무인항공기 연료량 측정 장치 신호모사를 위한 연구

정재헌,이수철,박건국,배경호,안상석,이정원 한국항공우주학회 2013 한국항공우주학회 학술발표회 논문집 Vol.2013 No.11

연료량 신호모사장비는 연료량 측정 장치의 성능과 기능을 검사하기 위한 장비이다. 항공기 기체에 장착된 연료량 측정 장치의 Sensor인 Probe에 연료량을 모사해주는 방법으로 다음 세 가지 경우를 찾을 수 있다. 연료량 측정을 위한 Probe를 실제 연료에 노출시켜 모사하고자 하는 연료량만큼의 연료 높이를 모사하는 방법, Probe의 커패시턴스를 직접 모사하는 방법 그리고 연료량 측정 Probe의 전기적 출력 값을 모사하여 연료량 측정 장치로 전송하는 방법이 있다. 전자의 경우 취급과 운용의 문제점이 있으며, 커패시턴스를 직접 모사하는 방법은 비용과 기술적인 어려움이 따른다. 이러한 문제점을 해결하고자 연료량 측정 장치에 Probe의 출력 신호를 모사하는 장비 개발에 대한 연구를 수행하였다. Fuel Quantity Simulator is a device to examine the performance and function of Fuel Gauging System. There are three methods to simulate the amount of fuel to the Probe which is a sensor of Fuel Gauging System installed in the fuselage of an aircraft. The first is to expose the Probe to the actual fuel so that we can simulate the amount of fuel as high as we want. The second is to directly simulate the capacitance of the Probe and the third is to simulate the electric output signal of the fuel gauging Probe. The first method could have to the difficulties to handle the equipments. The second method also accompanies cost and technical issues. To overcome these problems, we carried out researches to develop an equipment that can simulate Probe output signal to the Fuel Gauging System.

좁은 간격 CCP 전원의 전극과 측면 벽 사이 플라즈마 분포

최명선,장윤창,이석환,김곤호 한국반도체디스플레이기술학회 2014 반도체디스플레이기술학회지 Vol.13 No.4

The plasma density distribution in between the electrode and lateral wall of a narrow gap CCP was investigated. The plasma density distribution was obtained using single Langmuir probe, having two peaks of density distribution at the center of electrode and at the peripheral area of electrodes. The plasma density distribution was compared with the RF fluctuation of plasma potential taken from capacitive probe. Ionization reactions obtained from numerical analysis using CFD-ACE+ fluid model based code. The peaks in two region for plasma density and voltage fluctuation have similar spatial distribution according to input power. It was found that plasma density distribution between the electrode and the lateral wall is closely related with the local ionization.

In situ monitoring and prediction of progressive joint wear using Bayesian statistics

An, D.,Choi, J.H.,Schmitz, T.L.,Kim, N.H. Elsevier Sequoia [etc.] 2011 Wear: An international journal on the science and Vol.270 No.11

In this paper, a statistical methodology of estimating wear coefficient and predicting wear volume in a revolute joint using in situ measurement data is presented. An instrumented slider-crank mechanism that can measure the joint force and the relative motion between the pin and bushing is built. The former is measured using a load cell built onto a necked portion of the hollow steel pin, while the latter is measured using a capacitance probe. In order to isolate the effect of friction in other joints, a porous carbon air bearing for the revolute joint between the follower link and the slide stage, as well as a prismatic joint for the linear slide, are used. Based on the relative motion between the centers of the pin and bushing, the wear volumes are estimated at six different operating cycles. The Bayesian inference technique is used to update the distribution of wear coefficients, which incorporates in situ measurement data to obtain the posterior distribution. The Markov Chain Monte Carlo technique is employed to generate samples from the given distribution. The results show that it is possible to narrow the distribution of wear coefficients and to predict the future wear volume with reasonable confidence. The effect of the prior distribution on the wear coefficient is discussed by comparing with the non-informative case.

몰드변압기에서 용량성 프로브에 의한 부분방전 검출 기술

정광석,박대원,차현규,차상욱,길경석,Jung, Kwang-Seok,Park, Dae-Won,Cha, Hyeon-Kyu,Cha, Sang-Wook,Kil, Gyung-Suk 한국전기전자재료학회 2011 전기전자재료학회논문지 Vol.24 No.4

This paper dealt with a partial discharge (PD) detection method for insulation diagnosis in cast-resin transformers. To detect PD pulse, a planar-capacitive probe was designed and fabricated. The probe has no insulation problem and can be installed on cast-resin transformers even in operation since it does not connect with high voltage conductor. The PD measurement system consists of the capacitive probe, a coupling network of 100 [kHz] low-cutoff frequency, and an amplifier with a gain of 40 [dB] and a frequency bandwidth of 500 [Hz]~45 [MHz]. A plane-needle and a plane-plane electrode system were fabricated to simulate insulation defects in a cast-resin transformer. Sensitivity of the PD measurement system, which is evaluated by a standard calibrator was 0.35 [mV/pC] for positive and 0.45 [mV/pC] for negative, respectively. The PD detection by the capacitive probe was less sensitive than that by a coupling capacitor according to IEC 60270, but we could analyze the magnitude and the phase distribution of PD pulse.

