• 해양환경안전학회지
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• 제22권1호
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• pp.1-10
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• 2016

본 연구에서는 함평만의 육상기인오염 물질의 유입특성을 파악하고, 물질순환을 정량화하기 위해, Simple box model을 적용하였다. 함평만의 하천 유입 오염부하 특성을 보면, BOD, COD, TOC의 평균 유기물질 오염부하가 각각 79.7 kg-BOD/day, 144.06 kg-COD/day, 93.0 kg-TOC/day를 나타내었다. 하천별 유기물 유입 오염부하량은 손불 방조제>주포교>양만단지 순으로 나타났다. 계절별로는 하계 강우시기인 7월에 높은 부하 특성을 보였다. 영양염류의 평균 유입 오염부하는 각각 20.9 kg-DIN/day, 17.1 kg-DIP/day, 148 kg-TN/day, 37.4 kg-TP/day를 나타내었다. 하천별 영양염 유입부하량은 양만단지>백옥교>주포교 순으로 나타났다. 박스모델을 이용한 함평만 물질수지에서 담수체류시간은 52.4일로 해수교환이 낮은 반 폐쇄성 해역의 특성을 나타내었다. 영양염 물질수지에서 용존 무기질소의 경우 ${\Delta}DIN$이 (-)의 탈질상태를 나타내어 유입된 질소보다 광합성에 의한 소비 및 외해 유출이 큰 경향을 보였다. 용존 무기인의 경우 ${\Delta}DIP$가 (+)를 나타내어 유기물 분해에 의한 공급, 퇴적물의 용출부하, 하천 유입부하가 식물플랑크톤에 의한 소비 및 외해 유출보다 큰 것으로 나타나 축적되는 경향을 보였다.

• 해양환경안전학회지
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• 제6권1호
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• pp.11-22
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• 2000

The paper describes creation methods of background scenes to implement realistic virtual environments in the VRSS (Virtual Reality Ship Simulator). VRSS is next-generation system constructed with virtual tools in a virtual space. Thus, it could have many benefits compared to conventional ship simulators composed with heavy bridge mock-up system and wide visual presentations. In this work, we developed effective 3D object modeling techniques, and constructed virtual harbor scene by using 3D-Webmaster authoring tool. The virtual harbor was built with object-oriented 3D objects modeled to interact with user's action. With the immersion-type VR system, we created virtual harbor environments in a virtual space, and discussed on the naturalness of the scene with test results of SDMPA (Semantic Differential Method for Psychophysical Assessment) by 10 subjects. As the results of subject assessment, all of the participants could felt natural-like harbor. Therefore, we found that the proposed creation methods and procedures of background scene are enabling to fit to the full mission VRSS construction.

• Journal of Advanced Marine Engineering and Technology
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• 제27권6호
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• pp.783-789
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• 2003

An experimental method to investigate the fracture strength and fracture toughness for the silicon nitrides sintered at various sintering temperature is established. The erosion rate for these materials in the various concentration of NaOH solution is also investigated. In result, the fracture strength of Si3N4 is decreased with the increase of sintering temperature. On the other hand, the fracture toughness KIC is increased with the increase of sintering temperature. The erosion rate of silicon nitride in the NaOH solution depend largely on the grain size and the concentration of NaOH solution. The erosion rate of silicon nitride sintered at $1800^{\circ}C$ was much higher than that at $1950^{\circ}C$. These results are due to the unique columnar structure of silicon nitride.

