• 디지털콘텐츠학회 논문지
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• 제5권2호
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• pp.101-105
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• 2004

The block error probabilities of noncoherent frequency shift keying in a Nakagami fading channel are presented in this papaer. The channel fading speed, show or fast. is consider in evaluating block error probabilities. The effectiveness of diversity combing and error correction coding in improving block error performance is examined. The effect of cochannel interference on block error performance is also studied in this paper.

• 산업공학
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• 제16권3호
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• pp.311-321
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• 2003

We propose the improved channel assignment and management methods for an efficient use of traffic channel resource for supporting 12.2 Kbps, 64 Kbps, and 384 Kbps traffic with the different quality of service(QoS) in the radio network controller(RNC) in asynchronous IMT-2000 system. We consider two types of traffic channel block assignments for utilizing the traffic channel efficiently; the Completely Shared(CS) channel assignment and the Partially Dedicated and Partially Shared(PDPS) channel assignment. The former is that all traffic channel blocks are completely shared with all traffic types. The latter is that some traffic channel block is independently assigned to each traffic type and the other blocks are completely shared with some traffic type. We also propose the traffic channel management method which consists of the block and task management step, for efficiently assigning, releasing, and managing the channel resource. Finally, we evaluate the performance through various numerical examples when applying our proposed channel block assignment and resource management methods.

• 대한기계학회논문집B
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• 제32권10호
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• pp.776-783
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• 2008

The object of this paper is to study on the thermal performance of a micro channel water block for computer CPU cooling. The effects of liquid flow rate, micro channel width and height on the thermal performances of water block are investigated experimentally. The water block was fabricated Al and machined with a micro milling. The water block consisted of rectangular micro channels 0.5 to 0.9 mm width and 1.5 to 4.5 mm height. The experiments were conducted using deionized water, over a liquid flow rate ranging from 0.2 to 2.0 kg/min. The base temperature and thermal resistance decrease with increasing of liquid flow rate. The increase of a channel height is more effective on the thermal resistance than the decrease of a channel width. At the flow rate of 0.7 kg/min, input power of 100 W, the base temperature and thermal resistance of sample 6 is $33^{\circ}C$ and $0.13\;^{\circ}C/W$ respectively.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2008년도 정보통신설비 학술대회
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• pp.12-16
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• 2008

In this paper, we study precoding techniques for co-channel interference suppression in multiuser MIMO systems. DPC is optimal techniques to achieve the system capacity of multiuser MIMO downlink channels. DPC is not proper in practical wireless systems because complexity is very high. So block diagonal precoding for multiuser MIMO downlink channel is studied. The block diagonal precoding is used to suppress co-channel interference between multiuser. Block diagonal precoding method, whose complexity is reduced by modified null space operation, change multiuser MIMO channel to multiple single-user MIMO channel. We also use V-BLAST decoder in receiver. V-BLAST decoder can achieve increased system capacity in proportion to the number of users. We show improved system performance by using computer simulation.

• 설비공학논문집
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• 제8권4호
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• pp.561-575
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• 1996

The interaction of turbulent mixed convection and surface radiation in a three-dimensional channel with the heated blocks is analyzed numerically. Two blocks are maintained at high temperature and the other bottom and horizontal walls are insulated. S-4 method is employed to calculate the effect of the radiative heat transfer. The low Reynolds number k-$\varepsilon$ model proposed by Launder and Sharma is used to estimate the turbulent influence on the heat transfer enhancement. From above modeling, the effects of various channel specifications on the flow and heat transfer characteristics are investigated. The variables used for the present study are Reynolds number, block spacing, the channel height spacing for block and the emissivity. Average Nusselt numbers along the block surfaces are correlated and presented in terms of Reynolds number, emissivity and dimensionless geometric parameters. For the range of conditions in this study, average Nusselt numbers along the block surfaces are strongly influenced by the Reynolds numbers and channel height spacing for block but weakly influenced by the block spacing and the emissivity of the adiabatic walls.

• 한국통신학회논문지
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• 제29권6A호
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• pp.640-650
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• 2004

본 논문에서는 Multiple Put-Multiple output Orthogonal Frequency Division Multiplexing(MIMO-OFDM) 시스템을 위한 채널 추정 기법으로 space-time block c첨ing(STBC) 기법과 space-frequency block coding(SFBC) 기법을 제안한다. 제안된 방식은 각 송신 안테나에서 서로 직교성을 갖는 훈련 심볼을 전송함으로써 수신 안테나에서는 각 송수신 안테나 사인의 채널 계수를 추정한다. 제안된 알고리즘은 IEEE 802.11a 시스템 기반의 MIMO-OFDM 시스템에 적용해 성능 개선 효과를 확인해 보았다. 그 결과 제안된 방법이 기존의 방법보다 더 정확한 채별 계수 추정이 가능함을 확인할 수 있었다. 모의실험은 기존의 추정기법과 제안된 추정 기법이 적용된 시스템을 50ns 와 150ns 의 RMS 지연 확산을 갖는 다중 경로 페이딩 환경에서 수행되었으며 각 변복조 방식에 따른 비트 오류 성능 개선 정도를 확인해 보았다.

