• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 하계학술대회 논문집 B
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• pp.1041-1043
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• 1993

A robust position control scheme for a Brushless Direct Drive Motor(BLDDM) is presented. To obtain the robustness under the load variation, a Variable Structure Controller(VSC) is used. However, the VSC has a chattering problem and require the full state informations. To overcome this problem, in this paper, the sliding mode observer is used for compensating the load disturbance and estimating the motor velocity. As a result, the VSC for a BLDDM posision control is designed by using only position measurment and the chattering problem is greatly reduced. To show the validaty of the proposed scheme, the simulation study is carried out.

• 아동학회지
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• 제33권3호
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• pp.1-22
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• 2012

The purpose of this study was to examine the relationships between parents' control, affectionate parenting behavior, preschooler's effortful control, prosocial behavior, and cognitive problem-solving ability. The subjects for this study comprised 221 preschoolers (104 boys, 117 girls) and their parents. The major results of this study were as follows. First, parents' effortful control revealed direct effects upon preschooler's effortful control, and affectionate parenting behavior mediated the effects of parents' effortful control upon preschooler's effortful control. Second, preschooler's effortful control mediated the effects of affectionate parenting behavior upon preschooler's prosocial behavior. Third, preschooler's effortful control had direct effects upon prosocial behavior, and prosocial behavior mediated the effects of preschooler's effortful control upon cognitive problem-solving ability. In conclusion, parents' effortful control and affectionate parenting behavior impacted upon preschooler's effortful control. And preschooler's effortful control had an important role upon prosocial behavior and cognitive problem-solving ability.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2003년도 춘계학술발표대회 논문집
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• pp.5-9
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• 2003

Stress and deflection of Active Fiber Composite(AFC) embedded and/or attached composite structures are numerically investigated at the constituent level by the Direct Numerical Simulation(DNS). The DNS approach which models and simulates the fiber and matrix directly using 3D finite elements need to be solved by efficient way. To handle this large scale problem, parallel program for solving piezoelectric behavior was developed and run on the parallel computing environment. Also, the stress result from DNS approach is compared with that from uniform field model.

• Journal of Electrical Engineering and Technology
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• 제10권3호
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• pp.820-831
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• 2015

In a deregulated electricity market, congestion of the transmission lines is a major problem the independent system operator (ISO) would face. Rescheduling of generators is one of the most practiced techniques to alleviate the congestion. However, not all generators in the system operate deterministically and independently, especially wind power generators (WTGs). Therefore, a novel optimal rescheduling model for congestion management that accounts for the uncertain and correlated power sources and loads is proposed. A probabilistic power flow (PPF) model based on 2m+1 point estimate method (PEM) is used to simulate the performance of uncertain and correlated input random variables. In addition, the impact of direct electricity purchase contracts on the congestion management has also been studied. This paper uses artificial bee colony (ABC) algorithm to solve the complex optimization problem. The proposed algorithm is tested on modified IEEE 30-bus system and IEEE 57-bus system to demonstrate the impacts of the uncertainties and correlations of the input random variables and the direct electricity purchase contracts on the congestion management. Both pool and nodal pricing model are also discussed.

• 한국경영과학회지
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• 제8권1호
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• pp.27-30
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• 1983

The purpose of this paper is to find a new method for the warehouse location problem. Akinc and Khumatvala developed a branch and bound algorithm for a one-stage problem, that is, plants and warehouses are at the same location. This paper extends this method to a two-stage problem, that is, plants, warehouses and users are located at different sites, and further this paper allows direct flows from plants to users. The new method is tested at Perkins-Elmer. The test shows that the algorithm is efficient.

• Journal of the Korean Data and Information Science Society
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• 제17권3호
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• pp.991-997
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• 2006

Recently, Liu (2005) proposed a special type of weighting function under a given preference index level with the minimal variability similar to the minimal variability OWA operator weights problem proposed by Fuller and Majlender (2003). He solved this problem using a result of classical optimal control theory. In this note, we give a direct elementary proof of this problem without using any known results.

• 대한가정학회지
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• 제41권7호
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• pp.121-143
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• 2003

The purpose of this study was to show general trends in the psychological environment of family and problem behaviors perceived by adolescents and examine possible changes in such trends in accordance with the individual variables of adolescent, and then find out the effect of these variables on adolescents' problem behavior. The subject were 1374 adolescents of middle school in Busan(male 698, female 676). The main results were as follows : (1) General trends in the degree of parental monitoring showed that girls had more high than boys, and in the degree of family discord, boys showed more high than girls. In the degree of openness of parent-adolescent communication perceived by adolescents showed that girls had more open communication with mother than boys. Such trends in problem behaviors indicated that adolescents had the attention problem most. According to gender, girls had more problems in withdrawal, somatic complain, anxiety/depression, thought problems, attention problems, destructivity/identity, internalizing problems, total behavior problems in comparison to boys. Boys did delinquent behaviors more than girls. (2) For boys, the monthly income of their family, family discord, and the mother-adolescent communication have a significant direct effect on internalizing problems, externalizing problems and total behavior problems. Besides mother's employment and the type of family have a significant indirect effect on behavior problem. For girls, mother's employment, parental monitoring, family discord, and father-adolescent communication have a significant direct effect on internalizing problems. Mother's employment, family discord, mother-adolescent communication have a significant indirect effect on externalizing problems and total behavior problems. Bisides mother's employment, grade, the type of family, dating have a significant indirect effect on behavior problem. (3) The variables to have a significant influence on the parental monitoring showed as the monthly income of their family, dating, mother's employment, the type of family, the family discord showed as mother's employment on the parent-adolescent communication showed as the type of family. (4) Family discord was the most powerful predicator of problem behaviors of middle school students.

• 대한조선학회논문집
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• 제32권3호
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• pp.62-71
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• 1995

비압축성 가정하에 Navier-Stokes 방정식을 이용하여 비정상 점성유동을 수치해석하기 위해서는 매시간 단계에서 타원형 압력 Poisson 방정식의 해를 구해야 하며, 이에 많은 계산시간이 소요된다. 본 논문에서는 직접법을 이용하여 압력 Poisson 방정식을 수치해석하였으며, 분할수 증가에 따른 소요시간 문제를 다루었다. Green 정리를 압력 Poisson 방정식에 적용하면 주어진 문제는 경계치문제로 변환되고, convolution 형의 영역적분은 F.F.T.를 이용하여 계산시간을 단축할 수 있어, 직접법 이용시 소요시간은 경계치문제의 해를 구하는 데에 좌우된다. 직접법의 검증을 위하여 해석해를 알고 있는 경우에 대하여 수치해석하였고, 물체경계조건과 정합문제에 관하여 수치해석 하였는데. 분할수가 (n.n) 시 O($n^{3}$) 미만의 계산시간으로 수치해석할 수 있었다.

• 한국전산응용수학회:학술대회논문집
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• 한국전산응용수학회 2003년도 KSCAM 학술발표회 프로그램 및 초록집
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• pp.17.2-17
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• 2003

The purpose of this paper is to solve the generalized Hyers-Ulam stability problem for a cubic functional equation 8f(x-y/2)＋8f(y-x/2)＋2f(x＋y)=9f(x)＋9f(y) on the basis of a direct method.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.156.2-156
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• 2001

Hypersonic civil airplanes are recently heated up again in USA and Japan, but there are several difficulties when we obtain its optimal trajectories. In this paper, we formulated the trajectory optimization problem as an optimal control problem and solved it by the direct shooting method with the Genetic Algorithm, GA. The result shows it is effective to use this method for the trajectory optimization of the hypersonic flight.