• Journal of the Korean GEO-environmental Society
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• v.22 no.12
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• pp.71-77
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• 2021

As the number of using road in Korea increases, maintenance costs and traffic congestion costs also increase. In order to reduce maintenance cost and time of road, existing long - lived modular road system has been proposed. In this study, the design and performance evaluation of the adaptable support module, which is the substructure of the proposed system, was performed. Two adaptable (Cross-Beam type)support modules were designed and fabricated to determine the load and shape. A adaptable support module was constructed and a static load test was carried out to select the type with better performance. As a result of the load test, the maximum value of the measured earth pressure difference is about 158 kPa and the settlement amount is about 0.032 mm in the two types of adaptable support modules. Based on these results, it is concluded that the performance of the adaptable support module of the bottom curved cross-beam type is better.

• The Journal of the Korea institute of electronic communication sciences
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• v.18 no.6
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• pp.1081-1086
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• 2023

The rapid growth and increasing complexity of modern networks have highlighted the limitations of traditional network architectures. The emergence of SDN (Software-Defined Network) in response to these challenges has changed the existing network environment. The SDN separates the control unit and the data unit, and adjusts the network operation using a centralized controller. However, this structure has also recently caused a huge amount of traffic due to the rapid spread of numerous Internet of Things (IoT) devices, which has not only slowed the transmission speed of the network but also made it difficult to ensure quality of service (QoS). Therefore, this paper proposes a method of load distribution by switching the IP and any server (processor) from the existing data processing scheduling technique, RR (Round-Robin), to mapping when a large amount of data flows in from a specific IP, that is, server overload and data loss.

• Journal of the Korean Geotechnical Society
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• v.33 no.8
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• pp.5-16
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• 2017

When a lateral load is applied to a short pile whose embedded depth is relatively smaller than its diameter, an overturning failure occurs. To investigate the behavior of laterally loaded short piles, several model tests in laboratory scales had been carried out, however the behavior of large moment carrying piles for electric poles, traffic sign and road lamp, etc. have not been revealed yet. This paper deals with the real-scale load tests for 750 mm diameter short piles. To simulate the actual loading condition, very large moment was mobilized by applying lateral loads to the location 8 m away from the pile head. Three load tests changing the pile embedded lengths to 2.0 m, 2.5 m, and 3.0 m were carried out. The test piles overturned abruptly with very small displacement and rotation before the failures. These brittle failures are in contrast with the ductile failures shown in the former model tests with the relatively smaller moment to lateral load ratio. Comparisons of the test results with three existing methods for the estimation of the ultimate lateral capacity show that the method assuming the rotation point at pile tip matches well when the embedded depth is small, however, as the embedded depth increases the other two methods assuming the inversion of soil pressure with respect to rotation points in pile length match better.

• The KIPS Transactions:PartC
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• v.16C no.6
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• pp.773-782
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• 2009

A DHT(Distributed Hash Table) based P2P is a method to overcome disadvantages of the existing unstructured P2P method. If a DHT algorithm is used, it can do a fast data search and maintain search efficiency independent of the number of peer. The peers in the DHT method send messages periodically to keep the routing table updated. In a mobile environment, the peers in the DHT method should send messages more frequently to keep the routing table updated and reduce the failure of a request. Therefore, this results in increase of network traffic. In our previous research, we proposed a method to reduce the update load of the routing table in the existing Chord by updating it in a reactive way, but the reactive method had a disadvantage to generate more traffic than the existing Chord if the number of requests per second becomes large. In this paper, we propose an adaptive method of routing table update to reduce the network traffic. In the proposed method, we apply different routing table update method according to the number of request message per second. If the number of request message per second is smaller than some threshold, we apply the reactive method. Otherwsie, we apply the existing Chord method. We perform experiments using Chord simulator (I3) made by UC Berkeley. The experimental results show the performance improvement of the proposed method compared to the existing methods.

• The KIPS Transactions:PartC
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• v.16C no.6
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• pp.761-772
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• 2009

A DHT(Distributed Hash Table) based P2P is a method to overcome disadvantages of the existing unstructured P2P method. If a DHT algorithm is used, it can do a fast data search and maintain search efficiency independent of the number of peer. The peers in the DHT method send messages periodically to keep the routing table updated. In a mobile environment, the peers in the DHT method should send messages more frequently to keep the routing table updated and reduce the failure of a request. Therefore, this results in increase of network traffic. In our previous research, we proposed a method to reduce the update load of the routing table in the existing Chord by updating it in a reactive way, but the reactive method had a disadvantage to generate more traffic than the existing Chord if the number of requests per second becomes large. In this paper, we propose an adaptive method of routing table update to reduce the network traffic. In the proposed method, we apply different routing table update method according to the number of request message per second. If the number of request message per second is smaller than some threshold, we apply the reactive method. Otherwsie, we apply the existing Chord method. We perform experiments using Chord simulator (I3) made by UC Berkeley. The experimental results show the performance improvement of the proposed method compared to the existing methods.

