• 한국반도체및디스플레이장비학회:학술대회논문집
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• 한국반도체및디스플레이장비학회 2002년도 추계학술대회 발표 논문집
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• pp.59-63
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• 2002

This paper reports on the fabrication process and characteristics of a ceramic thin-film pressure sensor based on Ta-N strain-gauges for harsh environment applications. The Ta-N thin-film strain-gauges are sputter-deposited on a thermally oxidized micromachined Si diaphragms with buried cavities for overpressure tolerance. The proposed device takes advantage of the good mechanical properties of single-crystalline Si as a diaphragm fabricated by SDB and electrochemical etch-stop technology, and in order to extend the temperature range, it has relatively higher resistance, stability and gauge factor of Ta-N thin-films more than other gauges. The fabricated pressure sensor presents a low temperature coefficient of resistance, high-sensitivity, low non-linearity and excellent temperature stability. The sensitivity is 1.21 ~ 1.097 mV/V.kgf/$\textrm{cm}^2$ in temperature ranges of 25~ $200^{\circ}C$ and a maximum non-linearity is 0.43 %FS.

• 한국산업정보학회논문지
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• 제6권1호
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• pp.70-76
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• 2001

NdFeB로 만들어진 permanent magnet dc driver는 많은 분야에서 사용된다. 그중 소형 disk type servo driver는 컴퓨터의 hard disk driver나 floppy driver등과 같은 소형기기의 구동용으로 사용된다. 기존의 dc drive는 coil를 감아 winding으로 사용한다. 만들어진 driver에는 coper printed multilayer winding을 사용하였다. 이 논문에서는 thin film multilayer winding의 제조방법, 특성에 관하여 논한다. 또한 dc driver의 commutation를 위해 사용되는 hallsensor 대신에 비 선형 특성의 MR sensor를 선형화시켜 driver의 commutation에 사용하였으며 이렇게 만들어진 소형 driver의 rpm, torque등의 특성을 연구하였다.

• 한국가시화정보학회지
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• 제9권2호
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• pp.34-39
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• 2011

This paper presents a novel direct fabrication method of the thin metal film RTD temperature sensor array on an arbitrary curved surface by using MEMS technology to measure a distributed temperature field up to $300^{\circ}C$ without disturbing a fluid flow. In order to overcome the difficulty in the three dimensional photography of sensor patterning, the UV pre-irradiated photosensitive dry film resist technology has been developed newly. This method was applied to the fabrication of the temperature sensor array on a glass tube, which is arranged parallel and transverse to a main flow. Gold was used as a temperature sensing material. The resistance change was measured in a thermally controlled oven by increasing the environmental temperature. The linear increase in resistance change and a constant slope were obtained. Also, the sensitivity of each RTD temperature sensor was evaluated.

• 센서학회지
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• 제16권2호
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• pp.91-96
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• 2007

The characteristic of tellurium thin films was studied for detecting nitrogen dioxide gas at room temperature. The film was deposited on $Al_{2}O_{3}$ substrate by using thermal evaporator. The subsequent process was heat treatment by several conditions. (temperature, flowed gases) Surface and grain boundary was investigated using SEM. The results showed that resistance of the tellurium film decreases reversibly in the presence of nitrogen dioxide. The sensitivity of this device depends on the gas concentration and detect lower concentrations less than 10 ppm.

• 한국재료학회지
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• 제6권7호
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• pp.716-722
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• 1996

박막 형 가스 센서의 막 두께가 가스 감지 특성에 미치는 영향을 단순화된 모델로부터 수식으로 유도하여 해석하였고, 그것을 ${SnO}_{2}$와 CuO-${SnO}_{2}$ 박막의 ${H}_{2}S$ 감응 특성에 대한 실험 결과에 적용하였다. 유도된 수식으로부터 박막 가스 센서의 가스 감지 특성은 가스의 박막 안으로의 확산성에 크게 의존하며, 그 가스 확산성은 박막의 두께, 가스의 센서 재료의 반응성, 작동 온도 등에 의해서 결정됨을 알 수 있었다. 또한 이 수식은 CuO-${SnO}_{2}$ 박막의 ${H}_{2}S$ 감응 특성에 대한 실험 결과와 비교적 잘 일치하였고, CuO-${SnO}_{2}$ 박막과 ${SnO}_{2}$ 박막의 서로 판이한 ${H}_{2}S$ 감응 특성에 대한 설명에 적용되었다. 이로부터, 일반적인 산화물 반도체식 가스 센서의 가스 감지 특성이 가스 확산성에 의해서 어떻게 지배되는가를 구체적으로 제안하였다.

