• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.2
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• pp.171-179
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• 2013

The thermodynamic characteristics of a combined cycle applied with a topping cycle such as a trilateral cycle at relatively high temperatures and a bottoming cycle such as an organic Rankine cycle at relatively low temperatures have been theoretically investigated. This is an electric generation system used to recover the waste heat of the exhaust gas from a diesel engine used for the propulsion of a large ship. As a result, when the boundary temperature between the topping and the bottoming cycles increased, the system efficiencies of energy and exergy were simultaneously maximized because the total exergy destruction rate (${\sum}\dot{E}_d$) and exergy loss ($\dot{E}_{out2}$) decreased, respectively. In the case of a marine diesel engine, the waste heat recovery electric generation system can be utilized for additional propulsion power, and the propulsion efficiency was found to be improved by an average of 9.17 % according to the engine load variation, as compared to the case with only the base engine. In this case, the specific fuel consumption and specific $CO_2$ emission of the diesel engine were reduced by an average of 8.4% and 8.37%, respectively.

• Journal of the Society of Naval Architects of Korea
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• v.61 no.3
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• pp.185-199
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• 2024

Global warming impacts every corner of human life. Maritime transportation and shipbuilding industries are no exception. Recent counteraction in maritime industries is accelerating to meet the zero emission by 2050. Various alternative energy sources have been studied, and recent developments in Europe show that the windship, as a proven technology, can be an attractive candidate to solve the problem. In this paper, as the alternative transportation option, to infer the performances of modern windships, the non-dimensional ratios of past tall ships and windships are studied and reviewed. In addition, the ratios are compared to estimate the position of current and future windships under consideration. It is found that regarding the ratio distributions, the current windships being planned can be either wind-assisted propulsion ships or less fully functional windships than the past tall ships.

• 유체기계공업학회:학술대회논문집
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• 2002.12a
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• pp.47-53
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• 2002

The hydraulic design optimization and performance analysis of mixed-flow pumps for waterjet marine vehicle propulsion has been carried out using mean streamline analysis and three-dimensional computational fluid dynamics (CFD) code. In the present study the conceptual design optimization has been formulated with a non-linear objective function to minimize the fluid dynamic losses and then the commercial CFD code was incorporated to allow for detailed flow dynamic phenomena in the pump system. New designed mixed-flow model pump has been tested in the laboratory. Predicted performance curves by the CFD code agree very well with experimental data for a newly designed mixed-flow pump over the normal operating conditions. The design and prediction methods presented herein can be used efficiently as a unified hydraulic design process of mixed-flow pumps for waterjet marine vehicle propulsion.

• Journal of Power System Engineering
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• v.15 no.2
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• pp.78-83
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• 2011

This paper aims at investigation some operating characteristics and energy usage efficiency of a induction motor and a BLDC motor considering electric propulsion system in a small ship based on battery source. At first, performance curves of discharge voltage from the battery and current from each motor according to the load variations were analyzed. Next, variations of motor torque and rotational speed versus load change at each motor were analyzed. Finally, efficiency of energy usage of the battery and available navigation distance were compared each other. Through some comparisons and analyses, it was cleared that the BLDC motor is more suitable for the motor of the electric propulsion system in small ships based on battery source. It is expected that the results can be used as useful data for design of the electric propulsion system with batteries.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.1407-1412
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• 2004

The velocity and pressure fields of a ship's propulsion mechanism of Weis-Fogh type are studied by advanced vortex method. The wing of NACA0010 type and the channel are approximated by a finite of source and vortex panels, and the free vortices are introduced from the surface of their bodies. The viscous diffusion of fluid is represented by the core-spreading method. The velocity field is calculated on the basis of Biot-Savart law and the pressure field is calculated from the integration equation formulated by Uhlman. The flow fields of this propulsion mechanism are unsteady and complex, but the flow fields are clarified by numerical simulation.

