• Nuclear Engineering and Technology
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• 제21권4호
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• pp.308-320
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• 1989

이 연구는 PWR를 모의한 2루프장치에서 1차냉각재의 재고량 및 비응축성가스가 단상 및 이상 자연순환에 미치는 영향을 실험적으로 조사하고져 한 것이다. 실험장치는 U튜브를 가진 2개의 열교환기로 구성되었다. 일련의 실험을 통하여 다음 사실을 확인하였다. 이상 자연순환의 유량은 1차 냉각재 재고량의 크기에 크게 의존한다. 본 실험에서는 이상 자연순환을 유지하기 위해서는 1차 냉각재 재고량의 수위가 노즐 중심선을 유지해야 함을 알게 되었다. 비응축성 가스의 존재는 단상 자연순환을 정지시킬 수 있으며 그러나 이상 자연순환에는 큰 영향을 주지 않는다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.643-648
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• 2005

Generally, ships have marks of various shapes on outside of the hull. Among them, so called "Draft Mark" indicates the distance from the bottom of the keel to the waterline. Draft marks are used to determine the displacement and other properties of the ship for stability and control purposes. These marks are made up of welding bead or sticking the steel plate on outside of the hull. To improve the confidence level of the ship owner, quality and accuracy of the draft mark is very important. So the automatic mark welding robot is used to enable a high quality and accurate manufacturing line. To improve the system portability, the system is divided into two distinct parts, namely mechanical part and control part. Mechanical part is robust, a lightweight, and easy to dismantle. The control part consists of an in-house developed controller, which is based on embedded Linux. Also, the control part consists of power line communication module to ensure the applicability of the controller in manufacturing line. In this paper, the methodologies of control and configuration of the robot are discussed.

• Ocean and Polar Research
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• 제35권4호
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• pp.291-298
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• 2013

In order to investigate the topography and exposure duration of the Siheung tidal flat, tidal ranges and DEM constructed by remote sensing techniques were analyzed. A cross-sectional diagram of the intertidal area reveals that it is relatively flat in the upper zone and then abruptly plunges into the bottom of the main channel where elevations increase in an upstream direction. The waterline during the Highest Low Water (HLW) is drawn back to the bottom of the channel at the middle part of the tidal flat and is formed along the slant of the channel during the Lowest High Water (LHW). The intertidal zone is located between -410 cm and 510 cm in terms of elevation and its total area is $0.65km^2$. An area between the Highest High Water (HHW) and Lowest High Water (LHW), occupying about 80% of the total area, occupies $0.52km^2$ of total area and accounts for 56% of the exposure duration. The boundary of wetland protection area in the Siheung tidal flat did not exactly coincide with the intertidal regime and differs by more than 15%. This study, which precisely analyzed the tidal flat area, tidal environment, and topography, would be useful in making a conservation plan and in learning how to use a wetland protection area in a sustainable manner.

• 대한조선학회논문집
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• 제32권3호
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• pp.19-28
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• 1995

본 논문은 국내 최초로 개발된 300톤급 반잠수쌍동선형 해상시험선의 선형설계 및 성능분석 결과에 대하여 기술한다. 선형의 수면하부 형상을 정의할 수 있는 11가지 형상인자를 도입함으로써 체계적인 형상변경이 가능토록 하였으며, 이를 통해 복수개의 선형을 도출한 후 설계목표 및 설계 제한조건과 부합되는 최종 선형을 선택하였다. 설계선형의 제반 성능을 이론 및 수조모형시험을 통해 상세히 검증하였으며 실선시험에 의해 목표 성능이 발휘됨을 입증하였다.

• 동력기계공학회지
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• 제17권2호
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• pp.95-102
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• 2013

For vessels operating in the cold climate regions, the ballast water inside or hopper tanks above the waterline may be frozen, starting at the top of the tank and at the side walls. Therefore, countermeasures against freeze-up of the ballast tank such as air-bubbling system, hot steam injecting system, heating coil system and water circulating system are taken to prevent freeze-up phenomenon; however, there are no rigorous investigations of anti-freezing to examine the effectiveness and validity of systems against freeze-up of the ballast tank, in which the temperatures are about $-25^{\circ}C$ (ambient air temperature) and $0^{\circ}C$ (sea water), respectively. In this paper, to ensure reasonable specifications for cold regions if the measures from the above-mentioned systems against freeze-up are effective, the phenomenon of ballast tank freeze-up is simulated and discussed in low temperature conditions. With the results using the commercial CFD code, CFX 14, the most cost-effective solution is conducted to prevent being frozen along the outer surface.

