• Bulletin of the Society of Naval Architects of Korea
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• v.26 no.3
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• pp.9-20
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• 1989

It is important to enhance the safety of ship structures as much as possible in order to prevent the disastrous collapse of structures. In fact, the strength problem of structures is closely related with the safety problem of structures. Recently, the direct calculation method using a rational approach based on the first principle is implemented into the structural design process instead of adopting empirical approach based on the rules. The structural designer have shown increased concern with the problem of adequacy of conventional design method based on the safety factor since it does not fully take into account some degree of variability of the applied loads on and the strength of ship structures. To deal with the analysis of structures effectively, it is necessary to have three stages being equally treated. The first one is load analysis, second one response analysis, third one safety analysis. For marine structures, most of research effort has been however put into the first and second stages. The third stage is normally done by simple procedures. Hence, the various probabilistic methods are compared in order to establish the reliability analysis techniques for ship structures. As a result, the advanced level 2 method is selected as a most effective and accurate reliability method. The validity of this method is further demonstrated by comparing the results with the conventional method for the problem of the longitudinal strength of hull girder of Ro-Ro ship.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.5
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• pp.531-542
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• 2017

The structural safety of small craft, such as steel ships and FRP ships, can be estimated using the measurement test of the hull plate thickness or the longitudinal bending strength test. A polyethylene boat is made using inexpensive HDPE and can be mass produced. The structural safety of a polyethylene boat cannot be guaranteed because a polyethylene boat hull is notspecified in the KR technical rules. The inspection procedure of sailing yachts and pleasure boats and drop test method of ISO standard 12215-5 propose the structural strength required for small crafts as the drop test height. Therefore, in this study, the drop test of a polyethylene boat hull was carried out based on the inspection procedure of a sailing yacht and pleasure boat and the drop test method of ISO standard 12215-5. The drop load was acquired by the drop acceleration ofa boat hull. Structural analysis and safety of a polyethylene boat were performed by the drop load and allowable stress criteria. The calculation results of the hull plate thickness by structural design specification of ISO standard 12215-5 showed that polyethylene boat hull was more than two times thicker than a steel ship hull and the boat hull determined by the inspection procedure of sailing yacht and pleasure boat and drop test method of ISO standard 12215-5 was more than 1.2 times thicker than the boat hull determined by structural design specification of ISO standard 12215-5. Therefore, inspection procedure of sailing yachts and pleasure boats and drop test method of ISO standard 12215-5 was much more conservative than the structural design specification of ISO standard 12215-5 and could be used as the structural design method of a polyethylene boat.

• Proceedings of KOSOMES biannual meeting
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• 2017.11a
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• pp.149-149
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• 2017

• Bulletin of the Society of Naval Architects of Korea
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• v.30 no.2
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• pp.8-10
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• 1993

선박에너지 개발을 위한 미래의 유력한 추진체로서 초전도 자력장을 이용한 선박을 들 수 있는데 이와 같은 경우에는 실험을 하기에는 비용이 엄청나게 소요되고 설비 자체가 복잡하기 때문에 CFD를 이용해서 초기 계\ulcorner을 구상하고 선체 주위의 유동장의 제어 및 기초 설계를 하여야 할 것이다. CFD계산을 통해 일반적으로 얻을 수 있는 것은 -압력 분포 -자유 표면 파고 -유속 분포 -유선 추적 -선체 표면의 응력 분포 -한계 유선 분포 -선미 와류 생성 과정 -선체 저항 계산 등으로 선형 개발에 필요한 기본 자료들이다. 여기서 CFD의 유용가치를 강조할 수 있는데 위의 많은 데이터를 실험을 통해서 얻으려면 막대한 경비와 노력이 투입되어야 한다. 또한 현재의 실험 시설로는 정량적으로 측정할 수 없는 부분도 일부 있다. CFD의 경우는 그러한 어려움은 없으나 꼭 필요한 것이 수치계산의 검증이다. 계산 결과의 유효성(validity)을 검증해야 한다는 의미이다. 계산은 실험을 통하여 반드시 비교 검토가 이루어져야 하며 이의 수단으로 선박 분 야에서는 Wigley 모형이나 Series 60와 같은 것들이 사용되고 잇다. 당 연구소의 저항추진연구 실에서는 CFD의 연구가 수년 전부터 소수의 인원을 중심으로 이루어져 왔다. 이와 관련하여 대표적인 몇 가지만 소개하고자 한다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2018.05a
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• pp.185-186
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• 2018

에어보트(Air boat)는, 판옥선처럼 선체 밑바닥이 편평한 형태로 되어있어 물위는 물론 일반 선박이 갈 수 없는 얕은 수면, 개펄, 빙상, 늪지수풀 위를 달릴 수 있는 모터보트의 한 종류이다. 선체상부 뒤쪽에 장착된 로터의 회전에 의한 풍력으로 추진되며, 로터 바로 뒤에 방향키가 있다. 선체 재질로는 스틸, FRP가 주로 사용되고 있으며 최근 알루미늄, 탄소섬유의 적용이 늘어나고 있다. 수상크루징, 낚시, 스쿠버 등에 활용되며, 선저의 독특한 형상으로 인해 군사용, 인명구조용, 수산물수송용 등으로도 사용된다. 이 연구에서는 12인승 비미니탑 에어보트를 설계, 제작하고 해상 시운전을 실시하였다. 또한 소음저감을 위해 머플러를 설계 제작하고, 35노트에서 75~78dB 수준으로 성능을 검증하였다.

