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Search Results: 1 - 10 of 3727 matches for " Kyung-Sup Yoon "
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Trapa japonica Flerov Extract Attenuates Lipid Accumulation through Downregulation of Adipogenic Transcription Factors in 3T3-L1 Cells  [PDF]
Mi Jin Kim, Kyung Ran Im, Kyung-Sup Yoon
American Journal of Molecular Biology (AJMB) , 2015, DOI: 10.4236/ajmb.2015.52004
Abstract: Obesity is a major human health problem associated with various diseases, including cardiac injury and type 2 diabetes. Trapa japonica Flerov (TJF) has been used in traditional oriental medicine to treat diabetes. In this study, we evaluated the inhibitory effect of and the mechanism underlying the effect of TJF extract on adipogenesis in 3T3-L1 cells. The effects of TJF extract on cell viability were analyzed using a 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide assay, and the anti-adipogenic effect was measured by oil red O staining. The expression of peroxisomal proliferator activated receptor (PPAR)γ, CCAAT/enhancer-binding protein-α (C/EBP)α, adenosine monophosphate-activated protein kinase (AMPK), acetyl-CoA carboxylase (ACC), adiponectin, and fatty acid binding protein (FABP)4 involved in adipogenesis was determined by western blot analysis. TJF extract effectively inhibited lipid accumulation and the expression of PPARγ and C/EBPα in 3T3-L1 cells. TJF also increased the phosphorylation of AMPK and ACC, and decreased the expression of adiponectin and FABP4. These results indicate that TJF extract exerts its anti-obesity effect through the downregulation of adipogenic transcription factors and adipogenic marker genes.
Effect of Hoechunyangkyeok-San Extract on Melanogenesis  [PDF]
Mi Jin Kim, Taek Kyu Jung, Hyun-Chul Park, Kyung-Sup Yoon
Journal of Cosmetics, Dermatological Sciences and Applications (JCDSA) , 2016, DOI: 10.4236/jcdsa.2016.63011
Abstract: Forsythia fructus has been shown to have antioxidative, anti-inflammatory, antibacterial, anti-aging and whitening effects. Hoechunyangkyeok-san (Forsythia viridissima-prescription) is a traditional herbal medicine, which has been clinically used for treating febrile and inflammatory disorders. This work was carried out to investigate the skin whitening effects of Forsythia viridissima-prescription extract (a hydrolyzed extract of Hoechunyangkyeok-san: SID White HYC) on skin. The effects of SID White HYC were assessed the melanin contents in B161 melanoma cells and the pigmented equivalent with HMB45 and Fontana Masson staining in 3D skin model. Then, we examined the expression of major pigment enzymes regulating melanin synthesis and melanosome transport related proteins in B16F1 cells. SID White HYC significantly inhibited the melanin synthesis (56.7% and 30.6% inhibition at 100 μg/mL, intracellular and secreted, respectively) in B16F1 cells and 3D skin model. In addition, western blotting analysis showed that SID White HYC reduced the expression of melanin synthesis and melanosome transport related proteins in B16F1 cells. In clinical trials, the cream containing 0.05% SID White HYC showed skin depigmentation effect without any irritation. These results suggest that SID White HYC may be useful inhibition of melanogenesis and melanosome transport. Therefore, SID White HYC may have potential as a skin-whitening ingredient in cosmetics.
On the Torsion Subgroups of Certain Elliptic Curves over Q  [PDF]
Yoon Kyung Park
Advances in Pure Mathematics (APM) , 2013, DOI: 10.4236/apm.2013.32043
Abstract:

Let E be an elliptic curve over a given number field . By Mordells Theorem, the torsion subgroup of E defined over Q is a finite group. Using Lutz-Nagell Theorem, we explicitly calculate the torsion subgroup E(Q)tors for certain elliptic curves depending on their coefficients.

