• Journal of Korean Neurosurgical Society
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• v.63 no.4
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• pp.519-531
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• 2020

Objective : The purpose of this study is identify the operation status of the neurosurgical care units (NCUs) in neurosurgical residency training hospitals nationwide and determine needed changes by comparing findings with those obtained from the Korean Neurosurgical Society (KNS) and Korean Society of Neurointensive Care Medicine (KNIC) survey of 2010. Method : This survey was conducted over 1 year in 86 neurosurgical residency training hospitals and two neurosurgery specialist hospitals and focused on the following areas : 1) the current status of the infrastructure and operating systems of NCUs in Korea, 2) barriers to installing neurointensivist team systems, 3) future roles of the KNS and KNIC, and 4) a handbook for physicians and practitioners in NCUs. We compared and analyzed the results of this survey with those from a KNIC survey of 2010. Results : Seventy seven hospitals (87.5%) participated in the survey. Nineteen hospitals (24.7%) employed a neurointensivist or faculty member; Thirty seven hospitals (48.1%) reported high demand for neurointensivists, and 62 hospitals (80.5%) stated that the mandatory deployment of a neurointensivist improved the quality of patient care. Forty four hospitals (57.1%) believed that hiring neurointensivist would increase hospital costs, and in response to a question on potential earnings declines. In terms of potential solutions to these problems, 70 respondents (90.9%) maintained that additional fees were necessary for neurointensivists' work, and 64 (83.1%) answered that direct support was needed of the personnel expenses for neurointensivists. Conclusion : We hope the results of this survey will guide successful implementation of neurointensivist systems across Korea.

• Journal of Astronomy and Space Sciences
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• v.35 no.3
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• pp.201-210
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• 2018

The characterization of detectors installed in space- and ground-based instruments is important to evaluate the system performance. We report the development of a detector performance test system for astronomical applications using the Andor iKon M CCD camera. The performance test system consists of a light source, monochromator, integrating sphere, and power meters. We adopted the Czerny-Tuner monochromator with three ruled gratings and one mirror, which covers a spectral range of 200-9,000 nm with a spectral resolution of ~1 nm in the visible region. Various detector characteristics, such as the quantum efficiency, sensitivity, and noise, can be measured in wide wavelength ranges from the visible to mid-infrared regions. We evaluated the Korea Astronomy and Space Science Institute (KASI) detector performance test system by using the performance verification of the Andor iKon-M CCD camera. The test procedure includes measurements of the conversion gain ($2.86e^-/ADU$), full well capacity ($130K\;e^-$), nonlinearity, and pixel defects. We also estimated the read noise, dark current, and quantum efficiency as a function of the temperature. The lowest measured read noise is $12e^-$. The dark current at 223 K was determined to be $7e^-/s/pix$ and its doubling temperature is $5.3^{\circ}C{\pm}0.2^{\circ}C$ at an activation energy of 0.6 eV. The maximum quantum efficiency at 223 K was estimated to be $93%{\pm}2%$. We proved that the quantum efficiency is sensitive to the operating temperature. It varies up to 5 % in the visible region, while the variation increases to 30 % in the near-infrared region. Based on the comparison of our results with the test report by the vendor, we conclude that our performance test results are consistent with those from the vendor considering the test environment. We also confirmed that the KASI detector performance test system is reliable and our measurement method and analysis are accurate.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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• pp.102-102
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• 2018

