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Search Results: 1 - 10 of 36420 matches for " Sang-Gon Lee "
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E-SAP: Efficient-Strong Authentication Protocol for Healthcare Applications Using Wireless Medical Sensor Networks
Pardeep Kumar,Sang-Gon Lee,Hoon-Jae Lee
Sensors , 2012, DOI: 10.3390/s120201625
Abstract: A wireless medical sensor network (WMSN) can sense humans’ physiological signs without sacrificing patient comfort and transmit patient vital signs to health professionals’ hand-held devices. The patient physiological data are highly sensitive and WMSNs are extremely vulnerable to many attacks. Therefore, it must be ensured that patients’ medical signs are not exposed to unauthorized users. Consequently, strong user authentication is the main concern for the success and large scale deployment of WMSNs. In this regard, this paper presents an efficient, strong authentication protocol, named E-SAP, for healthcare application using WMSNs. The proposed E-SAP includes: (1) a two-factor (i.e., password and smartcard) professional authentication; (2) mutual authentication between the professional and the medical sensor; (3) symmetric encryption/decryption for providing message confidentiality; (4) establishment of a secure session key at the end of authentication; and (5) professionals can change their password. Further, the proposed protocol requires three message exchanges between the professional, medical sensor node and gateway node, and achieves efficiency (i.e., low computation and communication cost). Through the formal analysis, security analysis and performance analysis, we demonstrate that E-SAP is more secure against many practical attacks, and allows a tradeoff between the security and the performance cost for healthcare application using WMSNs.
Performance Evaluation of Multi-Channel Wireless Mesh Networks with Embedded Systems
Jun Huy Lam,Sang-Gon Lee,Whye Kit Tan
Sensors , 2012, DOI: 10.3390/s120100500
Abstract: Many commercial wireless mesh network (WMN) products are available in the marketplace with their own proprietary standards, but interoperability among the different vendors is not possible. Open source communities have their own WMN implementation in accordance with the IEEE 802.11s draft standard, Linux open80211s project and FreeBSD WMN implementation. While some studies have focused on the test bed of WMNs based on the open80211s project, none are based on the FreeBSD. In this paper, we built an embedded system using the FreeBSD WMN implementation that utilizes two channels and evaluated its performance. This implementation allows the legacy system to connect to the WMN independent of the type of platform and distributes the load between the two non-overlapping channels. One channel is used for the backhaul connection and the other one is used to connect to the stations to wireless mesh network. By using the power efficient 802.11 technology, this device can also be used as a gateway for the wireless sensor network (WSN).
RUASN: A Robust User Authentication Framework for Wireless Sensor Networks
Pardeep Kumar,Amlan Jyoti Choudhury,Mangal Sain,Sang-Gon Lee,Hoon-Jae Lee
Sensors , 2011, DOI: 10.3390/s110505020
Abstract: In recent years, wireless sensor networks (WSNs) have been considered as a potential solution for real-time monitoring applications and these WSNs have potential practical impact on next generation technology too. However, WSNs could become a threat if suitable security is not considered before the deployment and if there are any loopholes in their security, which might open the door for an attacker and hence, endanger the application. User authentication is one of the most important security services to protect WSN data access from unauthorized users; it should provide both mutual authentication and session key establishment services. This paper proposes a robust user authentication framework for wireless sensor networks, based on a two-factor (password and smart card) concept. This scheme facilitates many services to the users such as user anonymity, mutual authentication, secure session key establishment and it allows users to choose/update their password regularly, whenever needed. Furthermore, we have provided the formal verification using Rubin logic and compare RUASN with many existing schemes. As a result, we found that the proposed scheme possesses many advantages against popular attacks, and achieves better efficiency at low computation cost.
A Security Analysis of the 802.11s Wireless Mesh Network Routing Protocol and Its Secure Routing Protocols
Whye Kit Tan,Sang-Gon Lee,Jun Huy Lam,Seong-Moo Yoo
Sensors , 2013, DOI: 10.3390/s130911553
Abstract: Wireless mesh networks (WMNs) can act as a scalable backbone by connecting separate sensor networks and even by connecting WMNs to a wired network. The Hybrid Wireless Mesh Protocol (HWMP) is the default routing protocol for the 802.11s WMN. The routing protocol is one of the most important parts of the network, and it requires protection, especially in the wireless environment. The existing security protocols, such as the Broadcast Integrity Protocol (BIP), Counter with cipher block chaining message authentication code protocol (CCMP), Secure Hybrid Wireless Mesh Protocol (SHWMP), Identity Based Cryptography HWMP (IBC-HWMP), Elliptic Curve Digital Signature Algorithm HWMP (ECDSA-HWMP), and Watchdog-HWMP aim to protect the HWMP frames. In this paper, we have analyzed the vulnerabilities of the HWMP and developed security requirements to protect these identified vulnerabilities. We applied the security requirements to analyze the existing secure schemes for HWMP. The results of our analysis indicate that none of these protocols is able to satisfy all of the security requirements. We also present a quantitative complexity comparison among the protocols and an example of a security scheme for HWMP to demonstrate how the result of our research can be utilized. Our research results thus provide a tool for designing secure schemes for the HWMP.
