• The Journal of Asian Finance, Economics and Business
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• 제7권8호
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• pp.695-704
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• 2020

Bitcoin and other prominent cryptocurrencies have gained much attention since the last several years. Globally known as digital coin and virtual currency, this cryptocurrency is gained and traded within the blockchain system. The blockchain technology adopted in using the cryptocurrency has raised the eyebrows within the banking sector, government, stakeholders and individual investors. The rise of the cryptocurrency within this decade since the inception of Bitcoin in 2009 has taken the market by storm. Cryptocurrency is anticipated as the future currency that might replace the current paper currency worldwide. Even though the interest has caught the attention of users, many are not aware of its opportunities, drawbacks and challenges for the future. Researches on cryptocurrencies are still lacking and still at its infancy stage. In providing substantial guide and view to the academic field and users, this paper will discuss the opportunities in the cryptocurrency such as the security of its technology, low transaction cost and high investment return. The originality of this paper is on the discussion within law and regulation, high energy consumption, possibility of crash and bubble, and attacks on network. The future undertakings of cryptocurrency and its application will be systematically reviewed in this paper.

• 대한치과보철학회지
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• 제44권2호
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• pp.185-196
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• 2006

Statement of problem: The researches on the influence of design variables on the stress distribution in cortical and trabecular bones and on optimal design for implant system were limited. Purpose: The purpose of this study is to identify the sensitivities of design parameters and to suggest the optimal parameters for designing the onebody type implant system. Material and methods: Stresses arising in the implant system were obtained by finite element analysis using a three dimensional model. An onebody type implant system[Oneplant (Warrantec. Co. Ltd., Korea)] was considered in this study. Vortical load(150 N) was applied on the top of the abutment along the axial direction. The initial design variables set for sensitivity analysis were radius of fixture, numbers of micro thread, numbers of power thread, height of micro thread, future length, tapered angle of future, inclined angle of thread, width of micro thread and width of power thread. The statistical technique of Design of Experiments(DOE) was applied tn the simulation model to deduce effective design parameters on stress distributions in bones. The deduced design parameters were incorporated into a fully automated design tool which is coupled with the finite element analysis and numerical optimization to determine the optimal design parameters. Results: 1. The result of sensitivity analysis showed six design variables - radius of future, tapered angle of fixture, inclined angle of thread, numbers of power thread, numbers of micro thread and height of micro thread - were more influential than the others. 2. The optimal values of design variables can be deduced by coupling finite element analysis (FEA) and design optimization tool(DOT).

• 한국산학기술학회논문지
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• 제4권4호
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• pp.409-417
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• 2003

본 논문에서는 세계적인 추세에 있는 전력산업의 규제완화와 지구규모적인 환경문제, 전기의존도의 증가, 수용가의 다양한 요구 등 배전계통을 둘러싼 환경변화에 대응할 수 있는 차세대 전기에너지공급시스템의(FRIENDS)의 기본개념과 운용모델을 제안하여, 기존계통에의 도입적용에 대한 구체적인 실현형태를 제시한다. 특히, 배전계통의 목표관리로 수행되고 있는 수용가전압의 전압관리 측면에서 FRIENDS의 운용모델과 기존의 전압관리 운용방안을 비교ㆍ평가하는 수법을 제시하여, FRIENDS의 운용효과를 정량적으로 평가한다. 여기서, 차세대 배전계통은 유연하게 계통구성을 변화시킬 수 있고, 수용가에 멀티메뉴 서비스를 제공할 수 있으며, 각종 설비의 고효율운전을 가능하게 하는 고유연ㆍ고신뢰ㆍ고효율 전기에너지유통시스템을 말한다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1992년도 하계학술대회 논문집 A
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• pp.165-168
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• 1992

The ADS system is applied and used in KEPCO. But it is short of graphic functions and on-line display of power system. In this study, we develpoed ADS MMI system which expands graphic functions of ADS, and enhanced efficiency of ADS system. And we showed system extension in the future and suggested a foundation of total distribution automation system.

• 한국초전도ㆍ저온공학회논문지
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• 제16권2호
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• pp.42-46
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• 2014

In this study we investigated ac transport current losses in the face to face stack for the anti-parallel current flow, and compared the electromagnetic properties with those of the single SC tape as well as those of the same stack for the parallel current path. The gap between the SC tapes in the stack varied in order to verify the electromagnetic influence of the neighbors when current flows in opposite direction, and the model was implemented in the finite element method program by the commercial software, COMSOL Multiphysics 4.2a. Conclusively speaking, the loss was remarkably decreased for the anti-parallel current case, which is attributed the magnetic flux compensation between the SC layers due to the opposite direction of the current flows. As the gap between SC tapes was increased, the loss mitigation became less effective. Besides, the current density distribution is very flat cross the sample width for the narrower gap case, which is believed to be benefit for the power electric system. These results are all in good agreement with those predicted theoretically for an infinite bifilar stack.

