• Proceedings of the IEEK Conference
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• 2002.07b
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• pp.1070-1073
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• 2002

This study presents a parallel branch-and-bound (PBAB) method for traveling salesman problem (TSP). The PBAB method adopts intermediate form of central control and distributed control in terms of the lightness of the master process's role. Compared with fully distributed control, the control scheme involves less concentration of communication on the master. Moreover, in order to reduce the influence of communication, the worker is composed of a computation thread and a communication thread. The multithreadness realizes the almost blocking free communications on the master. We implement the proposed PBAB method on a network of PCs, which consists of one master and up to 16 workers. We experiment five TSP instances. The results shows that the efficiency increases with the problem size.

• Proceedings of the KIEE Conference
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• 1998.07b
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• pp.772-774
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• 1998

MMIS System of KNGR is composed of systems by using of digital equipment in general, and also interface function among systems is completed by a network. According to this, KNGR PCS also got rid of many kinds of interface cards which have been used for hardwired interface to outside system, and most of function in these cards is to be programmed by PLC. This paper defines the function and method which is to be programmed to PLC. And this paper presents new function which is to be added for operator's interface by using network. It is expected that PCS logic cabinet will be more simplified, satisfy KNGR design concept, and operation convenience will be increased.

• Proceedings of the KIEE Conference
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• 2001.07d
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• pp.2452-2454
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• 2001

KEPRI, the research institute for KEPCO, has started developing a DAS using wireless communication networks since 1999. The wireless networks adopted Radio Link Protocol (RLP) of Personal Communication Service (PCS) as communication protocol. It is the first time that PCS is applied to data networks for DAS. The communication protocol, RLP, makes the DAS networks simple and economically affordable when they are installed at widely dispersed small cities. But, RLP has problem when it send unsolicited message. This paper describes the implementing method of a wireless network using RLP and TCP/IP Network to cope with unsolicited message problem.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 1996.06b
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• pp.101-106
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• 1996

This paper describes the system and network configurations of the Application Development Center for multimedia applications on Korean broadband testbed network. The center is primarily used for developing networked multimedia services funded by the Korean Ministry of Information and Communications. The center is quipped with ATM switch, multimedia workstations and PCs. More than 180 applications for the broadband testbed network are under development. Several examples will be presented in detail.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.37 no.7
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• pp.24-30
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• 2000

In this paper, we proposed an fiber-optic transceivers based on the analog optical transmission techniques of incorporating the SCM (subcarrier multiplexing) and WDM (wavelength-division multiplexing ) method, which can be used to transmission of IMT-2000 and PCS wireless frequency band and analyzed overall those parameters related with fabrication. Especially in the impedance matching network between RF signal and LD, we proposed the method of deriving optimal performance using simulation techniques. In the frequency band of 1.7GHz∼2.25GHz, experimental data for the gain flatness and the noise floor of the optical link were also presented $\pm$1.5dB and -130dBm respectively when the link Rain was 0dB.

• Composites Research
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• v.35 no.1
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• pp.23-30
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• 2022

Polycarbosilane(PCS) is an important precursor for melt-spinning the silicon carbide(SiC) fibers and manufacturing ceramics. The PCS is a metal-organic polymer precursor capable of producing continuous SiC fibers having excellent performance such as high-temperature resistance and oxidation resistance. The SiC fibers are manufactured through melt-spinning, stabilization, and heat treatment processes using the PCS manufactured by synthesis, purification, and control of the molecular structure. In this paper, we analyzed the effect of purification of unreacted substances and low molecular weight through solvent treatment of PCS and the effect of heat treatment at various temperatures change the polymerization and network rearrangement of PCS. Especially, we investigated the complex viscosity and structural arrangement of PCS precursors according to solvent treatment and heat treatment through the rheological properties.

• Journal of KIISE:Computer Systems and Theory
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• v.29 no.2
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• pp.57-64
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• 2002

We implemented two fast PC clusters using fast PCs and high speed network. First. we built the first generation of 16 PC cluster and have used it for real-time operation at Cheju Regional Meteorological Office. Next, we built the second generation of 16PC with dual CUs cluster which was efficiently improved based on performance analysis of the first generation of cluster. In this research we also analyzed performance of two different clusters, which have different CPUs and communication devices using the parallel model MM5 which has been used for the real-time weather forecasting.

• The KIPS Transactions:PartA
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• v.15A no.5
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• pp.249-258
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• 2008

DCDN(Distributed Contents Delivery Network) as known the next generation of CDN is to exploit the resource of client PCs based on P2P technology to provide low cost, high scalability and high speed services when contents are delivered. This DCDN has two problems. One is that DCDN can't provide a sustainable service because client PCs are on/off irregularly and their on times tend to focus on specific time zone, and the other is that client PCs can not be accessed outside in DCDN if they are behind NAT or Firewall. In this paper, we present a distributed contents delivery network based on home gateway for a sustainable service. If home gateway is used in DCDN instead of client PC, it can solve the two existing problems of DCDN. That is, home gateway can provide a sustainable service because it is on during all day and it is not behind NAT and Firewall. The proposed method is implemented with ASUS WL-500GP, a wired/wireless router. Experimental results show the effectiveness of the proposed method compared to the existing method of DCDN.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.10
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• pp.1150-1156
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• 2007

In this paper, two novel subsurface antennas for remote management of underground facilities using PCS and cellular wireless network are proposed. The proposed subsurface antenna is a dual band circular patch which is inserted and molded for the protection of the antenna into a metal such as a manhole cover. The antenna is designed considering the resonant frequency shift of the antenna due to the insertion and molding. The measured return loss and receiving power of the fabricated antenna comparison with a dipole shows that two proposed subsurface antenna can be used for remote management of underground facilities using PCS and cellular systems.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.21 no.3
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• pp.101-115
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• 2011

A botnet is a huge network of hacked zombie PCs. Recognizing the fact that the majority of email spam is sent out by botnets, a system that is capable of detecting botnets and zombie PCS will be designed in this study by analyzing email spam. In this study, spam data collected in "an email spam trail system", Korea's national spam collection system, were used for analysis. In this study, we classified the spam groups by the URLs or attached files, and we measured how much the group has the characteristics of botnet and how much the IPs have the characteristics of zombie PC. Through the simulation result in this study, we could extract 16,030 zombie suspected PCs for one hours and it was verified that email spam can provide considerably useful information in tracing zombie PCs.