시스템 다이내믹스 기반 해양구조물 FEED 검증 방법에 관한 연구

황존규 목포해양대학교대학원 2021 국내박사

해양구조물에 대한 세계의 수요는 에너지 수급 메카니즘에 의해 결정되고, 세계 에너지 수요는 세계 경제 성장과 밀접하게 연관되어 있다. 즉, 세계 경제 성장에 따라 해양구조물에 대한 수요가 영향을 받고, 보다 직접적으로는 유가와 원유 생산량에 따라 수요가 변화한다. 이러한 원유의 생산은 육상 유전의 시추가 성숙 단계에 있는 반면 해양의 유전 개발은 성장 단계에 있기 때문에 장기적으로 시장이 매우 밝다고 볼 수 있어 개발의 필요성이 높다. 전통적으로 한국의 조선 해양산업은 타 경쟁국에 비하여 건조 기술에서 우위를 점하고 있지만, 해양구조물 설계기술의 핵심인 엔지니어링과 FEED 기술이 부족하고, 특히 개념설계와 기본설계 그리고 FEED의 역량은 매우 부족한 실정이다. 따라서 이러한 해양구조물 FEED 분야의 역량을 높이기 위해서 본 연구에서는 시스템 다이내믹스를 기반으로 하여 해양구조물 탑사이드 장비인 분리시스템(Separation System)을 대상으로 FEED 검증 방법에 관한 연구를 수행하였다. 해양구조물 분리시스템은 부가가치 측면에서 EPC(Engineering, Procurement and Construction) 프로젝트의 성공 여부를 결정할 수 있는 탑사이드(Topsides)의 가장 중요한 시스템 중 하나이다. 그럼에도 불구하고, 초기설계 단계에서 설계검증(Design Verification)에 대한 지금까지의 실태는 설계 작업의 진행이나 도면작성 및 제공에 국한되어 있어 초기설계(FEED;Front End Engineering Design) 과정에서 설계검증의 미흡으로 인하여 계약 후 잦은 설계변경에 의한 추가손실이 발생 되어왔다. 이러한 맥락에서 본 연구는 해양 구조물의 전체 프로젝트 수행 기간에 성공적인 사업수행을 도모하고 추가손실을 줄이고자 FEED 검증모델을 구축하여 시뮬레이션 후 그 결과를 현업에 적용하도록 하였다. 또한, 계약 전에 필히 FEED 검증을 수행하고 계약 후 상세설계 수행 시 설계변경이 최소화될 수 있도록 검증모델을 적용하였다. 제안된 설계검증 방법은 상세설계의 효과적인 실행뿐만 아니라 초기설계 단계에서 기술적 오류나 불일치 사항을 미리 찾아냄으로써 해양구조물의 엔지니어링, 구매조달 및 건조에 대한 경쟁력을 향상시키는 데 기여 할 것으로 예상한다. 이를 위하여 본 연구에서는 첫째, 시스템 다이내믹스의 인과요인 분석을 통하여 해양구조물 FEED 검증 방법을 구현하고자 FPSO 상부구조의 분리시스템(Separation System)을 대상으로 설계검증 모델을 적용하였다. FPSO는 부유식 원유 생산/저장/하역하는 해양구조물로서 시추선에 의해 개발이 완료된 유정과 연결하여 원유를 뽑아 올려 1차 분리 과정을 거친 후 Hull의 Cargo Hold에 저장했다가 유조선에 옮겨주는 역할을 한다. 이는 크게 선체 부분(Hull)과 상부구조(Topsides)로 나눌 수 있고 상부구조에 연구대상인 분리시스템이 위치 하고 있다. 