Ha-Cheol Song

Optimal Block Transportation Path Planning of Transporters considering the Damaged Path

Nowadays, a transporter manager plans the schedule of the block transportation by considering the experience of the manager, the production process of the blocks and the priority of the block transportation in shipyard. The schedule planning of the block transportation should be rearranged for the reflection of the path blocking cases occurred by unexpected obstacles or delays in transportation. In this paper, the optimal block transportation path planning system is developed for rearranging the schedule of the block transportation by considering the damaged path. algorithm is applied to calculate the new shortest path between the departure and arrival of the blocks transported through the damaged path. In this algorithm, the first node of the damaged path is considered as the starting position of the new shortest path, and then the shortest path calculation is completed if the new shortest path is connected to the one of nodes in the original path. In addition, the data structure for the algorithm is designed. This optimal block transportation path planning system is applied to the Philippine Subic shipyard and the ability of the rapid path modification is verified.

Structural Integrity Evaluation for Interference - fit Flywheels in Reactor Coolant Pumps of Nuclear Power Plants

This study is concerned with structural integrity evaluations for the interference-fit flywheels in reactor coolant pumps (RCPs) of nuclear power plants. Stresses in the flywheel due to the shrinkage loads and centrifugal loads at the RCP normal operation speed, design overspeed and joint-release speed are obtained using the finite element method (FEM), where release of the deformation-controlled stresses as a result of structural interactions during rotation is considered. Fracture mechanics evaluations for a series of cracks assumed to exist in the flywheel are conducted, considering ductile (fatigue) and non-ductile fracture, and stress intensity factors are obtained for the cracks using the finite element alternating method (FEAM). From analysis results, it is found that fatigue crack growth rates calculated are negligible for smaller cracks. Meanwhile, the material resistance to non-ductile fracture in terms of the critical stress intensity factor(KIC) and the nil-ductility transition reference temperature RTinNDT are governing factors for larger cracks.

A Study for the Minimum Weight Design of a Coastal Fishing Boat

As most of small fishing boats made of FRP have been constructed by experience in Korea, some structural safety problems have been occurred occasionally. To improve the structural strength and reduce the costs for construction and operation, optimum design for small fishing boat was carried out in this study. The weight of fishing boat and the main dimensions of structural members are chosen as objective function and design variables, respectively. By the combination of global and local search methods, a hybrid optimization algorithm was developed to escape the local minima and reduce CPU time in analysis procedure, and finite element analysis was performed to determine the constraint parameters at each iteration step in optimization loop. Optimization results were compared with the real existing fishing boat, and the effects of optimum design were examined from points of view; structural strength, material cost, etc.

A Study on the Weight Reduction of Mid-sized Bulk Carrier based on the Harmonized Common Structural Rules

지속적인 조선경기의 침체를 극복하기 위해서는 제조원가를 줄이는 것뿐 아니라 연료절감형 선형을 개발하는 것은 매우 중요 한 일이다. 이를 위해서는 설계 및 생산 전 분야에 걸쳐 부단한 노력을 해야 하며, 그 중에서도 최적설계를 통한 선체 중량을 줄 이는 것은 매우 효과적인 방법이라 사료된다. 최적설계를 수행하 기 위해서는 해당 선박의 관련 규정에 대한 분석과 실제 설계에 대한 적용단계의 연구가 선행되어야 한다. 2015년 7월부터 기존의 CSR-BC (International Association of Classification Societies (IACS), 2012)와 CSR-OT가 통합되 어 통합공통구조규칙(H-CSR Harmonized CSR)이 발효되었다 (IACS, 2015). 따라서 향후 계약되는 모든 유조선과 산적화물선 은 이 새로운 규칙에 기반을 두어 설계를 수행하여야 하는데, 운 항되는 상선 중 절반 이상이 유조선과 산적화물선임을 고려한다 면 통합공통구조규칙의 발효는 향후 상선 시장에서 매우 중요한 안건이 될 것이다. 그동안 통합공통구조규칙에 대한 경향분석과 직접 요구치에 통합공통구조규칙 기반 중형 살물선의 중량 절감에

Development of an Automated Design Algorithm for the Longitudinal Members of Oil Tankers based on H-CSR

국제해사기구(IMO)는 국제사회의 온실가스 저감 노력에 부응 하여 선박의 탄소가스 규제를 논의하고 있다. 이는 지구환경변화 를 막기 위한 온실가스 규제에서 비롯되었으나 해운산업에 있어 서는 고연비화 경쟁을 촉발하는 원인이 되고 있다. 고연비 선박의 개발을 위해 저항성능이 좋은 선형, 효율이 좋 은 엔진뿐만 아니라 최적구획배치 및 구조설계를 통한 구조 경량 화 연계의 필요성이 점증되고 있다. 기존의 선체 구조 설계에 이용될 수 있는 최적 설계 기법에 대 한 연구 (Na, 2005; Shin, et al., 2006; Jo, 2010)는 꾸준히 진 행되어왔으며, 전통적인 구조해석법을 기반으로 한 중앙 횡단면 의 최소 중량 설계 및 건조비 설계 등을 기본 설계에 응용해 왔 다. 이러한 최적 구조설계 기법은 설계의 흐름상 확정된 구획배 H-CSR 기반 유조선 종강도 부재의 설계 자동화 알고리즘 개발 박찬임 .정솔1,† .송하철2 .나승수2 .박민철1 .신상훈3 .이정렬4 국립목포대학교 대학원 조선해양공학과 국립목포대학교 조선해양공학과 현대중공업 선박연구소 (사)한국선급 IT융합연구팀

Development of Automated Algorithm for Compartment Arrangement of Oil Tanker

Nowadays, optimum structural design techniques based on CSR have been developed and applied to the preliminary design stage focused on minimum weight and minimum construction cost of ship structure. Optimum structural design algorithm developed before could minimize weight and cost on fixed compartment arrangement. However, to develop more efficient design technique, a designer needs to combine optimized compartment arrangement with optimized ship structural design because compartment arrangement has a large effect on structural design according to the change of still water bending moment as a consequence of compartment arrangement change. In this study, automated algorithm for compartment arrangement of an oil tanker is developed to apply preliminary structural design. The usefulness of developed algorithm is verified with Aframax oil tanker constructed by STX shipbuilding Co.Ltd..

A Study of Optimum Shielding Gas Flow Rate in FCAW for Shipbuilding

FCAW(Flux Cored Arc Welding) is a widely used welding method in shipbuilding. It also conducts WPS(Welding Procedure Specification) requested by the classification variations of the factors which affect the quality on the welded area such as thickness of base metal, type of welding wire and shielding gas etc. which has to be satisfied. CO2 is commonly used as a shielding gas for FCAW due to the economic point of view. The amount of shielding gas is stated when classification certify WPS. However, the shielding gas is unnecessarily used at the shipyard leaning only on the welder`s experience as there are classification standards for using the shielding gas. It causes production cost to rise. Also recently, CO2 is a main contributor for global warming, and large amounts of CO2 are discharged into the atmosphere during shipbuilding processes without any filtration. Therefore it was confirmed by the security of the welded area as a result of conducting the destructive and non-destructive tests with setting up the factors and the standards by using the Taguchi method. Then the FCAW shielding gas`s amounts were calculated precisely when assembling a ship. It will be applied to cost reduction and prevention of environmental pollution at the shipyard.