• 한국산업융합학회 논문집
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• 제26권6_1호
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• pp.967-976
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• 2023

Currently, with the thriving development in the field of solar energy, the widespread adoption of solar grid-connected power conversion systems is rapidly expanding. As the market continues to grow, the efficiency of solar power conversion systems is steadily increasing, while prices are rapidly decreasing. Photovoltaic panels often produce low output voltages, and Boost converters are commonly employed to elevate and stabilize these voltages. They are also utilized for implementing Maximum Power Point Tracking (MPPT), ensuring the full utilization of solar power generation. Recently, synchronous control techniques have been introduced, using controllable switching devices like Si IGBT or SiC MOSFET to replace the diodes in the original circuits. However, this has raised concerns related to costs. This paper offers a compromise solution, considering both the performance and economic factors of the converter. It proposes a hybrid high-efficiency synchronous converter structure that combines Si IGBT and SiC MOSFET. Additionally, the proposed topology has been practically implemented and tested, with results confirming its feasibility and cost-effectiveness.

• Journal of Gastric Cancer
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• 제9권4호
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• pp.256-261
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• 2009

목적: 진단 기술의 발전과 함께 위암 환자에서 동시성과 이시성암이 발견되는 빈도가 증가하고 있다. 본 연구에서는 위암에서 발견된 동시성과 이시성암의 임상병리학적 특성과 임상적 의의에 대하여 알아보고자 하였다. 대상 및 방법: 1998년 1월부터 2008년 3월까지 조선대학교병원에서 위암으로 진단된 환자들의 의무기록을 후향적으로 분석하였다. 결과: 1,048명 위암 환자 중 38명(3.6%)에서 동시성과 이시성암이 있었다. 38명 중 16명(42.1%)은 동시성암이었고 22명(57.9%)은 이시성암이었다. 위암과 이차성 원발암 간의 평균 시간간격은 $27.08{\pm}31.25$개월이었다. 가장 흔한 중복암은 폐암(8/38, 21.1%)과 대장암(8/38, 21.1%)이었다. 27명의 환자가 위암에 대하여 수술적 치료를 하였으며 이 중 5명(18.5%)은 동시성암, 22명(81.5%)은 이시성암이었다. 평균 생존 기간은 49.8개월이었으며 동시성암의 경우는 24.6개월 이시성암의 경우는 68.1개월이었고 이들의 3년 생존율은 동시성암, 이시성암 각각 33.3%, 81.1%였다. 결론: 위암에서의 이차성 원발암 진단에 대한 진단에 있어 충분한 수술 전 검사를 통한 동시성암의 발견과 지속적인 추적검사를 통한 이시성암의 발견을 위해 주의를 기울여야 한다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 Proceedings ICPE 01 2001 International Conference on Power Electronics
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• pp.56-59
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• 2001

An effective method of detecting inter-turn short circuits on round rotor windings is described. Shorted-turns can have significant effects on a generator and its performance. A method of detecting inter-turn short circuits on rotor windings is described. The approach used is to measure the rate of change of the air-gap flux density wave when the rotor is at operating speed and excitation is applied to the field winding. The inter-turn short circuits sensor for synchronous generator's field winding has been developed. The sensor, installed in the generator air-gap, senses the slot leakage flux of field winding and produces a voltage waveform proportional to the rate of change of the flux. For identification of reliability for sensor, a inter-turn short circuits test was performed at the West-Inchon combined cycle power plant on gas turbine generator and steam turbine generator. This sensor will be used as a detecting of shorted-turn for field winding of synchronous generator. The purpose of this paper is to describe the design and operation of a sensitive inter-turn short circuits detector. In this paper, development of inter-turn short circuits sensor for field winding of synchronous generator and application in a field.