The impact of dose of the angiotensin-receptor blocker valsartan on the post-myocardial infarction ventricular remodeling: study protocol for a randomized controlled trial
Young-Rak Cho, Young-Dae Kim, Tae-Ho Park, Kyungil Park, Jong-Sung Park, Heekyung Baek, Sun-Young Choi, Kee-Sik Kim, Taek-Jong Hong, Tae-Hyun Yang, Jin-Yong Hwang, Jong-Seon Park, Seung-Ho Hur, Sang-Gon Lee
Trials , 2011, DOI: 10.1186/1745-6215-12-247
Abstract: Valsartan in post-MI remodeling (VALID) is a randomized, open-label, single-blinded multicenter study designed to compare the efficacy of different clinical dose of valsartan on the post-MI ventricular remodeling. This study also aims to assess neurohormone change and clinical parameters of patients during the post-infarct period. A total of 1116 patients with left ventricular dysfunction following the first episode of acute ST-elevation MI are to be enrolled and randomized to a maximal tolerable dose (up to 320 mg/day) or usual dose (80 mg/day) of valsartan for 12 months in 2:1 ratio. Echocardiographic analysis for quantifying post-MI ventricular remodeling is to be conducted in central core laboratory. Clinical assessment and laboratory test are performed at fixed times.VALID is a multicenter collaborative study to evaluate the impact of dose of valsartan on the post-MI ventricular remodeling. The results of the study provide information about optimal dosing of the drug in the management of patients after MI. The results will be available by 2012.NCT01340326Progressive enlargement of the heart chamber and deterioration of contractile function after myocardial infarction (MI), termed post-MI ventricular remodeling, is associated with development of heart failure and poor prognosis [1-3]. The magnitude of post-MI remodeling is influenced by several determinants, most notably infarct size [4], but also by ventricular wall stress [5], patency of infarct-related artery [6], and a number of neurohormonal factors [7]. Thus, the consequence of post-MI remodeling varies among patients with acute MI even in the era of reperfusion therapy [8]. Modification of neurohormonal acitivities, particularly the rennin-angiotensin-aldosterone system (RAAS), can significantly influence the process of ventricular remodeling after acute MI. Suppression of angiotensin activity either by inhibition of angiotensin-converting enzyme (ACE) [9-11] or by blockade of angiotensin II receptor [12]
Efficacies of the new Paclitaxel-eluting Coroflex Please? Stent in percutaneous coronary intervention; comparison of efficacy between Coroflex Please? and Taxus? (ECO-PLEASANT) trial: study rationale and design
Jae-Bin Seo, Hui-Kyung Jeon, Kyung-Woo Park, Jong-Seon Park, Jang-Ho Bae, Sang-Wook Kim, Keon-Woong Moon, Jae-Woong Choi, Sang-Gon Lee, Woo-Young Chung, Tae-Jin Youn, Soo-Joong Kim, Doo-Il Kim, Byung-Ok Kim, Min-Su Hyon, Keum-Soo Park, Tae-Joon Cha, Hweung-Kon Hwang, Seung-Ho Hur, Hyo-Soo Kim
Trials , 2009, DOI: 10.1186/1745-6215-10-98
Abstract: In the comparison of Efficacy between COroflex PLEASe? ANd Taxus? stent(ECO-PLEASANT) trial, approximately 900 patients are being prospectively and randomly assigned to the either type of Coroflex Please? stent and Taxus Liberte? stent via web-based randomization. The primary endpoint is clinically driven target vessel revascularization at 9 months. The secondary endpoints include major cardiac adverse events, target vessel failure, stent thrombosis and angiographic efficacy endpoints.The ECO-PLEASANT trial is the study not yet performed to directly compare the efficacy and safety of the Coroflex Please? versus Taxus Liberte? stent. On the basis of this trial, we will be able to find out whether the Coroflex Please? stent is non-inferior to Taxus Liberte? stent or not.ClinicalTrials.gov number, NCT00699543.Previous randomized trials have shown the efficacy of a slow-release polymeric sirolimus-eluting stent (Cypher?, Cordis, Warren, NJ, USA), paclitaxel-eluting stent (Taxus?, Boston Scientific, Natick, MA, USA), and zotarolimus-eluting stent (Endeavor?, Medtronic, Minneapolis, MN, USA) over bare metal stents in reducing neointimal hyperplasia, late luminal loss, and angiographic restenosis leading to decreased target lesion revascularization [1-11] The Paclitaxel-eluting Coroflex Please? stent is a newly developed drug eluting stent using the Coroflex? stent platform combined with the drug paclitaxel contained in a polymer coating[12]In the PECOPS I, which was one-arm observational study, the results of Coroflex Please? stent were within the range of other Paclitaxel-eluting coronary stents [12,13] Compared with binary restenosis rate of 7.9% in Taxus IV trial, Coroflex? Please stent showed 7.8% of restenosis rate[7] The 3.1% of 30 day MACE rate is within the range of other trials with stents eluting Paclitaxel or Sirolimus. The 6 month MACE rates in PECOPS I were 8.0%, which was similar to 7.8%, and 8.5% in Taxus II MR and SR, respectively[6] In Taxus IV, 9 month f
