• 대한전기학회논문지:전력기술부문A
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• 제48권3호
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• pp.330-335
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• 1999

Recently, there a lot of activities on the researches that implement many kinds of control system using power lines. To implement that, it is desirable to use hybrid PSK model because it takes advantage of PSK and DPSK which has a low-bit-error rate. In this parer, we implement the transmitter of this model. Because the power line is not designed for the data communication, we separated the signal generator circuit and the signal loading circuit so that minimized noises from outside. Also, to make it easy on the experiments, most of process are performed by software. As a result, transmitting a high frequency signal on the power line made no effects on the electrical devices.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 C
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• pp.1559-1561
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• 2003

In northeast Asia, there will be several important HVDC transmission lines to be established in Korea and China for perspective electric network market. 5500V 4-inches High voltage thyristor can be used in the DC transmission and distribution of electric power system. In this application, many thyristors are connected in series for each thyristor valves. Therefore, the required low reverse-recovery charge QRR and low on-state voltage drop $V_{TM}$ for such thyristor is necessary to this application. In our work, the on-state and off-state voltage performance was simulated by commercial simulation software.

• Journal of Advanced Marine Engineering and Technology
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• 제35권8호
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• pp.1117-1123
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• 2011

비접지 배전방식이 채택되는 선박은 일선지락 상황에서도 정전사고로 이어지지 않으므로 상대적으로 안정적인 급전이 가능하다. 그러나 비접지 계통에서 발생하는 지락고장은 대지 전압을 왜곡시켜 선체에 대한 선로 전압을 상승시키므로 감전사고와 전기화재의 위험이 높아진다. 특히 선로와 선체 간에 작용하는 분포용량은 대지임피던스의 한 요소로서 지락고장 시 대지전압의 왜곡 특성에 큰 영향을 미친다. 이 같은 대지전압의 변화는 3상 대지전압 중성점의 이동에 의해 설명될 수 있다는 점에서 본 연구에서는 대지임피던스를 입력으로 할 때 대지전압을 출력으로 하는 연산모듈을 구성한 후 이를 이용하여 접지저항 변화에 대응하는 대지전압 중성점의 이동 경로 특성을 확인하였다. 또한 다양한 조건에서 나타나는 중성점 이동경로를 구하는 한편 실제 배전계통에서의 측정 결과와 비교함으로써 제시된 분석방법의 적정성을 나타내었다.

• 소음진동
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• 제7권5호
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• pp.747-756
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• 1997

Wigner-Ville distribution which is a time-frequency analysis has a fatal drawback, when the signal has multiple components. This is the cross-talk and often causes a neagative value in the distribution. Wingner-Ville distriution is an expression of power, therefore the cross-talk must be avoided. Smoothing the Wigner-Ville distribution by convoluting it with a window, is most commonly used to reduce the cross-talk. There can be infinite number of distributions depending on the windows. But, the smoothing reduces resolution in time-frequency plane; this motives to design a more effective window in reducing cross-talk while remaining resolution. The domain in which the cross-talk and legitimate components can be easily distinguished, is the ambiguity function. In the ambiguity function domain, the legitimate components appear as linear lines passing through the orgine. But, the cross-talk is widely distributes in the ambiguity function plane. Based on the relative distributions of cross-talk and legitimate components, rotating window can be designed to minimize cross-talk. Applying the rotating window to the ambiguity function corresponds to smoothing the Wigner-Ville distribution. Therefore, the effects of rotating window is estimated in terms of the bias error due to smooting the Wigner-Ville distribution. By applying the rotating window, not only the Wigner-Ville distribution but also its properties are changed. The properties of the new distribution are checked, in order to complete analyzing the rotating window.

