• Publications of The Korean Astronomical Society
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• v.8 no.1
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• pp.163-168
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• 1993

At intermediate mass transfer rates, accretion disks in binary star systems undergo a thermally-driven limit cycle instability. This instability leads to outburst episodes when the disk is bright and the flow through the disk is rapid separated by long intervals when the disk is dim and the flow through it is low. This intrinsic outburst mechanism can help to understand a wide range of astrophysical phenomena from dwarf novae to soft X -ray transients involving white dwarf, neutron star, and black holes. and to a deeper understanding of the mechanism of angular transport and viscosity in the accretion disk.

• Journal of the Korean Geotechnical Society
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• v.27 no.10
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• pp.55-67
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• 2011

The shear load distribution and deformation of offshore friction piles are investigated using experimental tests and a numerical analysis. Special attention is given to the soil-pile interaction of axially loaded pile. A framework for determining the f-w curve is proposed based on both theoretical analysis and experimental load test data base. A numerical analysis that takes into account the proposed f-w curves was performed for major parameters on pile-soil interaction such as the pile diameter, the pile length, and the soil condition. Based on the analysis, it is shown that the proposed f-w method is capable of predicting the behavior of a friction pile in deep soft clay. Through comparisons with case histories and finite element results, it is found that the proposed f-w curves are more appropriate and realistic m representing the pile-soil interaction of axially loaded piles in deep soft clay than that of existing f-w method.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.165-165
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• 2014

In this study, we demonstrated that the soft lithographic patterning processing of chemical vapor deposition (CVD) graphene and rGO sheets as large scale, low cost, high quality and simplicity for future industrial applications. Recently, a previous study has reported that single layer graphene grown via CVD was patterned and transferred to a target surface by controlling the surface energy of the polydimethylsiloxane (PDMS) stamp [1]. Using this approach, the surface of a relief-patterned elastomeric stamp was functionalized with hydrophilic dimethylsulfoxide (DMSO) molecules to enhance the surface energy of the stamp and to remove the graphene-based layer from the initial substrate and transfer it to a target surface [2]. Further, we developed a soft lithographic patterning process via surface energy modification for advanced graphene-based flexible devices such as transistors or simple and efficient chemical sensor consisting of reduced graphene oxide (rGO) and a metallic nanoparticle composite. A flexible graphene-based device on a biocompatible silk fibroin substrate, which is attachable to an arbitrary target surface, was also successfully fabricated.

• Archives of Reconstructive Microsurgery
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• v.13 no.2
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• pp.123-129
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• 2004

Lower extremity injuries are frequently accompanied with large soft-tissue defects. Such Injuries are difficult to manage for its poor vascularity, rigid tissue distensibility, easy infectability and a relatively long healing period. Also, osteomyelitis, and/or non-union of the fractured bones are relatively common in lower extremity injuries and its weight-bearing role should be considered. Therefore, it is important to select appropriate reconstruction method of the lower extremities, which is applicable to a variety of surgical techniques according to these considerations. The goal of flap coverage in the lower extremity should not only be satisfactory wound coverage, but also acceptable appearance and minimal donor site morbidity. In this article, we have tried to establish a reconstruction method in the lower extremity based on our experiences and clinical analysis of soft tissue reconstruction using free muscle flap transfer in 27 cases from Jan. 2000 to Dec. 2002. The results showed 96% flap survival, and flap failure noted in one of the cases due to vascular insufficiency. In conclusion, we believe that in cases of lower extremity soft-tissue defects especially with open comminuted fractures and infections, muscle free flaps should be considered as the first line of treatment.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.16 no.1
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• pp.18-26
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• 2004

In order to accelerate the rate of consolidation settlement, to reduce settlement, and to increase bearing capacity for soft ground under quay, sand compaction pile method (SCP) has usually been applied. SCP-reinforced ground is composite soil which consists of the sand pile and the surrounding soft soil. One of main important considerations in design and analysis for SCP-reinforced soils is stress concentration ratio according to area replacement ratio. In this paper, the numerical analysis was conducted to investigate characteristics of stress concentration ratio in composite ground. It was found that stress concentration ratio of composite ground is not constant as well as depends on several factors such as area replacement ratio, depth of soft soil, and consolidation process. The values of stress concentration ratio increase during loading stage due to stress transfer of composite soil, and reach up to 2.5∼12 according to area replacement ratio at the end of construction. After the end of consolidation, however, these values are converged to 2.5 to 6.0 irrespective of area replacement ratio due to increase in effective stress of soft soil during consolidation process.

