• 한국광학회:학술대회논문집
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• 한국광학회 2001년도 제12회 정기총회 및 01년도 동계학술발표회
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• pp.226-227
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• 2001

CsLiB$_{6}$O$_{10}$(CLBO) 단결정은 넓은 광투과 영역, 극자외선 영역에서의 광투과성, 비교적 큰 비선형 광학계수, 높은 레이저 광손상 문턱값 등의 우수한 특성으로 인해 극자외선 영역에서의 파장변환과 고출력 레이저의 파장변환에 매우 활발한 응용이 시도되고 있다. 본 연구에서는 CLBO 단결정을 이용하여 Nd：YAG 레이저의 1064 nm 파장을 4차 조화파인 266 nm 파장으로 변환시키고 광변환 특성을 조사하였다. (중략)

• 대한전기학회논문지:전력기술부문A
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• 제50권9호
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• pp.424-430
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• 2001

A multi-level optimal power flow(OPF) algorithm has been evolved from a simple two stage optimal Power flow algorithm for constrained power economic dispatch control. In the proposed algorithm, we consider various constraints such as ower balance, generation capacity, transmission line capacity, transmission losses, security equality, and security inequality constraints. The proposed algorithm consists of four stages. At the first stage, we solve the aggregated problem that is the crude classical economic dispatch problem without considering transmission losses. An initial solution is obtained by the aggregation concept in which the solution satisfies the power balance equations and generation capacity constraints. Then, after load flow analysis, the transmission losses of an initial generation setting are matched by the slack bus generator that produces power with the cheapest cost. At the second stage we consider transmission losses. Formulation of the second stage becomes classical economic dispatch problem involving the transmission losses, which are distributed to all generators. Once a feasible solution is obtained from the second stage, transmission capacity and other violations are checked and corrected locally and quickly at the third stage. The fourth stage fine tunes the solution of the third stage to reach a real minimum. The proposed approach speeds up the two stage optimization method to an average gain of 2.99 for IEEE 30, 57, and 118 bus systems and EPRI Scenario systems A through D testings.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 C
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• pp.926-928
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• 1998

A fast optimization algorithm has been evolved from a simple two stage optimal power flow(OPF) algorithm for constrained power economic dispatch. In the proposed algorithm, we consider various constraints such as power balance, generation capacity, transmission line capacity, transmission losses, security equality, and security inequality constraints. The proposed algorithm consists of four stages. At the first stage, we solve the aggregated problem that is the crude classical economic dispatch problem without considering transmission losses. An initial solution is obtained by the aggregation concept in which the solution satisfies the power balance equations and generation capacity constraints. Then, after load flow analysis, the transmission losses of an initial generation setting are matched by the slack bus generator that produces power with the cheapest cost. At the second stage we consider transmission losses. Formulation of the second stage becomes classical economic dispatch problem involving the transmission losses, which are distributed to all generators. Once a feasible solution is obtained from the second stage, transmission capacity and other violations are checked and corrected locally and quickly at the third stage. The fourth stage fine tunes the solution of the third stage to reach a real minimum. The proposed approach speeds up the coupled LP based OPF method to an average gain of 53.13 for IEEE 30, 57, and 118 bus systems and EPRI Scenario systems A through D testings.

• 조명전기설비학회논문지
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• 제29권9호
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• pp.33-41
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• 2015

To improve the power quality of distributed generation (DG) systems even in the presence of distorted grid condition, dual current control scheme of a grid-connected inverter is proposed. The proposed current control scheme is achieved by decomposing the inverter state equations into the fundamental and harmonic components. The derived models are employed to design dual current controllers. The conventional PI decoupling current controller is used in the fundamental model to control the main power flow in DG systems. At the same time, the predictive control is applied in the harmonic model to suppress undesired harmonic currents to zero quickly. To decompose the voltage inputs and state variables into the fundamental and harmonic components, the fourth order band pass filter (BPF) is designed in the discrete-time domain for a digital implementation. For experimental verification, 2kVA prototype of a grid-connected inverter has been constructed using digital signal processor (DSP) TMS320F28335. The effectiveness of the proposed strategy is demonstrated through comparative simulation and experimental results.

• 한국의상디자인학회지
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• 제19권2호
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• pp.145-157
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• 2017

This study aimed to investigate the relationship between values orientation and fashion image orientation with a focus on the new senior generation. The study conducted data analysis by using the SPSS 17.0 program for the final 397 copies excluding incomplete questionnaires. The results of this study are as follows. First, values orientation was drawn as the four factors of social orientation, dependent orientation, family-like orientation, and individual orientation. The fashion image orientation was compartmentalized as three factors: urban image, individual image, and feminine image. Second, social orientation had a significant effect on feminine image as shown in Photo 1, while only individual orientation exerted a significant influence on individual image (Photo 2). Social orientation and family-like orientation respectively exercised a significant influence on individual image and feminine image, and feminine image (Photo 3). Third, the four groups did not show a significant difference in the relationship with the sub-elements of fashion image orientation. It appeared that all four groups were felt as a complex image in which modern, feminine, and individual images were mixed. Fourth, the four groups showed a significant difference in the unusual, elegant, refined, youthful, feminine, and modern images among the factors of fashion image orientation.

