• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 C
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• pp.2230-2232
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• 2000

This paper reports an electrostatically driven and electromagnetically sensed planar vibratory gyroscope based on a surface-bulk combined micromachining. The fabricated structure has comb electrodes which are 400${\mu}m$ thick, 18${\mu}m$ wide, 600${\mu}m$ long and separated by 7${\mu}m$ so that the height-gap ratio is about 57. It also has electroplated gold springs which are 15${\mu}m$ wide, 14${\mu}m$ thick and 500${\mu}m$ long on both sides of the seismic mass. The open-loop characteristics of fabricated gyroscope at atmospheric pressure are measured on a rate table. The fabricated gyroscope has a sensitivity of 30mV/deg/sec, and a resolution of 0.1deg/sec at atmospheric pressure. It is expected that non linearity of full scale output is less than 0.8% with. the dynamic range of $\pm$500deg/sec.

• 대한소아치과학회지
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• 제1권1호
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• pp.49-55
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• 1974

Electromyographic studies were performed on the action of the masseter muscles. Among the children aged from 6 to 8 years, ten children with normal occlusion and another ten with space maintainer were selected. The children were divided into 3 groups. They were: 1) A group: Children who removed space maintainer 2) B group: Children who inserted space maintainer 3) C group: Children with normal occlusion. The electromyogram was recorded with 4 channel polygraph. (Grass model VII) Electrodes which were cup-typed gold disks, 9 millimeters in the diameter, were located on the superficial layer of masseter muscles. The electromyogram was recorded in the physiologic rest position, molar occlusion, chewing movement, protraction, left lateral movement, and right lateral movement. The conclusions were as follows. 1. In the physiologic rest position, lateral movement, the electrical potentials of the masseter muscles were not changed clearly in each groups. 2. In molar occlusion, chewing movement, The electrical potentials of the masseter muscles of the B group were almost 10% higher than those of A group, and were almost 60-70% in comparision with C group. 3. In protraction, the electrical potentials of the masseter muscles of the B group were almost 40% higher than those of A group, and were almost equal to C group. 4. The electrical activities of the masseter muscles in the mandibular movements were in the following order: (1) Molar occlusion (2) Chewing movement (3) Protraction (4) Lateral movement.

• Bulletin of the Korean Chemical Society
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• 제15권12호
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• pp.1042-1045
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• 1994

A thin film of silver ferricyanide (Ag$_3$Fe(CN)$_6$) on a platinum or gold substrates can be reduced electrochemically to the salt of silver ferrocyanide in potassium nitrate solution. The color of these films are orange and these films are shown to be electrochromic. The voltammogram is shown the asymmetry of the oxidation compared to the reduction wave under various supporting electrolytes. The standard heterogeneous electron-transfer rate for these films and bare Pt electrode were 0.49 ${\times}$ l0$^{-2}$ and 1.30 ${\times}$ l0$^{-2}$ cm/s, respectively, obtained using a rotating disc electrode. Rough D$_0$ values, evaluated from the Levich equation, for Fe(CN)$_6^{3-/4-}$ at both SF thin film and a bare Pt disc electrode were shown as 1.2l ${\times}$ l0-6 and 0.94 ${\times}$ l0$^{-6}$ cm$^2$/s, respectively. The conductivities, as determined from the slops of the i-V curves for a ca. 1 mm sample for dried SF potassium rich and deficient bulk samples pressed between graphite electrodes, were 9.34 ${\times}$ l0$^{-9}$ and 5.80 ${\times}$ l0$^{-9}$ (${\Omega}$${\cdot}$cm)$^{-1}$, respectively.

• 센서학회지
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• 제32권3호
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• pp.147-153
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• 2023

Metal-organic frameworks (MOFs) of cobalt gallate were synthesized and deposited on gold electrodes using self-assembly monolayers (SAMs) and hydrothermal processing. These MOF films exhibit strong adsorption capabilities for gaseous particulates, and the use of SAMs allows the synthesis and deposition processes to be completed in a single step. When cobalt gallate is mixed with SAMs, a coordination bond is formed between the cobalt ion and the carboxylate or hydroxyl groups of the SAMs, particularly under hydrothermal conditions. Additionally, the quartz crystal microbalance (QCM) gas sensor accurately measures the number of particulates adsorbed on the MOF films in real-time. Thus, the QCM gas sensor is a valuable tool for quantitatively measuring gases, such as SO₂, NO₂, and CO₂. Furthermore, the QCM MOF film gas sensor was more effective for gas adsorption than the MOF particles alone and allowed the accurate modeling of gas adsorption. Moreover, the QCM MOF films accurately detect the adsorption-desorption mechanisms of SO₂ and NO₂, which exist as gaseous particulate matter, at specific gas concentrations.

