• Journal of Sensor Science and Technology
• /
• v.11 no.3
• /
• pp.183-190
• /
• 2002

Photoluminescence(PL) properties of $Si^+$-implanted $SiO_2$ film, which was thermally grown on c-Si substrate, is reported. We have compared room temperature photoluminescence (PL) spectra of the samples which was made in several kinds of implantation, subsequent annealing and $SiO_2$ film thickness. XRD data was correlated with the PL spectra. Silicon nanocrystals in $SiO_2$ film is considered as the origin of the photoluminescence. PL spectra was investigated after wet etching of the $SiO_2$ film by using BOE (Buffered Oxide Etchant) at every one minute. PL peak wavelength was varied as the etching is proceeded. These results indicate that the quantity and the distribution of dominant size of Si nanocrystals in $SiO_2$ film seem to have a direct effect on PL spectrum.

• Analytical Science and Technology
• /
• v.26 no.1
• /
• pp.42-50
• /
• 2013

This paper describes the electrocatalytic activity for the oxidation of small biomolecules on the surface of Pt-Ru nanoparticles supported by $TiO_2$-hollow sphere prepared for use in sensor applications or fuel cells. The $TiO_2$-hollow sphere supports were first prepared by sol-gel reaction of titanium tetraisopropoxide with poly(styrene-co-vinylphenylboronic acid), PSB used as a template. Pt-Ru nanoparticles were then deposited by chemical reduction of the $Pt^{4+}$ and $Ru^{3+}$ ions onto $TiO_2$-hollow sphere ($Pt-Ru@TiO_2-H$). The prepared $Pt-Ru@TiO_2-H$ nanocomposites were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), and elemental analysis. The electrocatalytic efficiency of Pt-Ru nanoparticles was evaluated via ethanol, methanol, dopamine, ascorbic acid, formalin, and glucose oxidation. The cyclic voltammograms (CV) obtained during the oxidation studies revealed that the $Pt-Ru@TiO_2-H$ nanocomposites showed high electrocatalytic activity for the oxidation of biomolecules. As a result, the prepared Pt-Ru catalysts doped onto $TiO_2$-H sphere nanocomposites supports can be used for non-enzymatic biosensor or fuel cell anode electrode.

• Korean Journal of Materials Research
• /
• v.12 no.4
• /
• pp.269-273
• /
• 2002

The NASICON solid electrolyte films, $Na_{1+x}Zr_2Si_xP_{3-x}O_{12}$(1.5< x < 2.3), was prepared from ceramic slurry by modified doctor-blade process. The NASICON solid electrolyte and fabricated sensors, Pt-electrode/NASICON/Carbonate$(Na_2CO_3-K_2CO_3CaCO_3\; system)$ electrode, were investigated to measure phase, microstructure and e.m.f variation for sensing $CO_2$ concentration. The uniform grain size of $2-4{\mu}m$ and major phase of sodium zirconium silicon phosphate phase, $Na_{1+x}Zr_2Si_xP_{3-x}O_{12}$was identified with X-ray diffraction patterns and scanning electron microscopy, respectively. The Nernst's slope of 84 mV/decade for $CO_2$ concentration from 500 to 8000 ppm was obtained at operating temperature of $400^{\circ}C$.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2012.08a
• /
• pp.99-99
• /
• 2012

본 개발에서는 초고속복합분자펌프 구동을 위한 디지털 구동장치를 설계하였다. BLDC구동을 위한 디지털 제어 시스템의 핵심제어 보드 설계 및 모듈 설계를 하여 보드제작 및 기본성능평가를 하고 고속 회전 실험을 하였다. AMB제어기는 넓은 제어대역폭을 확보하기 위하여 FPGA 1개와 마이크로 콘트롤러 2개를 사용하여 구성하였으며 FPGA로 AMB구동을 위한 PWM기능과 CPU 2개의 원활한 Data 통신을 위하여 Dual Memory을 구현하였으며 PWM의 디지털노이즈 회피를 위하여 AMB구동용 PWM과 동기화하여 Gap Sensor 및 전류센서신호 샘플링할 수 있도록 ADC를 구동 및 샘플링한다. 그리고 Gap Sensor 구동 회로와 제어기회로를 하나의 보드로 구연하였다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.11 no.11
• /
• pp.996-1000
• /
• 1998

This paper describes the characteristics of Pt microheater using aluminum oxide films as medium layer and its application to flow sensors. Pt microheater have heating temperature of $390^{\circ}C$ at heating power of 1.2 W. Output voltages of flow sensors which were fabricated by integrating sensing-part with heating-part increase as gas flow rate and its conductivity increase. At $O_2$ flow rate of 2000 sccm, heating power of 0.8 W, output voltage of flow sensor is 101 mV under bridge-applied voltage of 5 V.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2002.07b
• /
• pp.711-714
• /
• 2002

