• ETRI Journal
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• v.29 no.5
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• pp.688-690
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• 2007

This letter presents a filter for a car navigation system integrating a low-grade inertial measurements unit (IMU) and a global positioning system receiver. The filter is designed according to the state variables to be estimated and the usable measurements. The usable measurements change from case to case, and the estimative state variables also change due to the measurements; therefore, multiple models must be used for real environmental maneuvers. In this letter, four models for land navigation are chosen and switched by rearranging the system matrix and resetting the error covariance matrices.

• Annual Conference on Human and Language Technology
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• 2010.10a
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• pp.152-154
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• 2010

다 영역 대화 시스템 개발에서는 영역 확장이 쉬워야 하며 처리하는 대화 영역이 늘어나더라도 대화 과정에서 사용자 편의성을 유지해야 하는 점이 중요하다. 본 논문에서는 이런 특성을 가지는 다 영역 대화 시스템을 작성하기 위한 프레임워크를 제안한다. 이 프레임워크는 공통의 인터페이스를 구현하는 영역 전문가(Domain Expert) 기반으로 동작하므로 영역 확장이 용이하다. 또한 진행 중이던 대화를 종료하지 않은 채 타 대화 영역으로 이동하는 영역 전환(Domain Switching) 현상은 다 영역 대화를 복잡하게 만드는 주요한 원인 중 하나로써 이를 효과적으로 관리할 수 있는 영역 전환 전략을 사용하여 사용자 편의성을 확보하였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2009.11a
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• pp.679-680
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• 2009

Radio jamming attack is the most effective and easiest Denial-of-Service (DOS) attack in wireless network. In this paper, we proposed a multi-channel MAC protocol to mitigate the jamming attacks by using cognitive radio. The Cognitive Radio (CR) technology supports real-time spectrum sensing and fast channel switching. By using CR technologies, the legitimate nodes can perform periodic spectrum sensing to identify jamming free channels and when the jamming attack is detected, it can switch to un-jammed channel with minimum channel switching delay. In our proposed protocol, these two CR technologies are exploited for thwarting the jamming attacks.

• Proceedings of the IEEK Conference
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• 2000.11a
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• pp.29-32
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• 2000

MPLS stands for “Multi-protocol Label Switching”. It's a layer 3 switching technology aimed at greatly improving the packet forwarding performance of the backbone routers in the Internet or other large networks. We compare the performance of unlabeled IP traffic and labeled IP traffic. In this paper, by varying the packet rate and measuring throughput of the flows we analyze the performance of labeled IP packet traffic and unlabeled IP packet traffic in IP over MPLS.

• Proceedings of the IEEK Conference
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• 2000.11a
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• pp.37-40
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• 2000

Multi Protocol Label Switching (MPLS) is a high performance method for forwarding packets (frames) through a network. It enables routers at the edge of a network to apply simple labels to packets (frames). we use MPLS in the core network for internet. MPLS provide high speed switching and traffic engineering in MPLS domain but at the Label Edge Router(LER) there is frequently cell discarding via congestion and buffer management method. It is one of the most important reasons retransmission and congestion. In this paper we propose advanced LER scheme that provide less cell loss rate also efficient network infrastructure.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1998.11a
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• pp.370-373
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• 1998

현재 인터넷상의 QoS(Quality of Service) 향상을 위해서 여러 가지 방법과 기술들이 소개되고 있다. 이러한 QoS 향상을 위해 트래픽 제어기법과 IS(Integrated Services), DS(Differentiated Services), Tag Switching, MPLS(Multi protocol Label Switching) 등과 같은 방법으로 인터넷에서 보다 나은 서비스를 지원하려는 노력이 시도되고 있다. 본 논문에서는 특히 TCP connection에서의 initial window size의 변경이 네트워크의 QoS, 즉 link의 utilization과 packet의 drop, performance에 어떠한 영향을 주는지를 살펴본다. 그리고, 이에 대한 특성을 분석하고 개선점을 현재의 인터넷에서 가장 많이 사용되어지고 있는 FTP와 web에 대한 모델을 사용하여 가상적으로 시뮬레이션을 해본다.

• Proceedings of the Optical Society of Korea Conference
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• 1995.06a
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• pp.210-215
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• 1995

Technology development toward the use of LiNbO3-based acoustic tunable filters as WDM 2$\times$2 cross-connect switches is reviewed. Recenly, it was found that a fundamental behavior of multi-wavelength Bragg scattering critically affects the crosstalk performance of the acousto-optic tunable filter. We revuew serveral reported methods of overcoming the performance degradation. We will eventually ask whether the device is up to task of WDM optical switching.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2000.10a
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• pp.131-175
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• 2000

• The Transactions of the Korean Institute of Power Electronics
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• v.4 no.4
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• pp.384-394
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• 1999

This paper deals with a fixed frequency full-bridge inverter type DC-DC high-power converter with high frequency high voltage(HFHV) transformer-coupled stage, which operates under quasi-resonant ZVS transition priciple in spite of a wide PWM-based voltage regulation processing and largely-changed load conditions. This multi-resonant(MR) converter topology is composed of a series capacitor-connected parallel resonant tank which makes the most of parasitic circuit reactive components of HFHV transformer and two additional quasi-resonant pole circuits incorporated into the bridge legs. The soft-switching operation and practical efficacy of this new converter circuit using the latest IGBTs are actually ascertained through 50kV trially-produced converter system operating using 20kHz/30kHz high voltage(HV) transformers which is applied for driving the diagnostic HV X-ray tube load in medical equipments. It is proved from a practical point of view that the switching losses of IGBTs and their electrical dynamic stresses relating to EMI noise can be considerably reduced under a high frequency(HF) switching-based phase-shift PWM control process for a load setting requirements.

• Proceedings of the KIEE Conference
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• 2006.10d
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• pp.125-128
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• 2006

This paper presents a novel type soft switching PWM power frequency AC-AC converter using bidirectional active switches or single phase utility frequency AC-high frequency AC matrix converter. This converter can directly convert utility frequency AC (UFAC, 50Hz/60Hz) power to high frequency AC (HFAC) power ranging more than 20kHz up to 100kHz. A novel soft switching PWM prototype of high frequency multi-resonant PWM controlled UFAC-HFAC matrix converter using antiparallel one-chip reverse blocking IGBTs manufactured by IXYS corp. is based on the soft switching resonance with asymmetrical duty cycle PWM strategy. This single phase UFAC-HFAC matrix converter has some remarkable features as electrolytic capacitor DC busline linkless topology, unity power factor correction and sine-wave line current shaping, simple configuration with minimum circuit components, high efficiency and downsizing. This series load resonant UFAC-HFAC matrix converter, incorporating bidirectional active power switches is developed and implemented for high efficiency consumer induction heated food cooking appliances in home uses and business-uses. Its operating performances as soft switching operating ranges and high frequency effective power regulation characteristics are illustrated and discussed on the basis of simulation and experimental results.