• Journal of Korean Society for Atmospheric Environment
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• v.5 no.2
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• pp.12-20
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• 1989

Distribution of benzo(a)pyrene (BaP) in Seoul surface soils was investigated with a simple micro-analytical method consisting of ultrasonic extraction, one-dimensional dual band thin-layer chromatographic separation (TLC) and spectrofluorometric determination. The TLC was done in the following condition: thin-layer plate; Kieselguhr G/Acetylated cellulose, Developer; 1st; ether, 2nd; methanol-ether-water (4:4:1, V/V). The results thus obtained were as follows; 1. All the samples collected from various areas were contained detectable amount of benzo(a)pyrene. The range and average of benzo(a)pyrene contents in Seoul areas are 0.20 $\sim$5.90ppm and 1.01 ppm, respectively. 2. Benzo(a)pyrene contents in soils obtained from commercial areas were much higher than those in industrial and residential areas. The contents range in commercial, industrial, and residential areas are 0.31 $\sim$ 5.90 ppm, 0.36 $\sim$ 1.22 ppm and 0.20 $\sim$ 0.67 ppm, respectively. 3. Benzo(a)pyrene contents in soils from major roads were far higher than those from side or park roads. The ranges of benzo(a)pyrene contents in major, park and side road are 0.40 $\sim$ 5.9 ppm, 0.20 $\sim$ 0.70 ppm, 0.31 $\sim$ 1.30 ppm, respectively. These findings suggest strongly that surface soils in Seoul city are polluted by benzo(a)pyrene probably emitted automobiles.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1572-1577
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• 2003

High-power pulsed laser ablation under atmospheric pressure is studied utilizing numerical and experimental methods with emphasis on recondensation ratio, and the dynamics of the laser induced vapor flow. In the numerical calculation, the temperature pressure, density and vaporization flux on a solid substrate are first obtained by a heat-transfer computation code based on the enthalpy method, and then the plume dynamics is calculated by using a commercial CFD package. To confirm the computation results, the probe beam deflection technique was utilized for measuring the propagation of a laser induced shock wave. Discontinuities of properties and velocity over the Knudsen layer were investigated. Related with the analysis of the jump condition, the effect of the recondesation ratio on the plume dynamics was examined by comparing the pressure, density, and mass fraction of ablated aluminum vapor. To consider the effect of mass transfer between the ablation plume and air, unlike the most previous investigations, the equation of species conservation is simultaneously solved with the Euler equations. Therefore the numerical model computes not only the propagation of the shock front but also the distribution of the aluminum vapor. To our knowledge, this is the first work that employed a commercial CFD code in the calculation of pulsed ablation phenomena.

• Journal of Applied Reliability
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• v.17 no.1
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• pp.78-82
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• 2017

Purpose: The purpose of this study is to evaluate failure characteristic and mechanism of four commercial water-repellent coatings for elevated temperature machinery applications. Method: Thermal degradation was performed for up to 64 thermal cycles. 1 cycle consists of 15 minute holding at 523K under 300rpm revolution and 15 minute-natural cooling. Contact angle was measured and microstructure of the coating layer was observed by using a scanning electron microscope. Results: Four kinds of commercial repellent coating showed hydrophobic or super-hydrophobic property implying that all coatings are suitable for room temperature application. Contact angle of three kinds of commercial coatings decreased rapidly after thermal exposure, while only one specimen having hydrophobic surface showed extremely slow degradation. Conclusion: Observed decrease in contact angle of the coatings were attributed to formation of macro-sized pores and disappearance of micro-protrusion during thermal exposure. Optimum water-repellent coating needs to be selected under the consideration of initial contact angle as sell as service temperature.

• Particle and aerosol research
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• v.5 no.4
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• pp.159-170
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• 2009

A depth filter medium was newly designed in order to achieve high collection of dust and low pressure drop in this work. Multilayer depth filter media consist of an upstream layer of highly porous structure which allows particles to pass through and to follow by one or more downstream layers to hold the particles inside the media. For each filter media, flat sheet and pleated module were made of newly developed depth filter media and filter media of commercial products. Commercial depth filter cartridge for gas turbine air intake cleaning were used as reference for filtration area and pleat geometry of pleated modules. This work attempts to evaluate and compare the newly developed depth filter medium and two commercial filter media in terms of filtration parameters such as air permeability, initial pressure drop, particle retention and pressure drop variation with dust loading. According to the close examination the newly developed depth filter showed better performance compared to the commercial depth filter media.

