• Journal of the Institute of Convergence Signal Processing
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• v.6 no.2
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• pp.82-88
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• 2005

A compensation scheme for a class of linearly parameterized systems is presented. The compensator consists of a typical linearizing control and an adaptive observer with integration type update law, which is based on Speed Gradient (SG) algorithm.. Instead of the intermediate functions of the compensation schemes suggested by other researchers, the proposed compensator is designed with some design functions which guarantee the growth, convexity, attainability, and pseudo gradient conditions in the update law. The scheme achieves the asymptotic stability of the tracking error and the boundedness of the estimation errors. A numerical example is given to demonstrate the validity of the proposed design.

• The Journal of the Korea institute of electronic communication sciences
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• v.4 no.3
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• pp.224-229
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• 2009

In this paper, an efficient signal interference control technique to improve the convergence speed of Adaptive transversal filter with LMS algorithm is introduced. The convergence characteristics of the proposed algorithm, whose coefficients are multiply adapted in a symbol time period by recycling the received data, are analyzed to prove theoretically the improvement of convergence speed. According as the step-size parameter ${\mu}$ is increased, the rate of convergence of the algorithm is controlled. Increasing the eigenvalue spread has the effect of controlling down the rate of convergence of the adaptive equalizer and also increasing the steady-state value of the average squared error and also demonstrate the superiority of signal interference control to the filter algorithm increasing convergence speed by (B+1) times due to the data-recycling LMS Algorithms.

• The Journal of Korean Association of Computer Education
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• v.9 no.1
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• pp.61-70
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• 2006

In the area of e-learning education, SCORM2004 that is suggested by ADL and is a defacto standard allows to design and apply various interrelations among learning objects which organize learning process through consolidating IMS Simple Sequencing into S&N. In this paper, we intend to realize a web_based adaptive learning management that enable to guide experientially the learning activity through the SCORM 2004 S&N and the Traffic-Signal-Lamp Metaphor. This adaptive system allows professor to design the learning courseware realizing various learning strategies to be able to reuse same learning contents and student to be leaded a adaptive learning through being supplied immediately the state and evaluation of learning.

• The Journal of Korean Association of Computer Education
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• v.4 no.2
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• pp.21-29
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• 2001

The purpose of this study is to design and implementation of the Web-based Individual Computerized Adaptive Testing(CAT) system. The Web-based Individual CAT is a kind of test system to present a set of the problems divided into basic level, intermediate level and advanced level according to the saved results after doing a diagnostic test related to each unit. The diagnostic test is done to pull out the necessary items which learners have to study. The strong points of the web-based computerized adaptive testing system are to reduce the problems of distributed teachers and to have the effect of individual learning by using this system.

• KIISE Transactions on Computing Practices
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• v.21 no.1
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• pp.82-87
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• 2015

There are many current researches that are looking to improve the quality of HTTP adaptive streaming services. However, the existing schemes have a serious problem of QoE (Quality of Experience) degradation because few consider VBR video transmission. To cope with this problem, in this paper, we proposed a novel media quality adaptation scheme called CB-DASH (Content and Buffer-aware DASH). The proposed scheme controlled the video quality considering the VBR characteristics of video and the client's buffer state. Through the simulation, we proved that our scheme accomplished a more accurate estimated bandwidth than the conventional DASH and improved the QoE of streaming service.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.4C
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• pp.343-349
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• 2010

In this paper, we study real time AEC (acoustic echo canceller) based on NLMS adaptive filter. Proposed method improves conversation quality by enhancing the performance of AEC during double talk section and reduces the power consumption by controling the adaption operation of NLMS adaptive filter. Proposed method examines the convergence of the NLMS adaptive filter, stores the estimated echo path and chooses operation of NLMS adaptive filter. Furthermore if double talk is detected, the proposed AEC utilizes the stored echo path optionally considering missed double talk time. When the proposed AEC is used, the performance of the AEC is enhanced although the simple double talk detector is used and the power consumption of the AEC is reduced.

