• 한국지반신소재학회논문집
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• 제15권3호
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• pp.77-85
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• 2016

본 연구는 기존의 다짐관리 방법에서 다짐이 완료된 지반의 일부를 손상시켜야 하는 단점을 해결하기 위하여 진행되었다. 본 연구를 통하여 판형 Probe를 제작하였고, 제작한 Probe에 탄성파 측정 장치인 Piezoelectric stack을 결합하였다. 개발한 TDR 시스템을 이용하여 시간에 따른 개량토의 강도 변화를 측정하였다. 실험 결과, 압축탄성계수 및 전단탄성계수는 각각 78.92MPa에서 587.09MPa, 31.53MPa에서 182.44MPa로 증가함을 확인할 수 있었다. 실험 결과를 통하여 개발한 TDR 시스템을 이용하여 현장에서 개량지반의 시간경과에 따라 지반개량효과 및 다짐관리에 유용하게 활용할 것으로 기대된다.

• Nuclear Engineering and Technology
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• 제54권10호
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• pp.3614-3619
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• 2022

To operate the ion cyclotron resonance heating (ICRH) antennas in a better heating state and produce relatively low impurities, it is necessary to control the antenna spectrum by changing the antenna phasing. As the electrical length of the antenna feeding transmission lines is changing as a matter of the standing wave pattern at the ceramic supports, 90° elbows, T-connectors and antenna loops, we chose to measure the current at the grounding points of the antenna loops by antenna strap probe. The voltage drops along a small, several millimeter-long paths at the end of the antenna loops give a signal that is proportional to the current in the antenna loop. Through the simulation of the antenna strap probe and the actual measurement of the antenna phasing under vacuum conditions, the reliability of the antenna strap probe based diagnostic system have been successfully proved. Moreover, this system was successfully applied to the ICRH daily experiments in the spring of 2021. In the near future, the active real-time feedback control of the antenna phasing system will be developed based on this diagnostic system in the EAST tokamak.

• 한국광학회지
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• 제31권1호
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• pp.13-19
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• 2020

광섬유 사냑 간섭형 센서를 이용해 수중 음향을 측정하기 위하여 링형 탐촉자를 적용하는 경우 민감도를 이론과 실험을 통하여 조사한다. 링형 탐촉자는 단일 모드 광섬유를 지름 5 cm의 링형으로 감아서 접착제로 패키징하였다. 링형 탐촉자는 감지 광섬유의 길이를 46.84 m로 하여 제작한 A형 탐촉자와 감지 광섬유의 길이를 112.22 m로 한 B형 탐촉자를 준비하였다. 수중 음향 시험은 상용 음향 발생기와 1 m 떨어진 거리에서 링형 탐촉자를 사용하여 50, 70, 90 kHz의 주파수에 대하여 20~100 Pa의 음향 압력 범위에서 음향 민감도를 조사하는 실험을 수행하였다. 실험 결과, 링형 탐촉자는 주파수에 대하여 다른 민감도를 나타내었으며, 이론과 비교하기 위하여 평균값을 구하였다. 세 주파수에 대한 평균 민감도는 A 탐촉자와 B 탐촉자에 대하여 각각 25.48 × 10^-5, 60.79 × 10^-5 rad/Pa으로 측정되었으며, 이로부터 영률 보정 계수 c값을 0.35로 결정할 수 있었다.

• Journal of the Optical Society of Korea
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• 제1권2호
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• pp.94-99
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• 1997

In this paper, we calculate the four coefficients for the quantum theory of multiwave mixing including a local-field correction resulting from dipole-dipole interactions. We make contact with the semiclassical calculations of probe absorption and four-wave-mixing coupling coefficients, and illustrate the effects of local field corrections on resonance-fluorescence and coupled-mode-fluorescence spectra. The method uses the hybrid quantum-Langevin-equation master-equation approach of An and Sargent.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1998년도 추계종합학술대회 논문집
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• pp.335-338
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• 1998

This paper presents calculated results for the infinite phased arrays of the probe-fed rectagualr microstrip patches. A numerical model that is based on a rigorous Green's function and galerkin solutionsis is described. In an arbitrary scan plane, the input impedance and the input reflection coefficient versus the scand angle are calculated. The effects of substrate parameters on the phased arry antenna are considered. The scan blindness phenomenon due to the surface wave is observed and the input impedance bandwidth in the arbitrary scan plane is calculated.

• 한국해양공학회지
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• 제11권2호
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• pp.107-112
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• 1997

본 연구는 자유표면 인삭을 위한 실험 기법 개발에 관한 연구이다. 2차원 수중익에 의해 발생되는 자유표면파를 연구대상으로 삼았다. 실험은 회류수조에서 행하였다. NACA 0012 수중익을 여러가지 길이와 2가지양각에 대해서 실험한 결과 생기는 비선형 자유표면 파를 인식할 수 있도록 영상처리 기술을 도입하였다. 실헙결과 얻은 자유표면 형상을 다른 연구자의 결과와 비교하였다. 비교결과 영상처리의 기법이 자유표면을 인식하는데 대단히 유용한 도구임을 알 수 있었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1987년도 정기총회 및 창립40주년기념 학술대회 학회본부
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• pp.300-303
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• 1987

A microwave plasma generating system has been designed to study the properties of plasma. A microwave(2.45GHz) generated by the magnetron is transmitted to the cylindrical cavity through the the rectangular wave guide to generate hydrogen plasma. The electron temperature and the plasma density are measured by the Double Langmuir probe. A dilectric such as alumina is heated by the microwave add plasma. The surface temperature varies with the neutral gas pressure.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2000년도 International Symposium on Magnetics The 2000 Fall Conference
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• pp.325-326
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• 2000

Low temperature diagnosis was performed as a probe for the integrity of MTJ(Magnetic tunnel junction) process which is optimised for the given plasma oxidation condition. TMR ratio increased slowly with decreasing temperature than that expected from spin wave exitation theory〔1〕. Junction resistance (RJ) does not follow T$\^$-$\frac{1}{2}$/ law below 200 K, indicating another conduction path besides spin polarized tunneling is involved at low temperature. Temperature dependence of conductance dip and bias dependence of TMR with temperature are discussed, from which the quality of tunnel barrier and its formation process can be inferred.

• 한국정밀공학회지
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• 제13권11호
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• pp.92-99
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• 1996

The contact pressure in jointed plates was measured by means of an improved ultrasonic technique. In order to get calibration curve, the relationship between contact pressure and ratio of boundary and bottom echo of normal beam probes were obtained for the calibration blocks with various surface roughness. The ratio of boundary and bottom echoes were measured for the upper/under plates locally compressed with uniform pressure, and the distribution of contact pressure was obtaines. The measured pressure has a good agreement with results of FEM analysis. Thus the proposed ultrasonic method in this work is very useful to measure the contact pressure.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.508-508
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• 2012

CST microwave studio is used to simulate the plasma profile of the 450mm CCP source. Standing wave effect becomes important at the high frequency as the electrode radius increases. To solve plasma non-uniformity problem, we designed multi electrode chamber to decreasing standing wave effect. Simulation showed the ratio of input power of each electrode is related with electric field strength. The multi electrode was constructed and measured by 2D probe arrays using floating harmonic method. Uniformity of 450 mm CCP was changed by the ratio of input power of each electrode. We described this dependence with circuit model.