• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1999.04a
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• pp.202-216
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• 1999

To control the motion of building structures under earthquakes their response should be measured first by various sensors and transformed into the control forces using some control algorithms. Of many control algorithms linear quadratic control is widely used as it is easy to implement and analyze. However the algorithms has the disadvantage that it needs the real-time measurements of all state variables(i.e, building's displacements and velocities) which are difficult to achieve for the building structures under earthquakes. Thus the practical algorithms employing output feedback are developed. In this paper LQG algorithm is used for the control of the building model with an active mass driver. The building's acceleration is used to obtain the control gain and the Kalman filter gain. The LQG control strategy is verified with the experimental study on the one-storybuilding model equipped with the active mass driver. This paper demonstrates experimentally the efficacy of the LQG algorithm based on the active mass driver system in reducing the response of seismically excited buildings.

• Journal of Power Electronics
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• v.12 no.5
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• pp.723-730
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• 2012

This paper presents a new ZVS single phase bridgeless (Power Factor Correction) PFC, using an active clamp to achieve zero-voltage-switching for all main switches and diodes. Since the presented PFC uses a bridgeless rectifier, most of the time, only two semiconductor components are in the main current path, instead of three in conventional single-switch configurations. This property significantly reduces the conduction losses,. Moreover, zero voltage switching removes switching loss of all main switches and diodes. Also, auxiliary switch turns on zero current condition. The presented converter needs just a simple non-isolated gate drive circuitry to drive all switches. The eight stages of each switching period and the design considerations and a control strategy are explained. Finally, the converter operation is verified by simulation and experimental results.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.3
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• pp.119-124
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• 2014

In this paper, we propose the active rule system applying with emotional margin for power saving control. The proposed system in this paper is a part of the system which derives smart power saving by adjusting the illuminance using active rules within compromising the user's emotion. For this, we set the specific range of standard illuminance and the lower bound of user's emotional margin of illuminance based on measurements and analysis, and use these data in design of active rules. And then, we design and implement the active rule system using mobile agent. The mobile agent in the proposed system migrates to the destination sensor nodes, acquires and transmits sensor data according to the purpose and needs through the active rules, and directly executes the actions corresponding to the optional events(changed sensor data and/or time etc.). And then, we show the potential applicability of the proposed active rule system in various active sensor network applications through the interaction with the rule base and mobile sensor network middleware system.

• Korean Journal of Community Nutrition
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• v.16 no.3
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• pp.307-314
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• 2011

The purpose of this study is finding the easy way of 4 categories activity level confirmation for estimated energy requirement calculation. Total of 386, 5th and 6th grade primary school students participated. The time spent on 7 kinds of activity were collected for 1 day by the internet program developed. Judged by the activity coefficient, sedentary were 6.7% and 5.1%, low active 33.2% and 40.4%, active 43.8%, and45.5%, and very active 16.3% and 9.0% for boy and girl, respectively. The highest and significant correlation coefficient between activity coefficient and time spent on activities shown were 0.339 in commute activity for boys, and 0.466 in leisure for girls. The sensitivity of the sedentary conformation by commute hour for boys was 0.79, and that of very active was 0.56. The sensitivity of the sedentary conformation by leisure hour for girls was 0.67, and that of very active was 0.63. The sensitivity of low active and active by 7 different types of activity was quite low, 0.04~0.37. The exact agreement of activity level conformed by easy way developed was 30.8% and 33.7%, for boys and girls, respectively. More accurate way to identify 4 categories activity level needs to be developed, especially sensitive to conformation of low active and active levels.

• The KIPS Transactions:PartC
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• v.10C no.4
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• pp.413-422
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• 2003

An active network is a new generation network based on a software-intensive network architecture in which applications are able to inject new strategies or code into the infrastructure for their immediate needs. Therefore, the secure active node architecture is needed to give the capability defending an active node against threats that may be more dynamic and powerful than those in traditional networks. In this paper, a security enforcement engine is proposed to secure active networks. We implemented an operating engine with security, authentication and a authorization modules. Using this engine, it is possible that active networks are protected from threats of the malicious active node.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.11a
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• pp.282-286
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• 2000

In this paper, magneto-rheological(MR) damper is studied for vibration control of large infra structures under earthquake. Generally, active control devices need a large control force and a high power supply system to reduce the vibration effectively. Large and miss tuned control force may induce the dangerous situation such that the generated large control force acts to amplify the structural vibration. Recently, to overcome the weaknesses of the active control, the semi-active control method is suggested by many researchers. Semi-active control uses the passive control device of which the characteristics can be modified. Control force of the semi-active device is not generated from the actuator with power supply. It is generated as a dynamic reaction force of the device same as in the passive control case, so the control system is inherently stable and robust. Unlike the case of passive control, control force of semi-active control is adjusted depending on the measured response of the structure, so the vibration can be reduced more effectively against various unknown environmental loads. Magneto-rheological(MR) damper is one of the semi-active devices. Dynamic characteristics of the MR material can be changed by applying the magnetic fields. So the control of MR damper needs only small power. Response time of MR to the input voltage is very short, so the high performance control is possible. MR damper has a high force capacity so it is adequate to the vibration control of large infra structure. Because MR damper has a nonlinear property, normal control method used in active control may not be effective. Clipped optimal control, modified bang-bang control etc. have been suggested to MR damper by many researchers. In this study, sliding mode fuzzy control(SMFC) is applied to MR damper. Genetic algorithm is used for the controller tuning. To verify the applicability of MR damper and suggested algorithm, numerical simulation on the aseismic control is carried out. Simulation model is three-story building structure, which was used in the paper of Dyke, et al. The control performance is compared with clipped optimal control. The present results indicate that the SMFC algorithm can reduce the earthquake-induced vibration very effectively.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.2
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• pp.315-322
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• 2008

