• 한국컴퓨터정보학회논문지
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• 제21권11호
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• pp.65-71
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• 2016

This paper proposes a novel traffic and resource management scheme based on Service Level Agreement (SLA) which allows to guarantee the quality of experience (QoE) for various high-quality mobile multimedia service users to a certain level. For this purpose, QoE-SLA coupling structure is considered and a novel scheme is suggested to suppress the processing delay of the mobile terminal and to decrease the transfer delay in the transmission network. According to simulation results, our proposed scheme can increase the total throughput and decrease the average delay by adjusting SLA.

• 한국정보통신학회논문지
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• 제18권6호
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• pp.1317-1322
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• 2014

본 논문은 GPS 시각 전송 기법 중 GPS 신호가 전달되면서 발생하는 대류층 지연이 시각오프셋 결정에 미치는 영향 정도를 분석하기 위한 연구이다. GPS 시각 전송은 CGGTTS 국제표준을 따르고 있다. 일반적인 측지용 GPS 수신기의 경우, CGGTTS 형태의 시각 전송 값을 출력하지 않고 RINEX 형태의 값을 출력하는데, ROB에서 RINEX 형태의 값을 CGGTTS 형태로 변환하는 r2cggtts 라는 프로그램을 공급하고 있다. 전 세계 표준 시각을 결정하기 위해 TAI link에 참여하는 시각 실험실들은 모두 이 프로그램을 사용하여 주기적으로 CGGTTS 값을 BIPM에 전송한다. r2cggtts 프로그램의 대류층 지연모델은 Chao mapping function과 NATO 천정지연모델이 구현되어 있다. 현재 대표적 대류층 지연 모델은 Niell mapping function과 Saastamoinen 천정지연모델이 사용되고 있는 바, 이 모델들을 r2cggtts 프로그램에 적용하여 시각 오프셋 결정을 위한 두 모델의 지연 결과 값들의 영향을 비교하고 분석한다.

• 한국통신학회논문지
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• 제23권9A호
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• pp.2249-2257
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• 1998

In this paper, we propose the enhanced priority control algorithm that adaptively controls the cell service ratio according to the relative cell occupancy ratio of buffer. The asynchronous transfer mode (ATM) provides the means to support various multimedia services in broadband networks. To support multimedia services, various data traffics of different priorities should be controlled effectively. And also it needs congestion control functions required in the netowrk to carry out the control operation. To accomplish this in a flexible and effective manner, priority classes for the different services ar ecommonly used. The proposed enhanced priority control mechanism have two service calsses of the delay sensitive class and the loss sensitive class. The simulation results show that te proposed control mechanism improves the QoS, the charateristics of cell loss probability and mean cell delay time, by selecting propeor relativ ecell occupancy ratio of buffer and the average arrival rate.

• Animal cells and systems
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• 제2권1호
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• pp.99-106
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• 1998

In this study, we have examined the role of cAMP in gap junctional communication (GJC) in preimplantation mouse embryos. GJC was monitored by Lucifer Yellow (LY) injected into one blastomere of compacted embryos. The speed of GJC was defined as the time taken for the last blastomere of the embryo to become visibly fluorescent. The median time for 8-cell embrvos (140 sec) was similar to that for 16-cell (135 sec). To determine whether cAMP and cAMP-dependent protein kinase (PKA) are involved in the regulation of GJC, the effects of PKA inhibitor (H8) and cAMP analogues (Rp-cAMP and 8-Br-cAMP) on dye transfer between blastomeres of compacted embryos were examined. Some of the embryos treated with either H8 or Rp-cAMP failed to transfer LY to all blastomeres within 10 min. In contrast, 8-Br-cAMP speeded up fluorescent dye transfer. The median time to fill all blastomeres with LY was 140 sec in untreated controls and 90 sec in siblings treated with 8-Br-cAMP. Inhibition of PKA by H8 or Rp-cAMP induced delay or arrest in embryo development after compaction, but the increase of intracellular cAMP showed no effect. These findings suggest that GJC in preimplantation mouse embryos is regulated by cAMP-PKA pathway and transient interference by PKA inhibitors induces the developmental delay beyond compaction.

• 전기학회논문지
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• 제61권11호
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• pp.1590-1594
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• 2012

Depend on delay latency rule for message transmission defined in IEC 61850 standard, the fastest message has to be transferred within 3us. This paper suggests how to structure the real time message transmit test environment of IEC 61850 and develope how to securing IEC 61850 communication performance based on IEC 61850 by measuring delay latency of message transfer on embeded linux system.

