• Resources Recycling
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• v.21 no.5
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• pp.65-71
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• 2012

The equilibrium distribution of bismuth and lead between molten PbO-$SiO_2$ slag and bismuth phase was studied in the temperature range of $775^{\circ}C$ to $850^{\circ}C$ in a MgO crucible. The oxygen partial pressure of atmosphere was controlled by $P_{CO2}/P_{CO}$ ratio. The value of $(%PbO)_{slag}/[%Pb]_{metal}$ increased with increasing $SiO_2$ content of slag, and the value of $(%Bi_2O_3)_{slag}/[%Bi]_{metal}$ decreased with increasing $SiO_2$ content of slag. The concentration of Pb in metal increased with increasing temperature. These experimental results agreed well with the thermodynamic prediction.

• Journal of the Korean Vacuum Society
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• v.21 no.3
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• pp.121-129
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• 2012

RF biased inductively coupled plasma (ICP) is widely used in semiconductor and display etch processes which are based on vacuum science. Up to now, researches on how rf-bias power affects have been focused on the controls of dc self-bias voltages. But, effect of RF bias on plasma parameters which give a crucial role in the processing result and device performance has been little studied. In this work, we studied the correlation between the RF bias and plasma parameters and the recent published results were included in this paper. Plasma density was changed with the RF bias power and this variation can be explained by simple global model. As the RF bias was applied to the ICP, increase in the electron temperature from the electron energy distribution was measured indicating electron heating. Plasma density uniformity was enhanced with the RF bias power. This study can be helpful for the control of the optimum discharge condition, as well as the basic understanding for correlation between the RF bias and plasma parameters.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.10
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• pp.71-79
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• 2006

Swirl injector with multi-stage tangential entry was analyzed to suppress high-frequency combustion instability in Liquid Rocket Engines. In order to analyze the effect of swirl injector as an acoustic absorber, swirl injector was regarded as a quarter-wave resonator and it's damping capacity is verified in atmospheric temperature. It has a finite mode of vibration and natural frequencies which can be tuned to the natural frequencies of a model combustion chamber. The interior air core shape of injector is more stable in the case of using the swirl injector with multi-stage entry than with single-stage entry. Also, when the swirl injector with multi-stage entry is used, tuned-injector length for unstable mode is well agreed with the calculated length. From the experimental data, it is proved that if the interior air core shape of swirl injector is stable, the fine tuned swirl injector can decrease the unstable mode of model chamber effectively and increase the damping rate.

• Journal of Bio-Environment Control
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• v.9 no.4
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• pp.223-229
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• 2000

This study was conducted to analyze the opto-electric characteristics of light-emitting diodes(LED) designed for growth and morphogenesis control of transplant and to quantify the photon flux emittig from LED using a quantum sensor spectroradiometer. Difference in photon flux for blue and red LED between measured by a quantum sensor and measured by a spectroradiometer and numerically integrated was not observed. This result implies a spectroradiometer can be applied to quantify the photon flux emitting from far-red LED, which can not be measured using a quantum sensor. Since photon flux increases in proportion to wavelength, photon flux of LED modules arranged for red and far-red increased in proportion to wavelength, photon flux of LED modules arranged for red and rar-red increased gradually as the number of LED stick emitting far-red in LEd modules increased. Illumination of LED modules arranged for red and far-red decreased as the number of LED stick emitting far-red in LED modules increased. There was no difference in irradiance between LED modules arranged for red and far-red.

• The Journal of the Korea Contents Association
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• v.13 no.8
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• pp.466-473
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• 2013

Gene expression is regulated by a wide range of mechanisms at the DNA sequence level. In addition, gene expression is also regulated by epigenetic mechanisms through DNA methylation, histone modification, and ncRNA. To understand the regulation of gene expression at the epigenetic level, we constructed aging related gene database and analyzed epigenetic properties that are focused on DNA methylation. The DNA methylation of promoter or upstream region of the genes induces to repress the gene expression. We compared and analyzed distribution between whole human genes and aging related genes in the epigenetic properties such as CGI distribution, methylation motif pattern, and TFBS (transcription factor binding site) distribution. In contrast to methylation motif pattern, CGI and TFBS distributions are positively correlated with epigenetic regulation of aging related gene expression. In this study, the epigenetic data about DNA methylation of the aging genes will provide us to understand phenomena of the aging and epigenetic mechanism for regulation of aging related genes.