• 조명전기설비학회논문지
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• 제22권6호
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• pp.79-88
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• 2008

본 연구에서는 전력선 근방의 전자파 전자계를 쌍극자 안테나 이론에 의해 도출하였으며 수직 전선배열의 3상전력선 근방의 전자계를 정식화함으로써 전자계 계산을 쉽게 할 수 있도록 하였다. 이 계산식들은 송전선로 및 배전선로의 설계시 전자파 전자계의 검토에 활용할 수 있을 것으로 생각된다. 이와 같이 정식화한 각 전자계 성분요소의 식들을 송전선로 모델에 적용하였으며 매틀랩 프로그램을 작성하여 계산하였다. 이 계산 결과를 요약하면 다음과 같다. 전자계의 x성분 $B_x$ 및 $E_x$는 무시할 수 있을 정도의 작은 값을 나타내며 대지내의 반사파에 의한 영향만을 반영한다. 수평거리 변화에 대하여 $E_y$와 $B_z$의 윤곽이 같으며, $B_y$와 $E_z$의 윤곽도 같다. 이와 같은 사실은 전자파 전계와 자계의 결합요소가 서로 직각으로서 $x{\rightarrow}E_y{\rightarrow}B_z$와 같은 우수계의 전파방향을 갖고 있음을 의미한다. 합성전계 E는 $E_y$요소가 지배적이며 합성자계 B는 $B_z$요소가 지배적이다.

• 전기학회논문지P
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• 제59권4호
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• pp.473-476
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• 2010

In this paper, we analyzed the short circuit current of a low voltage direct current distribution system. For the analysis, we performed the modeling of the low voltage direct current distribution system with a 6-pulse three-phase thyristor rectifier using the PSCAD/EMTDC, surveyed impedance of sources, transformers and distribution lines to run a simulation. A result of the simulation is that short circuit currents of the direct current distribution system with the rectifier decreased due to a thyristor-ON-resistance(Ron). But in case of the low thyristor-ON resistance, output fault current of the rectifier increased over three-phase short circuit current of an AC power system without a rectifier by regular ratio of the rectifier. Because the output fault current of the rectifier can increase over interrupting the capacity of circuit breakers, studying short circuit currents of a low voltage direct current distribution system with a rectifier is necessary for introducing the direct current distribution systems.

• 한국태양에너지학회 논문집
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• 제32권6호
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• pp.76-84
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• 2012

This study conducted experiments to measure air currents in an experimental building according to external conditions, types of induction ducts, and types of internal sockets by applying an external induction duct comprised of inducing openings and lines and induction units to the kitchen and bathroom vents at the rooftop of a super high-rise apartment building in order to help to improve the venting performance. The study also proposed the optimization of the external induction-style kitchen and bathroom vents capable of wind power generation. (1) As for air current distribution according to vent velocity changes, it increased the venting performance of the kitchen and bathroom by 1.0m/s at vent velocity of 2.0m/s or higher and allowed for wind power generation. (2)As for air current distribution according to external velocity changes, it increased the venting performance of the kitchen and bathroom by 1.2m/s at external velocity of 2.0m/s or higher and allowed for wind power generation. (3)As for air current distribution according to wind direction changes($0{\sim}180^{\circ}$), it was favorable for higher vent velocity when the angle between the external induction duct direction and prevailing wind direction was within ${\pm}30^{\circ}$. (4)As for air current distribution according to induction duct type, the[M1] type combining the inducing openings and lines with the induction units recorded the highest improvement effects in the kitchen and bathroom venting performance by increasing vent velocity by 46%. (5)As for air current distribution according to the changing types of internal sockets where the main ducts of the kitchen and bathroom are connected to the external induction ducts, the venturi tube type[Sv] increased vent velocity by 66% based on the smoothest external inflow.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 Techno-Fair 및 추계학술대회 논문집 전기물성,응용부문
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• pp.135-136
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• 2008

In the paper, we evaluated insulation evaluation of EPDM insulator used often in power distribution lines in Korea. The selected samples for our experiment were three EPDM insulators for 22.9[kV] operated for 10 years or less. Using these samples, we observed the discharge pattern through accelerating experimental and analyzed discharge quantity using fractal theory. The validity of our fractal method were discussed and life time. reliability and quantitative analysis of the insulator was conducted through the method.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 추계학술대회 논문집 학회본부 C
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• pp.553-555
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• 2000

Recently polymer insulators are being used for outdoor high voltage applications. Polymer insulators for transmission line have significant advantages over porcelain and glass insulators, especially for ultra-high voltage(UHV) transmission lines. In this paper, the design trend and method polymer insulator are investigated and Aging test method is analysed to know life time of insulator.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 A
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• pp.458-458
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• 2003

In this study the induced-current density distributions in spherical human model by the magnetic field from electric power lines were analysed with visualization and also the effects of phase difference between components of magneto field were investigated.