• Structural Engineering and Mechanics
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• 제58권6호
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• pp.1127-1143
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• 2016

The pounding phenomenon in adjacent structures happens in severing earthquakes that can cause great damages. Connecting neighboring structures with active and semi-active control devices is an effective method to avoid mutual colliding between neighboring buildings. One of the most important issues in control systems is applying online control force. There will be a time delay if the prose of producing control force does not perform on time. This paper proposed a time-delay compensation method in coupled structures control, with semi-active Magnetorheological (MR) damper. This method based on Newmark's integration is adopted to mitigate the time-delay effect. In this study, Lyapunov's direct approach is employed to compute demanded voltage for MR dampers. Using Lyapunov's direct algorithm guarantees the system stability to design a controller based on feedback. Because of the strong nonlinearity of MR dampers, the equation of motion of coupled structures becomes an involved equation, and it is impossible to solve it with the common time step methods. In present paper modified Newmark-Beta integration based on the instantaneous optimal control algorithm, used to solve the involved equation. In this method, the response of a coupled system estimated base on optimal control force. Two MDOF structures with different degrees of freedom are finally considered as a numeric example. The numerical results show, the Newmark compensation is an efficient method to decrease the negative effect of time delay in coupled systems; furthermore, instantaneous optimal control algorithm can estimate the response of structures suitable.

• 한국지하수토양환경학회지:지하수토양환경
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• 제9권3호
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• pp.27-32
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• 2004

해안가에 발달된 단열암반 대수층에서 수리지질 인자를 추정하기 위하여 조석에 의한 지하수위 변동 현상을 이용하는 조석분석법을 적용하였다. 두 관측정의 지하수위 시계열 자료는 조석에 의한 대수층내 유효응력 전달에 의해 조수위 변동과 비슷한 사인곡선 형태로 나타났다. 교차상관함수를 이용하여 조석과 두 관측정의 지하수위 변동 사이의 개략적인 시간지연을 계산하였으며, 그 결과 심도가 깊은 공의 시간지연이 크게 나타났다. 그리고 조석효율과 시간지연을 계산하여 이들로부터 각각의 저류계수를 추정한 결과 큰 차이를 나타내었다. 본 연구지역에서 실시된 순간충격 시험에 의하여 측정된 저류계수는 조석분석법에서 시간지연을 이용하여 계산한 값과 유사하게 나타나며, 심도가 깊은 공에서 보다 비슷한 값을 나타내고 있다. 조석효율은 피압층에 발달된 균열로 인한 자유면대수층의 영향과 수직적인 지하수 유동에 의해 대수층의 수리상수를 추정하는데 한계가 있는 것으로 사료된다. 따라서 조석분석법은 해안대수층의 수리지질인자를 추정하는데 지하수공의 위치나 대수층의 수리지질적 특성을 고려하여 해석한다면 경제적이고 유용한 방법으로 판단된다.

• 물과 미래
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• 제9권2호
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• pp.76-86
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• 1976

The 30-year design flood hydrograph for the Musim Representative Basin, one of the study basins of the International Hydrological Program, is synthesized by the method of unit hydrograph. The theory of unit hydrograph has been well known for a long time. However, the synthesis of flood hydrograph by this method for a basin with insufficient hydrologic data is not an easy task and hence, assumptions and engineering judgement must be exercized. In this paper, the problems often encountered in applying the unit hydrograph method are exposed and solved in detail based on the theory and rational judgement. The probability rainfall for Cheonju Station is transposed to the Musim Basin since it has not been analyzed due to short period of rainfall record. The duration of design rainfall was estimated based on the time of concentration for the watershed. The effective rainfall was determined from the design rainfall using the SCS method which is commonly used for a small basin. The spatial distribution of significant storms was expressed as a dimensionless rainfall mass curve and hence, it was possible to determine the hyetograph of effective design storm. To synthesize the direct runoff hydrograph the 15-min. unit hydrograph was derived by the S-Curve method from the 1-hr unit hydrograph which was obtained from the observed rainfall and runoff data, and then it was applied to the design hyetograph. The exsisting maximum groundwater depletion curve was derived by the base flow seperation. Hence, the design flood hydrograph was obtained by superimposing the groundwater depletion curve to the computed direct runoff hydrograph resulting from the design storm.

• 한국실천공학교육학회논문지
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• 제4권2호
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• pp.60-66
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• 2012

본 논문에서는 대학에서의 학습의 질을 높이기 위해 지금까지 연구된 많은 이론들을 정리하여, 더 나은 수업을 준비하고 실제로 더 높은 수준의 수업을 듣는데 도움이 되는 학습방법을 제안한다. 대학생들은 대학에 들어와서 자기주도적 학습 방법을 각자 확보하여, 학창시절에 전공 및 중요한 교양 과목을 효과적으로 학습하여야 한다. 그런데 대부분의 대학생들은 저학년일 때 이러한 자기주도적 학습방법을 확보하지 못한 상태에서 고학년으로 진급하게 된다. 그리고 그 때에 가서야 비로서 학습의 중요성을 인지하여 나름대로 학습할려 하지만 이미 학창시절의 상당기간이 지나 우왕좌왕하는 경향이 있다. 본 논문에서는 각종 기존의 각종 학습방법에 대해 소개 및 분석을 하였다. 그리고 학습목적찾기, 시간관리, 수업을 효율적이고 효과적으로 수강하기 위한 수업 준비에 대해 논의하였다. 그리고, 효율적인 학습법의 모델을 제안하였다. 제안한 방법은 각 학생들의 수준과 강의실 환경 등을 고려하여 적절히 선택적으로 적용한다면 효과적인 학습방법이 될 것으로 사료된다.