가스절연개폐기에서 용량성 전압프로브를 이용한 부분방전의 측정

길경석,박대원,최수연,김일권,박찬용,Kil, Gyung-Suk,Park, Dae-Won,Choi, Su-Yeon,Kim, Il-Kwon,Park, Chan-Yong 한국전기전자재료학회 2008 전기전자재료학회논문지 Vol.21 No.1

An objective of this paper is to develop a partial discharge (PD) measurement device for monitoring gas insulated switches installed in power distribution system. A capacitive voltage probe was studied and designed to detect PD pulse without an electrical connection. The PD measurement device consists of the capacitive voltage probe attached outside of a bushing, a coupling network which attenuates AC voltage by 270 dB, and a low noise amplifier with the gain of 40 dB in ranges of 500 kHz${\sim}$20 MHz. The sensitivity of the prototype device calculated by a calibrator was 1.98 m V /pc. An application experiment was carried out in a 25.8 kV gas insulated switch and the peak pulse of 76.7 pC was detected. From the experimental results, it is expected that the PD measurement device can be applied to online monitoring system of gas insulated switches.

Capacitive load effect on sideband currents in a floating harmonic method with dual frequency probe bias

김경현,이무영,정진욱 한국진공학회 2019 한국진공학회 학술발표회초록집 Vol.2019 No.2

몰드변압기의 부분방전 검출기술에 관한 연구

박찬용,박대원,최재성,길경석,Park, Chan-Yong,Park, Dae-Won,Choi, Jae-Sung,Kil, Gyung-Suk 한국전기전자재료학회 2009 전기전자재료학회논문지 Vol.22 No.9

Transformer failures are mostly due to partial discharges (PDs) caused by the deteriorated insulation. It is, therefore, important to monitor PD occurrence in insulation system and prevent their deterioration. The presented paper deals with a PD detection method by a capacitive probe, which easily apply to cast - resin dry - type transformers. The PD detection system consists of a capacitive probe and a low noise amplifier having the frequency bandwidth of 500 $Hz{\sim}30$ MHz. In the experimental set-up, sensitivity of the system is 7.16 mV/pC.

용량성 프로브와 광전송회로를 이용한 광대역 전압측정장치

길경석 ( Gyung Suk Kil ),송재용 ( Jae Yong Song ),박대원 ( Dae Won Park ) 한국센서학회 2004 센서학회지 Vol.13 No.5

A reliable voltage measurement system is necessary to monitor status of power facilities in substations, which is easy to set up and is not influenced by electromagnetic interference in and around substation. In this paper, we described a voltage measurement system (VMS) which is composed of a capacitive voltage probe, an impedance converter, and an optical linker. To get a wide-band characteristic of the VMS, a high speed impedance converter was used, and the output impedance of the VMS was set at 50 Ω to match any types of observing instruments. The frequency bandwidth of the VMS. which was estimated by a step pulse, was ranges from 11.42 Hz to 13.65 MHz, and the VMS showed a good response characteristic in a high frequency domain such as impulse voltages as well as a commercial frequency voltage.

리액턴스의 변화를 이용한 정삼각형 마이크로스트립 패치 안테나의 대역폭 개선

이원희,이재욱,전승길,최홍주,허정,Lee, Won-Hui,Lee, Jae-Wook,Jeon, Seung-Gil,Choi, Hong-Ju,Hur, Jung 한국전자파학회 2003 한국전자파학회논문지 Vol.14 No.6

