• New & Renewable Energy
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• v.1 no.4 s.4
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• pp.49-54
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• 2005

There is close relation between the heat generation in the fuel cell stack and the fuel performance. In PEM fuel cell vehicles, the stack coolant temperature is about $65^{\circ}C$, which is far lower than that for general automobile engine. Therefore, it is hard to release heat generated in the stack by using a radiator of limited size because of the reduced temperature difference between the coolant and the ambient air. In this study, indirect stack cooling system using $CO_2$ heat pump was designed and its stack cooling performance in releasing heat to the ambient was investigated. This work focuses on a series of processes that grasp the relation among the fuel cell power, the radiator capacity and the stack temperature. The purpose of this work is to find out a way to properly release sufficient amount of heat through the finite sized radiator, so that the slack power generation can not be deteriorated due to the stack temperature increase. The optimization between the compressor power consumption and the fuel cell output power can be carried out to maximize the performance of fuel cell system.

• Journal of KIBIM
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• v.9 no.3
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• pp.19-29
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• 2019

Currently, BIPV (Building Integrated Photovoltaic) design technology lacks analysis function at the planning stage, and there is a lack of understanding and reliability of BIPV design method and system for building designers. To design and consider various building integrated solar design alternatives, the color of building integrated solar is often monotonous or does not match the design direction of the building. In this study, architectural designers can select various color modules in the planning and design process of the building and analyze the characteristics of color module solar cells and compare and analyze the actual solar radiation and predicted solar radiation in Republic ofKorea Seoul to reduce the confusion of design methods. By building a BIM design integrated system that can prove the quality of the building and analyze the shading analysis and power generation performance architecturally, it can improve the reliability of color module solar cell applicability that can express aesthetics in buildings and the predicted solar power generation capacity of each region. In the initial design stage, based on the empirical data of the BIPV system, it is possible to analyze the power generation performance for each installation angle and installation direction by analyzing the surrounding environment and the installation area, and accurately determine the appropriateness of the design accordingly.

• Smart Structures and Systems
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• v.22 no.1
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• pp.81-94
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• 2018

Automatic Generation Control (AGC) has functionally controlled the interchange power flow in order to suppress the dynamic oscillations of frequency and tie-line power deviations as a perturbation occurs in the interconnected multi-area power system. Furthermore, Flexible AC Transmission Systems (FACTS) can effectively assist AGC to more enhance the dynamic stability of power system. So, Static Synchronous Series Compensator (SSSC), one of the well-known FACTS devices, is here applied to accurately control and regulate the load frequency of multi-area multi-source interconnected power system. The research and efforts made in this regard have caused to introduce the Fractional Order Proportional Integral Derivative (FOPID) based SSSC, to alleviate both the most significant issues in multi-area interconnected power systems i.e., frequency and tie-line power deviations. Due to multi-objective nature of aforementioned problem, suppression of the frequency and tie-line power deviations is formularized in the form of a multi-object problem. Considering the high performance of Multi Objective Bees Algorithm (MOBA) in solution of the non-linear objectives, it has been utilized to appropriately unravel the optimization problem. To verify and validate the dynamic performance of self-defined FOPID-SSSC, it has been thoroughly evaluated in three different multi-area interconnected power systems. Meanwhile, the dynamic performance of FOPID-SSSC has been accurately compared with a conventional controller based SSSC while the power systems are affected by different Step Load Perturbations (SLPs). Eventually, the simulation results of all three power systems have transparently demonstrated the dynamic performance of FOPID-SSSC to significantly suppress the frequency and tie-line power deviations as compared to conventional controller based SSSC.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.43 no.2
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• pp.1-13
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• 2020

There are several methods of peak-shaving, which reduces grid power demand, electricity bought from electricity utility, through lowering "demand spike" during On-Peak period. An optimization method using linear programming is proposed, which can be used to perform peak-shaving of grid power demand for grid-connected PV+ system. Proposed peak shaving method is based on the forecast data for electricity load and photovoltaic power generation. Results from proposed method are compared with those from On-Off and Real Time methods which do not need forecast data. The results also compared to those from ideal case, an optimization method which use measured data for forecast data, that is, error-free forecast data. To see the effects of forecast error 36 error scenarios are developed, which consider error types of forecast, nMAE (normalizes Mean Absolute Error) for photovoltaic power forecast and MAPE (Mean Absolute Percentage Error) for load demand forecast. And the effects of forecast error are investigated including critical error scenarios which provide worse results compared to those of other scenarios. It is shown that proposed peak shaving method are much better than On-Off and Real Time methods under almost all the scenario of forecast error. And it is also shown that the results from our method are not so bad compared to the ideal case using error-free forecast.

