• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 학술대회 논문집 전문대학교육위원
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• pp.52-54
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• 2002

A resonant type voltage source and power device and a control method using Pulse Density Modulation(PDM) power control and Pulse Width Modulation(PWM) voltage control for plasma sterilization are described, For the stability of discharge in the generating tube, it is desirable that the peak apply voltage is constant. The PDM power control is employed for sustaining the voltage constant at any generating tube input power. Moreover, to avoid the influence of input AC voltage fluctuation etc.. PWM voltage control with generating tube peak voltage feedback is used. Both functions were confirmed by the experiment with 6.5[kHz], 1.8[kW] inverter and generating tube. The effect of input synchronous PDM method for input current stabilizing is confirmed also.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 B
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• pp.1172-1174
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• 2003

A resonant type voltage source and power device and a control method using Pulse Density Modulation(PDM) power control and Pulse Width Modulation(PWM)voltage control for plasma sterilization are described. For the stability of discharge in the generating tube, it is desirable that the peak apply voltage is constant. The PDM power control is employed for sustaining the voltage constant at any generating tube input power. Moreover, to avoid the influence of input AC voltage fluctuation etc., PWM voltage control with generating tube peak voltage feedback is used. Both functions were confirmed by the experiment with inverter and generating tube. The effect of input synchronous PDM method for input current stabilizing is confirmed also.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2003년도 학술대회논문집
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• pp.397-401
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• 2003

A resonant type voltage source and power device and a control method using Pulse Density Modulation(PDM) power control and Pulse Width Modulation(PWM) voltage control for plasma sterilization are described. For the stability of discharge in the generating tube, it is desirable that the peak apply voltage is constant The PDM power control is employed for sustaining the voltage constant at any generating tube input power. Moreover, to avoid the influence of input AC voltage fluctuation etc., PWM voltage control with generating tube peak voltage feedback is used. Both functions were confirmed by the experiment with 6.5[㎑], 1.8[㎾] inverter and generating tube. The effect of input synchronous PDM method for input current stabilizing is confirmed also.

• 대한원격탐사학회지
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• 제5권1호
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• pp.13-27
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• 1989

In recent years satellite data have been increasingly used for the analysis of floodprone areas. This study was carried out to demonstrate the usefulness of repetitive satellite imagery in monitoring flood levels of the Pyungchang watershed. Runoff characteristics parameters were analyzed by Soil Conservation Service(SCS) Runoff Curve Number(RCN) based on Landsat imagery and Digital Terrain Model data. The RCN average within the watershed was calculated from RCN estimates for all the pixels(picture elements) and adjusted by antecedent precipitation conditions. The direct runoff hydrograph was derived from the unit hydrograph using SCS dimensionless unit hydrograph and effective rainfalls estimated by the SCS method. In comparsion of the direct runoff hydrograph with the measured rating curve their peak times differ by one hour and peak discharges differ by 5.9 percents of the discharge from each other. It was shown that repetitive satellite image could be very useful in timely estimating watershed runoffs and evaluating ever-changing surface conditions of a river basin.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2015년도 학술발표회
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• pp.180-180
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• 2015

Weather radar has been widely used in measuring precipitation and discharge and predicting flood risks. The radar rainfall estimate has one of the essential problems in terms of uncertainty and accuracy. Previous study analyzed radar errors to reduce its uncertainty or to improve its accuracy. Furthermore, a recent analyzed the effect of radar error on rainfall-runoff using spatial error model (SEM). SEM appropriately reproduced radar error including spatial correlation. Since the SEM does not take the time dependence into account, its time variability was not properly investigated. Therefore, in the current study, we extend the SEM including time dependence as well as spatial dependence, named after Spatial-Temporal Error Model (STEM). Radar rainfall events generated with STEM were tested so that the peak runoff from the response of a basin could be investigated according to dependent error. The Nam River basin, South Korea, was employed to illustrate the effects of STEM on runoff peak flow.

