• Proceedings of the KIEE Conference
• /
• 1993.07b
• /
• pp.1041-1043
• /
• 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.

• Korean Journal of Child Studies
• /
• v.33 no.3
• /
• pp.1-22
• /
• 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.

• Proceedings of the Korean Society For Composite Materials Conference
• /
• 2003.04a
• /
• pp.5-9
• /
• 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
• /
• v.10 no.3
• /
• pp.820-831
• /
• 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.

• Journal of the Korean Operations Research and Management Science Society
• /
• v.8 no.1
• /
• pp.27-30
• /
• 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
• /
• v.17 no.3
• /
• pp.991-997
• /
• 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.

• Journal of the Korean Home Economics Association
• /
• v.41 no.7
• /
• pp.121-143
• /
• 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.

• Journal of the Society of Naval Architects of Korea
• /
• v.32 no.3
• /
• pp.62-71
• /
• 1995

In the numerical analysis of incompressible unsteady Navier-stokes equation, large time is required for solving the pressure Poisson equation of the elliptic type at each time step. In this paper, a numerical analysis by the direct method is carried out to solve the pressure Poisson equation and the computing time is analyzed as mesh size increases. The pressure Poisson equation can be transformed to the boundary value problem by the Green theorem. The computing time for the convolution type of the domain integral can be reduced by using F.F.T. and the computing time in the direct method depends entirely on obtaining the solution of the boundary value problem. The numerical analysis on the known solutions is carried out and compared for the verification of the direct method. And the numerical analysis on the body boundary and domain decomposition problem are carried out with the computing time less than O($n^{3}$) in the (n.n) mesh.

• Proceedings of the Korean Society of Computational and Applied Mathematics Conference
• /
• 2003.09a
• /
• pp.17.2-17
• /
• 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
• /
• 2001.10a
• /
• pp.156.2-156
• /
• 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.