• 환경위생공학
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• 제5권2호
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• pp.15-21
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• 1990

Current analyses of tap water in Seoul metropolitan area prove the water is still safe, despite the Pollution of raw water source. However, it also significantly suggests that a feasibility study of apply, additional advanced technology to existing water treatment processes is needed in order to cope with future pollution. Also, the monitoring of water quality within private, multi-household buildings is important as the monitoring of public water distribution system.

• 산업기술연구
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• 제29권B호
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• pp.221-228
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• 2009

For a stable supply of electric power, periodical inspection of the electric facilities and repair of the distribution lines are required. In case of any unexpected accidents, looped operation among distribution lines may be necessary in order to supply electricity through the sound lines, separating the faulted lines. As a result of this study, it was found that normal looped operation became impossible when phase difference of the looped distribution lines is more than 3 degrees compared with the voltage supply of the distribution lines. Therefore, for a stable supply of electric power to Chuncheon, it is judged to be desirable that looped operation of the distribution lines coming from the same substation M. Tr Bank shall be performed in principle and in case of looped operation with the substation of different system, looped operation among the lines shall be performed after voltage regulation of the substation M. Tr Bank, maintaining similar voltages and load supply volume in order to avoid phase difference through checking the operation conditions of each substation M. Tr Banks. And when looped operation among the distribution lines is scheduled, voltage regulation schedule has been established so far by calculating maximum supply volume through the transformer of the substation and the maximum load volume through the distribution lines but in the future, looped operation of the distribution lines shall be carried out by removing voltage difference with regulating tap or load of the surrounding transformers, with giving prior notice to the substation operators.

• 한국수자원학회논문집
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• 제55권spc1호
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• pp.1167-1175
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• 2022

본 연구에서는 노후도를 보다 간단히 평가할 수 있는 운영지수 분석법을 개발하였고 이를 기존의 노후도 분석법과 비교 분석하였다. 청주시 상수관망에 적용하여 노후도를 비교 분석하였으며 사용성을 입증하였다. 기존의 간접평가법 분석결과, 율량동(구시가지), 내덕1동, 용암2동 상수관망의 노후도가 가장 높은 것으로 분석되었으며, 신뢰성해석을 통한 안전도 분석 결과 내덕1동 상수관망이 직경 200 mm, 300 mm 강관 모두 파괴확률 3.21%, 4.65%로 안전도가 가장 취약한 것으로 분석되었다. 운영지수 분석법의 경우, 내덕1동 상수관망이 직경 200 mm, 300 mm 강관 모두 위험도 0.2609, 0.2644로 가장 높은 것으로 분석되었으며, 개량 우선순위는 비슷한 것으로 나타났다. 따라서 향후 운영지수 분석법을 통해 상수도관을 보다 간단하게 노후도를 분석하여 상수관망의 운영관리에 활용이 가능할 것으로 판단된다.

• 한국지리정보학회지
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• 제15권1호
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• pp.64-75
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• 2012

미래 산림식생분포의 변화를 전망하기 위해 우리나라의 현재 산림식생분포도를 기준으로 환경변수와 다항로짓모델을 이용하였다. 환경변수는 지형, 최한월온도, 여름평균강수량, 토양염기포화율, 토양유기물함량 자료를 구축하였으며, MIROC3.2 hires A1B 시나리오 자료와 통계적 상세화 기법을 적용하여 미래기후변화시나리오를 구축하였다. 미래 여름강수량은 현재보다 각각 -1.2%, 5.7%, 5.3%로 증가추세였고, 미래 최한월온도는 2020s, 2050s, 2080s에 현재보다 각각 $4.4^{\circ}C$, $6.0^{\circ}C$, $9.4^{\circ}C$ 증가하였다. 미래 여름평균강수량과 최한월온도를 이용하여 미래 산림식생분포변화를 전망한 결과 현재 산림식생분포에 비해 2080s에 미래 활엽수림과 혼효림은 각각 56.9%와 8.3% 증가하고 미래 침엽수림은 11.2% 감소하는 것으로 전망되었다.

• 해양환경안전학회지
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• 제23권3호
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• pp.242-249
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• 2017

In order to develop an HNS safety management system to assess and visualize hazard levels via an automated method, we have conceptualized and configured a sample system. It is designed to quantify the risk of a vessel carrying HNS with a matrix method along navigational route and indicate hazards distribution with a contour map. The basic system which provides a visualized degree of hazards in real time has been introduced for the safe navigation of HNS ships. This is useful not only for decision making and circumstantial judgment but may also be utilized for HNS safety management with a risk base. Moreover, this system could be extended to address the navigational safety of marine traffic as well as of autonomous vessels in the near future if the sensors used are connected with IoT technology.