• 대한조선학회논문집
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• 제43권1호
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• pp.103-118
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• 2006

At the initial design stage, the generation process of the production material information of a building block and the simulation process of the block erection, which are required to perform the production planning and scheduling, have been manually performed using 2D drawings, based on the data of parent ships, and subjective intuition from past experience. To make these processes automatic, the accurate generation method of the production material information and the convenient simulation method of the block erection based on the initial hull structural model(3D CAD model), were developed in this study. Here, the initial hull' structural model was generated from the initial hull structural CAD system early developed by us. To evaluate the developed methods. these methods were applied to corresponding processes of a deadweight 300,OOOton VLCC. As a result. it was shown that the production material information of a building block can be accurately generated and the block erection can be conveniently simulated in the initial design stage.

• International Journal of Naval Architecture and Ocean Engineering
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• 제9권4호
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• pp.373-381
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• 2017

A Collaborative Optimization (CO) methodology for ring-stiffened composite material pressure hull of underwater vehicle is proposed. Structural stability and material strength are both examined. Lamination parameters of laminated plates are introduced to improve the optimization efficiency. Approximation models are established based on the Ellipsoidal Basis Function (EBF) neural network to replace the finite element analysis in layout optimizers. On the basis of a two-level optimization, the simultaneous structure material collaborative optimization for the pressure vessel is implemented. The optimal configuration of metal liner and frames and composite material is obtained with the comprehensive consideration of structure and material performances. The weight of the composite pressure hull decreases by 30.3% after optimization and the validation is carried out. Collaborative optimization based on the lamination parameters can optimize the composite pressure hull effectively, as well as provide a solution for low efficiency and non-convergence of direct optimization with design variables.

• 한국산학기술학회논문지
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• 제14권3호
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• pp.1045-1053
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• 2013

플레저 보트나 요트는 FRP나 알루미늄으로 제작되고 있으나 FRP는 해양환경오염으로, 알루미늄은 낮은 가격 경쟁력으로 인하여 해당 제품의 시장 지배력이 약화되고 있다. 따라서 본 연구에서는 선체를 폴리에틸렌으로 제작하여 일본소형선박검사사무규정세칙에서 제안하고 있는 소형선체에 대한 구조 안전성 평가 방법을 통하여 폴리에틸렌 선체의 구조 안전성을 확인한 결과, 폴리에틸렌 보트가 FRP 보트보다 매우 높은 구조 안전성을 보였다.

• 한국가구학회지
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• 제10권2호
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• pp.17-27
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• 1999

As a countermeasure to reach self-sufficiency for wood supply and demand, we have to develop wood substitutes. Rice hull is the cheapest fiber material we can get in Korea, What is better the yield of rice hull amounts to 1 million tons per year. Before carrying out this study, new ecomaterial rice hull board for housing materials was developed successfully. In order to evaluate whether the rice hull board with or without bioceramic treatment is suitable for housing materials, we studied the environmental effect of the above materials in comparison with the polycarbonate, stainless, or concrete on the adaptation (body weight, water/feed consumption, general signs, urinalysis, autopsy, etc) and the reproduction(litter size, newborn adaptation, etc)of mice. In conclusion, the concrete cage was the worst in the adaptation and so was the stainless steel cage in the reproduction. The rice hull board cage with or without bioceramic treatment was superior or equivalent to other material cages from the standpoints of the adaptation and reproduction.

• Journal of Magnetics
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• 제16권2호
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• pp.114-119
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• 2011

This paper presents a magnetization modeling method combined with material sensitivity information to identify the unknown magnetization distribution of a hull and improve the accuracy of the predicted fields. First, based on the magnetization modeling, the hull surface was divided into three-dimensional sheet elements, where the individual remanent magnetization was assumed to be constant. For a fast search of the optimum magnetization distribution on the hull, a material sensitivity formula containing the first-order gradient information of an objective function was combined with the magnetization modeling method. The feature of the proposed method is that it can provide a stable and accurate field solution, even in the vicinity of the hull. Finally, the validity of the method was tested using a scale model ship.

• 한국환경보건학회지
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• 제21권1호
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• pp.56-67
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• 1995

This study was carried out to observe how composting reaction proceed in the optimum composting condition and to understand the characteristics of final compost, when swine feces was amended with different bulking material. Sawdust, rice straw, and rice hull were selected as bulking materials and each of these was mixed with swine feces to obtain the optimum range of moisture contents and C:N ratio. To grasp the influence of newspaper on cornposting reaction when it flew into the composting site intentionally or accidentally, another composting reaction using newspaper as a bulking material was studied. In this experiment, raw material mixes containing the same amount of organic materials were put into 4 composting reactors and composted in the same environmental condition for 3 weeks from Aug. 1, 1994 to Aug. 22, 1994. The followings are the main results of this study. 1. The maximum temperatures reached at during cornposting reaction were 53.8$\circ$C, 51.9$\circ$C, 52.7$\circ$C, and 52.1$\circ$C in the reactor using sawdust, rice straw, rice hull, and newspaper as a bulking material respectively: Thermophilic temperatures were maintained for 72, 108, 108, and 111 hours in each reactor. Mean temperatures of reactors using sawdust, rice straw, rice hull, or newspaper as a bulking materials were 39.7$\circ$C, 39.5$\circ$C, 41.3$\circ$C, and 40.3$\circ$C, but no significant difference between these mean temperatures was observed(p>0.05). Each composter showed significant difference from room temperature(p<0.01), and the mean difference between them was 9.4$\circ$C. 2. Ash contents of each reactor increased rapidly in order of rice straw, rice hull, newspaper, and sawdust according to the pattern of second order function. This rate of increase seemed to result from structural characteristics of a bulking material. The absolute values of second order coefficient of these regression functions were 0.0199, 0.0159, 0.0157, and 0.0144 in each reactor using rice straw, rice hull, newspaper, or sawdust as a bulking material. 3. C:N ratio decreased as the reaction proceeded. Degree of decrease was in order of rice straw, rice hull, newspaper, and sawdust. This sequence was consistent with the increase rate of ash content. The ratios of initial C:N ratio to final C:N ratio were 0.45, 0.53, 0.64, and 0.75 in each reactor using rice straw, rice hull, newspaper, and sawdust as a bulking material respectively. From this ratios, it was possible to infer that all the composting reactions were completed. 4. Fertilizer content containing in the final compost was 1.61~2.20% of N, and 0.35~0.54% of P in dry weight base. According to the classification standard for compost constituent by Higgins, all composts had the intermediate grade of N, but below the low grade of P excepting the newspaper amended compost(fall into the range of the low grade). 5. Heavy metal contents contained in the composts were analyzed. In case of Cd, the range of 0.58~1.11 $\mu$g/g was observed, and in case of Pb, the range of 24.76~39.53 $\mu$g/g was observed(in wet weight base). These values are below the permissible heavy metal level for compost of foreign countries.