• 한국항해항만학회지
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• 제27권6호
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• pp.611-618
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• 2003

It can be said that the relationship between the maneuvering ability of operators and the navigational environment affects the safe degree of navigation in the collision avoidance situation. In order to reduce the occurrence probability of accident and to maintain the safety, it is necessary to clarify the relationship between human behavior and navigational environment. In this study, therefore, we analyzed and discussed the relationship between the maneuvering characteristics and the safety focused on human behavior as a fundamental factor of marine accidents using ship handling simulator and questionnaire. As a result, we concluded that navigational environment changes variously and the maneuvering ability of operators also varies with the navigational environment, and the ship handling characteristics strongly affect the occurrence probability of accident.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계 학술발표회 논문집(II)
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• pp.241-244
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• 2006

The basic prediction model was constructed to obtain optimal maintenance method for concrete structure under marine environment by exploring the mechanism of mono and combined deterioration in lab. This model was planned to be upgraded with data acquired from several exposure specimens under same environment as structures. The computer program developed to give useful guidance observer would be improved. Several repair materials and repair construction methods applied to exposure specimens will be tested for its performance of prohibit salt attack and freezing & thawing action during experimental period about ten years. All of these data could be available to complete the prediction system. The manager will be able to use the system for optimal maintenance of marine concrete structures.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2005년도 후기학술대회논문집
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• pp.200-201
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• 2005

This paper is analyzed a new modulation method of OSW(Optimized Sine-Wave) modulation strategy for cascaded H-bridge multi-level inverter. The inverter structure was modified with the maximum output voltage level, and the switching angle was calculated easily to adjust the requested Vrms of the output. The suggested modulation method could make output waveform very close to the ideal sine wave, and the THD value was improved also remarkably.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2005년도 후기학술대회논문집
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• pp.11-12
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• 2005

BMS & Governor System은 선박용 추진 기관으로 사용되는 저속 디젤 엔진의 원격 운전 및 제어를 담당하는 시스템으로 선박 추진과 엔진 제어에 필수적인 중요 구성 요소이며, 조선 기자재관련 고부가가치 산업의 한 부분이다. 그러나 조선관련 산업에 있어서 세계 최강국의 위상에 걸맞지 않게 국내에는 BMS & Governor System의 독자 모델이 없는 실정이고, 유럽이나 일본의 제품으로 전량 수입에 의존하고 있는 상황이다. 이에 선박 추진용 저속 디젤 엔진을 위한 제어 시스템의 관련 기술을 연구하여, SEA-CAPS를 개발하였다. 본 연구에서는 BMS & Governor System에 대한 개요와 SEA-CAPS의 개발 내용, 그리고 환경 및 성능 시험에 관한 내용을 언급하고자 한다.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2006년도 전기학술대회논문집
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• pp.253-254
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• 2006

this paper suggest a new space vector PWM modulation method with short processing time which does not need idenfication of nearest three vectors(NTV) and duty calculation for each vector. The suggested PWM method makes mean value of phase voltage to be same as reference during every modulation period by use of a triangle in small hexagon on multi-level vector space. This paper described the suggested modulation method can be successfully applied to the space vector modulation use of multi-level inverter by computer simulations and experiments.

• Journal of Advanced Marine Engineering and Technology
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• 제22권6호
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• pp.894-900
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• 1998

In this paper, a communication method is proposed for the development of a main engine remote control system. The main engine control system compriese three subsystems such as RCS (Remote Control System) BCS (Bridge Control System) and SS (Safety System), Thus it is required to exchange data each other among these subsystems. The communication method has simplified hardware through the minimization of communication components where the interrupt method are employed for receiving and the polling method for transmitting. We discuss a methodology of using a ring buffer for data storage physically which has two buffers virtually for the effective use of memory. This communication method presents a good performance in the system which has rather small numbers of communication data.

• 수산해양교육연구
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• 제29권2호
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• pp.544-551
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• 2017

Metaheuristic algorithms are efficient techniques for a class of mathematical optimization problems without having to deeply adapt to the inherent nature of each problem. They are very useful for structural design optimization in which the cost of gradient computation can be very expensive. Among them, the characteristics of simulated annealing and genetic algorithms are briefly discussed. In Metropolis genetic algorithm, favorable features of Metropolis criterion in simulated annealing are incorporated in the reproduction operations of simple genetic algorithm. Numerical examples of structural design optimization are presented. The example structures are truss, breakwater and steel box girder bridge. From the theoretical evaluation and numerical experience, performance and applicability of metaheuristic algorithms for structural design optimization are discussed.