• Proceedings of the Korean Operations and Management Science Society Conference
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• 2007.11a
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• pp.325-329
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• 2007

The mobile and multimedia service on wireless network have been leaded from the improvement of telecommunication techniques. A typical multimedia service, a video transmission usually requires larger bandwidth than voice transmission. Many channel allocation algorithms for Orthogonal Frequency Division Multiple Access (OFBMA) to use resources more efficiently, Previous channel allocation algorithms have developed with an assumption that the data traffic is constant bit rate (CBR). However, existing algorithms are not suitable to video traffic because it usually generates a variable bit rate (VBR) traffic. In this paper, we proposed a new channel allocation algorithm called a queue-based channel allocation. it is more suitable to transmit the video traffics. Also, a problem are notified in case of realtime generated video traffic and a corresponding heuristic solution was proposed.

• Journal of Internet Computing and Services
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• v.3 no.6
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• pp.35-41
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• 2002

The Car Navigation System(CNS) requires lots of memory and calculating time because it works on the large and complex digital map. And the traffic circumstances vary time by time, so the traffic informations should be processed if we want to get mere realistic result. This paper proposes an effective path searching algorithm which uses less memories and calculating time by applying directional information between the starting place and destination place and by using realtime traffic informations.

• The KIPS Transactions:PartC
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• v.8C no.5
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• pp.517-524
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• 2001

There are cases that revoke the certification because of disclosure of private key, deprivation of qualification and the expiration of a term of validity based on PKI. So, a user have to confirm the public key whether valid or invalid in the certification. There are many method such as CRL, Delta-CRL, OCSP for the cert-validation of certification. But these method many problems which are overload traffic on network and the CRL server because of processing for cert-validation of certification. In this paper we proposed the realtime cert-validation of certification method which solved problems that are data integrity by different time between transmission and receiving for CRL, and overload traffic on network and the CRL server based on DARC.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.4B
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• pp.349-354
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• 2006

In 3G networks interworking with external IP-based networks, provision of end-to-end QoS to packet-based services is a critical issue. In this paper, we propose DiffServ-aware Multiple Protocol Label Switching(MPLS) as a new policy enforcement means. With the adoption of the proposed DiffServ-aware MPLS, it is feasible to provide differentiated QoS provision with the help of DiffServ as well as to improve network utilization by using multiple paths based on MPLS. We verify the effectiveness of our proposed policy enforcement means through a simulation in which realtime traffic and non-realtime traffic are served together.

• The Transactions of the Korea Information Processing Society
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• v.4 no.5
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• pp.1308-1318
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• 1997

This paper proposes a new touthind algorithm, the Bandwidth-Delay-Loss based Routing(BDLR) algotithm, which supports the selection of an effcienet routing path by cinsidering the characteristics and QoS requirements of intergarted servies over the Untegrated Serives Packet Network(ISPN), and also compareas it with other touting algorithms by simulating their perfomances on the various combinations of the realtime and non-realtime traffic over the ISPN. The simulation shows that the BDLR algorithm takes great advantages on transmisson dealy, the satisfiability of QoS requirements, and the adapation of traffic envirment over the other routing algorithms priposed for ISPN until now.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.12 no.3
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• pp.3-13
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• 2002

There are cases that revoke the certification because of disclosure of private key, deprivation of qualification and the expiration of a term of validity on PKI. So, a user has to confirm the public key whether valid or invalid in the certification. There are many methods such as CRL, Delta-CRL, OCSP for the cert-validation of certification. But these methods have many problems, which cause overload traffic on network and the CRL server because of realtime processing for cert-validation of certification. In this paper we proposed cert-validation of certification improvement method based on FM Subcarrier Broadcasting, which solved problems that are data integrity by different time between transmission and receiving for CRL, and overload traffic on network and the CRL server the realtime management.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.8 no.3
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• pp.35-45
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• 2008

Realtime visibility measurement using camera is a new method which can collect some realtime visibility data similar to those of the human eyes, and can replace the existing methods using the expensive optical equipment. There have been a few attempts to measure visibility by extracting depth and three-dimensional structure under bad weather conditions. However, if there are many movements of objects in the image, these approaches seem to be inappropriate. In addition, the realtime visibility measurement will require a relatively simple and fast processing. Typically the contrast degrades exponentially in the bad weather. Therefore, in this paper we propose an easy and quick method that extract contrast from images using a moving area filter and measure visibility by mathematically modelling of the relationship between image contrast and visibility. The moving area filter is used for removing the area of the sky and moving objects that affect visibility measurement on images. The method proposed here can make possible not only realtime visibility measurement from images taken by CCD cameras, but also steady visibility measurement by using the moving area filter in case of much traffic on the road.

• Journal of Communications and Networks
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• v.9 no.4
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• pp.511-523
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• 2007

In broadband convergence network(BcN), heterogeneous broadband wired & wireless subnetworks and various terminal equipments will be interconnected. In order to provide end-to-end realtime multimedia services on such heterogeneous networking environment, as a result, two major problems should be resolved: i) Multimedia session establishment & negotiation that adjusts the differences in the capability of multimedia data processing at the end terminal nodes, ii) quality of service(QoS)-guaranteed connection establishment or resource reservation with connection admission control(CAC) in each heterogeneous subnetworks along the path. The session layer signaling(e.g., SIP/SDP) should be extended for QoS negotiation, and must be tightly cooperating with network layer signaling or resource reservation with CAC function. In this paper we propose a session and connection management architecture for the QoS-guaranteed realtime multimedia service provisioning on BcN, with Q-SIP/SDP, resource reservation protocol with traffic engineering extension, and CAC functions. The detailed interaction scenario and related algorithms for QoS-guaranteed realtime multimedia session, resource reservation and connection establishment are explained and analyzed. From the experimental implementation of the proposed scheme on a small scale BcN testbed, we verified that the proposed architecture is applicable for the realtime multimedia service provisioning. We analyze the network performance and QoS parameters in detail.

• Journal of the Korean Institute of Intelligent Systems
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• v.23 no.3
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• pp.220-225
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• 2013

Accidents between ships occur frequently at the traffic congestion area. Once a maritime accidents occur, it is likely to end up with critical damaged accidents. This paper develop a simulator for assessing quantitative risk based on statical maritime traffic data and realtime traffic distribution. Ship's passage risk assessment simulator consist of import of division of passage data, traffic distribution analysis and passage risk assessment analysis. Maritime traffic data of WANDO waterway apply to simulator for calculation of quantitative risk rate of waterway.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.4
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• pp.286-295
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• 2007

This paper presents an intelligent PID control for stochastic systems with nonstationary nature. We optimally determine parameters of a PID controller through learning algorithm and propose an online PID control to compensate system errors possibly occurred in realtime implementations. A dynamic Bayesian network (DBN) model for system errors is additionally explored for making decision about whether an online control is carried out or not in practice. We apply our control approach to traffic control of Transmission Control Protocol (TCP) networks and demonstrate its superior performance comparing to a fixed PID from computer simulations.