• 대한약학회:학술대회논문집
• /
• 대한약학회 2003년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.2-2
• /
• pp.188.2-188.2
• /
• 2003

Large-conductance $Ca^{2+}$ activated potassium channels $(BK_{ca})$ are widely distributed and play key roles in various cell functions. In nerve cells, B $K_{ca}$ channels shorten the duration of action potentials and block $Ca^{2+}$ entry thereby repolarizing excitable cells after excitation. $(BK_{ca})$ channel opening has been postulated to confer neuroprotection during stroke and has attracted attention as a means for therapeutic intervention in asthma, hypertension, convulsion, and traumatic brain injury. (omitted)

• 한국통신학회논문지
• /
• 제40권11호
• /
• pp.2305-2315
• /
• 2015

무선통신의 발전에 따라 주파수 자원 가치는 더욱 커지고 있다. 또한 정보화 사회 발전에 따라 주파수 자원의 수요가 공급에 비하여 매우 크기 때문에 주파수 부족 현상이 심각한 실정이다. 따라서 사용하지 않는 주파수 자원을 효율적으로 이용하기 위한 기술로서 최근 Cognitive Radio (CR) 기술이 각광 받고 있다. 본 논문에서는 주파수 홉핑 기반 인지무선 애드 혹 네트워크에서 새로운 out-of-band 주파수 센싱 기법과 동적 채널 엑세스 방법에 대해 제안한다. 제안된 방법에서 CR 멤버노드들은 현재 홉핑 시간의 초반부에 다음 홉핑 채널에 대한 센싱을 수행하고, 제안된 주사용자 감지 신호 방송 기법에 따라 각 노드는 현재 채널에 대한 홉핑 시간 연장여부를 결정한다. 주사용자가 발견되어 잠정적으로 사용하지 않았던 채널이 다시 사용가능한 상태가 되면 해당 채널을 원래의 홉핑 패턴에 포함시키는 채널 복구절차를 수행한다. 본 논문에서는 제안된 동적 주파수 센싱과 홉핑 채널 연장 메커니즘에 대해 다양한 무선 환경에서의 성능평가를 수행하였다. 제안된 방식은 기존 방식에 비하여 채널 효율을 높이고 신뢰할 수 있는 채널 관리를 수행할 수 있음을 확인하였다.

• 한국유체기계학회 논문집
• /
• 제17권5호
• /
• pp.60-66
• /
• 2014

Most tidal current turbine designs are focused on medium and large scale for deep sea, less attention is paid in low water level channel, such as the region around the islands and costal sea. This study is to develop a horizontal axis tidal current turbine rotor blade which is applicable to low water level island region in southwest coastal region of Korea. In this study, the hydrofoil NACA63-415 and NACA63-817 are both adopted to analyze. The blade using NACA63-817 showed the higher maximum power coefficient and good performance at small TSR (Tip Speed Ratio), which gives the blade more advantages in operating at lower water level channel, where is characterized by the fast-flowing water. The cavitation pattern of hydrofoil is predicted by the CFD analysis and verified that the NACA63-817 is the appropriate hydrofoil in the test site of tidal current resource and the hydrofoil showed considerable performance in avoiding cavitation.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
• /
• pp.242-242
• /
• 2012

Transparent oxide semiconductors are increasingly becoming one of good candidates for high efficient channel materials of thin film transistors (TFTs) in large-area display industries. Compare to the conventional hydrogenated amorphous silicon channel layers, solution processed ZnO-TFTs can be simply fabricated at low temperature by just using a spin coating method without vacuum deposition, thus providing low manufacturing cost. Furthermore, solution based oxide TFT exhibits excellent transparency and enables to apply flexible devices. For this reason, this process has been attracting much attention as one fabrication method for oxide channel layer in thin-film transistors (TFTs). But, poor electrical characteristic of these solution based oxide materials still remains one of issuable problems due to oxygen vacancy formed by breaking weak chemical bonds during fabrication. These electrical properties are expected due to the generation of a large number of conducting carriers, resulting in huge electron scattering effect. Therefore, we study a novel technique to effectively improve the electron mobility by applying environmental annealing treatments with various gases to the solution based Li-doped ZnO TFTs. This technique was systematically designed to vary a different lithium ratio in order to confirm the electrical tendency of Li-doped ZnO TFTs. The observations of Scanning Electron Microscopy, Atomic Force Microscopy, and X-ray Photoelectron Spectroscopy were performed to investigate structural properties and elemental composition of our samples. In addition, I-V characteristics were carried out by using Keithley 4,200-Semiconductor Characterization System (4,200-SCS) with 4-probe system.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2009년도 하계학술대회 논문집
• /
• pp.44-44
• /
• 2009

Recently, transparent ZnO-based TFTs have attracted much attention for flexible displays because they can be fabricated on plastic substrates at low temperature. We report the fabrication and characteristics of ZnO channel layers(ZnO TFTs) having different channel thicknesses. The ZnO film were deposited as active channel layers on $Si_3N_4/Ti/SiO_2p$-Si substrates by rf magnetron sputtering at $100\;^{\circ}C$ without additional annealing. Also the Zno thin films deposited at oxygen partial pressures of 40%. ZnO TFTs using a bottom-gate configuration were investigated. The $Si_3N_4$ film were deposited as gate insulator by PE-CVD at $15\;^{\circ}C$. All Processes were processed below $150^{\circ}C$ which is optimal temperature for flexible display and were used dry etching method.