• Bulletin of the Society of Naval Architects of Korea
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• v.31 no.4
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• pp.22-25
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• 1994

선체성능, 선박운항성능 및 기관성능의 현황파악과 예측을 하는 것은 선박설계자, 선박운항자 및 선박관리운영자에게 설계, 보선관리 및 용역관리상 대단히 중요하다. 선체성능의 전산원용예측에 관한 대부분의 문헌은 모형수조시험 및 공시해상시험의 자료를 수식화하는 데 집중하고 있다. 따라서 현재까지 자료의 수식화, 예측된 자료와 성능시험결과치의 상관기법 및 PC soft ware를 이용한 선박성능예측의 체계적 접근법 등에 관한 연구가 활발히 진행되어 왔다. 또한 선박의 Abstract Log Book의 자료 및 주기관 성능자료의 수식화, PC soft ware 개발에 의한 선박운 항성능 및 기관성능예측에 대한 연구가 역시 수행되고 있다. 이와 관련하여 본 고에서는 선체 성능(저항과 추진계수), 선박운항성능 및 주기관성능의 예측에 관하여 그 개요를 소개코져 한다.

• Journal of the Society of Naval Architects of Korea
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• v.29 no.1
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• pp.1-13
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• 1992

The objective of this study is to develop knowledge-based system for the preliminary design and midship section design of bulk carrier and to enhance the applicability of knowledge engineering in the field of Naval Architecture. First, expert system shell called E.1 is developed in C language. E.1 supports backward-chaining, automatic iteration procedure and reiterative inference mechanism for efficient application of knowledge-based system in structural design. Knowledge representation in E.1 includes IF-THEN rules, 'facts'and 'tables'. Second, knowledge bases for the principal particulars and midship section design are developed by experimental formula, design standard and experiential knowlege. Third, hybrid system combined this knowledge-based system with the optimization program of midship section is developed. Finally, the simplified design method utilizing the regression analysis of the optimum results of stiffened plate is developed for facilitating the design process. Using this knowledge-based system, the design process and results for Bulk carrier and stiffened plates are discussed. It is concluded that knowledge-based system is efficient for preliminary design and midship section design of the ship. It is expected that the performance of the CAD system would be enhanced if the better knowledge-base is accumulated in the E.1 tool.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.3
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• pp.309-316
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• 2011

Canoes are usually made from wood or FRP. However, today environment-friendly materials are preferred, and hulls made of FRP are prohibited in some countries. Polyethylene can be recycled and so is suitable for synthetic canoe construction. We used 3D Boat-Design to determine the hydrostatic properties of the canoe. Flow-structure coupled analysis was performed using ANSYS Workbench R12.1. The hull pressure and passenger weight were considered as canoe loading factors. The key parameters for the canoe are the design variables. The constraints are as follows: (1) The maximum stress must not exceed 50% of the polyethylene yield stress; and (2) the canoe weight must not exceed 50 kg. The optimal structural conditions were obtained by the response optimization process. The components of the canoe hull were manufactured from polyethylene pipes and joined by thermal fusion methods. Tests showed that the polyethylene canoe had better performance than existing canoes.

• Journal of the Society of Naval Architects of Korea
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• v.35 no.3
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• pp.54-61
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• 1998

This paper presents a prediction method of natural frequencies of vertical hull girder vibration based on design sensitivity analysis in case of design modification and the variation of loading condition. The resented method premises the vibration analysis by the transfer matrix method. Governing sensitivity equation is derived from the direct differentiation of state vector and transfer matrix to parameters and its transfer over all the hull girder elements. Derivatives of natural frequencies and mode shapes are determined by two trial calculation of the governing equation. Using the derivatives, the changes of natural frequencies and mode shapes can be predicted when mass and stiffness parameter's are changed. As results, it is possible to optimize ship structure as well as to avoid troublesome calculation in hull girder vibration analysis rationally and efficiently. To verify the accuracy and efficiency of the resented method numerical results obtained by both the sensitivity analysis and the ordinary reanalysis far a real ore/bulk carrier in case of the change of mass and stiffness parameters are compared.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.714-717
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• 2011

본 논문에서는 선체 블록의 운반 작업 중 발생하는 동적 하중 및 골리앗 크레인의 와이어로프와 선체블록 간의 동적 접촉력을 고려한 최적 러그 배치 시스템을 설계하고, 다물체계 동역학 커널과 외력 계산커널을 개발하였다. 다물체계 동역학 커널은 recursive formulation을 이용하여 운동 방정식을 구성하고, 외력 계산 커널은 비선형 유체정역학적 힘, 선형 유체동역학적 힘, 풍력, 계류력을 계산할 수 있다. 이를 이용해 블록에 작용하는 와이어로프와 블록 간의 간섭과 동적 접촉력을 계산하고, 그 결과를 이용하여 러그가 부착된 블록의 구조 해석을 수행하였다.