• 대한조선학회논문집
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• 제43권5호
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• pp.550-559
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• 2006

A design procedure for a ship with minimum total resistance was developed using a numerical optimization method called SQP(Sequential Quadratic Programming) and a CFD technique based on the Rankine source panel method with the nonlinear free surface boundary conditions. During the whole optimization process the geometry of the hull shape was represented based on the NURBS(Non-uniform rational B-spline) technique and the modification of the hull shape was controlled using the Bell-shaped distribution function to keep the fairness of the hull shape before and after the hull modification. The numerical analysis was carried out using 4000TEU container ship in the towing tank facility installed in the Pusan national university to know the validity of the developed algorithm for this study. As the results of the numerical analysis it proved that the resistance of the optimized hull is conspicuously reduced in comparison with the original hull in a wave-making resistance point of view.

• Journal of Advanced Research in Ocean Engineering
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• 제4권1호
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• pp.7-15
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• 2018

The submarine is an underwater weapon system which covertly attacks the enemy. Pressure hull of a submarine is a main system which has to have a capacity which can improve the survivability (e.g., protection of crews) from the high pressure and air pollution by a leakage of water, a fire caused by outside shock, explosion, and/or operational errors. In addition, pressure hull should keep the functional performance under the harsh environment. In this study, optimal design of submarine pressure hull is dealt with 7 case studies done by analytic method and then each result's adequacy is verified by numerical method such as Finite Element Analysis (FEA). For the structural analysis by FEM, material non-linearity and geometric non-linearity are considered. After FEA, the results by analytic method and numerical method are compared. Weight optimized pressure hull initial scantling methods are suggested such as a ratio with shell thickness, flange width, web height and/or relations with radius, yield strength and design pressure (DP). The suggested initial scantling formulae can reduce the pressure hull weight from 6% and 19%.

• 한국의류산업학회지
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• 제8권4호
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• pp.465-470
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• 2006

Walnut hull is a by-product from the Walnut tree, used as natural dyestuff from ancient times. This study was done to examine the effects of extractive conditions on the properties of walnut hull extracts for making efficient use of the walnut hull as a natural colorant. Aqueous extracts of walnut hull were prepared at various extractive concentration, temperature and time. Then they were characterized using UV-Vis. Spectrophotometer, FT-IR Spectrometer, Prep Liquid Chromatography, and Energy dispersive X-ray spectrometer. The aqueous extracts have two absorbency peaks of UV-Vis. Spectrum, shoulder type peak in the range of 270-280 nm and broad type band around 420 nm. Intensity of absorbency is increased with increase of extraction concentration and time. However, Boiling temperature extraction method showed the most efficiency of all. Intensity of absorbency is also affected by extraction pH. The Prep LC examined two kinds of isolated colorant with different molecular weight. FT-IR spectra of hull extracts showed an absorption band around $3400cm^{-1}$, the peaks at $1700-1600cm^{-1}$, which are characteristic of aromatic compounds with unsaturated ketone and benzene ring. It showed that the extraction contained some mineral ions, such as K, Ca, Si, Mg.

• Journal of Advanced Marine Engineering and Technology
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• 제37권4호
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• pp.391-398
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• 2013

선체 청소를 통해 선박에서 소비되는 연료량을 감소시킬 수 있으며 최근에는 이러한 작업을 산업용 로봇을 사용하여 수행한다. 선체를 청소하는 로봇에 있어서 안정적으로 선체에 부착되어 주행하는 것이 가장 중요하므로 본 연구에서는 안정적으로 선체 청소로봇을 구동할 수 있는 주행 제어시스템을 개발하였다. 이와 더불어 보다 편리하게 로봇을 운용할 수 있도록 주행 제어시스템에 작업자의 편의를 반영하여 주행 제어시스템을 구성하였다. 개발된 주행 제어시스템의 주행 제어성능과 편의성은 선체와 동일하게 제작된 구조물에서 실험을 통해 입증하였다.

• 한국항해항만학회지
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• 제32권8호
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• pp.583-588
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• 2008

활주형선은 고속 운항시 선저에 동적압력을 발생시켜 선체를 부상시킴으로서 저항이 감소하게 되어 고속의 항주가 가능하게 된다. 일반적으로 선저에 스텝을 적용한 선형은 일체형 활주형선에 비하여 고속 주행시 선저 공기공급에 따른 접수면 감소로 인하여 전체저항 감소에 따른 속도향상과 연비절감 효과가 있다. 본 논문에서는 고속 선형시험이 가능한 실 해역모형시험을 이용하여 선저 스텝개수에 따른 고속 Stepped Hull 선형의 저항성능을 비교, 분석하였다. 시험결과, 2개의 스텝을 가지는 선형이 최소저항 선형임을 확인할 수 있었다.

