• 한국위성정보통신학회논문지
• /
• 제6권2호
• /
• pp.35-40
• /
• 2011

본 연구에서는 디지털 라디오 방송을 도입할 경우 기존의 FM 라디오가 새로 배치되는 디지털 라디오 신호의 배치에 의해 받을 수 있는 간섭에 대해 분석을 하였다. 특히 국내에는 FM 라디오 채널에 DARC 방식의 데이터 채널이 포함되어 서비스 되는 라디오 방송이 있어, 디지털 라디오에 의한 FM DARC 채널에의 간섭에 관심이 많은 상황이다. 디지털 라디오 방식은 가장 최근에 개발된 DRM+를 적용하였으며, DRM+ 와 DARC를 포함한 FM 라디오 방송 시스템의 파라메터들을 고려하여 모의실험을 실시하여 분석하였으며, 그 결과 DARC를 포함한 FM 라디오방송이 DRM+에 의해 간섭을 받지 않는 조건은 이격 주파수 150KHz를 기준할 경우 14.7dB임을 알 수 있었다.

• 유통과학연구
• /
• 제20권8호
• /
• pp.9-20
• /
• 2022

Purpose: Distribution competence plays a key role in supply chain management. A successful distribution system will bring high values and profit for company. Omni-channel is a modern type of distribution which is used by many companies to access customers more effectively. This research is about the influence of distribution competence on customer value creation, competitive advantage and business performance of retailers in omni-channel. Research design, data and methodology: Questionnaires were issued to 200 managers who have experiences in using an Omni-channel to provide consumer goods. PLS-SEM is used to check the relationship among these above factors in omni-channel in Vietnam context. Results: Distribution competence has positive direct effect on business performance. At the same time, it has positive indirect effect on business performance through the mediating role of customer value creation and competitive advantage. Moreover, the role of mediating variables make contribution to strengthen the relationship of distribution competence and business performance in omni-channel. Conclusions: Through distribution competence, retailers can get competitive advantage, create more values for customers and increase business performance in omni channel in Vietnam.

• Journal of Communications and Networks
• /
• 제17권1호
• /
• pp.21-26
• /
• 2015

The general wiretap channel with noiseless feedback is first investigated by Ahlswede and Cai, where lower and upper bounds on the secrecy capacity are provided in their work. The upper bound is met with equality only in some special cases. In this paper, we study a special case of the general wiretap channel with noiseless feedback (called non-degraded wiretap channel with noiseless feedback). Inner and outer bounds on the capacity-equivocation region of this special model are provided. The outer bound is achievable if the main channel is more capable than the wiretap channel. The inner bound is constructed especially for the case that the wiretap channel is more capable than the main channel. The results of this paper are further explained via binary and Gaussian examples. Compared with the capacity results for the non-degraded wiretap channel, we find that the security is enhanced by using the noiseless feedback.

• 신재생에너지
• /
• 제3권4호
• /
• pp.8-15
• /
• 2007

Liquid water in flow channel is an important factor that limits the steady and transient performance of PEM fuel cells. A computational fluid dynamics study based on the volume-of-fluid [VOF] multi-phase model was conducted to understand the two-phase flow behavior of liquid water in cathode gas channels. The liquid water transport in $180^{\circ}{\Delta}$ bends was investigated, where the effects of surface characteristics (hydrophilic and hydrophobic surfaces], channel geometries (rectangular and chamfered corners], and air velocity in channel were discussed. The two-phase flow behavior of liquid water with hydrophilic channel surface and that with hydrophobic surface was found very different; liquid water preferentially flows along the corners of flow channel in hydrophilic channels while it flows in rather spherical shape in hydrophobic channels. The results showed that liquid water transport was generally enhanced when hydrophobic channel with rounded corners was used. However, the surface characteristics and channel geometries became less important when air velocity was increased over 10m/s. This study is believed to provide a useful guideline for design optimization of flow patterns or channel configurations of PEM fuel cells.

• 한국통신학회논문지
• /
• 제39A권1호
• /
• pp.65-67
• /
• 2014

본 논문에서는 연속적으로 채널이 변하는 통신망에서 채널 상태 정보의 변화를 추정하여 간섭 정렬을 적용했을 때 간섭 채널의 성능을 분석한다. 채널 상태 정보의 변화를 효과적으로 추정하는 방법을 제안하고, 이를 이용하여 3-user 간섭 채널에 대해 간섭정렬 기법의 성능을 sum rate를 척도로 모의실험을 통해 분석한다. 또한 채널 추정 빈도에 따른 성능을 비교하여 성능과 계산 복잡도 간의 관계를 실험적으로 분석하였다. 실험 결과는 제안된 기법이 프레임 내에서 채널이 변하지 않는다는 가정한 기존의 방식에 비해 성능이 우수함을 확인할 수 있다.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제9권12호
• /
• pp.4967-4986
• /
• 2015

Multi-hop relaying communications have great potentials in improving transmission performance by deploying relay nodes. The benefit is critically dependent on the accuracy of the channel state information (CSI) of all the transmitting links. However, the CSI has to be estimated. In this paper, we investigate the channel estimation problem in one-way multi-hop MIMO amplify-and-forward (AF) relay system, where both the two-hop and three-hop communication link exist. Traditional point-to-point MIMO channel estimation methods will result in error propagation in estimating relay links, and separately tackling the channel estimation issue of each link will lose the gain as part of channel matrices involved in multiple communication links. In order to exploit all the available gains, we develop a novel channel estimation model by structuring different communication links using the PARAFAC and PARATUCK2 tensor analysis. Furthermore, a two-stage fitting algorithm is derived to estimate all the channel matrices involved in the communication process. In particular, essential uniqueness is further discussed. Simulation results demonstrate the advantage and effectiveness of the proposed channel estimator.

