• Journal of the Korean Crystal Growth and Crystal Technology
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• v.18 no.2
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• pp.72-75
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• 2008

Zinc oxide (ZnO) thin films were prepared by a sol-gel method. The structural and electrical properties were investigated by varying drying and annealing temperatures. The thin films were coated (250 nm) by spin-coating method on glass substrates. The optimum drying temperature of ZnO thin films was 300$^{\circ}C$ where the resistivity was the lowest and the preferred c-axis orientation was the highest. The annealing was carried out in air and inert atmospheric conditions. The degree of the preferred c-axis orientation was estimated. The highest preferred c-axis orientation was recorded at 600$^{\circ}C$. The preferred c-axis orientation and grain growth resulted in the mobility enhancement of the ZnO thin films, and the lowest resistivity was 0.62${\Omega}{\cdot}cm$ at 600$^{\circ}C$.

• Journal of the Korea Furniture Society
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• v.19 no.5
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• pp.307-318
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• 2008

Scientific methods for grading urushi lacquer includes general properties (viscosity, pH etc), and quantitative analysis of moisture, urushiol, gum, laccase content etc, and properties of coating layer such as set to touch drying time, gloss, color difference, delamination strength, tensile strength of film. The grading results evaluated by scientific method showed n order with chinese urushi lacquer (E) > domestic urushi lacquer (A) > japanese urushi lacquer (C) > chinese urushi lacquer (D) > domestic urushi lacquer (B). It is different from hose of traditional methods. Therefore, a more accurate grading of urushi lacquer should be ade by combining traditional method with scientific method.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.61-64
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• 2001

This study relates to a method for manufacturing a solid electrolytic capacitor using a functional polymer composition. The method comprises immersing the rolled aluminum electrolytic capacitor device in polyaniline solution with high electric conductivity to impregnate the device with polyaniline, drying the impregnated device in a drying oven which is maintained at constant temperature to fully remove the solvent, inserting the dried device to a capacitor aluminum can and then sealing with epoxy resin, to manufacture a solid electrolytic capacitor using a conducting polymer. As such, the impregnation can be performed well at not only normal temperature and pressure, but also high temperature and reduced pressure. The solid electrolytic capacitor has the advantages of high capacity, low impedance and low ESR, and also, low manufacturing cost, simple processes and high reliability.

• Journal of the Korean Ceramic Society
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• v.26 no.4
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• pp.532-538
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• 1989

The properties and sinterabilities of the ZrO2-3m/oY2O3 powders prepared by coprecipitation were investigated. The specific surface area and the total proe volume were decreased with the increasing pH of the sediments. The partially stabilized zirconia powders were fine powders with high specific surface area. The powders prepared by freeze drying method showed low tendency for agglomeration, and the powders obtained from spray drying method showed fine powders and narrow pore size distribution. At 140$0^{\circ}C$, their relative densities were up to 96%.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.04a
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• pp.544-550
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• 1997

In this study, the advanced on-sided stress wave velocity measurement method was applied to investigate the effects of composition, age and moisture content in concrete. Two concrete specimens that have different composition were used to figure out the change of the Longitudinal and Surface wave velocity due to different composition. The other concrete specimen was cast and the Longitudinal and Surface wave velocity was monitored during curing process. After 28-day old, the effect of moisture content in the concrete specimen to the stress wave velocity is presented in this paper during the time period 43-74 days after casting. For drying process. an aggregate drying oven was used. A conventional ultrasonic through transmission method was used to compare with the results determined by the one-sided method.

