• 대한전자공학회논문지SP
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• 제40권4호
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• pp.237-247
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• 2003

움직임 예측은 화질을 유지하면서 영상을 낮은 비트율로 부호화하는 중요한 기술이다. 일반적인 전역 탐색 방법을 사용하면 많은 계산량이 요구된다. 이전의 많은 고속 움직임 예측 방법들은 탐색점의 수를 줄이는데 초점을 두고 있기 때문에 움직임 백터 예측의 정확도가 낮다. 그러므로 본 논문에서는 주위 볼록간의 시공간적 상관관계를 이용하는 새로운 움직임 예측 방법을 제안한다. 신뢰할 수 있는 예측 움직임 벡터(Reliable Predicted Motion Vector : RPMV)를 정의한 후 전역 탐색 방법과 결과를 비교하여 RPMV의 성능을 검증한다. 검증된 RPMV 의 크기와 방향을 이용하는 새로운 움직임 백터 예측 방법을 제안한다. 실험을 통해 제안된 방법을 현재까지 제안된 방법 중 효율적인 것으로 알려진 Nearest Neighbor 방법과 비교하였을 때 약 l1∼14% 정도 속도 향상이 있었다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권12호
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• pp.5135-5149
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• 2015

Communications among multi-party must be fast, cost effective and secure. Today's computing environments such as internet conference, multi-user games and many more applications involve multi-party. All participants together establish a common session key to enable multi-party and secure exchange of messages. Multi-party password-based authenticated key exchange scheme allows users to communicate securely over an insecure network by using easy-to-remember password. Kwon et al. proposed a practical three-party password-based authenticated key exchange (3-PAKE) scheme to allow two users to establish a session key through a server without pre-sharing a password between users. However, Kwon et al.'s scheme cannot meet the security requirements of key authentication, key confirmation and anonymity. In this paper, we present a novel, simple and efficient multi-party password-based authenticated key exchange (M-PAKE) scheme based on the elliptic curve cryptography for mobile environment. Our proposed scheme only requires two round-messages. Furthermore, the proposed scheme not only satisfies security requirements for PAKE scheme but also achieves efficient computation and communication.

• Journal of Communications and Networks
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• 제2권1호
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• pp.58-68
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• 2000

In this paper we introduce the correlation-aided distributed sample acquisition (CDSA) scheme for fast cell search in IMT-2000 W-CDMA cellular system. The proposed scheme incorporates the state symbol correlation process into the comparison-correction based synchronization process of the original DSA scheme to enable fast acquisition even under very poor channel environment. for its realization, each mobile station (MS) has to store in its memory a set of state sample sequences. which are determined by the long-period scrambling sequences used in the system and the sampling interval of the state samples. CDSA based cell search is carried out in two stages : First, the MS first acquires the slot timing by using the primary synch code (PSC) and then identifies the igniter code which conveys the state samples of the current cell . Secondly. the MS identifies the scrambling code and frame timing by taking the comparison-correction based synchronization approach and, if the identification is not done satisfactorily within preset time. it initiates the state symbol correlation process which correlates the received symbol sequence with the pre-stored state sample sequences for a successful identification. As the state symbol SNR is relatively high. the state symbol correlation process enables reliable synchronization even in very low chip-SNR environment. Simulation results show that the proposed CDSA scheme outperforms the 3GPP 3-step approach, requiring the signal power of about 7 dB less for achieving the same acquisition time performance in low-SNR environments. Furthermore, it turns out very robust in the typical synchronization environment where large frequency offset exists.

• 한국통신학회논문지
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• 제38A권4호
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• pp.337-349
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• 2013

본 논문에서는 i-FP(intelligent Fast PMIPv6)로 명명한 새로운 이동성관리 네트워크 기법을 제안한다. i-FP는 지역 이동성관리 문제를 해결하기 위해 고안했다. 하나의 도메인 내에서 MN(Mobile Node)을 다른 네트워크로 이동이 가능하게 하기 위해 i-FP에서는 PMIPv6(Proxy Mobile IPv6)의 세가지 네트워크 엔티티인 LMA(Local Mobility Anchor), MAG(Mobile Access Gateway), MN의 개념을 확장하여 기능을 추가했다. 세가지 네트워크 엔티티로 i-FP에서는 MN의 핸드오버 지연 시간을 감소시키고 IP 헤더 스와핑 메카니즘을 사용하여 트래픽 오버헤드를 회피하여 네트워크 처리량을 증가 시킨다. i-FP의 성능을 평가하기 위해, 새롭게 제안하는 i-FP와 같은 로컬 이동성 관리 프로토콜인 HMIPv6(Hierarchical Mobile IPv6), PMIPv6까지 이상 총 세가지 기법으로 다양한 기준을 사용하여 네트워크 기법의 성능을 측정 / 평가하였다. 성능평가 결과를 종합해서 i-FP가 트래픽 오버헤드가 없어지고 다른 비교 기법 대비 평균 라우팅 홉수 10.2%, 트래픽 시그널링 비용 58.5%, 핸드오버 지연은 16.3% 감소의 성능향상이 일어남을 보여준다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국내학술편); Seoul National University, Seoul; 20-22 Oct. 1993
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• pp.742-748
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• 1993