• 설비공학논문집
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• 제7권3호
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• pp.461-472
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• 1995

The interaction of laminar mixed convection and surface radiation in a two-dimensional channel with an array of rectangular blocks is analyzed numerically. Three blocks are maintained at high temperature and the other bottom and top horizontal walls are insulated. Discrete ordinate method(DOM) is introduced to analyze the radiative heat transfer. The effects of the variations of Reynolds number and channel specifications on the heat transfer characteristics are investigated. The average Nusselt numbers along the block surfaces are correlated and presented in terms of Reynolds number and dimensionless geometric parameters such as the block spacing, height and channel spacing. For the conditions considered in this study, average Nusselt numbers along the block surfaces are strongly influenced by the channel spacing and Reynolds number but weakly influenced by the block spacing and block height.

• 한국통신학회논문지
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• 제27권2A호
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• pp.99-108
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• 2002

본 논문에서는 불완전한 채널 정보가 시공간 블록 부호의 M-QAM 심볼에러율의 성능에 미치는 영향을 분석한다. 시공간 블록 부호를 복호하기 위해서는 채널 정보가 반드시 필요하므로 불완전한 채널 정보는 시공간 블록 부호의 성능을 저하시키는 원인이 된다. 본 논문에서는 채널 불일치 오차를 발생시키는 주된 원인을 채널 추정의 부정확성으로 인한 오차와 채널의 변화로 인한 오차로 모델링하고 이를 통해 채널 불일치 오차를 분석한다. 그리고 M-QAM 심볼에러율을 채널 불일치 오차 항이 들어간 채널당 평균 신호대 간섭비의 함수로 유도한다. 실험 결과 신호대 잡음비 20dB에서 허용할 수 있는 채널 추정 오차는 $10^{-3}$이고 채널 변화 정도는 f$_{d}$ T$_{B}$=0.001이다.다.

• 한국음향학회지
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• 제38권2호
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• pp.207-213
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• 2019

본 논문은 수중 주파수 선택적 채널에서 블록 인터리빙 기법을 적용한 길쌈부호기법의 통신성능을 평가하였다. 블록 인터리빙은 디지털 데이터 열을 확산 분산하고 재배치하는 기법으로 주파수 선택적 채널에서 연집오류(burst error)의 집중을 분산시켜 성능을 향상하게 시키는 기법으로 블록 인터리빙 기법이 적용되고 있다. 수조 실험에서 블록 인터리빙이 적용된 길쌈부호의 성능을 평가한 결과 주파수 비 선택적 채널에서 블록 인터리빙을 적용한 길쌈부호의 성능의 차이가 없었다. 하지만 주파수 선택적 채널에서는 블록 인터리빙이 적용된 길쌈부호가 길쌈부호보다 2 dB 이득이 발생하였으며, 이로 인해 수중 음향 통신 성능향상에 기여함을 확인하였다.

• The Korean Journal of Physiology and Pharmacology
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• 제3권3호
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• pp.305-313
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• 1999

To explore whether $Cl^-$ channel blockers interact with the ATP-sensitive $K^+\;(K_{ATP})$ channel, I have examined the effect of two common $Cl^-$ channel blockers on the $K_{ATP}$ channel activity in isolated rat ventricular myocytes using patch clamp techniques. In inside-out patches, 4,4'-diisothio-cyanatostilbene- 2,2'-disulfonic acid (DIDS) and niflumic acid applied to bath solution inhibited the $K_{ATP}$ channel activity in a concentration-dependent manner with $IC_{50}$ of 0.24 and 927 ${\mu}M,$ respectively. The inhibitory action of DIDS was irreversible whereas that of niflumic acid was reversible. Furthermore, DIDS-induced block was not recovered despite exposure to ATP (1 mM). In cell-attached and inside-out patches, DIDS blocked the pinacidil- or 2,4-dinitrophenol (DNP)-induced $K_{ATP}$ channel openings. In contrast, niflumic acid did not block the pinacidil-induced $K_{ATP}$ channel openings in inside-out patches, but inhibited it in cell-attached patches. DIDS and niflumic acid produced additional block in the presence of ATP and did not affect current-voltage relationship and channel kinetics. All these results indicate that DIDS among $Cl^-$ channel blockers specifically blocks the cardiac $K_{ATP}$ channel.