또한, 분리시스템의 설계검증 방법으로는 설계단계에서 문제의 정의와 설계검증의 변수 선정, 인과지도 작성 및 적용 그리고 타당성 검증 순으로 프로세스를 진행하였다. 인과지도 작성은 논리 분석 능력이 우수한 Vensim PLE를 이용하여 수행하였고 모델 구축에 필요한 정보는 FEED Data에서 Operation Condition을 얻었으며 Hysis Simulation Data에서 Fluid Composition 자료를 얻었고 Vendor Data에서 설계 요구사항(Design Requirement)을 얻어 적용하였다. 둘째, 시스템 다이내믹스를 기반으로 저유량도 상관성 분석에 의한 새 로운 설계검증 모델(OC-Model)을 구현하였다. 특히, 해양구조물 공사 시작 단계에서부터 운전 조건을 고려하여 FEED에 대한 설계검증을 수행하여 조기에 설계 문제를 해결하고 계약 후 설계변경이 감소할 수 있도록 시도하였다. 제안된 설계검증 방법은 상세설계의 효과적인 실행뿐만 아니라 초기설계 단계에서 기술적 에러나 불일치 사항을 미리 찾아냄으로써 해양구조물의 엔지니어링, 조달 및 건조에 대한 경쟁력을 향상시키는 데 기여 할 것으로 예상한다. 결과적으로, 제안된 설계검증 방법이 해양구조물의 다른 핵심장비에도 확대 적용될 수 있으며, 향후 해양 프로젝트의 성공적인 수행에 의한 이익창출을 도모할 수 있을 것이다. 또한, 해양구조물 건조 시 설계변경에 의한 막대한 손실을 최소화 할 수 있을 것으로 기대한다. 결론적으로 본 연구를 통해서 첫째, 설계 오류를 조기에 찾아낼 수 있도록 하였고 둘째, 초기 설계검증에 의한 설계변경을 최소화 할 수 있도록 하였으며 셋째, 짧은 기간 내에 설계검증을 수행하여 입찰에 임할 수 있도록 하였다. 넷째, Vendor 데이터를 참고하여 상부구조의 핵심장비인 분리시스템에 대한 설계검증 Check list를 만들어 프로세스 엔지니어가 쉽게 사용할 수 있도록 하였다. 또한, 제안된 설계검증 모델의 확대 적용을 도모하고자 압축기(Compressor)와 열교환기(Heat exchanger/Cooler)에도 검증항목을 만들어 장비별로 설계검증이 이루어질 수 있도록 하였다. 이처럼 본 연구에서 제안한 방법(OC-Model : Operating Condition을 고려한 모델)을 적용할 경우 신속하고 체계적인 설계검증이 이루어질 수 있을 것으로 판단한다. 기대효과로는 제안된 설계검증 방법을 활용하여 상세설계의 효과적인 실행뿐만 아니라 초기 설계단계에서 기술적 에러나 불일치 사항 그리고 기술적으로 불충분한 사항을 미리 찾아냄으로써 해양구조물의 엔지니어링, 조달 및 건조에 대한 경쟁력을 향상시키는 데 기여 할 것으로 예상한다. 결과적으로, 제안된 설계검증 방법이 해양구조물의 FEED 검증 프로세스에 쉽게 적용될 수 있어, 향후 해양구조물 프로젝트의 성공적인 수행에 의한 이익창출을 도모할 수 있을 것이다. 또한, 해양구조물 건조 시 설계변경에 의한 막대한 손실을 최소화 할 수 있을 것으로 기대한다. 앞으로 이 방법을 FPSO 상부구조의 핵심장비인 압축기(Compressor)와 열교환기(Heat exchanger) 뿐 만 아니라 펌프(Pump)와 유틸리티 장비에도 확대 적용하여 그 효용성을 증가시킬 예정이다.

