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Enhanced CCA Scheme for Slotted CSMA/CA in IEEE 802.15.4 LR-WPANs
AHN, Saeyoung,KIM, Wook,AN, Sunshin The Institute of Electronics, Information and Comm 2011 IEICE TRANSACTIONS ON COMMUNICATIONS - Vol.eb94 No.4
<P>Recently, IEEE 802.15.4 has been standardized for WSNs (Wireless Sensor Networks). This paper proposes an enhanced CCA scheme which involves the data transmission device sending a notifyBusyChannel (nBC) signal in the backoff period when the Channel Using Quotient (CUQ) exceeds 0.5. The CUQ stands for the rate of channel utilization in the previous slot duration. In a single CCA operation, the device nodes are made aware of the busy status of the channel by the nBC signal. We implement the ECCA scheme in a hardware chip for a performance evaluation. The results show that the proposed scheme has short queuing times and less energy consumption than IEEE 802.15.4 CCA. And the scheme is compatible with conventional IEEE 802.15.4 devices.</P>
Logical Position Exchange Algorithm for Efficient Management in ZigBee Tree Networks
AHN, Saeyoung,AN, Sunshin The Institute of Electronics, Information and Comm 2010 IEICE TRANSACTIONS ON COMMUNICATIONS - Vol.93 No.12
<P>Currently, there are various routing methods that consider the energy in a wireless sensor environment. The algorithm we consider is a low-rate wireless personal area network, viz., 802.15.4, and ZigBee routing network. Considering, the overall organization of the network energy efficiency, we suggest a logical position exchange (LPE) algorithm between specified nodes. Logical positioning means connecting high sub-networks and low sub-networks based on the neighbor nodes information of the address ID, and depth in the ZigBee tree topology network. When one of the nodes of the tree topology network, which is responsible for connecting multiple low sub-networks and high sub-networks, has difficulty performing its important roles in the network, because of energy exhaustion, it exchanges essential information and entrusts logical positioning to another node that is capable of it. A partial change in the logical topology enhances the energy efficiency in the network.</P>
Park, Saeyoung,Choi, Yoonyoung,Jung, Namhee,Kim, Jieun,Oh, Seiyoon,Yu, Yeonsil,Ahn, Jung-Hyuck,Jo, Inho,Choi, Byung-Ok,Jung, Sung-Chul D.A. Spandidos 2017 International journal of molecular medicine Vol.39 No.4
<P>Mesenchymal stem cells (MSCs) are capable of self-renewal and differentiation and are thus a valuable source for the replacement of diseased or damaged organs. Previously, we reported that the tonsils can be an excellent reservoir of MSCs for the regeneration of skeletal muscle (SKM) damage. However, the mechanisms involved in the differentiation from tonsil-derived MSCs (T-MSCs) to myocytes via myoblasts remain unclear. To clarify these mechanisms, we analyzed gene expression profiles of T-MSCs during differentiation into myocytes compared with human skeletal muscle cells (hSKMCs). Total RNA was extracted from T-MSCs, T-MSC-derived myoblasts and myocytes, and hSKMCs and was subjected to analysis using a microarray. Microarray analysis of the three phases of myogenic differentiation identified candidate genes associated with myogenic differentiation. The expression pattern of undifferentiated T-MSCs was distinguishable from the myogenic differentiated T-MSCs and hSKMCs. In particular, we selected FNBP1L, which among the upregulated genes is essential for antibacterial autophagy, since autophagy is related to SKM metabolism and myogenesis. T-MSCs differentiated toward myoblasts and skeletal myocytes sequentially, as evidenced by increased expression of autophagy-related markers (including Beclin-1, LC3B and Atg5) and decreased expression of Bcl-2. Furthermore, we reconfirmed that autophagy has an effect on the mechanism of skeletal myogenic differentiation derived from T-MSCs by treatment with 5-azacytidine and bafilomycin A1. These data suggest that the transcriptome of the T-MSC-derived myocytes is similar to that of hSKMCs, and that autophagy has an important role in the mechanism of myogenic differentiation of T-MSCs.</P>
Hoon Lee,Saeyoung Ahn,Changwon Lee,Hongbae Kim,Jein Jeong,Taigun Im 한국물리학회 2004 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.44 No.52
Platinum (Pt) is a biocompatible material which exhibits strong thermal and electrical conductivity due to its high melting point and good durability. Thus, it is used commonly in bio-electrodes and bio-chips. In this study, a tungsten (W) wire was coated with a platinum lm and was analyzed for its mechanical and biocompatibility properties. The platinum lm was deposited by magnetron sputtering with an UnBalanced Magnetic (UBM) eld system. The experiment was performed under a variety of conditions by changing the deposition temperature, the bias voltage, the magnetic eld and the deposition time in order to deduce the optimum conditions. We examined the exfoliation and the sedimentation states of the anode and the cathode by using microscope and an electron probe microanalysis (EPMA) for the electro-chemical corrosion test using the Hank's solution. The lm showed a very low impurity level, and the surface and the cross section of the lm appeared elaborate. No sedimentation appeared in the lm, and the crystallization in the (110), the (200), the (220) and the (222) directions observed. However, at a high current density (800 mA/cm2), sedimentation was observed in the corrosion test.
