• Bulletin of the Korean Chemical Society
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• v.16 no.9
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• pp.870-873
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• 1995

A new ternary transition-metal selenide, Ta2Ni3Se8 has been synthesized from a eutectic halide flux. The structure of this phase has been characterized by single crystal X-ray diffraction techniques. The compound crystallizes in the orthorhombic system (D2h9-Pbam, a= 14.788(4) Å, b= 10.467(3) Å, c=3.4563(8) Å) with two formula units in the unit cell. This compound adopts the Nb2Pd3Se8 structure type. Hence, there are two chains of edge-sharing selenium trigonal prisms centered by tantalum atoms and these chains are interconnected through two kinds of nickel atoms. Nickel occupies both square planar and square pyramidal sites as does palladium in Nb2Pd3Se8. Electrical conductivity measurements indicate that this material is semiconducting.

• Journal of IKEEE
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• v.25 no.2
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• pp.408-411
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• 2021

This paper presents a new reflectarray antenna capable with 1-bit switchable capability for W-band beamforming network. The proposed antenna has been optimized using two unit-cells with sizes of 1.0 mm and 1.3 mm to form a total number of 193 radiating elements on a square aperture surface of length 30 mm. These radiating elements are spaced 0.5 wavelengths apart and fed by a 15 dBi pyramidal horn antenna as the feed antenna placed 53 mm away from the aperture center. The proposed reflectarray achieves a realized peak gain of 22.52 dBi, a half-power beamwidth of 5.1° in both E- and H-planes at the test frequency of 80 GHz and operates over a wide bandwidth from 74 GHz to 90 GHz.

• Transactions on Electrical and Electronic Materials
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• v.16 no.4
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• pp.212-220
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• 2015

We investigated nanotextured Si solar cells using the silver-assisted chemical etching process. The nanotexturing process is very sensitive to the concentration of chemical etching solution. The high concentration process results in a nanowire formation for the nanosurfaces and causes severe surface damage to the top region of the micropyramids. These nanowires show excellent light absorption in photoreflectance spectra and radiative light emission in photoluminescence spectra. However, the low concentration process forms a nano-roughened surface and provides high minority carrier lifetimes. The nano-roughened surfaces of the samples show the improved electrical cell properties of quantum efficiency, conversion efficiency, and cell fill factor due to the reduction in the formation of the over-doped dead layer.

• Animal cells and systems
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• v.12 no.4
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• pp.203-209
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• 2008

Berberine, an isoquinoline alkaloid found in Coptidis Rhizoma(goldenthread) extract, has multiple pharmacological effects such as anti-inflammatory, antimicrobial and anti-ischemic effects. In the present study, we examined the effects of berberine on neuronal survival and differentiation in a hippocampal precursor cell line and in the memory deficient rat model. Berberine increased in a dose dependent manner the survival of hippocampal precursor cells as well as differentiated cells. In addition, berberine promoted neuronal differentiation of hippocampal precursor cells. In the memory deficient rat model induced by stereotaxic injection of ibotenic acid into entorhinal cortex(Ibo model), hippocampal cells were increased about 2.7 fold in the pyramidal layer of CA1 region and about 2 fold in the dentate gyrus by administration of berberine after 2 weeks of ibotenic acid injection. Furthermore, neuronal cells immunoreactive to calbindin were increased in the hippocampus and entorhinal cortex area by administration of berberine. Taken together, these results suggest that berberine has neuroprotective effect in the Ibo model rat brain by promoting the neuronal survival and differentiation.

• Current Photovoltaic Research
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• v.6 no.3
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• pp.86-90
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• 2018

To generate more current in crystalline silicon solar cells, surface texturing is adopted by reducing the surface reflection. Conventionally, random pyramid texturing by the wet chemical process is used for surface texturing in crystalline silicon solar cell. To achieve higher efficiency of solar cells, well ordered inverted pyramid texturing was introduced. Although its complicated process, superior properties such as lower reflectance and recombination velocity can be achieved by optimizing the process. In this study, we investigated optical and passivation properties of inverted pyramid texture. Lifetime, implied-Voc and reflectance were measured with different width and size of the texture. Also, effects of chemical rounding at the valley of the pyramid were observed.

• 한국태양에너지학회:학술대회논문집
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• 2011.04a
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• pp.105-110
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• 2011

The doping procedure in crystalline silicon solar cell fabrication usually contains oxygen injection during drive-in process and removal of phosphorous silicate glass(PSG). In this paper, we studied the effect of oxygen injection and PSG on conversion efficiency of solar cell. The mono crystalline silicon wafers with $156{\times}156mm^2$, $200{\mu}m$, $0.5-3.0{\Omega}{\cdot}cm$ and p-type were used. After etching $7{\mu}m$ of the surface to form the pyramidal structure, the P(phosphorous) was injected into silicon wafer using diffusion furnace to make the emitter layer. After then, the silicon nitride was deposited by the PECVD with 80 nm thickness and 2.1 refractive index. The silver and aluminium electrodes for front and back sheet, respectively, were formed by screen-printing method, followed by firing in 400-425-450-550-$880^{\circ}C$ five-zone temperature conditions to make the ohmic contact. Solar cells with four different types were fabricated with/without oxygen injection and PSG removal. Solar cell that injected oxygen during the drive-in process and removed PSG after doping process showed the 17.9 % conversion efficiency which is best in this study. This solar cells showed $35.5mA/cm^2$ of the current density, 632 mV of the open circuit voltage and 79.5 % of the fill factor.

