• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.441-443
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• 2008

A non-vacuum process for fabrication of $CuInSe_2$ (CIS) absorber layer from the corresponding Cu, In solution precursors was described. Cu, In solution precursors was prepared by a room temperature colloidal route by reacting the starting materials $Cu(NO_3)_2$, $InCl_3$ and methanol. The Cu, In solution precursors were mixed with ethylcellulose as organic binder material for the rheology of the mixture to be adjusted for the doctor blade method. After depositing the mixture of Cu, In solution with binder on Mo/glass substrate, the samples were preheated on the hot plate in air to evaporate remaining solvents and to burn the organic binder material. Subsequently, the resultant CI/Mo/glass sample was selenized in Se evaporation in order to get a solar cell applicable dense CIS absorber layer. The CIS absorber layer selenized at $530^{\circ}C$ substrate temperature for 30 min with various Se gas evaporation temperature was characterized by XRD, SEM, EDS.

• Journal of the Korean Society for Nondestructive Testing
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• v.32 no.2
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• pp.122-130
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• 2012

Adhesive bend and shear tests of micro-sized bonded component have been performed to clarify the relationship between effects of heat-treatment on the adhesive strength and the bonded specimen shape using Weibull analysis. Multiple micro-sized SU-8 columns with four different diameters were fabricated on a Si substrate under the same fabrication condition. Heat-treatment can improve both of the adhesive bend and shear strength. The improvement rate of the adhesive shear strength is much larger than that of the adhesive bend strength, because the residual stress, which must change by heat-treatment, should effect more strongly on the shear loading. In case of bend type test, the adhesive bend strength in the smaller diameters (50 and $75\;{\mu}m$) widely vary, because the critical size of the natural defect (micro-crack) should vary more widely in the smaller diameters. In contrast, in case of shear type test, the adhesive shear strengths in each diameter of the columns little vary. This suggests that the size of the natural defects may not strongly influence on the adhesive shear strength. All the result suggests that both of the adhesive bend and shear strengths should be complicatedly affected by heat-treatment and the bonded columnar diameter.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.2
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• pp.115-119
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• 2016

Winding is one of the major processes in roll-to-roll systems. Taper tension profile in a winding determines the distribution of stress in the radial direction, i.e., the radial stress in the wound rolls. Maximum radial stress is major cause of material defect, and this study has been actively proceeded. Traditional models of radial stress model were focused on flexible and light substrate. In this study, we developed an advanced radial stress model including effects of both these parameters(weight and stiffness) on the radial stress. The accuracy of the developed model was verified through FEM(Finite Element Method) analysis. FEM result of maximum radial stress value corresponds to 99 % in comparison to result with the model. From this study, the material defects does not occur when the steel winding. And steel industry can be applied to improve the winding process.

• BMB Reports
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• v.30 no.2
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• pp.150-156
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• 1997

Tyrosinase was purified from Solanum melongena by ammonium sulfate precipitation, Sephadex G-150 and DEAE-Sephacel column chromatography. The molecular weight of the purified tyrosinase was approximately 88,600 daltons with 805 amino acid residues. The amino acid composition showed the characteristic high contents of glycine, glutamic acid and serine residues. The enzyme had high substrate specificity towards (+)-catechin. The $K_m$, value for L-DOPA was 20.8 mM. L-ascorbic acid, ${\beta}-mercapto-ethanol$, sodium diethyldithiocabamate, KCN and $NaN_3$ had strong inhibitory effects on enzyme activity. Sodium diethyldithiocabamate was a competitive inhibitor of the enzyme with a $K_i$ value of $5.2{\times}10^{-2}\;mM$. The optimum pH of the enzyme was 9.0 and the optimum temperature was $65^{\circ}C$ with L-DOPA as a substrate. In addition, the activity was enhanced by addition of $Ca^{+2}$ or $Cu^{+2}$, but decreased in the presence of $Fe^{2+},Fe^{3+}$ and $Zn^{2+}$ ions.

• Carbon letters
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• v.7 no.2
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• pp.105-113
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• 2006

The electro-chemical removal (ECR) of water pollutants by metal-ACF electrodes from wastewater was investigated over wide range of ECR time. The ECR capacities of metallic ACF electrodes were related to physical properties such as adsorption isotherm, surface area and pore size and to reaction time. Surface morphologies and elemental analysis for the metal supported ACFs after electro-catalytic reaction were investigated by scanning electron microscopy (SEM) and energy disperse X-ray (EDX) to explain the changes in adsorption properties. The IR spectra of metallic ACFs for the investigation of functional groups show that the electro-catalytic treatment is consequently associated with the removal of pollutants with the increasing surface reactivity of the activated carbon fibers. The metal-ACFs were electro-catalytically reacted to waste water to investigate the removal efficiency for the COD, T-N, $NH_4$-N, $NO_3$-N and $NO_2$-N. From these removal results of the piggery waste using metallic ACFs substrate, satisfactory removal performance was achieved. The removal efficiency of the metallic ACFs substrate was mainly determined by the properties of the material for adsorption and trapping of organics, and catalytic effects.