• The Transactions of the Korea Information Processing Society
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• v.3 no.4
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• pp.697-708
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• 1996

In this paper, we study reactive congestion control with priority in ATM network. The priority schemes for buffer access, partial buffer sharing have been investigated in order to improve the utilization of ATM network resources the network and to satisfy the most demanding traffic class. We consider in this paper a discrete-time queueing model for partial buffer sharing with two Markov modulated Poisson inputs. This model can be used to analyze the the effects of the partial buffer sharing priority scheme on system performance for realistic cases of bursty services. Explicit formulae are derived for the number of cells in the system and the loss probabilities for the traffic. Congestion may still occur because of unpredictable statistical fluctuation of traffic sources even when preventive control is performed in the network. In this Paper, we study reactive congestion control, in which each source changes its cell emitting rate a daptively to the traffic load at the switching node. Our intention is that,by incorporating such a congcstion control method in ATM network,more efficient congsestion control is established. We develope an analytical model,and carry out an approximateanalysis of reactive congestion con-trol with priority.Numerical results show that several orders of magnitude improvement in the loss probability can be achieved for the high priority class with little impact on the low priority class performance.And the results show that the reactive congestion control with priority are very effective in avoiding congestion and in achieving the statistical gain.

• International Journal of Highway Engineering
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• v.10 no.3
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• pp.109-118
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• 2008

This study analyzes the change of stability of embankment due to the construction of embankment combined used road with two different construction phases. The stabilities have been checked both in the phase of earth banking for a road construction and in the phase of the application of the traffic roads(DB-24). In both cases the factor of safety has been found higher than 1.3 which is the general criterion of the safety of an embankment. The results indicate that the safety of an embankment due to the construction of embankment combined use road is assured, and thus, it is thought that the construction of embankment combined use road can be considered for cutting down on expenses of construction sites for a road construction. However, the pre-examination of stability due to the construction should be carried out because it decreases the factor of safety of an embankment. From this study, it has been found that the factor of safety was dropped most when the water level rose in the transient flow. The result indicates that the stability analysis of a river embankment where the water level changes frequently should be carried out in the condition of transient flow. It is recommended that the inner side of an embankment should have a slope of 1:2 which is identical with the slope of the existing embankment. In addition, the factor of safety also can be decreased due to the traffic loads, and therefore, the effect should also be considered after the construction of embankment combined used road limiting the traffic loads.

• Journal of Power Electronics
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• v.6 no.4
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• pp.322-329
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• 2006

In the last decade, the increasing restrictions imposed on the exhaust emissions from internal combustion engines and traffic limitations have increased the development of electrical propulsion systems for automotive applications. The goal of electrical and hybrid vehicles is the reduction of global emissions, which in turn leads to a decrease in fuel resource exploitation. This paper presents a novel approach for control of Induction Motors (IM) using the Particle Swarm Optimization (PSO) algorithm to optimize the parameters of the Proportional Integral Controller (PI-Controller). The overall system is simulated under various operating conditions. The use of PSO as an optimization algorithm makes the drive robust and insensitive to load variation with faster dynamic response and higher accuracy. The system is tested under variable operating conditions. The simulation results show a positive dynamic response with fast recovery time.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.420-427
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• 2011

It is most important to support the track as well as to be directly connected to run safety. The performance design satisfied with the more safe and economic embankment study is required due to the high speed, design load and growth of traffic. Therefore, in this paper the relation between main design elements to adopt the method of the performance design were analysed. And the correlation among design indices developed and used in an advanced countries such as germany, japan were evaluated.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.1555-1561
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• 2011

The dynamic behavior of a bridge under moving loads has been investigated over many years. Especially, with the introduction of High Speed Railway, numerous theoretical studies on the interaction problem between bridges and trains are carried out. In the present study, advanced bridge/train interaction analyses are performed and compared with field tests of a simply-supported 40m long PSC box girder bridge of Kyung-Bu High Speed Railway. Vertical displacements and vertical accelerations of a bridge with increasing speeds are analyzed. In addition, wheel load reduction rates and accelerations of a car-body of the train are investigated for a study of appropriateness of traffic safety criteria of bridge design specification.