• Convergence Security Journal
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• v.11 no.3
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• pp.55-66
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• 2011

This research focus on the value of smart phones for university students in Korea, considering on the correlations between the main causes influencing intrinsic value(price attributes, function attributes), network value(learning effects attributes, externalities attributes) user satisfaction, and intentions of repurchase of the smart phones market in Korea. Through the statistical analyses on the 8 hypotheses from a research model, we found that intrinsic value and network value gave an attentive influence on user satisfaction and repurchase intention. Call charge and Liquid crystal display and Design of smart phone have an influenced user satisfaction and repurchase intention.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.7
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• pp.575-582
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• 2000

The Electrical conduction and optical properties of Ta$_{2}$/O$_{5}$ thin films as the insulators in DRAM capacitors were studied. Liquid Ta/sib 2//O sub 5/ were prepared by a sol-gel processing and multiple layers were applied by spin-coating up to thickness of 800$\AA$. At annealing temperature of 300~$600^{\circ}C$ the electrical conduction and specific dielectric constant were discussed the behaivor of carrier were observed by the Thermally Stimulated Current (TSC) at the temperature range of 30~23$0^{\circ}C$. At annealing temperature of 300~$600^{\circ}C$ the samples were found to be amorphous below $600^{\circ}C$ and crystalline over it. The electrical strength was about 2.2 MV/cm at 40$0^{\circ}C$. In spite of noncrystallization over 50$0^{\circ}C$ the increasing of leakage current due to pinholes and increasing creak. The refractive index was obtained maximum (2.2) at 40$0^{\circ}C$. The dielectric constant was obtained maximum(18.6) at 40$0^{\circ}C$. TSC was observed one peak at the temperature range of 30~23$0^{\circ}C$ from sample at 40$0^{\circ}C$. In the case of collecting voltage the peak size is decreased in proportion to collecting voltage and then the peak may be thought carrier to be a ionic space charge.e.

• Proceedings of the KIEE Conference
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• 2007.11a
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• pp.124-125
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• 2007

The composites were fabricated $\beta$-SiC and $TiB_2$ powders with the liquid forming additives of 8, 12, 16[wt%] $Al_2O_3+Y_2O_3$ as a sintering aid by pressureless annealing at $1,650[^{\circ}C]$ for 4 hours. Reactions between SiC and transition metal $TiB_2$ were not observed in the microstructure and the phase analysis of the pressureless annealed SiC-$TiB_2$ electroconductive ceramic composites. The relative density, the flexural strength, the Young's modulus and the Vicker's hardness showed the highest value of 82.29[%], 189.5[MPa], 54.60 [GPa] and 2.84[GPa] for SiC-$TiB_2$ composites added with 16[wt%] $Al_2O_3+Y_2O_3$ additives at room temperature. The relative density of SiC-$TiB_2$ composites was lowered due to gaseous products of the result of reaction between SiC and $Al_2O_3+Y_2O_3$. The electrical resistivity showed the lowest value of 0.012[${\Omega}{\cdot}cm$] for 16[wt%] at 25[$^{\circ}C$]. The electrical resistivity was all negative temperature coefficient resistance (NTCR) in the temperature ranges from 25[$^{\circ}C$] to 700[$^{\circ}C$].

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.12
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• pp.1889-1894
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• 2017

Global automobile manufacturers are developing electric vehicles (EVs) to eliminate the pollutant emissions from internal combustion vehicles and to minimize fossil fuel consumptions for the future generations. However, EVs have a disadvantage of shorter traveling distance than that of conventional vehicles. To answer this shortfall, more batteries are installed in the EV to satisfy the consumer expectation for the driving range. However, as the energy capacity of the battery mounted in the EV increases, the amount of heat generated by each cell also increases. Naturally, a better battery thermal management system (BTMS) is required to control the temperature of the cells efficiently because the appropriate thermal environment of the cells greatly affects the power output from the battery pack. Typically, the BTMS is divided into an active and a passive system depending on the energy usage of the thermal management system. Heat exchange materials usually include gas and liquid, semiconductor devices and phase change material (PCM). In this study, an application of PCM for a BTMS was investigated to maintain an optimal battery operating temperature range by utilizing characteristics of a PCM, which can accumulate large amounts of latent heat. The system was modeled using Dymola from Dassault Systems, a multi-physics simulation tool. In order to compare the relative performance, the BTMS with the PCM and without the PCM were modeled and the same battery charge/discharge scenarios were simulated. Number of analysis were conducted to compare the battery cooling performance between the model with the aluminum case and PCM and the model with the aluminum case only.

