• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2000년도 제1회 학술대회 논문집
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• pp.21-22
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• 2000

Laser diagnostic method in a plasma display discharge cell was introduced. The information of electric field, potential and electron temperature et al. in the surface of plasma display panel can be measured using laser induced fluorescence spectroscopy. However, because of the very small discharge dimension of ${\sim}$ 100 ${\mu}m$, the measurement attempt has almost not been performed. In this paper, the direct measurement possibility of the parameters and the recent work of electric field measurement are demonstrated in the plasma display panel.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 E
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• pp.1663-1665
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• 1997

Direct measurements of electric fields in a glow discharge are difficult because the measurement method should be sensitive to the electric field and non-intrusive. Laser spectroscopy is very suitable in that it is non-intrusive and allow in-situ measurements to be made. In this report, the measurement techniques of electric fields in glow discharge using laser spectroscopy were described.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2012년도 춘계학술발표회 논문집
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• pp.336-337
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• 2012

본 연구에서는 HMDS (400sccm)/$O_2$(20slm)/He(5slm)/Ar(10slm)의 가스를 사용하여 remote-type discharge와 direct-type discharge로 구성된 double discharge system을 이용하여 SiOx 박막을 증착시켰다. 특히, 본 연구는 frequency의 변화가 SiOx 박막의 특성과 plasma특성에 어떠한 영향을 미치는지 조사하였다.

• 한국농공학회지
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• 제32권3호
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• pp.87-101
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• 1990

The purpose of this study is to estimate the flood discharge and runoff volume at a stream by using geomorphologic parameters obtained from the topographic maps following the law of stream classification and ordering by Horton and Strahier. The present model is modified from Cheng' s model which derives the geomorphologic instantaneous unit hydrograph. The present model uses the results of Laplace transformation and convolution intergral of probability density function of the travel time at each state. The stream flow velocity parameters are determined as a function of the rainfall intensity, and the effective rainfall is calculated by the SCS method. The total direct runoff volume until the time to peak is estimated by assuming a triangular hydrograph. The model is used to estimate the time to peak, the flood discharge, and the direct runoff at Andong, Imha. Geomchon, and Sunsan basin in the Nakdong River system. The results of the model application are as follows : 1.For each basin, as the rainfall intensity doubles form 1 mm/h to 2 mm/h with the same rainfall duration of 1 hour, the hydrographs show that the runoff volume doubles while the duration of the base flow and the time to peak are the same. This aggrees with the theory of the unit hydrograph. 2.Comparisions of the model predicted and observed values show that small relative errors of 0.44-7.4% of the flood discharge, and 1 hour difference in time to peak except the Geomchon basin which shows 10.32% and 2 hours respectively. 3.When the rainfall intensity is small, the error of flood discharge estimated by using this model is relatively large. The reason of this might be because of introducing the flood velocity concept in the stream flow velocity. 4.Total direct runoff volume until the time to peak estimated by using this model has small relative error comparing with the observed data. 5.The sensitivity analysis of velocity parameters to flood discharge shows that the flood discharge is sensitive to the velocity coefficient while it is insensitive to the ratio of arrival time of moving portion to that of storage portion of a stream and to the ratio of arrival time of stream to that of overland flow.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 C
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• pp.1846-1849
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• 2000

Off-line and on-line partial discharges were measured on a 828MVA, 22kV and direct hydrogen-cooled large turbine generator. Partial discharge tests were conducted using digital partial discharge detector(PDD) and turbine generator analyzer(TGA). PDD and TGA showed that off-line partial discharge pattern seems to be very, similar to that found with on-line. Most of the partial discharge is originating with the stator slot in the three phases. As the partial discharge activity is very low, the stator insulation condition of this generator is very good.