• 정보처리학회논문지:컴퓨터 및 통신 시스템
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• 제3권1호
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• pp.1-6
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• 2014

현재까지 컨벡스헐 (convex hull) 의 계산 알고리즘들은 주로 점 집합 (point set) 에 대해 연구가 수행되어 왔다. 본 논문에서는 이산 공간에서 다양한 반경을 갖는 구 집합에 대한 컨벡스헐을 근사하는 방법을 제시한다. 구 집합에 대한 컨벡스헐 계산은, 특히 단백질 분자의 구조적인 특성을 연구하는 여러 응용분야에서 계산 효율성을 증대시키기 위한 기반 기술이라 할 수 있다. 분자에 대응하는 구의 집합에 대해 복셀 맵 (voxel map) 자료구조를 적용하고 이를 이용하여 컨벡스헐을 계산하는 알고리즘을 제시한다. 제안된 방법은 GPU를 활용한 병렬처리를 수행하여 평균적으로 6,400개 이하의 구가 포함된 집합에 대해 40ms 이내에 컨벡스헐을 계산하는 성능을 보인다.

• 대한조선학회 특별논문집
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• 대한조선학회 2017년도 특별논문집
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• pp.59-62
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• 2017

Recently oil price has got lower, but energy efficiency has been considered as an important factor to minimize ship operational costs and reduce greenhouse gas emissions. For the reason, it is necessary that energy efficiency improvement for hull form design and operational performance reflect an understanding of the vessel's operational profile. Throughout the life of the vessel, this can lead to important economies of fuel, even if, in some cases, a small penalty can be taken for design condition. In the present paper, hull form was developed for 5,000TEU class container carrier at given operation profile. As a CFD result at several design point, optimized hull form has improved resistance performance in comparison with the basis hull form. To reducing the viscosity and the wave resistance at multi draft and multi speed, the hull form was investigated for Cp-curve, frame and local shape. Numerical study has been performed using WAVIS & Star-CCM+ and verified by model test in the towing tank.

• 품질경영학회지
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• 제45권3호
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• pp.393-401
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• 2017

Purpose: The purpose of this study is to propose retrofit measures for KDX-II KVLS hull crack, also, enhance safety and quality of ship. Also, this study suggest to how to retrofit about hull crack of the ship and how to improve operability of the ship. Methods: Retrofit measures of KDX-II KVLS hull crack reach a conclusion through global structure analysis and fatigue analysis. Concerned about thermal deformation due to welding around the KVLS, in addition to, verify to safety of KVLS. Results: Based on result of global structure analysis establish retrofit measures for KDX-II KVLS hull crack. Additionally, through fatigue analysis establish final retrofit measures. The results of retrofit measures are allowed both stress level and fatigue life. Conclusion: Retrofit measures for ship hull crack based on global structure analysis and fatigue analysis improves operability and quality of the ship. Especially, KDX-II ship is the best battleship in our country. Considering the importance of KDX-II, this study improves both Korea navy's combat power and ability to carry out the mission.

• 수산해양기술연구
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• 제40권1호
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• pp.17-22
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• 2004

This study was carried out at the CWC of Chosun university for the purpose of resistance performance improvement of planing hull, and the results of the tests were confirmed cooperatively with WJFEL. G/T 100 ton class planing hull form was selected, and the improvement of hull form including appendages were performed by using some model test techniques. The model test scope comprises resistance relative tests including wave profile observation, trim and sinkage measurement and flow visualization tests at full load and trial conditions for one bare hull and for two appended hulls. The final wedge and spray strip combined with improved hull form showed about 1.0 knot speed improvement at both of full and trial conditions, and outstanding improvement for fore wave phenomena.

• 한국전산유체공학회지
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• 제20권4호
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• pp.93-101
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• 2015

This paper provides numerical results of the simulation for the flow around the hull and the propeller of KCS model ship advancing in shallow water conditions. A finite volume method is used to solve the unsteady Reynolds averaged Navier-Stokes(RANS) equations, where the wave-making problem is solved by using a volume-of-fluid(VOF) method. The wave formed near the hull surface in shallow water conditions shows a deep trough dominant pattern that causes the loss of buoyancy followed by hull squat. The flow past the hull increases as the depth of water decreases. However, the axial flow velocity around the stern shows a reduction in magnitude by the effect of shallow water accompanied by the hull-propeller interaction. As a results, the thrust and torque coefficient increase about 8.3% and 6.2%, respectively for a depth of h/T=3.0 corresponding to a depth Froude number of $F_h=0.693$. The resistance coefficient increases about 11.6% at this Froude number condition.