• Journal of the Korean Society of Safety
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• v.19 no.2
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• pp.41-46
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• 2004

The formation of rust on metallic substrate is known to cause the damages and destructions of raw materials, which is one of the leading reasons of sturctural collapses and many kind of hazards in modern industry. Polymer gels with rust removing effects were compounded in this study by employing various kinds of acids like hydrochloric acid, phosphoric acid, gluconic acid, oxalic acid as the rust removing ingredients. TEA(Triethanolamine) as dispersant and hydrophilic chemical were used for effective gelation of acids. Also corrosion inhibitor was added to enable the coating effect and to improve rust removing effect on metallic surface. In order to investigate the rust properites on metallic substrate, artificial rusts were prepared in salt solution, using iron, copper, aluminium and brass as the base metals. The properties of gel compounds were checked by gelation, pH, viscosity, morphology property and rust removing test. Developed gel compounds in this study have a good rust removing property, showing a strong adhesion on horizontal and vertical metallic surface, and can be easily rinsed off by water.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.7
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• pp.584-588
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• 2011

The ZnO thin films doped with Ga and Ge (GZO:Ge) were prepared on glass substrate using RF sputtering system. Structural, morphological and optical properties of the films deposited in different temperatures were studied. Proportion of the element of using target was 97 wt% ZnO, 2.5 wt% Ga and 0.5 wt% Ge with 99.99% highly purity. Structural properties of the samples deposited in different temperatures with 200 w RF power were investigated by field emission scanning electron microscopy, FE-SEM images and x-ray diffraction XRD analysis. Atomic force microscopy, AFM images were able to show the grain scales and surface roughness of each film rather clearly than SEM images. it was showed that increasing temperature have better surface smoothness by FE-SEM and AFM images. Transmittance study using UV-Vis spectrometer showed that all the samples have highly transparent in visible region (300~800 nm). In addition, it can be able to calculate bandgap energy from absorbance data obtained with transmittance. The hall resistivity, mobility, and optical band gap energy are influenced by the temperature.

• BMB Reports
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• v.33 no.4
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• pp.312-316
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• 2000

Effects of various nitrogenous compounds on the peroxidative activity of Korean radish (Rophanus sativus L.) isoperoxidase $A_1$ were examined by using anilino substrates, such as dianisidine and phenylenediamine. We also used phenolic substrates such as guaiacol, chlorogenic acid, caffeic acid, ferulic acid and esculetin. The peroxidation of dianisidine was stimulated by adenine and imidazole as much as 5 fold and 11 fold, respectively at pH 8. Moreover, about 4.8 fold and 8 fold stimulation of phenylenediamine peroxidation occurred by adenine and imidazole, respectively at pH 8. The stimulation by adenine and imidazole did not occur at the acidic pH range. The peroxidations of phenolic substrates, such as guaiacol, chlorogenic acid, caffeic acid, ferulic acid and esculetin, were not boosted greatly by any of the nitrogenous compounds tested. Notably, ammonium salt, which has been known for the excellent booster of horseradish peroxidase, did not affect the peroxidation of the Korean radish isoperoxidase $A_1$. The kinetic studies of dianisidine peroxidation with imidazole, as a model of boosting reaction, showed that neither the affinity of imidazole against dianisidine, nor the activation energy of dianisidine peroxidation changed during the activity boosting of isoperoxidase $A_1$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.6
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• pp.468-471
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• 2013

In this paper, we analyzed the effects of the number of TIPS-pentacene droplets and also the substrate temperature on the performance of OTFTs. As the number of the droplets increased, the mobility increased and reached the peak value and then reduced at the all temperatures. The peak mobility was $0.14{\pm}0.03cm^2/V{\cdot}sec$ at 3 droplets and $41^{\circ}C$, $0.19{\pm}0.02cm^2/V{\cdot}sec$ at 4 droplets and $46^{\circ}C$, and $0.35{\pm}0.10cm^2/V{\cdot}sec$ at 7 droplets and $51^{\circ}C$. The reason of existence of peak mobility can be found in matching the evaporation of solvent with the velocity of crystal formation. When two parameters were properly matched, the mobility produced the highest.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1345_1346
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• 2009

In this study, transparent and conductive Al-doped zinc oxide (AZO) films were prepared on glass substrate by RF magnetron sputtering method using an Al-doped ZnO target (Al: 2wt.%) at room temperature as the thickness of 150 nm. We investigated the effects of the RF power between 100~350 W in the steps of 50 W on structural, electrical and optical properties of AZO films. The thickness and cross-sectional images of films were observed by field emission scanning electron microscopy (FE-SEM) and all of the films were kept to be constant about 150 nm on glass substrate. The grain size of AZO films figured out X-ray diffraction (XRD) on using the Scherrer' equation and their electrical properties investigated Hall effect electronic transport measurement system. Moreover, we measured transmittance of AZO films by UV/VIS spectrometer.