• 해양환경안전학회지
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• 제5권2호
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• pp.99-111
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• 1999

The object of this study is to get the superior double hull structure to its crashworthiness against collision comparing absorbed energy capacities of its various types with each other, varying material properties, collision positions and velocities, and structural arrangements such as double hull width, web and stringer spaces, etc. Local absorbed energy capacities, failure behaviors and damage extents of their members are also considered during collision in addition to the estimations of their global ones. This paper describes a series of numerical simulations of collisions between DWT 45,000 oil tanker(struck ship) and DWT 10,500 rigid one(striking ships) using Hydrocode LS/DYNA3D. Collisions are assumed to occur at the middle of struck ship with striking one moving at right angle to its centerline. The following remarks were obtained through this study: More flexible the double hull structure is, much superior its crashworthiness against collision is. The increment of double hull width does not give much influence than other factors do. The exact use of material property such as failure strain is also important on the numerical simulation of collision.

• 한국산학기술학회논문지
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• 제16권12호
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• pp.8447-8454
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• 2015

레저 보트 선체의 구조설계규격과 재료는 ISO 12215-5에 규정되어 있으며 선체 전장이 2.5m이상 24m미만이면서 선체재료가 강, 알루미늄, FRP등에 대해서만 적용할 수 있다. 따라서 선체 전장이 2.5m이하이거나 선체 재료가 ISO 12215-5의 규정 재료이외인 레저 보트인 경우 ISO 12215-5의 구조설계규격을 적용시킬 수 없고 ISO 12215-5의 부속서에 규정된 낙하시험만으로 구조 신뢰성을 확보할 수 있다. 그러나 선체낙하시험은 제작된 선체에 대하여 적용하는 것은 가능하나 선체를 구조설계단계에서 적용하는 것은 상당한 설계 및 시험 비용등을 초래하므로 현장 적용성이 떨어진다. 따라서 본 연구에서는 이러한 문제점을 극복하기 위하여 일본 소형 선박 검사 사무 규정 세칙에서 제안하고 있는 선체의 종굽힘강도시험규격을 폴리에틸렌 보트 선체의 구조 설계에 응용하여 ISO 12215-5의 비선급표준재료로 제작된 폴리에틸렌 보트의 종굽힘강도시험규격의 허용 설계 변위 기준을 제안하였다.

• 대한조선학회 특별논문집
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• 대한조선학회 2008년도 특별논문집
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• pp.46-53
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• 2008

Recently, the synthetic material stern tube bush has been applied by ship owner's requirement because the synthetic material has a merit. That is to say, when stern tube seal is damaged and sea water comes into stern tube, it can work without problem because of water lubricating property. However, the material also has a demerit of temperature rise problem when some factors meets on synthetic material, for example, not sufficient lubrication oil supply and not proper shaft alignment and so on. As known in the world, the RAILKO bush is rampant for synthetic material by some ship owner because of the above mentioned reason. However, the bush has several accidents on large container vessel. Unfortunately or fortunately our yard has a chance to apply the RAILKO bush owing to requirement of specific ship owner. Therefore, it is much more required to approach the accurate shaft alignment analysis. In line with this reason, we had a shaft alignment calculation considering hull deformation and hull flexibility (hull stiffness). Also, in the calculation, we had considered dynamic condition which is reflected he propeller thrust forces and moments and oil film stiffness on the shaft alignment calculation. According to he shaft alignment calculation, bearing slope was applied on the tern tube bush and was measured. The RAILKO bush should be applied the running in procedure according to maker's recommendation for performing the oil film on the bush surface. Finally, the vessels were delivered successfully without any problem with AILKO bush as shown on his paper.

• Structural Engineering and Mechanics
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• 제15권2호
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• pp.225-238
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• 2003

In the present study, the finite strip analysis of a box girder to simulate a ship's hull model is carried out to investigate its inelastic post-buckling behavior and to predict its ultimate flexural strength. Residual stresses and initial geometrical imperfections are both considered in the combined material and geometrical nonlinear analysis. The von-Mises yield criterion and the Prandtl-Reuss flow theory of plasticity are applied in modeling the elasto-plastic behavior of material. The Newton-Raphson iterative process is also employed in the analysis to achieve convergence. The numerical results agree well with the experimental data. The effects of some material and geometrical parameters on the ultimate strength of the structure are also investigated.