촉매 구조에 따른 반도체식 가스센서의 가스 감지 특성이 고찰되었다. 촉매로는 Pd를 사용하였고, 0.5 ~ 10wt% 의 다양한 농도로 약 15nm 크기의 $SnO_2$ 분말에 도핑, 가스센서를 제작하였다. 또한 열처리 온도를 $500{\sim}600^{\circ}C$로 다르게 하여 각 촉매 구조에 따른 특성의 변화를 관찰하였다. 그 결과 가스 감지 특성은 열처리 온도가 높을수록 감지 특성이 향상되었고, Pd 농도가 5wt% 에서 감도가 0.65로 좋은 감지 특성을 나타내었다. 5wt% Pd가 도핑된 가스센서는 2시간 동안 $400^{\circ}C$에서 aging 후에도 감도 값이 안정된 우수한 특성을 나타내었다.

• Proceedings of the KWS Conference
• /
• 2009.11a
• /
• pp.235-238
• /
• 2009

To study the relationship between spark ignition and the gap in the nano-scale region, the electric potential was applied to between a Pt-Ir tip and a gold substrate. The tip was sharpened by electro-chemical etching process in the solution of $CaCl_2;H_2O$ and acetone. The radius of tip was measured to be around 200nm and attached to the scanning probe microscope to control the gap between the tip and the substrate. The electric potential of 10V to 80V was applied to initialize the spark. The gaps and the current profile were measured to analyze the characteristics of spark ignition. A spark sustaining time was measured to be between 50ns and 200ns depending on the applied electric potential and the gap between the electrodes. The continuous electric discharge was successfully sustained up to 1 second of spark or arc time. The developed process can be applicable to the micro-scale fabrication of automotive sensors as a similar concept of GTAW.

• Proceedings of the Korean Powder Metallurgy Institute Conference
• /
• 2006.09a
• /
• pp.416-417
• /
• 2006

Nanostructured ceria powder was synthesized by a thermochemical process and investigated its applicability for an oxygen gas sensor. An amorphous precursor powders prepared by spray drying a cerium-nitrate solution were transformed successfully into nanostructured ceria by heat-treatment in air atmosphere. The powders were a loose agglomerated structure with extremely fine $CeO_2$ particles about 15 nm in size, resulting in a very high specific surface area $(110\;m^2/g)$. The oxygen sensitivity and the response time $t_{90}$ measured at sintered sample at $1000^{\circ}C$ was about -0.25 and very short, i.e., $3{\sim}5$ seconds, respectively.

• Proceedings of the Acoustical Society of Korea Conference
• /
• spring
• /
• pp.275-278
• /
• 2000

In this study, the acoustic transducer of a thin circular disc-type with PZT/Metal was designed. The dielectric and piezoelectric properties of $0.5wt\%$ $MnO_2$ and NiO doped 0.1Pb($Mg_{1/3}$$Nb_{2/3}$)$O_3$-$0.45PbTiO_3$-$0.45PbZrO_3$ ceramics were investigated aiming at acoustic transducer applications. The vibration characteristics for the laminated circular plate was analyzed for the various thickness and diameter of the piezoceramic layer and metal layer. The acoustic characteristics which is radiated from the acoustic transducer within the finite space was simulated using the finite element method. It has been observed that the characteristics of the sound pressure ard impedance response calculated for the various models of the size and geometry of acoustic transducer.

• Journal of Sensor Science and Technology
• /
• v.22 no.5
• /
• pp.327-332
• /
• 2013

Nickel oxide films using RF sputter was formed on the $SiO_2/Si$ substrate at the room temperature controlled with water circulation system. The feasibility of nickel oxide film as a bolometric material was demonstrated. GIXRD spectrum on NiO(111), NiO(200), and NiO(220) orientation expected as the main peaks were appeared in the grown nickel oxide films. The typical resistivity acquired at the RF power of 100W was about $34.25{\Omega}{\cdot}cm$. And it was reduced to $18.65{\Omega}{\cdot}cm$ according to the increase of the RF power to 400W. The TCR of fabricated micro-bolometer with the resistivity of $34.25{\Omega}{\cdot}cm$ was $-2.01%/^{\circ}C$. The characteristics of fabricated nickel oxide film and micro-bolometer were analyzed with XRD pattern, resistivity, TCR, and SEM images.