Electronic industry had required the finer size and the higher performance of the device. Therefore, 3-D die stacking technology such as TSV (through silicon via) and micro-bump had been used. Moreover, by the development of the 3-D die stacking technology, 3-D structure such as chip to chip (c2c) and chip to wafer (c2w) had become practicable. These technologies led to the appearance of HBM (high bandwidth memory). HBM was type of the memory, which is composed of several stacked layers of the memory chips. Each memory chips were connected by TSV and micro-bump. Thus, HBM had lower RC delay and higher performance of data processing than the conventional memory. Moreover, due to the development of the IT industry such as, AI (artificial intelligence), IOT (internet of things), and VR (virtual reality), the lower pitch size and the higher density were required to micro-electronics. Particularly, to obtain the fine pitch, some of the method such as copper pillar, nickel diffusion barrier, and tin-silver or tin-silver-copper based bump had been utillized. TCB (thermal compression bonding) and reflow process (thermal aging) were conventional method to bond between tin-silver or tin-silver-copper caps in the temperature range of 200 to 300 degrees. However, because of tin overflow which caused by higher operating temperature than melting point of Tin ($232^{\circ}C$), there would be the danger of bump bridge failure in fine-pitch bonding. Furthermore, regulating the phase of IMC (intermetallic compound) which was located between nickel diffusion barrier and bump, had a lot of problems. For example, an excess of kirkendall void which provides site of brittle fracture occurs at IMC layer after reflow process. The essential solution to reduce the difficulty of bump bonding process is copper to copper direct bonding below $300^{\circ}C$. In this study, in order to improve the problem of bump bonding process, copper to copper direct bonding was performed below $300^{\circ}C$. The driving force of bonding was the self-annealing properties of electrodeposited Cu with high defect density. The self-annealing property originated in high defect density and non-equilibrium grain boundaries at the triple junction. The electrodeposited Cu at high current density and low bath temperature was fabricated by electroplating on copper deposited silicon wafer. The copper-copper bonding experiments was conducted using thermal pressing machine. The condition of investigation such as thermal parameter and pressure parameter were varied to acquire proper bonded specimens. The bonded interface was characterized by SEM (scanning electron microscope) and OM (optical microscope). The density of grain boundary and defects were examined by TEM (transmission electron microscopy).

• Applied Chemistry for Engineering
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• v.16 no.4
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• pp.485-490
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• 2005

Effects of gas injectino on the copper recovery form industrial waste water in a fluidized-bed electrolytic reactor were investigated. Effects of gas injection on the individual phase holdup and efficiency of copper recovery for given operating variables such as liquid and gas velocity (0.1~0.4 cm/s), current density ($2.0{\sim}3.5A/dm^2$) and amount of fluidized solid particles (1.0~4.0 wt%) were examined. The solid particle, whose diameter and swelling density were 0.5 mm and $1100kg/m^3$, respectively, was made of polystylene and divinyl benzene. It was found that the holdup of gas and solid phases increased, but that of the liquid phase decreased with increasing velocity of gas injected into the reactor. With increasing gas and/or liquid velocity and increasing amount of fluidized particles is not needed, the rate of copper recovery increased to a maximum value of and subsequently decreased. The recovery rate of copper increased almost linearly with increasing current density in accordance with Faraday's law.

• Journal of Energy Engineering
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• v.29 no.2
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• pp.1-9
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• 2020

In recent days, fuel cell has received attention from the world as an alternative power source to hydrocarbon used in automobile engines. With the industrial advances of fuel cell, There have been a lot of researches actively conducted to find a way of generating hydrogen. Among many hydrogen production methods, Solid Oxide Electrolysis Cell(SOEC) is not only a basic way but also environment-friendly method to produce hydrogen gas. Solid Oxide Electrolysis Cell has lower electrical energy demands and high thermal efficiency since it is possible to operate under high temperature and high pressure conditions. For these reasons, experimental researches as well as studies on numerical modeling for Solid Oxide Electrolysis Cell have been under way. However, studies on numerical modeling are relatively less enough than experimental accomplishments and have limited performance prediction, which mostly is considered as a result from inadequate effects of electrochemical properties by temperature and pressure. In this study, various experimental studies of commercial Membrane Electrode Assembly (MEA) composed of Ni-YSZ (40wt%, Ni-60 wt% YSZ)/8-YSZ (TOSOH, TZ8Y)/LSM (La_0.9Sr_0.1MnO₃) was utilized for improving effectiveness of SOEC model. After numerically analyzing effects of electrochemical properties according to operating temperature, causing the largest deviation between experiments and simulation are that Charge Transfer Coefficient (CTC), exchange current density, diffusion coefficient, electrical conductivity in SOEC. Analyzing temperature effect on parameter used in overpotential model is conducted for modeling of SOEC. cross-validation method is adopted for application of various MEA and evaluating feasibility of model. As a result, the study confirm that the numerical model of SOEC based on structured process of effectiveness evaluation makes performance prediction better.

• Proceedings of the Korea Society for Industrial Systems Conference
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• 2002.06a
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• pp.433-445
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• 2002

This study is to consider the current status of e-payment of local tax, one of the e-business models between Government and Customers(G2C) which is designed for the implementation of e-Government, and to present the activated policy for e-payment of local tax. For the survey, the complete enumeration is conducted through the questionnaire survey with those people who have used the e-payment tax system in C county and interview with those officials who are in charge of tax affairs in 232 local autonomies in Korea. As the system introduction status is viewed, the e-payment of local tax system is operated in 196 cities and counties in nation-wide but it has shown big differency in the extent of utilization according to regions. And the way of system operation is varied and the age bracket of those users is mainly comprised of 30's. In sum, a severe gap among taxpayer's age group, regional difference, and the lag of information in the system infra is appeared. But users consider this system to be settled as a new tax-payment system, and the good prospect is anticipated. As an activating policy for the e-payment of local-tax, some measures-providing incentives to those users of e-payment of tax system, improving the operating system, and enhancing the information education for taxpayer's-are needed to be taken. Hereafter, in-depth study on the e-payment tax system which is planned for the realization of e-Government is expected through a more systematic and scientific approach to this field.

