• Composites Research
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• v.32 no.5
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• pp.237-242
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• 2019

In this research, a capacitive pressure sensor (Piezocapacitive Sensor) was fabricated using carbon black powder containing poly-dimethylsiloxane (PDMS) with micro-grid patterned surface. To investigate the effect of carbon black powder and micro-grid pattern on the sensor's performance, various sensors were fabricated with different carbon black powder concentration and grid pattern density. The performances of the developed sensors were compared in terms of operating range and sensitivity.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.2
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• pp.225-229
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• 2011

In this study, capacitive type pressure sensors based on low temperature co-fired ceramics (LTCC) technology for environmental monitoring were demonstrated. The LTCC is one of promising technology than is based one since it has many advantages (e.g., low cost production, high manufacturing yields and easy realizing 3D structure etc.) for sensor application. Especially, it has good mechanical and chemical properties for robust environmental application. The 3D LTCC diaphragm with thickness of 400 ${\mu}m$ were fabricated by laminating 4 green sheets using commercial powder (NEG, MLS 22C). To evaluate the sensing properties of the different cavity areas, two types of diaphragm which had different cavity areas with 25, 49 $mm^2$ respectively, were fabricated. To realize capacitive type pressure sensor, the Au top electrode was fabricated using thermal evaporator and the bottome electrode was compressed using aluminium foil. The sensing properties of the fabricated sensors showed linear characteristic under different pressure (0~30 psi) using pressure measurement system.

• Journal of the Semiconductor & Display Technology
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• v.6 no.4
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• pp.23-27
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• 2007

Rotary stages in semiconductor, display industry and many other fields require challenging accuracy to perform their functions properly. Especially, Axis of rotation error on rotary system is significant; such as the spindle error motion of the aligner, wire bonder and inspector machine which result in the poor quality products. To evaluate and improve the performance of such precision rotary stage, undesired movements on the other 5 degrees of freedom of the rotary stage must be measured and analyzed. In this paper, we have measured the three translations and two tilt motions of the worm gear type spindle with high precision capacitive sensors. To obtain the radial error motion, we have used Donaldson's reversal technique. And the axial components of the spindle tilt error motion can be obtained accurately from the axial direction outputs of sensors by Estler face motion reversal technique. Further more we have designed and developed the sensor mounting jig with standard cylinder for reversal method.

• Journal of Convergence for Information Technology
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• v.8 no.5
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• pp.95-100
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• 2018

The metal oxide/graphene nanocomposites are promising functional materials for high capacitive electrode material of secondary batteries, and high sensitive material of high performance gas sensors. In this study, vanadium dioxide($VO_2$) nanostructrures were grown on CVD graphene which was synthesized on Cu foil by thermal CVD, and exfoliated graphene which was exfoliated from highly oriented pyrolytic graphite(HOPG) using a vapor transport method. As results, $VO_2$ nanostructures on CVD graphene were grown preferential growth on abundant functional groups of graphene grain boundaries. The functional groups are served to nucleation site of $VO_2$ nanostructures. On the other hand, 2D & 3D $VO_2$ nanostructures were grown on exfoliated graphene due to uniformly distributed functional groups on exfoliated graphene surface. The characteristics of morphology controlled growth of $VO_2$/graphene nanocomposites would be applied to fabrication process for high capacitive electrode materials of secondary batteries, and high sensitive materials of gas sensors.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.11 s.176
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• pp.135-141
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• 2005

Measurement of five DOF motion errors in a ultra precision feed table was attempted in this study. Yaw and pitch error were measured by using a laser interferometer and roll error was measured by using the reversal method. Linear motion errors in the vertical and horizontal directions were measured by using the sequential two point method. In this case, influence of angular motion errors was compensated by using the previously measured ones by the laser interferometer and the reversal method. The capacitive type sensors and an optical straight edge were used in the reversal method and the sequential two point method. Influence of thermal deformation on sensor jig was investgated and minimized by the periodic measurement according to the variation of room temperature. Deviation of gain between sensors was also compensated using the step response data. 5 DOF motion errors of a hydrostatic table driven by the linear motor werer tested using the measurement method. In the horizontal direction, measuring accuracies for the linear and angular motion were within ${\pm}0.02\;{\mu}m$ and ${\pm}0.04$ arcsec, respectively. In the vertical direction, they were within ${\pm}0.02{\mu}m$ and ${\pm}0.05$ arcsec. From these results, it was found that the introduced measurement method was very effective to measure 5 DOF motion errors of the ultra precision feed tables.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2004.11a
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• pp.130-136
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• 2004