Energy Efficient Topology Control based on Sociological Cluster in Wireless Sensor Networks
( Sangwook Kang ),( Sangbin Lee ),( Saeyoung Ahn ),( Sunshin An ) 한국인터넷정보학회 2012 KSII Transactions on Internet and Information Syst Vol.6 No.1
The network topology for a wide area sensor network has to support connectivity and a prolonged lifetime for the many applications used within it. The concepts of structure and group in sociology are similar to the concept of cluster in wireless sensor networks. The clustering method is one of the preferred ways to produce a topology for reduced electrical energy consumption. We herein propose a cluster topology method based on sociological structures and concepts. The proposed sociological clustering topology (SOCT) is a method that forms a network in two phases. The first phase, which from a sociological perspective is similar to forming a state within a nation, involves using nodes with large transmission capacity to set up the global area for the cluster. The second phase, which is similar to forming a city inside the state, involves using nodes with small transmission capacity to create regional clusters inside the global cluster to provide connectivity within the network. The experimental results show that the proposed method outperforms other methods in terms of energy efficiency and network lifetime.
김범진(Bumjin Kim),안세영(Saeyoung Ahn),안순신(Sunshin An) 한국정보과학회 2008 한국정보과학회 학술발표논문집 Vol.35 No.2
실내 환경에서는 GPS를 이용하여 이동 물체의 위치를 인식하기가 어렵다. 본 논문에서는 실내 환경에서 전송 세기의 조절이 가능한 레퍼런스 노드를 이용하여 모바일 노드의 위치를 인식하는 방법을 제안한다. 이 위치 인식 방법은 이론적인 오차 범위를 제공하고 에너지 소비를 줄이며, 위치 인식 시스템의 경제성을 향상 시키기 위해 위치 테이블을 사용한다. 즉, 본 논문은 레퍼런스 노드들의 간격 및 특정 간격에서의 위치 테이블 형성 알고리즘에 대한 것으로, 레퍼런스 노드들의 간격에 따른 위치 테이블의 크기, 오차 범위 등에 대한 변화를 분석한다.
Bonghan Ducts as Possible Pathways for Cancer Metastasis
유정선,Hong Bae Kim,오가이,이병천,Saeyoung Ahn,소광섭 사단법인약침학회 2009 Journal of Acupuncture & Meridian Studies Vol.2 No.2
Abstract Objective: The present study has been designed to find a possible new route for the metastasis of cancer cells on the fascia surrounding tumor tissue using a novel technique of trypan blue staining. Materials and Methods: Tumor tissues were grown in the skin of nude mice after subcutaneous inoculation with human lung cancer cells. Trypan blue was recently identified as a dye with specificity for Bonghan ducts (BHDs) and not other tissues, such as blood or lymph vessels or nerves. Results: We demonstrate that the trypan blue staining technique allows the first visualization of BHDs which are connected to tumor tissues. Conclusion: Since BHDs are known to make up a circulatory system corresponding to acu puncture meridians or collaterals, we propose that, in addition to the currently known blood or lymph vessels, BHDs on tumor tissue fascia may be a novel pathway for metastasis.
Kim, Jungdae,Lim, Jaekwan,Kim, Hongbae,Ahn, Saeyoung,Sim, Sung-Bo,Soh, Kwang-Sup Taylor Francis 2006 Electromagnetic biology and medicine Vol.25 No.2
<P>A scanning system for the detection of spontaneous ultraweak photon emission from nude mice with transplanted tumors is presented. A photomultiplier tube (PMT) with an effective area of 15 mm diameter was used for measuring photon emission in a wavelength range from 300 to 650 nm. Tumors were induced in nude mice by transplantation of an ovarian cancer cell line into the back of mice. The PMT was moved for scanning over the whole body of a mouse placed in a dark box. The profiles of the intensities of photon emissions from the tumor mice are presented and compared with those obtained from the control mice.</P>