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Search Results: 1 - 10 of 20463 matches for " Dongkyun Kim "
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Energy-Efficient Data Gathering Techniques Using Multiple Paths for Providing Resilience to Node Failures in Wireless Sensor Networks
Joungsik Kim,Dongkyun Kim
Journal of Communications , 2006, DOI: 10.4304/jcm.1.3.21-28
Abstract: Multiple paths have been used to provide loadbalancing of traffic and resilience to node failures in mobile ad-hoc networks or sensor networks. In addition, the energy expenditure can be distributed among nodes over the multiple paths. However, most existing multi-path routing protocols require their complex procedures such as local repair or periodic reconstruction of the multiple paths, during which much loss of packet is even experienced. In this paper, we therefore propose two versions of an Energy efficient Data Gathering technique using Multiple paths (EDGM), which are more suitable for highly populated wireless sensor networks in terms of having more simple and resilient features than other existing techniques. One of them is to make use of the multiple shortest paths strictly. The other is to use a neighbor node’s path towards the sink node at the expense of using much longer paths to provide more resilience to node failures. By simulation using ns-2simulator, we prove that EDGM versions achieve two goals satisfactorily: energy-saving and resilience to node failure.
An Energy Efficient Localization-Free Routing Protocol for Underwater Wireless Sensor Networks
Abdul Wahid,Dongkyun Kim
International Journal of Distributed Sensor Networks , 2012, DOI: 10.1155/2012/307246
Abstract: Recently, underwater wireless sensor networks (UWSNs) have attracted much research attention from both academia and industry, in order to explore the vast underwater environment. UWSNs have peculiar characteristics; that is, they have large propagation delay, high error rate, low bandwidth, and limited energy. Therefore, designing network/routing protocols for UWSNs is very challenging. Also, in UWSNs, improving the energy efficiency is one of the most important issues since the replacement of the batteries of underwater sensor nodes is very expensive due to the unpleasant underwater environment. In this paper, we therefore propose an energy efficient routing protocol, named (energy-efficient depth-based routing protocol) EEDBR for UWSNs. EEDBR utilizes the depth of sensor nodes for forwarding data packets. Furthermore, the residual energy of sensor nodes is also taken into account in order to improve the network lifetime. Based on the comprehensive simulation using NS2, we observe that EEDBR contributes to the performance improvements in terms of the network lifetime, energy consumption, and end-to-end delay. A previous version of this paper was accepted in AST-2011 conference.
A Secure Cluster Formation Scheme in Wireless Sensor Networks
Gicheol Wang,Dongkyun Kim,Gihwan Cho
International Journal of Distributed Sensor Networks , 2012, DOI: 10.1155/2012/301750
Abstract: In wireless sensor networks, clustering expedites many desirable functions such as load balancing, energy savings, and distributed key management. For secure clustering, it is very important to find compromised nodes and remove them during the initial cluster formation process. If some nodes are compromised and survive the censorship process, they can make some nodes have a different cluster view and can split a cluster into multiple clusters to deteriorate cluster quality as a whole. To resolve these problems, we propose a robust scheme against such attacks in this paper. First, our scheme generates large-sized clusters where any two nodes are at most two hops away from each other to raise the quality of clusters. Second, our scheme employs the verification of two-hop distant nodes to preserve the quality of the large-sized clusters and refrains from splitting the clusters. Last, our scheme prefers broadcast transmissions to save the energy of nodes. Security analysis proves that our scheme can identify compromised nodes and preserves the cluster membership agreement against the compromised nodes. In addition, simulation results prove that our scheme generates fewer clusters and is more secure and energy efficient than the scheme producing only small-sized clusters.
A scalable multi-sink gradient-based routing protocol for traffic load balancing
Yoo Hongseok,Shim Moonjoo,Kim Dongkyun
EURASIP Journal on Wireless Communications and Networking , 2011,
Abstract: Wireless sensor networks have been assumed to consist of a single sink and multiple sensor nodes which do not have mobility. In these networks, sensor nodes near the sink dissipate their energy so fast due to their many-to-one traffic pattern, and finally they die early. This uneven energy depletion phenomenon known as the hot spot problem becomes more serious as the number of sensor nodes (i.e., their scale) increases. Recently, multi-sink wireless sensor networks have been envisioned to solve the hot spot problem. Gradient routing protocols are known to be appropriate for the networks in that network traffic is evenly distributed to multiple sinks to prolong network lifetime and they are scalable. Each node maintains its gradient representing the direction toward a neighbor node to reach one of the sinks. In particular, existing protocols allow a sensor node to construct its gradient using the cumulative traffic load of a path for load balancing. However, they have a critical drawback that a sensor node cannot efficiently avoid using the path with the most overloaded node. Hence, this paper introduces a new Gradient routing protocol for LOad-BALancing (GLOBAL) with a new gradient model to maximize network lifetime. The proposed gradient model considers both of the cumulative path load and the traffic load of the most overloaded node over the path in calculating each node's gradient value. Therefore, packets are forwarded over the least-loaded path, which avoids the most overloaded node. In addition, it is known that assigning a unique address to each sensor node causes much communication overhead. Since the overhead increases as the network scales, routing protocols using an address to indicate the receiver in forwarding a packet are not scalable. Thus, GLOBAL also includes an addressing-free data forwarding strategy. Through ns-2 simulation, we verify that GLOBAL achieves better performance than the shortest path routing and load-aware gradient routing ones.