• 한국환경과학회지
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• 제28권2호
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• pp.211-217
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• 2019

A Numerical modeling approach is usually applied to reproduce the physical phenomena of a fill dam-break. The accuracy of the dam-break model depends on the physical structure that defines input variables such as the storage volume, breach formation and progress, and the parameters of the model, which are subjective as they are prescribed by users. In this study, a sensitivity analysis was performed for the nonlinear breach progression curve that was already developed, which includes four parameters. The study focuses on the two of the parameters which control the breach forming time and peak discharge. The model is coupled with a two-dimensional flood simulation model (FLO-2D) to examine flood coverage and depth. It is generally observed that the parameter ${\beta}$ controls only the breach forming time, the parameter ${\gamma}$ is particularly sensitive to the peak flow.

• 한국수자원학회논문집
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• 제33권6호
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• pp.701-709
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• 2000

통합저류함수모형을 IHP 대표유역인 위천과 보청천유역 그리고 대유역인 남한강유역과 낙동강유역의 강우-유출사상에 적용하여 모형의 타당성을 검토하였다. 제안된 모형에 의한 예측 결과와 관측치를 비교해 볼 때 전체적인 수문곡선의 재현성 및 첨두홍수량의 예측에 있어서 상당히 우수한 결과를 나타내었다. 그러나 첨두홍수 발생시간에서는 퍼지제어의 효과로 인해 다소 오차가 발생하였다. 또한 상류단 유입량이 잔유역 유입량에 비하여 상당히 큰 경우에는 충분한 예보선행시간을 확보하기 어려운 문제점이 나타났다.

• Journal of Magnetics
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• 제20권3호
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• pp.312-316
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• 2015

Unlike conventional Eddy Current Test (ECT), Pulsed Eddy Current (PEC) uses a multiple-frequency current pulse through the excitation coil. In the present study, the detection of subsurface cracks using a specially designed probe that allows the detection of a deeper crack with a relatively small current density has been attempted using the PEC technique. The tested sample is a piece of 304 stainless steel (SS304) with a thickness of 30mm. Small electrical discharge machining (EDM) notches were put in the test sample at different depths from the surface to simulate the subsurface cracks in a pipe. The designed PEC probe consists of an excitation coil and a Hall sensor and can detect a subsurface crack as narrow and shallow as 0.2 mm wide and 2 mm deep. The maximum distance between the probe and the defect is 28 mm. The peak amplitude of the detected pulse is used to evaluate the cracks under the sample surface. In time domain analysis, the greater the crack depth the greater the peak amplitude of the detected pulse. The experimental results indicated that the proposed system has the potential to detect the subsurface cracks in stainless steel plates.

• 한국진공학회지
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• 제7권4호
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• pp.410-414
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• 1998

본 연구에서는 플라즈마 중합 반응의 기판 재질과 전극 위치에 대한 의존성을 규명 하기 위해서 Ar방전의 발광 분석을 행하였으며 제작된 박막의 가교성을 확인하기 위해서 전자빔 노광을 시켜보았다. 기판의 재질이 도체 및 절연체인 양자의 경우를 비교해 보면 전 자는 후자에 비해서 전체적으로 발광 스펙트럼의 피이크 강도가 크게 나타났으며, 준안정상 태에 대한 피이크와 이온에 대한 피이크를 검토한 결과, 기판이 절연물일 때는 전극의 위치 를 멀게 할수록 이온의 피이크 강도가 극단까지 떨어짐을 알 수 있었다. 제작된 중합스티렌 박막을 통하여 발광 스펙트럼의 변화에 따라서 막의 가교성 변화가 생기는 것을 알 수 있었 으며 이 막을 전자빔에 노광하였을 때, 기판이 절연물인 경우에는 패턴을 제작하는 것이 가 능하였다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 하계종합학술대회 논문집(5)
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• pp.319-322
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• 2002

In this Paper, we suggested the Half-Bridge inverter for the automotive HID electronic ballast. electronic ballast for automotive HID lamp should be supplied by low-frequency square wave avoiding the acoustic resonance(11kHz ∼ 825kHz). When the HID lamp is hot state, the electronic ballast should supply the sufficient current for a few milli-second to the lamp at the re-strike ignition state. that is called take-over current. We have introduced the new take-over current control method that could have reduced the peak current and supplied the sufficient take-over current.