• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.12B
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• pp.1028-1036
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• 2006

Energy conservation is an important issue in wireless networks, especially for self-organized, low power, low data-rate impulse-radio ultra-wideband (IR-UWB) networks, where every node is a battery-driven device. To conserve energy, it is necessary to turn node into sleep state when no data exist. This paper addresses the energy consumption analysis of Direct-Sequence (DS) versus Time-Hopping (TH) multiple accesses and two kinds of sleeping protocols (slotted and unslotted) in PHY-MAC for Un networks. We introduce an analytical model for energy consumption or a node in both TH and DS multiple accesses and evaluate the energy consumption comparison between them and also the performance of the proposed sleeping protocols. Simulation results show that the energy consumption per packet of DS case is less than TH case and for slotted sleeping is less than that of unslotted one for bursty load case, but with respect to the load access delay unslotted one consumes less energy, that maximize node lifetime.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.4B
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• pp.559-565
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• 2010

In Mobile IPv6 handover should be followed by RO(Route Optimization) to support direct communication between a MN(Mobile Node) and CN(Correspondent Node). For this RR MIPv6 must perform RR(Return Routability) procedure before BU(Binding Update) to CN. The Fast Handover for MIPv6(FMIPv6) also performs the RR test for MN to communicate with CN directly. However, Return Routability test has long latency resulting in handover delay in MIPv6. This paper proposes the method to reduce the handover deay by reducing RO latency in FastMobile IPv6.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.7B
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• pp.659-667
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• 2009

Mobile Ad-hoc Network consists of mobile nodes without immobile base station. In mobile ad-hoc network, network cutting has occurred frequently in node because of energy restriction and frequent transfer of node. Therefore, it requires research for certain techniques that react softly in topology alteration in order to improve reliability of transmission path. This paper proposes path selection techniques to consider mobility of node that respond when search path using AOMDV routing protocol. As applying proposed techniques, We can improve reliability and reduce re-searching number of times caused by path cutting.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.3B
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• pp.123-134
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• 2008

In this paper, a routing algorithm for wireless sensor networks is proposed to improve the efficiency of energy consumption in sensor nodes. Each sensor node has the value called ‘Flooding Level’ obtained through the initial flooding from a sink node instead of sending beacon messages in multi-hop sensor field. This value can be used for guaranteeing the sensor nodes to connect with a sink node and determining the roles of cluster-head and cluster-gateway node efficiently and simply during the clustering. If different algorithms are added to our protocol, it will work better in the side of energyefficiency. This algorithm is evaluated through analysis and extensive simulations.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.5B
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• pp.253-259
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• 2008

Because a sensor node in wireless sensor networks is battery operated and energy constrained, reducing energy consumption of each node is one of important issues. The clustering technique can make network topology be hierarchical and reduce energy consumption of each sensor node. In this paper, we propose an efficient clustering mechanism considering overlap avoidance in wireless sensor networks. The proposed method consists of three parts. The first is to elect cluster heads considering each node's energy. Then clusters are formed by using signal strength in the second phase. Finally we can reduce the cluster overlap problem derived from two or more clusters. In addition, this paper includes performance evaluation of our algorithm. Simulation results show that network lifetime was extended up to 75 percents than LEACH and overlapped clusters are decreased down to nearly zero percents.

• Korean Journal of Head & Neck Oncology
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• v.32 no.2
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• pp.35-39
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• 2016

Castleman's disease (CD) is an uncommon lymphoproliferative disorder. The disease entity is classified into 2 clinical subtypes, unicentric and multicentric type. Prevalence of lymphoid malignancy in multicentric CD (MCD) is very low. In this case, we report a case of 77 years old woman who developed high fever and swelling in both side of her neck. Neck lymph node biopsy revealed plasma cell hyperplasia. Patient's symptom was subsided after treatment with Dexamethasone. Three months later, multiple lymph node enlargement was developed in abdomen and neck area again. Repeated neck lymph node biopsy confirmed diffuse large B cell lymphoma. The patient started chemotherapy.

• Journal of KIISE:Databases
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• v.27 no.2
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• pp.216-226
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• 2000

This paper suggests a new access path, hashed B-tree which is an efficient access method for integrity checking. Hashed B-tree is based on the observation that most query patterns in enforcing integrity constraints are point queries. Hashed B-tree compresses the key by hashing procedure, which reduces the height of tree and results in fast node search. This method has the advantages such as it can be implemented easily and use the B-tree concurrency control and recovery algorithm with minor modifications.

• Journal of Practical Agriculture & Fisheries Research
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• v.13 no.1
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• pp.71-82
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• 2011

This study was conducted to investigate the effect of stem node number, pinching time and growth retardants on the growth of Coreopsis spp. and Dianthus spp. Thy day of seedings are not passed period of 4 weeks after seedlings in the Cutting number and the days seedlings of joint experiments of Coreopsis spp. 2 node ranches treatment of Coreopsis spp. are reasonable valuable as ornamental pot product. Pinching time of Coreopsis spp. was more effectiveis on lateral and growth inhibition in the two times pinching treatment. It is observed that plant growth inhibitors was affected the growth of Coreopsis spp. It is observed that B-9 treatment is the effective plants growth and differentiation, especially the 2 times treatment with 4,000 ppm was the most effective. On the other hand, CCC treatment showed significant differences. B-9 treatment of Coreopsis spp was more effectived than the other treatment. Pinching and plant growth inhibitors of Dianthus spp. was not good the growth and plant height. Compared with B-9 4,000 ppm 2 times and control increased leaves extremely. it confirmed that the things are positively affective.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.12B
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• pp.1535-1541
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• 2009

In this paper, we suggest an efficient path searching algorithm that reduces the hop count when each node sends a data in ZigBee networks. As the hop count reduces, the network traffic is also reduces and leads to less energy consumption. This enables the sensor network live longer with limited node power. The proposed path searching algorithm consists of two sub-algorithms. One for upstream process and the other for downstream process. When a node selects its proper routing path, the node not only uses the information of the parent and child node, but it also uses the neighbor nodes for each node. In the simulation, we changed various network environment factors such as network parameters, number of nodes, and number of neighbor nodes and observed their performances. We compare the performance to the previous ZigBee Tree routing algorithm with separate two algorithms, the upstream and the downstream, and then compare the performance when all two algorithms are applied.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.10B
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• pp.955-963
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• 2009

In this paper, we propose a medium access control(MAC) protocol for reducing the energy efficiency and for improving the transmission efficiency in underwater acoustic sensor networks. In underwater environment, the transmission delay is longer and bandwidth is smaller than terrestrial environment. Considering these points, we propose a new MAC protocol to enhance throughput and to manage efficiently the energy of nodes. The proposed protocol operates as a channel reservation scheme to decrease data collisions, and uses a mechanism to control the hidden node problem and the exposed node problem occurred in ad hoc networks. The proposed protocol consists of the slotted based transmission frame and reduces data collisions between nodes by putting separately the reservation period in the transmission frame. In addition, it is able to solve the hidden node problem and the exposed node problem by reservation information between nodes. We carry out the simulation to evaluate the proposed protocol in terms of the average energy consumption, the ratio of collision, throughput, and the average transmission delay, and compare the proposed protocol to a traditional MAC protocol in the underwater environment. The simulation results show that the proposed protocol outperforms the traditional protocol under a various of network parameters.