• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.11 no.4
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• pp.1-8
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• 2007

In some wireless sensor networks, the sensor nodes are required to be located sparsely at designated positions over a wide area, introducing the problem of adding minimum number of relay nodes to interconnect the sensor nodes. The problem finds its a bstract form in literature: the Minimum number of Steiner Points. Since it is known to be NP-hard, this paper proposes an approximation scheme to estimate the minimum number of relay nodes through the properties of the abstract form. Note that by reducing the numb er of nodes in a sensor network, the amount of data exchange over the net will be far decreased.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.17
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• pp.7049-7054
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• 2014

Background: Almost half of the breast cancer patients with positive sentinel lymph nodes have no additional disease in the remaining axillary lymph nodes. This group of patients do not benefit from complete axillary lymph node dissection. This study was designed to assess the clinicopathologic factors that predict non-sentinel lymph node metastasis in Iranian breast cancer patients with positive sentinel lymph nodes. Materials and Methods: The records of patients who underwent sentinel lymph node biopsy, between 2003 and 2012, were reviewed. Patients with at least one positive sentinel lymph node who underwent completion axillary lymph node dissection were enrolled in the present study. Demographic and clinicopathologic characteristics including age, primary tumor size, histological and nuclear grade, lymphovascular invasion, perineural invasion, extracapsular invasion, and number of harvested lymph nodes, were evaluated. Results: The data of 167 patients were analyzed. A total of 92 (55.1%) had non-sentinel lymph node metastasis. Univariate analysis of data revealed that age, primary tumor size, histological grade, lymphovascular invasion, perineural invasion, extracapsular invasion, and the number of positive sentinel lymph nodes to the total number of harvested sentinel lymph nodes ratio, were associated with non-sentinel lymph node metastasis. After logistic regression analysis, age (OR=0.13; 95% CI, 0.02-0.8), primary tumor size (OR=7.7; 95% CI, 1.4-42.2), lymphovascular invasion (OR=19.4; 95% CI, 1.4-268.6), extracapsular invasion (OR=13.3; 95% CI, 2.3-76), and the number of positive sentinel lymph nodes to the total number of harvested sentinel lymph nodes ratio (OR=20.2; 95% CI, 3.4-121.9), were significantly associated with non-sentinel lymph node metastasis. Conclusions: According to this study, age, primary tumor size, lymphovascular invasion, extracapsular invasion, and the ratio of positive sentinel lymph nodes to the total number of harvested sentinel lymph nodes, were found to be independent predictors of non-sentinel lymph node metastasis.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.5
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• pp.1049-1056
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• 2010

Recently RFID system has been adopted in various fields rapidly. However, we should solve the problem of privacy invasion that can be occurred by obtaining information of RFID Tag without any permission for popularization of RFID system. To solve these problems, There is the Ohkubo et al.'s Hash-Chain Scheme which is the safest method. However, this method has a problem that requesting lots of computing process because of creasing numbers of Tag. Therefore We, suggest SP-Division algorithm satisfied with all necessary security of Privacy Protection Scheme and decreased in Tag Identification Time in this paper. And this paper implemented it in time standard finding the first key among the data devided into each nodes. The length of Hash-Chain holds 1000, and the total number of SPs increases 1000, 2000, 3000, and 4000. Comparing tag identification time by the total number of SPs and the number of Nodes with single node, extending the number of nodes to 1, 2, 3 and 4, when the number of nodes is 2, 40% of Performance, when the number of nodes is 3, 56%, and when the number of nodes is 4, 71% is improved.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.44 no.1
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• pp.41-48
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• 2007

In this paper, we propose an optimal placement of sensor nodes with 2.4GHz wireless channel characteristics. The proposed method determines optimal transmission range based on log-normal path loss model, and optimal number of sensor nodes calculating the density of sensor nodes. For the lossless data transmission, we search the optimal locations with self-organizing feature maps(SOM) using transmission range, and number of sensor nodes. We demonstrate that optimal transmission range is 20m, and optimal number of sensor nodes is 8. We performed simulations on the searching for optimal locations and confirmed the link condition of sensor nodes.

• Journal of Gastric Cancer
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• v.9 no.4
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• pp.246-255
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• 2009

Purpose: The objectives of this study were to investigate the impact of the number of resected lymph nodes on the survival of gastric cancer patients who underwent curative resection, and to evaluate the cut-off values that can have an influence on survival on the tumor stage-stratified analysis. Materials and Methods: The subjects were 949 gastric cancer patients who underwent curative resection at Korea University Medical Center from 1992 to 2002. They were classified according to the depth of tumor invasion, and the influence of the number of resected lymph nodes on survival was investigated. The cut-off value for the number of resected lymph nodes was determined as the smallest value that showed a significant survival difference. Results: The tumor size, location, lymph node stage, the number of metastatic lymph nodes and the number of resected lymph nodes were significantly different according to the tumor stage. The average number of resected lymph nodes was about 39, and it showed linear correlation with the number of metastatic lymph nodes. On the Cox proportional hazard model, the cut-off values of the number of resected lymph nodes, as corrected by the number of metastatic lymph nodes, was 14 for all the patients, 15 for the pT1 patients, 28 for the pT2 patients and 37 for the pT3 patients, respectively. Conclusion: Retrieving a number of lymph nodes that is more than the cut-off value could improve the survival of gastric cancer patients. Surgeons should also make efforts to perform an exact and thorough D2 lymph node dissection. Therefore, we urge surgeons to perform D2 dissection and pathologists should examine an certain exact number of lymph nodes.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.9B
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• pp.1775-1784
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• 1999

