• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.148-153
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• 2008

As the oil price is dramatically jumping up, the consumption of LNG is rapidly expanding and the size of LNG carriers becomes bigger. For LNG ships, the application of DF (Dual-Fuel) engines gradually increases because of high efficiency, which alternatively use diesel or BOG (Boil-Off Gas) from cargo tank as a fuel. The surplus BOG from LNG cargo tank should be exhausted by GCU or liquefied through the BOG reliquefaction system and returned back. This study focused into its operational characteristics through the process simulation using HYSYS and discussed details on the influence of the variations of some operational parameters such as a distribution ratio by the change of fuel mass flow into the DF engine.

• 한국해양공학회지
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• 제31권3호
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• pp.241-247
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• 2017

Plywood, which is created by bonding an odd number of thin veneers perpendicular to the grain orientation of an adjacent layer, was developed to supplement the weak points such as contraction and expansion of conventional wood materials. With structural merits such as strength, durability, and good absorption against impact loads, plywood has been adopted as a structural material in the insulation system of a membrane type liquefied natural gas (LNG) carrier. In the present study, as an attempt to resolve recent failure problems with plywood in an LNG insulation system, conventional PF (phenolic-formaldehyde) resin plywood and its alternative MUF (melamine-urea-formaldehyde) resin bonded plywood were investigated by performing material bending tests at ambient ($20^{\circ}C$) and cryogenic ($-163^{\circ}C$) temperatures to understand the resin and grain effects on the mechanical behavior of the plywood. In addition, the failure characteristics of the plywood were investigated with regard to the grain orientation and testing temperature.

• 한국해양공학회지
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• 제28권2호
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• pp.126-132
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• 2014

In this study, a method for analyzing the collision and interaction between ice bergy bits and a Mark III type liquid natural gas (LNG) carrier was considered, and the structural safety of a ship's hull and cargo containment system (CCS) was evaluated. In the analysis, a constitutive model implementing the strain rate dependant mechanical property was used to consider the typical material characteristics of ice rationally. A relatively simple and easy ice structure interaction analysis procedure, compared with the accurate but complicated FSI analysis scheme, was suggested. When the ice bergy bits collided with ship's side hull under the four assumed scenarios, the structural behaviors of the ship structure and LNG CCS were simulated by applying the suggested ice collision analysis procedure using the commercial hydro-code LS-DYNA. In addition, the effects of the shapes and colliding speed of the ice bergy bits on the ice-structure interaction and safety of the CCS were examined in detail.

• 대한조선학회 특별논문집
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• 대한조선학회 2007년도 특별논문집
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• pp.1-6
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• 2007

To improve productivity of the LNG carriers which are growing bigger and bigger, many researches are being carried out by shipyards. In this regard, we reviewed possible problems which could occur during the erection of 216K LNG carrier's motor/compressor room with all outfittings pre-installed. As a first item, the weights of hull and outfittings were precisely estimated to make sure that the erection is carried out within yard's capability. In the next place, deflection and safety of the structure were verified by FEM analysis. As a result, the erection was finished successfully and yard's productivity was also improved. This review is a good example which shows the importance of through study and preparation for improving yard's productivity which is already reached its limit.

• 대한조선학회논문집
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• 제42권5호
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• pp.448-457
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• 2005

The experiment was performed at the large wind tunnel of the Chungnam National University to measure the velocity distribution around the stern of a Liquefied Natural Gas Carrier model. The data, mean velocity vectors of turbulent shear flows at the stern and near-wake including the propeller plane, were obtained by a five-hole Pilot tube for the double body model fixed inside the wind tunnel test section. The present result of the double body model shows a close agreement with the result of the lowing tank experiment performed by the KRISO for the same ship model. The characteristics of the LNG stern flow are discussed based on the measured velocity distribution. The data can be very useful for the validation of some numerical methods in computational fluid dynamics.

