• 센서학회지
• /
• 제32권4호
• /
• pp.219-222
• /
• 2023

Partial discharges (PD) have long been recognized as a major contributing factor to catastrophic failures in high-power equipment. As the demand for high voltage direct current (HVDC) facilities continues to rise, the significance of on-line and real-time monitoring of PD becomes increasingly prominent. In this study, we have designed, fabricated, and characterized a highly sensitive and cost-effective PD sensor comprising a pair of copper electrodes with different arc lengths. The key advantage of our sensor is its non-invasive nature, as it can be installed at any location along the entire power cable without requiring structural modifications. In contrast, conventional PD sensors are typically limited to installation at cable terminals or insulation joint boxes, often necessitating invasive alterations. Our PD sensor demonstrates exceptional accuracy in estimating PD location, with a success rate exceeding 95% in the straight sections of the power cable and surpassing 89% in curved sections. These remarkable characteristics indicate its high potential for realtime and on-line detection of PD.

• 센서학회지
• /
• 제6권6호
• /
• pp.476-482
• /
• 1997

주성분 분석 및 역전달 인공 신경망의 패턴 인식 기법과 산화물 반도체 가스센서 어레이를 사용한 소형 전자코 시스템을 제작하여 그 특성을 평가하였다. 센서 어레이로서 Pd가 첨가된 $WO_{3}$, Pt가 첨가된 $SnO_{2}$, $TiO_{2}-Sb_{2}O_{5}-Pd$가 첨가된 $SnO_{2}$, $TiO_{2}-Sb_{2}O_{5}-Pd$가 첨가된 후 Pd 코팅층이 형성된 $SnO_{2}$, $Al_{2}O_{3}$가 첨가된 ZnO 및 $PdCl_{2}$가 첨가된 $SnO_{2}$ 등의 6가지 조성의 감지재료가 사용되었다. 전자코 시스템 하드웨어는 CPU로서 16bit의 Intel 80c196kc, 시스템 동작 프로그램의 저장을 위한 EPROM, 인공 신경망의 최적화된 가중치의 다운로딩을 위한 EEPROM, 가스농도의 결과 표시를 위한 LCD 등으로 구성하였다. 시스템의 성능 평가를 위해 자동차에서 배출되는 환경오염 물질인 CO/HC 가스(CO 0%/HC 0 ppm 에서 CO 7.6%/HC 400 ppm 까지 범위의 26가지 CO/HC 혼합가스 패턴)에 대한 인식 실험 결과 우수한 특성을 얻을 수 있었다.

• 센서학회지
• /
• 제21권6호
• /
• pp.425-428
• /
• 2012

This paper presents the fabrication and characterization of graphene based hydrogen sensors. Graphene was synthesized by annealing process of Ni/3C-SiC thin films. Graphene was transferred onto oxidized Si substrates for fabrication of chemiresistive type hydrogen sensors. Au electrode on the graphene shows ohmic contact and the resistance is changed with hydrogen concentration. Nanoparticle catalysts of Pd and Pt were decorated. Response factor and response (recovery) time of hydrogen sensors based on the graphene are improved with catalysts. The response factors of pure graphene, Pt and Pd doped graphenes are 0.28, 0.6 and 1.26, respectively, at 50 ppm hydrogen concentration.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2005년도 제36회 하계학술대회 논문집 C
• /
• pp.2369-2371
• /
• 2005

MEMS 기술을 이용하여 마이크로 $H_2$ 가스센서를 제작하고 마이크로 히터의 열적 특성과 $H_2$ 가스 농도 변화에 따를 마이크로 가스센서에 대한 감도를 분석하였다. 마이크로 가스센서의 전압 인가에 따른 히터의 온도는 1.0V에서 $250-280^{\circ}C$의 고온 특성을 보였으며, 동작온도 $250^{\circ}C$에서 $H_2$ 가스는 $SnO_2/V_2O_5/Pd$의 감응물질을 도포한 센서의 반응이 우수한 특성을 확인하였다. 동작 온도 $250^{\circ}C$ $H_2$ 농도 5000ppm의 조건에서 $SnO_2/V_2O_5/Pd$의 감응물질을 도포한 가스센서에서 $H_2$ 흡착 반응 시간은 3sec이 탈착 반응 시간은 8-10sec의 결과를 보였다.

