• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 학술대회
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• pp.256-261
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• 2008

A CFD analysis of helicopter flowfield in forward flight is considered as non-trivial issue because of the complexity of vorticity-dominated flowfield. In this work, a study on the selection of the proper location for the installation of the Pitot probe is conducted using a CFD code which can deal with the interaction of rotor blade vortex and body. To describe the flow patterns for rotating rotor blades and body, the sliding mesh scheme is utilized. Pressure distributions and flow patterns are also analyzed to identify regions free from the interaction of body and wake induced from rotor blades.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년 추계학술대회논문집
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• pp.256-261
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• 2008

A CFD analysis of helicopter flowfield in forward flight is considered as non-trivial issue because of the complexity of vorticity-dominated flowfield. In this work, a study on the selection of the proper location for the installation of the Pitot probe is conducted using a CFD code which can deal with the interaction of rotor blade vortex and body. To describe the flow patterns for rotating rotor blades and body, the sliding mesh scheme is utilized. Pressure distributions and flow patterns are also analyzed to identify regions free from the interaction of body and wake induced from rotor blades.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 추계학술대회 논문집
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• pp.376-377
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• 2007

In accordance with Madrid and Kyoto Protocols, a 10kW wind turbine installed about 625m away from the King Sejong Station in the Antarctica has been in operation successfully. The current location of the wind turbine has different geographic surroundings from the previous candidate site considered in 2005 and that makes re-evaluation of wind resource at the current site including geographic effects necessary. Especially, strong wind flow derived by steep and complex terrain is dominant in the Antarctica so that computational flow analysis is required. The wind rose measured at the previous and current installation location are identical with strong meteorological correlation but prevailing directions of wind power density are different because of local wind acceleration due to complex terrain. Numerical analysis explains which effects brings this discordance between the two sites, and a design guideline required for additional wind turbine installation has been secured.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 1999년도 학술대회논문집-국제 전기방전 및 플라즈마 심포지엄 Proceedings of 1999 KIIEE Annual Conference-International Symposium of Electrical Discharge and Plasma
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• pp.127-131
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• 1999

In this paper, using a wide-band AE sensor with the frequency range from 100[kHz], the frequency spectra of AE signals generated from the corona discharges of the needle-plane electrode was analyzed to determine the proper ultrasonic sensor. We also examined the relationship between the magnitude of corona discharge and the magnitude of AE signals in peak-to-peak value under the application of 60[Hz] AC high-voltage in oil. From these results, the main frequency spectra of AE signals emitted from the corona discharges of the needle-plane gap were found to be 130[kHz] by the fast fourier transform. The magnitude of AE signals was proportional to the magnitude of corona discharge and discharge current pulse with increasing the applied voltages. Also the detection of corona discharge point location by AE signals was found to be possible by using two sensors.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2013년도 춘계 학술논문 발표대회
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• pp.258-259
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• 2013

Recently, architectural design has been changing from formal design to freeform design due to the digitalization of construction industry. Especially, the formal design has been accepted as a design trend recently and applied many times as a design concept in the architectural design competitions such as turn-key. However, various deflects such as water leak and cracks have been occurred because the traditional construction methods had been applied without any revision or adaptation of the formal construction method for the freeform building construction. Therefore this research proposes location point control method for freeform metal panel installation which is focused on the application of LH JinJu new office.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2009년도 춘계학술대회 논문집
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• pp.352-355
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• 2009

The ground resistance has been used as a method of estimating the capability of counterpoise. When transient currents blow through a ground electrode, it is reasonable to evaluate the performance of ground electrode system as a ground impedance instead of ground resistance. However, the measurement method of ground impedance for counterpoise is not clearly presented. This paper describes the measurement method of ground impedance considering the earth mutual resistances and AC mutual coupling. When we measure the ground impedance, the error due to earth mutual resistances depends on the distance between the auxiliary electrodes and the electrode under test. The measurement accuracy of high frequency ground impedance is mainly influenced by the location of the current electrode and the potential electrode.