Computational Design of Binding Proteins to EGFR Domain II
Yoon Sup Choi, Soomin Yoon, Kyung-Lock Kim, Jiho Yoo, Parkyong Song, Minsoo Kim, Young-Eun Shin, Won Jun Yang, Jung-eun Noh, Hyun-soo Cho, Sanguk Kim, Junho Chung, Sung Ho Ryu
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0092513
Abstract: We developed a process to produce novel interactions between two previously unrelated proteins. This process selects protein scaffolds and designs protein interfaces that bind to a surface patch of interest on a target protein. Scaffolds with shapes complementary to the target surface patch were screened using an exhaustive computational search of the human proteome and optimized by directed evolution using phage display. This method was applied to successfully design scaffolds that bind to epidermal growth factor receptor (EGFR) domain II, the interface of EGFR dimerization, with high reactivity toward the target surface patch of EGFR domain II. One potential application of these tailor-made protein interactions is the development of therapeutic agents against specific protein targets.
Performance Analysis and Improvement of WPAN MAC for Home Networks
Saurabh Mehta,Kyung Sup Kwak
Sensors , 2010, DOI: 10.3390/s100402821
Abstract: The wireless personal area network (WPAN) is an emerging wireless technology for future short range indoor and outdoor communication applications. The IEEE 802.15.3 medium access control (MAC) is proposed to coordinate the access to the wireless medium among the competing devices, especially for short range and high data rate applications in home networks. In this paper we use analytical modeling to study the performance analysis of WPAN (IEEE 802.15.3) MAC in terms of throughput, efficient bandwidth utilization, and delay with various ACK policies under error channel condition. This allows us to introduce a K-Dly-ACK-AGG policy, payload size adjustment mechanism, and Improved Backoff algorithm to improve the performance of the WPAN MAC. Performance evaluation results demonstrate the impact of our improvements on network capacity. Moreover, these results can be very useful to WPAN application designers and protocol architects to easily and correctly implement WPAN for home networking.
Optimized planning target volume margin in helical tomotherapy for prostate cancer: is there a preferred method?
Yuan Jie Cao,Suk Lee,Kyung Hwan Chang,Jang Bo Shim,Kwang Hyeon Kim,Min Sun Jang,Won Sup Yoon,Dae Sik Yang,Young Je Park,Chul Yong Kim
Physics , 2015,
Abstract: To compare the dosimetrical differences between plans generated by helical tomotherapy using 2D or 3D margining technique in in prostate cancer. Ten prostate cancer patients were included in this study. For 2D plans, planning target volume (PTV) was created by adding 5 mm (lateral/anterior-posterior) to clinical target volume (CTV). For 3D plans, 5 mm margin was added not only in lateral/anterior-posterior, but also in superior-inferior to CTV. Various dosimetrical indices, including the prescription isodose to target volume (PITV) ratio, conformity index (CI), homogeneity index (HI), target coverage index (TCI), modified dose homogeneity index (MHI), conformation number (CN), critical organ scoring index (COSI), and quality factor (QF) were determined to compare the different treatment plans. Differences between 2D and 3D PTV indices were not significant except for CI (p = 0.023). 3D margin plans (11195 MUs) resulted in higher (13.0%) monitor units than 2D margin plans (9728 MUs). There were no significant differences in any OARs between the 2D and 3D plans. Overall, the average 2D plan dose was slightly lower than the 3D plan dose. Compared to the 2D plan, the 3D plan increased average treatment time by 1.5 minutes; however, this difference was not statistically significant (p = 0.082). We confirmed that 2D and 3D margin plans are not significantly different with regard to various dosimetric indices such as PITV, CI, and HI for PTV, and OARs with tomotherapy.
A Review of Wireless Body Area Networks for Medical Applications  [PDF]
Sana ULLAH, Pervez KHAN, Niamat ULLAH, Shahnaz SALEEM, Henry HIGGINS, Kyung Sup KWAK
Int'l J. of Communications, Network and System Sciences (IJCNS) , 2009, DOI: 10.4236/ijcns.2009.28093
Abstract: Recent advances in Micro-Electro-Mechanical Systems (MEMS) technology, integrated circuits, and wireless communication have allowed the realization of Wireless Body Area Networks (WBANs). WBANs promise unobtrusive ambulatory health monitoring for a long period of time, and provide real-time updates of the patient’s status to the physician. They are widely used for ubiquitous healthcare, entertainment, and military applications. This paper reviews the key aspects of WBANs for numerous applications. We present a WBAN infrastructure that provides solutions to on-demand, emergency, and normal traffic. We further discuss in-body antenna design and low-power MAC protocol for a WBAN. In addition, we briefly outline some of the WBAN applications with examples. Our discussion realizes a need for new power-efficient solu-tions towards in-body and on-body sensor networks.
