• The Transactions of the Korean Institute of Power Electronics
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• v.22 no.2
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• pp.159-165
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• 2017

Small-signal modeling and controller design methodology are proposed to improve the dynamics and stability of a DC-DC dual active bridge (DAB) converter. The state-space average method has a limitation when applied to the DAB converter because its state variables are nonlinear and have zero average values in a switching period. Therefore, the small-signal model and the frequency response of the DAB converter are derived and analyzed using a generalized average method instead of conventional modeling methods. The design methodology of a lead-lag controller instead of the conventional proportional-integral controller is also proposed using the derived small-signal model. The accuracy and performance of the proposed small-signal model and controller are verified by simulation and experimental results with a 500 W prototype DAB converter.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.7 no.6
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• pp.102-109
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• 1998

As the fundamental study of an active suspension system, computer simulation is performed using a quarter model. Design data for the development of active suspension system are presented through performance estimation of active control laws in the time and frequency domain. The verification of compromise between ride quality and handling characteristics is carried out.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.811-815
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• 2005

Traditional passive suspension has limitations to meet the required specifications of high level trains, and so Active suspension system is proposed to meet the requirements with active components which could be controlled by external signal for optimized behavior of train. Active suspension is to be divided by Full active suspension and Semi-active suspension whether using the external power source or not, and though the performance of Semi-Active suspension is worse than Full one. Semi-active suspension is focused with its effectiveness per cost. Semi-Active suspension system consists of sensors, ECU (electrical control unit), and variable damper, which are to be designed to be fit for train system. And the software of ECU is to be developed for to be suited to its dynamic behavior through simulation result calculated by proven model. In this experimental study, the hardware and software of semi-active suspension system is to be realized and its performance for improvement of ride quality to be confirmed through roller rig test.

• Fashion & Textile Research Journal
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• v.17 no.4
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• pp.604-612
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• 2015

This study investigates preferred bicycle wear designs that can satisfy active senior consumers. A survey was conducted on 50-60's women who periodically rode bicycles. The results indicated a preference for slim designs and red colors. Jacket designs preferences were for a tight fit for size tolerance, stand collar style, and elastic band details for cuff styles. Pants design preferences were for a whole band waist belt type with a tight fit style such as leggings in pants silhouette, zipper details on the side line and ankle length. They also preferred styles with pads attached to underpants in the pad style and the part of the back waist in the pocket position. The survey showed four kinds of jacket design drawings on an ordinal scale rating. Results indicated a preference for set-in variation jackets with the red and gray color combination. Finally, we demonstrated bicycle wear design suggestions. The jacket applied different armhole line colors connected to the sleeve to make the waist slimmer; in addition, stretchable material helped improve armpit part functionality.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.85-92
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• 2007

This paper presents a design optimization of a new Advanced Active Blade Twist (AATR-II) blade incorporating single crystal Macro Fiber Composites (MFC) and conducts vibratory loads reduction analysis using an obtained optimal blade configuration. Due to the high actuation performance of the single crystal MFC, the AATR blade may reduce the helicopter vibration more efficiently even with a lower input-voltage as compared with the previous ATR blades. The design optimization provides the optimal cross-sectional configuration to maximize the tip twist actuation when a certain input-voltage is given. In order to maintain the properties of the original ATR blade, various constraints and bounds are considered for the design variables selected. After the design optimization is completed successfully, vibratory load reduction analysis of the optimized AATR-II blade in forward flight condition is conducted. The numerical result shows that the hub vibratory loads are reduced significantly although 20% input-voltage of the original ATR blade is used.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.25 no.10
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• pp.667-676
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• 2015

Working displacement variation by elastic deformation of active Gurney flap which was operated on high frequency was observed. Flap-wise natural frequency was lower than mode analysis result and hinge boundary condition was identified to be the cause through the simple modal test. Design modification for increasing natural frequency was conducted for minimizing the elastic deformation at maximum 35 Hz operating condition which was design requirement condition. Brass bushing was applied instead of rotating bearing for gap minimization and Gurney flap design modification was conducted to increase of the flap-wise natural frequency. Design modification effect was validated by natural frequency comparison with mode analysis result and modal test result of design modification model.

