• 대한전기학회논문지:전기물성ㆍ응용부문C
• /
• 제54권7호
• /
• pp.308-314
• /
• 2005

The 2 GHz film bulk acoustic wave resonator(FBAR), one of the most necessary device of the next generation mobile communication system, consisted of solidly mounted resonator(SMR) structure using Brags reflector, was researched in this paper The FBAR applied SiO$_{2}$ and W had large difference of the acoustic impedance to reflector Al to electrode and ZnO to piezoelectric layer. Specially, the FBAR applied the two-step deposition method to improve the c-axis orientation and increase reproducibility of the fabrication device had good performance. The electrical properties of plasma such as impedance, resistance, reactance, $V_{pp},\;I{pp}$, VSWR and phase difference of voltage and current, was analyzed and measured by RF sensor with the variable experiment process factors such as gas ratio, RF power and base vacuum level about concerning the thickness, c-axis orientation, adhesion and roughness. The FBAR device about the optimum condition resulted reflection loss(S$_{11}$) of -17 dB, resonance frequency of 1.93 GHz, electric-mechanical coefficient(k$_{eff}$) of 2.38 $\%$ and Qualify factor of 580. It was seen better qualify than the common dielectric filter at present and expected on business to the filter device of 2 GHz bandwidth with the MMIC technology.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2009년도 제40회 하계학술대회
• /
• pp.1539_1540
• /
• 2009

본 논문에서는 Porous Au-Pt 전극을 기반으로 연료전극과 공기전극으로 구성된 초소형 메탄올 센서를 설계 및 제작하고 그 특성을 분석해 보았다. 제안된 Porous Au-Pt 전극은 Porous 구조의 금속을 만드는 방법 중 하나인 Templating기법을 적용하여 수백나노 크기의 Pore들을 가진 Porous Au 전극을 제작하였고 그 위에 수 나노 크기의 Pt particles을 전해 도금하여 제작되었다. 고분자 전해질막 층으로서 Nafion film은 전해 도금한 Porous Au-Pt 전극 사이에 삽입하고 hot Pressing 통하여 센서를 구성하였다. Porous Au-Pt 전극을 기반으로한 전기화학 메탄올 센서는 $0.25\;cm^2$ 의 작은 전극 면적에도 불구하고 넓은 온도 범위 ($20^{\circ}C-100^{\circ}C$) 에서 온도에 따른 뛰어난 선형성(Correlation coefficient = 0.986)을 보였으며, 특히, 일정온도 ($60^{\circ}C$)에서 메탄올 농도 0 M에서 2 M 까지의 전류응답 특성을 측정, 분석 결과 메탄올 농도에 따른 9.6 mA/$mM{\cdot}cm^2$ 의 민감도 및 10 초 이내의 응답시간 특성을 보였다.

• Journal of Electrical Engineering and Technology
• /
• 제8권6호
• /
• pp.1468-1473
• /
• 2013

This paper dealt with the propagation characteristics of acoustic signals produced by partial discharges and the positioning of PD origin in insulation oil to develop insulation diagnostic techniques of oil-immerged transformers. Electrode systems such as needle to plane, plane to plane, and particle electrodes were fabricated to simulate some defects of power transformers. In addition, the frequency spectrum and propagation characteristics of acoustic signals with partial discharge (PD) in insulation oil were analyzed. Although there were differences based on the type of defect, the frequency spectra of the acoustic signals measured by wide and narrow band acoustic emission (AE) sensors were distributed in the range of 50 kHz-400 kHz. Therefore, a narrowband AE sensor is suitable for the diagnosis of oil-immersed power transformers. We could find the position of the PD source with an error margin of 10% in the experiments by calculating the position of the PD occurrence using the time difference of arrival measured by five AE sensors.

• 센서학회지
• /
• 제15권5호
• /
• pp.334-340
• /
• 2006

A compact biosignal monitoring device was developed. Electrodes for electrocardiogram (ECG) and a LED and silicon detector for photoplethysmogram (PPG) were used. A lead II type was arranged for ECG measurement and reflected light was measured at the finger tip for PPG. A single chip microprocessor (model ADuC812, Analog Device) controlled a measurement protocol and processed measured signals. PPG and ECG had a sampling rate of 300 Hz with 8-bit resolution. The maximum power consumption was 100 mW. The microprocessor computed pulse transit time (PTT) between the R-wave of ECG and the peak of PPG. To increase the resolution of PTT, analog peak detectors obtained the peaks of ECG and PPG whose interval was calculated using an internal clock cycle of 921.6 kHz. The device was designed to be operated by 3-volt battery. Biosignals can be measured for $2{\sim}3$ days continuously without the external interruptions and data is stored to an on-board memory. Our system was successfully tested with human subjects.

