김화영 교수

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Green vehicles include electric vehicles, natural gas vehicles, fuel cell vehicles (FCV), and vehicles running on fuel such as a biodiesel or an ethanol blend. An FCV is equipped with a cylinder valve installed in an ultra-high pressure vessel to control the hydrogen flow. For this purpose, an optimum design of the solenoid actuator is necessary to ensure reliability when driving an FCV. In this study, an electromagnetic field analysis for ensuring reliable operation of the solenoid actuator was

A pilot-operated solenoid valve is used to control ultra-high pressure vessels. However, it is difficult to understand its dynamic behavior because the valve operates under ultra-high pressure conditions and the driving unit moves in a multi-step fashion in a tight hidden space. This study aims to identify the system coefficient, especially the damping coefficient, required to analyze the dynamic behavior of a solenoid driving unit. Experiments to measure the dynamic behavior of the driving unit

The Republic of Korea (ROK, South Korea) boasts a 5,000-year history. However, it is better known for recovering from the complete destruction caused by the Korean War (1950-1953) and for accomplishing ‘the Miracle of Han River’. In 2010, South Korea joined an OECD member nation to provide aid. In doing so, it became the only country that used to receive assistance from other countries to now provide aid to other countries. Since the Korean War, South Korea has constructed various social infrast

This paper presents a new multiobjective approach to solve sedimentation problems behind weirs and low-head dams. The multicriteria decision analysis (MCDA) framework is used to improve reservoir operation rules for Sangju Weir in South Korea. A series of stage and discharge constraints can be developed to include consideration for reservoir sedimentation, hydropower generation, flood control, water supply, irrigation and drainage, and environment. Seasonally changing operation rules can help mi

This study analyzed what factors most affected the changes in South Korean industries' energy oil consumption rate and determined the most applicable decomposition methodology. LMDI I, LMDI II, AMDI, Laspeyres, Paasche, Fisher, and Marshall-Edgeworth analysis methods were tested for the study. Multiplicative method, based on the energy intensity approach, was also tested. The results between the different analytic methods showed only minor differences and these differences did not have any signi

The construction of eight consecutive weirs along the Nakdong River changed the erosion and sedimentation patterns after the Four Major River Restoration Project. This study examines the sedimentation problems upstream of Sangju Weir with a new procedure combining: (1) the flow-duration; (2) the sediment rating curve; (3) the series expansion of the modified Einstein point procedure; and (4) the trap efficiency. For weirs or low-head dams, trap efficiency is not only a function of sediment size

Growing concerns regarding air pollution have recently increased the demand for liquefied natural gas (LNG) fueled ships. LNG-fueled ships are equipped with an explosion relief valve in the crankcase to relieve excessive pressure and stop flames from emitting from the crankcase. In this study, a finite element analysis was conducted to evaluate the crankcase relief valve disk spring design using an ANSYS Workbench, v.15. The setting pressure, leak and explosion test performed by european standar

우리나라는 세계 5위의 자동차 생산국이고 전체 제조업 가운데 자동차 산업이 차지하는 비중이 높다. 그리고 우리나라 10대 수출품목 중 2위를 차지할 만큼 중요한 산업이다. 우리나라는 국내외에서 생산된 자동차 중 약 300만대를 수출하고 있다. 우리나라와 함께 일본도 자동차 산업 비중이 높고 전 세계에 약 400만대 이상의 자동차를 수출하고 있다. 우리나라와 일본 모두 국내에서 생산된 완성차와 중고차를 선박을 통해 수출하고 있다. 따라서 자동차 생산공장 인근에 자동차 부두가 개발되어 이용되고 있다. 그러나 자동차 수출항만에 있어서 열악한 부두시설, 수출입 자동차 선적 또는 하역을 위한 야드 공간의 부족, 자동차 하역에 비전문화 된 하역업체의 숙련도 부족 등으로 하역이 지연되거나 자동차전용선이 대기하는 등의 비효성의 문제가 발생하고 있다. 따라서 본 연구에서는 우리나라와 일본의 자동차 수출항만의 효율성을 측정하여 비교·분석하는데 목적이 있다. 자동차 수출항만의 효율성 측정을 위하여 자료

This paper aims to find out future tasks of GICOMS(General Information Center on Maritime Safety & Security) through identification of required system for implementation of e-Navigation. We derive nine advancement subjects for model of advanced GICOMS through brainstorming with experts of maritime safety. And then, we analyze the structure of extracted nine advancement subjects using by fuzzy structural modeling method, and propose a structural model that grasps the correlation between eleme

Controlling pull-wire tensions and overhang lengths based on simulation results substantially improves the target accessibility of the catheter tip.

이 연구의 목적은 해양대학교 교과과정 중 6개월 간 실습선 승선실습 교육에 대한 만족도를 조사하는데 있다. 승선실습 교육은 1년간 이루어지며 졸업 후 초임해기사로 근무하는데 있어서 필요한 실무를 직·간접적으로 교육하는 것으로 해기면허 취득 및 선박 안전운항을 위한 실무를 익히는데 있어서 매우 중요한 교육과정이다. 특별히 본 연구의 대상이 되는 목포해양대학교 실습생은 1년의 승선실습 기간 중 6개월은 학교실습선에서 나머지 6개월은 해운업체에서 위탁실습을 하게 된다. 이 논문에서는 실습선 승선실습교육 만족도 조사를 위하여 승선실습 운영, 교육내용, 지도교수 및 조교, 시설 및 환경, 교육효과로 구성된 5개의 요인과 요인별 총 27개 문항의 설문항목을 설계하고 가설을 세워 통계적 분석방법을 이용하여 검증하였다. 또한 교육만족도에 영향을 미치는 요인을 분석하고 실습생들의 교육만족도가 졸업 후 해운회사 취업 등 진로의식에 어떤 영향을 미치는지 분석하였다.This paper aims to id

Social media platforms play a central role in the structure of political discourse today. It is imperative to theorise about why and how we should regulate these institutions to manage some of the problems they raise for political discourse, namely misinformation and disinformation, hate speech, and polarising content. In this paper, I scrutinise their business models to form a basis of justification and strategy to regulate social media platforms. I argue that, in virtue of their business model