• Journal of Communications and Networks
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• 제4권4호
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• pp.336-343
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• 2002

A major challenge for next generation mobile communication is capturing the system architecture’s complexity with all its internal and external dependencies. Seamless integration of heterogeneous environments in all system parts is a key requirement. Moreover, future systems have to consider the different evolution cycles of individual system parts. Among those, services are expected to change the fastest. With respect to these considerations, we propose an overall architecture for next generation mobile communication systems. It covers all system parts from wireless transmission to applications including network and middleware platform. Our approach focuses on adaptability in terms of recon- figurability and programmability to support unanticipated system evolution. Therefore, we consider abstraction layers which consist of adaptable cooperating components grouped by open platforms rather than rigid system layers. In addition to that, we introduce cross-layer cooperation allowing an efficient use of the available resources. Specific scenarios illustrate the feasibility of our approach.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2008년도 International Meeting on Information Display
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• pp.873-878
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• 2008

Doosan Mecatec has developed alignment system for Organic Light-Emitting Diode (OLED) display production using large size substrate. In the present article, The alignment system between the substrate and the mask, which is a core technology for producing the OLED product using the fourth-generation substrate with $730{\times}920mm^2$ or more, will be described by dividing into a substrate loader, a magnet unit, a CCD camera, etc. The substrate loader is optimized through the simulation where the central portion of the substrate droops by about 1.5mm by clamping each of a long side (920mm direction) and a short side (730mm direction) thereof by 6 point and 4 point. A magnet unit using a sheet type of rubber magnet is constituted and a CCD camera model with the specifications capable of minimizing the errors between a clear image and the same image is selected. The system to which an upward evaporation technique of small molecular organic materials will be applied has been developed so that repeatability and position accuracy becomes ${\pm}1{\mu}m$ or less using an UVW type of stage. Also, the vision accuracy of the CCD camera becomes ${\pm}1{\mu}m$ or less and the align process TACT becomes 30sec. or less so that the final alignment accuracy between the substrate and the mask becomes ${\pm}3{\mu}m$ or less. In order to meet an extra-large glass substrate, an evaporation system using an extra-large AMOLED substrate has been developing through a vertical type of an alignment system.

• 한국수학교육학회지시리즈C:초등수학교육
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• 제24권1호
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• pp.43-69
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• 2021

본 연구의 목적은 구성주의를 기반으로 한 학습자 중심수학 수업이 학생들의 학업성취도(실험처치 중 학습한 내용에 대한 재생능력과 실험처치 중 학습하지 않은 내용에 대한 생성능력) 및 추론 능력에 미치는 영향을 알아보는데 있다. 이와 같은 연구 목적을 달성하기 위해서 4학년 분수단원과 다각형 단원을 학습자 중심 수학 수업에 적합한 수업자료와 교수학습 방법을 적용하였다. 본 연구로부터 얻은 결론은 다음과 같다. 첫째, 학습자 중심 수학 수업은 학생들의 학업성취도에 긍정적인 영향을 준다. 둘째, 특히 학습자 중심 수학 수업은 학습 능력이 낮은 학생들에게 긍정적인 영향을 미친다. 셋째, 학습자 중심 수업을 거듭 할수록 학생들의 추론 능력 함양에 긍정적인 영향을 준다. 넷째, 학생들의 추론능력의 함양과 학업성취도의 향상은 서로 긍정적인 영향을 미친다.

• 한국통신학회논문지
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• 제36권12B호
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• pp.1623-1635
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• 2011

4세대 이동통신시스템에서는 사용자가 이용하는 서비스 종류 및 가입한 요금제, 서비스 이용 형태 등에 따라서 각 사용자에게 서로 다른 품질의 서비스를 제공하는 것이 매우 중요하다. 본 논문에서는 단말이 상향링크 자원 요청을 위해서 수행하는 random access 과정을 개선하여 각 사용자 별 서비스 품질 차별화를 도모하였다. 구체적으로 bandwidth request 채널의 구조를 primary 영역과 secondary 영역으로 구분하였고 각 영역을 이용하여 random access를 수행할 수 있는 사용자의 등급을 영역 별로 제한하였다. 이러한 제안 기술을 이용하면 서로 다른 등급의 사용자 사이에 발생하는 불필요한 random access 경쟁을 방지할 수 있기 때문에 전체적인 사용자의 random access 성공 확률을 유지하면서 primary 영역을 이용하여 random access를 시도하는 사용자의 성공 확률을 증가시킬 수 있다. 제안 기술은 2010년 3월 IEEE 802.16 Session #66 회의에서 발표되었고 제안 기술의 개념 및 필요한 메시지가 802. 16m 표준에 채택되는 성과를 거두었다.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2011년도 추계학술대회
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• pp.291-294
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• 2011

4G WiBro 서비스는 우리나라에서 세계표준화한 4세대 통신이다. WiBro 통신 기반에서 응용서비스의 하나인 VoIP가 활성화 되고 있다. WiBro 서비스에서 VoIP를 이용할 때 기존 VoIP 취약점을 보완한 암호화와 인증기술에 대한 연구가 필요하다. 본 논문에서는 4세대 WiBro, LTE를 정의하고, 1G, 2G, 3G와 4G를 비교한다. 그리고 WiBro 서비스에서 VoIP에 대한 기술적, 관리적, 물리적, 해킹 공격 취약점을 분석하고 보안 대책을 연구한다. 보안성 강화를 위한 대책으로 WiBro 서비스에서 VoIP 암호화와 인증을 통한 보안기술에 대하여 연구한다.