• Journal of the Korean Institute of Telematics and Electronics S
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• v.36S no.9
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• pp.1-8
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• 1999

In this paper, we propose and analyze a concatenated coding scheme for DS/CDMA systems in asynchronous channels. In the concatenated coding, bandwidth efficient $2^{2L-2}$-state ${\frac{L}{L+1}}$-rate 2-MTCM with biorthogonal signal constellation is used for the inner code, and $(2^{L-1},\;{\lceil}\frac{2^{L-1}}{L/2}{\rceil})$ RS code is use for the outer code. It is shown that we can get considerable performance gain over the uncoded system without sacrificing the data transmission rate. The proposed system can be used as a coding scheme for reliable and high speed integrated information services of mobile communication systems.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.36S no.10
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• pp.10-20
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• 1999

In this paper, we propose and analyze a multiuser receiver using a decorrelating filter and Viterbi decoders for trellis coded DS/CDMA systems with biorthgonal signal constellation in asynchronous channels. The biorthogonality is implemented by user signature waveforms and the decorrelating filter. The performance of the proposed system is investigated with emphasis on the asymptotic cases. It is shown that the proposed system can provide us with some coding gain and near-far resistance. We also analyze the performance of the proposed system with base-station antenna array.

• The KIPS Transactions:PartA
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• v.13A no.6 s.103
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• pp.525-532
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• 2006

Compared with the previous recovery algorithms for causal message logging, Elnozahy's recovery algerian considerably reduces the number of stable storage accesses and enables live processes to execute their computations continuously while performing its recovery procedure. However, if causal message logging is used with asynchronous checkpointing, the state of the system may be inconsistent after having executed this algorithm in case of concurrent failures. In this paper, we show these inconsistent cases and propose a low-cost recovery algorithm for causal message logging to solve the problem. To ensure the system consistency, this algorithm allows the recovery leader to obtain recovery information from not only the live processes, but also the other recovering processes. Also, the proposed algorithm requires no extra message compared with Elnozahy's one and its additional overhead incurred by message piggybacking is significantly low. To demonstrate this, simulation results show that the first only increases about 1.0%$\sim$2.1% of the recovery information collection time compared with the latter.

• The Journal of the Korea institute of electronic communication sciences
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• v.19 no.1
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• pp.225-232
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• 2024

The Asynchronous indivisual learning offer advantages such as allowing learners to study at their preferred times without spatial constraints. However, since these classes are not conducted in real-time, there are limitations in conveying learners' feedback on problematic or inadequately explained course content to the instructors. This paper proposed a system for relaying feedback information from learners who view course content to the instructors. Learners can investigate the reasons for pausing online recorded class content, and they can transmit these pause reasons along with the time information of the paused content to the instructors. Instructors receive feedback information and pause times of learners' online recorded class videos in graphical form, making it easier to identify areas with numerous issues in the course content at a glance. Instructors can incorporate this feedback to re-upload the content, resulting in higher-quality course materials, which, in turn, can enhance learners' academic achievements.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.12 no.5
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• pp.535-542
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• 1987

In this paper, Modified system of the asynchronous repeat FH/MFSK transmission system is proposed. By transmitting data bits less that address bits, we can improue the system performance, we have evaluated the probability of word error of modified system and compared with the conventional system. And it is found that the modified system shows the improved performance. Also the structure of the receiver is remarkably simplified with the comparison of the conventional system.

• Proceedings of the IEEK Conference
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• 2002.07a
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• pp.149-151
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• 2002

We had been developing the variety of parallel processing systems in order to improve the processing speed of visual media applications. These systems were using multi-access memory system(MAMS) as a parallel memory system, which provides the capability of the simultaneous accesses of image points in a line-segment with an arbitrary degree, which is required in many low-level image processing operations such as edge or line detection in a particular direction, and so on. But, the performance of these systems did not give a faithful speed because of asynchronous feature between MAMS and processing elements. To improve the processing speed of these systems, we have been investigated a pipelined parallel processing system using MAMS. Although the system is considered as being the single instruction multiple data(SIMD) type like the early developed systems, the performance of the system yielded about 2.5 times faster speed.

• Proceedings of the Korea Contents Association Conference
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• 2006.11a
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• pp.37-41
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• 2006

종래의 웹 기반 업무 협업 및 프로젝트 관리 방법으로 제공되는 기술은 ActiveX 나 JVM(Java Virtual Machine)을 이용한 특정 프로그램 설치를 통한 방법으로써 특정 플랫폼이나 브라우저에서만 동작하는 방법을 제공하고 있다. 본 논문에서는 통상적인 웹 기반에서 임의의 프로그램 설치 없이 Ajax(Asynchronous Javascript And XML)를 이용하여 웹 기반 업무 협업시스템을 개발하였다.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.779-784
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• 2001

For electrical vehicles, switched reluctance drives present a promising alternative-compared to asynchronous and synchronous (permanent magnet) concepts. For these applications, a very wide field weakening range is a key issue. Other requirements include high torque output from a small machine and low current ripple at the DC-side without the use of bulky filters - when powered from fuel cells or advanced Lithium-Ion-batteries. A new converter and control strategy according to these requirements is presented and compared to existing designs. The comparison is done for a drive system with a continuous power rating of 30 to 40 kW.

• Electronics and Telecommunications Trends
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• v.13 no.1 s.49
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• pp.41-51
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• 1998

전역 클럭을 사용하는 동기 회로 설계 기술은 설계의 단순화 및 자동화가 용이하기 때문에 현재 많이 사용하는 설계 기술이다. 그러나 다양한 기능과 고성능을 필요로 하는 대규모 시스템이나 회로 설계에서는 전역 클럭 사용으로 인한 신호 지연, 전력 소모 등이 문제로 부각되면서 비동기 회로 설계 기술이 각광을 받고 있다. 비동기 회로 설계 기술은 1940년대에 개발된 기술이지만 설계 자체가 어렵고 면적 증가 등의 단점으로 제한된 분야에서 이용되었다. 현재 이러한 단점을 극복하기 위한 연구가 회로 설계, 검증, 동기/비동기 인터페이스, 그리고 저전력 회로 등의 분야에서 많이 진행되고 있다.

• Electronics and Telecommunications Trends
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• v.14 no.6 s.60
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• pp.1-8
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• 1999

초고속 국가망에 의한 초고속 멀티미디어 정보화 시대가 열릴 때까지 초고속 가입자망으로 각광 받고 있는 Asymmetric Digital Subscriber Line(ADSL) 기술을 전화서비스에 사용되고 있는 기존의 동(copper) 선로를 이용하여 다양한 고속 멀티미디어서비스를 효율적이고 경제적으로 제공할 수 있는 Asynchronous Transfer Mode(ATM) 기반의 ADSL 액세스 시스템에 대하여 논하였다.