• 물과 미래
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• 제15권3호
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• pp.49-55
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• 1982

본 연구는 중소하천유역에 있어서 미국토양보존전국(U.S. Soil conservation Service)의 SCS 방법과 $\Phi$-Index 방법과를 비교하면서 유효우량을 산정하고 또한 설계수문곡선의 첨두유량을 산정하는데 목적을 두고 있다. 낙동강 유역에 속한 신천유역은 UNESCO의 주관아래 국제수문 개발계획 대표시험유역으로 채택되었던 유역으로서 그 중요성이 크다고 생각하여 SCS 방법의 적용을 위하여 균양군의 분류에 따른 토지이용 및 처리 상태와 토양의 분류, 토양의 종류 등을 파악하여 유출수를 구하였다. 그리고 주요호우의 총우량일유효우량관계 자료에 의한 평균유출수와 비교해 본 결과 SCS 방법의 유출수가 적게 나타났으며, 신천유역의 5개 측소의 강우자료로부터 $\Phi$-Index 법에 의한 유효우량과도 비교하였다. 한편 설계수문곡선의 첨두유량은 SCS법, Chow법, Mockus법과 비교해 본 결과, SCS법의 무차원수문곡선과 Chow법이 실측에 의한 단위도의 첨두유량과 가까운 적합성을 보여주었다.

• 한국전자파학회논문지
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• 제28권8호
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• pp.646-652
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• 2017

큰 부피의 플라즈마를 발생시키기 위하여 플라즈마 층을 포함하는 유전체 장벽 방전 구조(dielectric barrier discharge)를 제안하고, 발생기 동작 유무에 따른 모노스태틱 레이다 단면적(mono-static radar cross section)을 측정함으로써 대기압 플라즈마가 전자기파에 미치는 영향을 분석하였다. 다수의 전극을 평면으로 평행 배열함으로써 플라즈마 층의 부피를 증가시켰으며, 전극 배열과 수직인 방향의 전기장을 포함하는 전자기파를 입사시킴으로써 발생기와의 원치 않는 커플링을 최소화 시켰다. 실험 결과, 모노스태틱 레이다 단면적을 2 GHz부터 25 GHz까지 측정하였을 때, K band에서 최대 8 dB까지 감소하는 것을 확인하였다. 또한, 고전압 발생기의 인가 전압을 최대 20 kV까지 변화시킴으로써 원하는 주파수에서 플라즈마로 인한 감소치를 유연하게 조절 가능함을 보였다.

• 한국수자원학회논문집
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• 제38권6호
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• pp.485-494
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• 2005

유량과 수질의 관계를 분석하는 것은 매우 중요하다. 하천의 실시간적 관리를 위해서는 유량과 수질의 측정이 동일한 지점에서 동시간적으로 이루어져야 보다 효과적이다. 그러나 수질자동측정망 지점과 T/M 수위관측소가 원거리에 위치한 경우들이 있으며, 평창강 수질자동측정망 지점이 그 중 하나이다. 이러한 지점에서는 보다 정확한 유량 산정과 이를 활용한 예측 프로그램이나 시스템이 요구된다. 이번 연구에서는 미계측 지점인 평창강 수질자동측정망 지점에 유량예측 신경망 모형을 적용하고, 적용성을 검토하기 위해 WMS 모형의 모의결과와 비교하였다. WMS 모형은 첨두유량이 작고, 수문곡선이 단조로운 사상에 적합한 것으로 나타났다. 신경망 모형의 유출량 예측값은 비유량과 WMS 모형의 모의값에 근사하였으며, 미계측 지점에서의 유출량 변화성향을 잘 반영하는 것으로 나타났다.

• 환경영향평가
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• 제11권4호
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• pp.271-280
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• 2002

The purpose of this study is to explore the hydrological impacts and soil loss variation due to the land use change of Namak New Town development area. The analysis of hydrological effects and soil loss variation has been carried out using GIS in this study. In order to estimate the peak runoff volume, the Rational Method which is the most popular technique to predict runoff amounts is used. To estimate the soil loss in the study area, Universal Soil Loss Equation(USLE), which is one of the most comprehensive and useful technique to predict soil erosion is adopted. The result of this study has shown that the peak runoff volume and the total soil loss increase according to the land use change. The peak runoff volume and the total soil loss have been increased about 2 times and about 48 times more than that of pre development. The increasing of the peak runoff volume can be effective erosion, flooding and so on. A careful city planning is the first essential step to minimize the environmental impacts and to construct the ecological city.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제49권12호
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• pp.665-672
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• 2000

