• The KIPS Transactions:PartC
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• v.14C no.5
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• pp.425-430
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• 2007

Without the aid of stationary infrastructure, maintaining routing information for all nodes is inefficient in the Mobile Ad hoc Networks(MANET). It is more efficient when every time routing information is necessary that the source node broadcasts a query message to neighbour nodes. The source node using Ad hoc On-Demand distance Vector(AODV), which is one of the routing protocols of MANET, uses the Expanding Ring Search(ERS) algorithm which finds a destination node efficiently. In order to reduce the congestion of the network, ERS algorithm does not broadcast Route REQuest(RREQ) messages in the whole network. When the timer expires, if source node does not receive Route REPly(RREP) messages from the destination node, it gradually increases TTL value and broadcasts RREQ messages. Existing AODV cost a great deal to find a destination node because it uses a fixed NODE_TRAVERSAL_TIME value. Without the message which is added in existing AODV protocols, this paper measures delay time among the neighbours' nodes by making use of HELLO messages. We propose Adaptive ERS(AERS) algorithm that makes NET_TRAVERSAL_TIME optimum which apply to the measured delay time to NODE_TRAVERSAL_TIME. AERS suppresses the unnecessary messages, making NET_TRAVERSAL_TIME optimum in this paper. So we will be able to improve a network performance. We prove the effectiveness of the proposed method through simulation.

• The KIPS Transactions:PartA
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• v.12A no.6 s.96
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• pp.557-562
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• 2005

Throughput and latency of interconnection network are important factors of the performance of multiprocessor systems. The dual-link CC-NUMA architecture using point-to-point unidirectional link is one of the popular structures in high-end commercial systems. In terms of optimal path between nodes, several paths exist with the optimal hop count by its native multi-path structure. Furthermore, transaction latency between nodes is affected by congestion of links on the transaction path. Hence the transaction latency may get worse if the transactions make a hot spot on some links. In this paper, I propose a dynamic transaction routing algorithm that maintains the balanced link utilization with the optimal path length, and I compare the performance with the fixed path method on the dual-link CC-NUMA systems. By the proposed method, the link competition is alleviated by the real-time path selection, and consequently, dynamic transaction algorithm shows a better performance. The program-driven simulation results show $1{\~}10\%$ improved fluctuation of link utilization, $1{\~}3\%$ enhanced acquirement of link, and $1{\~}6\%$ improved system performance.

• The KIPS Transactions:PartC
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• v.13C no.7 s.110
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• pp.889-896
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• 2006

ATM Forum has defined a guaranteed frame rate (GFR) service to serve Internet traffic efficiently. The GFR service provides virtual connections (VCs) for minimum cell rate (MCR) guarantees and allows them to fairly share the residual bandwidth. And ATM Forum has recommended a frame-based generic cell rate algorithm (F-GCRA) as a frame classifier, which determines whether an Am cell is eligible to use the guaranteed bandwidth in a frame level. An ATM switch accommodates cells in its buffer or drops them in a frame level according to current buffer occupancy. A FIFO shared buffer has so simple structure as to be feasibly implemented in switches, but has not been able to provide an MCR guarantee for each VC without buffer management based on per-VC accounting. In this paper, we enhance the F-GCRA frame classifier to guarantee an MCR of each VC without buffer management based on per-VC accounting. The enhanced frame classifier considers burstness of TCP traffic caused by congestion control algorithm so as to enable each VC to use its reserved bandwidth sufficiently. In addition, it is able to alleviate the unfairness problem in usage of the residual bandwidth. Simulation results show that the enhanced frame classifier satisfies quality of services (QoSs) of the GFR service for the TCP traffic.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2005.10a
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• pp.111-116
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• 2005

The approaching waters of Po-hang port will be increased the traffic volume and passage of larger vessel according to the opening of Young-il new port in 2006. But the adjacent area of Po-hang port still exist the danger elements of safe navigation, the disordered navigation and traffic congestion. Therefore the safety of traffic must be improved in Po-hang vicinity area. This paper describes the status of marine traffic flow and navigational characteristics based on the marine traffic survey using the exclusive software, and the results of marine traffic survey classify into the ship's types and tonnage and track history of passing ships through the statistical method. Finally the examinations of main traffic route, traffic flow and navigational characteristics are discussed, and these results can be utilized the best design of ship's routing at the Po-hang approaching water.

