• Journal of information and communication convergence engineering
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• 제8권3호
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• pp.273-276
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• 2010

Opportunistic spectrum access (OSA) allows unlicensed users to share licensed spectrum in space and time with no or little interference to primary users, with bring new research challenges in MAC design. We propose a cognitive MAC protocol using statistical channel information and selecting appropriate idle channel for transmission. The protocol based on the CSMA/CA, exploits statistics of spectrum usage for decision making on channel access. Idle channel availability, spectrum hole sufficiency and available channel condition will be included in algorithm statistical information. The model include the control channel and data channel, the transmitter negotiates with receiver on transmission parameters through control channel, statistical decision results (successful rate of transmission) from exchanged transmission parameters of control channel should pass the threshold and decide the data transmission with spectrum hole on data channel. The proposed protocol's simulation will show that proposed protocol does improve the throughput performance via traditional opportunistic spectrum access MAC protocol.

• Journal of information and communication convergence engineering
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• 제8권6호
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• pp.609-617
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• 2010

This paper is concerned with the use of a selforganizing map (SOM) to estimate the desired channel states of an unknown digital communication channel for blind equalization. The modification of SOM is accomplished by using the Bayesian likelihood fitness function and the relation between the desired channel states and channel output states. At the end of each clustering epoch, a set of estimated clusters for an unknown channel is chosen as a set of pre-defined desired channel states, and used to extract the channel output states. Next, all of the possible desired channel states are constructed by considering the combinations of extracted channel output states, and a set of the desired states characterized by the maximal value of the Bayesian fitness is subsequently selected for the next SOM clustering epoch. This modification of SOM makes it possible to search the optimal desired channel states of an unknown channel. In simulations, binary signals are generated at random with Gaussian noise, and both linear and nonlinear channels are evaluated. The performance of the proposed method is compared with those of the "conventional" SOM and an existing hybrid genetic algorithm. Relatively high accuracy and fast search speed have been achieved by using the proposed method.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 동계학술발표대회 논문집
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• pp.215-220
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• 2008

A microchannel PCHE is manufactured by the two technologies of micro photo-etching and diffusion bonding. In this paper, heat transfer and pressure drop characteristics by applying various configuration for the flow channel in the microchannel PCHE is experimentally investigated. The flow channel configurations are designed three types such as straight, wavy and offset strip channels. The performance experiment of each configuration is performed for Reynolds numbers in ranges of $100{\sim}700$ under various flow conditions for the hot side and the Reynolds number of cold side is fixed at 350. The inlet temperatures of the hot side and cold side are conducted as $40^{\circ}C$ and $20^{\circ}C$, respectively. The heat transfer performance of wavy channel, which was similar to that of offset strip channel, was much higher than that of straight channel. The effectiveness of wavy channel and offset strip channel was evaluated as about $0.5{\sim}0.9$. The pressure drop of wavy channel was highest among configurations and that of offset strip channel was lower than that of straight channel because the round curved surface of each strip edge was reduced the pressure loss.

• 통상정보연구
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• 제14권2호
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• pp.81-119
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• 2012

본 연구에서는 유통경로 상의 지배구조 유형이 기업성과에 미치는 영향에 대해 실증적으로 검증해 보았다. 수출유통의 성과를 극대화 하기위한 일반적 전략대안은 수직적 통합에 의한 성과관리이다. 그러나 수출유통에 있어서 소유구조에 의한 수직적 통합은 용이하지 않은 경우가 대부분이다. 본 연구의 결과, 소유구조 이외에도 다양한 관계전략으로 유통성과 관리가 가능하다는 것을 알 수 있었다. 본 연구의 전략적 시사점으로, 수출유통경로결정에 있어서, 소유구조이외에도 거래관계구조 상의 정보교류, 협력관계, 신뢰관계 확립 등을 통하여 유통경로의 수직적 통합과 같은 수준의 성과를 이루어 낼 수 있다는 것을 제시할 수 있다.

• 동의생리병리학회지
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• 제18권5호
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• pp.1275-1284
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• 2004

This paper discuss the acupoints and flowing of channel. The Acupoints issued from the Foot Taiyin channel's energy are seventy three. The acupoints issued from the Foot Shaoyang channel's energy are sixty two. The acupoints issued from the Foot Yangming channel's energy are sixty eight. The acupoints issued from the Hand Taiyang channel's energy are thirty six. The acupoints issued from the Hand Yangming channel's energy are twenty two. The acupoints issued from the Hand Shaoyang channel's energy are thirty two. The acupoints issued from the Du channel's energy are twenty eight. The acupoints issued from the Ren channel's energy are twenty eight. The acupoints issued from the Chong channel's energy are twenty two. The acupoints issued from the Foot Shaoyin channel are the Lianquan points of kidney channel on each side under the tongue. The total points above amount of three hundred and sixty five. Urinary Bladder Channel of Foot-Taiyang: The number of acupoints is 67. Gall Bladder Channel of Foot-Shaoyang: The number of acupoints is 44. Stomach Channel of Foot-Yangming: The number of acupoints is 45.