• Educational Technology International
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• v.12 no.1
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• pp.67-94
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• 2011

The major concern of e-learning environment design is to create and improve artifacts that support human learning. To facilitate effective and efficient learning, e-learning environment designers focused on the contemporary information technologies. Web 2.0 services, which empower users and allow the inter-transforming interactions between users and information technologies, have been increasingly changing the way that people learn. By adapting these Web 2.0 technologies in learning environment, educational technology can facilitate learners' abilities to personalize learning environment. The main purpose of this study is to conceptualize comprehensively constructs for understanding the inter-transforming relationships between learner and learning environment and mutable learning environments' impact on the process through which learners learn and strive to shape their learning environment. As results, this study confirms conceptualization of four constructs by incorporating aspects of design that occur in e-learning environments with Web 2.0 technologies. First, learner-designer refers to active and intentional designer who is tailoring an e-learning environment in the changing context of use. Second, learner's secondary design refers to learner's design based on the primary designs by design experts. Third, transactional interaction refers to learner's inter-changeable, inter-transformative, co-evolutionary interaction with technological environment. Fourth, trans-active learning environment refers to mutable learning environment enacted by users.

• Membrane and Water Treatment
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• v.9 no.5
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• pp.335-342
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• 2018

Micelle-Enhanced Ultrafiltration (MEUF) is a membrane separation processes that improving ultrafiltration process with the formation of micelles of the surface active agents. Surface active agents are widely used to improve membrane processes due to the ability to trap organic compounds and metals in the treatment of industrial waste water. In this study, surface active agents are used to improve micelle-enhanced ultrafiltration (MEUF) to reduce chemical oxygen demand (COD), total dissolved solid (TDS), turbidity and clogging the membrane in dairy wastewater treatment. Three important operational factors (anionic surface active agent concentration, pressure and pH) and these interactions were investigated by using response surface methodology (RSM) and Box-Behnken design. Results show that due to the concentration polarization layer and increase the number of Micelles; the anionic surface active agent concentration has a negative effect on the flux and has a positive effect on the elimination of contamination indices. pH, and the pressure have the greatest effect on flux. On the other hand, it could be stated that these percentages of separation are in the percentages range of Nano-filtration (NF). While MEUF process has higher flux than NF process. The results have been achieved at lower pressure while NF process needs high pressure, thus making MEUF is the replacement for the NF process.

• Journal of the Korea Fashion and Costume Design Association
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• v.1 no.1
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• pp.53-71
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• 1999

The purpose of this study is to determine the fashion images implied in men's fashion trends and systematize the characteristics of the textile materials used for fashion images, by analyzing men's fashion trends published by Korean fashion information service companies. This study would be meaningful if it can suggest some objective criteria for the characteristics of textile per fashion image. The researcher analyzed the data on the basis of 8 fashion images, which were ethnic, modern, traditional, avant-garde, active, romantic, natural, techno ones. Above men's fashion images were choosed by analyze the some literatures and men's fashion trend information. The data used for this study were information about S/S and F/W men's fashion trends published by Interfashion planning, Samsung fashion Research Center for the period of 1995-2000. The data collected were subject to “content analysis method”. As a result of the analysis, the major images of 1995-2000 were natural, active, traditional, modern, ethnic, avant-garde, techno images, and while such combinations of conflicting images as ethnic/modern, traditional/avant-garde, natural/techno. Other mixed images were ethnic/natural, modern/active, tradional/active, traditional/modern, romantic/modern, ethnic/romantic, traditional/natural, modern/natural, active/natural, active/traditional/natural, etc. The various characteristics of eight men's fashion images were found in color, pattern and textile materials.

• The Journal of Information Systems
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• v.27 no.3
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• pp.81-102
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• 2018

Purpose The purpose of this study is to investigate the reason why smartphone users do not use mobile banking based on Status Quo Bias and to find out whether there is a difference between passive resistance and active resistance. Design/methodology/approach This study made a design of the research model based on Status Quo Bias. SPSS 23.0 and SmartPLS 2.0 were used for the analysis. Multiple group analysis was performed to identify differences between groups. Findings According to the empirical analysis result, this study confirmed that inertia and perceived risk affected smartphone users who do not use mobile banking. According to the type of resistance, the active resistance group(64.2%) was more than the passive resistance group(35.8%), and it was confirmed that there was a difference in the reasons for not using mobile banking between passive and active resistance group. That is, the greatest difference between passive and active resistance groups was found to be perceived risk, which is an assessment of risk.