• 한국항해항만학회지
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• 제29권8호
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• pp.661-666
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• 2005

최근 거대 지진에 의한 쓰나미 발생 확률이 대단히 높다고 경고하고 있다 특히, 항만내의 선박 운용이라는 관점에서, 쓰나미에 의한 막대한 재산 및 인명 피해가 염려되기 때문에 쓰나미에 의한 계류 선박의 영향을 고려하는 것은 대단히 중요한 일이다. 쓰나미가 발생하면 항만 부근에서 입출항중의 선박은 표류를 시작하게 되며, 계류중인 선박도 계류색이 절단되어 표류에 이를 가능성이 높다. 또한, 좌초 및 안벽 충돌 등에 의한 엄청난 사고가 발생할 가능성이 존재한파. 한편, 쓰나미는 수분 정도의 성분파를 포함하고 있기 때문에 계류 선박의 장주기 운동과 공진할 가능성이 높으며, 쓰나미의 유속은 항내에서 발생하는 조류에 비해 대단히 크기 때문에 른 항력이 선박에 작용할 가능성이 있다. 본 연구에서는 대규모 쓰나미의 내습으로 인한 선박 운동의 관점에서 수치 시뮬레이션 과정을 검토하고, 선박 운동에의 영향 및 계류 하중을 수치실험으로 평가한다.

• 한국염색가공학회지
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• 제22권4호
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• pp.373-379
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• 2010

The laboratory inspection and analysis of several types of ropes such as edge tensile test, D/d tensile test and abrasion test were carried out in order to investigate the abrasion degradation by external damage and to obtain the fundamental data for measurement against the abrasion. PET ropes were socketed and evaluated under tensile testing. A yarn-on-yarn abrasion test machine has been developed to study the damage and failure associated with rubbing between fiber surfaces. The abrasion test method consists of sliding a length of interwrapped yarn against itself in a reciprocating fashion, either dry or immersed in liquid. It has also been adapted to measure yarn-on-yarn friction. The influence of spin finish on yarn friction and abrasion was investigated extensively. This study indicates that finish has a major effect not only on yarn performance but also on rope performance under the marine environment.

• 수산해양기술연구
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• 제52권4호
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• pp.290-298
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• 2016

This study aims to reduce the force exerted to the buoy of the gillnet by wave and current. Five buoy models were selected for experiments and their rope tensions under wave and current action were compared. Five models were EL (ellipsoid), EL-H (ellipsoid-hole), SL (streamlined body), SP (sphere) and CL (cylinder, traditional type). In the first experiment, the Five models were tested without any attachment. In the second experiment, a flagpole was attached to each model. As a result, in the condition without flagpole, the tensions of four models with the exception of the CL were about a half of that of the CL. In the condition with flagpole, the tension of all models was twice larger than that without flagpole. Thus, a new model was suggested to improve the problem, which has a combined body that of a flagpole and a buoy Three new models of CL-L (long and thin cylinder), LF (leaf shape) and LF-F (leaf shape with fin) were designed. Also a cylinder type (CLD) with a flagpole as a control was included in the experiment. As a result, the LF-F had the smallest tension and a half tension of the CLD. Therefore, it is supposed that the flagpole and buoy combined model could reduce the tension on buoy rope and contribute to improve the gillnet loss problem.

• 전기학회논문지
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• 제66권10호
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• pp.1532-1539
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• 2017

The floating photovoltaic system is a new concept in the renewable energy technology. That is similar to land based photovoltaic technology except floating system. So the system needs buoyant objects, mooring, ect, besides modules and supports, and that is able to withstand in water level changes and wind strength. Therefore the floating photovoltaic system is much different from land photovoltaic system. K-water (Korea Water Resources Corporation) has been operating two floating photovoltaic system that's capacity is 100 kW and 500 kW respectively since in summer 2011 for commercial generation, and have construction project for 2,000 kW in Boryeong multipurpose Dam and other areas. Furthermore K-water was developing a tracking-type floating photovoltaic system at Daecheong multipurpose Dam and developed and installed an ocean floating photovoltaic demonstration plant at Sihwa Lake in October 2013 for R&D. In this paper, we introduce that structure of floating photovoltaic system include buoyant structure, mooring system and auxiliary device. Especially the rope which is in part of mooring should be always maintain tension under any water level. Also we explain about structure design concept to wind load in an every loading condition and a kind of structure materials and PV structure types used in water environment. Especially ocean floating PV system is affected by tidal current and typhoon. So there are considering the elements in design. Finally we compare with floating and land photovoltaic on power amount. As a result of that we verified the floating photovoltaic system is more about 6.6~14.2 % efficiency than a general land photovoltaic system.

• 한국CDE학회논문집
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• 제15권1호
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• pp.70-83
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• 2010

Recently, floating cranes are mainly used to erect heavy blocks or cargos for constructing ships in many shipyards. It is important to estimate the dynamic motion of the heavy cargo suspended by a floating crane and the tension of the wire ropes between the floating crane and the heavy cargo. In this paper, the coupled dynamic equations of motion are set up for considering the 6 degree-of-freedom floating crane and the 6-degrees-of-freedom heavy cargo based on multibody system dynamics. Depending on the cargo weight, the motion of the floating crane would be changed to nonlinear state. The nonlinear terms in the equation of motion are considered. In addition, the nonlinear hydrostatic force, the linear hydrodynamic force, wire rope force, mooring force and gravity force are considered as the external forces. As the result of this paper, we analyze the engineering effect for erecting the heavy cargo by using the floating crane.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2010년도 정기 학술대회
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• pp.192-195
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• 2010