이동물체 실시간 탐지계측을 위한 LiDAR센서 및 알고리즘 구현

정종택 목포해양대학교대학원 2021 국내박사

In recent years, with the advent of Industry 4.0 era, research has been conducting in earnest on autonomous driving and unmanned technology. Technology that allows for object recognition of the surrounding environment is a vital facet of the system. Currently, a diverse set of sensors are utilized by the system for object recognition, such as: cameras, ultrasonic sensors, RADAR, and LiDAR(Light Detection and Ranging). At the same time, sensor technology is diverse and functionality is progressing rapidly in order to improve the capabilities of recognition technology. Amongst the previously listed sensors, LiDAR sensors utilizes pulse laser beams to produce highly precise distance measurements at a high resolution. Due to this feature, the LiDAR sensor is at a great advantage in its ability to identify small objects. LiDAR sensors are applicable to many fields due to the varying wavelength of its laser, from autonomous vehicles, military robotics, meteorology, to marine and terrain survey and mapping. However, in many recent studies utilizing LiDAR sensors, most were used with a wavelength of 1,550 nm, as it was found to be well suited for many circumstances, additionally the wavelength band is a visually safe wavelength that is safe for and invisible to the human eye. In particular regards to robotics and autonomous vehicle, precise sensors and object detection algorithms are required in order to improve the reliability of autonomous driving and unmanned technologies. Utilizing high-resolution LiDAR sensors is an obvious solution but the problem is that the cost is high. This study details the designing and implementation of a scanning-based LiDAR sensor for the industrial field where the utilization of the LiDAR sensor is increasing. Chapter 3 covers the development and design of segregating the errors and noise from raw data obtained from the sensors, the improvement of data continuity, the extraction of point clouds by trigonometric functions, and the detection and measurement algorithms based on a linear regression model. Chapter 4 covers data results obtained from practical experimentations, and how they verify and confirm designs of the LiDAR sensor, 3D viewer and the accuracy and feasibility of the linear regression model, and detection measurement and area detection algorithm. The result of the study can be reproduced in other LiDAR systems through confirmation and verification of the LiDAR sensor configuration and object detection algorithm.

필리핀 연안해운 안전정책 개선 연구

다이와 랜돌프 로이드 목포해양대학교대학원 2021 국내석사

Maritime Transportation is an important resource in a country like Philippines. Philippines a country which is composed of many small islands use ships as their main way of domestic trade. Small cargo ships to transport goods and services, passenger ships to carry tourists and locals, fishing boats and the like. In connection to this, there are accident and incidents that happened in the past that cannot be neglected, such as the asia’s titanic, wherein millions of lives were lost. Additionally there are collision, grounding, lack of AIS, and etc. Furthermore, the port facility infrastructures are in need of update, Aids to Navigation equipments are malfunctioning, lack of Vessel Traffic Management Systems to monitor vessel entry and exit, insufficient government support for the coastal shipping and shipbuilding, IT systems and data sharing are not yet fully utilized in government agencies, etc. Also, Philippines’Aids to Navigation (AtoN) facilities reported that only 72.73% of lighthouses and 68.22% of lighted buoys are operating. Moreover, some of the facilities that do operate are so old and deteriorated that their possible malfunction or failure may cause accidents at sea. The main objective of this paper is to a) improve the maritime safety, b) to prevent new accident and marine pollution casualties and c) to save lives and property. Likewise, it aims to present reasonable guide to improve its policy specifically on Coastal shipping. The maritime policy in the Philippines is administered by the three Safety Administration Bodies. Marina is involved in the maritime safety of the vessels plying in the Philippine waters, ship inspection, training and education of seafarers, issuance of certificate and shipyard regulation and etc. Philippine Coast Guard is tasked to make the country territorial waters safe and secure from any act or form of criminalities. It is tasked primarily with enforcing laws within Philippine waters, conducting maritime security operations, safeguarding life and property at sea, and protecting marine environment and resources; similar to coast guards around the world. Philippine Ports Authority is to provide reliable and responsive services in ports, sustain development of communities and the environment, and be a model corporate agency of the government. Establish a mutually beneficial, equitable, and fair relationship with partners and service providers. Provide meaningful and gainful employment while creating a nurturing environment that promotes continuous learning and improvement. Establish a world-class port operation that is globally competitive adding value to the country's image and reputation. In order to achieve this purpose, survey questionnaire were distributed and collected from different government agencies, shipping agencies and training center and seafarers and due to financial concerns, the researcher’s respondents are limited to 200 participants based on the National Capital Region of the Philippines. The researcher conducted cross tab and chi square analysis to determine the factors that affect the quality of coastal shipping in the country. To understand the result of the analysis, the researcher made a analysis model. In the analysis model there are five independent factor and five dependent factors. The five dependent variables for this study which have been measured through questionnaire surveys are law and institutional systems, government support, IT systems, navigation systems and infrastructures and the dependent factors are Maritime Industry Authority, Philippine Coast Guard, Philippine Ports Authority, Shipping Companies & Training Center and Seafarers. If the dependent factors were higher, the value of the independent factors would increase as well. These improvements will result in better performance of service, increased safety of passengers and also will lead to the improvement of safety in coastal shipping. As a result, the researcher found out that there are problems that exist such as the law & Institutional Systems are not made for government convenience, it is not made for demands convenience, the present seafarer education & training systems for IMO STCW are not in the satisfactory for trainees, ship's safety inspections are not being carried out in accordance with a proper way & manner, it is not easy for the user to obtain or purchase navigation equipments, it is not easy for navigators to obtain a useful navigation information, IT systems for vessel entry & departure procedures are not being utilized, IT basis procedures of data statistics are not well utilized, the government is not supporting enough ship financing subsidy for new building vessels, the vessels cannot be purchased freely from foreign countries without any government restrictions, the government is not supporting various welfare improvement policy for seafarers, port facilities for coastal shipping is not in the satisfactory conditions, sea traffic management systems are not in the satisfactory conditions, etc. Key words: Shipping policy, Safety Policy, Navigation, Coastal Shipping

