• Proceedings of the KIEE Conference
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• 1987.07b
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• pp.1170-1173
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• 1987

A network flow control method, input buffer limit technique which can adjusts the transit traffics in a node, is proposed. The transit traffics that occupy node buffers more threshold are decreased. It has better performance than input buffer limit. The proposed flow control is analyzed by queueing model. Numerical results of some example are shown.

• International Journal of Computer Science & Network Security
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• v.23 no.1
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• pp.153-163
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• 2023

This study is situated in the context of intelligent transport systems, where in-vehicle devices assist drivers to avoid accidents and therefore improve road safety. The vehicles present in a given area form an ad' hoc network of vehicles called vehicular ad' hoc network. In this type of network, the nodes are mobile vehicles and the messages exchanged are messages to warn about obstacles that may hinder the correct driving. Node mobilities make it impossible for inter-node communication to be end-to-end. Recognizing this characteristic has led to delay-tolerant vehicular networks. Embedded devices have small buffers (memory) to hold messages that a node needs to transmit when no other node is within its visibility range for transmission. The performance of a vehicular delay-tolerant network is closely tied to the successful management of the nodes' transit buffer. In this paper, we propose a message transit buffer management model for nodes in vehicular delay tolerant networks. This model consists in setting up, on the one hand, a policy of dropping messages from the buffer when the buffer is full and must receive a new message. This drop policy is based on the concept of intermediate node to destination, queues and priority class of service. It is also based on the properties of the message (size, weight, number of hops, number of replications, remaining time-to-live, etc.). On the other hand, the model defines the policy for selecting the message to be transmitted. The proposed model was evaluated with the ONE opportunistic network simulator based on a 4000m x 4000m area of downtown Bouaké in Côte d'Ivoire. The map data were imported using the Open Street Map tool. The results obtained show that our model improves the delivery ratio of security alert messages, reduces their delivery delay and network overload compared to the existing model. This improvement in communication within a network of vehicles can contribute to the improvement of road safety.

• Journal of Korean Society of Transportation
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• v.21 no.6
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• pp.43-55
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• 2003

This paper presents a new method for estimating potential transit ridership residential population and number of employees that have accesses to transit services. A standard procedure that can be used to determine transit accessibility by pedestrians ad automobiles are developed to improve its transit demand forecasting capability. The analysis results are compared with those from the traditional buffer method as well as the network ratio method. It was found that the proposed method is more accurate than the traditional methods. The new method can be used to better estimate the "Walk Access" transit trips and "Auto Access" transit trips in the Mode Choice Model.

• Journal of the Korean Association of Geographic Information Studies
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• v.11 no.2
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• pp.1-12
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• 2008

This paper identifies public transit-poors and derives spatial characteristics of the poors' distribution in an urban area by utilizing buffering analysis of geographic information systems and remote sensing techniques in the case of Daegu metropolitan city. Since special attention is given to elderlies, this study assigns three hundred meter buffer from bus/subway station as service boundary for elderlies. The results of this study tell us that 1) the transit-poors are concentrated on suburban and rural regions, 2) high proportions of the transit poors are elderlies with spatial variations in many regions, 3) the main housing type of the transit-poors is single detached house. We expect that this study can contribute to build an effective policy-making by showing essential technical processes and methods in identifying policy-need groups and their characteristics of spatial distribution.

• Journal of the Korean Society of Safety
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• v.34 no.2
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• pp.28-33
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• 2019

After the Tianjin Port explosion on 2015, it is highlighted that securing safety for dangerous goods in Korea and try to establish safety standards for railroad dangerous substances transport. In Korea, the regulation for the transport of dangerous goods is stipulated to need 3 buffer cars. However, It is inefficient that 3 buffer cars. because 3 buffer cars, increase transportation too much costs in transit and it is too strict compared to other country rules. The purpose of this study was to improve transportation efficiency by mitigating the criteria for isolated railroads through rational safety assessment. In order to verify this, we used a risk assessment software which is PHAST 7.2 developed by DNV GL. We calculated safety distances that could prevent ignitions setting up scenarios when relief system work installed on a train loaded with propylene, nonane. As a result, we confirmed that buffer cars can be reduced from three to one. This result would be implemented in the application of Korail.