• 분석과학
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• 제19권4호
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• pp.333-341
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• 2006

PVP-protected Ag, Pd and $Pt_{50}-Ru_{50}$ colloids were prepared independently by using ${\gamma}$-irradiation and electron beam (EB) at ambient temperature. UV-visible spectra of these colloids show the characteristic bands of surface resonance and give evidence for the formation of nanoparticles. Transmission electron microscopy (TEM) experiments were used to know the morphology of nanoparticles prepared by ${\gamma}$-irradiation and EB. The size of Ag, Pd, and $Pt_{50}-Ru_{50}$ nanoparticles prepared by ${\gamma}$-irradiation was ca. 13, 2-3, 15 nm, respectively. While, the size of Ag, Pd, and $Pt_{50}-Ru_{50}$ nanoparticles prepared by EB was ca. 10, 6, and 1-3 nm, respectively. Cyclic voltamograms (CV) were recorded for the Au electrodes immobilized with these nanoparticles. CVs indicated the modifications in the surface as a result of immobilization.

• 폴리머
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• 제36권2호
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• pp.169-176
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• 2012

저항형 습도센서의 개발을 위하여 스크린 인쇄방법으로 glass epoxy(GE) 기재 위에 핑거의 수와 그 사이의 간격이 다른 여러 가지 바이트형의 금 전극을 제조하였다. 전극의 기본적인 구조는 핑거 수가 3, 4 및 5를 가지며 간격은 각각 310과 460 ${\mu}m$이다. 전극은 처음에 은 나노 페이스트로 전극 패턴을 인쇄하고 연속적으로 Cu, Ni 및 Au를 무전해 도금을 진행하여 제조하였다. 감습성 고분자 전해질은 [2-(methacryloyloxy)ethyl] dimethyl benzyl ammonium chloride(MDBAC)과 methyl methacrylate(MMA)의 공중합체를 사용하였으며 스크린 인쇄 방법으로 Au 전극/GE 기재 위에 인쇄하였다. 이렇게 제조된 습도 센서의 20-95%RH 영역의 상대습도 대 로그 임피던스 그래프에서 좋은 직선성을 보여주었으며 히스테리시스는 1.5%RH 이하 및 75초의 응답 및 회복 속도를 보여주었다. 전극의 구조는 고분자 저항형 습도센서의 감습특성에 큰 영향을 미치며 전해질 고분자와 전극 사이의 활성화 에너지, 온도의존성, 감도, 직선성 및 히스테리시스와 같은 감습특성 등의 차이를 비교하였고 특히 이온의 이동에 관여하는 활성화 에너지 및 온도 의존성에 큰 영향을 미쳤다.

• 자원리싸이클링
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• 제28권2호
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• pp.46-53
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• 2019

본 연구에서는 백금족 금속의 분리회수 가능성을 알아보기 위해 백금족 금속 혼합물로부터 이온성액체 기반의 용매에서 백금족 금속의 추출과 전해 환원거동을 조사하였다. 촉매조성인 10:1:0.5 M의 비로 $PdCl_2$, $PtCl_4$, $RhCl_3$가 용해되어 있는 혼합액으로부터 이온성액체인 $[C_4mim]PF_6$를 이용하여 백금(Pt)을 선택적으로 추출한 후 수계 전해액인 1 M $HNO_3$으로 역추출하고 -0.8 V (vs. Pt-QRE)의 전압과 금을 작동전극으로 사용하여 백금을 우선적으로 회수하였다. 잔류하는 팔라듐과 로듐은 $[C_4mim]Cl$ 용액으로 추출한 다음 비수계 전해법으로 환원회수하였다. 전극물질과 전압에 따른 두 금속의 환원거동을 조사하였으며, 작동전극을 탄소, 금과 STS304를 이용하여 각각 팔라듐과 로듐을 순차적으로 회수할 수 있었다.