소형선박의 친환경성능 평가를 위한 온실가스 배출량 시뮬레이션

정숙현 목포해양대학교대학원 2019 국내석사

Abstract Active researches and developments have been made in many industrial sectors as international efforts have become unavoidable for air pollution which has been accelerated by industrialization. Together with this, strong regulations have also been implemented for sustainable growth. In the maritime industry which accounts for majority of international logistics, regulation against air pollution for the ships over G/T 400-ton has been implemented by the IMO. MARPOL 73/78 Annex 6 which regulates the reduction of greenhouse gases emitted by ships especially contains EEDI (Energy Efficiency Design Index), EEOI (Energy Efficiency Indicator) and SEEMP (Ship Energy Efficiency Management Plan) which measure greenhouse gas emissions in technical and operational terms and indicate their effects. By managing the efficiency of logistics volume through these indexes, it has shown improvement in environmental effect through numerous studies on such various areas as engine development, optimization of ship shapes, substitution of biofuels and route optimization. In the case of vessels with less than G/T 400 tons which are excluded from the regulation, however, environment-friendly measures solely depend on the efforts of each country. Though they account for meager 13% of GHG emissions from marine transportation, their emission per ton exceeds that of container lines and tank lorry vehicles, which makes the problem urgent. To solve this problem, Korea has been developing electric propulsion for small ships, installing LED lights for attracting fish school and implementing fishery closure and the designation of low-speed operation in the port areas. However, these somewhat circumventive and indirect methods are considered unlikely to achieve effective results in any serious ways. In order to effectively measure the indicators which can practically judge environment-friendly effects of small ships, this study defines a method which measure the exhaust gas discharged from the engines even when the ships’ operating conditions are changed and examines its effectiveness through case studies. This study proposes a simulation method to measure greenhouse gas emissions to assess environmental impact applicable to small vessels in consideration of the fact that the main engines of the small ships are very diverse unlike the large merchant ships and loading statuses and speeds are varied. In addition, by comparing and analyzing its effects and differences, study also verifies the effectiveness of the proposed method which is an improvement of the method using LCA so far implemented as an assessment tool for environmental effect for small ships.

