• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.10
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• pp.59-66
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• 2003

We propose the novel optical burst switching scheme to guarantee a minimum bandwidth for multiple classes. To date, QoS studies on OBS network are capable of differentiating two classes, but have difficulties in providing a minimum bandwidth lot several classes because of lower classes' collision with the highest class bursts in the networks. To solve that problem, in our proposed scheme we assign time zones in a data channel for each class periodically, making one burst have top priority at least its zone. Also, the new burst assembling algorithm, as well as the way of managing data channel, is necessarily proposed to coordinate with the proposed OBS scheme. Through the evaluation, we show that the worst-case end-to-end delay is small enough and the received bandwidth of the lower classes is still assured regardless of the traffic load of the highest class.

• Journal of Internet Computing and Services
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• v.6 no.3
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• pp.121-128
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• 2005

Recently, as the research of effective resource management for supporting of various next generation internet service, the admission control mechanisms using the dynamic provisioning methods in differentiated service networks are studied. However, even though admission control mechanism is applied to the network, there exits the unfairness of call blocking probability among the different bandwidth requested services. In this paper, we propose the new admission control policy heuristic algorithm that provides fairness of call blocking probability between the large bandwidth requested service and the small bandwidth requested service. The simulation results show that the proposed algorithm provides not only blocking probability fairness but also high bandwidth utilization.

• Journal of Korea Multimedia Society
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• v.14 no.1
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• pp.94-102
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• 2011

To alleviate the size and bandwidth requirement in JPEG2000 system, a new Embedded Compression(EC) algorithm with minor image quality drop is proposed. For both random accessibility and low latency, very simple and efficient hadamard transform based compression algorithm is devised. We reduced LL intermediate memory and code-block memory to about half size and achieved significant memory bandwidth reductions(about 52~73%) through proposed multi-mode algorithms, without requiring any modification in JPEG2000 standard algorithm.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.6A
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• pp.677-682
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• 2004

In this paper, A novel spatial power combiner with wideband printed dipole antennas and balanced amplifier is proposed. The wideband spatial power combiner is proposed to improve power capability and bandwidth by using balanced amplifier and wideband printed dipole antenna, respectively, The proposed 4${\times}$1 spatial power combiner with those components has the characteristics that the 3-dB bandwidth is 1.02 GHz (17 ％), and the effective isotropic power gain (EIPG) is 24.04 dB at 6 GHz. Also, power combining efficiency is 68.69％.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.8
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• pp.45-53
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• 2004

This paper proposes and analyzes a new media access control (MAC) scheduling algorithm, “Interleaved Polling with Deficit Round Robin (IPDRR)” that supports weighted fairness among ONUs in Ethernet Passive Optical Network (PON). The purpose of the proposed IPDRR algerian is not only to eliminate the unused bandwidth of upstream ONU traffic, but also to provide weighted fair sharing of upstream bandwidth among ONUs in Ethernet PON systems. Simulation results show that the IPDRR improves the utilization of upstream channel by removing the unused bandwidth and provides weighted fairness among ONUs, although the IPACT scheduling is unfair according to traffic characteristics.

• The Bulletin of The Korean Astronomical Society
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• v.38 no.1
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• pp.70.2-70.2
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• 2013

한국천문연구원은 일본국립천문대와 한일공동으로 개발한 한일공동VLBI상관기(KJJVC)의 VLBI 관측자들에게 연구결과를 제공할 수 있는 정상운영을 2013년부터 수행하였다. 한일상관센터(KJCC)에서는 평균 8시간정도 관측한 VLBI 관측자료의 상관처리에 소요되는 시간은 약 2주 정도이며, 데이터 분석가의 확인을 거친 후 담당 PI에게 상관결과를 전달하고 있다. 현재 상관처리는 다양한 관측모드 중에서 연구관측에서 많은 비중으로 차지하고 있는 C5(16MHz 대역폭에 16stream) 모드를 지원하고 있으며, 2013년도에 여러 연구자들의 요구에 대응하기 위해 Wideband(512MHz 대역폭), C1(256MHz 대역폭, 1stream), C2(128MHz 대역폭, 2stream) 모드를 지원할 수 있도록 시스템의 성능을 개선할 예정이다. 또한 일본국립천문대에서는 자기테이프를 사용하고 있는 VERA 관측망에 대해 관측자료의 복사시간 단축, 운영효율을 향상시키기 위해 하드디스크를 채용한 OCTADISK 시스템을 개발하였으며, 한일상관센터에도 동기재생처리장치에 장착된 2대의 OCTADDB를 OCTADISK로 수정작업을 추진하였다. 본 보고에서는 이상에 기술한 것과 같이 한일상관센터의 운영현황과 향후 계획에 대해 자세히 기술한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.5
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• pp.939-948
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• 1997