• Journal of the Korean Ceramic Society
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• v.26 no.2
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• pp.242-248
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• 1989

The powder properties and sinterability of ZrO2-8m/o Y2O3 prepared by coprecipitation were investigated. The specific surface area and the total pore volume were increased with increasing pH of sediment and using of ethyl alcohol for washing. The powders of prepared by freeze drying method were showed the smallest particle size and lowest agglomerate rate, and the powders obtained from spray drying method were showed porous structure. At 130$0^{\circ}C$, their relative density were 94-96%, so these sintered bodies have revealed high sinterability in spite of low sintering temperature.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.61-64
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• 2001

This study relates to a method for manufacturing a solid electrolytic capacitor using a functional polymer composition. The method comprises immersing the rolled aluminum electrolytic capacitor device in polyaniline solution with high electric conductivity to impregnate the device with polyaniline, drying the impregnated device in a drying oven which is maintained at constant temperature to fully remove the solvent, inserting the dried device to a capacitor aluminum can and then sealing with epoxy resin, to manufacture a solid electrolytic capacitor using a conducting polymer. As such, the impregnation can be performed well at not only normal temperature and pressure, but also high temperature and reduced pressure. The solid electrolytic capacitor has the advantages of high capacity, low impedance and low ESR, and also, low manufacturing cost, simple processes and high reliability.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.36 no.2
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• pp.39-46
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• 2004

In this paper, the effects of roll diameter and storage time in roll form, bending method and relative humidity on curl in copy paper and inkjet coated papers are investigated. In copy paper, more MD curl is showed at smaller roll diameter and the extension of bending time. However CD curl is hardly influenced by roll diameter and bending time. At high relative humidity, especially CD curl largely reduces. All inkjet coated papers without the primary or the secondary back coating during papermaking show the increase in MD curl and slight decrease in CD curl by MD bending regardless of the winding methods(TSO, TSI). The water spray as back coating results in the remarkable reduction of CD curl regardless of the winding methods. Drying on flat dryer after spraying the moisture on back side display the most excellent effect on the reduction of CD curl.

• Journal of Conservation Science
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• v.30 no.4
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• pp.467-480
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• 2014

This study was focused on measurement methods for stone cultural heritages by analyzing Ultrasonic (P-wave) velocity variations according to the water content and anisotropy of rocks. As a result of analyzing of rock properties, the water content and saturation degree were rapidly changed at the beginning of drying and then showed exponential curve which their rates of change gradually decreased. However, P-wave velocity and its rate of change maintained constant values after natural drying of 10 hours. Therefore, the ultrasonic measurement for stone cultural heritages should be performed after natural drying of 10 hours considering the weather and moisture conditions. In addition, the highest values of anisotropy coefficient exhibited in granite and limestone, and indirect method was insensitive to anisotropy compared to direct method. However, all rocks remained anisotropy by indirect method. Accordingly, ultrasonic measurement considering various directions is required. The research results will contribute to customized non-destructive testing and precise diagnosis for lithological characteristics of stone cultural heritage.

• Geomechanics and Engineering
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• v.11 no.6
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• pp.739-756
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• 2016

The shear strength reduction finite element method (SSRFEM) is a powerful tool for slope stability analysis. The factor of safety (FOS) of the slope can be easily calculated only through reducing effective cohesion (c′) and tangent of effective friction angle ($tan{\varphi}^{\prime}$) in equal proportion. However, this method may not be applicable to soil slope under wetting-drying cycles (WDCs), because the influence of WDCs on c′ and $tan{\varphi}^{\prime}$ may be different. To research the method of estimating FOS of soil slopes under WDCs, this paper presents an experimental study firstly to investigate the effects of WDCs on the parameters of shear strength and stiffness. Twelve silty clay samples were subjected to different number of WDCs and then tested with triaxial test equipment. The test results show that WDCs have a degradation effect on shear strength (${\sigma}_1-{\sigma}_3)_f$, secant modulus of elasticity ($E_s$) and c′ while little influence on ${\varphi}^{\prime}$. Hence, conventional SSRFEM which reduces c′ and $tan{\varphi}^{\prime}$ in equal proportion cannot be adopted to compute the FOS of slope under conditions of WDCs. The SSRFEM should be modified. In detail, c′ is merely reduced among shear strength parameters, and elasticity modulus is reduced correspondingly. Besides, a new approach based on sudden substantial changes in the displacement of marked nodes is proposed to identify the slope failure in SSRFEM. Finally, the modified SSRFEM is applied to compute the FOS of a slope example.