균형성과관리 개념 적용을 통한 국제해사규정 이행에 관한 평가모델 개발

최충정 목포해양대학교대학원 2021 국내석사

The International Maritime Organization (IMO) enacts and amends IMO instruments (including relevant regulations) on the safety of the sea and the prevention of marine pollution from ships, and strives for a safe and clean sea around the world. The failure to implement international agreements on maritime safety, security and protection of the marine environment introduced by the International Maritime Organization (IMO) increases the risk of marine accidents and the resulting maritime accidents have a negative human and physical impact on the shipping industry. Thus, the International Maritime Organization (IMO) continues to discuss globally to ensure the practical implementation of the IMO Convention and related regulations with the level of implementation of the same agreements. As it is required to improve the implementation level of the IMO instruments by evaluating the implementation level of the IMO Convention, an evaluation system such as Port State Control (PSC), the Self-Assessment of Flag State Performance, and the IMO Member States Audit Scheme have been introduced and implemented. First of all, the Port State Control (PSC), the Self-Assessment of Flag State Performance, and the IMO Member Audit System (IMSAS) are analyzed. The Port State Control (PSC) inspections evaluate the implementation of the IMO instruments of the flag ships, and the Self-Assessment of Flag State Performance requires the implementation of IMO instruments regarding the Flag States by using the self-inspection form. It was also confirmed that the IMO Member State Audit (IMSAS) is assessing the performance of the comprehensive competent administrations of the Flag State, Coastal Sate and Port State of entry into the instruments as a Contracting Government. Considering the need to more objectively evaluate the level of implementation of the IMO Instruments of Flag, Coastal, and Port States of the contracting parties to the IMO instruments, this study aims to present an evaluation model by developing Key Performance Indicators as a tool that can be used as an objective evaluation tool for the implementation performance of the IMO instruments based on the requirements of the IMO Member State Audit Scheme (IMSAS). In order to develop the evaluation model of the implementation of the IMO instruments, the strategic goal was to achieve the vision of IMO implementation plan in the Republic of Korea, "Securing the Best State Status to Implement the IMO Convention," and by analyzing the III Code based on the IMO Member States Audit Scheme, Critical Success Factors (CSFs) were derived. Based on the results, the III Code Evaluation Areas and Candidate Key Performance Indicators (KPIs) for the each III Code Evaluation Area were developed for the four perspectives (financial, customer, internal processes, learning and growth) of the implementation of the IMO instruments. In addition, a study model and surveys were designed for the development of the evaluation model. The study model was structured by tier 1 consisting of the III-BSC perspective, tier 2 consisting of the III Code evaluation area variables, and tier 3 composed of the evaluation indicator variables, which are the core evaluation indexes (KPIs), by layer. To analyze the validity of the candidate Key Performance Indicators (KPIs), a ranking scale survey using the SMART evaluation technique and a pair comparison survey were designed to analyze the weights of each tier of the research model. Based on the results of the surveys, the validity of the candidate's Key Performance Indicators (KPIs) according to the SMART evaluation technique was analyzed first and the final Key Performance Indicators (KPIs) were completed except for some of the candidate Key Assessment Indicators (KPIs) that were not feasible. The study model for the development of the evaluation model has been revised to reflect the revised Key Assessment Indicators (KPIs). The AHP (Analysis Hierarchy Process) was used to analyze the importance of each tier of the study model, and an IMO implementation evaluation model of the BSC perspective was presented based on the results. Key Performance Indicators (KPIs) developed in this study are presented, but no detailed formulas for the KPIs are specified for them. Also, there is a limitation of not sufficiently assessing the effectiveness of each entities' performance of the implementation. However, the evaluation method using the Key Performance Indicators (KPIs) from the BSC perspective on the implementation of the IMO instruments provides an opportunity for continuous improvement by identifying and measuring the performance of each indicator. Also, It is meaningful in that it provides organizations with a basic framework for communicating and achieving the vision and its strategies. In future studies, the efficiency of implementation of the instruments can be analyzed by maximizing the output result of input by each authority. Also, it will be possible to improve the implementation evaluation model of the IMO instruments by comparing and analyzing the strengths and weaknesses of the evaluation models developed by applying other various performance evaluation methods. I hopes that IMO Member States, including the Republic of Korea, will use the developed evaluation model of the Implementation of IMO instruments as a means to check or monitor the level of implementation of IMO instruments, thereby contributing to the improvement of the level of implementation of IMO instruments, and furthermore, the promotion of the implementation of the IMO instruments will contribute to maritime safety and protection of the marine environment.

