• 소음진동
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• 제6권3호
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• pp.357-362
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• 1996

The magnetic levitation system has great advantages, such as little friction, no lubrication, no noise and so on. But the magnetic levitation system need a stabilizing controller because it is a unstable, system in natural and it need a sensor for displacement measurement to control the system. In this paper, we proposed a sensorless method to measure the gap between the magnetic pole and the levitated object with application the inductance characteristic which vary according to gap. We made a driving circuit which supply simultaneously 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 could estimate the gap from the measurement of the current of the carrier signal. Finally, we investigated the validity of the proposed method through the experimental results.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2001년도 학술대회 논문집
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• pp.149-152
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• 2001

The Linear compressor is widely used in Stirling cryocooler for cooling of infrared sensor. The performance of Stirling cryocooler was mainly depending on how much pressure difference can be generated by compressor. The gap between cylinder and piston should be minimized to get high pressure difference, but too small gap cause failure in the cryocooler. In this study, the leakage rate through gap was investigated by using CFD method and simple thermodynamic relation. The results show compression ratio is decreased and leakage rate increased according to increasing gap.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.768-771
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• 2001

Non-contacting capacitive sensor, based on principle of the cross capacitor, for measuring of $\mu\textrm{m}$-order displacements have been fabricated and characterized. To overcome disadvantages of the existed capacitive sensors of parallel type with 2-electrodes and 3-electrodes, the developed new sensor was designed to have 4-electrodes, two of them used high and low electrode the other two used as guard electrodes, on a sapphire plate with diameter 17 mm and thickness 0.7 mm, and are symmetrically situated with a constant gap of 0.2 mm between the electrodes. This sensor can be used for measuring the distance between sensor and target not only the metallic but also non-metallic target without ground connection.

• 센서학회지
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• 제19권2호
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• pp.92-98
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• 2010

The capacitive sensor has a simple structure, compact size and low cost, but a small dynamic range. The small range is caused by use of gap variation. If the sensor takes area variation type with one plate moving horizontally, it can have a large measurable range. While the area variation has relatively low sensitivity, some studies have found methods to improve the sensitivity. Even though the methods are effective, parameters of the results are limited and 2 dimensional. This study provides more practical and 3 dimensional analysis and suggests relations between parameters. Using the results, the optimized design parameters of a high dynamic range capacitive sensor can be found.

• Journal of Magnetics
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• 제18권4호
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• pp.454-459
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• 2013

This paper deals with an optimal angle error reduction method of magnetic position sensor using hall effect elements. The angle detection simulation for the magnetic position sensor is performed by 3 dimensional finite element method and Taguchi method, one of the design of experiments. The magnetic position sensor is required to generate ideal sine and cosine waveforms from its hall effect elements according to rotation angle for precise angle information. However, the output signals are easy to include harmonics due to uneven magnetic field distribution from permanent magnet in the air-gap in the vicinity of hall effect elements. For the Taguchi method, three design parameters related to position of hall effect elements and shape of back yoke are selected. The characteristics of optimal magnetic position sensor are compared with those of original one in terms of simulation as well as experiment. Finally, the performances of the motor adopting original model and optimal model are represented for the purpose of verification of motor performance due to signals from magnetic position sensor.

• 한국광학회지
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• 제29권6호
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• pp.268-274
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• 2018

본 연구에서는 1차원 포토닉 크리스탈과 금속-유기 구조체 (MOF) 물질인 Hong Kong University of Science and Technology(HKUST-1)을 이용한 수분 감지 컬러 센서를 제안한다. 1차원 포토닉 크리스탈은 주기적인 굴절률 변화에 의해 포토닉 밴드갭이 존재하고, 특정한 파장 대역의 광 성분을 차단 및 반사한다. HKUST-1의 굴절률은 건조한 환경과 습한 환경에서 그 값이 서로 다르다. 여기서 우리는 포토닉 밴드갭의 유무를 활용하여 FDTD 시뮬레이션으로 센서를 설계하였다. 광학 해석 결과, 투과된 광의 색 변환보다 반사된 광의 색 변환이 우수하여 반사된 광을 이용하였다. 그리고 포토닉 밴드갭의 중심 파장이 550 nm인 경우, 건조한 환경 대비 습한 환경의 최대 피크 값이 약 9.5배로 증가했으며, 무채색에서 녹색으로 색 변환이 가능하여 센서로의 특성이 우수하였다. 본 연구 결과는 MOF 물질의 수분 감지 컬러 센서로의 활용을 제시하였으며, MOF 물질의 나노 구조 설계로 산업 디바이스로의 활용성도 확대할 것이다.

