• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.136-139
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• 2006

In this paper we propose a small form factor actuator using an inclined motion guide for auto-focusing and zoom motions for mobile information devices. The novel structure using the inclined motion guide and a lens-supporting beam converts the circular motion by an ultrasonic motor into the linear motion of the optical lens. The proposed actuator has a simple structure to minimizing the mechanical tolerance, and the stroke is easy to modify by controlling the inclined angle. Experiments using a prototype verify the validity of the model as small form factor optical actuator.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.13 no.4
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• pp.73-78
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• 2004

The conventional SLT(Shear Lag Theory) which has been proven that it can not provide sufficiently accurate strengthening predictions in elastic regime when the fiber aspect ratio is small. This paper is an extented work to improve it by modifying the load transfer mechanism called NSLT(New Shear Lag Theory), which takes into account the stress transfer across the fiber ends and the SCF(Stress Concentration Factor) that exists in the matrix regions near the fiber ends. The key point of the model development is to determine the major controlling factor among the material and geometrical coefficients. It is found that the most affecting factor is the fiber/matrix elastic modulus ratio. It is also found that the proposed model gives a good result that has the capability to correctly predict the elastic properties such as interfacial shear stresses and local stress variations in the small fiber aspect ratio regime.

• Proceedings of the KIEE Conference
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• 2000.07a
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• pp.245-248
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• 2000

This paper presents the test and operation results of the domestic demonstration of the reactive power compensation device called STATCOM (STATic COMpensator). The object of the paper is to describe the reliability of the unit based on the extensive operation databases. By controlling reactive power, the technology offers utilities the opportunity for increased efficiency and their capabilities will permit transmission planners make the best use of their existing transmission resources STATCOM is a custom power device in a way and can be used in a similar way for the dynamic compensation of power transmission systems, mitigation of voltage flicker and improving the power factor. It is shown that the STATCOM has clear advantages in areas such as: mitigation of voltage flicker and improving power factor.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.9
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• pp.1618-1623
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• 2008

In this paper, a new design method for IMC-PID that adds a phase scaling factor of system identifications to the standard IMC-PID controller as a control parameter is proposed. Based on analytically derived frequency properties such as gain and phase margins, this tuning rule is an optimal control method determining the optimum values of controlling factors to minimize the cost function, integral error criterion of the step response in time domain, in the constraints of design parameters to guarantee qualified frequency design specifications. The proposed controller improves existing single-parameter design methods of IMC-PID in the inflexibility problem to be able to consider various design specifications. Its effectiveness is examined by a simulation example, where a comparison of the performances obtained with the proposed tuning rule and with other common tuning rules is shown.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.11
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• pp.113-122
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• 2011

This paper introduces and develops an efficient method for measuring power factor (PF) and its nature under nonlinear load current situations. The method is based on generating a pulse width modulated signal whose width correlates to the value of PF. This signal can then be employed as a feedback signal for controlling PF related power quantities in a system. This method has the advantages of its simple implementation, less computational complexity, and its allowable error of less than 4[%], which is justified by the computer simulation results.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.846-853
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• 2008

Maglev System is expected to be a new public transportation for future because of its special characteristics. Sleepers of railway role on transferring the lateral load to guideway for Maglev and controlling the distance between rails. Variation of distance of sleepers can affect dynamic responses for maglev guideway. In this paper, Daejon maglev guideway is analyzed to find proper tie spacing of a maglev system. The analysis included using a maglev trainload and also the dead load as the primary forces on bridges. Not only the dynamic behavior of bridges is investigated under sleeper conditions, but also impact factor about vertical displacement on the guideway is produced. This guideway is analyzed in four cases followed by changing spacing of sleeper and then obtained dynamic characteristics such as displacements, acceleration and impact factor by Finite Element Analysis.

• Korean Journal of Human Ecology
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• v.15 no.1
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• pp.31-44
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• 2006

This study examined relationships between children's aggression and the variables such as individual, family, and school adjustment. For this study, individual variables included age, self-esteem, and game-addiction tendency. Family variables included mother's controlling parenting, child-abuse, parents' marital conflict. As for school adjustment, teacher relations, peer relations, classroom and rule adjustment in school were examined. The sample consisted of 642 children of the fifth and sixth grade in Busan. Statistics and methods used for data analysis included frequency, percentage, Cronbach's alpha, factor analysis, two-way Anova, Pearson's correlation, and Hierarchical Regression. Several major results were found from the analysis: First, boys' aggression was higher than girls'. But no age difference was found in children's aggression. Second, game-addiction tendency had a positive correlation with children's aggression. In addition, self-esteem had a negative correlation with boys' aggression. Third, mother's controlling parenting had a positive correlation with children's aggression. Child abuse had a positive correlation with boys' aggression, and parents' marital conflict with girls' aggression. Fourth, teacher relations, peer relations, classroom and rule adjustment in school had a negative correlation with boys' aggression. In addition, rule adjustment in school had a negative correlation with girls' aggression. Fifth, game-addiction tendency, rule adjustment in school, self-esteem, mother's controlling parenting and teacher relations in school were important variables predicting boys' aggression. On the other hand, game-addiction tendency and rule adjustment in school were important variables predicting girls' aggression.

• Korean Journal of Health Education and Promotion
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• v.21 no.4
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• pp.75-97
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• 2004

Objectives: To examine whether the socioeconomic characteristics of communities (contextual effects) are related to the self-rated health of community residents after controlling individual characteristics (compositional effects). Methods: A linked data set including information on individuals from raw data of 1998 Korean National Health and Nutrition Survey(KNHNS) and information on the regions where the individuals lived from the socioeconomic statistical indices of Si-Gun-Gu (city-county-ward) in 1998 was established. The contextual factors of communities were generated from these socioeconomic indices through factor analysis. The contextual effects of community over and above the individual characteristics on the self-rated health were investigated using multilevel analysis. Results: The contextual factors of the community expressed as the factor scores have influence on the self-rated health of their residents above the compositional factors. When the communities were categorized into 5 groups (highest, high, middle, low, lowest) according to each of their factor scores, for factor 1 reflecting urbanization reversely, the residents of the communities that had the high, middle, and low factor scores showed significantly poor subjective health status than the residents of the lowest (most urbanized) group. For factor 2 reflecting community services and health resources, the subjective health status of the residents gradually became poorer when the group went from the highest to the lowest, and the low and lowest groups showed a significant difference. For factor 3 reflecting the manufacturing industry, as compared with the communities that have the highest factor scores, the other 4 groups showed significantly poorer subjective health status. And for factor 4 reflecting the scale of the regional government, as compared with the middle group, the rest of the 4 groups showed significantly better self-rated health. Conclusions: There existed regional contextual effects on their residents' health in Korean adults. To make policies tackling these contextual effects possible, more elaborate researches to find more specific factors and to explain the mechanisms of how health is influenced by the contextual factors are needed.

• Proceedings of the KIEE Conference
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• 1991.11a
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• pp.214-218
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• 1991

This paper presents a PWM controlled cycloconverter with a DC resonant circuit for Induction heating. This cycloconverter converts commercial frequency power to high frequency power directly. So conversion efficiency improved. Controlling a input reactive power regardless of load power, it has sinusoidal input current waveforms as well as a input. displacement factor at 1.

• Proceedings of the KIEE Conference
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• 1990.11a
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• pp.283-286
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• 1990

This paper presents a PWM controlled cycloconverter with a LC resonant circuit for induction heating. This cycloconverter converts commercial frequency power to high frequency power directly. So conversion efficiency improved. Controlling a input reactive power regardless of load power, it has sinusoidal input current waveforms as well as a input displacement factor at 1.