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UVB radiation changes several photoaging pathway in the body, thereby prompting skin injury. Besides, chronic UVB radiation leads to photoaging, sustained immunosuppression, and photocarcinogenesis. We investigated the protective effect of Timosaponin AIII (TA-III), a naturally occurring steroidal saponin separated from Anemarrhena asphodeloides, against UVB-induced invasive properties of human epidermal keratinocytes (HEKs) and human dermal fibroblasts (HDF). No cytotoxicity was observed up to 50 nM concentration of TA-III. Similarly, TA-III inhibited UVB-induced cyclooxygenase-2 (COX-2), matrix metalloproteinase-9 (MMP-9) transcription level and protein expression in a dose-dependent manner at non-cytotoxic dose. Further, TA-III decreased UVB-induced invasion in primary skin cells. Additionally, TA-III suppressed UVB-stimulates mitogen-activated protein kinase (MAPK) signaling, activator protein-1 (AP-1) and nuclear factor kappa B (NF-κB) activation, thereby preventing the overexpression of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and COX-2 in human epidermal keratinocytes cells. Furthermore, TA-III prevented UVB-mediated formation of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxo-dG) and activation of DNA repair enzymes and, cell cycle arrest genes like as proliferating cell nuclear antigen (PCNA), structural maintenance of chromosomes protein 1 (SMC1). This results support that understanding into the molecular action of TA-III, which can be useful for developing photoprotective agents.

Coix lachryma-jobi L. var. ma-yuen has been a source of food and traditional folk medicine in some parts of Asia for thousands of years; however, the roots of this plant have not been phytochemically investigated. Herein, we report the isolation of a new benzoxazinoid glycoside, coixlachryside B (1), along with ten known compounds (2–11), from the roots of C. lachryma-jobi var. ma-yuen using a variety of chromatographic methods. Among the known compounds, the absolute configuration of compound 4 was determined. The structures of all compounds were elucidated by interpreting NMR spectroscopic data, and experimental and calculated electronic circular dichroism spectra.

Water management plays an important role in obtaining high performance from a polymer electrolyte membrane fuel cell (PEMFC). To reduce the volume and energy consumption of widely-used bubble humidifiers, membrane humidifiers were fabricated by using an ultrafiltration (UF) membrane and Nafion membranes. The performance of the membrane humidifiers was examined as a function of gas flow rate and operating temperature. A single cell was operated using the UF membrane humidifiers exhibiting almost the same performance with that employing bubble humidifiers.

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.

In wireless packet networks, such as IEEE 802.11 Wireless LAN, users can suffer from bad channel quality at cell boundaries, and wireless stations may not overcome the bad communication condition, in spite of using the lowest transmission rate via link adaptation. Unless handoff is considered due to the deployment of APs, the case of initial access to a WLAN network, and so on in such an area, fragmentation can be a unique and compatible solution for coping with the channel limitation. We have evaluated a public WLAN service network, called NESPOT, which is operated by Korea Telecom, especially the case of initial access. We evaluate delay and error performances of NESPOT initial access procedure via both mathematical analysis and simulations. From the results, we conclude that WLAN user can experience enhanced goodput, enlarged reachability, and shortened delay via fragmentation. We also propose a practical method, TCP Maximum Segment Size spoofing to get the same effect as fragmentation. Finally, we propose a policy, called Cut-off delay, for WLAN users not to wait too long time to get an IP address without severe performance degradation.

In Korea, a large-scale IEEE 802.11b-based public wireless LAN (WLAN) service, called NESPOT, has been in operation by Korea Telecom (KT) across the country during the last four years. Along with a fast growth of the service, however, the service quality problems have been encountered. In order to manage and overcome such problems properly, we have developed a diagnostic tool, which is composed of a database for wireless connection-related dissatisfaction, a log collector and analyzer, and a mechanism to report breakdown of access points (APs). To our best knowledge, this is the first attempt to address an integrated management and develop a diagnosis architecture for large-scale commercial WLANs.