• 조명전기설비학회논문지
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• 제18권4호
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• pp.118-123
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• 2004

분산전원의 단독운전 검출에 관한 기존의 연구들은 사고위치에 따른 다양한 상황을 고려하지 않고 조건들만 만족되면 분산전원측을 무조건 분리시켰다. 하지만 분산전원이 연계되어 있지 않은 인근선로사고의 경우에는 인근선로측 보호기기의 동작으로 전원 측으로부터 정상적인 전원이 공급되기 때문에 분산전원을 분리시킬 필요가 없다. 또한 연계선로 사고의 경우일지라도 분산전원이 즉시 분리돼야 하는 경우인지, 단독운전인지, 정상운전의 경우인지 과부하차단에 의한 보호기기 동작의 경우인지를 고려해야 한다. 본 논문에서는 이러한 고려사항들을 계통의 전력상태 변화를 통해 구분하고 단독운전 시 및 분산전원을 분리해야 되는 상황을 찾아서 분산전원을 분리시키는 단독운전 상태 검출 알고리즘을 제안하였다. 고립운전 상태 검출 알고리즘을 검증하기 위하여 PSCAD/EMTDC를 이용하여 사례별로 시뮬레이션을 수행하였다.

• 조명전기설비학회논문지
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• 제17권5호
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• pp.8-14
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• 2003

광센서 조광제어시스템은 실내로 유입되는 주광량에 따라 자동으로 광속량을 조절하여 설정조도를 유지시켜주는 에너지절약 시스템이다. 이 시스템의 성공여부를 결정하는 여러 요인들 중, 광센서의 측광값이 작업면 조도를 얼마나 정확히 나타내는가가 중요한 포인트가 된다. 그래서 본 연구에서는 실험을 통해 광센서의 여러 측광방향 형태를 결정하고, 각 측광방향별 광센서의 반응신호를 측정하였다. 그리고 광센서의 적절한 위치를 찾기 위해 실제공간에서 서로 다른 위치에 광센서를 설치하여, 작업면 조도와 광센서 반응신호의 관계를 측정하고 분석하였다. 분석된 결과를 토대로 광센서의 적절한 위치와 측광방향성을 제시하였다.

• 조명전기설비학회논문지
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• 제26권7호
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• pp.70-76
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• 2012

In general, the unidirectional power flow is normal in distribution feeders before activation of distributed power source such as PV. However, the interactive power flow is likely to occur in case of the power system under distributed generation. This interactive power flow can cause an unexpected effect on convectional protection coordination systems designed based only on the unidirectional power flow system. When the power line system encounters a problem, the interactive power flow can be a contributed current source and this makes the fault current bigger or smaller compared to the unidirectional case. The effect of interactive power flow is varied depending on the location of the point to ground fault, relative location of the PV, and connection method. Therefore it is important to analyse characteristics of fault current and interactive flow for various transformer connection and location of the PV. This paper proposes a method of improved protection coordination which can be adopted in the protective device for customers in distribution feeders interconnected with the PV. The proposed method is simulated and analysed using PSCAD/EMTDC under various conditions.

• 조명전기설비학회논문지
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• 제13권1호
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• pp.21-30
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• 1999

전력용 변압기의 절연 열화를 탐지하기 위한 연구가 오래 전부터 연구되어 왔으며 절연유에 함유된 연소성 가스분석 기술이 주로 활용되고 있다. 최근들어 고압 대용량화에따른 사고 파급효과가 커지게 되면서 on-line 탐지시스템의 필요성이 대두되면서 부분방전 신호 검출법이 연구되기 시작하였다. 본 연구는 부분방전 신호 검출법 중에서 탐촉자의 탈착이 용이한 초음파 신호 측정법에서 가장 큰 문제점인 잡음신호 분리를 위한 연구이다. 신호원의 개수와 위치를 측정할 수 있으므로 측정된 초음파 신호가 부분방전에 의한 것인지 외부 잡음인지를 구별할 수 있으며 변압기의 절연열화 판단에 한층 신뢰성을 향상시킬 수 있게 되었다.