• Proceedings of the KIEE Conference
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• 2000.07a
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• pp.354-356
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• 2000

This paper describes the strategy of a daily optimal operational scheduling on cogeneration systems with each other generation mode. The cogeneration systems consists of three generators. auxiiiary devices which are three auxiliary boilers, two waste boilers and three sludge incinerators. One unit that using the back pressure turbin generates the electrical and the thermal energy. The other two units that using the extraction condensing turbine generate the energy. Auxiliary devices operate to supplement the thermal energy to the thermal load with three units. The cogeneration system has a large capacity which is able to supply enough the thermal energy to the thermal load, however the electric power generated is insufficient to satisfy the electrical load. Therefore the insufficient electric energy is supplemented by buying electrical energy from the utility. Simulation was carried out using optimization toolbox. The result reveals that the proposed modeling and strategy can be effectively applied to cogeneration systems with each other generation mode.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.43 no.5
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• pp.739-746
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• 1994

This paper present an efficient methodology to solve the unit commitment problem for large scaled power system which involves various type of generation. We introduce the global optimization approach to coordinate the thermal type, hydro type and pumped storage type generation. To overcome the shortcomings in dynamic programming for thermal unit commitment, an improved heurisitic method using lambda(λ) was proposed, Hydro and pumped type allocation was Solved by analytical approach using λ which exculde undisirable iteration for satisfying the energy usage constraints. The case studies for proposed algorithm are proven by sample system and KEPCO practical system, which produced very resonable both computing requirements and convergency.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.51-54
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• 2005

Generator efficiency optimization is important for economic saving and environmental pollution reduction. In general, the machine loss can be reduced by the decreasing the flux level, resulting in the significant reduction of the core loss. This paper proposesan model-based controller is used to decrement the excitation current component on the basis of measured stator current and machine parameters and the q-axis current component controls the generator torque, by which the speed of the induction generator iscontrolled according to the variation of the wind speed in order to produce the maximum output power. The generator reference speed is adjusted according to the optimum tip-speed ratio. The generated power flows into the utility grid through the back-to-back PWM converter. The grid-side converter controls the dc link voltage and the line-side power factor by the q-axis and the d-axis current control, respectively. Experimental results are shown to verify the validity of the proposed scheme.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.5
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• pp.591-595
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• 2013

This paper presents a method of generation rescheduling using Newton's Approach which searches the solution of the Lagrangian function. The generation fuel cost and $CO_2$ emission cost functions are used as objective function to reallocate power generation while satisfying several equality and inequality constraints. The Pareto optimum in the fuel cost and emission objectives has a number of non-dominated solutions. The economic effects are analyzed under several different conditions, and $CO_2$ emission reductions offered by the use of storage are considered. The proposed approach can explore more efficient and noninferior solutions of a Multiobjective optimization problem. The method proposed is applied to a 4-machine 6-buses system to demonstrate its effectiveness.

• The Journal of the Korea institute of electronic communication sciences
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• v.18 no.1
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• pp.45-52
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• 2023

The power generation method using expensive diesel has operation problems such as high cost diesel generator and a lack of reserved power due to increase of power demand in some islands, requiring expansion of power generation facilities. To solve this problems, it is necessary to improve the efficiency of power generation facilities through an ORC(Organic Rankin Cycle) system application that uses waste heat as a heat source. Therefore, localized application technology of price competitive and highly reliable ORC power generation system is needed, and optimization technology of generators is having great effect, so this study performed two generator designs to get a high-efficiency generator with an optimized 30kW output. The comparison of simulation data for two designed models showed that a generator with SPM factor of 46.2% had an efficiency of 92.1% and a power ouput of about 23.2kW based on 12,000rpm, a generator with SPM factor of 44.46%, had a power output of 27.9kW and efficiency of 93.6% based on above rpm. For the verification of improved design model with SPM factor of 44.46%, the prototype test system with 110kW motor dynamometer was installed and got to the efficiency of 92.08% with conditions of the rated capacity 25kW at 12,000rpm, the test results of prototype generator showed the validity of generator design.

• Journal of Advanced Marine Engineering and Technology
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• v.36 no.5
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• pp.595-602
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• 2012

In this study, for the purpose of reduction of $CO_2$ gas emission and to increase recovery of waste heat from ships, the ORC (Organic Rankine Cycle) is investigated and offered for the conversion of temperature heat to electricity from waste heat energy from ships. Simulation was performed with waste heat from the exhaust gasse which is relatively high temperature and cooling sea water which is relatively low temperature from ships. Various fluid is used for simulation of the ORC system with variable temperature and flow condition and efficiency of system and output power is compared. Finally, 2,400kW output power is obtained by system optimization of the preheater and reheater utilizing waste heat form sea water cooling system.