• 한국통신학회논문지
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• 제30권9A호
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• pp.788-794
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• 2005

In this paper, we focus on the potential of dual polarized antennas in mobile system. thus, this paper designs exact dual polarized channel with Spatial Channel Model (SCM) and investigates the performance for certain environment. Using proposed the channel model; we know estimates of the channel capacity as a function of cross polarization discrimination (XPD) and spatial fading correlation. It is important that the MIMO channel matrix consists of Kronecker product dividable spatial and polarized channel. Through the channel characteristics, we propose an algorithm for the adaptation of transmit antenna configuration to time varying propagation environments. The optimal active transmit antenna subset is determined with equal power allocated to the active transmit antennas, assuming no feedback information on types of the selected antennas. We first consider a heuristic decision strategy in which the optimal active transmit antenna subset and its system capacity are determined such that the transmission data rate is maximized among all possible types. This paper then proposes singular values decision procedure consisting of Kronecker product with spatial and polarize channel. This method of singular value decision, which the first channel environments is determined using singular values of spatial channel part which is made of environment parameters and distance between antennas. level of correlation. Then we will select antenna which have various polarization type. After spatial channel structure is decided, we contact polarization types which have considerable cases It is note that the proposed algorithms and analysis of dual polarized channel using SCM (Spatial Channel Model) optimize channel capacity and reduce the number of transmit antenna selection compare to heuristic method which has considerable 100 cases.

• 한국통신학회논문지
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• 제38B권3호
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• pp.207-215
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• 2013

본 논문은 효율적인 무선 AMI 네트워크를 위한 채널 할당 및 스케줄링 기법에 관한 것이다. AMI 시스템에서, 제안하는 다중채널 클러스터 네트워크는 NC(Network Coordinator)와 CDA(Clustered Data Aggregator) 간의 통신 채널을 네트워크 채널로 정의 하고, CDA와 OMD(Out Meter Display), SMD(Smart Meter Device) 간의 통신채널을 그룹 채널로 정의한다. 네트워크 채널과 그룹채널이 혼합된 다중채널 클러스터 기반의 AMI 네트워크는 물리적/논리적 수용가 채널 클러스터링을 통해서 관리의 효율성을 증대하고, 인접 클러스터간 구별되는 채널 사용을 통한 검침 데이터의 신뢰성을 증대한다. 또한 다중채널 클러스터 기반의 채널할당을 통하여 데이터의 빠른 수집이 가능하며 검침망의 크기를 증가시킨다.

• 한국정보통신학회논문지
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• 제13권7호
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• pp.1422-1428
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• 2009

독립형 무선 인지 시스템은 보통 채널에 대한 면허를 가지는 기사용자가 사용하지 않는 빈 채널을 사용하는 2차 사용자로서 동작한다. 기존연구에서는 이와 같은 2차 사용자가 가용한 채널을 찾을 때, 순차 혹은 무작위로 채널을 선택하여 기사용자의 사용 유무를 확인하였다. 하지만 이러한 방법은 무선 채널의 특성에 맞지 않다. 그러므로 본 논문에서는 이전에 채널을 기사용자가 사용한 경우를 고려하여 가중치 값을 결정하고, 각 채널별 상태 값 중에서 작은 순서대로 채널을 선택함으로써 빈 채널을 찾는데 소요되는 시간을 줄이는 방법을 제안하고, 2차 사용자의 평균 채널 찾기 시간과 평균 전송 횟수의 관점에서 순차적, 무작위적 방법과 그 성능을 비교 분석 한다.

• International Journal of Control, Automation, and Systems
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• 제2권1호
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• pp.23-38
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• 2004

We proposed the infinity control principle to evaluate the Biological function. The H infinity control was applied to the Sodium (Na) ion selective gating channel on the excitable cellular membrane of the neural system. The channel opening, closing and inactivation processes were expressed by movements of three gates and one inactivation blocking particle in the channel pore. The rate constants of the channel state transition were set to be voltage dependent. The temporal changes in amounts per unit membrane area of the channel states were expressed by means of eight differential equations. The biochemical mimetic used to complete the Na ion selective channel was regarded as noise. The control inputs for ejecting the blocking particle with plugging in the channel pore were set for the active transition from inactivated states to a closed or open state. By applying the H infinity control, we computed temporal changes in the channel states, observers, control inputs and the worst case noises. The present paper will be available for evaluating the noise filtering function of the biological signal transmission system.

• 한국유체기계학회 논문집
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• 제13권3호
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• pp.30-36
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• 2010

The detailed heat transfer coefficients on a rotating dimpled channel were measured by the hue detection based the transient liquid crystal technique. The dimples were fabricated on the one side of the channel and the tested channel aspect ratio was 4, 6, and 12 with fixed channel width. Tested Reynolds number based on the channel hydraulic diameter was varied from 21,000 to 47,000. A stationary case and two different rotating conditions were tested so that the dimple fabricated surface became leading or trailing surface. For all rotating conditions, the minimum averaged heat transfer coefficient was measured for the channel aspect ratio of 6. Generally, the highest averaged heat transfer coefficient was observed for the highest aspect ratio cases due to increased dimple induced vortex strength.