• 한국초전도학회:학술대회논문집
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• 2008.08a
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• pp.16-16
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• 2008

• The Transactions of the Korean Institute of Power Electronics
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• v.24 no.6
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• pp.411-418
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• 2019

Light-triggered thyristors (LTTs) are essential components in high-power applications, such as HVDC transmission and several pulsed-power applications. Generally, LTT fabrication includes a deep diffusion of aluminum as a p-type dopant to form a uniform p-base region, which needs careful concern for contamination and additional facilities in silicon semiconductor manufacturing factories. We fabricated 4-inch 5,000 V LTTs with boron implantation and diffusion process as a p-type dopant. The LTT contains a main cathode region, edge termination designed with a variation of lateral doping, breakover diode, integrated resistor, photosensitive area, and dV/dt protection region. The doping concentration of each region was adjusted with different doses of boron ion implantation. The fabricated LTTs showed good light triggering characteristics for a light pulse of 905 nm and a blocking voltage (V_DRM) of 6,500 V. They drove an average on-state current (I_TAVM) of 2,270 A, peak nonrepetitive surge current (I_TSM) of 61 kA, critical rate of rise of on-state current (di/dt) of 1,010 A/㎲, and limiting load integral (I²T) of 17 MA²s without damage to the device.

• Quality Improvement in Health Care
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• v.12 no.2
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• pp.113-123
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• 2006

Objective : This research is focused on understanding the current status of the Health Smart Card already in use in other advanced countries. This research will analyze the current status of the medical institutions Health Smart Card system adoption process and its effects, and provide a basis for future policy decisions for the effective adoption and diffusion of a Health Smart Card system, in the medical field, through the completed research and analysis. Method : This research surveys the domestic, and foreign, status of Health Smart Card usage. The research also presents up-to-date methodology for the evaluation of the effects of medical and health care technology. The research also conducts a survey of the domestic medical institutions that have implemented a Health Smart Card system, and then analyzes the results of the survey. Additionally, the research carried out a survey and analysis of medical institutions with no Health Smart Card system implemented, and considered the factors affecting the diffusion of Health Smart Card systems in considering an effective policy for the introduction and diffusion of such a system. Research Results : Through the study of the methodology of medical and health care information technology in advanced countries, the methodology for assessing Health Smart Card technology has been established, and focuses on 6 aspects. The study on the status of foreign implementation has shown a model for the Health Smart Card system. A survey was conducted on the current status of medical institutions with an implemented Health Smart Card system, and the survey results have been analyzed. Also, factors influencing the adoption of Health Smart Card systems have been analyzed through the survey on those medical institutions that have not implemented a Health Smart Card system. Conclusion : The government must provide institutional measures for sharing medical records by constructing an IT infrastructure at the national level to enable the adoption and diffusion of a Health Smart Card system. Such a network will make connections between medical institutions possible, thus making the diffusion of the Health Smart Card system nationwide. For the successful adoption and diffusion of a Health Smart Card system, a model system development, under a medical record sharing system, should be conducted. Additionally, a regional unit based model should be developed for the model project, as is done in advanced countries, along with the application of such results.

• Proceedings of the KIEE Conference
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• 1999.07d
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• pp.1704-1706
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• 1999

$YBa_2Cu_3O_x$ superconducting thick film was fabricated by surface diffusion process of $Y_2BaCUO_5$ and the mixed compound of $(3BaCuO_2+2CuO)$ expected to be liquid phase above the peritectic temperature of YBa2Cu30x. For the surface diffusion. 3BaCu02+2CuO mixed with binder material was patterned on $Y_2BaCuO_5$ substrate by the screen printing method. The characteristic of current limit on thick film fabricated was measured. The thick film limited the current from $2.8213mA_{rms}$ to $4.2034mA_{rms}$ with $500{\Omega}$ load resistance, and from $4.1831mA{rms}$ to $4.2150mA_{rms}$ with $10{\Omega}$ load resistance.

• Journal of the Korean Society of Combustion
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• v.3 no.1
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• pp.71-78
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• 1998

The flame stabilization and the combustion characteristics of diffusion flame formed in the wake of a cylindrical bluff body with fuel injection are studied. With the turbulence generator, the flame stability limits and ion currents were measured and analyzed. The results from this experimental study are summarized as follows. The region with highest average value of ion currents in the middle of flame is moved to the upstream side by the turbulent components of main stream. The flame mass with partially active reaction is moved fast for uniform flow and turbulence generator G3, but the flame mass with relatively slow reaction is moved slowly for turbulence generator G1. If the turbulence generator with strong turbulent component is installed, the turbulent time scale is increased with movement from main stream side to recirculation zone as well as the flame stability limits is deteriorated. Though the special dominant frequency is not appeared in the eddy which exists in flame, high frequency characteristics are appeared in uniform flow and turbulence generator G3, and low frequency characteristics are appeared in uniform flow, turbulence generator G3 and G1.