• Proceedings of the IEEK Conference
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• 2002.07a
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• pp.560-563
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• 2002

This paper proposes a home control system architecture that have network configuration function. The proposed home control system architecture is implemented with partly hardware and software. For implementation of this system architecture, we developed ECONICS which is home automation controller. ECONICS consists of main board and communication modem. This communication modem supply the power line communication. The physical layer and the MAC layer software of EIA 709.1 standard protocol are implemented in communication modem. The upper layer software of EIA 709.1 standard protocol and home configuration software for home network installation, management, diagnostics, control and monitoring are implemented in main board of ECONICS. We verified the commercial feasibility of the proposed system through the home network configuration and operation. As a result, we have concluded that the proposed home control system architecture provides all the key function necessary to easily manage and control home network nodes.

• Journal of the Korea Furniture Society
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• v.21 no.5
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• pp.347-353
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• 2010

This research examined the technical feasibility of composite that had 2- and 3- layers of fiberglass reinforcement to enhance the load carrying capacity of particleboard. Specimens were prepared from commercial particleboard. Results indicated that bending properties, hardness and impact bending energy increased as the number of layers of fiberglass reinforcement increased. The wood screw withdrawal load only decreased at the 3-layer of fiberglass reinforcement. The technique developed by this study may increase an opportunity to use particleboard for structural purposes.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.10 no.4
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• pp.57-63
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• 2011

The aim of this study is to analyze turning process using commercial FEM simulation code. Various simulation models of orthogonal cutting process for 3 layers of metallic material have been simulated and analyzed. The workpiece material used for the orthogonal plane-strain metal cutting simulation consists of three layers, which are Allow Tool Steel, Aluminum and Stainless Steel. The finite element model is composed of a deformable workpiece and a rigid tool. The tool penetrates through the workpiece at a constant speed and constant feed rate. As an analytical result, detailed cutting temperature, strain, pressure, residual stress for both a tool and each layer of workpiece were obtained during the turning process. It has been closely observed that the chip flow curve deforms continuously.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.810-813
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• 2003

Application of inorganic silica-neodymia alloy films grown by sputtering technology to the dielectric layer of plasma display panel (PDP) is presented. The experimental results reveal that dielectric constant of the alloy films increases with neodymia concentration. Also, the alloy films act as band rejection color filter owing to sharp absorptions originating in the intratransition within the 4f shell of the $Nd^{3+}$ ion. In the optical band pass region, the transmittances of the alloy films show higher than those of commercial glass-like dielectrics. As a result, the luminance of PDP device with the alloy dielectric layer is higher than that of device with conventional dielectrics, indicating wider color gamut and higher color purity.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.160-163
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• 2002

Silica waveguide for an integrated diffractive optical head system was designed and fabricated. The waveguide was designed to optimize the optical efficiency of red and/or blue laser source, and a lab-made RF magnetron sputter was adopted to deposit silica cladding and core layers on SiO$_2$/Si substrates. The cladding and core layers were formed using commercial targets, and the former was done with ＃7740 and the latter with BK7 and BAK4, respectively The surface roughness of the waveguide layers was measured to be 30.3${\AA}$ for BK7 and 17.8${\AA}$ for BAK4, and the difference of refractive indices between core and cladding layers was 0.9% and 2.5%, respectively. The waveguide fabricated with the core layer of BK7 showed better optical properties when the final diffractive optical probe heads were measured with red laser(650nm) source.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.7
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• pp.991-996
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• 2010

Blue-green and green LEDs have been successfully fabricated grown by MBE, which has introduced the $ZnS_ySe_{1-x-y}:Te_x$ (x=0.04, y~0.11-0.14) ternary epilayer as an active layer. From the I-V characteristics, the built-in voltage (~2.1 V) is very small compared to other wide bandgap LEDs, such as commercial InGaN-based LEDs (>3.2 V). From the C-V profiling, the effective carrier concentration in the p-type ZnMgSSe cladding layer was evaluated as ${\sim}2.8{\times}10^{16}\;cm^{-3}$ for the present LEDs.