• 한국전기전자재료학회논문지
• /
• 제11권12호
• /
• pp.1055-1059
• /
• 1998

The correlation between the propagation of electrical tree and distributions of partial discharge(PD) pulses accompanying with electrical tree of bush type in low density polyethylene were discussed. We measured the growth of electrical tree by using optical microscope and PD data simultaneously. The PD data detected and analyzed were PD magnitude, repetition rate, average discharge power, average phase angle, and $\psi$-q-n distribution pattern. The average discharge power and repetition rate of PD had good linear relation with area of tree. Repetition rate and peak discharge magnitude and width of discharge phase angle increased with the tree.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 1987년도 한국자동제어학술회의논문집; 한국과학기술대학, 충남; 16-17 Oct. 1987
• /
• pp.680-683
• /
• 1987

The speech signal processing in the auditory system can be analysized based on two representations : Average discharge rate and Temporal discharge pattern. But the average discharge rate representation is restricted by the narrow dynamic range because of the rate saturation and the two tone suppression phenomena, and the temporal discharge pattern representation needs a sophisticate frequency analysis and synchrony measure. In this paper, a simple representation is proposed : using a model considering the interaction of Cochlear fluid-BM movement and a haircell model, the feature of speech signals (formant frequency and pitch of vowels) is easily estimated in the Average Synchronized Rate.

• 한국안전학회지
• /
• 제15권1호
• /
• pp.100-105
• /
• 2000

Correlation between propagation of bush-type electrical tree and internal partial discharges(PD) was discussed. We used specimens with needle-plane electrode system made of LDPE(Low Density Polyethylene), observed inception and propagation of electrical tree by optical microscope interfaced with computer and investigated characteristics of phase resolved PD pulses accompanying with propagation of electrical tree. Electrical tree generally growed bush-type tree. PD data detected and analyzed were average discharge current and statistical operator of q-n, $\psi$- $q_{avg}$, $\psi$-n, ${\psi}-q_{max}$ distribution. Parameters used were skewness, kurtosis, average discharge phase, cross-correlation factor, asymmetry and etc. In generally, average discharge current had good linear relationship with propagation of bush type electrical tree on this experiment. Peak discharge magnitude and repetition rate were increased, but they had not good linear relationship.p.

• 한국산림과학회지
• /
• 제107권2호
• /
• pp.158-165
• /
• 2018

산지하천의 평균유속을 정확하게 추정하는 것은 하천의 수리적 흐름을 이해하고, 사방댐과 같은 사방구조물 최적 설계를 위해 중요하다. 산지하천의 평균 유속에 대한 연구는 부족한 실정이나 최근에는 상대적으로 자료 확보가 용이한 유량 자료를 이용하여 유량과 평균유속의 관계를 파악하는 연구들이 많이 진행되고 있다. 이 연구에서는 8개소의 서로 다른 산지소하천에서 조사된 87회의 유량과 평균 유속 자료를 분석하였다. 산지하천의 유량과 평균유속을 측정하기 위해 salt-dilution 방법을 사용하였으며, 평균유속은 도달 시간의 조화 평균을 적용하여 구하였다. 하천의 거칠기 높이를 이용하여 유량과 유속과의 무차원 관계식을 도출하였다. 거칠기 높이는 하상재료의 $D_{50}$, $D_{84}$와 하상변위의 ${\sigma}_{pro}$, $IPR_{90}$를 이용하였으며, ${\sigma}_{pro}$와 $IPR_{90}$의 정확성이 더 높게 나타났다. 일반적으로 유량과 평균 유속은 지수함수 관계를 보였다.

• 한국컴퓨터산업학회논문지
• /
• 제4권12호
• /
• pp.1013-1020
• /
• 2003

본 논문에서는 소형변압기에 적용되는 절연재료의 전기적 신뢰성을 평가하기 위하여 시간변화에 따른 방전전하량 특성을 조사하였다. 10[kV]의 교류전압을 인가한 후 $\pm$5[V]의 전압으로 변환시켜 A/D변환기를 통해 컴퓨터로 데이터를 저장하였으며 인가된 파형의 한주기 및 방전전하량 값을 64개로 분할하고 10초 동안 발생한 전하량을 위상별로 누적하였다. 이 값들을 분석한 결과, 전압인가시간이 증가함에 따라 방전발생빈도수 및 총 방전전하량은 감소하였으며 평균 방전전하량의 변화폭이 완만해짐을 알 수 있었다.

