• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1075-1076
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• 2008

이 논문에서는 전류형 MPPT(Maximum Power Point Tracking) 기법을 제안하고 적용하여 태양광 PCS(Power Conditioning System)의 기본적인 제어기를 설계하고 구현하였다. 기본적인 무변압기형 토폴로지에 전류 MPPT를 수행하고 이때에 얻어진 기준전류를 dc/dc 부스트 컨버터를 통해 dc-link에 전압을 충전하여 준다. 이 충전된 파워는 인버터를 통해 계통에 공급되게 된다. 이처럼 크게 MPPT제어, dc/dc컨트롤러, dc-link전류제어, 인버터 전류제어로 나뉘며 본 논문에서는 각 부분의 제어기를 살펴보고 실험을 통해 제어기의 성능을 확인하였다. 실험결과 제안된 전류 MPPT는 원활히 파워를 공급해주었고 dc/dc 부스터 컨버터를 거처 인버터 단까지 파워를 안정적으로 발전하는 것을 확인하였다.

• Journal of Advanced Marine Engineering and Technology
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• v.24 no.5
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• pp.52-57
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• 2000

Recently large capacity of electric equipment and increasing in atomic power generation are shown. One of the reason is shortage of the electric power supply for air conditioning load during summer. And every consumer is concerning about economical refrigeration and air conditioning system to decreases electric power consumption and decrease in global warming. For these necessities, ice making thermal storage system is required. Therefore, in this paper, the possibility of continuous slurry ice making using flowing organic water solution in cooled circular tube has been investigated. The experiments was carried out under some parameters of concentration and velocity of water solution, temperature of cooled tube wall, and control pressure in tube, As a result, four types of operating conditions in the pipe, that was supercooling, continuous ice making, intermittent ice making and ice blockage, were classified . And it was found that the critical condition for continuous ice making was acquired as a function of these experimental parameters.

• Proceedings of the KIPE Conference
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• 2010.07a
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• pp.291-292
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• 2010

The main purpose of this study is to design and develop the grid connected 4kW photovoltatic PCS(Power Conditioning System) targeting for Japanese market. To make this task, the development of DC to DC converter, one phase inverter and EMI filters, and the research on connection between inverter and utility line are made. The developed 4kW PCS has fully carried out performance verifications and evaluation works and acquired the JET(Japan Electrical Safety & Environment Technology Laboratories) certification for safety and performance.

• Journal of Hydrogen and New Energy
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• v.19 no.5
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• pp.417-422
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• 2008

In this paper, a novel DC/DC low-voltage high-current converter circuit is proposed to improve the efficiency of power converter used in the grid-connected fuel-cell generator system. We proposed a novel high efficiency grid-connected power conditioning system for RPG fuel cell. On the result of that, the loss of system was decreased rapidly by driving stack within the condition of maximum efficiency. The peak currents of the current-type inductor and the transformer's coil are reduced by synchronizing switching frequency of Buck-type converter is increased twice as the Push-Pull converter's switching frequency. The novel structure of DC/DC converter is able to realize ZVS-ZCS in fuel-cell system is proposed. The proposed switching component of Push-Pull converter has the ZVS and ZCS function by using the circuit of new passive clamp.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.2
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• pp.183-190
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• 2005

In the process of ice-slurry making, ice adhesion on cooling wall or in narrow flow Path disturbs continuous ice formation. In this study, the effect on the ice adhesion to cooling surface by some freezing experiments was investigated, quantitatively. Three types of solutions were frozen in various coating vessels with stirring. In the experiment, the ice adhesion between cooling wall and Ice-slurry was evaluated by measuring stirring power. From the result, the stirring power of slurry mixture in PTFE-coating vessel was smaller than those in PE-coating, PFA-coating and bare SUS vessel. Especially, in EG H PG 1.S/ HD 1.5 mass$\%$ solution, the stirring power in the PE-coating vessel was smaller than that in the PFA-coating or SUS vessel.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.11 no.1
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• pp.1-9
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• 1999

For roughened annular pipes with diameter ratios of 0.26, 0.39, and 0.56 and with Reynolds numbers ranging 13,000 to 67,000, friction factor, autocorrelation coefficients, power spectral density functions, and integral length scales for each flow condition using X-type hot wire anemometry system are experimentally investigated. Distributions of these quantities show that the times which the streamwise autocorrelation coefficients become zero first increase with decreasing the radius ratios of concentric annuli and Reynolds numbers, however the power spectra density functions increase with increasing the radius ratios and Reynolds number.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.8
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• pp.720-727
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• 2004

In the process of ice-slurry making, the phenomenon of ice adhesion influences extremely to ice making system. In this study, the effect on the ice adhesion by thermal storage material with additives is investigated quantitatively. Various solutions of 300 g in a stainless vessel were frozen under stirring. Through the experiment the ice adhesion between cooling wall and ice-slurry was compared with each other by measuring the stirring power. From the experiment, the stirring power in EG, SCA solution was smaller than those in the solution containing functional materials, such as poly-vinyl-alcohol or kitchen detergent.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.3
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• pp.223-230
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• 2011

The power cycle using ammonia-water mixture as a working fluid is a possible way to improve efficiency of the system of low-temperature source. In this work thermodynamic performance of the ammonia-water regenerative Rankine cycle with partial-boiling flow is analyzed for purpose of extracting maximum power from the source. Effects of the system parameters such as mass fraction of ammonia, turbine inlet pressure or ratio of partial-boiling flow on the system are parametrically investigated. Results show that the power output increases with the mass fraction of ammonia but has a maximum value with respect to the turbine inlet pressure, and is able to reach 22 kW per unit mass flow rate of source air at $180^{\circ}C$.

• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.343-346
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• 2005

In this paper a power conditioning system suitable for the fuel cell powered off-road vehicle is proposed. The proposed system employs a Proton Exchange Membrane Fuel Cell stack combined with boost converter, a super capacitor module combined with hi-directional buck-boost converter, a 4-quadrant DC chopper and a permanent magnet DC motor. The momentary overload condition occurring during the motor starting is handled by the energy stored in the supercapacitor module. Also, the regenerative energy can be stored in the supercapacitor module by operating the system in either buck or boost mode. This capability gives the system designer the higher flexibility in designing the system and assures the lower cost of the system. The validity and feasibility of the proposed system is proven by the computer simulation.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.4 no.3
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• pp.233-241
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• 1992

Temperature distributions in a 3.5 inch hard disk drive including disk surface and internal air have been simulated numerically. Solutions were obtained from fifteen cases regarding three power consumption rates and five ambient conditions. As a result, the velocity of cooling air should be maintained greater than ㏐/s when the power consumption reached 3W in the disk drive. A correlation equation was proposed to predict the temperature field of disk surface and caseing surface.