평수구역을 운항하는 카페리선박의 차량고박 기준에 관한 연구

강병선 목포해양대학교대학원 2021 국내석사

The importance of cargo lashing has been raised after passenger ship sinking accidents due to failure of vehicle and cargo lashing and transshipment of cargo due to rolling. Accordingly, the code of equipment and structure of car ferries has been strengthened that all vehicles loaded on the car ferry that operate only in the smooth sea area, whose voyage time is less than 30 minutes and operate in the smooth or costal sea area, whose voyage time is less than 1 hour must be secured on the state of sea over 7m/s wind speed and/or over 1.5m wave height. Currently, the relevant contents have been changed to the code of cargo loading and securing, etc., on 2nd January 2015 and the systematic process for verifying the validity of securing is described according to the Annex 1, Standards for Cargo Stowage and Securing, Etc. Since this code accepted the contents of the IMO CSS(Code of Safe Practice for Cargo Stowage and Securing) and applies the external force acting on ocean sailing vessels, it is considered to be practically unreasonable to apply it to ships sailing in the domestic coastal sea area. This is because ships sailing in the coastal sea area exhibit relatively smaller hull motion than ships sailing in the ocean due to the geographical characteristics of the coastal sea area. Therefore, in this study, the hull motion of a ferry passenger ship that is not enclosed in a vehicle area sailing in the coastal sea area was measured and after comparing and analyzing the result of the hull motion calculation program(NSM), the external force according to rolling & pitching was applied to the vehicle loaded on the ship. Examining the lashing standards for car ferry ships sailing in the coastal sea area by comparing the external force with the bearing capacity that the vehicle can withstand without securing, it was found that loaded vehicles did not slip or tip over on the state of sea over 7m/s wind speed, 1.5m wave height and also, it is considered that the current lashing standards could relax after further study.

Logistic Regression을 이용한 선박 충돌 위험 정보 Classification Model 개발에 관한 연구

양영훈 목포해양대학교대학원 2021 국내박사

In the accident of a collision, the distance at which the other ship was first detection range was either not found or less than 1 mile, and it was investigated that the ship operator did not recognize the ship's approach until the impending collision. As in the case of statistics, considering the situation in which the target ship is recognized from a very close distance in a collision accident, in order to prevent accidents, it is essential to secure sufficient first detection range and initial action in advance. In this study, The Risk Informed Classification Model (RICM) was developed that can recognize the encounter situation of the target ship from a sufficient distance in order to secure a first detection range to prevent collision between ships. For this study, a COLREG-based Encounter Classification Model (ECM) was applied to determine the ship's encounter situation, and based on the survey results in which experienced ship’s officer, using the Logistic Regression(one of the machine learning methods), developed a model that provides information and warning notifications to ship operators so that they can secure a first detection range from the risk of collision with other ships. Using Logistic Regression, developed a model 1 that judges whether collision risk information needs to be provided in advance for overtaking, crossing, head-on, and ambiguous encounter situations, and a model 2 that determines and provides information and warnings. As a result of verifying and analyzing the RICM model, it was analyzed that all of the dependent variables were statistically significant in the length and speed of the own and target ships, DCPA, Range, and TCPA used as independent variables. In general, the larger the size of the ship, the higher the ship speed, and the closer the distance to target ships, the more subjective risk the ship operator feels tends to increase, and it was confirmed that the RICM model similarly follows. The satisfaction of the captains who are currently receiving the RICM model collision risk information service in real time through the e-Navigation monitor was evaluated, and it was found that they were generally satisfied with the provision of collision risk information. In addition, it was suggested that it is useful in a situation of low visibility. As a result of comparing and analyzing maritime traffic data for ships receiving collision risk information by RICM model in real time and ships using general AIS, it was analyzed that there was no distinct difference. If information and warning notifications by the RICM model were received, it was expected that the passing distance with the other ship would increase, but the difference could not be confirmed. It was confirmed as a limitation that long-term observation and data acquisition are required to evaluate the traffic effect. This study is expected to serve as a basis for research on providing information to prevent future ship collision accidents. Continuous RICM model effect analysis, traffic evaluation, acquisition of additional learning data, and model advancement will contribute to the prevention of ship collision accidents.

