• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.910-912
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• 2015

In this paper, we designed the novel capacitive sensor and system for measuring the position of the piston in hydraulic cylinder. The magnetic or LVDT sensors have been widely used to measure the position of the piston because of its high accuracy, but these types of sensor are very expensive and have difficulty in use because of its complexity. To overcome these disadvantages, we studied the optimized non-contact capacitive sensor and designed detecting system for accurate measuring the location of piston in hydraulic cylinder. The proposed capacitive sensor and detecting system have the possibility of practical use for hydraulic cylinder through experiments.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.2061_2062
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• 2009

Within serviced period of time in transformer, thermal stress is the most influential parameter affecting the aging behavior of an insulation system. The thermal stress on the insulation system may occur from operation in a high temperature environment due to Joule's heat at winding coils. This paper describes a development of capacitive sensor and preventive diagnosis techniques for electrical insulating oil, widely used for power and distribution transformer. To survey the dielectric properties of the virgin and used mineral insulating oil, we utilized the highly precise measuring system of KRISS. And the results were used to determine the design factors of the sensor. To evaluate diagnosis by the sensor, we performed accelerated aging test about insulating oils. The condition of aged specimens were investigated by measurements of relative permittivity i.e. capacitance change by capacitive sensor.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.9
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• pp.976-981
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• 2009

MEMS capacitive gap sensor is developed for measuring abrasion depth of gun barrel rifling. Measuring abrasion depth of gun barrel rifling is very important because it is related with exactness of firing and life of arms. The method using a gap sensor is not to hurt rifling. And it can measure abrasion depth through minimum shooting, because the developed gap sensor can measure from $1{\mu}m{\sim}12{\mu}m$ using Polydimethylsiloxane(PDMS) material and making a stretchable electrode on PDMS. And it's resolution is 1 ${\mu}m$ using capacitive method and MEMS technology.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.9
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• pp.566-570
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• 2014

Electrode pattern effects on the capacitive humidity sensor were investigated. The fabrication of the capacitive humidity sensor was formed with three steps. The bottom electrode was formed on the silicon substrate with Pt/Ti thin layer by using shadow mask and e-beam evaporator. The photo sensitive polyimide was formed on the bottom electrode by using photolithography process as a humidity sensitive thin film. The upper electrode was formed on the polyimide thin film with Pt/Ti thin layer by using e-beam evaporator and lift-off method. Three electrode patterns, such as circle, square, and triangle pattern, were used and changed the sizes to investigate the effects. The capacitances of the sensors were decreased 622 to 584 pF with the area decreament of patterns 250,000 to $196,250{\mu}m^2$. From these results, a capacitive humidity sensor with photo sensitive polyimide is expected to be applied to a high sensitive humidity sensor.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.10
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• pp.1861-1868
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• 2008

In this paper, Passive Telemerty RF Sensor System using Unscented Kalman Filter algorithm(UKF) is proposed. General Passive Telemerty RF Sensor System means that it should be "wireless", "implantable" and "batterless". Conventional Passive Telemerty RF Sensor System adopts Integrated Circuit type, but there are defects like complexity of structure and limit of large power consumption in some cases. In order to overcome these kinds of faults, Passive Telemetry RF Sensor System based on inductive coupling principle is proposed in this paper. Because passive components R, L, C have stray parameters in the range of high frequency such as about 200[KHz] used in this paper, Passive Telemetry RF Sensor System considering stray parameters has to be derived for accurate model identification. Proposed Passive Telemetry RF Sensor System is simple because it consists of R, L and C and measures the change of environment like pressure and humidity in the type of capacitive value. This system adopted UKF algorithm for estimation of this capacitive parameter included in nonlinear system like Passive Telemetry RF Sensor System. For the purpose of obtaining learning data pairs for UKF Algorithm, Phase Difference Detector and Amplitude Detector are proposed respectively which make it possible to get amplitude and phase between input and output voltage. Finally, it is verified that capacitive parameter of proposed Passive Telemetry RF Sensor System using UKF algorithm can be estimated in noisy environment efficiently.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.1117-1118
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• 2011

• Journal of the Korean Society for Precision Engineering
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• v.22 no.6 s.171
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• pp.30-39
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• 2005

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.841-842
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• 2011

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.1103-1104
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• 2011

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2010.10a
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• pp.537-537
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• 2010

High precision sensing is very important in various technologies. Especially, it is more important when it were applied to nano/micro meter level's sensing like AFM, storage, etc. And capacitive sensing is widely used method. To improve the measurement efficiency, many signal conditioners were studied and one of them was surface acoustic wave (SAW) device. SAW device is very widely used as a high frequency bandwidth filter. Due to the reflective characteristic of high frequency, the response of SAW device contains both propagative and reflective signal at the external impedance. In this paper, we used SAW device as signal conditioner of capacitive sensor. And high precision gap measurement was executed using capacitive load. Reference signal was reflective SAW response and the magnitude at the center frequency of SAW device by the change of impedance was checked. Finally, the attainable gap resolution was determined.