• 기계와재료
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• v.21 no.4
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• pp.38-46
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• 2010

고온 고압의 부식 환경 하에서 사용할 수 있는 고내구성 재료 개발은 항공기와 선박의 추진체 및 발전기 등과 같이 고온부에서 작동하는 장치 설비의 수명 확보 및 안전성 보장을 위해 관련 산업계의 지속적인 연구 개발이 요구되고 있는 분야이다. 최근 세계 각국에서 발전소를 중심으로 한 새로운 고효율 에너지 생산 시스템화 계획이 구체화됨에 따라, 과거 한 종류의 연료 연소 방식으로부터 다양한 연료를 사용할 수 있는 시스템으로 전환함과 더불어 극심한 고온 산화 환경 변화에 유연하게 대응할 수 있는 소재 개발이 주요한 기술적 이슈로 부각되고 있다. 이와 같은 측면에서, 소재 '표면'의 기계적 열화를 극복하면서 생산 경쟁력을 갖춘 '새로운' 보호 코팅 기술은 가스 터빈 엔진 제조업체와 같은 장치 설비 제조 업체의 요소 기술 영역으로 자리매김 하고 있다.

• Journal of Power System Engineering
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• v.21 no.4
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• pp.70-76
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• 2017

This paper presents the development of a Gas Valve Train (GVT) control system which is the core equipment of LNG fueled vessels. Due to the increasing worldwide demand for echo friendly green ship products, domestic companies urgently require to develop a core equipments for the LNG fueled vessels to secure worldwide markets in marine engineering. A LNG fueled engine generally equips the GVT, a fuel supply system that steadily supplies clean high-pressure LNG to the engine. The GVT requires a safety operational control system that can prevent any gas leakage accident, and a system that monitors operation status in real time. Therefore, we introduces a development for GVT control and monitoring system design and the design was systematically performed by means of functional analysis and differentiation of foreign advanced products.

• Journal of the KSME
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• v.23 no.3
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• pp.153-156
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• 1983

최근 격변하고 있는 국제해운동정을 볼 때 정치적 측면에서 흔히 남북문제로 일컬어지고 있는 선후진국간을 치열한 경쟁문제, 공산국상선대의 활발한 진출, 각국의 자국선 보호주의의 강화문 제등이 산적해 있으며 선대절약형 경제성있는 선박으로 전환되고 있으며 대체에너지 개발에 따른 LNG, LPG,석탄전용선이 유망분야로 지목되어 선진해운국들은 서서히 이 분야로 선대편성을 시도하고 있는 점등, 국제해운환경은 복잡다난한 양상을 띄고 있는 것이다. 이러한 추세하에 1979년 제 2차 석유파동이후 격심한 불황속에 있는 해운계의 실정으로 미루어 이에 대처하기란 용이한 과제가 아닌 것이다. 여기에 정부와 업계가 혼연일체가 되어 국제경쟁력제고를 위한 제 발전전략이 적극 검토 추진되어야 함은 물론이고 우리의 목표가 기필코 달성되어 민족의 번영과 복지국가건립의 소망이 성취되기를 회원 여러분과 함께 기대하는 바이다.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.2
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• pp.369-376
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• 2021

The International Maritime Organization has developed the Energy Efficiency Design Index, an index related to carbon dioxide emissions, to enforce regulations on newly built ships. In this study, a new type of energy-saving device called the ring stator was used for 158k crude oil carriers, whose hull form was developed as a very thin after-body hull to reduce the resistance by delaying separation. The Energy-Saving Device (ESD) particularly involving the duct, is not adapted to the thin-after body hull form-like container ship. This new ring stator was developed considering these characteristics. A parametric study was conducted through Computational Fluid Dynamics (CFD) analysis using the Star-CCM+ program, and approximately 3.4 % improvement in propulsion efficiency was achieved. Further optimization investigations and experimental studies should be conducted in the future.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.1
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• pp.69-75
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• 2010

A model ship equipped with the Weis-Fogh type ship's propulsion mechanism, which is consisted of one wing in a squared channel, was constructed. Sailing and vibration tests of the model ship were performed with the opening angles in a pool. The results are summarized as follows. The thrust and the speed of model ship were the highest for the spring-type wing of which the opening angle is automatically controlled in one stroke. Moreover, these values were approximately reduced by 4% from $30^{\circ}$ opening angle to $15^{\circ}$ in order. The maximum amplitude and RMS values of the model ship were the lowest for the wing having the opening angle of $30^{\circ}$, but were the largest for spring-type wing. And in case of the same opening angle, these values were lower for the ship on sailing than that on stationary.