• Structural Engineering and Mechanics
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• 제61권6호
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• pp.737-746
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• 2017

The touch down zone (TDZ) and top connection point of the vessel are most critical part of fatigue damage in the steel catenary riser (SCR). In general, the linear soil model has been used to evaluate fatigue performance of SCRs because it gives conservative results in the TDZ. However, the conservative linear soil model shows the limitation to accommodate real behavior in the TDZ as water depth is increased. Therefore, the riser behavior on soft clay seabed is investigated using a nonlinear soil model through time domain approach in this study. The numerical analysis considering various important parameters of the nonlinear soil model such as shear strength at mudline, shear strength gradient and suction resistance force is conducted to check the adoptability and applicability of nonlinear soil model for SCR design.

• Structural Engineering and Mechanics
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• 제62권4호
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• pp.381-389
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• 2017

In the present study, the advanced procedure has been proposed to estimate higher accuracy of embedment of pipes that are installed on soft clay seabed. Numerical simulation by OrcaFlex simulation code was performed to investigate dynamic seabed embedment, and two steps, i.e., static and dynamic analysis, were adopted. In total, four empirical curves were developed to estimate the seabed embedment including dynamic phenomena, i.e., behaviour of vessel, environmental condition, and behaviour of nonlinear soil. The obtained results were compared with existing methods (named general method) such as design code or guideline to examine the difference of seabed embedment for existing and advance methods. Once this process was carried out for each case, a diagram for estimating seabed embedment was established. The applicability of the proposed method was verified through applied examples with field survey data. This method will be very useful in predicting seabed embedment on soft clay, and the structural behaviours of installed subsea pipelines can be changed by the obtained seabed embedment in association with on-bottom stability, free span, and many others.

• 대한조선학회논문집
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• 제37권4호
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• pp.1-10
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• 2000

일반 상선의 비선형 조파문제를 해석하기 위해 상방향 패널법에 기반을 둔 패널법을 개발하였다. 먼저 현재의 비선형 방법의 검증을 위해 많은 실험값이 존재하는 Series 60 선형에 개발된 방법을 적용하였다. 실제적인 응용의 경우로 KRISO 3600TEU 컨테이너선과 KRISO 300K 유조선에 개발된 방법을 적용하였다. 특히 두 상선이 유기하는 파계의 비선형성에 중점을 두고 계산된 파계를 KRISO의 실험값과 비교, 검증하였다. 현재의 비선형 방법은 Dawson의 방법이나 Neumann-Kelvin해와 같은 선형 방법에 비해 월등히 그 결과가 좋음이 확인되었다.

• 대한조선학회논문집
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• 제29권3호
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• pp.157-165
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• 1992

본 연구에서는 굽힘을 받는 평판의 특성을 다루었으며 평판중 특히 수밀 격벽판 및 디프탱크 격벽판에 대하여 각 선급의 강선 규칙에서 규정하고 있는 규정식의 이론적 배경에 대하여 해석하고, 각 선급의 강선규칙에서 규정하고 있는 격벽판에 대한 설계 규정식을 비교검토한 후 모델 선박을 선정하여 격벽판에 대한 3차원 상세구조해석을 실시하여 선급규정식의 적용범위를 밝힘으로서 새로운 규정식의 방향을 제시하였다.

• 한국군사과학기술학회지
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• 제22권6호
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• pp.815-823
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• 2019

A naval surface-to-air missile is an effective countermeasure against increasing threats of anti-ship missiles. Optimal operation is imperative for high survivability due to limited defense resources of a warship. This paper addresses a problem of optimal engagement to maximize the overall probability of intercept under Shoot-Look-Shoot tactics. The problem is formulated and analyzed with consideration of a realistic single-shoot probability model. The analysis shows that a global solution is achieved for some engagement scenarios. A numerical algorithm to optimize the overall probability of intercept is suggested. An illustrative example is provided to verify our results.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 추계학술대회논문집 II
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• pp.1300-1305
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• 2001

One of the main noise sources in cabin onboard ships is HVAC system. Up to now, the HVAC system designer manually calculates the HVAC system noise, or uses the program that is generally based on text user interface. In such a case, it is difficult to use the program and also to obtain the flow induced noise. In this study, the HVAC noise analysis program has been developed, which is based on GUI user interface that include 3.D modelling and model modification modules. For calculation of the insertion loss of HVAC system elements, NEBB experimental data and plane wave theory are used. And in order to obtain the flow rate information in each HVAC elements which is used to calculate the flow induced noise calculation, Global Converging Newton-Rapson Method is used.