• 한국전기전자재료학회논문지
• /
• 제20권9호
• /
• pp.780-786
• /
• 2007

This paper describes the influence on partial discharge characteristics of defects at the model XLPE/EPDM interfaces of power cable joints. The defects of void and copper which could inadvertently be present at the joint interface. We measured ${\Phi}-n,\;{\Phi}-q$ patterns by a computer-aided partial discharge measuring system. Several parameters i, e, maximum discharge $q_{max}$ [pC], average discharge q [pC/cycle], and average angle of discharge ${\Theta}g$ [deg] were found to depend upon the defect type varying applied voltage. As the result of time evaluation, partial discharges are small different at copper defects, but is decreasing obviously about 20 minutes at void defect. It considered that difference of magnitude of total positive discharge of Q+ [pC] and total negative discharge of Q- [pC] is SPMD(swarming pulsive micro discharges).

• 상하수도학회지
• /
• 제19권5호
• /
• pp.619-624
• /
• 2005

This work is for examining a simplified equation based on the rational formula, which can easily decide storm-water detention volume in small urban catchments. The storm-water detention volume is determined by the inflow hydrograph flowing to detention basin and the outflow hydrograph discharged from the detention basin. The ratio of average outflow over the period of rainfall duration against allowable discharge was 0.5 in former simplified equation. But this research has found that the average outflow ratio depends on the storage methodology. In the case of the on-line storage method, the average outflow ratio is a function of the time of concentration of the catchments and rainfall duration, which ranged from 0.5~1.0. In the case of the off-line storage method, the average ratio is a function of peak discharge and allowable discharge except above time of concentration and rainfall duration, where its function value ranged from 1.0~2.0. When applying this equation to small catchment in Mokpo city, South Korea, we could easily calculate the relation curve between the storm-water detention volume and allowable discharge.

• 대한전기학회논문지
• /
• 제45권3호
• /
• pp.432-437
• /
• 1996

This paper describes a diagnostic technique of power transformers by on-line detection of ultrasonic signals. A trend of partial discharge variation in a real transformer was estimated by counting the number of ultrasonic signals until insulation paper in the point-to-plane electrode is punctured. The number of electrical signals is closely related to the ultrasonic signals generated by partial discharge. The trend of the ultrasonic signal number could easily be distinguished by taking moving average. The insulation failure due to partial discharge in transformers can be predicted based on the trend analysis of ultrasonic signal number caused by partial discharge. (author). 14 refs., 10 figs.

• 한국환경과학회지
• /
• 제26권9호
• /
• pp.999-1011
• /
• 2017

In this study, the Chiu-2D velocity-flow rate distribution based on theoretical background of the entropy probability method was applied to actual ADCP measurement data of Gangjung Stream in Jeju from July 2011 to June 2015 to predict the parameter that take part in velocity distribution of the stream. In addition, surface velocity measured by SIV (Surface Image Velocimeter) was applied to the predicted parameter to calculate discharge. Calculated discharge was compared with observed discharge of ADCP observed during the same time to analyze propriety and applicability of depth of water velocity average conversion factor. To check applicability of the predicted stream parameter, surface velocity and discharge were calculated using SIV and compared with velocity and flow based on ADCP. Discharge calculated by applying velocity factor of SIV to the Chiu-2D velocity-flow rate distribution and discharge based on depth of water velocity average conversion factor of 0.85 were $0.7171m^3/sec$ and $0.5758m^3/sec$, respectively. Their error rates compared to average ADCP discharge of $0.6664m^3/sec$ were respectively 7.63% and 13.64%. Discharge based on the Chiu-2D velocity-flow distribution showed lower error rate compared to discharge based on depth of water velocity average conversion factor of 0.85.

• KIEE International Transactions on Electrophysics and Applications
• /
• 제2C권6호
• /
• pp.297-303
• /
• 2002

We have developed an on-line ultrasonic detector to monitor partial discharge in an operating transformer. The ultrasonic sensor has 150[KHz] resonance frequency and contains a pre-amplifier with 60[㏈] gain. The on-line ultrasonic detector has 50~300[KHz] frequency band-pass filter to remove electrical and mechanical noises from the transformer. This detector has an ultrasonic signal discrimination algorithm which discriminates ultrasonic signals due to partial discharge in a transformer. A moving average method of ultrasonic signal number was employed to effectively monitor the increasing trend of the partial discharge. This paper describes an experience of partial discharge detection in a 154[㎸] operating transformer using an ultrasonic detector. With regards to gas analysis in oil, C2H2 gas was produced with a warning level in this transformer We detected ultrasonic signals on the transformer steel wall, and estimated the position of partial discharge. With further inspection, we found carbonized marks due to partial discharge on the supporting bolt which fastens the windings.