• 센서학회지
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• 제26권2호
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• pp.101-106
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• 2017

A novel intravenous (IV) infusion monitoring sensor is presented to measure the drop rate in the drip chamber of an IV infusion set. It is based on a capacitive proximity sensor and detects the variation of the longitudinal electric field induced by the drop falling into the drip chamber. Unlike the conventional capacitor sensor with two semi-cylindrical conductor plates, the proximity sensor for IV monitoring is composed of a pair of conductor rings which are mounted on the outer surface of the drip chamber with a specific gap between them. The characteristics of the proximity sensor for IV monitoring were investigated through three dimensional electrostatic simulations. It showed quite superior performances in comparison with the conventional capacitor sensor. Especially, the proposed proximity sensor exhibits consistent sensitivity regardless of its mounting position on the drip chamber, operates normally though the drip chamber is tilted and shows robustness to the changes of the drop size and the drip factor of the IV infusion set. Thus, the proximity sensor for IV monitoring is more suitable for use in actual environment of IV therapy compared with the conventional capacitor sensor.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 Proceedings ICPE 01 2001 International Conference on Power Electronics
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• pp.56-59
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• 2001

An effective method of detecting inter-turn short circuits on round rotor windings is described. Shorted-turns can have significant effects on a generator and its performance. A method of detecting inter-turn short circuits on rotor windings is described. The approach used is to measure the rate of change of the air-gap flux density wave when the rotor is at operating speed and excitation is applied to the field winding. The inter-turn short circuits sensor for synchronous generator's field winding has been developed. The sensor, installed in the generator air-gap, senses the slot leakage flux of field winding and produces a voltage waveform proportional to the rate of change of the flux. For identification of reliability for sensor, a inter-turn short circuits test was performed at the West-Inchon combined cycle power plant on gas turbine generator and steam turbine generator. This sensor will be used as a detecting of shorted-turn for field winding of synchronous generator. The purpose of this paper is to describe the design and operation of a sensitive inter-turn short circuits detector. In this paper, development of inter-turn short circuits sensor for field winding of synchronous generator and application in a field.

• 한국전기전자재료학회논문지
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• 제17권5호
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• pp.508-514
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• 2004

A fluxgate magnetic sensor consists of a solenoid excitation coil, pick-up coil, and magnetic core. We presents the effect of magnetic core shape in a micromachined fluxgate sensor. To observe the performance of fluxgate sensor with magnetic core side width and gap, side width of 125 ${\mu}{\textrm}{m}$, 250 ${\mu}{\textrm}{m}$, and 500 ${\mu}{\textrm}{m}$ were designed in a rectangular-ring shaped core and the gaps of 0 ${\mu}{\textrm}{m}$, 50 ${\mu}{\textrm}{m}$, and 100 ${\mu}{\textrm}{m}$ were also fabricated in a racetrack shaped core. The solenoid coils and magnetic core were separated by benzocyclobutane(BCB) which had high insulation and good planarization characters. Copper coil patterns of 10 ${\mu}{\textrm}{m}$ width and 6${\mu}{\textrm}{m}$ thickness were electroplated on Ti(300 $\AA$) / Cu(1500 $\AA$) seed layers. 3 ${\mu}{\textrm}{m}$ thick N $i_{0.8}$F $e_{0.2.}$(permalloy) film for the magnetic core was also electroplated under 2000 gauss to induce the magnetic anisotropy. The magnetic core had the high DC effective permeability of ∼1,300 and coercive field of ∼0.1 Oe. Because the magnetic cores of 500 ${\mu}{\textrm}{m}$ side width and 0 gap had a low magnetic flux leakage, high sensitivity of ∼350 V/T were measured at excitation condition of 3 $V_{P-P}$ and 2 MHz square wave. The power consumption of ∼14 ㎽ was measured. The fabricated fluxgate sensor had the very small actual size of 3.0${\times}$1.7 $\textrm{mm}^2$. When two fluxgates were perpendicularly aligned in terrestrial field, their two-axis output signals were very useful to commercialize an electronic azimuth compass for the portable navigation system.m.m.m.

• 한국정보통신학회논문지
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• 제10권7호
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• pp.1326-1331
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• 2006

일반적으로 용접 Root 캡은 여러 가지 용접 결함들 중에 용접 품질을 저하시키는 중요한 요인 중의 하나이다. Gas metal arc welding (GMAW)에서 root 갭은 용접 전류, 아크 전압, 용적률 등과 같은 여러 가지 용접 파라미터들에 영향을 미친다. 그러나 용접 공정의 비선형성 때문에 root 갭과 많은 용접 파라미터들 사이의 관계를 분석하기가 힘들다. 그리고 아크센서를 사용하였을 경우, 감지된 신호에 대한 신호처리가 어렵지만 가격이 저렴하고 자동화하기가 쉬우므로 현재의 산업공정에서 대부분 아크센서가 사용되고 있다. 지금까지 언급된 여러 가지 어려운 문제점과 아크센서의 특정 때문에 본 논문에서는 GMAW에서 root 갭을 검출할 수 있는 적당한 용접 파라미터들을 선정하고, root 캡과 선정된 파라미터들의 관계를 인식할 수 있는 신경회로망을 이용하여 root 갭 검출 시스템을 설계하였다. 또한, 용접 품질의 검사에 용접 비드형상이 중요한 요인이다. 따라서 본 논문에서는 신경회로망으로 용접 파라미터와 용접 비드형상과의 관계를 인식하여, 용접 품질을 추정하고 용접 파라미터들의 효과를 분석할 수 있는 용접 비드 형상의 실시간 모니터링 시스템을 제안하여 여러 실험 데이터들을 기반으로 한 시뮬레이션을 통해 제안된 시스템이 root 갭을 검출하고 또한 용접 비드 형상을 실시간으로 모니터링이 가능함 보여준다.