• 한국물환경학회지
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• 제26권3호
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• pp.532-539
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• 2010

The synthetic unit hydrograph is developed and verified using Nash model and characteristic velocities considering geomorphological dispersion in this present study. Application watersheds are selected 5 subwatersheds of Bocheong basin. The mean and variance of hillslope and stream path length are estimated in each watershed with GIS. Characteristic velocities are calculated using estimated path lengths and moment characteristics of rainfall-runoff data. Characteristic velocities of random devised 7 ungauged watersheds are estimated through regional analysis of chracteristic velocities in guaged watershed. And Nash model parameters and IUH are derived using characteristic velocities and path length in the gauged and ungauged watershed. The result to compare of IUH about gauged watershed and random devised ungauged watershed in application watershed presents coherently hydrologic response characteristics that peak discharge is reduced and peak time is extended. In conclusion, Developed synthetic unit hydrograph in this study expects that it is useful method to estimate runoff discharge for managing of water pollution in ungauged watershed.

• 한국전기전자재료학회논문지
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• 제25권9호
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• pp.727-731
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• 2012

This paper dealt with the measurement and analysis of electromagnetic waves radiated from a partial discharge (PD) source in insulation oil to apply condition monitoring of oil-immersed transformers. Two types of narrow-band monopole antennas with the resonant frequency of a 500 MHz and a 1 GHz were designed and fabricated. Also, a needle-plane electrode system was manufactured to simulate PDs and the curvature radius of the needle is 10 ${\mu}m$ and the diameter of the plane is 60 mm. Electromagnetic wave was measured by the PD measurement system with the monopole antennas. Detection sensitivity of the fabricated antenna was compared for the same PD magnitude; 620 $mV_{peak}$ for the 500 MHz antenna and 960 $mV_{peak}$ for the 1 GHz antenna to the PD magnitude of 74 pC. Consequently, the 1 GHz monopole antenna is more effective to detect PDs in oil-immersed transformers.

• Journal of Power Electronics
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• 제16권3호
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• pp.1218-1225
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• 2016

The avionic battery discharge regulator (BDR) plays an important role in a power-conditioning unit. With its merits of high efficiency, stable transfer function, and continuous input and output currents, the non-isolated Weinberg converter (NIWC) is suitable for avionic BDR. An improved peak current control strategy is proposed to achieve high current-sharing accuracy. Current and voltage regulators are designed based on a small signal model of a three-module NIWC system. The system with the designed regulators operates stably under any condition and achieves excellent transient response and current-sharing accuracy.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 추계학술대회 논문집 학회본부
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• pp.200-202
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• 1996

MgO film was deposited on the glass substrate by the hollow cathode discharge ion plating method and the characteristics of the MgO thin film such as deposition rate, crystalline orientation, surface morphology and secondary electron coefficient were investigated. The deposition rate of MgO thin films were $430^{\sim}1270{\AA}$/min at various temperatures and biases. The crystalline orientation of the MgO thin film changed from (200) to (220) upon increasing the HCD current from 100A to 200A. These results indicated that the crystallin orientation of the MgO thin film was determined by the super-saturation ratio. The (200) peak decreased and the (220) peak increased as the substrate bias increased, while both peaks increased as the substrate temperature increased. The grain size increased as the substrate bias increased and the secondary electron emission coefficient increased as the substrate bias increased.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2016년도 학술발표회
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• pp.164-164
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• 2016

Radar rainfall estimates have been widely used in calculating rainfall amount approximately and predicting flood risks. The radar rainfall estimates have a number of error sources such as beam blockage and ground clutter hinder their applications to hydrological flood forecasting. Moreover, it has been reported in paper that those errors are inter-correlated spatially and temporally. Therefore, in the current study, we tested influence about spatio-temporal errors in radar rainfall estimates. Spatio-temporal errors were simulated through a stochastic simulation model, called Multivariate Autoregressive (MAR). For runoff simulation, the Nam River basin in South Korea was used with the distributed rainfall-runoff model, Vflo. The results indicated that spatio-temporal dependent errors caused much higher variations in peak discharge than spatial dependent errors. To further investigate the effect of the magnitude of time correlation among radar errors, different magnitudes of temporal correlations were employed during the rainfall-runoff simulation. The results indicated that strong correlation caused a higher variation in peak discharge. This concluded that the effects on reducing temporal and spatial correlation must be taken in addition to correcting the biases in radar rainfall estimates. Acknowledgements This research was supported by a grant from a Strategic Research Project (Development of Flood Warning and Snowfall Estimation Platform Using Hydrological Radars), which was funded by the Korea Institute of Construction Technology.