• Journal of Biosystems Engineering
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• 제37권3호
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• pp.209-213
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• 2012

Purpose: This study was performed to develop a simple, disposable thin-film optical nitrate sensor. Methods: The sensor was fabricated by applying a nitrate-selective polymer membrane on the surface of a thin polyester film. The membrane was composed of polyvinylchloride (PVC), plasticizer, fluorescent dye, and nitrate-selective ionophore. Fluorescence intensity of the sensor increased on contact with a nitrate solution. The fluorescence response of the optical nitrate sensor was measured with a commercial fluorospectrometer. Results: The optical sensor exhibited linear response over four concentration decades. Conclusions: Nitrate ion concentrations in plant nutrient solutions can be determined by direct optical measurements without any conditioning before measurements.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.1842-1846
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• 2008

This work reports development of novel liquid-level sensors based on the $3{\omega}$ method. The sensors determine the liquid level by measuring the thermal response as in the conventional hot-wire technique. However the sensors employ an AC heating method to enhance the sensitivity, noise resistance and time response. Also, the microfabricated thin-film structure of the sensor provides mass-producibility as well as improved sensor performance owing to the increase in the surface-volume ratio of the sensor. Two different types of the sensor are developed: one for point detection of the fluid phase and the other for monitoring continuous variation of liquid level. Notable is that the performance of the sensor is not considerably affected by the liquid flow.

• Composites Research
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• 제15권5호
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• pp.7-13
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• 2002

압전필름센서는 복합재 구조물의 저속충격응답을 관측하기에 우수한 특성을 지니고 있다. 본 연구에서는 Gr/Ep 복합재 적층판이 손상이 발생할 수 있을 정도의 충격에너지를 받았을 때 압전필름센서 신호를 이용하여 충격거동을 모니터링할 수 있는 가능성에 대하여 고찰하였다. 손상이 발생하지 않는 저에너지 충격조건부터 국부적인 손상을 유발할 수 있는 충격조건까지 압전필름센서가 부착된 Gr/Ep 복합재 적층판에 대하여 16가지의 저속충격시험을 수행하였다. 세 가지 조거의 충격시험에서 기지균열 및 층간분리 등의 국부적인 손상이 발생하였으나, 충격력과, 변위, 변형률, 압전센서 신호와의 관계를 이용한 선형해석 모델을 사용하여 충격하중에 의한 복합재 적층판의 응답을 예측하는 정방향 문제와 압전센서 신호로부터 충격력을 복원하는 역방향 문제에서 시험과 해석 결과는 비교적 잘 일치하는 경향을 보였다. 복원된 충격력으로부터 국부적인 손상이 발생할 정도의 충격까지는 압전필름센서 신호를 이용하여 충격력을 정확히 복원할 수 있음을 확인하였다.

• 한국재료학회지
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• 제19권6호
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• pp.325-329
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• 2009

Titanium dioxide thin films were fabricated as hydrogen sensors and its sensing properties were tested. The titanium was deposited on a $SiO_2$/Si substrate by the DC magnetron sputtering method and was oxidized at an optimized temperature of $850^{\circ}C$ in air. The titanium film originally had smooth surface morphology, but the film agglomerated to nano-size grains when the temperature reached oxidation temperature where it formed titanium oxide with a rutile structure. The oxide thin film formed by grains of tens of nanometers size also showed many short cracks and voids between the grains. The response to 1% hydrogen gas was ${\sim}2{\times}10^6$ at the optimum sensing temperature of $200^{\circ}C$, and ${\sim}10^3$ at room temperature. This extremely high sensitivity of the thin film to hydrogen was due partly to the porous structure of the nano-sized sensing particles. Other sensor properties were also examined.

• Transactions on Electrical and Electronic Materials
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• 제13권1호
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• pp.27-30
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• 2012

This paper proposes a micro gas sensor for measuring $H_2S$ gas. This is based on a $SnO_2$-CuO multi-layer thin film. The sensor has a silicon diaphragm, micro heater, and sensing layers. The micro heater is embedded in the sensing layer in order to increase the temperature to an operating temperature. The $SnO_2$-CuO multi layer film is prepared by the alternating deposition method and thermal oxidation which uses an electron beam evaporator and a thermal furnace. To determine the effect of the number of layers, five sets of films are prepared, each with different number of layers. The sensitivities are measured by applying $H_2S$ gas. It has a concentration of 1 ppm at an operating temperature of $270^{\circ}C$. At the same total thickness, the sensitivity of the sensor with multi sensing layers was improved, compared to the sensor with one sensing layer. The sensitivity of the sensor with five layers to 1 ppm of $H_2S$ gas is approximately 68%. This is approximately 12% more than that of a sensor with one-layer.