This paper proposes a method of removing unnecessary hidden nodes by a new cost function that evaluates the variance and the mean of hidden node outputs during training. The proposed cost function makes necessary hidden nodes be activated and unnecessary hidden nodes be constants. We can remove the constant hidden nodes without performance degradation. Using the CEDAR handwritten digit recognition, we have shown that the proposed method can remove the number of hidden nodes up to 37.2%, with higher recognition rate and shorter learning time.

• Journal of information and communication convergence engineering
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• v.10 no.4
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• pp.329-336
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• 2012

For designing broadcast protocols in mobile ad hoc networks (MANETs), one of the important goals is to reduce the rebroadcast packets redundancy while reaching all the nodes in network. In this paper, we propose a probabilistic broadcasting mechanism based on selfishness and additional coverage in MANETs. Our approach dynamically adjusts the rebroadcast probability according to the extra covered area and number of neighbor nodes. By these two factors, mobile hosts can be classified into three groups: normal, low selfishness, and high selfishness groups. The nodes in the normal group forward packets for other nodes with high probability, whereas the nodes in the low selfishness group rebroadcast packets with low probability and the nodes in the high selfishness group do not rebroadcast packets. We compared our approach with simple flooding and the fixed probabilistic approach. The simulation results show that the proposed schemes can significantly reduce the number of retransmissions by up to 40% compared simple flooding and fixed probabilistic scheme without significant reduction in the network reachability and end-to-end packet delay.

• ETRI Journal
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• v.27 no.1
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• pp.1-12
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• 2005

We propose a heuristic buffer management scheme that uses both positive and negative acknowledgments to provide scalability and reliability. Under our scheme, most receiver nodes only send negative acknowledgments to their repair nodes to request packet retransmissions while some representative nodes also send positive acknowledgments to indicate which packets can be discarded from the repair node's buffer. Our scheme provides scalability because it significantly reduces the number of feedbacks sent by the receiver nodes. In addition, it provides fast recovery of transmission errors since the packets requested from the receiver nodes are almost always available in their buffers. Our scheme also reduces the number of additional retransmissions from the original sender node or upstream repair nodes. These features satisfy the original goal of treebased protocols since most packet retransmissions are performed within a local group.

• International journal of advanced smart convergence
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• v.6 no.1
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• pp.57-67
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• 2017

In this paper, propose an algorithm to improve network lifetime by equally consuming energy of LEACH - Mobile sensor nodes. LEACH is one of energy efficient protocols. However, we did not consider the mobility of nodes. Therefore, the transmission reception success rate of the moving data is reduced. LEACH-Mobile is a protocol that has improved the drawbacks of these LEACH. However, since LEACH-Mobile has a larger number of data packets and consumes more energy than LEACH, it has a disadvantage that the lifetime of the network is short. In order to improvement these disadvantage, Based on the average of the remaining energy of the node, cluster heads are elected with a number of nodes whose energies are larger than the average of the remaining energy from the member nodes. After that, by trying to increase the lifetime of the network by equalizing the remaining energy. In to confirm whether improve the lifetime of the network, In this paper, the number of nodes and the position of all nodes are varied for each specific round, the rest energy is equalized, and the algorithm which uniformly selected the cluster head is compared with LEACH.

• Journal of Korea Society of Digital Industry and Information Management
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• v.6 no.1
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• pp.83-90
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• 2010

DTNs (Delay Tolerant Networks) refer to the networks that can support data transmission in the extreme networking situations such as continuous delay and no connectivity between ends. DTMNs (Delay Tolerant Networks) are a specific range of DTNs, and its chief considerations in the process of message delivery in the routing protocol are the transmission delay, improvement of reliability, and reduction of network loading. This article proposes a new LCN (Largest Common Neighbor) routing algorism to improve Spray and Wait routing protocol that prevents the generation of unnecessary packets in a network by letting mobile nodes limit the number of copies of their messages to all nodes to L. Since higher L is distributed to nodes with directivity to the destination node and the maximum number of common neighbor nodes among the mobile nodes based on the directivity information of each node and the maximum number of common neighbor nodes, more efficient node transmission can be realized. In order to verify this proposed algorism, DTN simulator was designed by using ONE simulator. According to the result of this simulation, the suggested algorism can reduce average delay and unnecessary message generation.