• Environmental Engineering Research
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• 제10권3호
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• pp.144-154
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• 2005

The use of ozone gained acceptance in the production of ultrapure water because of its powerful oxidizing ability. Ozone is currently used to deactivate microorganisms and remove organic contaminants. However, interest also exists in using radical species, which arc stronger oxidants than ozone, in such processes. One means of producing radical species is by corona discharge. This work investigates the use of a novel pulseless corona-discharge system for the removal of organic substances in ultrapure water production. The method combines corona discharge with electrohydrodynamic spraying of oxygen, forming microbubbles. Experimental results show that pulseless corona discharge effectively removes organics, such as phenol and methylene blue, in deionized water. The corona-discharge method is demonstrated to be comparable to the direct use of ozone at a high-applied voltage. The results also show that a minimum applied voltage exists for operation of the corona-discharge method. In this work, the minimum applied voltage is approximately 4.5 kV. The kinetic rate or phenol degradation in the reactor is modeled. Modeling results show that the dominant species of the pulseless corona-discharge reactor are hydroxyl radical and aqueous electron. Several radical species produced in the pulseless corona-discharge process are identified experimentally. The. major species are hydroxyl radical, atomic hydrogen species, and ozone.

• 대한기계학회논문집
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• 제1권2호
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• pp.65-72
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• 1977

Major problems in the design and use of refief valve are (a) chattering because of instability, (b) excessive pressure differential which makes the valves crack far below maximum pressure diminishing useful flow in the system. In this study, A magnet-coupled relief valve is investigated theoretically and experimentally in order to improve the performance of a conventional direct type reliefvalve. A theory is developed to predict the performance, response, and stability of the magnet-coupled valve taking into account the delivery line response. In the experiment, a typical magnet-coupled relief valve is designed on the basis of the analytical results; the discharge rates are measured varying the supply pressure, and both the pressure-time curves and valve displacament-time curves are recorded providing the supply pressures greater than the setting pressure. The measured override characteristic curves are then compared with those of conventional pilot type and direct type releif valves. It is showm that the excessive pressure differential of a magnet-coupled relief valve becomes less than that of a conventional direct type valve. It is also shown that the most important chatacteristic of a magnet-coupled relief valve is to eliminate valve chattering due to instability regardless of the magnitude of setting pressures and discharge rates, which suggests wide applications of the idea of the use of a magnet in the design of hydraulic valves.

• Journal of Electrical Engineering and Technology
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• 제13권6호
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• pp.2421-2424
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• 2018

A direct measurement of an initiation carrier injection for a low voltage discharge is presented. A self-sustained pulsed discharge is utilized to characterize electrical responses of a glow discharge for varying amounts of injected initiation carriers. It is clearly demonstrated that the initiation carrier injection affects the ignition time and the breakdown voltage of the primary discharge. An abrupt reduction in the breakdown voltage for a $300{\mu}m$ gap pin-plate discharge is observed when a threshold carrier density of $3{\times}10^{11}cm^{-3}$ is injected and the breakdown voltage continues to decrease to 250 V with increasing the initiation carrier injection beyond the threshold density.

• 한국수자원학회논문집
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• 제34권5호
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• pp.551-560
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• 2001

낙동강의 화원-교령교-현풍 수위관측소 구간에 대하여 수리학적 하도추적을 통하여 조도계수를 추정하였다. 세 관측소의 연속 수위자료와 하천 종횡단 측량자료만이 이에 사용되었다. 하도추적에 의해 계산된 유량자료로부터 수위-유량 관계식을 작성하였으며 이는 기존의 수위-유량 관계식보다 나은 결과를 보였다. 수위측정 오차가 유량계산에 미치는 영향에 대하여 분석하였으며, 측방유입류를 억제할 수 있도록 하도길이를 제한하는 방법도 제시하였다.

• Korean Journal of Hydrosciences
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• 제7권
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• pp.107-124
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• 1996

Pipe design normally requires pump power, discharge or pipe diameter for each condition given. Due to several investigators the pipe friction factor con now be estimated by explicit way for a wide range of flow condition. In various problems of pipe design, however, the flow condition cannot be pre-determined even for a uniformly rough pipe. In these cases a lot of iterations are often required to have an accurate solution with ordinary approach. This paper presents the direct computation method of discharge and pipe diameter without any iteration process. Introducing the power law of friction factor, various non-dimensional physical numbers are derived such as power-diameter number, power-discharge number, diameter-slope number and discharge-slope number. One of the physical numbers concerned with discharge or pipe diameter can be related to a combination of the other in an explicit way.