• Journal of the Korean Society of Propulsion Engineers
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• v.20 no.3
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• pp.54-62
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• 2016

Micro plasma thruster (${\mu}PT$) was studied experimentally with a dual-stage micro-hollow cathode discharge (MHCD) plasma. Electrostatic-like acceleration exhibiting more directional and elongated exhaust plume was achieved by a dual layer MHCD at the total input power less than 10 W with argon flow rate of 40 sccm. V-I characteristic indicated that there was an optimal regime for dual-stage operation where the acceleration voltage across the second stage remained constant. Estimated exhaust plume length showed a similar trend to the analytic estimate of exhaust velocity which scales with an acceleration voltage. ${\mu}PT$ with multiple holes exhibited similar performance with single-hole thruster indicating that higher power loading is possible owing to decreased power through each hole. Boltzmann plot of atomic argon spectral lines showed average electron excitation temperature of about 2.6 eV (~30,170 K) in the exhaust plume.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.9
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• pp.681-684
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• 2010

The $TiO_2$/ZnS/Ag/ZnS/$TiO_2$ multilayered structure for the transparent electrodes in plasma display panel was designed by essential macleod program (EMP) and the multilayered film was deposited on a glass substrate by direct-current (DC)/radio-frequency (RF) magnetron sputtering system. During film deposition process, the Ag layer in $TiO_2$/Ag/$TiO_2$ structure became oxidized and the filter characteristic was degraded easily. In this study, ZnS layer was adopted as a diffusion blocking layer between $TiO_2$ and Ag to prevent the oxidation of Ag layer efficiently in $TiO_2$/ZnS/Ag/ZnS/$TiO_2$ structure. Based on the AES depth profiling analysis, the Ag layer was effectively protected by the ZnS layer as compared with the $TiO_2$/Ag/$TiO_2$ multilayered films without ZnS as an antioxidant layer. The 3 times stacked $TiO_2$/ZnS/Ag/ZnS/$TiO_2$ films have low sheet resistance of $1.22{\Omega}/{\square}$ and luminous transmittance was as high as 62% in the visible ranges.

• Journal of the Microelectronics and Packaging Society
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• v.13 no.1 s.38
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• pp.57-61
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• 2006

Fuel cells are direct current (DC) power generators. They generate electricity through an electrochemical process that converts the energy stored in a fuel directly into electricity. Fuel cells have many benefits, which produce no particulate matter, nitrogen or sulfur oxides. And they have few moving parts and produce little or no noise. When fueled by hydrogen, they yield only heat and water as byproducts. Their wide application can reduce our dependence on fossil fuels and foreign sources of petroleum. This paper is studied on a high efficiency power conditioning system (PCS) applied to the proton exchange membrane fuel cell (PEMFC) generation system. This paper is designed to a novel PCS circuit topology of high efficiency. Some experimental results of the proposed PCS is confirmed to the validity of the analytical results.

• Journal of the Korean Society for Heat Treatment
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• v.28 no.2
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• pp.63-67
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• 2015

$TiO_2/Ag/TiO_2$ trilayer films were deposited with radio frequency (RF) and direct current (DC) magnetron sputtering onto the glass substrate to consider the influence of Ag interlayer on the optical properties of the films. The thickness of $TiO_2$ films was kept at 24 nm, while the thickness of Ag interlayer was varied as 5, 10, 15, and 20 nm. As-deposited $TiO_2$ single layer films show the optical transmittance of 66.7% in the visible wave-length region and the optical reflectance of 16.5%, while the $TiO_2$ films with a 15 nm thick Ag interlayer show the enhanced optical transmittance of 80.2% and optical reflectance of 77.8%. The carrier concentration was also influenced by Ag interlayer. The highest carrier concentration of $1.01{\times}10^{23}cm^{-3}$ was observed for a 15 nm thick Ag interlayer in $TiO_2/Ag/TiO_2$ films. The observed result means that an optimized Ag interlayer in $TiO_2/Ag/TiO_2$ films enhanced the structural and optical properties of the films.

• Journal of Physiology & Pathology in Korean Medicine
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• v.26 no.6
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• pp.894-901
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• 2012

The effect of Sopung-tang(SPT) and trans-cranial direct current stimulation(tDCS) was investigated in photothrombotic brain infarction(PTI) rats. Sprague-Dawley 80 rats, were divided into four groups. group I was experiental control group(n=20), group II was PTI induced and oral administration of SPT(n=20), group III was PTI induced and tDCS administration(n=20) and group IV was PTI induced and SPT and tDCS administration for 28 days on stroke rats(n=20). Analysis the neurological function test, 25 point behavior functional score test, and immunohistochemistric finding of GDNF expression, and electron microscopy assessment In motor behavior test, the outcome of group IV was significantly difference than the other group, and In immunohistochemistric finding, group II, III, IV were increase GDNF expression on 28 days, In electron microscopy finding, the all groups were degenerated of cell organelles, and synaptic plasticity were improvement of group II, III, IV(especially group IV) These results suggest that, 28days application of SPT and tDCS was the motor function and histopathologic, micro-morphological improvement of motor function recovery and positive influence on synaptic plasticity.

