• Journal of the Korea Academia-Industrial cooperation Society
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• v.5 no.2
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• pp.123-127
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• 2004

A printed folded-monopole antenna for portable wireless applications is presented. The proposed design is based on the folded quarter-wave antennas, which have a conductor plate having two arms. A prototype antenna is fabricated according to the simulation result. The obtained antenna can perform in 2.4GHz band and be adopted for laptop applications. All the measurements are performed in the actual test fixture.

• Journal of Korean Society of Environmental Engineers
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• v.38 no.12
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• pp.676-682
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• 2016

In this study, rainwater-greywater hybrid system was installed and operated for 1 year in order to evaluate its water quantity, water quality, and economic efficiency in building no. 39. This system was expected to overcome each disadvantages of and maximize each advantages. Low-greywater that was washed up from shower room was treated by MBR (Membrane Bioreactor) and ozone oxidation. Rainwater that was collected from the rooftop was stored in a reservoir, and then transferred to the storage tank that was mixed with treated greywater. After 1 year operating in building no. 39, rainwater and greywater was used to supply $2,599m^3$ of toilet flushing water. In terms of water quality, rainwater was satisfied far the greywater reuse standards except for E.coli. Moreover, low greywater quality was acceptable except for E. coli, BOD, SS, and turbidity. In addition, economic analysis was obtained from benefit-cost ratio (B/C) with 1.11. It implies that the feasibility of the project was reasonable. Furthermore, various research and policy to improve the economic efficiency of water recycling facilities is required to expand the use of water recycling facilities.

• Environmental and Resource Economics Review
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• v.27 no.2
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• pp.261-286
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• 2018

This paper evaluated the economic feasibility of the life extension of Kori unit 1 and Wolsong unit 1 according to the types of the nuclear power plants (NPPs) and the life extension period comparing to the levelized costs of energy (LCOE) of the new NPPs, coal-fired plants (CFPs), and combined cycle gas turbine (CCGTs) which proposed in the $7^{th}$ Basic Plan for Electricity Supply and Demand. The economic feasibility of the life extension of NPPs using LCOE method is affected by the types of NPPs, lifetime extension periods, discount rate, and capacity factor. According to the analysis results, the pressurized light water reactor (PWR) is more economical than the pressurized heavy water reactor (PHWR). Comparing the economical efficiency between the life extension of NPPs and other alternatives, the operation of the PWR for 20 years is more economical than the one of new NPPs and CFPs. However, 20 years of life extension of PHWR is more economical than the CCGTs, but less economical than new NPPs and CFPs. In summary, the 20 years of life extension of the NPPs seems to be more, especially for the PWR, which is more cost effective than other generation alternatives. Therefore, the government policy of the life extension of NPPs need to be a selective approach that simultaneously considers both safety and economics rather than closing all NPPs.

• Journal of the Korea Convergence Society
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• v.10 no.7
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• pp.243-249
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• 2019

This study is aimed at offering a typology of changes in the social participation of middle-aged and older population and explore determinants for each type of such changes. The data employed for analysis are the 1st survey (2006) through the 6th version (2016) of the Korea Aging Research Panel Survey. Among the respondents of the panel survey, 1,327 males and 1,520 females with a total of 2,847 respondents were analyzed. As a result of applying the growth mixture modelling through the SPS 22.0 and M-plus 8.0 statistical programs, the changes in the social participation of middle-aged and older population have been classified into the 'high-decreasing', 'moderate-increasing' and 'low-stable' trajectory classes. Analysis of the determinants for each class shows that higher the education level, the more likely they are to belong to the high-decreasing and moderate-increasing classes than the low-stable class, and the more the population lives in urban areas, the more likely they are to belong to high-decreasing trajectory class than to low-stable class. Also, it was found that the probability of belonging to moderate-increasing trajectory class was higher than that of the low-stable class when there was no occupation. Through the results of these analyses, the implications of promoting social participation of middle-aged and older population were discussed.

• Journal of the Korea Society for Simulation
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• v.18 no.3
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• pp.23-34
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• 2009

In the railroad rolling stock depot, long-term maintenance tasks is done regularly every two or four year basis to maintain the functionality of equipments and rolling stock body or for the repair operation of the heavily damaged rolling stocks by fatal accidents. This paper addresses the computer simulation model building for the rolling stock maintenance shop for the CDC(Commuter Diesel Car) and Generator Car planned to be constructed at Daejon Rolling Stock Depot, which will be moved from Yongsan Rolling Stock Depot. We evaluated the processing capacity of two layout design alternatives based on the maintenance process chart through the developed simulation models. The performance measures are the number of processed cars per year, the cycle time, shop utilization, work in process and the average number waiting car for input. The simulation result shows that one design alternative outperforms another design alternative in every aspect and superior design alternative can process total 340 number of trains per year 15% more than the proposed target within the current average cycle time.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.560-564
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• 2008