A Very Low Power MAC (VLPM) Protocol for Wireless Body Area Networks
Niamat Ullah,Pervez Khan,Kyung Sup Kwak
Sensors , 2011, DOI: 10.3390/s110403717
Abstract: Wireless Body Area Networks (WBANs) consist of a limited number of battery operated nodes that are used to monitor the vital signs of a patient over long periods of time without restricting the patient’s movements. They are an easy and fast way to diagnose the patient’s status and to consult the doctor. Device as well as network lifetime are among the most important factors in a WBAN. Prolonging the lifetime of the WBAN strongly depends on controlling the energy consumption of sensor nodes. To achieve energy efficiency, low duty cycle MAC protocols are used, but for medical applications, especially in the case of pacemakers where data have time-limited relevance, these protocols increase latency which is highly undesirable and leads to system instability. In this paper, we propose a low power MAC protocol (VLPM) based on existing wakeup radio approaches which reduce energy consumption as well as improving the response time of a node. We categorize the traffic into uplink and downlink traffic. The nodes are equipped with both a low power wake-up transmitter and receiver. The low power wake-up receiver monitors the activity on channel all the time with a very low power and keeps the MCU (Micro Controller Unit) along with main radio in sleep mode. When a node [BN or BNC (BAN Coordinator)] wants to communicate with another node, it uses the low-power radio to send a wakeup packet, which will prompt the receiver to power up its primary radio to listen for the message that follows shortly. The wake-up packet contains the desired node’s ID along with some other information to let the targeted node to wake-up and take part in communication and let all other nodes to go to sleep mode quickly. The VLPM protocol is proposed for applications having low traffic conditions. For high traffic rates, optimization is needed. Analytical results show that the proposed protocol outperforms both synchronized and unsynchronized MAC protocols like T-MAC, SCP-MAC, B-MAC and X-MAC in terms of energy consumption and response time.
A Study of IEEE 802.15.4 Security Framework for Wireless Body Area Networks
Shahnaz Saleem,Sana Ullah,Kyung Sup Kwak
Sensors , 2011, DOI: 10.3390/s110201383
Abstract: A Wireless Body Area Network (WBAN) is a collection of low-power and lightweight wireless sensor nodes that are used to monitor the human body functions and the surrounding environment. It supports a number of innovative and interesting applications, including ubiquitous healthcare and Consumer Electronics (CE) applications. Since WBAN nodes are used to collect sensitive (life-critical) information and may operate in hostile environments, they require strict security mechanisms to prevent malicious interaction with the system. In this paper, we first highlight major security requirements and Denial of Service (DoS) attacks in WBAN at Physical, Medium Access Control (MAC), Network, and Transport layers. Then we discuss the IEEE 802.15.4 security framework and identify the security vulnerabilities and major attacks in the context of WBAN. Different types of attacks on the Contention Access Period (CAP) and Contention Free Period (CFP) parts of the superframe are analyzed and discussed. It is observed that a smart attacker can successfully corrupt an increasing number of GTS slots in the CFP period and can considerably affect the Quality of Service (QoS) in WBAN (since most of the data is carried in CFP period). As we increase the number of smart attackers the corrupted GTS slots are eventually increased, which prevents the legitimate nodes to utilize the bandwidth efficiently. This means that the direct adaptation of IEEE 802.15.4 security framework for WBAN is not totally secure for certain WBAN applications. New solutions are required to integrate high level security in WBAN.
On The Development of Low-power MAC Protocol for WBANs
Sana Ullah,Pervez Khan,Kyung Sup Kwak
Lecture Notes in Engineering and Computer Science , 2009,
Abstract:
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