• 한국산학기술학회논문지
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• 제22권3호
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• pp.94-100
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• 2021

멤브레인(membrane) LNG 운반선 화물창(cargo containment) 공사의 생산성 향상을 위해서는 공사 작업대인 비계 시스템(scaffolding system)의 설치 기간 및 공정 단축이 요구된다. 이를 위한 효과적인 방안으로 모듈의 탑재 단위를 기존의 2단에서 8단으로 대형화하자는 의견이 수렴되고 있다. 하지만, 모듈의 대형화로 인해 탑재 하중이 증가하면 메인 수직 파이프를 연결해주는 핀(pin)과 홀(hole) 주위에 국부 응력이 증가하여 재료의 항복응력을 초과하게 되는 문제점이 발생한다. 본 연구의 목적은 이러한 문제점을 해결하기 위해 트리즈(TRIZ)를 도입하여 새로운 대형 모듈의 탑재 방안을 수립하는 것이다. 본 연구에서는 트리즈의 여러가지 문제해결 도구 중 하나인 40가지 발명원리를 활용하는 방안을 채택하였다. 먼저 기술적 모순을 도출하고, 공학변수를 선정하였으며, 모순행렬을 활용하여 기술적 모순을 극복하기 위한 효율적인 발명원리를 선정하였다. 선정된 발명원리를 통해 일반해결안 및 특정해결안을 도출하였고, 구조해석을 통해 구조물에 발생하는 응력이 낮은 수준임을 확인하였다. 수립된 탑재 방안을 적용한 대형 모듈의 실제 탑재에 성공함으로써 트리즈의 유용성을 확인하였다.

• 한국기계가공학회지
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• 제7권4호
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• pp.76-81
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• 2008

A cryogenic butterfly valve is used to transfer the liquefied natural gas (LNG) which temperature is $-162^{\circ}C$. This valve is core part in the piping system using LNG. This paper performed coupling analysis using FEM to evaluate safety of cryogenic butterfly valve. Flow analysis is calculated numerically the CAE and CFD methods are useful to predict the thermal matter and the inner flow field of the valve. Thermal analysis and structural analysis used ANSYS Workbench.

• 해양환경안전학회지
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• 제4권2호
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• pp.13-24
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• 1998

This study aims at examining the safety of the would-be approach channel of LNG Terminal at Kwangyang Harbour, by utilizing Captains 2000 port-design simulator. Six competent shipmasters or navigators participated in this study. The developed model ship was a 70,200DWT (138,000m3) LNG carrier. The environmental conditions were maximum flood-and-ebb current condition and wind condition. To evaluate the navigational safety, two categories were analyzed, which were measures of vessel's proximity and shiphandler's subjective evaluations. With respect to the effects of the worst environmental conditions on transit safety, it was concluded that the would-be approach channel was safe on basis of the support of four tugs of 3,200hp or more and current speed of 0.5knots or less.

• International Journal of Naval Architecture and Ocean Engineering
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• 제12권1호
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• pp.856-867
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• 2020

This paper aims to provide the most useful method of determining an optimum LCB position and design direction of fore- and aft-body hull shape for a SLBV. It is known that the SLBV has a lower length-to-beam ratio, larger Cb and simpler stern shape designed for the installation of azimuth thrusters comparing to those of conventional LNG carriers. Due to these specific particulars of SLBV, the optimum LCB position was very different to that of conventional LNG carrier. And various approaches were applied to determine the optimum fore- and aft-body hull shape. The design direction for the optimum hull-form was evaluated as the minimization of the total resistance which includes the wave-making resistance and form-drag with numerical simulation.

• Journal of Advanced Research in Ocean Engineering
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• 제4권3호
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• pp.135-145
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• 2018

This paper deals with the added resistance of a ship in waves using computational fluid dynamics (CFD). The ship added resistance is one of the key considerations in the design of energy-efficient ship. In this study, the added resistance of a LNG carrier in head waves is computed using a CFD code to consider the nonlinearity and the viscous effects. The unsteady Reynolds Averaged Navier-Stokes equation (RANS) is numerically solved and the volume of fluid (VOF) approach is used to simulate the free surface flows. The length of incident wave varies from half the ship length to twice the ship length. To investigate the nonlinearity effect, both the linear wave condition and the nonlinear wave condition are considered. The heave and pitch motions are calculated along with the added resistance, and the wave contours are obtained. Grid convergence test is conducted thoroughly to achieve the converged motion and resistance values. The calculated results are compared and validated with experimental data.