• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.1191_1192
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• 2009

The objective of levitation control design is to stabilize a levitation system, or obtain certain transient response, bandwidth, and steady state error. An air gap signal from the each corner is important parameter to design levitation controller. A levitation controller using gap signals with measurement delay time can not make a expected performance. In this paper, a new air gap estimator to improve the performance of levitation controller is proposed. The estimated gap signal which has little measurement delay time is used as a feedback value in the levitation controller.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집D
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• pp.834-839
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• 2001

Calandria tube wrapping each pressure tube is one of the key structural components of CANDU reactor(Calandria) which is consisted of many pressure tubes containing nuclear fuel assemblies. As the Calandria tube(made of zirconium alloy) is sagging due to its thermal and irradiation creep during the plant operation, it possibly contacts with liquid injection nozzle crossing beneath the Calandria tube, which subsequently results in difficulties on the safe operation. It is therefore necessary to check the gap for the confirmation of no contacts between the two tubes, Calandria tube and liquid injection tube, with a proper measure during the life of plant. In this study, an ultrasonic measurement method was selected among several methods investigated. The ultrasonic device being developed for the measurement of the gap was introduced and its preliminary performance test results were presented here. The gap between LIN and CT at site was measured using by this ultrasonic device at site.

• 대한기계학회논문집A
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• 제26권2호
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• pp.254-259
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• 2002

A variable air-gap type system is widely used for inductive precision position measurement systems. This type transducer has high sensitivity but lacks a linear measurement range due to structural nonlinearity. Furthermore, as measurement range increases, linearity error is also increased. The alternative is a variable overlap-area type system. The sensitivity of this type is determined by the initial air-gap dimension, keeps the original value and does not deteriorate linearity in spite of the variations of the measuring range.

• 한국정밀공학회지
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• 제26권4호
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• pp.107-113
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• 2009

In this paper, we studied of measurement the vibration of natural frequency using optical fiber sensor. The boring bar for measurement of vibration in use optical fiber sensor has the advantage of direct measure for the frequency than accelerometer. Because it deal with output value on electrical signal of optical fiber in physical disturbance when it measures the frequency of vibration. The optical fiber sensor measured the vibration of boring bar by the gap in sensing jig while optical fiber just kept contact with boring bar. A prototype system was composed of jig part with gap and optical system part. In this paper, we found out the possibility to measurement of vibration by the gap in use optical fiber.

• 마이크로전자및패키징학회지
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• 제9권3호
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• pp.7-12
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• 2002

LTCC(Low temperature Cofiring Ceramics)기판의 고주파특성 평가에 있어서, 기판은 전극 패터닝 공정 방식이 결합된 하나의 시스템으로 평가되어야 한다. LTCC의 경우 시스템마다 상이한 소결 수축 과정, 전극과 기판의 접합 특성(matching) 차이, 사용 도체간 전기 전도도의 차이 등으로 인해 유전 특성 및 신호손실이 차이를 나타내었다. 본 논문에서는 FR-4, Duroid, Teflon등 기존의 상용 PCB(Printed Circuit Board) 와의 상대적인 비교를 통해 현재 사용되고 있는 LTCC 기판의 주파수 응용도를 확인하였으며, 20 ㎓까지 측정을 수행하였다. 측정방식으로는 Ring 공진기와 Series-Gap 공진기를 활용한 마이크로 스트립 공진기 방법을 채택하였으며, 실험 결과 기판손실 측정은 Ring 공진기 방식이 유효하였으며 유전률 측정은 Series-Gap 공진기 방식이 유효함을 확인하였다. 또한 주파수 증가에 따라 LTCC 기판의 전극 패터닝 방식이 시스템의 손실에 미치는 영향에 대해 분석하였다.

• 전기학회논문지
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• 제68권1호
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• pp.77-82
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• 2019

In this paper, a 0.6~6GHz quad-ridge horn antenna which can be used for the antenna measurement of 5.8GHz WiFi system from lowest frequency band of mobile LTE (Long Term Evolution) is designed and implemented. The quad-ridge horn antenna has quadruple ridges of exponential function, a back-short and a cavity. Based on this structure, we design the cavity size, ridge gap and feed gap to have broadband characteristics. For implementation, the plates material of aluminum and copper are used for the horn and four ridges, respectively. And the insulator supports are used to maintain the gap between ridges. By measurement, antenna has the gain of 6.2~13.35dBi with the return loss of less than -6dB (under VSWR 3 : 1) in the entire design band. The results of this study can be widely used to the antenna studies on the mobile communication including low frequency band of LTE, the EMI measurement and the standard calibration measurement.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1996년도 춘계학술대회논문집; 부산수산대학교, 10 May 1996
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• pp.95-99
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• 1996

In this paper, we proposed a method to measure the gap between the magnetic pole and the levitated object applying the inductance characteristic which vary according to gap. We made a driving circuit which supply the control input PWM(Pulse Width Modulation) signal and the carrier PWM signal to estimate the gap. Because the inductance is a function of gap, and the current of the carrier signal is a function of the inductance. We investigated the validity of the proposed method through the experimental results.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
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• pp.373-376
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• 2004

The measurement of diffraction of LCOS microdisplay with various pixel size, interpixel gap, pixel height and coatings demonstrates that pixel size is the leading factor for diffraction loss, while the role of varying pixel gap is less significant comparatively. One-dimensional diffraction simulation is found to be in good agreement with the measurement. Noticeable deviation occurs when pixel size is as small as 8um.

• 소음진동
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• 제5권1호
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• pp.49-57
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• 1995

An electronic circuit device is developed such that the displacement between an electromagnet and a moving target can be estimated from the coil current measurement, and then applied to an active magnetic bearing system. In order to levitate the shaft without using displacement sensor the stable control gains are obtained from the linearized model which includes the gap estimation circuit. Experimental results show that the shaft, by the estimated gap feedback, can be levitated within $\pm$6 ${\mu}m$ positioning error.

• 한국생활과학회지
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• 제13권6호
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• pp.959-966
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• 2004

The purpose of this research is to analyze the shape of gathered skirts made by different gatherings. The shape of gathered skirts is affected by the amount of the gatherings that control fullness along a waistline seam. The gap also has an effect on the shape. We made a few experiments to make gathered skirts in different gathering conditions. The conditions include two types of ratio of gathers, which were given the total amount of gathering, and two types of spread of gathers, which were calculated for waist and hip. Experiments were conducted to figure out the dressed shape through 3-D measurement Exyma- WBS, and also to investigate the proportion, area distribution, and gap of the shape of gathered skirts on the horizontal section map with Rapid Form 2004 SP3, a software for 3-D shape analysis. As the results show, there were differences among the proportion, area distribution, and gap of the dressed shape. It showed that the shape on the horizontal section map was different because the shape between waist and hip per parts on body was not the same.