• 한국지구물리탐사학회:학술대회논문집
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• 2007.06a
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• pp.157-162
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• 2007

Geophysical survey has been conducted on the continental margin off the South Shetland Islands aboard R/V Onnuri of KORDI in 1992/1993. About 800-line km of 96-channel reflection data have been acquired. On the seismic section, BSR with strong reflectivity and negative polarity has been found at 700 ms below the sea bottom. BSR is considered as the base of gas hydrates and AVO analysis was performed to study physical properties along BSR. True amplitude recovery and surface consistence amplitude were applied to seismic data and angle gathers were obtained. AVO gradient and AVO intercept are calculated on every CDP gather. Section of AVO intercept show strong reflectivity and negative polarity on BSRs and stronger continuity of BSR than stacked section. Cross plot of intercept-gradient indicates that the lower layer below BSR is filled with free gas.

• Korean Journal of Materials Research
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• v.13 no.4
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• pp.271-278
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• 2003

Conventional backlight for liquid crystal display (LCD) uses mercury which leads to environmental pollution. In this study, characteristics of AC coplanar type mercury-free plasma flat lamp have been studied. Pollution-free Xe-He is adopted as a discharge gas system. Since the Xe gas has a lower efficiency in generating vacuum ultraviolet (VUV) than mercury, the improvement of luminance and luminous efficiency in the Xe gas system is very important. The electrode, dielectric, and phosphor layers constituting lamp are formed on the bottom glass by the screen printing method. The effects of pulse shape, on-time, and pulse frequency on the luminance and luminous efficiency have been examined. For Xe(5%)-He gas, the lamp exhibits higher efficiency with sharper pulse shape, higher peak voltage, and shorter pulse on-time (up to 2 $\mu\textrm{s}$). Higher efficiency and lower consumption of power were obtained at 30 kHz than at 60 kHz. The collision of ion to bottom electrodes is a dominant factor to raise the lamp temperature. Therefore the high voltage and low current discharge system is necessary for reduction of the lamp temperature as well as for enhancement of the luminous efficiency.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.2424-2426
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• 2005

In whole world consciousness of environment maintenance have increased very quickly for he end of the 20th century. To use and disuse toxic substances have been controled at the field of industry. Also the field of lighting source belong to environmental control. And in the future the control will be strong. In radiational mechanism of fluorescence lamp mercury is the worst environmental problem. In radiational mechanism of fluorescence lamp mercury is the worst environmental problem root. In the mercury free lighting source system the Xe gas lamp is one type. And the Ne:Xe and Ne:Ar mixing gas lamp improvements firing voltage of Xe gas lamp. Purpose and subject of this study are understand, efficiency, ideal of Ne:Xe and Ne:Ar plasma which mercury free lamp. Before ICP was designed, basic parameters of plasma, which are electron temperature and electron density, were measured and calculated by langmuir probe data. Property of electron temperature and electron density were confirmed by changing ratio of Ne:Xe and Ne:Ar.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.12a
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• pp.91-95
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• 2006

In whole world consciousness of environment maintenance have increased very quickly for the end of the 20th century. To use and disuse toxic substances have been controled at the field of industry. Also the field of lighting source belong to environmental control. And in the future the control will be strong. In radiational mechanism of fluorescence lamp mercury is the worst environmental problem. In radiational mechanism of fluorescence lamp mercury is the worst environmental problem root. In the mercury free lighting source system the Xe gas lamp is one type. And the Ne:Xe mixing gas lamp improvements firing voltage of Xe gas lamp. Purpose and subject of this study are understand, efficiency, ideal of Ne:Xe plasma which mercury free lamp. Before ICP was designed, basic parameters of plasma, which are electron temperature and electron density, were measured and calculated by langmuir probe data. Property of electron temperature and electron density were confirmed by changing ratio of Ne:Xe.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.2
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• pp.697-709
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• 1996