Anti-Inflammatory Activity of the Methanol Extract of Moutan Cortex in LPS-Activated Raw264.7 Cells
Seung-Chul Chun,Seon Young Jee,Sang Gon Lee,Sook Jahr Park,Jong Rok Lee,Sang Chan Kim
Evidence-Based Complementary and Alternative Medicine , 2007, DOI: 10.1093/ecam/nel093
Abstract: Moutan Cortex (MCE) has been used in traditional medicine to remove heat from the blood, promote blood circulation and alleviate blood stasis. This study was conducted to evaluate the effects of MCE on regulatory mechanisms of cytokines and nitric oxide (NO) involved in immunological activity of Raw264.7 cells. Cells were pretreated with methanolic extracts of MCE, and further cultured for an appropriate time after lipopolyssacharide (LPS) addition. During the entire experimental period, 0.1 and 0.3 mg ml−1 of MCE had no cytotoxicity. In these concentrations, MCE inhibited the production of NO and prostaglandin E2 (PGE2), the expression of inducible NO synthase (iNOS), cyclooxygenase-2 (COX-2) and phosphorylated inhibitor of κBα (p-IκBα), and the activation of nuclear factor κB (NF-κB). MCE also reduced the concentration of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and interleukin-6 (IL-6) in the Raw264.7 cells that were activated by LPS. These results demonstrate that MCE has anti-inflammatory effects through the inhibition of iNOS and COX-2 expression by suppressing the phosphorylation of I-κBα and the activation of NF-κB.
Do Really Close Stomata by Soil Drying ABA Produced in the Roots and Transported in Transpiration Stream?  [PDF]
Joon Sang Lee
American Journal of Plant Sciences (AJPS) , 2013, DOI: 10.4236/ajps.2013.41022
Abstract: Stomatal aperture responses of Commelina communis L. between well watered plants and water stressed plants were investigated. To see the very rapid response to water stress, the plants were directly rooted out from the soil and exposed to the air immediately. Stomata, rooted out from the soil, were totally closed within 10 minutes without any detention time while the stomata of the plants in the soil had been kept opening. These results suggest that stomatal response to the abrupt water stress is very rapid indicating that guard cell itself or leaves could sense water status in the plants.
Transparent Conductive Multilayer Films with Optically Clear Adhesive Interlayer for Touch Panel Devices
Sang Ju Lee,Jae Yong So,Chul Park,Tae Gon Ban
Journal of Applied Sciences , 2010,
Abstract: We synthesized Optically Clear Adhesive (OCA) polymers and tested as an interlayer between two polyethylene terephthalate (PET) films on top of which transparent Indium Tin Oxide (ITO) was deposited. The polymers of OCA was produced from free radical polymerizations by using 2-ethylhexyl acrylate (2-EHA), methyl methacrylate (MMA), Butyl Acrylate (BA), Acrylic Acid (AA) and 2-hydroxy ethyl methacrylate (2-HEMA). Some of fundamental OCA characteristics including Tg, Probe Tack and Peel strength were investigated with the change of MMA and 2-HEMA monomers. The characteristics of ITO coated three layer film were also investigated on the change of RF powder, deposit pressure and heat treatment. These results suggest that the multilayer film using synthesized OCA have the potential to be used in the fabrication of touch panel devices.
Interactive Ion-Mediated Sap Flow Regulation in Olive and Laurel Stems: Physicochemical Characteristics of Water Transport via the Pit Structure
Jeongeun Ryu, Sungsook Ahn, Seung-Gon Kim, TaeJoo Kim, Sang Joon Lee
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0098484
Abstract: Sap water is distributed and utilized through xylem conduits, which are vascular networks of inert pipes important for plant survival. Interestingly, plants can actively regulate water transport using ion-mediated responses and adapt to environmental changes. However, ionic effects on active water transport in vascular plants remain unclear. In this report, the interactive ionic effects on sap transport were systematically investigated for the first time by visualizing the uptake process of ionic solutions of different ion compositions (K+/Ca2+) using synchrotron X-ray and neutron imaging techniques. Ionic solutions with lower K+/Ca2+ ratios induced an increased sap flow rate in stems of Olea europaea L. and Laurus nobilis L. The different ascent rates of ionic solutions depending on K+/Ca2+ ratios at a fixed total concentration increases our understanding of ion-responsiveness in plants from a physicochemical standpoint. Based on these results, effective structural changes in the pit membrane were observed using varying ionic ratios of K+/Ca2+. The formation of electrostatically induced hydrodynamic layers and the ion-responsiveness of hydrogel structures based on Hofmeister series increase our understanding of the mechanism of ion-mediated sap flow control in plants.
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