• 한국유통학회지:유통연구
• /
• 제13권3호
• /
• pp.27-54
• /
• 2008

본 연구는 가정 내 유통업체(In-home shopping channel)의 다채널 고객관리에 시사점을 제공하기 위하여 가정 내 쇼핑채널로서 TV, 카탈로그 및 인터넷 쇼핑채널 간 소비자의 정보탐색과 구매행동과의 관계를 고찰하였다. 가정 내 쇼핑채널들의 정보탐색과 구매행동과의 관련성을 채널 내 고객 고정(channel lock-in)과 채널 간 시너지(cross-channel synergy)로 구분하여 영향력을 비교 평가하였다. 이를 위하여 1개월 동안의 가정 내 쇼핑채널 이용에 대한 자료를 345명의 가정주부를 대상으로 수집하였다. 소비자의 구매채널 이용행동을 선택, 빈도 및 지출행동으로 구분하여 분석을 수행만 결과 가정 내 쇼핑채널 간 정보탐색과 구매행동 간에는 높은 채널 내 고객 고정 효과가 나타나고 있으며 낮은 채널 간 시너지 효과가 나타나고 있었다. 또한 TV 채널의 경우 카탈로그와 인터넷 채널 간 대체성이 나타나는 반면에 카탈로그와 인터넷 채널은 보완성이 나타나고 있다. 이러만 결과는 가정내 다채널 유통기업에게 채널 간 조정과 통합 및 고객관리에 많은 시사점을 제공하고 있다.

• 한국항행학회논문지
• /
• 제8권2호
• /
• pp.136-144
• /
• 2004

본 논문에서는 Orthogonal frequency division multiplexing(OFDM) 시스템의 성능 향상을 위해 파일럿 심볼을 이용한 향상된 채널추정 알고리즘을 제안한다. 기존의 LMMSE 알고리즘을 이용한 채널추정 방법은 파일럿 심볼만을 채널추정에 이용함으로써 고속의 채널환경하에서 성능이 현저하게 떨어지는 단점이 있다. 이런 문제를 해결하기 위해 파일럿 사이의 채널을 선 추정하고 이 추정된 값을 다시 파일럿과 함께 이용하여 채널을 추정하는 채널추정기법을 제안하였다. 제안된 채널추정 알고리즘은 고속의 채널환경하에서 향상된 성능의 결과를 얻을 수 있었다.

• Journal of Information Processing Systems
• /
• 제13권1호
• /
• pp.141-151
• /
• 2017

Effective identification of wireless channel in different scenarios or regions can solve the problems of multipath interference in process of wireless communication. In this paper, different characteristics of wireless channel are extracted based on the arrival time and received signal strength, such as the number of multipath, time delay and delay spread, to establish the feature vector set of wireless channel which is used to train backpropagation (BP) neural network to identify different wireless channels. Experimental results show that the proposed algorithm can accurately identify different wireless channels, and the accuracy can reach 97.59%.

• Journal of the Optical Society of Korea
• /
• 제17권6호
• /
• pp.494-499
• /
• 2013

In this paper, we present an optical encryption and information authentication of 3D objects considering wireless channel characteristics. Using the optical encryption such as double random phase encryption (DRPE) and 3D integral imaging, a 3D scene with encryption can be transmitted. However, the wireless channel causes the noise and fading effects of the 3D transmitted encryption data. When the 3D encrypted data is transmitted via wireless channel, the information may be lost or distorted because there are a lot of factors such as channel noise, propagation fading, and so on. Thus, using digital modulation and maximum likelihood (ML) detection, the noise and fading effects are mitigated, and the encrypted data is estimated well at the receiver. In addition, using computational volumetric reconstruction of integral imaging and advanced correlation filters, the noise effects may be remedied and 3D information may be authenticated. To prove our method, we carry out an optical experiment for sensing 3D information and simulation for optical encryption with DRPE and authentication with a nonlinear correlation filter. To the best of our knowledge, this is the first report on optical encryption and information authentication of 3D objects considering the wireless channel characteristics.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제5권1호
• /
• pp.68-82
• /
• 2011