Supersonic axisymmetric jets issuing from various kinds of nozzles with a throat diameter of a few millimeters were experimentally investigated. The exit Mach number and Reynolds number based on the throat diameter of nozzle were in the range of 1.0 ~ 5.9 and 8.4$\times$ $10^4$ ~ 2.9$\times$$10^6$, respectively. The nozzle pressure ratio was varied from 5 to 85. Present paper aims to offer fundamental information of the supersonic free-jets, with an emphasis to give data with which the shape of the free-jets can be depicted under a specified condition. Experimental data are summarized to enable an estimation of the shape of the supersonic free-jets. The result shows that the shape of free-jets is dependent on only the nozzle pressure ratio.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.31 no.4
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• pp.244-248
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• 2018

We propose a method for improving the reliability of a solar cell by applying a fluorinated surface coating to protect the cell from the outdoor environment using an atmospheric pressure plasma (APP) treatment. An APP source is operated by radio frequency (RF) power, Ar gas, and $O_2gas$. APP treatment can remove organic contaminants from the surface and improve other surface properties such as the surface free energy. We determined the optimal APP parameters to maximize the surface free energy by using the dyne pen test. Then we used the scratch test in order to confirm the correlation between the APP parameters and the surface properties by measuring the surface free energy and adhesive characteristics of the coating. Consequently, an increase in the surface free energy of the cover glass caused an improvement in the adhesion between the coating layer and the cover glass. After treatment, adhesion between the coating and cover glass was improved by 35%.

• Nuclear Engineering and Technology
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• v.54 no.2
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• pp.565-578
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• 2022

Among Generation IV reactors, the sodium-cooled fast reactor (SFR) is attracting attention as a system having great potential for commercial use. Gas entrainment is a thermal-hydraulic issue related to the safety problem of the reactor core in the SFR. Typically, a dipped plate or baffles are installed under the free surface to suppress gas entrainment. However, these approaches can cause gas entrainment in other locations and require many trial-and-error and verifications. In this study, a new strategy using magnetohydrodynamics to suppress gas entrainment in the SFR is proposed. In a counter-flow model, a judgment criterion of gas entrainment occurrence was developed for both water and liquid metal. Moreover, the gas entrainment can be completely suppressed by applying a magnetic field.

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.371-374
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• 2006

The objective of this study is to determine the influence of free-stream turbulent intensity on the three-dimensional turbulent flow in a linear turbine cascade. The range of free-stream turbulence intensity considered is 0.7~10%. This study was performed numerically. The results show that the mass averaged loss coefficient increased according to the increase of free-stream turbulence intensity due to increased value of the mass averaged total pressure loss coefficient which was higher than the decreased value of the mass averaged secondary flow loss coefficient. The loss coefficient distribution was changed suddenly at a free-stream turbulence intensity of 10% while the loss coefficient distribution was rarely changed at a lower free-stream turbulence intensity of 5%.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1577-1579
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• 2007

Xe content is one of important factors related to characteristics of the mercury-free flat fluorescent lamp. The electro-optical properties of lamp were investigated for wide range of Xe content in Xe-Ne mixing gas. The maximum luminance of $9,289\;cd/m^2$ and efficacy of 3 lm/W was obtained with Xe 90 %.

• Resources Recycling
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• v.12 no.5
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• pp.42-49
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• 2003

Characteristics of reduction and carbidization for hematite ore with a wide size range have been investigated at high temperature(590∼64$0^{\circ}C$) under $H_2$ and $H_2$-CO gas mixtures. The apparent activation energy for reduction of hematite ore with H2 gas was found to be 20 kJ/mol. The weight loss by reduction was about 28% md the weight gain by carbidization was about 5%. The measured values of weight change were compared with those calculated from equation (3) & (5) and fairly good agreement was obtained. The rate of carbidization was increased with an decrease in temperature, particle diameter and gas ratio($H_2$/ CO). The free carbon was increased with decrease in gas ratio($H_2$/ CO). The rate of carbidization was increased with mixing of $H_2$ gas but this effect was not proportional to fraction of $H_2$ gas. It was also found that the rate of carbidization was the maximum in the $H_2$ gas fraction of 0.5. It is considered that $H_2$ plays a part as a catalyst for formation of iron carbide($Fe_3$C).