• 한국태양에너지학회 논문집
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• 제35권5호
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• pp.11-19
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• 2015

In this paper, EP-Kalina cycle applying liquid-vapor ejector and motive pump is newly proposed. In this EP-Kalina cycle, the liquid-vapor ejector is used to increase pressure difference between inlet and outlet of the turbine. Also the motive pump enhances the performance of liquid-vapor ejector, resulting in increase of system efficiency of OTEC cycles. The comparison cycles in this study are basic, Kalina, EKalina and EP-Kalina ones. The pump work, net power, APRe, APRc, TPP and system efficiency of each cycle are compared. In case of net power, EP-Kalina cycle is lowest among the cycles due to the application of the motive pump. But, the net power difference of cycles seems to be minor since the pump work of cycles is merely about 1kW, compared to turbine gross power of 20kW. The system efficiency of EP-Kalina cycle shows 3.22%, relatively 44% higher than that of basic OTEC cycle. Therefore, the system efficiency is increased by applying the liquid-vapor ejector and the motive pump. Additional performance analysis is necessary to optimize the proposed EP-Kalina cycle.

• 동력기계공학회지
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• 제15권2호
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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.

• 대한조선학회논문집
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• 제53권4호
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• pp.266-274
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• 2016

Many researchers have been trying to improve the propulsion efficiency of a propeller. In this study, the numerical analysis is carried out for the POW(Propeller Open Water test) performance of a propeller equipped with an energy saving device called PHVC(Propeller Hub Vortex Control). PHVC is aimed to control the propeller hub vortex behind the propeller so that the rotational kinetic energy loss can be reduced. The unsteady Reynolds Averaged Navier-Stokes(URANS) equations are assumed as the governing flow equations and are solved by using a commercial CFD(Computational Fluid Dynamics) software, where SST k-ω model is selected for turbulence closure. The computed characteristic values, thrust, torque and propulsion efficiency coefficients for the target propeller with and without PHVC and the local flows in the propeller wake region are validated by the model test results of KRISO LCT(Large Cavitation Tunnel). It is concluded from the present numerical results that CFD can be a good promising method in the assessment of the hydrodynamic performance of PHVC in the design stage.

• 한국산업융합학회 논문집
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• 제26권3호
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• pp.401-409
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• 2023

Oscillating water column (OWC) type wave power generator system is a power generation system that uses wave energy, a sustainable and renewable energy source. Irregular cycles and wave heights act as factors that make it difficult to secure generation efficiency of the wave power generator system. Recently, research for improving power generation efficiency is being conducted by applying digital twin technology to OWC type wave energy converter system. However, digital twin using sensor data can predict erroneous performance due to uncertainty in the sensor data. Therefore, this study proposes an uncertainty analysis method for sensor data which is used in digital twin to secure the reliability of digital twin prediction results. Uncertainty quantification considering sensor data characteristics and future uncertainty information according to uncertainty propagation were derived mathematically, and confidence interval estimation was performed based on the proposed method.

• Journal of Advanced Marine Engineering and Technology
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• 제38권4호
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• pp.502-507
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• 2014

본 논문에서는 혼합작동유체를 해양온도차발전에 적용하였을 때에 그에 따른 사이클의 성능특성에 대해 연구를 수행하였다. 다양한 혼합작동유체 중 본 논문에서는 R32/R152a를 해양온도차발전에 적용하였다. 사이클로는 기존의 밀폐형사이클, 암모니아/물 혼합물에 적용하고 있는 칼리나 사이클에 대해 시뮬레이션 해석을 수행하였고, 온열원의 온도는 $26^{\circ}C$, 냉열원의 온도는 $5^{\circ}C$를 적용하였다. R32를 적용한 밀폐사이클의 출력은 22kW, 사이클의 효율은 2.02%를 보였다. 혼합작동유체를 적용하였을 때에 R32/R152a(90%:10%)의 출력은 29.93kW, 사이클 효율은 2.78%로 기존의 단일 냉매보다 36%, 사이클효율은 37%상승함을 확인 하였다. 칼리나 사이클 또한 위와 같은 방법으로 연구를 수행하였다.

• 한국해양공학회지
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• 제37권5호
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• pp.181-189
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• 2023

The fuel consumption of marine diesel engines holds paramount importance in contemporary maritime transportation and shapes energy efficiency strategies of ocean-going vessels. Nonetheless, a noticeable gap in knowledge prevails concerning the influence of ship hull conditions and propeller roughness on fuel consumption. This study bridges this gap by utilizing artificial intelligence techniques in Matlab, particularly convolutional neural networks (CNNs) to comprehensively investigate these factors. We propose a time-series prediction model that was built on numerical simulations and aimed at forecasting ship hull and propeller conditions. The model's accuracy was validated through a meticulous comparison of predictions with actual ship-hull and propeller conditions. Furthermore, we executed a comparative analysis juxtaposing predictive outcomes with navigational environmental factors encompassing wind speed, wave height, and ship loading conditions by the fuzzy clustering method. This research's significance lies in its pivotal role as a foundation for fostering a more intricate understanding of energy consumption within the realm of maritime transport.

• Journal of Advanced Marine Engineering and Technology
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• 제33권4호
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• pp.484-496
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• 2009

The strengthened regulations for atmospheric emissions from ships like MARPOL Annex VI have caused a necessity of new, alternative power system in ships for the low pollutant emissions and the high energy efficiency. This paper attempts to investigate the configuration of SOFC/GT hybrid power system for LNG tanker taking into account the safety and to analyze the influence of design parameters on the system performance. The simulation results provide the basic data for the design and efficiency improvement of SOFC/GT hybrid system and indicate the guidelines for the safe system operation.

• 해양환경안전학회:학술대회논문집
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• 해양환경안전학회 2017년도 공동학술발표회
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• pp.52-52
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• 2017

• Journal of Advanced Marine Engineering and Technology
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• 제33권2호
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• pp.233-243
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• 2009

The strengthened regulations for atmospheric emissions from ships like MARPOL Annex VI have caused a necessity of new, alternative power system in ships for the low pollutant emissions and the high energy efficiency. This paper attempts to investigate the configuration of SOFC system for LNG tanker taking into account the safety and to analyze the influence of design parameters on the system performance. The simulation results provide the basic data for the design and efficiency improvement of SOFC system and indicate the guidelines for the safe system operation.

• Journal of Korea Trade
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• 제26권1호
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• pp.113-125
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• 2022

Purpose - The primary purpose of this study is to verify whether the target set out by the International Maritime Organization (IMO) for reducing carbon emissions from ships can be achieved by quantitatively analyzing the trends in technological advances of fuel oil consumption in the container shipping market. To achieve this purpose, several scenarios are designed considering various options such as eco-friendly fuels, low-speed operation, and the growth in ship size. Design/methodology - The vessel size and speed used in prior studies are utilized to estimate the fuel oil consumption of container ships and the pace of technological progress and Energy Efficiency Design Index (EEDI) regulations are added. A database of 5,260 container ships, as of 2019, is used for multiple linear regression and quantile regression analyses. Findings - The fuel oil consumption of vessels is predominantly affected by their speed, followed by their size, and the annual technological progress is estimated to be 0.57%. As the quantile increases, the influence of ship size and pace of technological progress increases, while the influence of speed and coefficient of EEDI variables decreases. Originality/value - The conservative estimation of carbon emission drawn by a quantitative analysis of the technological progress concerning the fuel efficiency of container vessels shows that it is not possible to achieve IMO targets. Therefore, innovative efforts beyond the current scope of technological progress are required.