• The Korean Journal of Physiology
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• 제28권2호
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• pp.133-141
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• 1994

The discharge patterns and peripheral nerve inputs to cardiovascular neurons were investigated in rostral ventrolateral medulla (RVLM) and raphe nucleus of cats. The data from the two were compared to determine their roles in cardiovascular regulation and the endogenous analgesic system. Animals were anesthetized with ${\alpha}-chloralose$ and single cell activities were recorded by carbon-filament microelectrode and their relationships with cardiovascular activity were analyzed. In RVLM area, a total of thirty-three cells were identified as cardiovascular neurons. During one cardiac cycle, the mean discharge rate of the neurons was $1.96{\pm}0.29$ and the peak activity was observed 45 ms after the systolic peak of arterial blood pressure. Thirteen cells could be activated antidromically by stimulation of the the $T_2$ intermediolateral nucleus. Forty-three raphe neurons were identified as cardiovascular neurons whose mean discharge rate during one cardiac cycle was $1.02{\pm}0.12$. None of these cells could be activated antidromically. Study of the interval time histogram of RVLM neurons revealed that the time to the first peak was $128{\pm}20.0\;ms$, being shorter than the period of a cardiac cycle. The same parameter found from the raphe neurons was $481{\pm}67.2\;ms$, which was much longer than the cardiac cycle length. Of seventeen RVLM neurons examined ten received only the peripheral $A{\delta}-afferent$ inputs, whereas six RVLM neurons received both $A{\delta}-$ and C-inputs; the remaining one cell received an inhibitory peripheral C-input. In contrast, nine of eleven raphe neurons were found to receive $A{\delta}-inputs$ only. We conclude that the main output of cardiovascular regulatory influences are mediated through the RVLM neurons. The cardiovascular neurons in the raphe nucleus appear to serve as interneurons transferring cardiovascular afferent information to the raphespinal neurons mediating the endogenous analgesic mechanisms.

• 한국전기전자재료학회논문지
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• 제11권11호
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• pp.1043-1048
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• 1998

The decomposition performance of the Surface induced Plasma Chemical Processing(SPCP) for benzene, toluene, xylene and $NO_2$ were experimentally examined. Discharge exciting frequency range was 5kHz and 10kHz, and low frequency discharge requires high voltage to inject high electric power in gas and to decompose contaminants. The decomposition rate of dioxide nitrogen for 5kHz power in gas and to decompose contaminants. The decomposition rate of dioxide nitrogen for 5kHz power supply is only 85%, but it’s rate for 10kHz power supply is very high, more than 96% when peak voltage is 12kv. Aromatic hydrocarbon vapor of up to 1000ppm is almost throughly decomposed at the flow rate of 1000$\ell$/min or lower rate under the discharge with electric power of several hundred watts. High decomposition rate is shown in every case, that is, for SPCP reactor is necessary to obtain the decomposition rate of more than 80~98%. The decomposition rate of benzene, toluene and xylene were 90~98% and dioxide nitrogen was 45~96%.

• Spatial Information Research
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• 제15권2호
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• pp.159-167
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• 2007

본 연구에서는 현재 홍수설계에 적용되고 있는 Huff 방법이 집중호우사상에까지 확장 적용될 가능성이 있는지를 확인하고자 하였다. 이를 위해 2006년 7월 집중강우가 발생한 평창 오대천 유역을 중심으로 집중강우에 의한 실측 강우량과 이를 Huff방법에 의해 설계 강우량으로 환산하고 유출량을 산출하고 또한 홍수위로 환산하여 흔적수위와 비교하였다. 비교 결과 설계강우에 의해 산출된 홍수량은 실제 발생했던 실제 집중강우를 적용하였을 경우의 첨두홍수량에 비해 1/2정도에 불과한 작은 값을 보였다. 또한 실제 집중호우에 의해 발생한 홍수량은 단시간에 발생한 강우사상임에도 불구하고 적용대상유역의 150년 빈도 홍수량에 근접하는 것으로 나타났다.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2005년도 추계종합학술대회
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• pp.208-211
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• 2005

This paper presents an ultra-low partial discharge(PD) measurement system that has been accepted as a non-destructive method to estimate electrical insulation of low-voltage electric devices. The PD measurement system is composed of a coupling network, a low noise amplifier, and associated electronics. A shielding box is used to make a better condition against electromagnetic interference. A low cut-off frequency of the coupling network was 1MHz(-3 dB). Calibration tests on laboratory set-up have shown that the PD measurement system has a stable sensitivity of 11.4mV/pC. In an application experiment on a low-voltage induction motor(5HP), we could detect 0.77pC level of partial discharge pulse at the applied voltage of AC 664 V$_{peak}$.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 C
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• pp.1828-1830
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• 2003

Partial discharge(PD) tests are used to evaluate the insulation condition of stator windings in two 4.16kV and three 6.6kV motors. These tests were conducted using a conventional partial discharge detector(PDD) and turbine generator analyzer(TGA). Off-line PD measurements were performed on five high voltage motors. PD magnitudes ranged from 1000 pC to 5400 pC at the normal line-to-ground voltage. Five high voltage motors have been equipped with 80pF epoxy-mica coupler on the motor terminal box. The PD pulse from sensors were measured with the TGA instrument. TGA summarizes each plot with two Quantities such as the peak PD magnitude(Qm) and the total PD activity(NQN). The defect mechanisms of high voltage motor can be associated with PD patterns such as internal, slot and conductor surface discharges. The PDD and TGA test results of No. 4 motor showed that internal discharge was detected in voids of the groundwall insulation.