• International Commerce and Information Review
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• v.13 no.1
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• pp.29-52
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• 2011

A predictable and manageable output is desirable for most businesses. However, it is very difficult to control the quality and quantity of products in the food and agriculture business. Predictable outputs help managers plan their marketing, sales, and inbound and outbound logistics, but these are not easy to achieve in the food and agriculture business. Various industries have adopted different levels of automation and utilization of information systems for quality/quantity control; however e-Commerce of the food and agriculture industry is far behind those of other industries. Today, the food and agriculture industry is supposed to be more integrated than ever in order to reduce risks and improve processing costs, from farm to table. Since its operations including production, processing, storage, distribution, and management are dispersed all over the world, the food and agricultural industries now depend more on IT than other industries. This study attempts to develop a framework to analyze the current situation of agricultural product e-Commerce in Korea, and finds out the actual situation of the farmers operating on-line shopping systems through the developed framework and suggests some improvements.

• Korean Chemical Engineering Research
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• v.45 no.3
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• pp.242-248
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• 2007

For an optimal design of automotive electric system, it is important to have a reliable modeling tool to predict the charge-discharge behaviors of the automotive battery. In this work, a two-dimensional modeling was carried out to predict the charge-discharge behaviors of a 12-V automotive lead-acid battery. The model accounted for electrochemical kinetics and ionic mass transfer in a battery cell. In order to validate the modeling, modeling results were compared with the experimental data of the charge-discharge behaviors of a lead-acid battery. The discharge behaviors were measured with three different discharge rates of C/5, C/10, and C/20 at operating temperature of $25^{\circ}C$. The batteries were charged with constant current of 30A until the charging voltage reached to a predetermined value of 14.24 V and then the charging voltage was kept constant. The discharge and charge curves from the measurements and modeling were in good agreement. Based on the modeling, the distributions of the electrical potentials of the solid and solution phases, the porosity of the electrodes, and the current density within the electrodes as well as the acid concentration can be predicted as a function of charge and discharge time.

• The Korean Society of Law and Medicine
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• v.16 no.2
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• pp.227-261
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• 2015

Cooperative associations are established in order to enhance the rights and the interests of their members and serve the local communities, and actually do much for the local society. And among these, consumer cooperatives are spontaneously founded, particularly in the spirit of mutual help, in order to promote the common welfare of the members. Meanwhile, because the current medical law qualifys noncommercial corporation to open medical institution, consumer cooperative and noncommercial- corporation cooperative which are established under the Cooperative Act have the right to do. However, though cooperative association should be founded for common interests of the members who are weaker parties of society, it became rapidly to be abused as means of circumvention of law. Especially as National Health Insurance Corporation stepped up the investigation and the collection of unfair profits against the hospital owned by non-medical personnel who are unable to establish a medical institution, setting up medical institutions as a roundabout way to avoid the restricts dramatically increased in number. In this study, we are going to introduce the current dualised normative system regulating the establishment of a medical cooperative association, and find a way to improve the system and make up for the week points. And we will look though the present situation about medical cooperative association's opening, operating, and closing, and review the normative and systematic improving plans.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.8
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• pp.751-758
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• 2017

The behavior of fatigue crack growth of nickel-based powder metallurgy superalloy that could be used in aircraft turbine disc is investigated at room temperature, and $650^{\circ}C$ considering real operating conditions. The direct current potential drop(DCPD) method was used to measure the crack length of material in real time according to ASTM E647. Tests were performed with various stress ratios (0.1 and 0.5). Experimental results show that stress ratio, and temperature all affect the behavior of fatigue crack growth. As the stress ratio and temperature increase, the fatigue crack growth rate of nickel-based powder metallurgy superalloy also increases. Results were compared and reviewed with fatigue crack growth rates of other nickel-based superalloy materials (Inconel-100) that were studied in previous papers. Fractography analysis of the fractured specimens was performed using as SEM.