• 한국중재학회지:중재연구
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• 제19권2호
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• pp.155-178
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• 2009

The ODR can be categorized into four distinctive types. First type is the asynchronous non-demeanour method. Second type is the asynchronous demeanour method. Third type is the synchronous demeanour method. Fourth type is the synchronous demeanour method. A typical example of the asynchronous and non-demeanour method is e-mail. The example of the synchronous and non-demeanour method is tele conference. The example of the asynchronous demeanour method is video recordings. The example of synchronous and demeanour method is video conference. The primary benefit of e-mail is to avoid the physical violence. But the costs of email is the lack of emotional aspects of disputants. The benefits of tele conference is ease of use, and reduces the negative aspects of face to face communication. but the costs are limitation of the exchange of written information. The benefits of video conference is the approximation of face to face communication by providing oral as well as visual communication. but it is insufficient to represent eye contact. The common limitations of ODR are as follows. First is the lack of human face. Second is the neutrality of arbitrators and mediators. Third is the authenticity of electronic document. Fourth is the digital divide across South and North and generations. Fifth is the cross-cultural communication. The development strategy of ODR is the training and education of arbitrators and mediators in the area of writing skill. Furthermore, it is necessary to supplement the weakness of email via diverse kinds of expressions to show emotions. Finally, it is necessary to train neutrals in the area of cross-cultural communication.

• 영어어문교육
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• 제12권2호
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• pp.1-18
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• 2006

This study investigates the types of interactional modifications employed by Japanese and Korean university students during text-based chats. In particular, this study focuses on the role of a network-based medium on the use of interactional modifications, which have been claimed to facilitate interlanguage development. The results show that students use a variety of features of interactional modifications. The most used strategies were the use of paralinguistic features, framing, overt indication of understanding/agreement, and clarification checks, which reveals inconsistent results with findings from research on the negotiation of meaning in face-to-face interaction. Results suggest that the computer-mediated communication (CMC) environment requires the above mentioned strategies and students are able to adapt to this new context by employing alternative strategies. The majority of negotiations were generated by content and lexical items either to resolve communication problems or to better manage interactions, and very few negotiations occurred in terms of grammar. The findings suggest that text-based synchronous chats can be an effective tool for promoting interactive competence, but their effectiveness on grammatical development is uncertain.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 추계학술대회 논문집 학회본부
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• pp.72-76
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• 1997

Interior permanent magnet synchronous motors can be applied to applications requiring wide-speed operation. The current control scheme of an interior permanent magnet synchronous (IPM) motor via feedback linearizing technique is proposed. As the available voltage controlling the armature current is small in transient operations and/or flux-weakening region, the current control performance can be deteriorated. The high performance overmodulation strategy is also proposed to improve the current responses. The control performances are confirmed by simulations.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 전력전자학술대회 논문집
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• pp.305-308
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• 1998

This paper describes a development of interior permanent magnet synchronous motor (IPMSM) and driver for electric vehicle (EV) which is driven by 2 motors without differential gear. A inverter is designed to drive 2 motors with 6 legs IGBT switches in a control board. Also vector control algorithm is implemented with maximum torque control method in the constant torque region and field weakening control method considering inverter capacity in the constant power region. Prototype IPMSM and inverter have been developed. To verify dynamic characteristics of the those about torque to speed and efficiency etc. We are making an experiment on that. Though that is not completed, we will show results to be acquired.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 B
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• pp.779-781
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• 2004

Recently, as the interests in the electrical propulsion ship increase, it is needed to prepare for the technical demand of the versatile HTS synchronous motor, the noble paradigm of the electrical motor. In this paper, the electrical propulsion apparatus was classified at first. The, the merits and demerits of the HTS synchronous motor were investigated. Finally, the feasibility study of development of the HTS motor was performed with electromagnetic FEM analysis. Additionally, the points to be considered in decision of the capacity or number of the HTS motor and the way to supply electricity were studied in this paper. This work would be very useful in establishing the development direction of the HTS motor

• 한국정보과학회논문지:시스템및이론
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• 제26권8호
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• pp.918-929
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• 1999

