Current Status and Trend of Internet and E-Commerce Market in Korea

After the remarkable increase of Internet users and broadband Internet subscribers at the end of the 20th century, the size of Korean Internet and e-commerce market steadily increased but the growth rate has been either stagnant or decreased. Trends of Korean Internet and e-commerce market are summarized in this paper the trends on Internet usage are introduced. Trends of online games, blogs and wireless Internet are introduced. The trends of Korean Internet market may have implications for China and Japan.     

AFFS技术在大尺寸LCD-TV的进展（英文）

最近我们发展了AFFS技术,做出了32″LED背光源的LCD-TV,色域达到了105%,对比度1200：1,在140°所有视角的对比度达到了100以上,我们采用双轴补偿膜大大提高了颜色漂移的特性。这些光学特性结果的取得是与工艺制作、光学材料的优化、新AFFS像素的设计分不开的。     

基于GPU的Viterbi并行解码算法的设计与实现

针对GPU并行计算特征,对Viterbi解码自身做了并行处理探索,并提出使用Zero-Termination卷积码来实现基于GPU的Viterbi解码分块并行处理.设计的实现结果表明:Zero-Termination卷积码的简单而适用于GPU分块并行;误码率降低,特别是在信噪比低的情况下,Zero-Termination卷积码误码率比不损失码率的卷积码要低.同时,还实现了基于GPU的7,9,15三种不同约束长度的Viterbi解码,获得了良好的误码性能曲线及高吞吐率表现.     

Enhancement of a WLAN-Based Internet Service

A wireless LAN (WLAN)-based Internet service, called NESPOT, of Korea Telecom (KT), the biggest telecommunication and Internet service company in Korea, has been operational since early 2002. As the numbers of subscribers and deployed access points (APs) increase, KT has been endeavoring to improve its service quality as well as the network management. In this paper, we introduce a joint effort between Seoul National University (SNU) and KT to achieve it. We have been addressing two major issues as part of the joint project thus far: (1) a unified WLAN management/maintenance tool; and (2) real-time traffic support enhancement. We present our on-going efforts as well as some preliminary results. Some issues, which need further attention for the future NESPOT service enhancement, are also introduced.The work reported in this paper was financed and supported by KT. Any opinions, findings, and conclusions or recommendations expressed in this publication are those of the authors and do not necessarily reflect the views of KT. Youngkyu Choi is an M.S. candidate in the department of electrical engineering at Seoul National University (SNU), Seoul, Korea. He received his B.S. with honors in electrical engineering from SNU in 2002. He has a lot of project experiences related with system software development. His current research interests are the design of MAC layer from distributed system to centralized cellular system, resource management in next-generation (4G) cellular system, and mathematical analysis of system performance. He had served in the Korean Army for 3 years from 1998. Sekyu Park is a research staff at the Multimedia & Wireless Networking Lab. (MWNL), Seoul National University (SNU), Seoul, Korea. Before joining MWNL in September 2003, he was with MMC Technology, Seoul, Korea as a Research Staff for five years. His current research interests are in the area of wireless/mobile networks and embedded OS. Sunghyun Choi is an assistant professor at the School of Electrical Engineering, Seoul National University (SNU), Seoul, Korea. Before joining SNU in September 2002, he was with Philips Research USA, Briarcliff Manor, New York, USA as a Senior Member Research Staff and a project leader for three years. He received his B.S. (summa cum laude) and M.S. degrees in electrical engineering from Korea Advanced Institute of Science and Technology (KAIST) in 1992 and 1994, respectively, and received Ph.D. at the Department of Electrical Engineering and Computer Science, The University of Michigan, Ann Arbor in September, 1999. His current research interests are in the area of wireless/mobile networks with emphasis on the QoS guarantee and adaptation, resource management, wireless LAN and PAN, next-generation mobile networks, data link layer protocols, and connection and mobility management. He authored/coauthored over 45 technical papers and book chapters in the areas of wireless/mobile networks and communications. He is the technical program co-chair for ACM International Workshop on Wireless Mobile Applications and Services on WLAN Hotspots (WMASH’2004). He is currently serving on program committees of a number of leading wireless and networking conferences including IEEE INFOCOM, IEEE GLOBECOM, and IEEE VTC. He is also a guest co-editor for a special issue on “Emerging WLAN Applications and Technologies” of Wiley Wireless Communications and Mobile Computing Journal. He is an active participant and contributor of the IEEE 802.11 WLAN standardization committee. Dr. Choi was a recipient of the Korea Foundation for Advanced Studies Scholarship and the Korean Government Overseas Scholarship during 1997–1999 and 1994–1997, respectively. Go Woon Lee is a researcher at Service Development Laboratory, Korea Telecom (KT), Seoul, Korea. She received her B.S. degrees in computer science and material engineering from Korea Advanced Institute of Science and Technology (KAIST) in 1995. She was with Microsoft Korea R&D Group as a research staff in 1995. She received M.S. degree in information & communication from Kwang-Ju Institute of Science and Technology (K-JIST) in 1998. Her current research interests are in the area of wireless/mobile networks with emphasis on data link layer protocols, remote diagnosis, and wireless service management. Jaehwan Lee is a researcher at Korea Telecom (KT), Seoul, Korea. He received his B.S. and M.S. degrees in electrical engineering from Seoul National University (SNU) in 1998 and 2000, respectively. His master’s research was about estimation theory related to Global Positioning System (GPS) and image processing in robot soccer. His current research interest is to analyze and enhance the performance of wireless/mobile networks (IEEE 802.11, sensor networks and mobile ad-hoc networks) regarding QoS, energy-efficiency and high-throughput considering hand-off and inter-networking with heterogeneous networks. Before joining wireless LAN group in KT, he developed the Web-GIS (Geographical Information System) client-server system from 2000 to 2001. Hanwook Jung, Ph.D joined KT in 1985 and got his Ph.D degree with the company finalcial scholarship of KT from 1991 to 1996 at SUNY at Buffalo. His thesis is about “Wireless signal transmission over Fiber by subcarrier multiplexing” which is current heavily utilized for PCS and cellular repeater line. From 1985 to 1991, he had developed a Videotex service which is now known as Hitel. From 1996 to 1999, he developed 26GHz broadband wireless local loop system and contributed to get the license from the government. Since 1999, he has led a business model and service with wireless LAN. The KT Wi-Fi public service, “NESPOT” has 300,000 subscribers and 10,000 public hotspots. In 2003 he was promoted as an assistant vice president leading NESPOT research team to enhance KT’s broadband with 5,000,000 subscribers. His vision regarding next generation communications service is believed to be true by combining the broadband access and wireless technology including WiFi wireless LAN, UWB, and bluetooth in those areas such as wireless home-networking, device-to-device communications, and ubiqutous networking.This revised version was published online in August 2005 with a corrected cover date.     