• 한국IT서비스학회지
• /
• 제13권4호
• /
• pp.377-396
• /
• 2014

There is a phenomenon that the consumers from all over the countries are using the Korean online shopping malls, which has settled as a distribution industry. To get the attention of the consumers from other countries, the marketing strategy is important in order for the online shopping malls to go advance abroad. The purpose of this study is to overview the Pinterest, which is a shopping-oriented Social Network Service (SNS) based on the image content. The Pinterest is a valuable online shopping mall marketing channel. By looking at the background growth and feature of service, the existence of the mega SNS as a center in the social business is to see how Pinterest is targeting a niche market. As a result of this study, Pinterest has the advantage against other SNS for joining with online shopping malls because a tendency of the traffic referrals from Pinterest is increasing and the average of the cost of the purchase is high. Therefore, this study is reflecting various cases of utilizing the online shopping malls. In conclusion, Pinterest represents an illustrative case of effective marketing channel of the online shopping malls.

• 한국정보통신학회논문지
• /
• 제8권8호
• /
• pp.1613-1619
• /
• 2004

긴 블럭 크기의 터보부호는 AWGN(Additive White Gaussian Noise) 채널 환경에서 매우 좋은 성능을 보이는 것으로 알려져 있으며, 또한 3GPP(3rd Generation Partnership Project)의 W-CDMA(Wideband Code Division Multiple Access)에서는 터보부호를 에러 정정 코드로 강력하게 권장하고 있다. 최근 실시간 통신 시스템을 위해서 짧은 블럭 크기를 갖는 터보부호에 대한 관심이 고조되고 있다. 따라서 본 논문에서는 ITU-R 실측 채널 모델에서 1/3의 부호화율과 192 비트의 짧은 프레임 크기를 갖는 터보부호를 고려하였다. 본 논문에서는 MRC(Maximal Ratio Combining) 다이버시티와 SOVA(Soft Output Viterbi Algorithm)에 기초한 터보부호를 동시에 갖는 RAKE 수신기를 적용한 10MHz 시스템 대역폭을 갖는 W-CDMA 시스템의 성능을 분석하였다.

• Journal of Astronomy and Space Sciences
• /
• 제37권1호
• /
• pp.11-18
• /
• 2020

Satellite optical communication has gained significant attention owing to its many quality features (e.g., a larger bandwidth, license free spectrum, higher data rate, and better security) compared to satellite microwave communication. Various experiments have been performed during many space missions to demonstrate and characterize inter-satellite links, downlinks, and uplinks. Korea has also planned to establish an experimental communication system using a geostationary earth orbit (GEO) satellite and the Geochang station as an optical ground station for low Earth orbit (LEO)-to-ground optical relay links. In this study, the performance of inter-satellite communication links and downlinks was investigated for the new Korean experimental communication system in terms of link margin, bit error rate (BER), and channel capacity. In particular, the performance of the inter-satellite links was analyzed based on the receiving apertures and the transmitting power, while that of the downlink was analyzed in terms of atmospheric turbulence conditions and transmitting power. Finally, we discussed two system parameters of receiving aperture and transmitting power to meet the three criteria of link margin, BER, and channel capacity.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제8권4호
• /
• pp.1324-1343
• /
• 2014

In recent years, the problem of spectrum mobility in Cognitive Radio (CR) Networks has been widely investigated. In order to utilize spectrum resources completely, many spectrum handoff techniques based on game theory have been proposed, but most studies only concern that users how to achieve better payoffs, without much attention to the diverse needs of users. In this paper, we propose a new channel-switching model based on game theory, using a prioritized approach to meet the diverse needs of users in two different modes (CQ and PS). At the same time, this paper proposes some acceleration techniques to reach the Nash equilibrium more efficiently. We evaluate the performance of the proposed schemes depending on priority using real channel availability measurements, and conclude that the channel quality function (CQ) mode provide better service for priority user but the plan-sorting (PS) mode can be more suitable in multiple priority users exist scene.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제11권2호
• /
• pp.611-627
• /
• 2017

For enhancing the coverage of wireless networks and increasing the spectrum efficiency, small cell networks (SCNs) are considered to be one of the most prospective schemes. Most of the existing literature on resource allocation among non-cooperative small cell base stations (SBSs) has widely drawn close attention and there are only a small number of the cooperative ideas in SCNs. Based on the motivation, we further investigate the cooperative approach, which is formulated as a coalition formation game with power control algorithm (CFG-PC). First, we formulate the downlink sub-channel resource allocation problem in an SCN as a coalition formation game. Pareto order and utilitarian order are applied to form coalitions respectively. Second, to achieve more availability and efficiency power assignment, we expand and solve the power control using particle swarm optimization (PSO). Finally, with our proposed algorithm, each SBS can cooperatively work and eventually converge to a stable SBS partition. As far as the transmit rate of per SBS and the system rate are concerned respectively, simulation results indicate that our proposed CFG-PC has a significant advantage, relative to a classical coalition formation algorithm and the non-cooperative case.