• 한국초전도학회:학술대회논문집
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• v.9
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• pp.242-246
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• 1999

For the fabrication of fault current limiting device using HTSC thick film, YBa$_2Cu_3O_x$ superconducting thick film was formed by surface diffusion process of the Y$_2BaCUO_5$ and the mixed compound of (3BaCuO$_2$+2CuO) expected to be liquid phase above the peritectic temperature of YBa$_2Cu_3O_x$. For the surface diffusion, the compounds of 3BaCuO$_2$+2CuO mixed with binder material was patterned on Y$_2BaCUO_5$ substrate by the screen printing method. After proper sintering, the characteristics of current limit on thick film fabricated was measured. The thick film was able to limit the current from 2.8213 mA$_{rms}$nu to 4.2034 mA$_{rms}$ with 500${\omega}$ load resistance, and from 4.1831 mA$_{rms}$ to 4.2150 mA$_{rms}$ with 10${\omega}$ load resistance.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2000.11a
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• pp.115-120
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• 2000

The analysis of flux distribution under stead-state in large power reactors with assymetry reactivity insertions requires the use of three-dimensional diffusion calculations. For the purpose, consistently formulated modern nodal methods based on higher order interface techniques have become popular tools for flux distributions in large commercial nuclear reactors. Among the earlier developments, the nodal Green's function method obtains its nodal interface equation from the transverse-integrated integral diffusion equation using a finite-medium Green's function. In this method, the outgoing current from a node surface is formulated as a response of the incoming currents and the spatially integrated neutron source within the same node. The well-known nodal expansion method is also based on an interface partial current formulation. Nodal methods high-level interface variables, i.e., interface net current and flux, may be more computationally efficient than the nodal Green's function method because they have one fewer unknown per interface. The Analytic Nodal Method(ANM), which can be classified as an interface net current technique and, was faster in solving some standard benchmark problems than the other two methods.(omitted)

• Korean Journal of Materials Research
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• v.32 no.2
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• pp.107-113
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• 2022

Fibrous supercapacitors (FSs), owing to their high power density, good safety characteristic, and high flexibility, have recently been in the spotlight as energy storage devices for wearable electronics. However, despite these advantages, FCs face many challenges related to their active material of carbon fiber (CF). CF has low surface area and poor wettability between electrode and electrolyte, which result in low capacitance and poor long-term stability at high current densities. To overcome these limits, fibrous supercapacitors made using surface-activated CF (FS-SACF) are here suggested; these materials have improved specific surface area and better wettability, obtained by introducing porous structure and oxygen-containing functional groups on the CF surface, respectively, through surface engineering. The FS-SACF shows an improved ion diffusion coefficient and better electrochemical performance, including high specific capacity of 223.6 mF cm^-2 at current density of 10 ㎂ cm^-2, high-rate performance of 171.2 mF cm^-2 at current density of 50.0 ㎂ cm^-2, and remarkable, ultrafast cycling stability (96.2 % after 1,000 cycles at current density of 250.0 ㎂ cm^-2). The excellent electrochemical performance is definitely due to the effects of surface functionalization on CF, leading to improved specific surface area and superior ion diffusion capability.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.3
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• pp.1028-1039
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• 1996

This study was focused on the examination of the flame structure and the combustion characteristics of diffusion flame which was formed the turbulent shear flow of a double coaxial air jet system. The shear flow was formed by the difference velocity of surrounding air jet(U$\_$s/) and center air jet (U$\_$c/). So experimental condition was divided S-type flame (.lambda. > 1) and C-type flame (.lambda. < 1) by velocity ratio .lambda. (=U$\_$s//U$\_$c/). For examination of the flame structure and the combustion characteristics in diffusion flame, coherent structure was observed in flame by schlieren photograph method. We measured fluctuating temperature and ion current simultaneously and accomplished the statistical analysis of its. According to schlieren photograph, the flame was stabilized in the rim of the direction of lower velocity air jet, coherent eddy was produced and developed by higher velocity air jet. The statistical data of fluctuating temperature and ion current was indicated that reaction was dominated by higher velocity air jet. The mixing state of burnt gas and non-burnt gas was distributed the wide area at Z = 100 mm of C-type flame.

• Corrosion Science and Technology
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• v.16 no.2
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• pp.64-68
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• 2017

The interactions between corrosion pits on stainless steel under loading conditions are studied by using a cellular automata model coupled with finite element method at a mesoscopic scale. The cellular automata model focuses on a metal/film/electrolyte system, including anodic dissolution, passivation, diffusion of hydrogen ions and salt film hydrolysis. The Chopard block algorithm is used to improve the diffusion simulation efficiency. The finite element method is used to calculate the stress concentration on the pit surface during pit growth, and the effect of local stress and strain on anodic current is obtained by using the Gutman model, which is used as the boundary conditions of the cellular automata model. The transient current characteristics of the interactions between corrosion pits under different simulation factors including the breakdown of the passive film at the pit mouth and the diffusion of hydrogen ions are analyzed. The analysis of the pit stability product shows that the simulation results are close to the experimental conclusions.