• 해양환경안전학회지
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• 제28권2호
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• pp.307-313
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• 2022

지구 온난화와 기후변화에 대응하기 위해 국제적으로 재생 에너지의 개발이 확대됨에 따라 풍력발전의 비중도 점차 늘어가고 있다. 태양광발전에 비해 24시간 생산이 가능하지만 대형 풍력발전기를 대규모로 설치하기 때문에 주변의 레이더나 통신 장비들의 동작에 간섭을 일으키는 지에 대한 분석이 필요하다. 본 연구에서는 해상풍력 발전단지 외해를 항해하는 선박이 VHF 대역으로 조난 통신을 송신할 경우, 육지의 기지국에서 신호를 수신할 수 있는지를 분석하였다. 대상지역 주변의 수치지형도, 풍력발전기 캐드 모델, 풍력발전단지 배치도를 바탕으로 주변 해역 및 발전단지를 수치해석이 가능하도록 모델링하였다. 광범위한 지역에 대한 전파 분석에 적절한 고주파 해석기법 중 PO, SBR 기법을 적용한 전용 프로그램으로 전자파 간섭 여부를 분석하였다. 해상풍력 발전단지 외곽에서 송신한 VHF 대역 전자파에 대해 육상 기지국에서는 약간의 수신전력 저하는 있지만 기준치 이상의 전력을 수신하였다. 선박과 육상 기지국 사이의 가시선을 완전히 가리는 경우에 수신 전력의 저하가 발생하였으나, VHF대역이 파장이 길어 회절이나 반사 등의 효과로 육상 기지국까지 충분한 전파가 도달하는 것으로 판단된다.

• 한국가시화정보학회지
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• 제15권3호
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• pp.34-40
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• 2017

Within fractionating devices existing in separation and purification industries, sieve trays are widely used as tower internals and their choice is due to economical attractiveness. While operating a trayed distillation tower weeping phenomenon has a critical effect on the efficiency, in this case study a weeping phenomenon was undertaken by means of numerical model in a rectangular sieve tray. Eulerian-Eulerian Computational Fluid Dynamics (CFD) method was used and the obtained CFD results are in a good agreement with the experimental data in terms of weeping rate and pressure drop.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 춘계학술대회 초록집
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• pp.140-140
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• 2011

Korea's RPS, which requires that power generation companies obtain a minimum percentage of their generation by using renewable energy, will take effect in 2012. Based on the first-year law enforcement, generation companies have to satisfy 2% of RPS compliance ratio in 2012. Then, the required RPS compliance ratio will increase up to 10% in 2022. Thus generation companies need to construct power plants that utilize various types of renewable energy sources such as PV and wind power. This work is aimed to analyze the cost of such a renewable power source in terms of capital cost, capacity factor, and fuel cost. We provide the analytical expectation on the renewable power generation cost of 2012 focusing on PV, onshore/offshore wind, fuel cell, and IGCC, which are focused by government policy.

• 한국가시화정보학회지
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• 제14권1호
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• pp.27-32
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• 2016

The reduction of $CO_2$ emissions has been a key target in the Marine Industry since the IMO's Marine Environment Protection Committee published its findings in 2009. The representative emission index is termed as the EEDI (Energy Efficiency Design Index) for the new ships. Among various flow control techniques ever proposed, the air lubrication method is the one of most promising one in terms of practical applicability. The present study examines the basic characteristics of the flat plate test with intention of applying the air lubrication technology to the reduction of the resistance of a ship. Image analysis technique is proposed as a tool to quantify the effectiveness of the air lubrication method.

• 대한조선학회논문집
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• 제52권4호
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• pp.290-297
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• 2015

This research is focusing on the added resistance and seakeeping ability of the designed passenger ship with gooseneck bulb(Designed hull) which provide the improvement of resistance performance under calm water condition. By comparing the added resistances and seakeeping abilities of the reference hull and the designed hull form with gooseneck bulb, it is confirmed that there is little difference in the operational comfort and the reduction of ship speed. As a result, the applied gooseneck bulb in this study is verified for the applicability to medium-sized passenger ships with a good resistance performance.

• International Journal of Naval Architecture and Ocean Engineering
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• 제9권5호
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• pp.577-587
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• 2017

The recent IMO MEPC regulation on EEDI, EEOI and increased fuel cost has worsened the financial condition of the small and medium sized passenger ferry companies, and it is situated to acquire the economic ships with a pretty high resistance performance. The purpose of this research is to develop a design method on the efficient gooseneck bulb for the middle-sized passenger ferry operated in the Far East Asian seas. The hull forms are designed by varying the gooseneck bulb parameters to find the changes on the resistance performance according to the shape of bulb. The numerical series tests are made to derive the regression equation for estimating the resistance through analyzing the data statistically. This equation is set as an objective function, and then using the optimization algorithm searches for the optimal combination of the design variables. After a hull form is designed corresponding to optimized parameters.

• International Journal of Naval Architecture and Ocean Engineering
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• 제4권4호
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• pp.335-352
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• 2012

An underwater hull cleaning robot can be a desirable choice for the cleaning of large ships. It can make the cleaning process safe and economical. This paper presents a hydrodynamic design of an underwater cleaning robot and its evaluation for an underwater ship hull cleaning robot. The hydrodynamic design process of the robot body is described in detail. Optimal body design process with compromises among conflicting design requirements is given. Experimental results on the hydrodynamic performance of the robot are given.

• International Journal of Naval Architecture and Ocean Engineering
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• 제7권2호
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• pp.390-398
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• 2015

Energy-saving devices for 317K VLCC have been developed from a propulsion standpoint. Two ESD candidates were designed via computational tools. The first device WAFon composes of flow-control fins adapted for the ship wake to reduce the loss of rotational energy. The other is WAFon-D, which is a WAFon with a duct to obtain additional thrust and to distribute the inflow velocity on the propeller plane uniform. After selecting the candidates from the computed results, the speed performances were validated with model-tests. The hydrodynamic characteristics of the ESDs may be found in improved hull and propulsive efficiencies through increased wake fraction.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1997년도 봄 학술발표회 논문집
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• pp.89-96
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• 1997

Most civil engineering structures, such as highway bridges, towers, power plants and offshore structures suffer structural damages over their service lives caused by adverse loading such as heavy transportation loads, machine vibrations, earthquakes, wind and wave forces. Especially, if excessive load would be acted on the structure, general or partial stiffness should be degraded suddenly and service lives should be shortened eventually For realistic damage assessment of these civil structures, System Identification method using only structure dynamic response data with unknown input excitation is required and thus becoming more challenging problem. In this paper, an improved Iterative Least Squares method is proposed, which seems to be very efficient and robust method, because only the dynamic response data such as acceleration, velocity and displacement is used without input data, and no information on the modal properties is required. The efficiency and robustness of the proposed method is proved by numerical problems and real single span beam model test.

• International Journal of Naval Architecture and Ocean Engineering
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• 제6권1호
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• pp.175-185
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• 2014

This study presents the prediction of propagated wave profiles using the wave information at a fixed point. The fixed points can be fixed in either space or time. Wave information based on the linear wave theory can be expressed by Fredholm integral equation of the first kinds. The discretized matrix equation is usually an ill-conditioned system. Tikhonov regularization was applied to the ill-conditioned system to overcome instability of the system. The regularization parameter is calculated by using the L-curve method. The numerical results are compared with the experimental results. The analysis of the numerical computation shows that the Tikhonov regularization method is useful.