Wireless mesh networks (WMNs) provide high-speed backbone networks without any wired cable. Many researchers have tried to increase network throughput by using multi-channel and multi-radio interfaces. A multi-radio multi-channel WMN requires channel assignment algorithm to decide the number of channels needed for each link. Since the channel assignment affects routing and interference directly, it is a critical component for enhancing network performance. However, the optimal channel assignment is known as a NP complete problem. For high performance, most of previous works assign channels in a centralized manner but they are limited in being applied for dynamic network environments. In this paper, we propose a simple flow estimation algorithm and a hybrid channel assignment algorithm. Our flow estimation algorithm obtains aggregated flow rate information between routers by packet sampling, thereby achieving high scalability. Our hybrid channel assignment algorithm initially assigns channels in a centralized manner first, and runs in a distributed manner to adjust channel assignment when notable traffic changes are detected. This approach provides high scalability and high performance compared with existing algorithms, and they are confirmed through extensive performance evaluations.

• 한국정보처리학회:학술대회논문집
• /
• 한국정보처리학회 2009년도 춘계학술발표대회
• /
• pp.842-845
• /
• 2009

Wireless ad hoc networks often suffer from rapidly degrading performance with the number of user increases in the network. One of the major reasons for this rapid degradation of performance is the fact that users are sharing a single channel. Obviously, the problem of using single shared channel schemes is that the probability of collision increases with the number of nodes. Fortunately, it is possible to solve this problem with multi-channel approaches. Due to the especial properties of multiple channels, using the multiple channels is more efficient than single channel because it enhances the capacity of the channel and reduces the error rate during data transmission. Some multi-channel schemes us one dedicated channel for control packets and one separate channel for data transmissions. On the other hand, another protocols use more than two channels for data transmissions. This paper summarizes six multiple channel protocols based on these two kinds of schemes. Then we compare them and discuss the research challenge of multiple channel protocols.

• ETRI Journal
• /
• 제33권5호
• /
• pp.806-809
• /
• 2011

This letter considers the channel estimation for two-way relay MIMO OFDM systems. A least square (LS) channel estimation algorithm under block-based training is proposed. The mean square error (MSE) of the LS channel estimate is computed, and the optimal training sequences with respect to this MSE are derived. Some numerical examples are presented to evaluate the performance of the proposed channel estimation method.

• 동아시아식생활학회지
• /
• 제27권5호
• /
• pp.558-568
• /
• 2017

This study was conducted to examine the level of exposure, credibility and usefulness of the food tourism information channel perceived by foreign tourists visiting Korea. A total of 230 survey questionnaires were distributed to Japanese and Chinese tourists, who account for the highest percentage of tourists visiting Korea. The results showed that tourists were segmented into three groups based on their participation in food tourism activities: culinary tourists, experiential tourists and general tourists. Japanese tourists participated more actively in food tourism activities than Chinese tourists. The information channel used most frequently by tourists was 'word-of-mouth,' while the least used channel was 'e-mail catalog contains food tourism information.' Culinary tourist most actively used online and offline channels to search for food tourism information. Perceived credibility and usefulness of the food tourism information channel differed by nationality and food tourist segments. This study provides meaningful implications regarding food tourism promotion strategies.

• 한국정보통신학회:학술대회논문집
• /
• 한국해양정보통신학회 2008년도 춘계종합학술대회 A
• /
• pp.47-50
• /
• 2008

Multiple-input multiple-output (MIMO) is an efficient technology to increase data rate in wireless networks due to bandwidth and power limitations. Data transmission rate between transmitter and receiver is determined by channel capacity. MIMO has anadvantage of reliable communication over wireless channel because of utilizing the channel capacity properly. In this letter, we drive a new formula, closed form capacity formula, using confluent hypergeometric function.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2004년도 하계종합학술대회 논문집(1)
• /
• pp.293-296
• /
• 2004

This paper proposes an architecture of channel estimation for multi-band OFDM UWB systems presented to IEEE 802.15.3a by Multi-band OFDM alliance(MBOA). The multi-band OFDM (MB-OFDM) systems should have channel estimation for compensation of signal distortion by multi-band channel. The moving-averaging estimation algorithm and multi-band equalization architecture for MB-OFDM UWB systems proposed in this paper was verified by the simulation. Simulation results show that MB-OFDM system with the proposed architecture have the performance improved by about 3.4 dB compared to system with no channel estimation in 0.1$\pi$ phase-rotated channel.