• 센서학회지
• /
• 제23권3호
• /
• pp.207-210
• /
• 2014

$TiO_2$ oxide semiconductor is being widely studied in various applications such as photocatalyst and photosensor. Pd/$TiO_2$ gas sensor is mainly used to detect $H_2$, CO and ethanol. This study focus on increasing hydrogen detection ability of Pd/$TiO_2$ in room temperature through Al-doping. Pd/$TiO_2$ was fabricated by the hydrothermal method. Contacting to Aluminum (Al) foil led to Al doping effect in Pd/$TiO_2$ by thermal diffusion and enhanced hydrogen sensing response. $TiO_2$ nanoparticles were sized at ~30 nm of diameter from scanning electron microscope (SEM) and maintained anatase crystal structure after Al doping from X-ray diffraction analysis. Presence of Al in $TiO_2$ was confirmed by X-ray photoelectron spectroscopy at 73 eV. SEM-energy dispersive spectroscopy measurement also confirmed 2 wt% Al in Pd/$TiO_2$ bulk. The gas sensing test was performed with $O_2$, $N_2$ and $H_2$ gas ambient. Pd/Al-doped $TiO_2$ did not response $O_2$ and $N_2$ gas in vacuum except $H_2$. Finally, the normalized resistance ratio ($R_{H2on}/R_{H2off}$) of Pd/Al-doped $TiO_2$ increases about 80% compared to Pd/$TiO_2$.

• 센서학회지
• /
• 제17권5호
• /
• pp.346-349
• /
• 2008

A metal-semiconductor-metal (MSM) ultraviolet (UV) photodetector (PD) is proposed as an effective UV sensing device for integration with a GaN n-channel MISFET on auto-doped p-type GaN grown on a silicon substrate. Due to the high hole barrier of the metal-p-GaN contact, the dark current density of the fabricated MSM PD was less than $3\;nA/cm^2$ at a bias of up to 5 V. Meanwhile, the UV/visible rejection ratio was 400 and the cutoff wavelength of the spectral responsivity was 365 nm. However, the UV/visible ratio was limited by the sub-bandgap response, which was attributed to defectrelated deep traps in the p-GaN layer of the MSM PD. In conclusion, an MSM PD has a high process compatibility with the n-channel GaN Schottky barrier MISFET fabrication process and epitaxy on a silicon substrate.

• 센서학회지
• /
• 제24권5호
• /
• pp.353-357
• /
• 2015

A new SPICE-compatible model for a gate/body-tied PMOSFET photodetector (GBT PD) with an overlapping control gate is presented. The proposed SPICE-compatible model of a GBT PD with an overlapping control gate makes it possible to control the photocurrent. Research into GBT PD modeling was proposed previously. However, the analysis and simulation of GBT PDs is not lacking. This SPICE model concurs with the measurement results, and it is simpler than previous models. The general GBT PD model is a hybrid device composed of a MOSFET, a lateral bipolar junction transistor (BJT), and a vertical BJT. Conventional SPICE models are based on complete depletion approximation, which is more applicable to reverse-biased p-n junctions; therefore, they are not appropriate for simulating circuits that are implemented with a GBT PD with an overlapping control gate. The GBT PD with an overlapping control gate can control the sensitivity of the photodetector. The proposed sensor is fabricated using a $0.35{\mu}m$ two-poly, four-metal standard complementary MOS (CMOS) process, and its characteristics are evaluated.

• 전자공학회논문지
• /
• 제54권1호
• /
• pp.157-163
• /
• 2017

본 논문은 주파수대역검출센서(FBDS)를 이용하여 전력 케이블에서 부분방전(PD)가 발생했을 때 이것을 검출하고 진단하는 시스템 개발에 관한 논문이다. 주파수대역검출센서는 각 주파수대역에서 발생하는 부분방전을 음향학적으로 변환하여 검출한다. 부분방전은 그 음향학적 신호 형태로 잡음과 유사하다. 따라서 본 논문에서 상대적 레벨교차율(RLCR)과 주파수에너지 스펙트럼을 이용하여 정상과 비정상을 구별하여 부분방전을 검출하였다.

• 센서학회지
• /
• 제5권5호
• /
• pp.39-46
• /
• 1996

$WO_{3}$에 미량의 Pd 또는 Pt가 첨가된 박막을 이용한 NOx 센서를 제조하였다. $WO_{3}$계 박막은 고진공, 저항가연식 evaporator를 이용하여 분위기온도에서 증착한 다음 $500^{\circ}C$에서 열처리하였다. 5 ppm의 $NO_{2}$가스에 대하여 $200^{\circ}C$에서 측정한 가스감도($R_{gas}/R_{air}$)는 0.5 wt.% $Pt-WO_{3}$ 센서에서 50으로서 최대값을 가졌다.

• 센서학회지
• /
• 제31권6호
• /
• pp.397-402
• /
• 2022

In this short review, we explore the recent progress in metal-based gas-sensing techniques. The strong interaction between the metal films and hydrogen gas can be considered to play a considerably important role in the gas-sensing technique. The physical and chemical reactions in Pd-Pd hydride systems were studied in terms of the phase transition and lattice expansion of the metals. Two types of represented detection, electrical and optical, were introduced and discussed along with their advantages.