• The Transactions of the Korean Institute of Electrical Engineers C
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• v.53 no.12
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• pp.596-600
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• 2004

In this study, the surface properties of PET film were analyzed after plasma surface treatment. After plasma treatment of surface roughness and XPS were evaluated to analyze the chemical property, while the surface potential decay and surface resistance rate was measured to analyze the electric관 characteristic. When plasma discharge treatment was conducted for less than 10 minutes, the electrical insulating property was improved by evaporation of low molecular weight materials and cleaning of surface. However, when the treatment was conducted for more than 10 minutes, the insulating property was decreased due to excessive discharge energy. Analyses of chemical characteristics showed that 10-minute treatment resulted in increase of C-O and O=C-O bonds. However, when treated for more than 10 minutes. they were relatively decreased.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.8
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• pp.1083-1090
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• 1998

A kind of three-way check valve, so called hydraulic calve was proposed for the substitute of the density lock of passive reactor such as SPWR (System-Integrated Pressurized Water Reactor). The function of the valve are the separation of the borated water from main coolant loop for normal operation and the insurge of the water into the loop for shutdown and the removal of the decay power when the main coolant flow rate is not enough. To verify the operability and the characteristics of the valve, experimental works were executed with 1/3 scale model calve. Also a diffuser model was proposed for the theoretical analysis of the valve.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.10
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• pp.821-827
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• 2001

In this study performed to identify a degradation mechanism in macromolecular insulating material, the contact angel, surface potential decay, surface resistivity, and XPS analysis were compared after exposure of FRP laminate to plasma discharge. In the case of contact angle, the surface of specimen untreated showed weak hydrophobic property of 73。. However, the contact angle was decreased to 20。in the plasma-treated specimen. In the case of chemical changes arising form plasma treatment, carboxl radicals were generated mainly in the surface treated, which was rapidly changed to the hydrophilic one. In the corona potential decay study to determine the electrical changes of the surface, positive charges were rapidly decreased when compared with negative charges, leading to negative property in the surface of specimen not treated. However, in the case of the hydrophilic surface, lots of carboxl radicals acting as positive polarity were generated, resulting in positive surface. Owing to such positive surface, charges of negative polarity applied were rapidly decreased.

• Mycobiology
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• v.40 no.3
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• pp.195-201
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• 2012

During the investigation of Korean indigenous fungi from Seoul, three genera-Fuscoporia, Porostereum, and Trametopsis, and four species-Fuscoporia senex, Phlebia acerina, Porostereum spadiceum, and Trametopsis cervina were found. Their morphological characteristics were examined and their identification was confirmed by molecular analysis based on internal transcribed spacer (ITS) and nuclear large subunit ribosomal DNA region sequences. These fungi are new to Korea and registered here with descriptions.

• Journal of Sensor Science and Technology
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• v.18 no.6
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• pp.449-455
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• 2009

In this paper, we developed a digital gait analyzer using the triaxial accelerometer(TA). An approach for normal gait detection employing decay slope peak detection(DSPD) algorithm was presented. The TA was attached to the center of the waist of a subject. The subject walked a bare floor at 60, 92 and 120 steps/minute. We analyzed vertical axis acceleration signal for gait detection. At 60, 92, 120 steps/minute walking, detection accuracy of gait events were over 99 % accuracy.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2003.10a
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• pp.59-62
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• 2003

We fabricated two HTS closed coils by using resistive-joint method and the joint resistance of the coil was estimated by field decay technique at 77 K. In addition, we used the Runge-kutta method for the numerical analysis to estimate the decay properties. The joint resistances were evaluated as a function of critical current of HTS closed coil and external field strength of excitation coil. It was observed that joint resistance was independent of critical current and external field strength. It was estimated that joint resistance was 8.0$\times$10$^{-9}$ $\Omega$ to 11.9$\times$10$^{-9}$ $\Omega$ for coils of contact length for 7 cm.

• Bulletin of the Society of Naval Architects of Korea
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• v.22 no.1
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• pp.1-8
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• 1985

The buckling characteristics of cylindrical shells with a circular hole, under axially compressed loads, have been analyzed and the results have been compared with existed experimental results. Deflection function with decay factor is assumed, and stress distribution around a circular hole in tensioned infinite plate is used for formulating buckling energy function. Applying Rayleigh Ritz procedure to this energy function, characteristic equation of eigenvalue problem is determined. Buckling load is defined by the minimum value of eigenvalues calculated according to several decay factors, and as the radius ratios of a circular hole (a/R) and shell thickness ratios (R/t) are varied, the reducing characteristics of buckling load are studied. As a result, buckling loads are reduced by about 50% according to some radius ratios ($a/R{\geq}0.15$) of circular hole and are not nearly affected by shell thickness ratio(R/t).

• Korean Journal of Optics and Photonics
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• v.10 no.3
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• pp.214-220
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• 1999

We calculated the deviation of decay time owing to intensity noise of ring-down signal and the sensitivity owing to shot noise, dark current, and bit resolution error of the data acquisition device. We verified the sources of systematic errors caused by the drift of cavity loss depending on bias voltage and the oscillation of decay time caused by interfering effect of mirrors.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.5
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• pp.411-419
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• 2000

In this paper we have investigated the surface degradation by ultraviolet-irradiation in high-temperature vulcanized silicone rubber. Through the measurement of surface potential decay by corona-charging and of contact angle it is found that the change of surface electrostatic properties and the decrease of contact angle under UV-radiation. For the changes in micro-morphological and chemical structure of the UV-treated silicone rubber we utilized several analytical techniques such as SEM, ATR-FTIR,XPS. From this study it is shown that the chemical reactions(scissoring of side chain(S-$CH_3$) cross-linking and branching) occur on the surface of silicone rubber during the UV-irradiation. Also we obtained the results of the loss of low molecular weight chain by cross-linking and oxidation reaction.

• Proceedings of the KIEE Conference
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• 2002.11a
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• pp.176-178
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• 2002

Surface states of silicone polymer treated by plasma were investigated by the analysis by x-ray photoelectron spectroscopy(XPS) and surface voltage decay after corona charging. Plasma treatment causes the silica -like oxidative layer, which was confirmed with XPS, and lowers surface resistivity with increasing the plasma treatment time. Using the decay time constant of surface voltage, the calculated surface resistivity was compared with the value directly measured by voltage-current method using three electrodes system. A good agreement between two methods was obtained. In addition, we estimated the thermal activation energy for surface conduction, Based on our results, we could understand the relationship between surface chemical states and surface electrical properties.