• 통합자연과학논문집
• /
• 제3권3호
• /
• pp.168-173
• /
• 2010

Novel porous silicon chip exhibiting dual optical properties, both Frbry-Perot fringe (optical reflectivity) and photoluminescence had been developed and used as chemical sensors. Porous silicon samples were prepared by an electrochemical etch of p-type sillicon wafer (boron-doped, <100> orientation, resistivity 1 - 10 ${\Omega}$). The ething solution was prepared by adding an equal volume of pure ethanol to an aqueous solution of HF (48% by weight). The porous silicon was illuminated with a 300 W tungsten lamp for the duration of etch. Ething was carried out as a two-electrode Kithley 2420 preocedure at an anodic current. The surface of porous silicon was characterized by FT-IR instrument. The porosity of samples was about 80%. Three different types of porous silicon, fresh porous silicon (Si-H termianated), oxidized porous silicon (Si-OH terminated), and surface-derivatized porous silicon (Si-R terminated), were prepared by the thermal oxidation and hydrosilylation. Then the samples were exposed to the wapor of various organics vapors. such as chloroform, hexane, methanol, benzene, isopropanol, and toluene. Both reflectivity and photoluminescence were simultaneously measured under the exposure of organic wapors.

• JSTS:Journal of Semiconductor Technology and Science
• /
• 제14권2호
• /
• pp.153-162
• /
• 2014

We show that carbon nanotube sensors with gold particles on the single-walled carbon nanotube (SWNT) network operate as Schottky barrier transistors, in which transistor action occurs primarily by varying the resistance of Au-SWNT junction rather than the channel conductance modulation. Transistor characteristics are calculated for the statistically simplified geometries, and the sensing mechanisms are analyzed by comparing the simulation results of the MOSFET model and Schottky junction model with the experimental data. We demonstrated that the semiconductor MOSFET effect cannot explain the experimental phenomena such as the very low limit of detection (LOD) and the logarithmic dependence of sensitivity to the DNA concentration. By building an asymmetric concentric-electrode model which consists of serially-connected segments of CNTFETs and Schottky diodes, we found that for a proper explanation of the experimental data, the work function shifts should be ~ 0.1 eV for 100 pM DNA concentration and ~ 0.4 eV for $100{\mu}M$.

• 전기화학회지
• /
• 제15권4호
• /
• pp.249-255
• /
• 2012

크레아티닌 센서의 생체시료 측정 시 가장 심각한 방해 작용을 발생하는 물질인 크레아틴을 효과적으로 제거하기 위하여 creatine kinase와 adenosine triphosphate를 사용한 두 번째 효소층을 도입하여 크레아틴에 대한 방해작용을 현저히 감소시켰다. 또한 평면형 소형 크레아티닌 센서를 개발하기 위해 탄소전극 표면에 Pt black(Pt-B)을 도입하여 표면적을 증가시킴으로써 전기화학적 감응 특성을 증가시킨 스크린 프린팅 방식의 Pt-B/C 전극을 제작하였다. 최적화된 소형 크레아티닌 센서를 흐름계 카트리지에 장착하여 미지시료를 측정한 결과 5% 이내의 오차 범위 내에서 우수한 측정 정확성과 재현성을 보임을 확인하였다.

• Transactions on Electrical and Electronic Materials
• /
• 제5권4호
• /
• pp.133-137
• /
• 2004

The development of digital x-ray detector has been extensively progressed for the application of various medical modalities. In this study, we introduce a new hybrid-type x-ray detector to improve problems of a conventional direct or indirect digital x-ray image technology, which composed of multi-layer structure using a CaWO$_4$ phosphor and amorphous selenium (a-Se) photoconductor. The leakage current of our detector was found to be ∼180 pA/cm$^2$ at 10 V/m, which was significantly reduced than that of a single a-Se detector. The x-ray sensitivity was measured as the value of 4230 pC/cm$^2$/mR at 10 V/m. We found that the parylene thin film between a CaWO$_4$ phosphor and an a-Se layer acts as an insulator to prevent charge injection from indium thin oxide (ITO) electrode into an a-Se layer under applied bias.

• 대한전자공학회논문지TE
• /
• 제42권3호
• /
• pp.19-24
• /
• 2005

본 연구에서는 일반 주택이나 저전력의 전기를 사용하는 전기환경에서 발생하는 전기 화재의 원인이 되는 아크를 검출하고 부하 전류를 차단하여 화재를 방지할 수 있는 제어기를 설계하였다. 전기 화재를 방지하기 위해 전기가 발명된 이래로 많은 변천이 있어왔다. 휴즈에서 시작하여 일반 누설전류에서 동작하는 차단기를 거쳐 아크를 검출하고 부하전류를 제어할 수 있는 장치까지 개발되기에 이르렀다. 현재 발생하는 많은 전기 화재의 원인은 아크로 인해 발생하는 것으로 확인되었다. 본 연구를 통해서 일반 전기 환경에서 발생하는 전기 화재의 원인을 미연에 검출하여 인명피해는 물론이고 물질적인 피해를 방지할 수 있도록 하였으며, 본 연구를 계속적으로 확대하여 대전력 환경에서도 안정적으로 동작할 수 있는 제어기를 설계하고자 한다.

• 한국기계가공학회지
• /
• 제19권4호
• /
• pp.65-70
• /
• 2020

While the demand for robots in the manufacturing industry has dramatically increased, the industrial robots' functionality is mainly determined by the effector attached to the end of their arms. They need a flexible gripping system that can act as a human hand and easily grasp a variety of objects, which requires resilient sensors. This study clarifies the electrical output characteristics of elastic tactile sensors according to contact terminals because the output characteristics of the tactile sensors vary greatly, depending on the contact material and the method of contact with the conductive wire. Our research considers the Three Roll Mill and Paste Mixer as the dispersion medium, and a nickel- and gold-plated brass electrode as the contact terminal.