• Journal of Institute of Control, Robotics and Systems
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• v.20 no.2
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• pp.143-148
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• 2014

Conventional wireless power transfer methods based on coupled magnetic fields need a complex winding structure on the surface of the energy transfer and shows poor efficiency near metal objects due to the eddy current effect. In this study, to mitigate these problems, we investigate an electric field-coupled power transmission system, which is less prone to metal object problems and EMI. Because of the fundamental physical limit in the size of link capacitances, a half-bridge converter with an impedance matching transformer is proposed and the design procedure is derived to provide a soft-switching scheme. Hardware implementation shows that the proposed scheme with a pair of 10cm by 10cm copper plate can power a 1.4W USB FAN in a separation of 0.2mm by using insulating paper when driven by 227 kHz gate pulse.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.392-395
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• 2003

In the maritime container terminal, LMTT (Linear Motor-based Transfer Technology) is horizontal transfer system for the yard automation, which has been proposed to take the place of AGV (Automated Guided Vehicle). The system is based on PMLSM (Permanent Magnetic Linear Synchronous Motor) that is consists of stator modules on the rail and shuttle car (mover). Because of large variant of mover's weight by loading and unloading containers, the difference of each characteristic of stator modules, and a stator module's trouble etc., LMCPS (Linear Motor Conveyance Positioning System) is considered as that the system is changed its model suddenly and variously. In this paper, we will introduce the soft-computing method of a multi-step prediction control for LMCPS using DR-FNN (Dynamically-constructed Recurrent Fuzzy Neural Network). The proposed control system is used two networks for multi-step prediction. Consequently, the system has an ability to adapt for external disturbance, cogging force, force ripple, and sudden changes of itself.

• Journal of Electrical Engineering and Technology
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• v.11 no.6
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• pp.1656-1663
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• 2016

A capacitive wireless power transfer (C-WPT) system uses an electric field to transmit power through a physical isolation barrier which forms a pair of ac link capacitors between the metal plates. However, the physical dimension and low dielectric constant of the interface medium severely limit the effective link capacitance to a level comparable to the main switch output capacitance of the transmitting circuit, which thus narrows the soft-switching range in the light load condition. Moreover, by fundamental limit analysis, it can be proved that such a low link capacitance increases operating frequency and capacitor voltage stress in the full load condition. In order to handle these problems, this paper investigates optimal design of double matching transformer networks for C-WPT. Using mathematical analysis with fundamental harmonic approximation, a design guideline is presented to avoid unnecessarily high frequency operation, to suppress the voltage stress on the link capacitors, and to achieve wide ZVS range even with low link capacitance. Simulation and hardware implementation are performed on a 5-W prototype system equipped with a 256-pF link capacitance and a 200-pF switch output capacitance. Results show that the proposed scheme ensures zero-voltage-switching from full load to 10% load, and the switching frequency and the link capacitor voltage stress are kept below 250 kHz and 452 V, respectively, in the full load condition.

• Journal of the Korea Fashion and Costume Design Association
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• v.20 no.2
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• pp.47-62
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• 2018

This study examined recycled fashion design utilizing natural images for application to recent trends. This study is significant in that it presents the possibility of the development of recycled women's wear design by reflecting the characteristics and expressions of natural images and using denim material, which is the most common clothing material for everyday life. The results of this study are summarized as follows. First, five types of women's clothing was produced, pursuing a natural design with a soft and feminine silhouette. Second, the colors used were blue and white, which could represent nature. Third, as for materials, this study used clothing that was to be thrown away: four pairs of denim pants and two denim dresses. This study chose denim cloth, with its great value for reuse, because of the characteristics of the strong and durable fiber, because everyone has more than one article of clothing made from denim and because it can be easily sourced. Fourth, for textile motifs, this study expressed a peaceful natural scenery with tropical animals and plants. In addition, this study further emphasized natural images using transfer media printing. This study has significance in that it presented the possibility of recycled fashion design and expanded the range of utilization using transfer media printing, a dyeing treatment to reduce the environmental burden.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.58 no.3
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• pp.276-284
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• 2009

In this paper, we develop the image transfer remote maintenance monitoring system for hand held device which can compensate defects of human mistake. The human mistakes always happen when the worker communicate information each other to check and maintenance the equipment of the power plant under bad circumstance such as small place and long distance in power plant. A worker couldn't converse with other when in noisy place like Power plant. So, we make some hand device for handy size and able to converse in noisy place. The developed system can have improvement of productivity through increasing plant operation time. And developed system is composed of advanced H/W(hard ware) system and S/W(soft ware)system. The H/W system consist of media server unit, communication equipment with hand held device, portable camera, mike and head set. The advanced s/w system consist of data base system, client pc(personal computer) real time monitoring system which has server GUI(graphic user interface) program, wireless monitoring program and wire ethernet communication program. The client GUI program is composed of total solution program as pc camera program, and phonetic conversation program etc.. We analyzed the required items and investigated applicable part in the image transfer remote maintenance monitoring system with hand held device. Also we investigated linkage of communication protocol for developed prototype, developed software tool of two-way communication and realtime recording skill of voice with image. We confirmed the efficiency by the field test in preventive maintenance of plant power.