유중 가스 분석을 이용한 전력용 변압기 상태진단의 시각화 판별법

김용현 목포해양대학교대학원 2021 국내박사

고도 성장기에 설치된 대량의 전력용 변압기가 수명에 근접함에 따라 상태와 수명을 평가할 수 있는 진단기술의 필요성이 대두되고 있다. 유중 가스 분석법은 변압기의 상태 진단에 효과적인 방법으로 인정받아, 국내에서는 1983년부터 전력용 대용량 변압기의 정기적인 상태 진단법으로 이용되고 있다. 유중 가스를 분석하여 상태를 진단하는 대표적인 방법으로는 주도형 가스 방법, 가스간 비율 방법 및 시각화 판별법이 있다. 특히 시각화 판별법은 결함의 상태를 시각적으로 파악하기 편리하고 진전 상태를 확인할 수 있어 현재 가장 널리 사용되는 기법이다. 그러나 지금까지의 시각화 판별법은 변압기의 이상 여부 판단만이 가능하였고, 결함 유형의 판단은 적절하지 못하였다. 기존 판별법의 오류를 개선하기 위해 가스의 종류와 농도에 따라 위험도를 반영할 수 있는 정규화 방법을 적용하였고, 가스 패턴과 결함 위치로 결함유형을 재정립하여 조치방안을 제시하였다. 또한, H2, C2H2, C2H4 및 C2H6 가스를 이용한 사각 판별법을 제안하였다. 제안된 새로운 사각 판별법은 변압기의 경제적인 유지보수 전략 의사결정을 위한 상태평가 정확도 향상에 많은 기여를 할 것으로 판단된다.

내항선박 안전성 평가시스템 구축에 관한 연구

채병근 목포해양대학교대학원 2021 국내석사

Coastal ships related accidents occupy a large proportion of total marine accidents. For the past years, a number of studies on maritime safety policies and safety management evaluation standards of shipping companies have been conducted, but no study has been conducted to develop a system that can assess the safety of coastal ships. Since 2015, the government has been maintaining supervision and guidance for coastal ships and shipping companies through the maritime safety supervisor system to discern whether maritime accidents may occur or whether maritime safety management is properly implemented. However, because the number of coastal vessels greatly outnumbers the maritime safety supervisors that it would require a significant amount of time to inspect all subjected vessels. This study aims to establish a safety assessment system suitable for the coastal ships which reflect their actual circumstances to identify non-standard ships that may cause marine accidents. To this end, after analyzing the ship risk profile used in the port state control system, the opinions of the expert group were collected, and eight evaluation elements and detailed items for each evaluation element were selected, and a questionnaire survey by the expert group was conducted. The survey results were analyzed by the Analytic Hierarchical Process method to calculate the weight of the evaluation elements, and the weight of the detailed items of evaluation element was calculated through the frequency analysis. After that, the ‘Safety assessment matrix’ was established to assess the safety of coastal passenger ships and cargo ships from an objective point of view by collecting opinions of expert groups. This study is believed to contribute on the prevention of marine accidents by identifying intensively managed ships based on this study to improve the efficiency of inspection manpower and the objectivity of inspection for coastal ships

공장 환경에 대한 건물인입손실 모델 개발

카이룬니사 빈티 아지딩 목포해양대학교대학원 2021 국내석사

In this study, a model for a heavy industrial factory in an International Telecommunication Union-Radiocommunication (ITU-R) building entry loss (BEL) model is developed. In addition, a new parameter of a reflected power (RP) is proposed and modeled for prediction of an outdoor-to-indoor (O2I) path loss on non-line-of-sight (nLoS) environments. To examine the BEL model on a factory environment, BEL measurements were carried out at frequency range of 3 to 24 GHz. The BEL characteristics are analyzed and the parameters of the model are extracted from the measurement results. As the result of analysis, it reveals that the BEL model for the heavy industrial factory is significantly different from that of the traditional building in the ITU-R BEL model. A new classification of the building may be required for the industrial applications. Additionally, in order to investigate the impacts of the external environment on the BEL and whole propagation loss, a measurement campaign is proposed according to the presence and absence of the main clutter (a big training ship) behind the targeted building. The BEL measurements were performed and analyzed on the nLoS path and being compared with the line-of-sight (LoS) path from 3 to 24 GHz. The proposed parameter, RP, is developed and extracted by using the measurement results. The results confirmed that the error is significantly decreased when the RP parameter is added rather predicting the excess loss (EL) only by the sum of BEL and clutter loss (CL). The prediction model is proposed for the O2I path loss on the nLoS environment.