• The Transactions of the Korean Institute of Power Electronics
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• v.15 no.2
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• pp.111-118
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• 2010

Recently, LCD TV using LED backlight has a great attention due to its low power consumption, slim construction, mercury free, wide color gamut and fast response. For the uniform brightness of the LCD panel, multi channel LEDs and DC/DC converter for each LED are required in conventional system. Therefore energy conversion efficiency is poor, the system size bulky and the cost of production high. To overcome these above mentioned drawbacks, a new current-balancing multi-channel LED driver is proposed in this paper. It can not only drive multi-channel LEDs with one DC/DC converter but also provide all LEDs with constant balanced current. To confirm the validity of the proposed driver, its operation and performance are verified on a prototype for 46" LCD TV.

• Nuclear Engineering and Technology
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• v.41 no.9
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• pp.1143-1156
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• 2009

The SPACE code that is based on a multi-dimensional two-fluid, three-field model is under development for licensing purposes of pressurized water reactors in Korea. Among the participating research and industrial organizations, KAERI is in charge of developing the physical models and correlation packages for the constitutive equations. This paper introduces a developed wall-to-fluid heat transfer package for the SPACE code. The wall-to-fluid heat transfer package consists of twelve heat transfer subregions. For each sub-region, the models in the existing safety analysis codes and the leading models in literature have been peer reviewed in order to determine the best models which can easily be applicable to the SPACE code. Hence a wall-to-fluid heat transfer region selection map has been developed according to the non-condensable gas quality, void fraction, degree of subcooling, and wall temperature. Furthermore, a partitioning methodology which can take into account the split heat flux to the continuous liquid, entrained droplet, and vapor fields is proposed to comply fully with the three-field formulation of the SPACE code. The developed wall-to-fluid heat transfer package has been pre-tested by varying the independent parameters within the application range of the selected correlations. The smoothness between two adjacent heat transfer regimes has also been investigated. More detailed verification work on the developed wall-to-fluid heat transfer package will be carried out when the coupling of a hydraulic solver with the constitutive equations is brought to completion.

• Journal of the Semiconductor & Display Technology
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• v.22 no.1
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• pp.28-32
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• 2023

Recently, the use of stable lithium nanostructures as substrates and electrodes for secondary batteries can be a fundamental alternative to the development of next-generation system semiconductor devices. However, lithium structures pose safety concerns by severely limiting battery life due to the growth of Li dendrites during rapid charge/discharge cycles. Also, enabling long cyclability of high-voltage oxide cathodes is a persistent challenge for all-solid-state batteries, largely because of their poor interfacial stabilities against oxide solid electrolytes. For the development of next-generation system semiconductor devices, solid electrolyte nanostructures, which are used in high-density micro-energy storage devices and avoid the instability of liquid electrolytes, can be promising alternatives for next-generation batteries. Nevertheless, poor lithium ion conductivity and structural defects at room temperature have been pointed out as limitations. In this study, a low-dimensional Graphene Oxide (GO) structure was applied to demonstrate stable operation characteristics based on Li+ ion conductivity and excellent electrochemical performance. The low-dimensional structure of GO-based solid electrolytes can provide an important strategy for stable scalable solid-state power system semiconductor applications at room temperature. The device using uncoated bare NCA delivers a low capacity of 89 mA h g-1, while the cell using GO-coated NCA delivers a high capacity of 158 mA h g−1 and a low polarization. A full Li GO-based device was fabricated to demonstrate the practicality of the modified Li structure using the Li-GO heterointerface. This study promises that the lowdimensional structure of Li-GO can be an effective approach for the stabilization of solid-state power system semiconductor architectures.

