• Journal of Information Processing Systems
• /
• v.2 no.3 s.4
• /
• pp.170-177
• /
• 2006

Recently, RFID technology has attracted considerable attention in many industry fields. The RFID environment requires a standard architecture for the smooth exchange of data between heterogeneous networks. The architecture should offer an efficient standard environment, such as a communication environment based on Web Services, PKI or Kerberos-based security, and abstract business processes which could be used in the diverse domains. Therefore, in this paper, we propose an Enterprise Application Framework (EAF) which includes a standard communication protocol, security functions, and abstract level business processes. The suggested architecture is expected to provide a more secure and flexible security management in the dynamic RFID application environments, and is expected to provide an abstract business event for the development of business processes which could apply RFID technology to the existing systems.

• Journal of the Korean Professional Engineers Association
• /
• v.16 no.1
• /
• pp.4-12
• /
• 1983

Data communication has historically evolved from leased lines, to use of the public telephone network, and eventually to dedicated(exclusive) data networks. It requires an enormous amount of money for establishing a separate and independent data network at the beginning stage. No country has ever adopted this method In the Republic of Korea too the age of leased circuits is passing and it is scheduled to open the public telephone network to the data transmission and to install packet mode processor in the last half of 1983. This paper presents a survey on characteristics of the public telephone network in Seoul and a future development of the data communication of Korea.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.9 no.7
• /
• pp.2338-2353
• /
• 2015

In this paper, the optimal power allocation algorithm that minimizes the aggregate bit error rate (BER) of the secondary user (SU) in a downlink orthogonal frequency division multiplexing (OFDM) based cognitive radio (CR) system, while subjecting to the interference power constraint and the transmit power constraint, is investigated under the assumption that the instantaneous channel state information (CSI) of the interference links between the secondary transmitter and the primary receiver, and between the primary transmitter and the secondary receiver is perfectly known. Besides, a suboptimal algorithm with less complexity is also proposed. In order to deal with more practical situations, we further assume that only the channel distribution information (CDI) of the interference links is available and propose heuristic power allocation algorithms based on bisection search method to minimize the aggregate BER under the interference outage constraint and the transmit power constraint. Simulation results are presented to verify the effectiveness of the proposed algorithms.

• Journal of the Korean Operations Research and Management Science Society
• /
• v.18 no.1
• /
• pp.45-54
• /
• 1993

Monitoring processor in a circuit switched network is considered. Monitoring processor monitors communication links offers a grade of service in each link to controller. Such an information is useful for an effective maintenance of system. Two links with asymmetric system parameters and multi-symmetric links are respectively considered. Each links is to be an independent M /M/ 1/ 1/ type. Markov modeling technique is used to represent a model of monitoring processor with FCFS steering protocol. Performance measures considered are ratio of monitored jobs in each link, availability of minitoring processor and throughput of virtual processor in each link. The value of the performance meausres are compared with existing and simulation results.

• Journal of information and communication convergence engineering
• /
• v.18 no.2
• /
• pp.100-105
• /
• 2020

With the advent of the 5G era, the rapid growth in demand for mobile content services has increased the need for additional backhaul investment. To meet this demand, employing a content delivery network (CDN) and optical access solution near the last mile has become essential for the configuration of 5G networks. In this paper, a cache-enabled architecture using the passive optical network (PON) is presented to serve video on demand (VoD) for users. For efficient use of mobile backhaul, I propose a request deduplication scheme (RDS) that can provide all the requested services missed in cache with minimum bandwidth by eliminating duplicate requests for movies within tolerable range of the quality of service (QoS). The performance of the proposed architecture is compared with and without RDS in terms of the number of requests arriving at the origin server (OS), hit ratio, and improvement ratio according to user requests and cache sizes.

• Journal of Communications and Networks
• /
• v.5 no.2
• /
• pp.167-173
• /
• 2003

We treat the problem of channel estimation and interference cancellation in multiuser ultra-wide-band (UWB) communication systems over multipath fading channels. The UWB system under consideration employs a random time-hopping impulse radio format. We develop a channel estimation method based on linear weighted algorithm. An iterative channel estimation and interference cancellation scheme is proposed to successively improve the receiver performance. We also consider systems employing multiple transmit and/or receive antennas. For systems with multiple receive antennas, we develop a diversity receiver for the wellseparated antennas. For systems with multiple transmit antennas, we propose to make use of Alamouti’s space-time transmission scheme, and develop the corresponding channel estimation and interference cancellation receiver techniques. Simulation results are provided to demonstrate the performance of various UWB receiver techniques developed in this paper.

• Proceedings of the KIEE Conference
• /
• 2006.07d
• /
• pp.1901-1902
• /
• 2006

In recent years, it has been a worldwide trend that many power utilities gave their attention to develop and operate their power plants, substation and distribution systems. Following this trend, KEPCO(Korea Electric Power Corporation) has developed many electric automation systems with various communication networks. It has been natural that the automation systems are just focused on to remote devices when they come to be designed. But, we have to shift the focus to the automation system itself. We have developed the Multi-service Optical Transmission System (M-OTS) for electrical power systems. It can be adopt to not only distribution power field but also the transmission power field. The result strongly shows that the system is potentially beneficial in reliability, speed, and expandability. This paper presents some of initial design efforts and results toward a KEPCO's communication system in distribution areas.

• Proceedings of the KIEE Conference
• /
• 2006.07a
• /
• pp.62-64
• /
• 2006

With the advent of the international standard IEC 61850 for communication networks and systems in substations, utilities are beginning to implement substation automation systems (SAS) that can give support to interoperability, interchangeability and self-description features. This paper describes with the SAS design accordance with this new standard. After a brief introduction of IEC 61850 SCL, this paper addresses some issues related to the specification of an IEC 61850 based SAS, and describes the Substation Configuration Language (SCL) based on Extensible Markup Language (XML). The SAS design process is explored with examples including the Intelligent Electronic Device (IED) selection, Logical Nodes (LN) allocation and the related services and the SAS communication architecture.

• Proceedings of the Korean Information Science Society Conference
• /
• 2008.06d
• /
• pp.196-201
• /
• 2008

국내에서 추진하고 있는 모바일 RFID 네트워크 서비스는 국외에서 진행하는 단순 물품의 정보에 한정되는 RFID 서비스보다 진보된 서비스이다. 이는 단순히 사물에 대한 정보 서비스가 아니라 핸드폰을 가지고 있는 사람은 모두 대상이 되는 확장성 있는 서비스를 요구한다. 이에 따라 단순 물품에 한정되는 서비스 모델은 모바일 RFID 네트워크 서비스 모델로써 사용될 수 없으며, 개인화된 정보제공을 위한 서비스 모델이 필요하다. 이에 본 논문에서는 모바일 RFID 네트워크에서 핸드폰에 RFID 태그와 리더가 장착된 환경을 가정하여 개인화된 정보제공을 위한 서비스 모델에 따라 서비스에 대한 구성과 그 실행 모델을 제시한다.

• Journal of the Korean Operations Research and Management Science Society
• /
• v.15 no.1
• /
• pp.1-22
• /
• 1990

This susrvey is on modelling of various network design problems with tree configuration, which have a wide variety of practical applications, particularly in communication, which have a wide a variety of practical applications, particularly in communication and transportation network planning. Models which can be classified as either minimum spanning tree of Steiner tree, are investigated. Various important variants of each basic model are then classified according to model structurs. In addition to the calssification, the typical solution method for each problem is briefly sketched, along with some remarks on further research issues.