The dynamics and control of two complex column configurations (sidestream column with stripper; prcfractionater/sidestream column configuration), which are multivariable interacting and nonlinear, have been studied. A new control scheme developed by Hanand Park(1993) to deal with the nonlinear and multivariable nature of distillation processes has been applied to these complex distillation configurations. The control scheme incorporates a nonlinear wave model into a generic model control framework. An observer based on the nonlinear wave model is used to determine the profile positions of distillation column sections. The control scheme enables tight control of the profile position of each column section that leads to fast stabilization of product compositions.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.1710-1715
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• 2005

Two fuzzy controllers are coordinated to control a cartpole such that the pole is balanced as well as the cart is brought back to the track origin. The coordination is due to the BOXES scheme that is established through the evaluation of the outcomes of the control action by one of the fuzzy controllers. It is found that the control scheme is good at selecting proper fuzzy controller so that the pole is balanced fast while the cart moves back to the track origin steadily.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1992년도 한국자동제어학술회의논문집(국제학술편); KOEX, Seoul; 19-21 Oct. 1992
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• pp.550-554
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• 1992

In this paper the issue of convergence rate is introduced for a learning control scheme we have developed and applied for tracking of unknown linear systems. A sufficient condition under which the output trajectory converges exponentially fast is obtained using the controllability grammian of controllable linear systems. Under the same condition it is also shown that the learning control input converges exponentially with the same rate as the rate of output convergence. A numerical example with computer simulation results is presented to show the feasibility of the scheme.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1995년도 추계학술발표회논문집(1)
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• pp.29-34
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• 1995

The good features of the analytic function expansion nodal (AFEN) method are utilized to develop a practical scheme jot the multigroup diffusion problems, in combination with the polynomial expansion nodal (PEN) method. The thermal group fluxes exhibiting strong gradients are solved by the AFEN method[1-6], while the fast group fluxes that are smoother than the thermal group fuzes are solved by the PEN method[7-9]. The scheme is applied to a MOX-fuel loaded core with good results.

• Journal of Electrical Engineering and information Science
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• 제3권3호
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• pp.300-305
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• 1998

This paper describes new sense amplifier with fast sensing delay time of 0.54ns and 32kb CMOS embedded SRAM with 4.67 ns access time for a 3-V power supply. It was achieved using the sense amplifier with multiple point sensing scheme and highs peed bit-line scheme. The sense amplifier saves 25% of the power dissipation compared with the conventional one while maintaining a very short sensing delay. The SRAM uses 0.5m double-polysilicon and triple-metal CMOS process technology. A die size is 1.78${\times}$mm2.13mm.

• 한국콘텐츠학회논문지
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• 제12권12호
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• pp.14-24
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• 2012

분산 비디오 부호화 기법은 우수한 비트율-왜곡 성능을 달성하기 위해 패리티 비트 제어용으로 피드백 채널을 필요로 하고 있다. 그러나 이 방법은 분산 비디오 부호화기법에서 매우 높은 복호화 지연을 야기한다. 실시간 환경에 구현하고 상용화를 촉진하기 위해서, 많은 연구가 고속 복호화 알고리즘 개발에 집중되어 오고 있다. 실시간 구현의 한 방법으로서 본 논문에서는 복호화기에서 부호화기측으로 움직임 정보와 같은 부호화 통계 특성을 제공할 수 있는 응용 환경에 적합한 새로운 분산 비디오 부호화 기법을 다룬다. 즉, 본 논문에서는 보조 정보 생성시에 얻어지는 움직임 정보를 피드백함으로써 복호화 속도를 개선하기 위한 고속 분산 복호화 방식을 제안한다. 모의실험을 통하여, 제안 방식은 기존의 고속 분산 복호화 방식들 보다 우수함을 보인다.