• Journal of the Korean Electrochemical Society
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• v.5 no.1
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• pp.30-38
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• 2002

Disordered carbon and boron-substituted disordered carbons $C_{l-x}B_x(x=0.05,\;0.10,\;0.20)$ were synthesized by Pyrolysis of LPG(liquid Propane gas)and $BCl_3$. Their electrochemical properties as anode materials for Li-ion secondary batteries were then investigated. When PVDF is added to the sample in a weight ratio 5 : 95, the disordered carbon with x=0.00 had the first discharge capacity 374 mAh/g. Its cycling performance was relatively good from the second cycle and it had the discharge capacity 258 mAh/g at the 10th cycle. When PVDF is added to the sample in a weight ratio 5 : 95, the sample with x=0.05 among the samples $C_{l-x}B_x(x=0.05,\;0.10,\;0.20)$ exhibited the largest first discharge capacity 860 mAh/g and discharge capacity 181 mAh/g at the 10th cycle. All the samples had similar cycling performances from the second cycle. The sample $C_{0.90}B_{0.10}$ showed the best electrochemical properties as a anode materials fur Li-ion secondary battery from the view points of the first discharge capacity(853 mAh/g when $10w1.\%$ PVDF is used), cycling performance, discharge capacity(400mAh/g at the 10th cycle when $10wt.\%$ PVDF is used). All the samples showed generally larger charge and discharge capacities when $10wt.\%$ PVDF ratter than $5wt.\%$ PVDF is used. The plateau region in the range of voltage lower than 1.25V becomes larger probably since the structure becomes less disordered by the addition of boron. When boron is added, the charge and discharge capacities decreased suddenly at the second cycle. This may be become only a part of Li are reversibly deintercalated and intercalated and a part of Li which are strongly combined with B are not deintercalated. The increases in charge and discharge capacities are considered to be resulted from the increase in the potential of Li in the boron-added carbons, caused by the strengthening of the chemical bond between the intercalated Li and the boron-carbon host since the boron acts as electron acceptor.

• Journal of Korean Clinical Health Science
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• v.2 no.1
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• pp.1-16
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• 2014

Purpose. For a more efficient hospital management, this study aims to provide basic data so that the hospital management and staff in charge of hospital administration may systematically classify and collect hospital information, by analyzing the ordinary characters of an upper-level general hospital system and its common-type balance sheet, common-type profit and loss statement and financial ratio. Methods. By using information about an upper-level general hospital in C Province, provided by Alio(www.alio.go.kr), a public organization information provision site, Health Insurance Review & Assessment Service(www.hira.or.kr) and Ministry of Health and Welfare(www.mw.go.kr), this study analyzed 3 year's data from 2010 to 2012 and provided basic data by analyzing the ordinary characters of an upper-level general hospital system, and its common-type balance sheet, common-type profit and loss statement and financial ratio. Results. After analyzing the ordinary characters, common-type balance sheet, common-type proft and loss statement and financial ration of this general hospital, based on the 2010 to 2012 data, this study came to the following conclusions. Firstly, out of all the 1,069 hospital staff, there were 272 doctors working for 24 medical departments, out of whom the majority was 33 physicians. Most of the nurses were third-class ones, and about 2,000 outpatients and 600 inpatients on average were treated per day. Secondly, as a result of analyzing the common-type balance sheet, this study discovered that intangible assets out of fixed assets accounted for 41%, the majority, out of which usable and profitable donation asset buildings were of great importance, and the liquid assets increased more in 2012 than 2011. In the financial structure, the ratio of liquid liabilities was over 50% out of all the liabilities in 2012, and the ratio of purchase payables was high as well. The ratio of fixed liabilities reached up to 40%, out of which the retirement benefit appropriation fund was quite high. The capital was over 80%, but the surplus was in a deficit state. Compared to the capital, the ratio of total liabilities was about 90%, which indicates the financial structure of this general hospital was vulnerable. Thirdly, as a result of analyzing the common-type profit and loss statement, this study found out that the medical profits from inpatients were higher than profits from outpatients. The material cost was related to the medical quality of this general hospital, and it was as high as 30% out of the total costs and was about 45% of the labor cost. This general hospital showed 10% in the ratio of non-medical profits, and it seemed because of government subsidies. The ratios of medical profits and current net income were gradually changing for the better in 2012, compared to 2011. Lastly, as a result of analyzing the financial ratio, it was found that the liquidity ratio kept decreasing, from 110.7% in 2010 and 102.0% in 2011 to 77.2% in 2012. Besides, it was analyzed that the liquidity ratio and the net working capital ratio greatly decreased, while the quick ratio and the liquid ratio kept decreasing. Conclusions. 1. It is necessary to take the risk management into more consideration, and particularly, it is needed to differentiate and manage the levels of risk in detail. 2. By considering the fact that investments into hospital infrastructures were mostly based on liabilities, it is needed to deal with the scale of losses when evaluating risks. 3. By reflecting the character that investments into hospital infrastructures were based on liabilities, it is necessary to consider the ratio of ordinary profits as well as the ratio of operating profits to sales, and it is also important to consider sales productivity factors, such as the sales amount per a sickbed, by comparing them with other hospitals. As for limitations of this study, there may be some problems in terms of data interpretation because of the lack of information about the number of inpatients and the number of outpatients per year, which are needed for the break-even point analysis. Besides, to suggest a direction for the improvement of hospital management through analyses, non-financial factors should be reflected, such as the trend of economy, medical policies, and politic backgrounds. However, this study only focused on the common-type balance sheet, common-type profit and loss statement and financial ratio, so this study is actually limited to generalizing all the factors by analyzing public data only.

