• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1999년도 가을 학술발표회 논문집
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• pp.185-192
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• 1999

This paper presents the results of a parametric study on the behavior of tunnel face reinforced with horizontal pipes. A three-dimensional finite element model was adopted in this study to capture the three-dimensional nature of tunnel face behavior under various boundary conditions. A parametric study was peformed on a wide range of boundary conditions with emphasis on the effect of reinforcing layouts on the deformation behavior of tunnel face. The results of analysis such as tunnel face deformation behavior under various conditions were thoroughly analyzed, and a database for the behavior of tunnel face under different reinforcing conditions was established for future development of a semi-empirical design/analysis method for the tunnel face reinforcing technique. The results indicated that there exits an optimum reinforcing layout for a given tunnel condition, which must be selected with due consideration of tunnel geometry and ground condition.

• 노동경제논집
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• 제31권2호
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• pp.103-128
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• 2008

본 연구는 "한국노동패널조사" 자료를 사용하여 노동조합이 임금에 미치는 효과를 패널 분석하였다. 횡단면 분석을 통하여 구한 노동조합이 임금상승에 미치는 효과는 약 4.6%로 추정되었다. 고정효과 모델을 통하여 추정된 노조의 임금상승효과는 약 2.1%로 상당히 그 효과가 감소하였음을 알 수 있다. 따라서 보이지 않는 근로자의 특성과 노조가 있는 기업에 종사하며 노동조합에 가입하는 의사결정과 양(+)의 상관관계가 존재함을 유추해 볼 수 있으며 기존의 횡단면 분석의 연구 결과가 상당 부분 상향 편의되었음을 유추해 볼 수 있다.

• 한국안전학회지
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• 제22권5호
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• pp.21-26
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• 2007

The computer program is developed to simulate the evacauation time for a building which is made geometrically complex. The program is intended for use both as a search and a design tool to analyze the evacuation safety through a wide range of structure environments. The computer program has a function of importing FDS's result to each individual resident in the building. These attributes include a walking speed reduction by producing visibility reduction for each person on the fire. $A^*$ pathfinding algorithm is adopted to calculate the simulation of escape movement, overtaking, route deviation, and adjustments to individual speeds due to the proximity of crowd members. Finally, a case study for a theater is presented to compared the calculated evacuation time with SIMULEX in detail. This program contribute to a computer program that evaluates the evacuation time of individual occupants as they walk towards, and through the exits especially for building, underground spaces like a subway or tunnel.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 추계학술대회 논문집
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• pp.265-270
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• 1995

In orthogonal cutting a new approach for modeling of burr formation process when tool exits workpiece is proposed. The approach is based on the rigid-plastic FEM combined with the ductile fracture criterion and the element kill method. The approach is applied to simulate a plane strain cutting process. The results of the FEM are compared with those of the experiment. It is shown that the fracture location and fracture angle as well as cutting force can be predicted using the proposed approach with a good correlation to experimental results.

• 한국정밀공학회지
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• 제14권3호
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• pp.28-34
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• 1997

The side burrs and shape distortion resulting from the micromachining of an array of V-shape microgrooves in fresnel lens mould were experimentally invesigated. The focus of this study is on the influence of depth of cut and prism angle on the burr growing rate. The main experiments were con- ducted on the single prism cutting for the convinient of measuring the burr shape and cutting force. From the observation of the burr shape and burr growing rate, it was found that there exits a critical depth of cut below which the burrs are more or less irregular and weak. But above that critical value, the burrs are re- latively clear and stiff.

• 경영과학
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• 제27권3호
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• pp.33-41
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• 2010

A lot of researches find negative volatility risk premium in options market. We can make a trading profit by exploiting the negative volatility premium. This study proposes negative volatility risk premium hypotheses in the KOSPI 200 stock price index options market and empirically test the proposed hypotheses with intra-day short straddle strategy. This strategy sells both at-the-money call option and at-the-money put option at market open and exits the position at market close. Using MySQL 5.1, we create our database with 1 minute option price data of the KOSPI 200 index options from 2004 to 2009. Empirical results show that negative volatility risk premium exists in the KOSPI 200 stock price index options market. Furthermore, intra-day short straddle strategy consistently produces annual profits except one year.

• 환경위생공학
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• 제15권2호
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• pp.1-9
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• 2000

This research employed a senescence-accelerated mouse(SAM) to explore the possibility that differences exits among the major antioxidants, superoxid dismutase(SOD), in terms of ability to protect such animal treated with Cu, Fe and Mn. To assess the antioxidants function of metal ions on SAM-R/1 and SAM-P/8 were administered with Cu, Fe and Mn orally. The effect of metal ions on SAM towards reversing oxygen sensitivity was determined as a bioassays of SOD in the mouse liver. The data show that the SOD activity was induced by each metal ions in both SAM-R/1 and SAM-P/8. It suggested that induced SOD by each metal ions may protect against oxidative mediated stress. Finally, overall data lead to the possibility of metal ions as an antioxidants or each metal ions act producer of oxygen radicals in the liver of SAM-R/1 and SAM-P/8.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.548-552
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• 2005

In most physical processes, the transfer function includes a time-delay, and in the general distributed control system using a computer network, an inherent time-delay exists due to the spatial separation between controllers and actuators. Under the circumstance where an input time-delay exits, the system response overshoots and tends to diverge. For this reasons described above, a controller design method is proposed for a discrete nonlinear system including input time-delay, which adopts the time-discretization using Taylor series. Controllers are synthesized using an input/output linearization method. Finally, several cases of the computer simulations were conducted, and the results validate the proposed methods.

• 통상정보연구
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• 제8권4호
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• pp.343-368
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• 2006

The rapid expansion of regionalism has resulted in the creation of blocs of the global economy, so that those countries not belonging to one or more blocs can be discriminated. The purpose of this paper is to examine the competition policy theoretically, international background with issues, and discussion trend of global enterprise. By doing them, this paper suggests the responsive plan, future prospects, and policy directions for the competition policy by distribution service. There is not a statistically significant relationship between international diversification strategy and firm performance. However, we observed some tendency that the larger the firm size, the higher the firm performance, assuming the degree of international diversification or multinationality to be constant. However, the export productivity increase after 1~2 years, and there exits a clear evidence that the innovation investment increases a firm's export competitiveness as time goes on.

• Journal of Information Technology Applications and Management
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• 제10권2호
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• pp.1-18
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• 2003

Recently, e-business has very much attention in the management fields because it is expected to fundamentally change the way many business compete. Business that don't understand the changes and that can't change their operating model in time will be at a disadvantage. Information technology infrastructure and its management are key components of e-business The purpose of this study was to investigate the effects of information technology infrastructure and its management to the type of information systems used and the use of e-business. A total of 56 Korean firms responded to the survey instrument. There was indirect effect to the use of e-business from the information technology structure via communication capacity and direct effect from management type. The study also found that firms with less centralized forms of information technology were more frequent users of e-business, Firms that have more freedom in information technology decision making tended to be users of the new technology and take advantage opportunities that exits on the information technology.