• Journal of Environmental Science International
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• v.27 no.7
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• pp.555-560
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• 2018

This study conducted to analyze the growth characteristics of old Prunus yedoensis on Jeju island. The diameter growth per year was measured using a DTRS-2000 instrument. The DBH, ground DBH and height of the investigated P. yedoensis were 137 cm, 143 cm, and 15.5 m, respectively. Our analysis showed that the age of the old P. yedoensis was 93 years. An annual diameter growth of $2.85mm{\pm}0.96$ was observed. The result of age estimation, about $265{\pm}64$ years in P. yedoensis on Jeju island. This information could be useful to understand the annual diameter growth characteristics the P. yedoensis distributed on Jeju island.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.55 no.1
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• pp.9-15
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• 2006

The conventional hysterysis band DTC(Direct Torque Control) strategy have relatively high torque ripple at low speed and variable switching frequency according to motor speed even though it provides a fast torque response with very simple scheme consisted with only two hysteresis band comparators and a switching table for torque and flux control. In this paper, author proposed a new DTC scheme based on the torque slope and reference voltage control. The new scheme can maintain the minimized torque ripple and constant switching frequency. Experimental tests carried out with an 1.5kW induction motor drive system show improved dynamic characteristics and prove the feasibility of proposed strategy.

• Proceedings of the KIPE Conference
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• 2007.07a
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• pp.64-66
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• 2007

Photovoltaic power systems convert sunlight directly into electricity. A residential PV power system enables a homeowner to generate some or all of their daily electrical energy demand on their own roof, exchanging daytime excess power for future energy needs In this paper, It was suggested that new design method for PV system installation for the purpose of system efficiency improvement. and according to loss parameter compensation method, designed for the PV system and investigated through the simulation practically.

• Proceedings of the KIPE Conference
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• 2007.07a
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• pp.69-70
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• 2007

This paper presents experimental operation with utility interactive 50kw photovoltaic generation system. And that describe configuration of utility interactive photovoltaic system which power supply for dormitory. The status of photovoltaic generation system components and interconnection and safety equipment will be summarized. This paper try analyzing the operating characteristic according to secular variation of a 50kw photovoltaic system.

• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.1135-1137
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• 2003

The conventional DTC strategy provides a fast torque response even though it has very simple scheme consisted with only two hysteresis band comparators and a switching table for torque and flux control. Drawbacks of the conventional BTC are relatively high torque ripple at low speed and variation of the switching frequency according to motor speed. In this paper, the new direct torque control(BTC) schemes are proposed. Those schemes are based on the torque slope and and flux to reduce the torque ripple.

• Proceedings of the KIEE Conference
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• 2009.04b
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• pp.240-241
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• 2009

본 논문에서는 다양한 아치형 태양광발전(Photovoltaic : PV) 시스템을 시뮬레이션을 통하여 구성하고 그 운전특성을 최적의 경사각을 가지는 일정 경사각 PV 시스템과 비교 분석하였다. 결과 아치형 PV 시스템의 경우 모두 PV 어레이 경사각이 $30^{\circ}$인 일정 경사형 시스템에 비하여 9% 이상의 큰 차이가 남을 알 수 있었으며, 최적의 아치경사각은 $10^{\circ}\sim30^{\circ}$임을 알 수 있었다.

• Proceedings of the KIPE Conference
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• 2008.10a
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• pp.212-214
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• 2008

태양광발전시스템은 태양전지 모듈, PCS 등의 구성요소의 성능평가 뿐만 아니라 일사강도 및 온도 등의 환경변화에 따라 발전성능이 결정된다. 따라서 실제 운전시 태양광발전시스템 및 구성요소기기의 성능개선, 시스템의 설계시공 및 사후운영관리의 유용성을 위해 설계에 따른 시뮬레이션을 통한 성능특성과 주요 손실에 대한 평가분석이 필요하다. 본 논문에서는 30kW급 계통연계형 태양광발전시스템의 설계에 따른 시뮬레이션을 통하여 시스템의 성능특성과 주요 손실에 대하여 평가분석 하고자 한다.

• Proceedings of the KIEE Conference
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• 2005.10c
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• pp.229-231
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• 2005

A sensorless control scheme for the switched reluctance motor (SRM) drive at speed control is presented in this paper. In this paper proposes a very simple method to estimate the rotor position of a switched reluctance motor. By on-line estimating the self-inductance of the motor, the rotor position of the SR motor is obtained, and a closed-loop drive system can be achieved. Proposed methods can easy implement to application with sensorless SR motor drive system. SR motor simulation executed with self inductance estimation and result represented.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1441-1443
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• 2005

In this paper proposes a very simple method to estimate the rotor position of a switched reluctance motor. By on-line estimating the self-inductance of the motor, the rotor position of the SR motor is obtained, and a closed-loop drive system can be achieved. Proposed methods can easy implement to application with sensorless SR motor drive system. SR motor simulation executed with self inductance estimation and result represented. Simulation result verified the rotor position using the proposed self-inductance estimation method.

• Proceedings of the KIEE Conference
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• 1995.07a
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• pp.350-352
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• 1995

The starting characteristics of single phase induction motor(SPIM) is described by control of phase and voltage. Auxiliary winding voltage is controlled by DC amplifier and phase is integrator. These processes enable comparison of torque with slip in each voltage and phase angle variations. Simulation and experimentation results of the motor's torque-slip characteristics using the controlled auxiliary winding voltage and phase angle arc shown and discussed. As a results, starting time is fast and main winding current is small when auxiliary winding voltage is low than rating voltage and starting characteristics is good in phase angle $90^{\circ}$.