삼각형 패치 안테나에 대해 이론적인 방법과 실험을 통해 연구하였다. 삼각형 패치 안테나는 사각형 패치 안테나와 비슷한 복사 특성을 갖으나, 그 크기를 더 줄일 수 있다. 본 논문에서는 정삼각형 마이크로스트립 패치 안테나를 공동 모델을 사용하여 해석하고, 설계 하였다. 또한 대역폭 향상을 위해 커패시티브 갭과 공기층 갭을 이용하였다. 커패시티브 갭은 패치의 급전점 부근에서 사각형 모양으로 만들었고, 공기층 갭은 유전체 기판과 그라운드 사이에 삽입하여 프로브 인덕턴스를 조정하였다. 안테나 각 부분의 효과와 특성 해석을 위해 상업용 시뮬레이션 툴인 Ensemble 5.0을 사용하였다. 시뮬레이션과 실험을 통하여 삼각형 마이크로스트립 안테나의 대역폭 개선의 가능성을 발견하였다. Triangular patches have been studied, both theoretically and experimentally. We feund that provided radiation characteristics similar to those of rectangular patches, but with smaller size. In this paper, we designed an equilateral triangular microstrip patch antenna using cavity model analysis. Then, in order to improve narrow bandwidth, we add capacitive gap and air gap. Capacitive gap is located with square shape beside feeding point on the patch, and air gap is inserted between substrate dielectric and ground plane to adjust probe inductance. The analysis of characteristics and effects of each component was performed by commercial simulation tool, Ensemble 5.0. Throughout the simulation and experiment, we found the possibility of bandwidth enhancement in triangular microstrip antenna.

점적관개 시 토성별 습윤ㆍ건조 특성 비교

김학진(Hak-Jin Kim),손동욱(Dong-Wook Son),허승오(Seung-Oh Hur),노미영(Mi-Young Roh),정기열(Ki-Yuol Jung),박종민(Jong-Min Park),이중용(Joong-Yong Rhee),이동훈(Dong-Hoon Lee) (사)한국생물환경조절학회 2009 시설원예‧식물공장 Vol.18 No.4

본 연구에서는 정밀관수를 위한 관수시간, 점적라인 설치 등 관수시스템 설계를 위한 기초 데이터를 얻고자 점적관수 시 토성에 따른 물의 수분함량변화를 공간적, 시간적 변이의 차이를 구명하였다. 20㎝의 간격의 노즐로 설치된 1열 점적관을 이용 관수 하였을 경우 양토와 사양토내의 수분은 중심을 따라 대칭 형태를 유지하면서 이동하였으나 수분확산 폭은 양토가 더 넓고 속도가 느린 경향을 나타내었다. 상대적으로 높은 모래성분 함량을 갖는 양질사토의 경우는 낮은 수분 보유력으로 인하여 위치별 수분함량의 변화는 상대적으로 낮았으며 그만큼 물 빠짐정도가 큰 것으로 나타났다. 관수개시점과 종말점을 고려하였을 때 사양토의 경우 20㎝ 깊이에서 관수개시 30분 후에 수분의 포화가 이루어졌으나 양토와 양질사토의 경우는 약 80분이 소요되어 효율적인 수분공급 측면에서 관수시간은 토성별로 달리해야 하는 것으로 나타났다. 깊이 10㎝에서의 시간에 다른 토양수분의 감쇠특성은 지수함수의 형태를 나타내었으며 토양별 안정된 상태에서의 수분함량은 양토, 사양토, 양질사토 각각 17.6%, 6.2%, 4.2%로 예측되어 토성에 따라 잔여수분함량은 차이가 있음을 확인하였다. 토양수분함량과 토양수분퍼텐셜과의 관계를 나타내는 수분특성곡선은 시험 토양의 경우 모두 높은 결정계수를 갖는 지수함수로 근사가 가능하여 수분퍼텐셜을 이용하여 측정하는 재배시스템에서 대응하는 수분함량 예측에 유용한 관계식을 얻었다. Maintenance of adequate soil water content during the period of crop growth is necessary to support optimum plant growth and yields. A better understanding of soil water movement for precision irrigation would allow efficient supply of water to crops, thereby resulting in minimization of water drainage and contamination of ground water. This research reports on the characterization of spatial and temporal variations in water contents through three different textured soils, such as loam, sandy loam, and loamy sand, when water is applied on the soil surface using an one-line drip irrigation system and the soils are dried after the irrigation stops, respectively. Water contents through each soil profile were continuously monitored using three Sentek probes, each consisting of three capacitance sensors at 10, 20, and 30㎝ depths. Spatial variability in water content for each soil type was strongly influenced by soil textural class. There were big differences in wetting pattern and the rate of downward movement between loam and sandy loam soils, showing that the loam soil had a wider wetting pattern and a slower rate of downward movement than did the sandy loam soil. The wetting pattern in loamy sand soil was not apparent due to a low variability in water content (<10%) by a lower-water holding capacity as compared to those measured in the loam and sandy loam soils, implying that the rate of water drainage below a depth of 30㎝ was high. When soils were dried, there were highly exponential relationships between water content and time elapsed after irrigation stops (r²≥ 0.98). It was estimated that equilibrium moisture contents for loam, sandy loam, and loamy sand soils would be 17.6%, 6.2%, and 4.2%, respectively.