Data Disseminations in Vehicular Environments
Dongkyun Kim,Juan Carlos Cano,Wei Wang,Floriano De Rango,Kun Hua
International Journal of Distributed Sensor Networks , 2013, DOI: 10.1155/2013/291635
Abstract:
Roles of TLR7 in Activation of NF-κB Signaling of Keratinocytes by Imiquimod
Zheng Jun Li, Kyung-Cheol Sohn, Dae-Kyoung Choi, Ge Shi, Dongkyun Hong, Han-Eul Lee, Kyu Uang Whang, Young Ho Lee, Myung Im, Young Lee, Young-Joon Seo, Chang Deok Kim, Jeung-Hoon Lee
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0077159
Abstract: Imiquimod is known to exert its effects through Toll-like receptor 7 (TLR7) and/or TLR8, resulting in expression of proinflammatory cytokines and chemokines. Keratinocytes have not been reported to constitutively express TLR7 and TLR8, and the action of imiquimod is thought to be mediated by the adenine receptor, not TLR7 or TLR8. In this study, we revealed the expression of TLR7 in keratinocytes after calcium-induced differentiation. After addition of calcium to cultured keratinocytes, the immunological responses induced by imiquimod, such as activation of NF-κB and induction of TNF-α and IL-8, were more rapid and stronger. In addition, imiquimod induced the expression TLR7, and acted synergistically with calcium to induce proinflammatory cytokines. We confirmed that the responses induced by imiquimod were significantly inhibited by microRNAs suppressing TLR7 expression. These results suggest that TLR7 expressed in keratinocytes play key roles in the activation of NF-κB signaling by imiquimod, and that their modulation in keratinocytes could provide therapeutic potential for many inflammatory skin diseases.
Spectrally Encoded Confocal Microscopy for Guiding Lumpectomy
Elena F. Brachtel,Barbara L. Smith,Guillermo J. Tearney,Dongkyun Kang
Analytical Cellular Pathology , 2014, DOI: 10.1155/2014/573851
Abstract:
Design of Quantification Model for Ransom Ware Prevent  [PDF]
Donghyun Kim, Seoksoo Kim
World Journal of Engineering and Technology (WJET) , 2015, DOI: 10.4236/wjet.2015.33C030
Abstract:

The growth of ICT within the society has become increasingly digitized, thus, the overall activity has amounted to various researches for protecting any data from malicious threats. Recently, ransomware has been a rapidly propagated subject for social engineering techniques especially the ransomware. Users can delete a ransomeware code using an antivirus software code. However, the encrypted data would be impossible to recover. Therefore, ransomware must be prevented and must have early detection before it infects any data. In this paper, we are proposing a quantification model to prevent and detect any cryptographic operations in the local drive.

Trends of Noninvasive Radiofrequency and Minimally Invasive Treatment for the Management of Facial Aging  [PDF]
Sunghee Kim, Moonjong Kim
Journal of Cosmetics, Dermatological Sciences and Applications (JCDSA) , 2019, DOI: 10.4236/jcdsa.2019.91003
Abstract: Various treatments for the management of facial aging have been performed among which noninvasive radio-frequency (RF; i.e., thermage) treatment and minimally invasive treatments are on the rise. The purpose of this study was to analyze trends of the treatment of facial aging in Korea and to investigate relationships between the use of noninvasive RF and minimally invasive treatments. A retrospective analysis conducted on data from 4021 patients showed that thermage treatment increased by 134.9% over 5 years. As a person ages, the rate of facial treatment with both the botulinum toxin (for the masseter and lines of the glabella, lateral canthus, and forehead) and the PDO thread lift increases. The use of the treatments, nasolabial fold filler and Silhouette Soft Thread, however, was not associated with aging. The patients receiving thermage treatment were less likely to undergo any of the other treatments including PDO thread lift, Silhouette Soft Thread, nasolabial fold filler, or any of the botulinum toxin treatments. Overall, the results showed that patients who had received noninvasive RF tended to receive less minimally invasive treatment.
The Effect of Prunella on Anti-Inflammatory Activity in RAW264.7 Mouse Macrophage Cells  [PDF]
Meehye Kim
Food and Nutrition Sciences (FNS) , 2012, DOI: 10.4236/fns.2012.39170
Abstract: The extracts of Prunella vulgaris L. (Labiatae), a popular Western and Chinese herbal medicine, was shown to have anti-inflammatory properties, which might be due to partially, their rosmarinic acid content. Inhition of prostaglandine E2 (PGE2) production in lipopolysaccharide (LPS) stimulated RAW264.7 mouse macrophage cells was assessed with an enzyme immunoassay (EIA) following 8-hour treatments with Prunella vulgaris extracts or fractions. Results showed that 95% ethanol extracts from P. vulgaris significantly inhibited PGE2 production. In further studies, fraction 2 from the 95% ethanol extract of P. vulgaris significantly reduced PGE2 production at 66 µg/ml (72% reduction). Cytotoxic-ity did not play a role in the noted reduction of PGE2 seen in either the extracts or fractions from P. vulgaris. High performance liquid chromatography analysis showed that there was 1.4 mM rosmarinic acid in 95% ethanol Prunella extract (201 mg/ml crude extract). Our results suggest that rosmarinic acid may contribute toward the anti-inflammatory activity of Prunella in a dose-response manner. Prunella might have a potential to be used as a functional food for anti-inflammatory activity.
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