• Journal of the Korean Solar Energy Society
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• v.24 no.2
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• pp.39-50
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• 2004

One of the challenge for successful daylighting design might be to capture sunlighting that varies in both intensity and position and to deliver the luminous flux into the inner space as deep as possible. Conventional glazing apertures allow daylight in the outer 3.5m of a perimeter spaces. More advanced daylighting technologies can extend this daylighting depth by reflecting sunlight further from the windows within a deep floor area. For this purpose, this study developed light shelves based on performance evaluation with a mock-up model that constructed recently and measured under real sky condition. All these daylighting devices have a customized geometry developed from the solar path at a given latitude and utilize unique reflecting finishing to maximize the amount of redirection and diffusion of the daylight. This paper tells that the best daylighting penetration typically can be expected from using light-colored sloped external shelves.

• Journal of the Society of Naval Architects of Korea
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• v.50 no.6
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• pp.450-457
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• 2013

For the design guide of a vessel operating in cold region, numerical analysis was carried out to evaluate the weather-tight door which installed the heating cables by using ANSYS 13.0 Transient Thermal. The numerical analysis was performed by considering Advection-Diffusion equation. This study based on the experimental results of 'A study on Anti-Icing Technique for Weather-Tight Door of Ice-Strengthened Vessels'(Jeong, et al., 2011a) in KIOST. For validation of the numerical analysis results, the cold chamber experimental data measured by the heat sensors in certain location of the weather-tight door was used. The external environmental temperature which varies from $5^{\circ}C$ to $-55^{\circ}C$ was considered in numerical analysis. Also three different heating cables which have the heat capacity of 33W/m, 45W/m and 66W/m were adapted for the design parameters to be the most efficient and guidelines for anti-icing design of the weather tight door.

• Journal of the Korean Vacuum Society
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• v.9 no.2
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• pp.172-178
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• 2000

We developed the model equations to investigate the particle movement and growth theoretically in a-Si plasma CVD reactor, where those particles act as the source of contamination. We included the effects of fluid convection, particle diffusion and external forces (ion drag force, electrostatic force and gravitational force) onto the particles to analyze the movements of particles in plasma reactor. Taking into account the particle charge distribution, the particle growth by coagulation between the charged particles was investigated. Most of those particles are located in the region near the sheath boundaries by the balance between the ion drag and electrostatic forces. The particle concentrations in the sheath region and in the bulk plasma region are almost zero. The sizes of the predator particles increase with time by the coagulation with protoparticles and, as a result, the surface area and the average charge of predator particles also increase with time.

• Journal of the Microelectronics and Packaging Society
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• v.8 no.2
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• pp.1-7
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• 2001

In order to form a uniform oxidation layer of spinel phase on Kovar which helps the strong bonding in Kovar-to-glass sealing, the humidified $N_2/H_2$ was used as an oxidation atmosphere. The oxidation of Kovar was controlled by diffusion mechanism and the activation energy was 31.61 kacl/mol at 500~$800^{\circ}C$. After oxidation at $600^{\circ}C$, the external oxidation layer was below 0.5 $\mu \textrm{m}$ thick. According to TEM analysis, oxidized Kovar was spinel its lattice parameter of 7.9 $\AA$. Oxidation of under $600^{\circ}C$ and in a humidified $N_2/H_2$ atmosphere, Kovar was found to be appropriate for the Kovar-to-glass sealing.

• Journal of Environmental Health Sciences
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• v.38 no.1
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• pp.1-7
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• 2012

Carbon nanotubes (CNTs) stand at the frontier of nanotechnology and are destined to stimulate the next industrial revolution. Rapid increase in their production and use in the technology industry have led to concerns over the effects of CNT on human health and the environment. The prominent use of CNTs in biomedical applications also increases the possibility of human exposure, while properties such as their high aspect ratio (fiber-like shape) and large surface area raise safety concerns for human health if exposure does occur. It is crucial to develop viable alternatives to in vivo tests in order to evaluate the toxicity of engineered CNTs and develop validated experimental models capable of identifying CNTs' toxic effects and predicting their level of toxicity in the human respiratory system. Human lung epithelial cells serve as a barrier at the interface between the surrounding air and lung tissues in response to exogenous particles such as air-pollutants, including CNTs. Monolayer culture of the key individual cell types has provided abundant fundamental information on the response of these cells to external perturbations. However, such systems are limited by the absence of cell-cell interactions and their dynamic nature, which are both present in vivo. In this review, we suggested two viable alternatives to in vivo tests to evaluate the health risk of human exposure to CNTs.