본 논문에서는 해상 크레인과 중량물의 동적 거동을 시뮬레이션하기 위해, 유한 요소 정식화(finite element formulation)를 이용하여 해상 크레인의 붐(boom)을 탄성체로 모델링 하였다. 붐은 3차원 탄성 빔(beam) 요소로 가정하고, 각 요소의 변형에 의한 변위는 형상 함수(shape function)과 절점 좌표(nodal coordinate)를 이용하여 정의하였다. 변형 변위를 이용하여 탄성 붐의 강성 행렬(stiffnes matrix)을 유도하고, 탄성 변위를 포함하는 위치 벡터를 이용하여 질량 행렬을 유도한다. 해상 크레인과 중량물로 이루어진 운동 방정식에 탄성 붐을 포함하여 유연 다물체계(flexible multibody system) 운동 방정식을 구성한다. 외력으로는 선박 유체정역학적 힘, 유체동역학적 힘, wire rope의 장력, 중력 그리고 계류력(mooring force)이 고려되었다. 먼저 요소의 개수를 변경하며 탄성 붐의 동적 거동을 시뮬레이션 하여, 유한 요소 정식화를 이용한 모델링의 타당성을 검증하였다. 그리고 해상 크레인과 중량물의 동적 거동 시뮬레이션에 탄성 붐 모델을 적용하였다.

• 대한기계학회논문집A
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• 제34권4호
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• pp.501-509
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• 2010

해상크레인은 크레인을 탑재한 선박으로서, 조선소에서 대형 블록이나 구조물의 탑재 및 해상 운송 작업에 사용된다. 본 논문에서는 해상크레인과 중량물의 전후 동요(Surge), 상하 동요(Heave), 종 동요(Pitch)에 대한 정적/동적거동을 분석하였다. 이 때, 유연 다물체계 동역학을 적용하여 해상크레인의 붐(boom)을 탄성으로 고려하였으며, 플로팅 프레임(floating frame)과 노드 좌표(nodal coordinates)를 사용하였다. 질량 행렬, 탄성 강성 행렬, 2 차 속도 벡터, 일반화 좌표 방향으로 작용하는 외력 등을 고려하여 모든 운동이 연성된 비선형 운동 방정식을 구성하였다. 외력으로는 비선형 유체정역학 힘, 선형화된 유체동역학 힘, wire rope 힘, 계류력이 고려되었다. 수치 해석을 위해 Hilber-Hughes-Taylor 방법을 비선형 운동방정식에 적용하였다. 정적 거동 분석을 통한 정적 평형 자세를 고려한 경우와 고려하지 않은 경우에 대해 결과를 비교하였으며, 수치 해석 방법에 대한 정적/동적 거동 분석 결과를 비교하였다.

• 동력기계공학회지
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• 제16권2호
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• pp.66-74
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• 2012

In this paper, the authors propose a new approach to control a barge type surface vessel. It is based on the Dynamic Positioning System(DPS) design. The main role of barge ship is to carry and supply the materials to the floating units and other places. To carry out this job, it should be positioned in the specified area. However sometimes the thrust systems are installed on it, and in general the rope control by mooring winch system is used. It may be difficult to compare the control performances of two types. If we consider this problem in point of usefulness, we can easily find out that the winch control system is more useful and applicable to the real field than the thrust control system except a special use. Therefore, in this paper we consider a DPS design problem which can be extended to the many application fields. The goal of this paper is twofold. First, the sliding mode controller (SMC) for positioning the our vessel is proposed. Especially, in this paper, a robust stability condition is given based on descriptor system representation. In the result, the sliding mode control law guarantees to keep the vessel in the defined area in the presence of environmental disturbances. And second, the thrust allocation problem is solved by using redistributed pseudo-inverse (RPI) algorithm to determine the thrust force and direction of each individual actuator. The proposed approach has been simulated with a supply vessel model and found work well.

• 수산해양기술연구
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• 제50권2호
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• pp.193-201
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• 2014

The sea cage in marine aquaculture might be varied such as on the stability and shape in the open sea by environmental factors. To evaluate the stability of net cage structures in the open sea, the physical and numerical modeling techniques were applied and compared with field observations. This study was carried out to analyse the stability and the volume loss which would have an effect on the fish swimming behavior in the octagonal pillar type fish cage under the open sea. As a results, the volume loss ratio of the fish cage as measured using a depth sensor was indicated a value of the 30.3% under the current velocity (1.1m/s). The fish cage should be consisted of a concrete block with a weight over 10 tons, a mooring rope diameter over 28mm PP, and a shackle of 25mm under the current speed of 1m/sec for reasonable stability.

• 대한조선학회논문집
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• 제31권1호
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• pp.22-31
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• 1994

해양 공간에 설치되어 유체의 흐름과 지형에 변화를 주며, 대상 수산 생물의 유집에 의한 생산 어장의 조성과 치어의 보호 육성을 도모하는 중효한 어장 시설인 인공어초의 기술 개발은 점차 다양화되어지고 있다. 부체부와 계류부로 구성되어 있는 부어초의 개발에 있어서는 부어초의 특성 및 안전상 계류시스템의 설계가 극히 중요한 부분이 된다. 이 논문에서는 부어초의 계류시스템에 많이 사용되어지는 나일론, 폴리에스터와 폴리에틸렌으로 이루어진 인조섬유로우프의 정적시험의 과정과 그 결과로서의 Creep거동 및 하중-인장 곡선을 얻었다. 특히 나일론 로우프의 경우 수중에서 20%내외의 강도 하락(Strength drop)이 관찰되며, Creep 시험 곡선은 대수시간 축(longerithmic time axis)상에서 직선을 유지하고, Flessner's formula와 평행한 결과를 얻었다.