• 보건교육건강증진학회지
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• 제21권3호
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• pp.87-100
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• 2004

Objective: This research has been conducted in order to conduct sex education using information and communication technologies (ICT) which is currently taught to elementary school students, understand how this method of education affects the knowledge of and attitude towards sexual health in them, so that it could be actually applied in classrooms. Subject: 115 students were divided into three different groups: a comparison group of 38 students (who were given no sex education at all), control 2 group of 39 students (who were given sex education via video programmes), and control 1 group of 38 students (who were given sex education using ICT). Research Tool: A questionnaire used by the literature studies. After verifying content validity, it was modified and supplemented in this way: sex knowledge was reduced to 26, and sex attitude was also reduced to 11. The reliability of the research tool was Cronbach's a=0.86 for sex knowledge tool, and Cronbach's a=0.81 for sex attitude tool. The collected data have been analysed using SPSS 11.0 program. The content validity was analysed by factor analysis and multiple regression analysis, and hypothesis verification was analysed using repeated measure ANOVA test. Result: 1) In sex knowledge marks, there was a significant difference according to the group (p=.009) and point of time (p=.000), and there was a significant interaction between the groups and point of time(P=.000). As a result, it turned out that both video programmes and ICT were significantly effective in improve the knowledge. 2) In sex attitude marks, there were no significant differences according to the group (p=.213), but there was a significant difference according to point of time (p=.002), and there was a significant interaction between the groups and point of time(P=.018). As a result, it turned out that only the education method using ICT was effective in improving the attitude. Conclusion: From the results of this research, it can be said that the sex education using ICT was the most effective method in improving the sex knowledge and attitude of students at elementary school. Therefore, it is advisable that the sex education methods using ICT should be developed and applied continuously.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 추계 학술발표회 제17권2호
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• pp.319-322
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• 2005

When a concrete structure is subjected to load, its response is both immediate and time dependent. Under sustained load, the deformation of a structure gradually increases with time and eventually may be many time greater than its instantanneous value. The gradual development of strain with time is caused by creep and shrinkage. On this study, to estimate of stress variations on time effects in partially prestressed concrete composite girder bridges, computer program applied Age-adjusted Effective Modulus Method(AEMM) in used.

• 디지털산업정보학회논문지
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• 제15권4호
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• pp.63-70
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• 2019

The subject of the simultaneous measuring system of base pattern and deposition pattern is a new research topic on a defect inspection of OLED. In this paper, we propose a new OLED inspection method that simultaneously measures standard and deposition pattern images. This method reduces unnecessary processes and tac time during OLED inspection. For an additional reduction of the tac time during pattern measurement, the ROI was configured to measure only in the designated ROI area instead of measuring the entire area of an image. During the ROI set-up, the value of effective deposition pattern area is included so that if the deposition pattern is out of the ROI zone, it would be treated as a defect before measuring the size and center point of the pattern. As a result, the tac time and inspection process could be shortened. The proposed method also could be applied to the OLED manufacturing process. Production of OLED could be increased by reducing tac time and inspection process.

• 전기학회논문지P
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• 제59권3호
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• pp.340-344
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• 2010

In order to achieve purpose of Smart Grids, which is effective use of electrical energy, the safety of electrical installations must be secured. This paper presented real time monitoring and management method for electrical safety of customer electrical installations connected to Smart Grids. And the direction of electrical safety system for the introduction of real time monitoring and management method was suggested. Efficiency improvement of electrical safety management and new supplementary services related with Smart Girds will be available by introducing the presented method.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제19권2호
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• pp.103-121
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• 2015

In this paper, we briefly review and describe a projection algorithm for numerically computing the two-dimensional time-dependent incompressible Navier-Stokes equation. The projection method, which was originally introduced by Alexandre Chorin [A.J. Chorin, Numerical solution of the Navier-Stokes equations, Math. Comput., 22 (1968), pp. 745-762], is an effective numerical method for solving time-dependent incompressible fluid flow problems. The key advantage of the projection method is that we do not compute the momentum and the continuity equations at the same time, which is computationally difficult and costly. In the projection method, we compute an intermediate velocity vector field that is then projected onto divergence-free fields to recover the divergence-free velocity. Numerical solutions for flows inside a driven cavity are presented. We also provide the source code for the programs so that interested readers can modify the programs and adapt them for their own purposes.

• 대한산업공학회지
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• 제25권3호
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• pp.360-368
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• 1999

We consider the problem of scheduling n jobs with sequence-dependent processing times on a set of parallel-identical machines. The processing time of each job consists of a pure processing time and a sequence-dependent setup time. The objective is to maximize the total remaining machine available time which can be used for other tasks. For the problem, a hybrid genetic algorithm is proposed. The algorithm combines a genetic algorithm for global search and a heuristic for local optimization to improve the speed of evolution convergence. The genetic operators are developed such that parallel machines can be handled in an efficient and effective way. For local optimization, the adjacent pairwise interchange method is used. The proposed hybrid genetic algorithm is compared with two heuristics, the nearest setup time method and the maximum penalty method. Computational results for a series of randomly generated problems demonstrate that the proposed algorithm outperforms the two heuristics.