• Journal of the Korean Society for Precision Engineering
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• v.28 no.11
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• pp.1259-1264
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• 2011

This paper suggests a new film-type haptic actuator based on cellulose acetate electro-active paper. Conventional tiny haptic actuators in mobile devices can create vibrotactile sensation at only near resonant frequency. The strategy of operating near the resonant frequency, however, brought a new issue for creating vibrotactile sensation which can be strong enough to feel in arbitrary frequency. Another problem is that the size of the conventional actuator is not small enough to be embedded into slim mobile devices. In order to achieve these issues, we propose a thin and tiny actuator based on a cellulose acetate material charged with an electric potential. The motion of the actuator can be a concave or a convex by controlling a polarity of both charged membranes and the actuator performance can be modulated by increasing level of biased electric potential.

• Journal of Information Technology Applications and Management
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• v.22 no.2
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• pp.71-93
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• 2015

Due to the rapid development of information communication technology, employees have conducted their tasks with smart devices such as smartphones and tablet PCs in the midst of after work hours. In line with this phenomenon, we have examined the relationships among technostress, work connectivity behavior after hours (WCBA) and technostress inhibitors and job satisfaction. Based on the results of prior research, we developed and tested our research model which posits the certain factors such as technostress, WCBA and technostress inhibitors affect work-life conflicts which, in turn influence employees' job satisfaction. Survey data collected from 345 users who have experiences on using smart devices was used to test the model using PLS (partial least squares). In this study, we found that technostress and WCBA were positively related to the work-life conflicts. We also found that the relationship between technostress inhibitors and job satisfaction was significant. The implications of these findings for both research and practice are discussed.

• Journal of the Korean Institute of Rural Architecture
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• v.16 no.2
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• pp.19-26
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• 2014

This study aims on the direction of rehabilitation in rural area through the case analysis and policy of Eco-Quartier in France. At this object, this study was preceded with 3 main contents. Firstly, after examined the changes and policy on the rural area in Korea, it has analysed about the problems and changes on the rural residential environment in Korea. Secondly, it has researched about the various methods relative to the rural area development project, the issue on the sustainable development strategy in rural area and the changes of rural ares in France. Lastly, regarding precedent studies, it has analysed the projects in rural area which has selected through the policy of Eco-Quartier in France. The policy and criterions for Eco-Quartier in France, which was examined by this study, has been achieved through reasonable procedure from the superior concepts to detail planning and the guidelines for the project of rural area. This is expected to use as the basic criterions for the sustainable development and planning orientation of rural area in Korea.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.442-449
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• 2004

This paper describes a new concept of finite element analysis, which is based on neural network based material models (NNCMs) without invoking any pre-chosen mathematical framework. NNCMs have several advantages over conventional constitutive models (CCMs) and once plugged in a finite element (FE) engine, can be used for FE analysis in a manner similar to CCMs. The paper demonstrates a FE framework in which NNCMs are incorporated and also proposes a strategy for data enhancement by invoking the assumption of isotropy of the material. It is shown through some illustrative examples that this provides a better training environment for a generalized NNCM in which stress and strain components are used as effects and cause. Form this study, it appears that there is a prima facia case for developing NNCMs for materials for which mathematical theories become too complex and a large number of material parameters and constants have to be identified or determined.

• International Journal of Fluid Machinery and Systems
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• v.1 no.1
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• pp.33-37
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• 2008

EquiMar (Equitable Testing and Evaluation of Marine Energy Extraction Devices in terms of Performance, Cost and Environmental Impact) is one of the first round of energy projects under the European Commissions 7th Framework Programme (FP7). The three year EquiMar project aims to deliver a suite of protocols for the evaluation of both wave and tidal converters, harmonizing testing and evaluation procedures across the wide range of available devices, accelerating adoption through technology matching and improving the understanding of both environmental and economic impacts associated with the deployment of devices. The EquiMar protocols will cover site selection, initial design, scaling up of designs, the deployment of arrays and environmental impact assessment as well as economic issues. EquiMar will build on existing protocols, e.g. UK DTI Marine Renewables Development Fund (MRDF) protocols for wave and tidal energy, and engage with international standards setting activities, e.g. IEC TC114.