• Proceedings of the Technology Innovation Conference
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• 1997.12a
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• pp.159-176
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• 1997

This paper deals with demand surveys for big science and technology research facilities and equipments to advance national S'||'&'||'T research infrastructure. We perform surveys thrice based on applied Delphi method on the future demand of big S'||'&'||'T research facilities and equipments among Korean scientists and engineers. We employ the concept of big S'||'&'||'T research facilities and equipments as follows: \circled1 The operating size of it is equivalent to that of an institute or research center, and/or \circled2 The users in various disciplines are many, and/or \circled3 The application areas or spill-over effects are large, and/or \circled4 The scale and scope of research objects is equivalent to that of mega science area such as earth.oceanography.space, and/or \circled5 The expenses for installing and operating it are to be supported by government, and/or \circled5 The facilities are expected as necessary for international joint research, and/or \circled7 It is necessary for promoting creative basic science and developing creative technology. We ask the respondents to answer the following questionnaire: - How to prioritize the equipments according to the degree of importance\ulcorner $\square$ Promotion of basic science and mega science, the development of the technologies to enhance the public welfare, the competitiveness of industrial technologies, the job creation for the S'||'&'||'T personnel, and international cooperation. - Who should be in charge of acquisition and operation of the equipments\ulcorner $\square$ Industry, Government Research Institutes, Academy, ERC and SRC. - When shall we acquire the equipment\ulcorner $\square$ Within 2000, 2002, 2007, 2012, and 2017. - How shall we acquire the equipments\ulcorner $\square$ International Joint Development, Domestic Development, Acquisition from Overseas, - How much will the equipment generate spill-over effects to national competitiveness\ulcorner $\square$ Promotion of basic science, contribution to the economy, supply of S'||'&'||'T personnel, and international cooperation. We suggest the following equipments as prioritized candidates after consulting the officers from MOST, MOE, MIC, MOEN and experts from KBSI and STEPI:(table omitted) where, #1, Korea Advanced Liquid Metal Reactor, #2. 800 MHz Superconduction Fourier-Transform Nuclear Magnetic Resonance Spectrometer, #3. Ion Accelerator, #4. Seismic Test Facility, #5. Transonic Wind Tunnel, #6. Radio Telescope for Very Long Baseline Interferometer, #7. 3000t Universal(or Large Structure) Testing Machine, #8. Compost Facility or Plasma Pyrolysis Facility.