• Journal of Ship and Ocean Technology
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• 제12권2호
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• pp.16-31
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• 2008

The lifting-surface programs have been used successfully in practice for the design and global performance prediction of the marine propellers. To predict the pressures on the blade for the strength analysis, the constant panel method has been a good alternative. To meet the need for more accurate information on the pressure near the tip region and the trailing edge of the blade, the higher order panel method (HiPan, hereinafter) based on a B-spline is developed and now available. However, there is an increasing demand to get the highly reliable unsteady behavior of the pressure near the tip region by the HiPan. The ultimate goal of our efforts is to develop the fully unsteady higher order panel code for the propeller. In the present paper, we will show the numerical procedure applicable to unsteady problems of the three dimensional hydrofoil in a sinusoidal gust and heave motions.

• 한국항만경제학회지
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• 제32권1호
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• pp.17-28
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• 2016

본 연구는 SNA(Social Network Analysis)를 이용하여 아시아 지역 크루즈 항로의 네트워크 구조와 항만의 중심성 파악을 연구의 목적으로 하였다. 크루즈 항로의 네트워크 분석을 위해 아시아 항만을 운항하는 크루즈 선사 항로의 데이터를 Cruise Lines International Association 보고서를 통해 수집하였으며, 이를 활용하여 크루즈 항로의 네트워크를 구성하였다. 아시아 크루즈항로의 구조분석결과, 노드 수는 249개, 링크 수는 54, 밀도는 0.009, 평균거리는 2.180으로 분석되었다. 네트워크 중심성 분석결과, 연결 중심성의 경우 Out degree와 In degree 모두 Singapore가 1위를 기록했으며, 매개 중심성 분석결과, Singapore가 1위로 분석되었다, 아이겐 벡터 중심성이 가장 높은 항만은 Hong Kong으로 분석되었으며, 그 뒤로 Ho Chi Minh, Singapore, Shanghai, Danang이 분석되었다. 국내항만인 Incheon, Busan, Jeju의 경우 연결 중심성, 매개 중심성, 아이겐벡터 지표 모두 경쟁 항만이라 할 수 있는 동남아지역 항만과 중국항만보다 순위가 낮은 것으로 나타났다.

• 통상정보연구
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• 제14권4호
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• pp.317-337
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• 2012

본 연구는 조선산업과 해운 발전을 위해 한국과 중국의 선박금융제도에 대해 비교하고 이를 바탕으로 문제점을 도출하고, 우리나라 선박금융제도의 발전방안 제시하였다. 2008년 글로벌 금융위기 이후 리먼브라더스의 파산 이전까지만 하더라도 유럽의 주요선진국이 독점하던 선박금융이 한국, 일본, 중국 등 상대적으로 강력한 금융시스템과 저금리를 바탕으로 아시아 지역으로 중심이 변화되고 있는 실정이다. 본 연구는 동북아 3국 가운데 가장 먼저 선박금융을 도입한 한국이 오히려 중국의 도전에 직면하고 있는 현재의 상황을 극복할 수 있는 대안이 무엇인지 연구하였다. 본 연구에서 한국의 선박금융의 문제점을 선박금융 조달의 한계, 전문 인력의 부족, 환리스크 상존, 관계자의 이해 부족을 제시하였으며, 이러한 문제점을 해결하기 위한 대응방안으로 선박금융전문기관의 설립, 금융산업에서의 전문인력 양성, 원화의 대외신임도 상승, 이해당사자간의 지속적 협의 등을 제시하였다. 우리나라는 아시아 최초의 선박펀드 도입국가이지만, 해운과 조선 및 선박금융의 유기적인 연결 속에서 중국 선박펀드의 성장과정을 눈여겨봐야 할 것이다.

• Ocean Systems Engineering
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• 제2권3호
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• pp.217-228
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• 2012

As the size of container ships continues to increase, not many existing harbors can host the super-container ship due to its increased draft and the corresponding dredging requires huge budget. In addition, the minimization of waiting and loading/offloading time is the most important factor in harbor competitiveness. In this regard, mobile-harbor concept has been developed in Korea to achieve much improved harbor capacity and efficiency. In developing the concept, one of the most important elements is the operability of crane between two or more floating bodies in side-by-side arrangement. The container ship is to be stationed through a hawser connection to an outside-harbor fixed-pile station with the depth allowing its large draft. The mobile harbors with smart cranes are berthed to the sides of its hull for loading/offloading containers and transportation. For successful operation, the relative motions between the two or more floating bodies with hawser/fender connections have to be within allowable range. Therefore, the reliable prediction of the relative motions of the multiple floating bodies with realistic mooring system is essential to find the best hull particulars, hawser/mooring/fender arrangement, and crane/docking-station design. Time-domain multi-hull-mooring coupled dynamic analysis program is used to assess the hydrodynamic interactions among the multiple floating bodies and the global performance of the system. Both collinear and non-collinear wind-wave-current environments are applied to the system. It is found that the non-collinear case can equally be functional in dynamics view compared to the collinear case but undesirable phenomena associated with vessel responses and hawser tensions can also happen at certain conditions, so more care needs to be taken.