• The Transactions of the Korean Institute of Power Electronics
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• v.4 no.3
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• pp.304-309
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• 1999

In this paper, a new 24longleftarrowpulse diode rectifier system based upon the conventional series-connected 12-pulse rectifier is p proposed with the least number of switching devices and low VA rating of the additional passive components. The p proposed approach does not employ any active switching devices. Therefore, the system is rugged and simple to i implement. Detailed analysis with VA rating calculation of the components is presented and experimental results from a a 220V, 3kV A rectifier system verify the proposed concept.

• Progress in Superconductivity and Cryogenics
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• v.4 no.1
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• pp.61-65
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• 2002

It becomes difficult and high in cost to construct new ducts and/or tunnels for power cables in metropolitan areas. This paper presents possible applications of an HTS superconducting power cables for transmitting electric power in metropolitan areas. Reflected were its important distinction such as compactness for installation in underground ducts and considerably high efficiency compared with present underground cables. In this paper, system modeling, transmission capacity and voltage class of compact HTS cables which should be applied to existing ducts were reviewed. Based on this, the following items on urban transmission system are examined. (1) A method of constructing a model system to introduce high temperature superconducting cables to metropolitan areas is presented. (2)The maximum outer diameter of HTS cables to be accommodated in exiting ducts is calculated based on the design standards for current cable ducts. (3)The voltage level that can be accommodated by existing ducts is examined.

• Journal of Electrical Engineering and Technology
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• v.9 no.1
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• pp.205-213
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• 2014

A wind generator (WG) maximum power point tracking (MPPT) system is presented here. It comprises of a variable-speed wind generator, a high-efficiency boost-type dc/dc converter and a control unit. The advantages of the aimed system are that it does not call for the knowledge of the wind speed or the optimal power characteristics and that it operates at a variable speed, thus providing high efficiency. The WG operates at variable speed and thus suffers lower stress on the shafts and gears compared to constant-speed systems. It results in a better exploitation of the available wind energy, especially in the low wind-speed range of 2.5-4.5 m/s. It does not depend on the WG wind and rotor-speed ratings or the dc/dc converter power rating. Higher reliability, lower complexity and cost, and less mechanical stress of the WG. It can be applied to battery-charging applications.

• Journal of Power Electronics
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• v.8 no.1
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• pp.51-59
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• 2008

This paper addresses several issues concerning the analysis, design, modeling, simulation and development of single-phase, single-switch, power factor corrected AC-DC high frequency switching converter topologies with transformer isolation. A detailed analysis and design is presented for single-switch topologies, namely forward buck, flyback, Cuk, Sepic and Zeta buck-boost converters, with high frequency isolation for discontinuous conduction modes (DCM) of operation. With an awareness of modem design trends towards improved performance, these switching converters are designed for low power rating and low output voltage, typically 20.25W with 13.5V in DCM operation. Laboratory prototypes of the proposed single-switch converters in DCM operation are developed and test results are presented to validate the proposed design and developed model of the system.

• Proceedings of the KIPE Conference
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• 2009.11a
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• pp.228-230
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• 2009

본 논문에서는 전류형 인버터(CSI)와 전압형 인버터(VSI)를 조합하여 유도성 부하에 정현파 전류를 공급하는 시스템에서, LC 소자를 추가함으로써 전압형 인버터의 VA rating을 줄일 수 있는 방법을 제안하였다. 전력제어용 스위칭 소자인 SCR은 대용량인 장점이 있는 반면에 턴오프 제어가 되지 않고, 비선형 특성으로 인해 고조파가 발생한다. 이러한 단점을 개선하기 위해 전압형 인버터를 사용하여, SCR를 OFF하고 부하에 정현파 전압/전류를 제공한다. 또한, 출력단에 수동 LC 필터를 추가하여 전압원 인버터의 VA rating을 저감시키는 구조를 연구하고 이를 Psim을 이용한 시뮬레이션을 통해 검증하였다.

