• Korean Journal of Environment and Ecology
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• v.15 no.3
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• pp.257-266
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• 2001

Trail might be the primary recreational space to appear the use impact by visitors on ecological space in National park. On the basis of this concept, the carrying capacity was estimated on the trail. Impact rating class and pattern of passersby were surveyed on the 22 valid trails in Bukhansan National Park. Using two variables, the width of trail and amount of passersby, the correlation coefficient was analysed and the regression model was derived by raising x to a higher power. And carrying capacity estimation equation was devised by considering the pay fee visitors and average passersby in a trail section. With carrying capacity estimation equation to apply Bukansan National Park, it is desired that maximum carrying capacity is about 3 million persons a year under conditions of trail width 2.2m when National Park Authority wants to keep the existing management level. If they strengthen the management goal far resource conservation like that they want to keep the trail width 2.0m, the number of visitors might be decreased to about 2 million persons a year.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.9 no.4
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• pp.78-85
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• 1995

This paper covers stability and stabilization of Multi-Excited Induction Motor used in numberous electric equipment system of industrial field. The induction motor with multi-excitation has tow sets of three-phase system : One is connected to the AC source to supply most power required at the load, and the other is to the inverter for variable frequency and/or magnitude of voltage. The conventional induction motor is operated under single excitation mode only, that is called induction mode. But in multi-excited induction motor both the induction mode and the synchronous mode are possible, and the proposed multi-excited induction motor can be driven as a synchronous motor by the extra three-phase input. At the synchronous mode the efficiency is improved so higher than that at induction mode or conventional induction motor. The rating of the inverter used for speed control of numberous electric equipment system can be reduced upto one-tenth of that for conventional induction motor. Also the cost and maintenance fee of multi-excited induction motor can be reduced compared to any other motor.

• Proceedings of the KIEE Conference
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• 2006.04b
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• pp.362-364
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• 2006

This paper presents a novel DC-DC Converter for 3 [kW] Fuel Cell System Residential Application. Phase shifted control is employed to regulate the output voltage and achieve soft switching. The transformer leakage inductance is utilized effectively to achieve zero voltage turn on for the power semiconductor switches. The current doubler rectifier has only one diode drop. The transformer secondary winding current rating is one half the load current. The overall effciency of the converter is improved.

• Proceedings of the KIEE Conference
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• 2008.04c
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• pp.50-52
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• 2008

In this paper, we investigated the iron losses in the rotor core of interior permanent magnet synchronous machine (IPMSM), which have distributed armature windings. From the analysis results, we can conclude that iron losses of rotor are definitely large at load condition if the number of slots per pole is fractional. Since the slot-pole combination may induce excessive heating, particular care should be necessary in design of PMSM for a high power rating application such as electric vehicles.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.379-381
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• 1996

본 논문에서는 그리드 독립형 태양광 풍력 복합 발전 시스템에 대한 최적의 태양광 어레이 사이즈 및 풍력 발전 시스템을 결정하는 방법을 제안하였다. 연구에 사용되어진 풍력 및 태양광 일사량에 대한 데이터는 제주도 지역에서 1년간 실측되어진 데이터를 기준으로 하였으며, 이러한 실측되어진 데이터는 풍속 및 태양광의 확률 밀도 함수(Probability Density Function)를 결정하는데 사용되어 졌다. 풍속 및 태양광 일사량의 확률 밀도 함수와 태양광 어레이 및 풍력 발전기의 여러 파라미터는 복합 발전 시스템의 평균 발생 전력을 계산하는데 사용하였고, 도서지역에서 1년간 계측되어진 부하의 변동에 대하여 최적의 태양광 어레이, 풍력 발전 용량을 선정 하기 위하여 최적 자승의 법칙이 사용되었다.

• Proceedings of the KIPE Conference
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• 2003.07a
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• pp.36-39
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• 2003

The push pull forward converter is a very suitable circuit for low output voltage, high output current applications with a wide input voltage range. All the magnetic components (output inductor, transformer, input filter) can be integrated into a single core. The integrated magnetics can reduce the number of the magnetic components. Developed the push pull forward converter rating are of 36 $\~$72V input and 3.3V/30A output. In this converter, the efficiency was measured by $76.4\%$ at full load and 82.95$\%$ at full load. The maximum efficiency is up to 83.$\%$ at 200kHz switching frequency, l1A output.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.8 no.2
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• pp.35-43
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• 1999

The paper describes an approach for measuring delivery flow ripple generated by oil hydraulic axial piston pumps. In order to reduce pressure ripple which cause to undesirable noise. vibration and fatigue in hydraulic systems it is indispensible measure a delivery flow ripple from pumps. Since the flow ripple measurement of flow pumps is independent of the dynamic characteristics of the connected hydraulic circuit the measurement of flow ripple is most suitable for pump fluid-borne noise rating. The measurement of flow ripple with high frequencies from axial piston pumps is made by applying the remote instantaneous flow rate measurement method which is based on the dynamic characteristics between pressure and flow rate in hydraulic pipeline. The measured flow ripple waveforms are influenced by the configuration of V-shaped triangular relief groove in the valve plate. It can be seen that the appropriate relief groove in valve plate reduces the pressure and flow ripple amplitude and frequency spectrum for high harmonics.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2004.11a
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• pp.115-120
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• 2004

Most of the LV customer have been applied the distribution system of 3-phase four wire system because of its advantage of supplying both of 1-phase & 3-phase loads simultaneously. Due to its structural simplicity, it is more convenient for use rather than the conventional separated scheme. But uneven load distribution or unclean voltage quality has occurred various problems such as do-rating, losses increase and vibration, etc. In this paper, voltage, current and power waveform in the actual fields have measured and analyzed in relation with internationally allowable voltage unbalance limits and compared the current unbalance factor with the load unbalance factor.

• Proceedings of the KIPE Conference
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• 2017.11a
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• pp.11-12
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• 2017

본 논문에서는 전기자동차 800V/14V LDC용 낮은 전압정격을 갖는 소프트 스위칭 컨버터를 제안한다. 제안하는 컨버터는 입력이 직렬구조로써 입력전압의 절반으로 낮은 스위치의 전압정격을 갖기 때문에 도통손실과 스위칭 손실 저감 효과를 갖고, 넓은 입력전압 및 부하영역에서 소프트 스위칭을 성취하여 높은 효율을 달성할 수 있으며 변압기의 직렬연결로 된 커패시터로 인해 자화전류의 오프셋이 없다. 제안하는 소프트 스위칭 컨버터의 동작원리를 제시하고 시작품을 통해 본 논문의 타당성을 검증하였다.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.59 no.1
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• pp.18-23
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• 2010

As the increasing of Non-linear load, we have been growing interest for the harmonics. Harmonics has been focused on the current component rather than voltages. Voltage harmonics can be mainly generated at the PCC with non-linear load and act on voltage unbalance. Voltage harmonics can be enlarged at the capacitor with low impedance as frequency increases. Capacitor is basically used for the power-factor compensation and sometimes as the passive filter. Small voltage of low-order acts on quite a few at the capacitor by the current increase. Capacitor has easily fall under by harmonic components. In this paper, we measured the magnitude and phase angle of asymmetrical voltage with harmonics components at the PCC and calculated with the same condition. we concluded that voltage harmonics of higher order increase each current component but have a little effect on capacitor rating.