• Proceedings of the KIEE Conference
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• 2000.07d
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• pp.2714-2716
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• 2000

칼라는 물체의 특성을 나타내는 고유한 성질 중의 하나로 칼라 정보를 이용하면 물체를 추적하는데 많은 도움을 얻을 수 있다. 그러나 동일한 칼라의 물체일지라도 조명의 상태나 물체의 형태 등에 따라 실제 이미지 상에 나타나는 칼라는 조금씩 다른 칼라값을 갖는다. 따라서 칼라를 이용하여 물체를 표현하기 위해서는 이미지 상에 나타나는 이러한 물체의 칼라 분포를 효과적으로 모델링할 수 있는 방법이 필요하다. 또한 한번 모델링된 칼라일지라도 물체가 이동하거나 조명이 변화하게 되면 칼라의 분포가 변화하므로 모델링된 칼라가 이러한 변화에도 적절히 대응할 수 있어야 칼라 정보를 이용하여 물체를 추적할 수 있다. 본 논문에서는 이러한 문제를 해결하기 위하여 물체의 칼라 분포를 look-up table을 이용하여 모델링하고 추적하는 물체의 칼라 정보를 이용하여 모델링된 칼라 분포를 다시 갱신하는 적응형 look-up table 방법을 제시하였다. 적응형 look-up table은 모든 칼라값을 테이블로 표현하므로 어떠한 칼라 분포도 모델링할 수 있으며 연산시 단순 참조 방식으로 처리되기 때문에 빠른 계산이 가능하다. 또한 look-up table은 지속적으로 갱신되므로 조명의 변화나 물체의 이동 등으로 인한 칼라 분포의 변화에도 적절히 대응할 수 있다. 본 논문에서는 칼라 정보를 이용하여 물체를 추적하는데 적응형 look-up table을 이용함으로써 적응형 look-up table의 타당성을 검증하였다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.2 no.1
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• pp.71-77
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• 1998

In this Paper, the training principles and the control method of adaptive array antennas using the LMS and CMA algorithms for the $\pi$/4 QPSK signal is showed and the convergence characteristics, the adaptivity of directional pattern SINR and the replication of desired signal of adaptive arrays are compared and discussed each other. Computer simulation results showed that the SINR of LMS adaptive array was 13.8［dB］, and that of CMA was 12.8［dB］, and also the convergence characteristics of LMS was fast a little than that of CMA. The LMS adaptive array was also performed null point well for the interference signal direction than that of the CMA adaptive array.

• Proceedings of the Korea Information Processing Society Conference
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• 2013.05a
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• pp.127-130
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• 2013

분산 응용 시스템의 컴퓨팅 환경이 유비쿼터스 네트워크 환경으로 바뀌면서 기존의 개방성 및 이질성과 같은 특성 외에 적응성이 중요한 이슈로 부각되었다. 적응성을 지원하기 위해 분산 응용 시스템은 컴포넌트를 동적으로 찾아 추가하거나 교체하고 이들 간의 상호작용을 지원해야한다. 최근 이 같은 적응적 상호작용을 위한 역할기반 분산 시스템 모델이 제안되었다. 역할기반 분산 시스템 모델은 응용을 추상적인 역할들로 이루어진 조직으로 보고, 조직을 구성하는 역할과 실제 행위를 수행하는 행위자를 분리한다. 실행 시 응용은 행위자를 역할에 바인딩하고, 행위자는 수행할 역할 업무를 동적으로 응용으로부터 제공받아 실행함으로써 적응성을 높여주는 모델이다. 하지만 이런 역할기반의 분산 시스템 모델을 위한 실행환경의 구축에 대한 연구는 미비한 상태이다. 본 논문에서는 역할기반 분산 시스템 모델의 실행환경으로 응용 프레임워크를 제안한다. 응용 프레임워크는 응용에 필요한 역할들로 이루어진 조직을 구성하고 관리하는 조직 프레임워크와 행위자의 역할 수행과 역할 프로세스 관리를 수행하는 행위자 프레임워크로 나누어진다. 행위자 프레임워크에 대해서는 이전 연구에서 제안하고 있고, 본 논문에서는 이와 결합되는 조직 프레임워크를 구현하기 위해 조직 프레임워크의 요구사항을 분석하고 설계한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.4A
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• pp.421-430
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• 2006

In this paper, we propose a practical implementation of network-adaptive HD(high definition) MPEG-2 video streaming with a cross-layered channel monitoring(CLM) over the IEEE 802.11a WLAN(wireless local area network). For wireless channel monitoring, AP(access point) periodically measures the MAC(medium access control) layer transmission information and sends the monitoring information to a streaming server. This makes that the streaming server reacts more quickly as well as efficiently to the fluctuated wireless channel than that of the end-to-end monitoring(E2EM) scheme for the video adaptation. The streaming sewer dynamically performs the priority-based frame dropping to adjust the video sending rate according to the measured wireless channel condition. For this purpose, our streaming system nicely provides frame-based prioritized packetization by using a real-time stream parsing module. Various evaluation results over an IEEE 802.11a WLAM testbed are provided to verify the intended QoS adaptation capability The experimental results show that the proposed system can effectively mitigate the quality degradation of video streaming caused by the fluctuations of time-varying wireless channel condition.