• The Korean Journal of Physiology
• /
• 제30권1호
• /
• pp.1-9
• /
• 1996

The objective of the present study was to characterize the role of adenosine in regulation of ATP-sensitive $K^+\;channel\;(K_{ATP}\;channel)$ activity in isolated rabbit ventricular myocytes using the patch clamp technique. Internal adenosine had little effects on KaTr channel activity. In an outside-out patch with intrapipette GTP and ATP, external adenosine stimulated $K_{ATP}\;channel$ activity. In an inside-out Patch with intrapipette adenosine, ATP reduced $K_{ATP}\;channel$ activity, and GTP stimulated $K_{ATP}\;channel$ activity. Adenosine receptor activation shifted the half-maximal inhibition Of $K_{ATP}\;channel\;from\;70\;to\;241\;{\mu}m$. These results Suggest that activation of adenosine receptors stimulates $K_{ATP}\;channels$ in rabbit ventricular myocytes by reducing the apparent affinity of the channel for ATP. The effect may be important for activating $K_{ATP}\;channels$ during early phase of myocardial ischemia.

• 한국멀티미디어학회논문지
• /
• 제13권9호
• /
• pp.1357-1364
• /
• 2010

디지털 방송의 등장으로 다양한 TV 채널들이 시청자에게 제공되고 있지만, 이러한 환경 변화는 오히려 시청자들에게 자신들이 원하는 TV 프로그램을 찾는데 어려움을 겪도록 하고 있다. 이와 같은 어려움을 해소하기 위하여 효율적인 채널 네비게이션 기법(Channel Navigation Scheme)들이 제안되었다. 이 기법들은 시청자의 과거 시청 히스토리 정보를 분석하여 시청자가 선호하는 TV 채널을 예측하고, 시청자가 채널을 변경하고자 할 때 예측된 채널을 제공한다. 기존에 제안된 채널 네비게이션 기법으로는 시청자가 가장 자주 선택한 채널을 제공해 주는 기법인 MFS(Most Frequently Selected)와 가장 최근에 시청한 채널을 제공해주는 기법인 MRS(Most Recently Selected)가 있다. 하지만 MRS, MFS와 같이 시청자의 채널 시청정보에 기반한 방식은 한 채널에서 여러 가지 방송프로그램을 제공하는 현재의 TV 방송에 적합하지 않을 수 있다. 따라서 본 논문에서는 시청자의 채널 시청 정보 대신에 방송프로그램의 시청 정보를 기반으로 채널을 제공해 주는 PMFS(Program Most Frequently Selected)를 제안한다. 또한, 시뮬레이션을 통해 기존의 채널 탐색 기법인 MFS, MRS과 비교하여 PMFS의 탐색 거리(Seek Distance)가 더 짧음을 보인다.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2003년도 학술회의 논문집 정보 및 제어부문 A
• /
• pp.295-298
• /
• 2003

In this paper, a novel maximum a posterion (MAP) estimation for the channel decoding of H.264 codes in the presence of transmission error is presented. Arithmetic codes with a forbidden symbol and trellis search techniques are employed in order to estimate the best transmitted. And, there has been growing interest of communication, the research about transmission of exact data is increasing. Unlike the case of voice transmission, noise has a fatal effect on the image transmission. The reason is that video coding standards have used the variable length coding. So, only one bit error affects the all video data compressed before resynchronization. For reasons of that, channel needs the channel codec, which is robust to channel error. But, usual channel decoder corrects the error only by channel error probability. So, designing source codec and channel codec, Instead of separating them, it is tried to combine them jointly. And many researches used the information of source redundancy In received data. But, these methods do not match to the video coding standards, because video ceding standards use not only one symbol but also many symbols in same data sequence. In this thesis, We try to design combined source-channel codec that is compatible with video coding standards. This MAP decoder is proposed by adding semantic structure and semantic constraint of video coding standards to the method using redundancy of the MAP decoders proposed previously. Then, We get the better performance than usual channel coder's.

• 복식문화연구
• /
• 제24권6호
• /
• pp.803-816
• /
• 2016

The purposes of this study were to investigate the influences of channel assessments on the usage of multi-channels by product types, and the differences in the usage of multi-channels among product types in buying decision making process for fashion products. Data were collected from 510 consumers in their 20s to 50s with purchasing experiences through multi-channel distribution system and living in Seoul and Kyunggi province; 491 were analyzed after deleting incomplete questionnaires. Factor analysis, multiple regression analysis and one-way ANOVA were used for statistical analysis by using SPSS 18.0. The results were as follows: 5 factors were extracted for channel assessment: utility, accuracy, risk, price benefit and sharing information. Price benefits, utility and sharing information for online channel tended to influence positively on the usage of online channel and online+offline channels. Accuracy and low perceived risk of offline influenced positively on offline and on+offline channel usages. The usage levels of on-line and off-line channels for cosmetics were significantly lower than the usage levels for clothes and accessories on information search, evaluation of alternatives, and purchase stages. Significant differences were also found in the usage levels of multi-channels (on+off-line) on information search and evaluation of alternatives stages. The usage levels of the multi-channels for clothes were the highest followed by those of accessories and cosmetics in order.