환경부에서는 2000년 3월에 수립 시행된 물 절약 종합대책의 실효성 확보를 위해 시도별로 "물 수요관리 종합계획"을 수립하여 환경부의 승인을 받도록 하였다. 수요관리를 위한 주요 정책 수단은 유수율제고, 절수기기 보급, 수도요금현실화, 중수도 설치, 하폐수처리수 재이용 등이며 2006년까지 서울, 제주도를 제외한 14개 시도에서 물 수요관리 종합계획을 수립하여 승인 받았다. 본 연구에서는 두 가지 측면에서 수요관리 절감량을 평가하고자 하였다. 첫 번째로는 환경부에서 시범평가에 사용하였던 수요관리 수단별 사업추진실적 평가 이외에 지자체에서 절수량을 고려하여 계획하였던 1인 1일급수량 및 유수율과 상수도통계에서 발표된 실제 1인1일급수량 및 유수율 자료를 이용하여 목표달성율을 산정하고 이를 이용해 평가하였다. 두 번째로는 통합수자원평가계획모형인 K-WEAP(Korea-Water Evaluation And Planning System) 모형을 통해 금강권역을 대상으로 사업추진실적 자료 및 절수량 산정식을 사용하여 K-WEAP 모형에서 수요관리 절수량을 산정하고 물수지분석을 수행하여 가용수량을 평가하였다. 수요관리 평가 기반이 구축된 K-WEAP 모형을 통해 여러 시나리오에 따른 수자원 절감가능량 산정 및 정부, 지자체의 수요관리 정책을 평가할 수 있으며 수요관리, 중수도 이용 등 다양한 수자원 보전환경의 변화를 용수수요 추정에 반영할 수 있다. 또한 수요관리 효과 증대방안 향상으로 국가 및 지자체 오염총량관리 계획 및 수자원장기종합계획 수립에 기술적 발전을 도모할 수 있을 것으로 기대된다.

• Fire Science and Engineering
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• v.30 no.4
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• pp.20-26
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• 2016

When the fire takes place in Nuclear Powr Plants(NPPs), the reactor should achieve and maintain safe shut-down conditions and minimize the radioactive material released to the environment. The U.S. Nuclear Regulatory Commission (NRC) has issued numerous generic communications related to fire protection over the past 20 years, after it issued its requirements in the Fire Protection Rule set forth in Title 10, Section 50.48 of the Code of Federal Regulations (10 CFR 50.48) and Appendix R to the 10 CFR 50. The and Nuclear Energy Institute (NEI) has developed a Methodology for Risk Informed Fire Safe-Shutdown Analysis, which is related to the Deterministic Method for Multiple Spurious Operations solutions. The aim of this study was to identify, achieve, and maintain Post-Fire Safe-Shutdown of the Main Control Room (MCR) of the CANDU reactor, even though one train of the multiple Safety Structures, Systems, and Components (SCCs) fail by the technical specification and analysis method.

• Nuclear Engineering and Technology
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• v.27 no.5
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• pp.775-783
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• 1995

This study is to assess the effects of increasing wall thickness on the safety margin of pressure tube in operating and of lowering initial hydrogen concentration on the DHC growth in respect to the improvement of the reliability of pressure tube in CANDU reactors. The pressure tube with thicker wall of 5.2 mm shows much higher safety margin for flaw tolerance by 25％ than the current 4.2mmm tube. The thicker pressure tubes have a great benefit in LBB assessment including the initial crack depth at which DHC occurs, the crack length at onset of leaking and the available time for action. The resistance for the pressure tube ballooning at LOCA accident is also increased with the thicker tube. The calculations for Heq concentration after 20 years of operation as a function of wall thickness and initial hydrogen concentration show that the 5.2 mm nil thickness tube with 5 ppm initial hydrogen concentration is the most resistant to DHC. with the lower initial hydrogen concentration, TSS temperature for the precipitation or hydride decreases and the crack growth during cooldown reduces.

• Nuclear Engineering and Technology
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• v.27 no.2
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• pp.226-233
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• 1995

The wall thickness of a pressure tube is increased in order to reduce the probability of failure in a pressure tube of CANDU type reactor. It is presented here that the variation of wall thickness changes stress, hydrogen concentration and delayed hydride cracking in Zr-2.5Nb pressure tube. When the wall thickness is increased from 4.2 mm to 5.2 mm, the stress exerted on the tube and the deuterium taken up during operation are reduced by 19％. Further, the calculated allowable depth of the surface flaw over which delayed hydride cracking(DHC) is susceptible increases by 50％. DHC initiation is controlled by the stress and by the hydrogen concentration in the pressure tube. The results are therefore very significant in such a respect that increased wall thickness may reduce DHC initiation. Ac the wall thickness increases the hydrostatic tension will increase. Its impact on the acceleration of the crack growth rate of DHC deserves further studies.

• Journal of IKEEE
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• v.23 no.2
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• pp.704-709
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• 2019

In this paper, the electrical characteristics of tunneling field effect transistor(TFET) was studied for different annealing conditions. The TFET samples annealed using hydrogen forming gas(4 %) and Deuterium($D_2$) forming gas(4 %). All the measurements were conducted in noise shielded environment. The results show that subthreshold slope(SS) decreased by 33 mV/dec after annealing process compared to before annealing. Under various temperature range, the noise is improved by average of 31.2 % for 10 atm Deuterium gas at $V_G=3V$ condition. It is also noticed that, post metal annealing with $D_2$ gas reduces the noise by average of 30.7 % at $I_D=100nA$ condition.