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윤동현,권철한,홍형기,김승렬,이규정 ( Dong Hyun Yun,Chul Han Kwon,Hyung Ki Hong,Seung Ryeol Kim,Kyu Chung Lee ) 한국센서학회 1997 센서학회지 Vol.6 No.6
An ammonia gas sensor with high sensitivity using thick-film technology were fabricated and examined. The material for sensing the ammonia gas was the mixture of oxide semiconductor, FeO_x-WO₃-SnO₂. The sensor exhibits resistance increase upon exposure to low concentration of ammonia gas. The resistance of the sensor is decreased, on the other hand, for exposure to reducing gases such as ethyl alcohol, methane, propane and carbon monoxide. A novel method for detecting ammonia gas quite selectively utilizing a sensor array consisting of an ammonia gas sensor and a compensation element were proposed and developed. The compensation element is a Pt-doped WO₃-SnO₂ gas sensor which shows opposite direction of resistance change in comparison with that of the ammonia gas sensor upon exposure to ammonia gas. Excellent selectivity has been achieved using the sensor array having two sensing elements.
윤동현(Dong-Hyun Yun),신동열(Dong-Yeol Shin),차한주(Han-Ju Cha) 대한전기학회 2015 전기학회논문지 Vol.64 No.11
Ferroresonance is a non-linear vibrational phenomenon that is generated by the electrical interaction of the inductance component with the capacitor component of a certain capacitance as the device of the inductance component such as a transformer is saturated due to the degradation, the waveform distortion of current and voltage, and the oscillation of overcurrent and overvoltage in a system. Recently, ferroresonance was generated from the waveform distortion of current and voltage, or the overvoltage or undervoltage phenomenon caused by the nature of an electrical power system and design technology of the transformer in the three phase transformer system. Hence, in general, ferroresonance analyzed by converting to the LC equivalent circuit. However, in general, the aforementioned analytical method only applies to the resonance phenomenon that is generated by the interaction of the capacitance of bussbar and grounding, and switching as the capacitor component with PT and the transformer as the inductance component in a system. Subsequently, the condition where ferroresonance was generated since overvoltage was supplied as line voltage to the phase voltage and thus the iron core is saturated due to the interconnection between grounded and ungrounded systems could not be analyzed when single phase PT was connected in a △/Y connection system. In this study, voltage swell in the configuration of grounded circuit of a step-up transformer with the △-△ connection linked to PT for control power and the ferroresonance generated by overvoltage when the line voltage of the △-△ connection was connected to the phase voltage of the grounded Y-Y connection were analyzed using PSCAD / EMTDC through the failure case of the transformer caused by ferroresonance in the system with the △-△/Y-Y connection, and subsequently, the preventive measure of ferroresonance was proposed.
박현수,윤동현,홍형기,신현우,권철한,이규정 경북대학교 센서기술연구소 1995 센서技術學術大會論文集 Vol.6 No.1
Micro gas sensor array which has four sensing layers has been made using microfabrication and micromachining techniques. The sensing materials of 6 wt% Al_(2)O_(3)-doped ZnO, 1 wt% Pd-doped SnO_(2), ZnO and WO_(3) were used for the gas sensor array whose power consumption was only 60 mW at the operating temperature of 300℃. The sensors exhibited resistance changes usable for subsquent data prosessing upon exposure to various gases and the sensitivity strongly depended on the sensing layer materials. Baseline resistances of four sensing materials were found to be stable after the aging for 3 days at 300℃.
산화물 반도체 가스 센서 어레이와 패턴 인식기술을 이용한 가스 인식
홍형기,윤동현,권철한,박현수,신현우,이규정 경북대학교 센서기술연구소 1994 센서技術學術大會論文集 Vol.5 No.1
In order to identify C_(2)H_(5)OH, (CH_(3))_(3)N and CH_(3)SH gases, a gas recognition system using gas sensor array and pattern recognition technique has been fabricated. The sensor array consists of four thick film oxide semiconductor gas sensors whose sensing layers are Pt-doped SnO_(2), Pd-doped SnO_(2), Pd-doped ZnO and Pd-doped WO_(3). Three kinds of pattern recognition techniques such as principal component analysis (PCA), discrimination analysis (DA) and back propagation (BP) were used for the discrimination of gas species. The identification of C_(2)H_(5)OH, (CH_(3))_(3)N and CH_(3)SH gases has been successfully demonstrated.