동기식 스트림 암호통신 방식을 사용하는 암호통신에서는 암/복호화 과정 수행시 암호통신 과정에서 발생하는 사이클슬립으로 인해 키수열의 동기이탈 현상이 발생되고 이로 인해 오복호된 데이타를 얻게된다. 이러한 위험성을 감소하기 위한 방안으로 현재까지 암호문에 동기신호와 세션키를 주기적으로 삽입하여 동기를 이루는 주기적인 동기암호 통신방식을 사용하여 왔다. 본 논문에서는 CDMA(Cellular Division Multiple Access) 이동망에서 데이타서비스를 제공할 때 사용되는 점대점 프로토콜의 주소영역의 특성을 이용하여 단위 측정시간 동안 측정된 주소비트 정보와 플래그 패턴의 수신률을 이용하여 문턱 값보다 작은경우 동기신호와 세션키를 전송하는 비주기적인 동기방식을 사용하므로써 종래의 주기적인 동기방식으로 인한 전송효율성 저하와 주기적인 상이한 세션키 발생 및 다음 주기까지의 동기이탈 상태의 지속으로 인한 오류확산 등의 단점을 해결하였다. 제안된 알고리즘을 링크계층의 점대점 프로토콜(Point to Point Protocol)을 사용하는 CDMA 이동망에서 동기식 스트림 암호 통신방식에 적용시 동기이탈율 10-7의 환경에서 주기가 1sec인 주기적인 동기방식에서 요구되는 6.45x107비트에 비해 3.84x105비트가 소요됨으로써 전송율측면에서의 성능향상과 오복호율과 오복호 데이타 비트측면에서 성능향상을 얻었다. Abstract In the cipher system using the synchronous stream cipher system, encryption / decryption cause the synchronization loss (of key arrangement) by cycle slip, then it makes incorrect decrypted data. To lessen the risk, we have used a periodic synchronous cipher system which achieve synchronization at fixed timesteps by inserting synchronization signal and session key. In this paper, we solved the problem(fault) like the transfer efficiency drops by a periodic synchronous method, the periodic generations of different session key, and the incorrectness increases by continuing synchronization loss in next time step. They are achieved by the transfer of a non-periodic synchronous signal which carries synchronous signal and session key when it is less than the threshold value, analyzing the address field of point-to-point protocol, using the receiving rate of address bits information and flag patterns in the decision duration, in providing data services by CDMA mobile network. When the proposed algorithm is applied to the synchronous stream cipher system using point-to-point protocol, which is used data link level in CDMA mobile network, it has advanced the result in Rerror and Derror and in transmission rate, by the use of 3.84$\times$105bits, not 6.45$\times$107bits required in periodic synchronous method, having lsec time step, in slip rate 10-7.

• 한국콘텐츠학회논문지
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• 제21권8호
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• pp.20-31
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• 2021

COVID-19로 인한 비대면 문화의 확산은 언택트 서비스 혁신과 화상회의 플랫폼을 통한 비대면 커뮤니케이션 확대로 이어졌다. 그러나 실시간 온라인 커뮤니케이션에서는 비언어적 표현을 확인하는 것이 어려워졌고, 특히나 눈 맞춤을 통한 상호작용은 불가능한 상황이다. 감정을 공유하고 친밀감을 쌓는데 도움을 주는 등 눈 맞춤의 긍정적인 효과가 있음에도 불구하고 실시간 온라인 커뮤니케이션에서 눈 맞춤의 효과를 실증적으로 검증한 연구는 전무한 실정이다. 이에 이 연구는 실시간 온라인 커뮤니케이션에서 눈 맞춤의 효과를 검증하고자 하였다. 커뮤니케이션의 맥락과 눈 맞춤 유무에 따라 6가지 영상 처치물을 사용하여 지속 사용 의도, 성과 기대, 상호작용성, 개인적 유대감을 측정하였다. 연구결과, 모든 맥락에서 눈 맞춤이 없을 때보다 눈 맞춤이 있을 때 모든 측정 변인에서 높게 평가되었다. 이 연구는 실시간 온라인 커뮤니케이션에서 눈 맞춤의 효과를 실험을 통해 검증하고 기술의 필요성과 발전 방향을 제안하여 실시간 온라인 커뮤니케이션에서 더 나은 사용자 경험을 제공하는데 기여할 것이다.