• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.7
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• pp.3393-3412
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• 2017

As a main challenge in network virtualization, virtual network embedding problem is increasingly important and heuristic algorithms are of great interest. Aiming at the problems of poor correlation in node embedding and link embedding, long distance between adjacent virtual nodes and imbalance resource consumption of network components during embedding, we herein propose a two-stage virtual network embedding algorithm NA-PVNM. In node embedding stage, resource requirement and breadth first search algorithm are introduced to sort virtual nodes, and a node fitness function is developed to find the best substrate node. In link embedding stage, a path fitness function is developed to find the best path in which available bandwidth, CPU and path length are considered. Simulation results showed that the proposed algorithm could shorten link embedding distance, increase the acceptance ratio and revenue to cost ratio compared to previously reported algorithms. We also analyzed the impact of position constraint and substrate network attribute on algorithm performance, as well as the utilization of the substrate network resources during embedding via simulation. The results showed that, under the constraint of substrate resource distribution and virtual network requests, the critical factor of improving success ratio is to reduce resource consumption during embedding.

• Journal of Korea Multimedia Society
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• v.16 no.9
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• pp.1077-1088
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• 2013

As broadcasting is the process that a node sends a packet to all nodes in the network. it is basic process used for discovering of a routes to a node and disseminating of control information message in Mobile Ad hoc NETwork (MANET). In this paper, we propose dynamically adjusted probabilistic mechanism based on distance ratio and node density for broadcasting in MANETs. The distance ratio can be calculated as the ratio of the radio strength length to the distance from sender of a node, and node density can be get from 1-hop nodes of neighbours. A mobile node receiving broadcast packets determines the probability of rebroadcasting considering distance ratio and node density of itself. Rebroadcast probability will be set as low value to a node which is located in nearby area of sender and has high 1-hop node density, So it reduces packets transmission caused by the early die-out of rebroadcast packets. Compared with the simple flooding and fixed probabilistic flooding by simulation, our approach shows better performances results. Proposed algorithm can reduce the rebroadcast packet delivery more than 30% without scanting reachability, where as it shows up to 96% reachability compared with flooding.

• Proceedings of the IEEK Conference
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• 2000.06a
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• pp.229-231
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• 2000

Nowadays, the telecommunication service provider has witnessed an unprecedented growth in data traffic and the need for networking. optical fiber can provide some THz of huge bandwidth WDM technology has been an emerging issue for the efficient use of optical links. WDM uses a number of different wavelength that are assigned to each channel. The minimal number of optical transceivers and receivers should be used in a node to build an economic WDM transmission system without degrading system performance. Hence, the analysis of performance parameters such as throughput and delay is important to guarantee the WDM system performance. in this paper, the performance of a MAC protocol on a slotted WDM system that has a tunable transmitter(Txt), a tunable receiver(Rxt), and a fixed receiver(Rxf), respectively, on each node, was statistically analyzed The computer simulation validates the performance analysis.

• Journal of Korean Society of Water and Wastewater
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• v.10 no.4
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• pp.85-93
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• 1996

This study is to make a comparison between the node method and the pipeline method for the analysis of the water distribution systems. For these purposes, the two methods were applied to a pipeline system in series, an artificial distribution network and a real distribution network. The results are as follows. 1. The difference between the results of the two methods was increased with the increase of the hydraulic gradient and the length between two adjacent nodes. 2. When all pipe lengths between two adjacent nodes were larger than 200~300m and have the steep hydraulic gradient, it was found that the results of the two methods showed high differences. 3. The difference between the results of the two methods were negligible in the case of the real distribution system in which only 12% whole pipelines were longer than 30m and the longest pipe length was 850m.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.39 no.3
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• pp.232-236
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• 1994

The term underground stem is not used correctly as mesocotyle that is the first internode of barley, wheat and rye. Mesocotyle does not elongate and it remain in the seed in case of these crops. The elongated stem is second internode of these crops and not mesocotyle but rhizome or underground stem. The node on which the underground stem is attached is coleoptile node and coleptile is attached here. The objective of this study was to determine if the depth of sowing affect the coleoptile length and plant height. The deeper sowing caused the longer coleoptile length and plant height. Coleoptile length and plant height of 2cm depth of sowing showed significant difference with 6cm and 10cm depth of sowing in barley and wheat. Variation of these two characters were high in rye and corn because these crops were both heterogeneous due to out crossing. All the varieties of 4 crops showed significant correlation between coleoptile length and plant height. Chilbohomil showed highly significant correlation between two characters.