• Journal of the Korean Association of Geographic Information Studies
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• v.16 no.2
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• pp.1-15
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• 2013

It is important to empirically investigate the typological characteristics of subway station areas considering the comprehensive elements of transit-oriented development (TOD) planning so that its implementation can be effective in attaining both increase in transit ridership and decrease in inordinate automobile dependence. This article aims to identify diverse features of subway station areas in Seoul known for good public transit system. After collecting and manipulating the measures on planning elements such as density, diversity and accessibility for TOD planning by distance-based buffer from a subway station, the article tried to interpret analysis results on their typological characteristics. They can be summarized with two conclusions. First, characteristics of landuse and public transit system can be distinctly differentiated in the Seoul subway station areas. It implies that both planning elements should have not been integrated for now. Second, the characteristics of public transit system can be divided by modes. They provide us that public transit system in Seoul needs to be more strongly integrated than current system.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.30B no.1
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• pp.38-44
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• 1993

A model for BICMOS buffer switching operation is presented, including the influence of bipolar base transit time and collector-base capacitances. A closed-form solution for the propagation delay-time is obtained assuming low level injection and channel velocity limitation. For the high level injection case, the delay-times are numerically obtained using effective current gain. These results are compared with those by HSPICE simulation, which shows good agreement. It is noted that the collector-base capacitance strongly affects the delay-time. The effects of voltage scaling are also investigated, which shows the model can be applied for the reduced supply voltages.

• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.10
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• pp.34-42
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• 2012

This paper analyses the energy saving basic power models in core IP networks, and proposes the adaptive buffer and burst scheme which is a possible energy saving method, and its implementation algorithm in core IP networks. Especially this paper describes the adaptive buffer and burst scheme dynamically varying the buffering interval B according to the input traffic volume of ingress router, and explains the operation principle of proposed scheme. This method is to adjust the buffering interval B according to input traffic volume of ingress router, that is increasing the interval B when input traffic volume is low, and decreasing the interval B when input traffic volume is high between some given interval regions. This method can gets the high energy saving effect as decreasing the transition number of idle/active in networks when input traffic volume is low, and decreasing the transition number of idle/active by the continuous of burst packets in transit router when input traffic volume is high. This paper shows the increasing of asleep rate for the energy saving of core IP networks and confirms the energy saving of core IP networks by the computer simulation. We confirmed that proposed method can be save the energy of IP networks by properly trade off network performances.

• Proceedings of the Korea Society for Industrial Systems Conference
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• 1999.12a
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• pp.121-129
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• 1999

When continuous media are transmitted over the communication networks, asynchrony which can not maintain temporal relationships among packets may occur due to a random transit delay. There exist two types of synchronization schemes ; for guaranteed or non-guaranteed resource networks. The former which applies a resource reservation technique maintains delay characteristics, however, the latter supply a best-effort service. In this paper, I propose a intra-media synchronization scheme to transmit continuous media on general networks not guaranteeing a bounded delay tome. The scheme controls transmission times of the packets by estimating next delay time with the delay distribution. So, the arriving packets may be maintained within a limited delay boundary, and playout will be performed after buffering to smoothen small delay variations. The continually increasing delay due to network overload causes buffer underflow at the receiver. To solve it, the transmitter is required to speed up instantaneously. Too much increase of transmission-rate may cause network congestion. At that time, the transmitter drops the current packet when informed excessive delay from the receiver.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.7 s.349
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• pp.93-103
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• 2006

Network solutions for protecting against worm attacks that complement partial end system patch deployment is a pressing problem. In the content-based worm filtering, the challenges focus on the detection accuracy and its performance enhancement problem. We present a worm filter architecture using the bloom filter for deployment at high-speed transit points on the Internet, including firewalls and gateways. Content-based packet filtering at multi-gigabit line rates, in general, is a challenging problem due to the signature explosion problem that curtails performance. We show that for worm malware, in particular, buffer overflow worms which comprise a large segment of recent outbreaks, scalable -- accurate, cut-through, and extensible -- filtering performance is feasible. We demonstrate the efficacy of the design by implementing it on an Intel IXP network processor platform with gigabit interfaces. We benchmark the worm filter network appliance on a suite of current/past worms, showing multi-gigabit line speed filtering prowess with minimal footprint on end-to-end network performance.