• International Journal of Naval Architecture and Ocean Engineering
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• 제7권1호
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• pp.142-156
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• 2015

A new method for ship Inner Shell optimization, which is called Parametric Inner Shell Optimization Method (PISOM), is presented in this paper in order to improve both hull performance and design efficiency of transport ship. The foundation of PISOM is the parametric Inner Shell Plate (ISP) model, which is a fully-associative model driven by dimensions. A method to create parametric ISP model is proposed, including geometric primitives, geometric constraints, geometric constraint solving etc. The standard optimization procedure of ship ISP optimization based on parametric ISP model is put forward, and an efficient optimization approach for typical transport ship is developed based on this procedure. This approach takes the section area of ISP and the other dominant parameters as variables, while all the design requirements such as propeller immersion, fore bottom wave slap, bridge visibility, longitudinal strength etc, are made constraints. The optimization objective is maximum volume of cargo oil tanker/cargo hold, and the genetic algorithm is used to solve this optimization model. This method is applied to the optimization of a product oil tanker and a bulk carrier, and it is proved to be effective, highly efficient, and engineering practical.

• 한국항해학회지
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• 제22권4호
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• pp.1-14
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• 1998

There are three basic modes of operation of ships: liner, tramp and industrial operations. Industrial operations, where the owner of the cargo, i.e. the industrial carrier controls the ships, abound in the shipment of bulk commodities, such as oil, chemicals and ores. Industrial carriers strive to minimize the shipping cost of their cargoes. This paper is concerned with the operational optimization problem of a fleet owned by major international oil company. The major oil company is a holding corporation for a group of oil producing, transporting, refining, and marketing companies located in various countries throughout the world. The operational optimization problem of the fleet is divided into two-phases. The front end corresponds to the optimization of transporting crude oil, product mix, and the distribution of product oil to meet market demand. The back end tackles the operational optimization problem of the fleet to meet the transportation demand derived from the front end. A case study is carried out with the H major oil company problem composed by reflecting the practices of an international major oil company. The results are summarized and examined in the point of optimization for the total operation of the H major oil company and the operational optimization problem of the fleet. The paper concludes with the remark that the results of the study might be useful and applicable in practices of these related decision problems.

• 한국항해항만학회지
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• 제34권3호
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• pp.189-194
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• 2010

최근 지구 환경 문제의 심각성이 대두되면서, 전과정 평가(Life Cycle Assessment)에 대한 선박 적용 연구가 조금씩 진행되고 있다. 본 논문에서는 선박 LCA 연구의 일환으로 선박 배기 가스 분석을 수행하였다. 이를 위하여 화물선에 대한 온실 배기 가스 배출 분석을 수행하였다. 대상 선박은 벌크선박과 유조선 등 2척을 모델로 삼았으며 과거 수년간의 실적 데이터를 분석하여 운항인벤토리 중 온실 배출가스의 정략적 데이터를 분석하였다. 이 분석을 통하여 화물선 운송 시 화물 1톤을 1마일 수송하는데 배출되는 배기 가스량의 분석을 시도하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1998년도 춘계학술대회 논문집
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• pp.67-70
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• 1998

In this work, the freestanding GaN single crystalline substrates without cracks were grown by hydride vapor phase epitaxy (HVPE). The GaN substrates, having a current maximum size of 350 $\mu\textrm{m}$-thickness and 10${\times}$10 $\textrm{mm}^2$ area, were obtained by HVPE growth GaN on sapphire substrate and subsequent mechanical removal of the sapphire substrate. A lattice constant of c$\_$0/=5.18486 ${\AA}$ and a FWHM of DCXRD was 650 arcsec for the single crystalline freestanding GaN substrate. The low temperature PL spectrum consist of excitonic emission and deep donor to acceptor pair recombination at 1.8 eV. The Raman E$_2$ (high) mode frequency was 567 cm$\^$-1/ which was the same as that of strain free bulk single crystals. The Hall mobility and carrier concentration was 283 $\textrm{cm}^2$/V$.$sec and 1.1${\times}$10$\^$18/ cm$\^$-3/, respectively. The freestanding and crack-free GaN single crystalline substrate suitable for the homoepitaxial growth of GaN, and the HVPE method are promising approaches for the preparation of large area, crack-free GaN substrates.

• 대한조선학회논문집
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• 제28권2호
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• pp.12-20
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• 1991

지금까지 선체구조 설계 관련 정보는 주로 도면을 통해서 전해져 왔으나 최신의 컴퓨터 관련 기술인 CAD 시스템이나 DBMS등을 이용하면 설계과정에서의 중복작업을 없앰으로서 설계생산성을 크게 높일 수 있다. 본연구에서는 선체구조 설계 관련 정보를 데이터 베이스관리시스템을 통하여 일관화하기 위해서 선체 중앙부 구조부재들의 배치형상과 속성정보들에 대한 데이터 모델링을 시도하였으며, 그 적용예로서 산적화물선의 중앙부 구조형상을 컴퓨터 그래픽을 이용하여 가시화 하였다. 데이터모델의 구조는 관계형으로 하였으며 선체구조의 접속관계정보를 이용하여 구조부재의 배치형상처리를 용이하게 하였다. 결과로서 나온 데이타 관계형 데이터베이스 관리시스템 'ORACLE'을 통해 저장되고 질의어를 통해 다른 시스템에서 직접 사용될 수 있음을 보였다.