• Journal of the Korean Chemical Society
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• v.33 no.5
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• pp.496-503
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• 1989

The chemical behavior of trivalent lanthanide (Pr(III) and Yb(III)) and 2, 2, 6, 6-tetramethyl-3, 5-heptanedione(dipivaloylmethane) complexes was investigated by the use of direct current, differential pulse polarography and cyclic voltammetry. In this study, it was founded that the reduction of trivalent lanthanide complexes was observed by one electron transfer process at Epc = -0. 13 V and -0.80 V of Pr(III), and -0.02 V of Yb(III) vs. Ag-AgCl electrode. Also, it was founded that the treatment of DP and CV to the case of a first-order chemical equilibrium reaction preceding a reversible and irreversible one electron transfer reaction, (a >0. 5) the socalled ErCr electrode process. The equilibrium constant (lnK) obtained, of various solvents, these constant were founded to be increases with decreasing dielectric constant of the solvents. Plots of lnK for these reaction against ln(l/D) for the solvents was fairly straight lines, and the behavior of the heavier lanthanides was decreased equilibrium constant with increasing atomic number.

• The Korean Journal of Pain
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• v.8 no.2
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• pp.350-353
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• 1995

The first lesion in neural tissue produced by electrical currents were made in the 19th century by workers using direct current. In 1953, Sweet and Mark clearly demonstrated that DC lesions have unpredictable and ragged borders and may vary in size. They, as well as Hunsperger and Wyss, suggested that the use of high frequency currents might provide improved results and were proved correct. However, $Bovie^{(R)}$ electrosurgical unit may also be used in percutaneous medial branch neurotomy if a lesion made at a point or the dorsal surface of the transverse process just caudal to the most medial end of the superior edge of the transverse process (Bogduk's method). At this point the medial branch lies on the bone and its depth and medial displacement are defined by the bone which precludes the need for lateral radiographs to check placement. A lesion was made at same target point using the $Bovie^{(R)}$ electrosurgical unit in a 41 year male patient who had received a Kaneda operation because of L2 compression fracture. The patient was relieved of pain without any adverse effects.

• Journal of the Korean Vacuum Society
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• v.20 no.3
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• pp.195-199
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• 2011

ITO thin films and gold (Au), copper (Cu) and nickel (Ni) intermediate ITO multilayer (ITO/Au/ITO, ITO/Cu/ITO, ITO/Ni/ITO) films were deposited on glass substrates with a reactive radio frequency and direct current magnetron sputtering system and then the effect of intermediate metal layer and annealing temperature on the methanol gas sensitivity of ITO films were investigated. Although both ITO and ITO/metal/ITO (IMI) film sensors have the same total thickness of 100 nm, IMI sensors have a sandwich structure of ITO 50 nm/metal 10 nm/ITO 40 nm. The change in the gas sensitivity of the film sensors caused by methanol gas ranging from 100 to 1000 ppm was measured at room temperature. The IAI film sensors showed the higher sensitivity than the other sensors. Finally, it is concluded that the ITO 50/Au 10/ITO 40 nm film sensors hasthe potential to be used as improved methanol gas sensor.

• Journal of the Korean institute of surface engineering
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• v.55 no.6
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• pp.363-367
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• 2022

Transparent ZnO/Ti/ZnO (ZTZ) tri-layered films were prepared with radio frequency (RF) and direct current (DC) magnetron sputtering on the glass substrate. The thickness of the ZnO and Ti films was kept at 50 and 10 nm to consider the effect of the electron irradiation on the crystallization and optoelectrical properties of the films. From the XRD spectra, post-depostion electron irradiated films showed the characteristic peaks of ZnO(002) and Ti(200), respectively. the observed grain size of the ZnO(002) and Ti(200) enlarged up to 18.27 and 12.16 nm at an irradiation condition of 750 eV. In the figure of merit which means an optoelectrical performance of the films, as deposited films show a figure of merit of 2.0×10^-5 𝛺^-1, while the films electron irradiated at 750 eV show a higher figure of merit of 5.7×10^-5 𝛺^-1.

• Journal of the Semiconductor & Display Technology
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• v.20 no.1
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• pp.32-36
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• 2021

The number of processes in the manufacture of semiconductors, displays and solar cells is increasing. And as the processes is performed, multiple layers of films and various patterns are formed on the wafer. At this time, substrate warpage occurs due to the difference in stress between each film and pattern formed on the wafer. the substrate warping phenomenon occurs due to the difference in stress between each film and pattern formed on the wafer. We developed a new warpage measurement method to measure wafer warpage during real-time processing. We performed an experiment to measure the presence and degree of warpage of the substrate in real time during the process by adding only measurement equipment for applying additional electrical signals to the existing ESC and detecting the change of the additional electric signal. The additional electrical measurement signal applied at this time is very small compared to the direct current (DC) power applied to the electrostatic chuck whit a frequency that is not generally used in the process can be selectively used. It was confirmed that the measurement of substrate warpage can be easily separated from other power sources without affecting.