• Journal of Mechanical Science and Technology
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• v.15 no.12
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• pp.1808-1815
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• 2001

The characteristics of a pulsed plasma jet originating from an electrothermal capillary discharge have been investigate using laser-induced fluorescence (LIF) measurement. Previous emission measurements of a 3.1 kJ plasma jet show trial upstream of the Mach disk the temperature and electron number density are about 14,000 K and and 10$\^$17/ cm$\^$-3/, while downstream of the Mach dick tole values are about 25,000 K and 10$\^$18/ cm$\^$-3/, respectively. However, these values are barred on line-of-sight integrated measurements that may be misleading. Hence, LIF is being used to provide both spatially and temporally resolved measurements. Our recent work has been directed at using planar laser-induced fluorescence (PLIF) imaging of atomic copper in the plasma jet flow field. Copper is a good candidate for PLIF studies because it is present throughout the plasma and has electronic transitions that provide an excellent pump-detect strategy. Our PLIF results to date show that emission measurements may give a misleading picture of the flow field, as there appeals to be a large amount of relatively low temperature copper outside the barrel shock. which may lead to errors in temperature inferred from emission spectroscopy. In this paper, the copper LIF image is presented and at the moment, relative density of atomic copper, which is distributed in the upstream of the pulsed plasma jet, is discussed qualitatively.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.26 no.2
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• pp.99-103
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• 2020

The volume of parcel delivery is steadily increasing with the rapid growth of the global online e-commerce market. However, a large amount of packaging materials used for these parcel delivery is finally causing environmental problems as waste. In this study, we have taken a pilot test on the returnable parcel delivery packaging & service, which is one of various ways to reduce the generation of the distribution packaging waste raised by e-commerce-based parcel delivery. For the purpose of this project, we made 300 boxes of returnable & foldable delivery packaging(415 mm × 280 mm × 160 mm) and have cooperated with e-commerce company(CJ ENM) & logistics company(LogisAll). Consequently, about 50% of the delivered packages was returned because of the lack of consumer's understanding on the returnable packaging system. We finally have suggested the policy strategy to get over problems derived from the experiment, like the retrieval rate and cost of the returnable packaging, economic efficiency and so on.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.6
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• pp.547-554
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• 2013

This paper proposes a novel formation algorithm of identical robots based on object tracking method using omni-directional images obtained through fisheye lenses which are mounted on the robots. Conventional formation methods of multi-robots often use stereo vision system or vision system with reflector instead of general purpose camera which has small angle of view to enlarge view angle of camera. In addition, to make up the lack of image information on the environment, robots share the information on their positions through communication. The proposed system estimates the region of robots using SURF in fisheye images that have $360^{\circ}$ of image information without merging images. The whole system controls formation of robots based on moving directions and velocities of robots which can be obtained by applying Lucas-Kanade Optical Flow Estimation for the estimated region of robots. We confirmed the reliability of the proposed formation control strategy for multi-robots through both simulation and experiment.

• Korean System Dynamics Review
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• v.12 no.1
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• pp.5-37
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• 2011

This article aims to clarify what is the best investment behavior in Capital Intensive Industries(hereinafter CIIs) which show repeated business cycles. In CIIs, investments is centered in the period of upturns and goes beyond the adequate level because of the time that takes to completion of facilities. This over-investment causes oversupply and downturn, and in period of downturn, investments shrinks under the adequate level. The repeated change of over-investment and under-investment is the reason for the business cycles. In this article, a simulation model replicating the business cycles in CIIs was constructed and the effects of various investment strategies was tested. The results are as follows. First, the investment behavior following market condition causes the ongoing fluctuation of profits. Second, strategic increase in flexibility such as adjustment of facility utilization and shortening of facility construction time contributes to the increase in profit and stabilization of income. Third, in relation to market condition, the constant investment is more profitable in stagnated market and the counter-market investment is more profitable in growing market. In sum, it is desirable not to synchronize their investment with those of competitors.

• The Journal of Korean Physical Therapy
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• v.22 no.6
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• pp.43-51
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• 2010

Purpose: This study examined the influence of visuomotor congruency on learning a relative phase relationship between a single joint movement and an external signal. Methods: Participants (N=5) were required to rhythmically coordinate elbow flexion-extension movements with a continuous sinusoidal wave (0.375 Hz) at a $90^{\circ}$ relative phase relationship. The congruent group was provided online feedback in which the elbow angle decreased (corresponding to elbow flexion) as the angle trajectory was movingup, and vice versa. The incongruent group was provided online feedback in which the elbow angle decreased as the angle trajectory was moving down, and vice versa. There were two practice sessions (day 1 and 2) and each session consisted of 6 trials per block (5 blocks per session). Retention tests were performed 24 hours after session 2, and only the external sinusoidal wave was provided. Repeated ANOVAs were used for statistical analysis. Results: During practice, the congruent group was significantly less variable than the incongruent group. Phase variability in the incongruent group did not significantly change across blocks, while variability decreased significantly in the congruent group. In retention, the congruent group produced the required $90^{\circ}$ relative phase pattern with significantly less phase variability than the incongruent group. Conclusions: Congruent visual feedback facilitates learning. Moreover, the deprivation of online feedback does not affect the congruent group but does affect the incongruent group in retention.