• Journal of Environmental Science International
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• v.22 no.9
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• pp.1161-1170
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• 2013

The efficiency of coal-based activated carbon in removing methylene blue (MB) and phenol from aqueous solution was investigated in batch experiments. The batch adsorption kinetics were described by applying pseudo-first-order, pseudo-second-order, and first order reversible reaction. The results showed that the adsorption of MB and phenol occurs complexed process including external mass transfer and intraparticle diffusion. The maximum adsorption capacity obtained from Langmuir isotherm was 461.0 mg/g for MB and 194.6 mg/g for phenol, respectively. The values of activation parameters such as free energy (${\Delta}G^0$), enthalpy (${\Delta}H^0$), and entropy (${\Delta}S^0$) were also determined as -19.0~-14.9 kJ/mol, 25.4 kJ/mol, and 135.2 J/mol K for MB and 51.8~54.1 kJ/mol, -29.0 kJ/mol, and -76.4 kJ/mol K for phenol, respectively. The MB adsorption was found to be endothermic and spontaneous process. However, the CV adsorption was found to be exothermic and non-spontaneous process.

• Journal of Information Technology Applications and Management
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• v.22 no.1
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• pp.153-163
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• 2015

The purpose of this study is to investigate the relationship among factors that expand the win-win growth between domestic finished goods-making manufacturers and subcontractors. One-hundred twenty six firms participated for this study and were used for the data analysis. As a result of analysis, first, it was found that the win-win growth between first-tier suppliers and second-tier suppliers has positive effects on the win-win growth made by second-tier suppliers helping the third-tier suppliers. Second, it was found that the win-win growth policies supported by the government for the positive relationship between first-tier suppliers and second-tier suppliers for the finished goods-making manufacturers have positive effects on the win-win growth between second-tier suppliers and third-tier suppliers. Third, the results also showed that the win-win growth between second-tier suppliers and third-tier suppliers has a positive influence both on the financial and on the non-financial performances of the second-tier suppliers. Based on the results of this study, it is recommended to (1) construct infrastructure by sector through partnership between finished goods-making manufacturers and subcontractors, (2) draw in active support through the governmental win-win growth policies, (3) induce increasing productivities through information sharing, manpower support, technical support and educational support, and (4) strengthen and cultivate the culture of the small- and medium-sized companies.

• Journal of Electrochemical Science and Technology
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• v.5 no.2
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• pp.37-44
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• 2014

The $Li-O_2$ battery has been attracting much attention recently, due to its very high theoretical capacity compared with Li-ion chemistries. Nevertheless, several studies within the last few years revealed that Li-ion derived electrolytes based on alkyl carbonate solvents, which have been commonly used in the last 27 years, are irreversibly consumed at the $O_2$ electrode. Accordingly, more stable electrolytes are required capable to operate with both the Li metal anode and the $O_2$ cathode. Thus, due to their favorable properties such as non volatility, chemical inertia, and favorable behavior toward the Li metal electrode, ionic liquid-based electrolytes have gathered increasing attention from the scientific community for its application in $Li-O_2$ batteries. However, the scale-up of Li-$O_2$ technology to real application requires solving the mass transport limitation, especially for supplying oxygen to the cathode. Hence, the 'LABOHR' project proposes the introduction of a flooded cathode configuration and the circulation of the electrolyte, which is then used as an oxygen carrier from an external $O_2$ harvesting device to the cathode for freeing the system from diffusion limitation.

• Journal of Advanced Marine Engineering and Technology
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• v.24 no.3
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• pp.43-51
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• 2000

The effect of time, temperature and gas composition on the case hardened thickness, hardness and nitride formation in the surface of ductile cast iron(GCD400) have been studied by micro-pulse plasma technique. Typically, external compound layer and internal diffusion layer which is much thicker than compound layer was observed in the nitride hardening of ductile cast iron. The relative amount kind of phases formed in the nitrided hardening changed with the change of nitriding conditions. Generally, only nitride phases such as $\gamma^'$($Fe_4N$), or $\varepsilon$($Fe_{2-3}N$) phases were detected in compound layer by XRD analysis. The thickness of compound layer increased with the increase of nitrogen content in the gas composition. The optimum nitriding temperature was obtained at $520^{\circ}C$. The nitrided hardening thickness parabolically with nitriding time(t) and thus, the case hardened layer(d) fits well with the typical parabolic equation ; d=kt. The material constant k for GCD400 nitrided at $520^{\circ}C$ was $0.04919\times10^3{\mu}m.hr^{-1/2}$.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.2 no.3
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• pp.243-255
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• 1990

The objective of this study is to present an efficient measurement method of the effective thermal diffusivity for the fibrous insulation material. The non-linear parameter estimation (NPE) method is adapted for this analysis because of its accuracy and its results are compared with those by other direct methods such as CTP, CHP and STD method. A experimental system is constructed with bell-jar vaccum chamber, diffusion pump, tube type furnace, control unit and data acquisition system included with A/D converter and IBM XT/AT personal computer. The typical results obtained from this study are as follows; 1) NPE method can be recommended as an useful and accurate method to measure the effective thermal diffusivity of insuation material because it is shown that the measurement error compared with those by other direct methods is reduced for standard material, NBS-1450b. 2) NPE method can minimize the effects of ill-measured temperature due to external disturbance, because the final value is found by point to point estimating. 3) NPE method dose not depend on the kinds of heat flux, since the surfac temperature are used to estimate the thermal diffusivity. 4) With NPE method, compared with the steady state method, a measuring time and a sample size could be reduced.