平流层通信新思路——谷歌气球计划

平流层通信具有低延迟、信道衰落小、造价低廉、机动灵活等特点,在军事应用和应急通信领域都有重要的战略价值,也曾经引起各国的重视,并成为研究热点。然而平流层通信平台的稳定性对各国研究者而言一直是一个挑战,谷歌公司从鸟群飞行中得到启发,开启了Google Loon项目,其目的是为全球偏远地区2/3人口提供速度较快、价格可承受的互联网接入服务,同时为自然灾害发生地区提供通信服务。文中分析了谷歌气球的技术细节,谷歌气球初次试验的情况,以及谷歌气球面临的挑战。谷歌气球计划为平流层通信提供了又一新思路。     

Gelatinization and Liquefaction of Starch with a Heat Stable α-Amylase

Sweet potato and corn starches were gelatinized and liquefied to dextrose equivalent (DE) 10 in a steam-jacketed kettle or in a twin-screw extrusion cooker in a single step process with a heat stable ex-amylase. The time required to gelatinize and liquefy 20% starch slurries in a kettle at 95°C was 45 to 50 sec. Starch powder (10 kg/hr) and water (2-6 kg/hr) were fed to an extrusion cooker to adjust the moisture contents of the starch from 20 to 55% (wet basis) and gelatinized and liquefied to DE 10 at a barrel temperature of 120°C or above with 2 to 3% (w/w) a-amylase added. The optimum conditions for the operation were to feed starch with water to maintain 50% moisture and 2% heat stable a-amylase at a barrel temperature of 120°C.     