• 한국응용과학기술학회지
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• 제33권3호
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• pp.587-592
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• 2016

본 연구에서는 유연성을 갖는 전극 제조를 위해 산 처리된 단일벽 탄소나노튜브 (Acid treated-SWCNTs)를 금이 코팅된 PET 기판 위에 스프레이 코팅하였다. 단일벽 탄소나노튜브가 가지는 단점을 보완하기 위하여 산 처리 공정을 이용하여 나노튜브에 작용기를 도입하여 분산성을 극대화 시켰으며 전기화학적 특성을 향상 시켰다. 스프레이 기술을 이용하여 제조된 유연성을 갖는 단일벽 탄소나노튜브 기반의 전극을 1 M의 황산 전해질에서 순환 전압 전류법, 임피던스 분광법 그리고 충 방전 시험을 통하여 전기화학적 특성을 분석 하였다. 그 결과, 응력을 가하지 않은 전극의 전기 용량값은 $67F{\cdot}g^{-1}$로 측정 되었으며, 1000번의 충 방전 시험 후에는 전기 용량값이 $63F{\cdot}g^{-1}$ (94 % 유지)로 감소하는 결과를 보였다. 이에 반하여, 탄소나노튜브 기반의 플렉시블 전극은 500번의 굽힘 시험 (bending test)과 6000번의 충 방전 시험 후에는 초기의 전기 용량값 ($67F{\cdot}g^{-1}$)이 유지되는 결과를 얻었다.

• International Journal of Control, Automation, and Systems
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• 제4권6호
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• pp.748-755
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• 2006

In this paper, a trade-off design and fabrication of IPMC(Ionic Polymer Metal Composites) as an actuator for a flapping device have been described. Experiments for the internal solvent loss of IPMCs have been conducted for various combinations of cation and solvent in order to find out the best combination of cation and solvent for minimal solvent loss and higher actuation force. From the experiments, it was found that IPMCs with heavy water as their solvent could operate longer. Relations between length/thickness and tip force of IPMCs were also quantitatively identified for the actuator design from the tip force measurement of 200, 400, 640, and $800{\mu}m$ thick IPMCs. All IPMCs thicker than $200{\mu}m$ were processed by casting $Nafion^{TM}$ solution. The shorter and thicker IPMCs tended to generate higher actuation force but lower actuation displacement. To improve surface conductivity and to minimize solvent evaporation due to electrically heated electrodes, gold was sputtered on both surfaces of the cast IPMCs by the Physical Vapor Deposition(PVD) process. For amplification of a short IPMC's small actuation displacement to a large flapping motion, a rack-and-pinion type hinge was used in the flapping device. An insect wing was attached to the IPMC flapping mechanism for its flapping test. In this test, the wing flapping device using the $800{\mu}m$ thick IPMC. could create around $10^{\circ}{\sim}85^{\circ}$ flapping angles and $0.5{\sim}15Hz$ flapping frequencies by applying $3{\sim|}4V$.

• 한국어병학회지
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• 제20권3호
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• pp.307-313
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• 2007

In this study, a QCM biosensor was made to detect Edwardsiella tarda (E. tarda) using a specific antibody. A 9 MHz AT-cut piezoelectric wafer layered with two gold electrodes of 5mm diameter had a reproducibility of 0.1 Hz in frequency response and was used as the transducer of the QCM biosensor. Self assembled layer (SAM) was conformed on a quartz crystal by treating with 3-mer-captopropionic acid (MPA) and activated with N-ethyl-N'-(3-dimethyl-aminopropyl) carbodiimide (EDC) and N-hydroxysuccinimide (NHS). The resulting NHS group was further converted to hydrazide by the reaction with hydrazine. Aldehyde group was introduced into the carbohydrate moiety of anti-E. tarda antibody by the reaction with periodic acid and was used to immobilise the antibody through the reaction with hydrazide group on the electrode surface. A baseline was established in the presence of phosphate-buffered saline (PBS) and a resonant frequency (F1) was measured. Sample was added to the sensor surface and second resonant frequency (F2) was measured after unbound substances were washed out with PBS several times. Finally, the frequency shift (ΔF) representing the mass change was calculated by subtracting F2 from F1. After adding the oxidized anti-E. tarda antibody to the electrode surface containing hydrazide group, frequency shift of 288.811.4 Hz (mean S.E) was observed, thus proving that considerable amount of antibody was immobilized. In the immunoassay test, the frequency shift of 1877.75 Hz, 580.67 Hz, 221.39 Hz, 7.671.83 Hz (mean S.E) were observed at doses of 1000, 500, 100, 50 g of bacterial cells, respectively. It was also demonstrated that the prepared sensor chip was stable enough to withstand repeated surface regeneration with 0.2 M Tris-glycine and 1 % DMSO, pH 2.3 more than ten times.