• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.4
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• pp.803-810
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• 1992

With increases in the rotational speed of hydraulic machine, studies on the hydrodynamic characteristics of supercavitating cascade are important on the view of flow analysis and design of fluid machinery. In the present paper, the complex functions of nonlinear theory corresponding to the flow of supercavitating cascade can be obtained by distributing singulary singulary points such as sources, vortexes and doublets on hydrofoil and free streamline. The numerical calculations on the closed wake model and semi-closed wake model are carried out in order to show the flow characteristics around the supecavitating cascade with finite with finite cavity length. As the result of this study, the flow characteristics such as lift, drag and cavitation coefficients are predicted by the flow conditions of supercavitating cascade in the fluid machinery.

• Journal of Navigation and Port Research
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• v.27 no.1
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• pp.55-61
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• 2003

The maneuvering equations of motion are derived to express the motion of a ship. The wave forces in the time domain analysis are generated from the frequency transfer function calculated by 3-D source distribution method. The linear wave forces whose periods are equal to those of incident waves and the nonlinear wave forces that make long period drift forces are computed for the simulation. The consideration of irregular waves and nonlinear wave force effects on the slew motion are carried on the analyzing the motion of ship in the regular and irregular waves.

• Journal of the Society of Naval Architects of Korea
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• v.29 no.1
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• pp.14-28
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• 1992

For a planar curve-sided paned with constant or linear density distributions of source or doublet in the singularity methods, Cantaloube and Rehbach(1986) show that the surface integral can be transformed into contour integral by using Stokes' formulas. As an extension of their formulations, this paper deals with a planar polygonal panel for which we derive the closed-forms of the potentials and the velocities induced by the singularity distributions. Test calculations show that the analytical evaluation of the closed-forms is superior to numerical integration(suggested by Cantaloube and Rehbach) of the contour integral. The compact and explicit expressions may produce accurate values of matrix elements of simultaneous linear equations in the singularity methods with much reduced computer tiome.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.13 no.1
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• pp.73-79
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• 2001

In this study, a submerged plate-type breakwater is considered, which is supported by elastic foundation. This breakwater makes use of wave phase interaction among the incident, diffracted and radiated waves. We apply a three-dimensional singularity distribution method within the linear potential theory in order to describe the wave field. The submerged plate is assumed to be rigid and the elastic support be a linear spring with constant stiffness. A typical rectangle plate is exemplified for numerical calculation. The thickness of the plate is carefully selected in order to guarantee the solution to be stable by checking the condition number of the system matrix. A parametric study is carried out for examining the effect of the stiffness of the elastic support on performance of the breakwater. We also examine the effect of the submerged depth.

• Journal of the Society of Naval Architects of Korea
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• v.39 no.2
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• pp.11-18
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• 2002

In this paper, the method calculating hydroelastic responses of very large floating structure close to a breakwater in waves is presented. The source-dipole distribution method is used to calculate the generalized radiation problem considering breakwater effects and the diffraction problem is analyzed by using the source-dipole distribution andvelocity potential continuation method. The response of a VLFS is approximated by anexpansion in terms of a free-free beam. Calculated model is a VLFS with 1000m in length in a sea with a straight breakwater. The vertical displacements and bonding moments around a VLFS are calculated by variations for distance between a VLFS and a breakwater and incident wave angle to know the effect of a breakwater.

• Journal of Power System Engineering
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• v.8 no.4
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• pp.49-56
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• 2004

To design very large ships, such as very large drillships, we have to estimate the hydroelastic responses of the very large ships in waves. A numerical procedure is described for estimating the hydroelastic responses of very large ships advancing with slow speed in waves. The developed numerical approach is based on a combination of the three-dimensional source distribution method and the finite element method, including fluid-structure interaction by regarding a very large ship as many hull elements connected with elastic beam elements. Numerical results are compared with experimental and numerical ones obtained in the literature. The results of comparison confirmed the validity of the proposed approach.