Titanium and its alloys have excellent corrosion resistance, high strength to weight ratios and creep properties in high temperature, which make them using many various fields of application. Especially, pure titanium, which has outstanding resistance for the stress corrosion cracking, crevice corrosion, pitting and microbiologically influenced corrosion, brings out to the best material for the heat exchanger, ballast tank, desalination facilities, and so on. Responding to these needs, welding processes for titanium are also being used GTAW, GMAW, PAW, EBW, LBW, resistance welding and diffusion bonding, etc. However, titanium is very active and highly susceptible to embrittlement by oxygen, nitrogen, hydrogen and carbon at high temperature, so it needs to shield the weld metal from the air and these gases during welding by non-active gas. In this study, it was possible to get sound beads without humping and spatter with a decrease of peak power according to increase of pulse width, change of welding speed and overlap rate for heat input control, and shield conditions at pulsed laser welding of titanium plates for Lap welding.

• Journal of Families and Better Life
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• v.23 no.6 s.78
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• pp.15-23
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• 2005

This study was conducted to understand the current leisure activities and needs for future activities among middle-aged men and women. A questionnaire survey was conducted with participants in their forties and fifties of age, who were residing in a large city.'rho survey consisted of questions on current leisure activities, leisure satisfaction, and needs for future activities. Frequency, percentage, average, consisted and Chi-square tests were used for data analysis. The results of this study are as following; First, leisure activities are necessary to enhance the quality of life in terms of spiritual and psychological stability and physical health. Second, the participants are generally not satisfied with their current leisure situations, because of insufficient leisure time, high cost, and shortage of facilities and programs. Third, current leisure behaviors of the participants are restrictive and passive. However, they show a desire to engage in diverse forms of leisure including active and participant leisure activities in the future. Fourth, they wish to perform active and participant leisure activities (for example, indoor sports, continuing education, and taking walks) at places that are close to their residence in the future.

• Journal of the Korea Fashion and Costume Design Association
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• v.18 no.4
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• pp.1-15
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• 2016

The object of this study is to find out the influence of college students' consumption value on consumer attitudes towards environmental awareness and clothing environmental behavior. Questionnaires were administered to 236 college students living in DaeguCity and Kyoungbuk province. Frequency, factor analysis, reliability analysis, regression analysis, and t-test were used for data analysis. Our findings are as follows. Consumption value of college students had factors as differentiated, consumption needs, utility, economies ostentation, others awareness, and belonging. Consumer attitudes towards environmental awareness were found as environmental importance, environmental product purchase, environmental product interest, and environmental action. Clothing environmental behavior were found as up cycle, buying eco-friendly clothing, active participation, saver purchase, and eco-friendly clothing management. The result of this study showed differentiated, others awareness, and belonging had significant effect of environmental product purchase and consumption needs, utility, and belonging had significant effect of environmental action. Differentiated, and others awareness had significant effect of up cycle, buying eco-friendly clothing, active participation, and eco-friendly clothing management. Gender of college students showed significant differences consumption value, consumer attitudes towards environmental awareness, and clothing environmental behavior.

• Journal of Fashion Business
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• v.19 no.4
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• pp.168-182
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• 2015

The purpose of this study is to classify students' attitudes towards uniform modification and analyze their subjective experience regarding appearance, and body satisfaction. Questionnaires were administered to 369 middle and high school girls living in Deagu Metropolitan City. Frequency, factor analysis, reliability analysis, correlation analysis, ${\chi}^2$-test, and t-test are all used for data analysis. Our findings are as follows. Two hundred thirty students (62.3%) agreed to modify their school uniforms to express their personalities and follow fashion trends. Motives for uniform modification had to do with social life, physical attractiveness, and practicality. Attitudes toward appearance are found to be shaped by appearance internalization, active management of appearance, appearance needs, social recognition, and conformity. The motives for uniform modification reveal a significant correlation with attitudes toward appearance. Uniform modification satisfaction differed depending on sub-variables of attitude toward appearance(active management of appearance, personalized appearance needs, social recognition, and body satisfaction, such as satisfaction with height and BMI). There was a significant difference in expression of intention for future plastic surgery depending on body image.