• Journal of the Korean Institute of Landscape Architecture
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• v.26 no.2
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• pp.91-100
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• 1998

This paper is to study on rating system of some shrubs for pedestrian control with concentrate upon the density of branch. It was usd that Hibiscus syricacus L., Spiraea prunifolia var. simpliciflora Nak, Ligustrum obtusifolium S. et Z., Callicarpa dichotoma Raeusch., Rhoododendron mucrionulatum Turcz., Syringa vulgaris L., Weigela subsessilis L. H. Bailey, Cercis chinensis bunge, Forsythia koreana Nak., Euonymus alatus Sieb, Chaenomeles speciosa Nak., orbaria sorbifolia var. stellipila Max., Deutzia parviflora Bunge, Kerria japonica De Candolle, Prunus tomentosa Thunberg ex Murray, Purunus grandulosa for. albiplena Koehne. Shrubs are invesitgated ito the density of branch, the power of sprout, height, a rate of growth, hardness of naturalizaton, crown width and existence of thorns. Shrubs belonged to high group of rating system for pedestrian control were Euonymus alatus Sieb, Purunus grandulosa for. albiplena Koehne, Chaenomeles speciosa Nak., Spiraea prunifolia var. simpliciflora Nak., Prunus tomentosa Thunberg ex Murray, Rhododendron mucronulatum Turcz., Hibiscus syricacus L., Ligustrum obtusifolium S. et Z., Syringa vulgaris L., Weigela subsessilis L.H.Bailey.

• Journal of Power Electronics
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• v.1 no.1
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• pp.19-25
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• 2001

A high speed, three phase, 12/8 pole, 225 kW switched reluctance motor (SRM) has been designed and analyzed. A circuital approach has been used to find the geometry, windings parameters and electromagnetic loading. Then, the 3D finite element method (FEM) has been used to calculate the static torque more accurately and optimize the design. The efficiency of the designed SRM is almost constant over wide range of speed and its phase current is less sensitive to the speed than that of an induction motor of the same rating. Recommendations for manufacturers and users are given.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.1050-1052
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• 2000

An investigation into power conditioners that interface with photovoltaic array and utilities has been completed. The rating for this investigation is residential system (3-5kW) that interface with a 220V single phase utility connection. As the result of this investigation. a 3kW high frequency PWM IGBT inverter feeding a high frequency isolation transformer with a sinusoidal current wave was selected. The output of the transformer rectified with a diode bridge rectifier four IGBT, used as 60Hz switched, reverse the polarity of the rectified current on every other half cycle of the utility voltage. Even though the high frequency link system used more power semiconductors, a net size, weight, and parts cost saving result compared to the other systems due to elimination of 60Hz transformer.

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.46-49
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• 2001

An investigation into power conditioners that interface with photovoltaic array and utilities has been completed. The rating for this investigation is residential system(3-5kVA) that interface with a 220V single phase utility connection. As the result of this investigation, a 3kVA high frequency PWM IGBT inverter feeding a high frequency isolation transformer with a sinusoidal current wave was selected. The output of the transformer rectified with a diode bridge rectifier. four IGBT, used as 60Hz switched, reverse the polarity of the rectified current on every other half cycle of the utility voltage. Even though the high frequency link system used more power semiconductors, a net size, weight, and parts cost saving result compared to the other systems due to elimination of 60Hz transformer.

• The Transactions of the Korean Institute of Power Electronics
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• v.9 no.4
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• pp.326-333
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• 2004

This research proposes a high frequency resonant inverter for high power conversion apparatus, which is consist of two L-C linked full-bridge inverter using MOSFET in order to distribute voltage and current of the devices. As an output power control strategy, the time sharing control method is applied. From the computer simulation results, the inverters and devices can be shared properly voltage and current rating of the system. And also, theoretical characteristics of the proposed circuit are compared with experimental results.