• Journal of Power System Engineering
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• v.14 no.5
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• pp.48-55
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• 2010

When a large ship is advancing in waves, ship undergoes the hydroelastic response, which has influences on structural stability and the fatigue destruction etc. of the ship. Therefore, to predict accurate hydroelastic response, it is necessary to analyze hydroelastic response including fluid-structure interaction. In this research, a ship is divided into many hull elements to calculate the fluid forces and wave exciting forces on each elements using three-dimensional source distribution method. The calculated fluid forces and wave exciting forces are assigned to nodes of hull elements. The neighbor nodes are connected with elastic beam elements. We analyzed hydroelastic responses, and those are formulated by using finite element method. Particularly, to estimate the influence of forward speed on the hydroelastic responses, we use two different methods : Full Hull Rotation Method(FHRM) and Sectional Hull Rotation Method(SHRM).

• Journal of Ocean Engineering and Technology
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• v.8 no.2
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• pp.80-92
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• 1994

The dynamic response characteristics of a floating ocean city are examined for presenting the basic data for the design of huge offshore structures supported by a large number of floating bodies in waves. The numerical approach which is accurate in linear system is based on combination of a three dimensional source distribution method, wave interaction theory and the finite element method of using the space frame element. The hydrodynamic interactions among the floating bodies are taken into account in their exact form within the context of linear potential theory in the motion and structural analysis. The method is applicable to an arbitrary number of three dimensional bodies having any individual body geometries and geometrical arrangement with the restriction that the circumscribed, bottom-mounted. Imaginary vertical cylinder for each body does not contain any part of the other body. The validity of this procedure was verified by comparing with experimental results obtained in the literature.

• The Transactions of the Korea Information Processing Society
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• v.4 no.12
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• pp.3200-3210
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• 1997

In image processing we encounter some tasks to detect ellipse or to discriminate the curves. LSM is well used to fit curves to ellipse but it can fail to fit correctly when fitting to defected one. To overcome this problem, we propose Modified LSM. Only 2-parameters among 5-paramaters are to be determined by LSM, while 3-parameters are to be calculated by the constrain that the curve must pass 3 given points. Those 3 points are selected by operator so as to have elliptic feature. Such proposed MLSM shows better result than genunal LSM in case when the ellipse is severely defected. and is proved to be good method for determing the human dentition.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2018.10a
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• pp.53-53
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• 2018

본 연구는 대승 경전에 나타난 식물의 수록 양상과 그 의미를 밝히는 연구의 세 번째 과정이다. 법화경은 천태종(天台宗)의 소의 경전(所依慶典)으로 우리나라에서 유통된 경전 가운데 최다 간행된 경전이며 화엄경과 함께 한국 교학의 중심이 된 경전이다. 연구 대상은 현존하는 법화경의 판본 가운데 구마라집(鳩摩羅什) 역 묘법연화경(妙法蓮華經, 이하 법화경, 7권으로 구성)에 수록된 식물이다. 본 연구에서는 식물 분류학적 실체는 물론 이 경의 중심 논지와 연관성이 큰 천화(天華, 하늘의 꽃)의 실체를 별도로 구명하여 식물수록의 특성과 차별성을 동시에 구명하고자 하였다. 1. 법화경에 나타난 식물의 수록 횟수와 식물의 종 수는 다음과 같았다. 법화경에는 총 27종의 식물이 수록되어 있었으며 이 가운데 목본은 16종(59.3%)이고 초본은 11종(40.7%)이었다. 식물수록 양상에 있어 특이점은 목본이 초본에 비해 상대적으로 높은 비중을 차지하고 있었다는 점이었다. 이러한 결과는 중심사상의 전달방식에 있어 비교 대상이 되는 다른 대승 경전과 차이가 있다는 점과도 무관하지 않았다. 실제로 비교 대상인 화엄경의 목본과 초본 비율은 각각 17종(48.6%)과 18종(51.4%)이었고 열반경은 각각 36종(45.6%)과 43종(54.4%)으로 목본과 초본의 수록 비율에 차이가 크지 않았다. 2. 법화경에 나타난 식물 27종은 총 20개 과에 분포되어 있었다. 수련과 3종, 콩과 3종, 물푸레나무과 2종, 뽕나무과 2종, 벼과 2종의 순이었다. 다수 과에 분포된 식물은 대부분 중심사상 전달의 매개체인 천화(하늘의 꽃)에 속하는 식물이었다. 3. '하늘의 꽃' 이라고 신성시되면서 이 경의 내용 전개에 있어 중요한 위치를 점하고 있는'천화(天華)'는 연꽃과 수련 종류를 지칭하는 식물이 중심이 되었으며 유용한 관상 및 조경, 향료 자원 및 목재 자원 식물이었다.