• 천문학논총
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• 제8권1호
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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.

• 한국지반공학회논문집
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• 제27권10호
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• pp.55-67
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• 2011

일반적으로 연직하중을 받는 말뚝의 주면하중전이 거동 및 변형해석을 위해 f-w 하중전이 해석법이 널리 사용되고 있다. 본 연구에서는 국내 지반조건에 적합한 대심도 마찰말뚝의 주면하중전이 해석을 고찰하였으며, 여러 현장재하시험 자료와 3차원 유한요소해석 및 이론적인 방법 통해 말뚝의 실제 거동에 보다 부합되도록 대심도 마찰말뚝의 f-w곡선을 제안하였다. 제안된 하중전이함수법의 타당성을 검증하기 위하여 현장재하시험 사례와의 비교분석을 수행하였고, 그 결과, 제안된 해석방법은 기존 f-w곡선에 비해 대심도 마찰말뚝의 거동 및 변형 특성을 적절히 예측함을 알 수 있었다. 또한 대심도 마찰 말뚝지반의 상호작용을 정량적으로 평가하기 위하여 주면하중전이거동에 영향을 주는 인자들을 통한 매개변수 연구를 추가로 수행하였다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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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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• 제13권2호
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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.

• 한국해안해양공학회지
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• 제16권1호
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• pp.18-26
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• 2004

SCP공법(Sand Compaction Pile Method)은 안벽구조물 하부 지반이 연약할 경우에 압밀침하 속도를 증가시키고, 침하를 감소시키며, 지지력을 증대시키기 위하여 널리 적용되어 왔다. SCP 개량지반은 연약지반에 타설된 모래말뚝과 주변 연약지반으로 구성된 복합지반을 형성한다. 이와 같은 복합지반의 설계 및 해석 시 가장 중요한 요소는 치환율에 따른 응력분담비이다. 본 연구에서는 수치해석기법을 사용하여 복합지반에 대한 응력분담비 특성을 검토하였다. 치환율에 따른 응력분담비는 상수 값이 아니라 연약지반의 깊이, 압밀과정에 의존한다. 또한 하중재하 단계에 응력분담비는 복합지반의 응력전이 특성에 의하여 증가하며, 재하 완료 직후에는 치환율에 따라 2.5∼12의 값을 가진다. 그러나 과잉간극수압이 소산되어 점토지반의 유효응력이 증가되는 압밀과정 동안에는 감소하여 압밀 완료 후에는 치환율에 관계없이 2.5∼6정도 범위로 수렴한다.

• 제어로봇시스템학회논문지
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• 제20권2호
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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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• 제어로봇시스템학회 2003년도 ICCAS
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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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• 제11권6호
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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.

• 한국의상디자인학회지
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• 제20권2호
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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.

• 전기학회논문지P
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• 제58권3호
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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.