• Journal of Bio-Environment Control
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• v.29 no.4
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• pp.406-413
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• 2020

This study was conducted to find out optimum fruiting node order, pinching node order, and harvesting time in hydroponics using coir substrates to produce high quality melon (Cucumis melo L.) fruit. Three plants per coir slab (100 × 20 × 10 cm) were planted for each treatment. Yamazaki standard nutrient solutions for melon were supplied with 1.8, 2.0, and 2.3 dS·m^-1 at the early, middle (fruit enlargement step), and late growth stages, respectively. Two cultivars of 'PMR Dalgona' and 'Earl's Aibi' were used for fruiting node order and pinching node order experiments. Fruiting node treatments were conducted three replications (8-10 ^th, 11-13 ^th, and 14-15 ^th nodes) and pinching node treatments treated with three replications (18 ^th, 21 ^th, and 24 ^th nodes). Two cultivars of 'PMR Dalgona' and 'Earl's Crown' were used for fruit harvesting time experiment and treated with in four replications (45, 50, 55, and 60 days after fruiting). In growth characteristics, the leaf width and leaf area of 'PMR Dalgona' were the greatest 28.2 cm and 10,845 ㎠. Respectively, 11-13 ^th fruiting nodes or more. The node length of 'Earl's Aibi' was the longest by 147.6 cm at 11-13 ^th fruiting nodes. For fruit quality characteristics, the fruit weight of 'Earl's Aibi' at 11-13 ^th fruiting node fruiting was the greatest by 2.0 kg. The soluble solids content (SSC) of 'PMR Dalgona' was the highest by 14.5 °Brix at 8-10 ^th nodes in fruiting node orders and 14.5 °Brix at the 24 ^th pinching node order, respectively with significant difference. The SSC tends to increase in the same for both cultivars of 'PMR Dalgona' and 'Earl's Aibi' as the position of fruiting node was lower. The SSC and fruit weight of melon harvested at 55-60 days after fruiting was the best. From the results of this study, most of SSC tends to increase in the lower position of fruiting node order and the higher pinching node order, whereas the fruit weight shows a tendency of increasing with higher fruiting node. In addition, the SSC of fruit increased as the number of days after fruiting increased, and further research is needed for more various cultivars. In melon hydroponics using coir substrates, it is needed to figure out the characteristics of each cultivar to determine optimum fruiting node order, pinching node order, and fruit harvest time.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.2
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• pp.447-450
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• 2012

Video-assisted thoracic surgery (VATS) has been recommended as more optimal surgical technique than traditional thoracotomy for lobectomy in lung cancer, but it is not well defined. Here, we compared VATS and traditional thoracotomy based on clinical data. From November 2008 to November 2010, 180 patients underwent lobectomy for non-small-cell lung cancer (NSCL) identified by computerized tomography. Of them, 83 cases were performed with VATS and 97 by thoracotomy. Clinical parameters, consisting of blood loss, operating time, number of lymph node dissection, days of pleural cavity drainage, and length of stay were recorded and evaluated with t test. No significant difference was observed between the VATS and thoracotomy groups in the average intraoperative blood loss, number of lymph node dissections, and days of pleural cavity drainage. While the average operating time in the VATS group was significantly longer than that in thoracotomy group, recurrence was only present in one case, as opposed to 7 cases in the thoracotomy group In conclusion, similar therapeutic effects were demonstrated in VATS and thoracotomy for NSCL. However, VATS lobectomy was associated with fewer complications, recurrence and shorter length of stay.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.18 no.1
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• pp.35-38
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• 1982

Ship hull Vibration is caused by troubling measure instruments installed in the ship, fatigue of the hull girder. Vibration has been studied by the View point of anti-Vibration. However, the theoretical calculation values of the Vibration analysis were not obtained accurately. Therfore, in this paper, Vibration analysis were made on the two (cylinder form, ship form) of ship hull girder by the transfer matrix method. The super-structure length was determined to be 0, 20, 40, 60, 80, 100, percentage of the ship's length from the stern. The results of analysis by the transfer matrix method are as follow. 1. Natural frequency may be determined by the order of node numbers and superstructure length. 2. Natural frequency inereased when the ship form is a finess and increasing ratio followed by high order of node numbers.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.12
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• pp.4856-4871
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• 2015

Backpressure based scheduling has been considered as a promising technique for improving the throughput of a wide range of communication networks. However, this scheduling technique has not been well studied for heterogeneous wireless networks. In this paper, we propose a virtual-queue based backpressure scheduling (VQB) algorithm for heterogeneous multi-hop wireless networks. The VQB algorithm introduces a simple virtual queue for each flow at a node for backpressure scheduling, whose length depends on the cache size of the node. When calculating flow weights and making scheduling decisions, the length of a virtual queue is used instead of the length of a real queue. We theoretically prove that VQB is throughput-optimal. Simulation results show that the VQB algorithm significantly outperforms a classical backpressure scheduling algorithm in heterogeneous multi-hop wireless networks in terms of the packet delivery ratio, packet delivery time, and average sum of the queue lengths of all nodes per timeslot.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.2
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• pp.257-262
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• 2001

A new WDM-based protocol for scheduling a variable-length message is proposed in this paper Two control channels, reservation slot and control slot, are used to coordinate transmission and diminish the collisions of packet to minimize the across delay. When an idle control slot is available, control packet is transmitted on that slot and message is transferred. And the node continues to transmit its control packet through the corresponding slot every cycle, until the message is completely transmitted. If any control slot is not available, the node schedules the transmission time of message in earliest available time using reservation slots. The proposed scheduling algorithm shows better performance and lower access delay.