• Proceedings of the KIEE Conference
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• 2000.07c
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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.

• Journal of the korean academy of Pediatric Dentistry
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• v.1 no.1
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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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• v.15 no.12
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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.

• Journal of Sensor Science and Technology
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• v.32 no.3
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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.

• Analytical Science and Technology
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• v.19 no.4
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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.

• Polymer(Korea)
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• v.36 no.2
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• pp.169-176
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• 2012

Based on our experience in developing resistive humidity sensor, interdigital gold electrodes with different fingers and gaps have been fabricated on a glass epoxy (GE) substrate using screen printing techniques. The basic structure of the electrode consisted of a 3-, 4- and 5-fingers with gaps of 310 and 460 ${\mu}m$. Gold electrode/GE was prepared by first printing silver nanopaste, followed by consecutive electroless plating of Cu, Ni and then Au. Copolymer of [2-(methacryloyloxy)ethyl] dimethyl benzyl ammonium chloride (MDBAC) and methyl methacrylate (MMA) was used as a humidity-sensing polyelectrolyte, which was fabricated by a screen printing method on the Au electrode/GE substrate. The flexible humidity sensor showed acceptable linearity between logarithmic impedance and relative humidity in the range of 20-95%RH, low hysteresis of 1.5%RH, good response and recovery time of 75 sec at 1 V, 1 kHz, and $25^{\circ}C$. Electrode construction had a significant influence on the humidity-sensing characteristics of polymeric humidity sensors. The activation energy between electrode and ion conducting polyelectrolyte plays an important role in explaining the differences of humidity sensing characteristics such as temperature dependence, sensitivity, linearity and hysteresis.

• Resources Recycling
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• v.28 no.2
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• pp.46-53
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• 2019

In this study, the extraction and reduction behavior of platinum group metals in a non-aqueous solvent based on ionic liquids was investigated in order to confirm a new extraction technology of platinum group metals. Platinum was selectively extracted using an ionic liquid $[C_4mim]PF_6$ from a mixed solution of $PdCl_2$, $PtCl_4$ and $RhCl_3$ dissolved with concentration ratio of 10:1:0.5 M. After stripping of the metals by 1 M $HNO_3$ solution, the platinum was preferentially reduced by aqueous electrolysis on gold electrode at -0.8 V (vs. Pt-QRE). The residual palladium and rhodium were transferred to ionic liquid of $[C_4mim]Cl$. The metallic palladium and rhodium could be sequentially reduced on gold and STS304 as working electrodes by non-aqueous electrolysis, respectively.

• Journal of the Korean Applied Science and Technology
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• v.33 no.3
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• pp.587-592
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• 2016

In this study, flexible acid treated single walled carbon nanotubes (A-SWCNTs) electrodes were fabricated by using gold coated PET substrate and spray coating technique. The acid-treatment method was conducted to introduce functional groups on the SWCNTs wall, which could improve dispersability of the SWCNTs and its electrochemical property. The electrochemical properties of flexible A-SWCNTs electrode were carried out by cyclic voltammetry(CV), electrochemical impedance were carried out by cyclic voltammetry(CV), electrochemical impedance spectroscopy(EIS) and galvanostatic charge/discharge (GCD) cycles. As a results, The specific capacitance value of the unbent A-SWCNTs electrode was $67F{\cdot}g^{-1}$, which decreased to $63F{\cdot}g^{-1}$ (94% retention) after 1000 GCD cycles. Interestingly, the specific capacitance of the unbent A-SWCNTs electrode with application of the 1000 GCD cycles was retained even after 500 bending to $30^{\circ}$ with 6000 GCD cycles.

• International Journal of Control, Automation, and Systems
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• v.4 no.6
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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 $3{\sim|}4V$.

• Journal of fish pathology
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• v.20 no.3
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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.