• 한국해안해양공학회지
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• 제12권1호
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• pp.19-26
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• 2000

폭풍발생에 따른 해안종단방향의 표시이동은 경빈과 사구의 침식, 연안사주의 생성등 해안단면변화에 있어 주요한 요인의 하나로 알려져 있다. 그러나 폭풍발생에 따른 표사이동은 표사의 입경, 수면상승높이, 쇄파고 등 많은 요소들에 의해 복합적으로 작용하기 때문에 현재에도 정확한 예측이 어려운 실정이다. 본 논문에서는 해안단면에서의 평형에너지소산개념과 표사량 예측에 있어 주요한 요소인 표사량 파라미터를 차원해석을 통하여 변수화하고 수치모델에 도입하여 폭풍발생에 따른 해안종단방향의 해안단면변화와 해빈침식에 대하여 분석하여 보았다. 해안종단방향의 해빈침식은 단면형상 파라미터, 표사량 파라미터, 수면상승높이에 의해 크게 영향을 받음을 알 수 있다.

• 동력기계공학회지
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• 제17권5호
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• pp.30-37
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• 2013

For vessels operating in the cold climate regions, the ballast water inside or hopper tanks above the waterline may be frozen, starting at the top of the tank and at the side walls. Therefore, countermeasures against freeze-up of the ballast tank such as air-bubbling system, hot steam injecting system, heating coil system and water circulating system are taken to prevent freeze-up phenomenon; however, there are no rigorous investigations of anti-freezing to examine the effectiveness and validity of systems against freeze-up of the ballast tank, in which the temperatures are about -$25^{\circ}C$ (ambient air temperature) and $0^{\circ}C$ (sea water), respectively. In this paper, to ensure reasonable specifications for cold regions if the measures from the above-mentioned systems against freeze-up are effective, the phenomenon of ballast tank freeze-up is simulated and discussed in low temperature conditions. With the results using the commercial CFD code, CFX 14, the most cost-effective solution is conducted to prevent being frozen along the outer surface.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2001년도 춘계학술대회 논문집
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• pp.186-195
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• 2001

The purpose of this study is to develop the time-dependent, one-dimensional numerical model on the interaction between irregular waves and two-layer permeable coastal structures, by extending and modifying the numerical model PBREAK(Wurjanto and Kobayashi, 1992) which is applicable only to one-layer permeable coastal structures. The two-layer permeable coastal structure consists of two permeable underlayers with different permeable media resting on an impermeable slope and an armor layer covering the permeable underlayer. The numerical model of this study simulates the wave over rough permeable underlayer of arbitrary geometry as well as the waves inside two-permeable underlayers of arbitrary thickness for specified normally-incident irregular waves. The utility of the numerical model is founded from comparing with PBREAK and the four hydraulic model tests under irregular waves. The sensitivities of computed results according to typical parameters(porosity, stone diameter, horizontal width of the permeable underlayer) and major factors(friction factor of primary armor layer etc.) discussed.

• 한국해양공학회지
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• 제26권6호
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• pp.74-79
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• 2012

The present study aims at suggesting the systematic approach to analyze the local drag components as the resistance performance characterized by the flow of the ship. In order to identify the local areas, the hull surface is decomposed into SVM (Station-Vertical Section Map) which consists of 20 stations along the longitudinal direction and 20 sections along the vertical direction (from the bottom to the waterline). Successively, on the SVM, the friction and pressure drag coefficients as the components of total drag coefficient have been analyzed for two different hull forms of Wigley and KVLCC by using CFD.

• 대한조선학회논문집
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• 제45권3호
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• pp.258-268
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• 2008

The radiation potential of a ship advancing in waves is studied using the 3D time-domain forward-speed free-surface Green function and the Green integral equation. Numerical solutions are obtained by making use of the 2nd order BEM(Boundary Element Method) which make it possible to take account of the line integral along the waterline in a rigorous manner. The 6 degree of freedom motion memory functions of a hemisphere and the Wigley seakeeping model obtained by direct integration of the time-domain 3D potentials over the wetted surface are presented for various Froude numbers.