Presence of water in the lubricating oils could be one of the first indicators of potentially expensive and possibly catastrophic failure of the machine as it may cause displace the oil films to prevent the lubrication function of the oil or chemically react with many oil additives resulting in the oil degradation. In order to detect water content quantitatively in lubricating oils many methods and sensors has been developed. Among these, capacitive sensors including sensitive layer, whose dielectric factor changes according to the water content absorbed in the layer, are proposed mainly in the market. But these sensors are not sensitive to a high water content. Besides, the absorbing layer soils in time. In this work, an evaporation of water moisture from oil into air volume above lubricant surface and condensation of water vapor at a cooling surface was used to measure water content quantitatively in an lubricating oil. Laboratory test results of a prototype sensor were presented. Test results showed that the proposed method could be avaliable to measure a low levels of oil moisture.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.12
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• pp.882-887
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• 2013

We investigated a SiC-based hydrogen gas sensor with metal-insulator-semiconductor (MIS) structure for high temperature process monitoring and leak detection applications. The sensor was fabricated by Pd/$Ta_2O_5$/SiC structure, and a thin tantalum oxide ($Ta_2O_5$) layer was exploited with the purpose of sensitivity improvement, because tantalum oxide has good stability at high temperature as well as high permeability for hydrogen gas. In the experiment, dependence of I-V characteristics and capacitance response properties on hydrogen gas concentrations from 0 to 2,000 ppm was analyzed at room temperature to $500^{\circ}C$. As the result, our sensor exploiting a $Ta_2O_5$ dielectric layer showed possibilities with regard to use in hydrogen gas sensors for high-temperature applications.

• Journal of Sensor Science and Technology
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• v.26 no.2
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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.

• Journal of Sensor Science and Technology
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• v.13 no.5
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• pp.363-368
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• 2004

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 $50{\Omega}$ 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.

• 한국HCI학회:학술대회논문집
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• 2007.02a
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• pp.573-577
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• 2007

터치 센서를 이용한 휴대단말용 인터페이스가 다양하게 개발되면서 차세대 인터랙션 수단으로서 많은 주목을 받고 있지만, 버튼 인터페이스에 비해 오동작에 취약하고 터치 인터페이스만의 차별성을 확보하지 못하고 있는 실정이다. 본 논문에서는 터치 드래그 동작을 주요 인터랙션 수단으로 활용한 모바일 기기용 사용자 인터페이스를 개발하여 오동작을 최소화하고 사용자가 조작할 때 즐거움을 줄 수 있는 UI 요소로 활용할 수 있도록 하였다. 본 논문에서 개발한 터치 인터페이스는 기기의 내부/외부 방향의 스크롤 동작을 각각 drag-in/drag-out 동작으로 칭하고 이러한 드래그 동작을 응용 프로그램의 실행과 종료에 할당하였으며 터치 센서를 따라 움직이는 스크를 동작은 기존과 동일하게 일반적인 스크롤 행위를 지시하는데 적용하였다. 제안한 인터랙션 방법은 터치 센서의 형태에 따라 크게 두 가지 방식으로 구현하였다. 첫 번째 방법은 기기 스크린 외곽에 터치 센서를 이열(二列) 배치하여, 터치스크린을 사용하지 않고도 스크린 주변의 터치 센서를 활용한 drag-in/out 동작의 감지가 가능하도록 하였다. 두 번째 구현 방법은 정전용량형 터치 센서 IC를 활용해 터치 스크린 기능과 함께 스크린 주변의 기기 케이스의 일부까지도 사용자의 접촉을 감지할 수 있도록 하였다. 기존 저항 방식 터치 스크린과 달리 본 논문에서 활용한 방식은 스크린과 케이스에서 동시에 터치를 감지할 수 있으며, 다접점 감지 알고리즘의 개발로 두 개의 손가락을 이용한 다양한 터치 인터랙션으로 활용할 수 있다.