• Korean Journal of Cognitive Science
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• v.12 no.1_2
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• pp.55-63
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• 2001

Speaking generally, agent-based technology is a kind of technology to handle the flood of information resulted from the popularization of the internet. Agent system is a multi-distributed system which consists of both homogeneous and heterogeneous agents. Generally there is a coordination agent in between which is in charge of control and m message flow among the application agents. The purpose of this thesis is to propose a coordination method among agents, some of which provide informations and some of which request them. In multi-agent system, the Information Providing Agent(IPA) registers its capabilities to Coordination Agent(CA) and the Information Requesting Agent(lRA) requests CA what it needs. To coordinate them with satisfactory results the coordination agent ought to have an ability to return a relatively proper data to the requester which is supposed to be similar even though it is not so exact as was intended. For this, this thesis proposes a scheme for an coordination agent to find an IPA which provides an information which correlates most closely with that of IRA.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.6
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• pp.83-88
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• 2010

In this paper, to propose a valid method solving a problem relevant to grounding from actual field data, the experimental results relevant to touch and step voltages and surface potential profiles measured around the real-sized and small-sized grounding electrode models were described. The ground surface potential profiles and dangerous voltages around the concrete pedestals employed in street facilities such as street lamps, traffic signal lamp and controllers as a case study were measured and discussed. The hemispherical cell with a diameter of 1,160[mm] was employed to simulate uniform soil. As a result, the results measured with the small-sized model were in reasonably agreement with the data obtained from the real-sized installation. It was found that the small-sized model test could be employed as a useful means evaluating the dangerous voltages around grounding electrodes installed at the inaccessible areas such as mountains, underground, underwater, and so on.

• Journal of Korea Multimedia Society
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• v.4 no.5
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• pp.455-464
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• 2001

For future multimedia services, one of the most crucial issues is building an access network that can accommodate multimedia services in subscriber network. The VB5.2 interface of B-ISDN located between an access network and a service node allows dynamic allocation and release of ATM resources. The SG 13 of ITU-T is standardizing the B-BCC protocol, which is sequentially interworked with signaling protocols in the service node. To minimize a connection setup delay of the sequential interworking mode, we proposed the parallel interworking model in which the SN executes simultaneously the connection control protocol of VB5.2 interface and signaling protocol. We simulate two interworking models in terms of a connection setup delay and a completion ratio. The results of simulation show that our proposed parallel interworking model for the VB5.2 interface reduces the setup delay and has the similar completion ratio compared to the sequential interworking model. however, the connection setup delay of parallel interworking model becomes about seven tenths of that of the sequential interworking model and the improvement become larger as the arrival rate increased.

• Journal of the Society of Naval Architects of Korea
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• v.39 no.1
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• pp.49-60
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• 2002

Welding is essential in ship production since welding is very popular method for joining two or more metals. However, welding causes residual stress and distortion and these give a bad influence to the structure strength and assembly of ship blocks. Therefore, prediction and treatment of residual stress and distortion is a key to accuracy control in shipyard. In this paper, a computational procedure, based on thermal-elastic-plastic 3-dimensional FEA, has been suggested to simulate butt and fillet welding process. In the simulation process, temperature distribution at each time step is obtained by heat transfer analysis and then thermal deformation analysis is done with obtained temperature distributions to find the residual stress and distortion. In heat transfer analysis, enthalpy method is used to realize phase change at melting temperature. Also element birth and death method is used to simulate adding of weld metal in both heat transfer analysis and thermal elastic plastic analysis. The proposed procedure is verified by related researches and the results show good agreement with those of related researches.

• Korean Journal of Materials Research
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• v.11 no.8
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• pp.636-640
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• 2001

In order to improve the optical Performance of green emitting phosphor for plasma display panel (PDP) application, the wet chemical method for preparing $Zn_{2-x}$ $SiO_4$:xMn (xi=0.02. 0.08) phosphor was designed. The spherical phosphor particles were obtained and the size can be between 0.5$\mu\textrm{m}$ and 2$\mu\textrm{m}$. The formation of phosphor, which had the willemite structure, was completed at relatively low temperature of 108$0^{\circ}C$. Also, photoluminescence Properties of the phosphors prepared were investigated under vacuum ultraviolet excitation. In particular, the emission intensity of Zn$_2$SiO$_4$:0.08Mn phosphor having the 1$\mu\textrm{m}$ of particle size was higher than that of commercial phosphor by 40%. The decay time of zinc silicate powder prepared as containing 8 mole% of manganese has been measured as 7.8ms.