• 대한조선학회논문집
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• 제28권2호
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• pp.77-94
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• 1991

일정속도로 항주하는 배에 치하여 생성되는 파를 유한차분법을 이용하여 수치적으로 시뮬레이션 하였다. 지배방정식으로는 3차원 운동량방정식(Euler Eq.)과 연속방정식을 사용하였으며, 직교 좌표 계상에서의 수치계산은 FTCS(forward time/central space)로 차분화하고 시간전진 방법(time marching scheme)으로 수행하였다. 좌표계로 staggered variable mesh system을 채용하여 기존의 계산조직을 개선하므로써, 유체 유동의 변화가 심한 선체주위에 계산 정도를 높이기 위하여 cell을 집중시켰다. 개선된 전산프로그램을 이용하여 Wigley, Series 60($C_{b}$=0.6), 그리고 MS416B 산적화물선 선형등을 대상으로 수치계산을 수행하였으며, 그 결과들을 실험값과 비교하였다.

• 대한조선학회논문집
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• 제52권2호
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• pp.161-169
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• 2015

According to SOLAS Regulation XII/6.5.3 and IMO GBS functional requirement(IMO, 2010), the structural redundancy of multi-bay stiffened panel in cargo area of bulk carrier should be provided enough in order to endure the initial design load though one bay of the stiffened panel is damaged due to plastic deformation or fatigue crack. To satisfy structural redundancy, Harmonized Common Structural Rules (hereinafter CSR-H, IACS, 2014) proposed to use 1.15 instead of 1.0 for buckling usage factor of stiffened panel in cargo area. This paper shows that buckling usage factor in CSR-H for structural redundancy is somewhat conservative considering the ultimate strength calculated by using nonlinear FEA for the damaged condition which is only one bay's plastic deformation due to colliding by weigh object like a bucket. Also, this paper presents that increasing of plate thickness only is more effective to get enough structural redundancy.

• 대한조선학회논문집
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• 제46권2호
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• pp.179-188
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• 2009

WIG crafts are a high speed vessel with features of dynamic supported craft. These crafts, which are predominantly of light weight and operate any substantially greater speeds than conventional craft such as bulk carrier, tanker, container ship, etc., could not be accommodated under traditional maritime safety instruments. It means that there is the need for risk and safety levels to be assessed on a holistic basis, recognizing that high levels of operator training, comprehensive and thoroughly implemented procedures, high levels of automation and sophisticated software can all make significant contributions to risk reduction. To response this requirement, the Interim Guideline for WIG craft(MSC/Circ.1054) were developed in the view of the configuration of WIG craft, which fall between the maritime and aviation regulatory regimes. This paper reviews a safety assessment process and methodology to be used in the design phase of a new ship. The process and methodology is based on the risk-based approach and is applied to safety assessment in concept development phase of small WIG craft in the 20-person class.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.268-268
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• 2010

The performance dependence of the P3HT:PCBM based bulk hetero-junction (BHJ) organic solar cells (OSCs) on the electrical and the optical properties of amorphous InZnSnO (a-IZTO) electrodes as a difference in film thicknesses are examined. With an increasing of the a-IZTO thickness, the series resistance ($R_{series}$) of the OSCs is reduced because of the reduction of sheet resistance ($R_{sheet}$) of a-IZTO electrodes. Additionally, It was found that the photocurrent density ($J_{sc}$) and the fill factor (FF) in OSCs are mainly affected by the electrical conductivity of the a-IZTO anode films rather than the optical transparency at thinner a-IZTO films. On the other hand, despite the much lower $R_{series}$ comes from thicker anode films, the dominant factor affecting the $J_{sc}$ became average optical transmittance of a-IZTO electrodes as well as power conversion efficiency (PCE) in same device configuration due to the thick anode films had as sufficiently low $R_{sheet}$ to extract the hole carrier from the active material.

• International Journal of Naval Architecture and Ocean Engineering
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• 제12권1호
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• pp.414-427
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• 2020

The finite element method is used to simulate the navigation of an ice-area bulk carrier in broken ice fields. The ice material is defined as elastic, and the simulations are accomplished at four model speeds and three ice concentrations. The movements of ice floes in the simulation are consistent with those in the model test, and the percentage deviation of the numerical ice resistance from the ice resistance in the model test can be controlled to be less than 15 %. The key characteristics of ice loads, including the average ice loads, extreme ice loads, and characteristic frequency, are analyzed thoroughly in a comprehensive manner. Moreover, the effects of sailing speed and ice concentration on the ice loads are analyzed. In particular, the stress distribution of ice floes is presented to help understand how model speed and concentration affect the ice loads. The "ice pressure" phenomenon is observed at 90 % ice concentration, and it is realistically reflected both in the time―and frequency―domain ice force curves.