EFFECT OF GROWTH TEMPERATURE AND MEDIA ON INACTIVATION OF LISTERIA MONOCYTOGENES BY CHLORINE

The objective of this study was to determine the effect of growth environment on the susceptibility of Listeria monocytogenes to inactivation by hypochlorite sanitizer. Cells were grown in tryptic soy broth (TSB) at 35, 21, and 6°C and in 1:15 dilution of TSB (low nutrient medium, LNM) at 35°C. Late exponential phase cells were harvested, washed, and exposed to a 1 ppm sodium hypochlorite solution for periods up to 5 min. After 30 s exposure, cells grown at 35°C in TSB were reduced in number by 2.1 ± .3, at 21°C, 3.1 ± .3 and at 6°C, 3.4 ± .3 log units. After 30 s exposure to 5 ppm free chlorine cells grown at 35°C in TSB were reduced in number by 5.2 ± .2 and in LNM by 3.1 ± .1 log units. These data demonstrate that growth environment has a significant effect on chlorine inactivation of L. monocytogenes.     

Characterization of Polyphenoloxidase from Ravat 51 and Niagara Grapes

Polyphenoloxidase (PPO) was isolated from two varieties of grapes grown in the northeastern United States and its characteristics were studied. The temperature and pH optima for both enzymes were 25°C and 5.5, respectively. The thermal inactivation of PPO followed first-order kinetics; with the Niagara enzyme being more heat stable than Ravat PPO. The substrate specificity of the grape PPO clearly showed high affinity toward the o-diphenolic compounds, with a high affinity toward caffeic acid. Inhibition studies indicated that L-cysteine and sodium diethyldithiocarbamate were the most potent.     

A Microscopical Study of the Structure of Meat Emulsions and Its Relationship to Thermal Stability

Meat emulsions were examined by light microscopy to determine the relationships between structure and emulsion stability. Beef-meat based emulsions were prepared either by varying chopping temperature or by adding soy plastic fats of different hardness. Formation of fat channels was observed in uncooked emulsions prepared either at a chopping temperature of 26°C or with soft plastic fat of 0.25cm^?1 hardness index. Such fat channel formations caused discontinuity of protein matrix, leading to fat separation during cooking and weakening of textural strength of products. Changes in fat globule size and distribution as affected by melting properties or hardness of fats were clearly reflected by changes in emulsion stability. Results suggest that emulsion stability is determined largely by the physical properties of protein matrix and fat incorporated. Stable emulsions were obtained with fats of appropriate melting properties and hardness and relatively cohesive protein matrix under given comminution conditions which allowed uniform fat distribution.     

弹性基体磨具的磨抛轨迹与表面加工质量研究

目的 解决以光学玻璃为代表的硬脆材料加工效率与表面质量难以同时得到保证的共性问题。方法 以弹性基体工具磨削抛光技术为基础,分析弹性接触区域内有效工作磨粒的运动行为。基于Preston方程材料去除模型,研究磨抛过程中磨抛接触区域的接触面积、速度分布、多颗磨粒的运动轨迹。基于运动学模型,探究磨抛过程中磨具的运动学参数、磨粒浓度及排布特征等因素对磨粒磨抛轨迹的影响,采用磨具与工件接触区域磨粒运动轨迹相对面积占比和变异系数表征磨粒运动轨迹分布的均匀性,并建立基于轨迹均匀性的加工表面质量评价方法,优化工艺参数。以石英玻璃为加工对象,以硅橡胶中混入金刚石磨粒为基体,通过正交实验研究不同参数对工件表面质量的影响。结果 仿真结果表明,选取自转速度为300 r/min、进给速度为1 mm/s、磨抛进动角为15°,磨粒浓度及排布采用1 mm磨粒理论间距,此时获得的最大磨粒运动轨迹相对面积占比为96.46%,最小变异系数为0.375。通过实验,得到了选取磨抛工艺参数中的最佳参数组合,自转速度为1 200 r/min,进给速度为1 mm/s,磨抛进动角为15°~20°,磨粒浓度及排布采用磨粒间距1 mm,该组合可将工件的表面粗糙度由1.078 μm降至0.057 μm,材料去除率为3.8×10⁸ μm³/min。结论 磨粒运动轨迹的密集程度与自转速度、磨粒浓度及排布呈正相关,与进给速度呈负相关,在考虑加工成本的前提下,采用高自转速度、高磨粒浓度、低进给速度及15°~20°的进动角可以获得密集且均匀的磨粒运动轨迹,提高了工件的表面质量和材料去除效率。