In this paper, we propose the new rate-based transmission rates control algorithm that allocates the fair band-width for ABR service in ATM network. In the traditional ABR service, bandwidth is allocated with constant rate increment or decrement, but in the proposed algorithm, it is allocated fairly to the connected calls by the fuzzy inference of the available bandwidth. The fuzzy inference uses buffer state and the buffer variant rate as the input variables, and uses the total transmission rate as a output variable. This inference a bandwidth is fairly distributed over all ABR calls in service. By simmulation, we showed that the proposed method improved 0.17% in link effectiveness when RIF, RDF is 1/4, 38.6% when RIF, RDF 1/16, and 82.4% when RIF, RDF 1/32 than that of the traditional EFPCA.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.11 no.4
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• pp.401-407
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• 2018

The transmission bandwidth of shorted-monopole antenna in the frequency range of LF and MF was analyzed and the transmission mode considering the permissible data rate dependant on the transmission bandwidth was analyzed in this paper. Based on the required ERP, the output power of transmitter was deduced by considering the antenna efficiency. The analyses are for DGPS and time information transmission system in the frequency range of 283.5kHz and 65kHz respectively. The transmission antenna was modeled as TLM antenna that designed in the limited antenna site. The antenna equivalent circuit and antenna bandwidth were deduced based on the simulation analysis of antenna characteristics. The analyzed antenna bandwidth was compared with the simulated antenna bandwidth. Also the transmission mode for transmitter of LF and MF was proposed by considering the antenna bandwidth.

• Journal of Korea Multimedia Society
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• v.13 no.3
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• pp.349-358
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• 2010

Adaptability is an important issue in video streaming over mobile environments, since the clients may request videos with great differences in their workload. In this paper, we propose the issues in limited bandwidth scheduling for efficient MPEG-4 video stream transmission over a mobile or wireless network. In the phase of admission control, the amount of bandwidth allocated to serve a video request is the mean bandwidth requirement of its requested video. The dynamic allocation of bandwidth in the phase of scheduling depends on the playback buffer levels of the clients with an objective to make it more adaptive to the playback situation of individual clients. In the proposed RTA scheduling protocol, more bandwidth may be allocated temporarily to the client whose buffer level is low. By employing the buffer level based scheduling policy, this protocol attempts to maximize the real-time performance of individual playback while minimizing the impact of transient overloading. Extensive simulation experiments have been performed to investigate the performance characteristics of the RTA protocol as comparing with BSBA protocol. This RTA protocol shows the better performance by transferring more frames than BSBA protocol.Computer simulations reveals that the standard deviation of the bit rate error of the proposed scheme is 50% less than that of the conventional method.

• Journal of the Korea Society of Computer and Information
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• v.17 no.6
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• pp.93-100
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• 2012

In this paper we have proposed a linear time algorithm for solving the minimum sharable-bandwidth tree construction problem. The public-shared network is a user generated infrastructure on which a user can access the Internet and transfer data from any place via access points with sharable bandwidth. Recently, the idea of constructing the SVC video streaming delivery system on public-shared network has been proposed. To send video stream from the stream server to clients on public-shared network, a tree structure is constructed. The problem of constructing a tree structure to serve the video streaming requests by using minimum amount of sharable bandwidth has been shown to be NP-hard. The previously published algorithms for solving this problem are either unable to find solutions frequently or less efficient. The experimental results showed that our algorithm is excellent both in the success rate of finding solutions and in the quality of solutions.