• 한국태양에너지학회:학술대회논문집
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• 2011.11a
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• pp.51-55
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• 2011

In this paper, the optimized doping condition of crystalline silicon solar cells with 156 ${\times}$ 156 mm2 area was studied. To optimize the drive-in condition in the doping process, the other conditions except drive-in temperature and time were fixed. After etching 7 ${\mu}m$ of the surface to form the pyramidal structure, the silicon nitride deposited by the PECVD had 75~80 nm thickness and 2 to 2.1 for a refractive index. The silver and aluminium electrodes for front and back sheet, respectively, were formed by screen-printing method, followed by firing in $400-425-450-550-850^{\circ}C$ five-zone temperature conditions to make the ohmic contact. Drive-in temperature was changed in range of $828^{\circ}C$ to $860^{\circ}C$ and time was from 3 min to 40 min. The sheet resistance of wafer was fixed to avoid its effect on solar cell. The solar cell fabricated with various conditions showed the similar conversion efficiency of 17.4%. This experimental result showed the drive-in temperatures and times little influence on solar cell characteristics.

• The Journal of Internal Korean Medicine
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• v.31 no.4
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• pp.763-774
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• 2010

Objectives : In condition of brain infarction, irreversible axon damage occurs in central nerve system(CNS), because gliosis becomes physical and mechanical barrier to axonal regeneration. Reactive gliosis induced by ischemic injury such as middle cerebral artery occlusion is involved with up-regulation of GFAP and CD81. The current study is to examine the effect of the Uncariae Ramulus et Uncus on CD81 and GFAP expression in the rat brain following middle cerebral artery occlusion. Methods : In order to study ischemic injuries on brain, infarction was induced by middle cerebral artery occlusion(MCAO) using insertion of a single nylon thread, through the internal carotid artery, into a middle cerebral artery. Cresyl violet staining, cerebral infarction size measurement, immunohistochemistry and microscopic examination were used to detect the expression of CD81 and GFAP and the effect on the infarct size and pyramidal cell death in the brain of the rat with cerebral infarction induced by MCAO. Results : The following results were obtained 1. Measuring the size of cerebral infartion induced by MCAO in the rat after injection of Uncariae Ramulus et Uncus showed the size was decreased. 2. Intravenous injection of Uncariae Ramulus et Uncus showed pyramidal cell death protection in the hippocampus in the MCAO rat. 3. Water extract injection of Uncariae Ramulus et Uncus decreased GFAP expression significantly in the MCAO rat. 4. Uncariae Ramulus et Uncus water extract decreased CD81 expression in the MCAO rat. 5. The administration of water extract of Uncariae Ramulus et Uncus induced up-regulation of c-Fos expression significantly compared with MCAO. 6. The admistration of water extract of Uncariae Ramulus et Uncus increased ERK expression significantly compared with MCAO. Conclusion : We observed that Uncariae Ramulus et Uncus could suppress the reactive gliosis, which disturbs the axonal regeneration in the brain of the rat with cerebral infaction after MCAO by controlling the expression of CD81 and GFAP. The effect may be modulated by the up-regulation of c-Fos and ERK. These results suggest that Uncariae Ramulus et Uncus can be a candidate to regenerate CNS injury.

• The Journal of Internal Korean Medicine
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• v.29 no.3
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• pp.629-640
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• 2008

Objective : The purpose of this study was to investigate the neuroprotective effect of Jukryuk on 4-vessel occlusion(4-VO) and middle cerebral artery (MCA) ischemia. Method : After administration of Jukryuk, we compared the Jukryuk-treated group, the control, and the sham groups, in view of several points as follows 1) We evaluated the damage characterized by coagulative cell change of pyramidal neurons and pronounced gliosis in each group 2) We counted the number of normal pyramidal shapes after ischemia in each group 3) Immunohistochemistry (cyclooxygenase-2) 4) In focal ischemic injury model, we measured the volume of ischemic area Results : In this experiment, the effect of Jukryuk was determined to be protecting neuron cell shape, reducing the number of neuron cells damaged by ischemia and the volume of the ischemic area. In immunohistochemistry, Jukryuk reduced cyclooxygenase-2 expression Conclusions : According to this study, Jukryuk can protect neuron cells from injury by cerebrovascular ischemia.

• JSTS:Journal of Semiconductor Technology and Science
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• v.12 no.1
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• pp.59-65
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• 2012

A study on the electrical characteristic analysis of solar cell diodes under experimental conditions of varying temperature and frequency has been conducted. From the current-voltage (I-V) measurements, at the room temperature, we obtained the ideality factor (n) for Space Charge Region (SCR) and Quasi-Neutral Region (QNR) of 3.02 and 1.76, respectively. Characteristics showed that the value of n (at SCR) decreases with rising temperature and n (at QNR) increases with the same conditions. These are due to not only the sharply increased SCR current flow but the activated carrier recombination in the bulk region caused by defects such as contamination, dangling bonds. In addition, from the I-V measurements implemented to confirm the junction uniformity of cells, the average current dispersion was 40.87% and 10.59% at the region of SCR and QNR, respectively. These phenomena were caused by the pyramidal textured junction structure formed to improve the light absorption on the device's front surface, and these affect to the total diode current flow. These defect and textured junction structure will be causes that solar cell diodes have non-ideal electrical characteristics compared with general p-n junction diodes. Also, through the capacitance-voltage (C-V) measurements under the frequency of 180 kHz, we confirmed that the value of built-in potential is 0.63 V.