This paper described the measurement technology to analyze the partial discharge characteristics for long term aging of insulations. This system was consisted of high voltage generation and measurement part, PD detection part, digital conversion and signal processing part. We used the VXI system for digital conversion and signal processing part. In the digital conversion part, we studied the error of partial discharge magnitude and memory capacity for reading digital signal with the sampling rate. In the signal processing part, we showed the program algorithm to count pulses and read peak values of partial discharge. The allowable minimum sampling rate of digizer was decided to 250kS/s through analyzing test. We confirmed that this system was very useful in the study of $\phi-q-n$ characteristics of long term PD experiments with specimens being consisted of internal void defects and CIGRE II electrodes.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1997년도 춘계학술대회 논문집
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• pp.172-176
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• 1997

It is likely that the corona discharge appears due to the motion and the multiplication of electron and ion under the nonuniform electric field. Because the motion and the multiplication of electron and ion are the function of electric field, for the simulation of the corona discharge, we have to calculate the electric field, before the calculation of the motion and the multiplication of electron and ion. In this paper, the electric field is calculated on the assumption that the gap between a hyperboloidal needle and a plane is 1-dimension, and the motion and the multiplication of electron and ion are determined by Flux-Corrected Transport method. For this purpose, we solve the electron and ion continuity equation together with Poisson equation. We calculated the current density and the electron and ion density distributions between electrodes as well as electric field distortion due to the space charge assuming that the discharge channel radius is 100${\mu}{\textrm}{m}$. In this simulation, it is found that the current density has one peak as observed by experiment, and electric field distortion is important to the formation and the stability of the corona discharge.

• 한국재료학회지
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• 제12권6호
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• pp.447-451
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• 2002

Pulsed DC-plasma nitriding has been applied to form nitride layer having only a diffusion layer. The discharge current with the variation of discharge gases is proportional to the intensity of $N_2^+$ peak in optical emission spectroscopy during the plasma nitriding. The discharge current, microhardness in surface of substrate and depth of nitride layer increased with the ratio of $N_2\;to\;H_2$ gas in discharge gases. When the ratio of $N_2\;to\;H_2$ is lower than 60% in the discharge gases, high microhardness value of 1100Hv nitride layer which contains no compound layer has been formed.

• 한국생산제조학회지
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• 제20권6호
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• pp.714-719
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• 2011

The surface roughness depending on the machining method is very important because is produce a finished product through riveting, sealing, bonding, and special paint in order to curb the turbulence and air resistance which occur between the sheets. Aluminum alloy 2024 which is widely used for interior and exterior material of aircraft are tested. Jin-young JW-60C wire cutting machine was used in this experiment. In this paper, the experimental investigation has been performed to find out the influence of the surface roughness and surface shape characteristics on the wire-cut EDM of discharge energy in aluminium alloy 2024. The selected experimental parameters are peak current, no-load voltage, off time and feed rate. The experimental results give the guideline for selecting reasonable machining parameters. The high discharge energy on the idle time, almost no change in surface roughness can be seen.

• 한국환경과학회지
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• 제14권4호
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• pp.405-412
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• 2005

Groundwater in Jeju Island, flowing through main stream, is spring water from underground. To set a fixed quantity of groundwater flowing from surface in a hydrological view, 4 downstream (Woedo stream, Gangjung stream, Yeonwoe stream and Ongpo stream) were selected to calculate the characteristic of baseflow and the base-flow discharge through the data on tachometry. There were 11 to 14 level peak caused by runoff, mostly occurred during monsoon season. Also, duration of runoff was 15 to 25 hours, well reflecting the characteristic of inclined, short stream length in Jeju Island and pervious hydrogeographical feature. In case of Gangjung stream, Yeonwoe stream and Ongpo stream, variation of stream water level by baseflow rose above during summer, which was closely linked to the distribution of seasonal precipitation. From autumn to spring, water level fell below while that of Woedo stream remained the same all year round. Data on the water level observed in Woedo stream and Gangjung stream in every single minutes was applied to weir formula(equation of Oki and Govinda Rao) to calculate baseflow discharge. Also, using the data on current and water level calculated in Ongpo stream and Yeonwoe stream, water level-water flow rating was applied to assess base flow discharge.

• 한국기계가공학회지
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• 제15권5호
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• pp.131-136
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• 2016

Currently, an EDM tapping procedure has comprised some parts of the engraving discharge process for the press die. Usually, tapping has been used in cases where we are unable to mechanically machine using steelwork processes due to an increase in the hardness of a material after heat treatment in relation to a design change or missing process. Here, we analyze the influence of discharge tap shape on discharge time, discharge current, and the number of repetition conditions when a cold-work tool steel (STD11) has been treated with a discharge tapped by a screw-shaped cu electrode. The most important influence on processing condition has been determined to be the number of discharge repetitions. As this number increases, the angle reduction of a thread closes to an angle of the electrode via a power generation reduction. The optimal combination of conditions has been determined to be three discharge repetitions, $180{\mu}s$ of discharge time (same as existing regulations), and 25.4A of peak current. A 0.2749db advantage has emerged after comparing between this combination of optimal conditions and the SN rate of existing regulations.