• Journal of Intelligence and Information Systems
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• v.20 no.1
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• pp.121-131
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• 2014

Traffic speed is an important measure in transportation. It can be employed for various purposes, including traffic congestion detection, travel time estimation, and road design. Consequently, accurate speed prediction is essential in the development of intelligent transportation systems. In this paper, we present an analysis and speed prediction of a certain road section in Busan, South Korea. In previous works, only historical data of the target link are used for prediction. Here, we extract features from real traffic data by considering the neighboring links. After obtaining the candidate features, linear regression, model tree, and k-nearest neighbor (k-NN) are employed for both feature selection and speed prediction. The experiment results show that k-NN outperforms model tree and linear regression for the given dataset. Compared to the other predictors, k-NN significantly reduces the error measures that we use, including mean absolute percentage error (MAPE) and root mean square error (RMSE).

• The Korean Journal of Physiology
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• v.2 no.2
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• pp.63-73
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• 1968

It is well known that mammalian alveolar membrane is covered with a very thin layer of surfactant film which characteristically reduces surface tension of alveolar membrane, and maintains alveolar stability. Since Clements in 1957 demonstrated that the surfactant is extractable by mincing the lung tissue in saline, various studies on the subject have been succeeded by many workers. However, the effect of radiation on the surfactant is not well clarified. Present study was attempted to observe the effect of x-irradiation on the activity of surfactant in rabbits. X-ray in dose of 300 r, 600 r or 900 r was irradiated to the chest of rabbits. The lung was removed from normal or irradiated rabbits sacrificed by arterial blood shedding, and lung-saline extract, adding 3 grams of lung tissue to 50 mili-liters of saline, was prepared by means of Vertis homogenizer. Tension-area diagram of lung extract was recorded automatically by a modified Langmuir-Wilhelmy balance with a synchronized recording system designed in this department. The surface tension of lung extract was measured at 1st, 2 nd, 3 rd, 7 th and 15 th post-radiation day in 300 r irradiated group, at 3 rd, 7 th and 15 th post-radiation day in 600 r irradiated group, 3 rd and 7 th post-radiation day in 900 r irradiated group respectively. For the histo-pathological study, lung tissue preparations were made in all irradiatiated groups on the day of experiment and in normal group. The results obtained are summarized as follows: 1. The minimal surface tension, maximal surface tension and stability index of normal rabbits lung extracts were 7.68 dynes/cm, 38.84 dynes/cm, and 1.39 respectively. 2. The activity of surfactant was depressed prominently by x-irradiation. However, increase in the dose of x-irradiation did not show any significant change in the degree of surfactant activity suppression. The most marked depression in surfactant was observed at the third post-radiation day in all irradiated groups. 3. Activity of surfactant depressed by x-irradiation showed a tendency of recovering to normal on 15 th post-radiation day. 4. The tendency of change in activity of surfactant following x-irradiation was somewhat correlative with histo-pathological changes. But the degree of depression of surfactant by x-irradiation did not correspond to the degree of histo-pathological changes, and recovery of lung tissue from radiation damage, tissue edema and congestion, seemed to be followed by restoration of surfactant activity. 5. The width of the tension-area diagram was measured at the surface area of 40% in lung extract of normal and x-irradiated rabbits. And it was found that the changes of the width corresponded well with that of minimum surface tension and of stability index in all normal and x-irradiated groups.

