. In the normal and reverse fault earthquake, short-period and artificial seismic, the maximum settlement occurred during an earthquake, and the domestic seismic earthquake showed that the minimum settlement occurred during an earthquake. After the earthquake, it was found that additional displacement due to the dissipation of excess pore water pressure occurred in all seismic waves. At all points, long-period seismic dissipate late in the excess pore water pressure after the earthquake. It was found that about 50% of the total settlement at some points of the long-period earthquake occurred as a result of the dissipation of excess pore water pressure after the earthquake. Therefore, it is necessary to continuously study the ground behavior that occurs as the excess pore water pressure is dissipated after the earthquake.1. 서 론 1
1.1 연구배경 1
1.2 연구목적 3
1.3 연구내용 및 범위 5
2. 이론적 배경 6
2.1 액상화 현상 6
2.2 액상화 발생 영향인자 7
2.2.1 상대밀도 7
2.2.2 입도분포 8
2.2.3 세립분의 함유량 9
2.2.4 유효연직하중 11
2.2.5 재하진동수 11
2.2.6 포화도 12
2.2.7 과압밀비 13
2.3 지진시 과잉간극수압 변화 14
2.4 지진 이후 과잉간극수압의 소산 17
3. 반복삼축압축시험 20
3.1 연구 대상지역 선정 20
3.1.1 새만금 지역 20
3.1.2 인천 지역 21
3.2 토질특성 분석 22
3.2.1 물리적 특성 22
3.2.2 역학적 특성 25
3.3 반복삼축압축시험의 원리 및 절차 27
3.3.1 시험개요 27
3.2.2 시험장치 28
3.3.3 해석원리 29
3.3.4 시험절차 33
3.4 시험결과 및 분석 34
3.4.1 반복횟수에 따른 축변형률과 과잉간극수압 분석 34
3.4.2 액상화 저항응력비(Cyclic Resistance Ratio, CRR) 61
4. 지반의 배수조건별 지진시 거동분석을 위한 해석방법 71
4.1 개요 71
4.2 입력지진파 72
4.3 수치해석방법 75
4.3.1 FLIP 모델 이론 75
4.3.2 요소시뮬레이션에 의한 FLIP해석에서 액상화 파라미터산정방법 84
4.3.3 액상화 파라미터 87
5. 지반의 배수조건에 따른 지진 시 및 이후 지반거동 분석 93
5.1 수치해석 모델 93
5.2 수치해석을 위한 입력파라미터 98
5.3 액상화 파라미터 결정 102
5.3.1 비배수조건 102
5.3.2 배수조건 103
5.4 수치해석 결과 분석 106
5.4.1 과잉간극수압비 분포 및 액상화 평가 106
5.4.2 지진시 지반거동 분석 119
6. 결론 148
참고문헌 151Docto