• IEIE Transactions on Smart Processing and Computing
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• 제3권6호
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• pp.410-415
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• 2014

This paper presents a new rectifier with a bootstrapping technique to reduce the effective drop voltage. An all-digital delay locked loop (ADDLL) circuit was also applied to prevent the reverse leakage current. The proposed rectifier uses NMOS diode connected instead of PMOS to reduce the design size and improve the frequency respond. All the sub-circuits of ADDLL were designed with low power consumption to reduce the total power of the rectifier. The rectifier was implemented in CMOS $0.35{\mu}m$ technology. The peak power conversion efficiency was 76 % at an input frequency of 6.78MHz and a power level of 5W.

• 융합신호처리학회논문지
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• 제12권1호
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• pp.44-49
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• 2011

The need of data transmission in oceans and other underwater mediums are increasing day by day, so as the research. The underwater medium is very different from that of air. Propagation of electromagnetic wave in water or underground is very difficult because of the conductivity of the propagation materials. In this case, we usually use acoustic signals as ultrasonic but, they are not easy to transfer long distance with coherent method because of time varying multipaths, Doppler effects and attenuations. So, we use non-coherent methods such as FSK or ASK to communicate between long distances. But, as the propagation speed of acoustic wave is very slow, BW of the channel is narrow. It is very hard to guaranty the enough speed for the transmission of digital image data. In previous studies, we proposed this data communication protocol theoretically. In this paper, an underwater channel is modeled and this protocol is tested in this channel condition. The results show that the protocol is 4-6 times faster than ASK. Some relations and results are shown depending on the data length, channel length, bit rate etc.

• 대한전자공학회논문지TE
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• 제37권3호
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• pp.79-85
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• 2000

한정된 용량의 전송선로에서 데이터를 고속으로 전송하기 위해서는 데이터의 압축이 필요하다. 압축은 데이터의 양을 줄이면서 전송선로를 통한 데이터 전송은 빠르고 비용이 절감되도록 만들어 준다. 본 논문에서는 데이터 압축 소프트웨어나 하드웨어를 이용하여 데이터 통신의 응용에 어떻게 적용하는 과정을 전개하고 자 한다. 본 논문에서는 이 적용 과정에서 문제 시 되는 시스템이 원하는 효율과 시스템의 지연 문제를 해결을 위한 방안을 마련하고자 무손실과 다중이력을 지원하는 LZS압축시스템을 이용하여 실시간 데이터 압축전송 시스템을 구현하여 효율을 분석하고자 한다.

• 제어로봇시스템학회논문지
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• 제15권3호
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• pp.346-352
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• 2009

UTC (Coordinated Universal Time) has been made by the comparison results and the statistical analysis of primary clocks maintained by national standard institutes. Some kinds of technique have been used for international time transfer; since 1980s the study on methods and development of time transfer has conducted with activation of GPS application. And the more accurate and easier method made it use the official time transfer method for the generation of UTC. But recently TWSTFT (Two-Way Satellite Time and Frequency Transfers) as well as GPS time transfer are increasing in number because the TWSTFT is able to improve the accuracy and precision of time comparison owing to the elimination of the ionospheric and tropospheric delay errors thanks to the reciprocal propagation path. In this paper, we introduce the TWSTFT results by a multi-channel modem comparing with GPS P3-code.

• 한국정보과학회논문지:시스템및이론
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• 제26권7호
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• pp.827-838
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• 1999

멀티미디어 통신에서 통신 성능에 관련된 요구 사항들은 QoS 매개 변수들로서 서술된다. QoS매개 변수들에서 중요한 매개 변수 중의 하나가 전송 신뢰성이다. QoS 매개 변수로서의 신뢰성은 오류 감지, 보고 그리고 정정 기법으로 정의된다. 하지만 기존의 오류 제어 기법들은 멀티미디어 데이타의 통합된 관점을 고려하지 않았다. 그래서 우리는 MEC(multimedia-oriented error control)라고 명명된 오류 제어 기법을 제안하였다. 1 본 논문에서는 MEC기법의 성능을 조사 하였다. 성능평가 결과는 MEC기법이 기존의 오류 제어 기법보다도 낮은 전송지연(lower delay)과 호손율(blocking probability) 을 갖는다는 것을 볼 수 있었다. 결국 제안된 MEC기법은 수송 프로토콜에게 유연성과 높은 성능을 갖도록 해준다.Abstract Communication performance requirements are described as QoS parameters in multimedia communication. One of the important QoS parameters is the reliability of the transfer. As a QoS parameter, the reliability defines error detection, report and correction mechanisms. Conventional error control mechanisms, however, do not consider the integrated viewpoint of multimedia data. So we have proposed the MEC(multimedia-oriented error control). 1 In this paper, we have investigated the performance evaluation of the MEC. The results show that the MEC mechanism provides lower transfer delay and blocking probability than those of the conventional error recovery mechanism. Therefore, the proposed MEC mechanism makes the transport protocol have the flexibility and high performance.