• The Korean Journal of Pain
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• v.20 no.1
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• pp.15-20
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• 2007

Background: Lipo-prostaglandin E1 (Lipo-$PGE_1$) has vasodilating and platelet aggregation inhibitory characteristics and it has been used as a treatment for patients with blood flow dysfunction disease. Based on the mechanisms of lumbar spinal stenosis, including veno congestion, neuro-ischemia and mechanical compression, we aimed to study whether intravenous Lipo-$PGE_1$ injection has any therapeutic effect on hyperalgesia in a rat foraminal stenosis model. Methods: In this study, twenty male Sprague-Dawley rats were divided into the control (n = 10) and Lipo-$PGE_1$ (n = 10) groups. A small stainless steel rod was inserted into the L5-6 intervertebral foramen to induce intervertebral foramen stenosis and chronic DRG compression. In the Lipo-$PGE_1$ group, $0.15{\mu}g/kg$ of Lipo-$PGE_1$ were injected intravenously via a tail vein for 10 days starting from the $3^{rd}$ day after operation. Behavioral testing for mechanical and thermal hyperalgesia was performed for 3 weeks after the injections. Results: From the $10^{th}$ day after Lipo-$PGE_1$ injection, the rats in the experimental group showed significant recovery of their mechanical threshold, and this effect was maintained for 3 weeks. No significant differences of the thermal hyperalgesia were observed between the two groups. Conclusions: These findings suggest that intravenously injected Lipo-$PGE_1$ may be effective for alleviating neuropathic pain, which isthe main symptom of spinal stenosis, by improving the blood flow dysfunction.

• Journal of the Society of Disaster Information
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• v.15 no.4
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• pp.548-559
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• 2019

Purpose: Analysis method of V2I data driven motorway service area usage behavior to cope with manpower survey. Method: Segmentation of traveling state group and boundary using the distribution characteristics of traveling speed data of individual vehicles. Result: As a result of the verification, the use rate of resting places in lunchtime surged, and the boundary between the distribution status of the traffic speed data was clearly or unclear. Conclusion: The effect of the cost reduction is big because it can cope with the use of rest area survey by manpower and there is no limit in the time and space range of investigation. The dynamic utilization rate of each time sequence, such as a service area/drowsiness shelter/simple service area, with a V2I system, can be calculated. Identify illegal parking on highway section. Identify the unexpected situation in the road section. Identify the real-time service area utilization rate and congestion information.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.12
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• pp.5622-5632
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• 2011

This paper presents the simulation design and analysis of Integrated Logistics System(ILS) which is operated by using the AGV(Automated Guided Vehicle). To maximize the operation performances of ILS with AGV, many parameters should be considered such as the number, velocity, and dispatching rule of AGV, part types, scheduling, and buffer sizes. We established the design of experiment in a way of Orthogonal Array in order to consider (1)maximizing the throughput; (2)maximizing the vehicle utilization; (3)minimizing the congestion; and (4)maximizing the Automated Storage and Retrieval System(AS/RS) utilization among various critical factors. Furthermore, we performed the optimization by using the simulation-based analysis and Evolution Strategy(ES). As a result, Orthogonal Array which is conducted far fewer than ES significantly saved not only the time but the same outcome when compared after validation test on the result from the two methods. Therefore, this approach ensures the confidence and provides better process for quick analysis by specifying exact experiment outcome even though it provides small number of experiment.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.5
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• pp.3071-3080
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• 2015

The increased demand on the transport of both passengers and goods through rail systems implies higher traffic intensity and congestion on the railways, resulting in greater likelihood of accidents and also degraded passenger services. To cope with the issues, development of an integrated communication network for rails has attracted great deal of attention lately. GSM-R is such an example developed in Europe, which seems to have restrictions in providing various communication services due to network speed limit. For the reason, an LTE-based approach is under study in Korea. After the network development, operation management of the network is necessary. Design of operation management systems has been studied little and thus is the objective of this paper. To do so, a conceptual design has been carried out based on model-based approach. Specifically, a context model has first been created using the use case diagram. Then, SysML models of operational scenarios were developed for the management system. The SysML models have alternatively been expressed as EFFBD models to simulate and verify them. Consequently, the result of the conceptual system design for the operation management of the integrated wireless network is expected to be used as a basis for the detailed design later.