• Proceedings of the KIEE Conference
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• 2003.11c
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• pp.437-440
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• 2003

Recently, the study on the design of NCS(Network Control System) using Ethernet is being rapidly progressed. NCS can be extensively applied in manufacturing automation, office automation, home automation, remote control and ect. A merit of NCS on based Ethernet is to make good use of advanced Internet environment and to apply a application of abundant TCP/IP upper layer to NCS. The purpose of this paper is to control a speed of DC-motor using NCS on based Ethernet. The control system is divided into a server part and a client part. A server transfers a value of reference speed of a DC-motor. A client receives a output signal of DC-motor and a reference input obtained from the server. A client computes a error of two signals and then makes a control input. The control input is transferred to a actuator In this pater, A controller uses a classical control using a general feedback. In this paper, a viewpoint is to compare performance of NCS with performance of a classical control and to analyze the cause of that.

• Proceedings of the Korean Information Science Society Conference
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• 2003.10a
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• pp.808-810
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• 2003

정보보호 기능을 필요로 하는 각종 응용분야에서 다양한 보안 API가 사용되고 있다. 그러나 이러한 표준은 서로 호환성을 가지고 사용될 수 있는 것이 아니라 애플리케이션의 적용환경이나 프로그래밍 언어에 따라서 개발자가 선택적으로 이용해야 하는 단정을 가지고 있다. 이를 해결하기 위하여 정보보호 서비스컴포넌트 표준화를 진행하고 있으며 표준안의 유효성을 검증하기 위하여 비밀성, 무결성 컴포넌트 인터페이스를 통한 SSL(Secure Sockets Layer)을 구현하였다. 구현된 SSL은 TCP/IP 위에 하나의 단계를 추가하여 보안 알고리즘을 구현하는 것처럼 실제 컴포넌트간에 RMI(Remote Method Invocation)로 통신을 할 때, 각각 하위 수준의 SSL 컴포넌트를 이용하는 구조이다.

• Journal of the Korea Institute of Military Science and Technology
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• v.11 no.3
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• pp.106-114
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• 2008

In this paper we suggest a protocol and an algorithm which connect a secure channel between a server and a client over a TCP layer. To make key exchange time the most quickly, the protocol adopts ECC Diffie Hellman(ECCDH) algorithm. And the protocol does not use Hello message for key exchanges and state changes. We also implement this protocol over an open TCP/IP program and check the secure channel connecting time over the military computer network. The suggested protocol could be practically used on the military computer network without a hardware implementation.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.6
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• pp.1183-1190
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• 2018

The environmental regulations are being strengthened all over the world, and the introduction of electric vehicles are actively being considered to cope with them effectively. It is essential to establish a charging infrastructure, which is an essential element of electric vehicle distribution. In this paper, power line communication technology essential for smart charging infrastructure is studied. A control board capable of achieving a physical layer speed of 10Mbps and a TCP/IP layer of 4.5Mbps, which conforms to the ISO/IEC 15118 international standard, and a control board mounted on the board and compliant with international standards. We have developed a software solution to perform functions for linking. In addition, in order to be applied to the combo-type DC fast charger, the hardware was designed to meet the industrial environment standard and the V2G communication module was developed by integrating it with the software solution.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.21 no.1
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• pp.39-52
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• 2011

An application-layer attack can effectively achieve its objective with a small amount of traffic, and detection is difficult because the traffic type is very similar to that of legitimate users. We have discovered a unique characteristic that is produced by a difference in client intention: Both a legitimate user and DDoS attacker establish a session through a 3-way handshake over the TCP/IP layer. After a connection is established, they request at least one HTTP service by a Get request packet. The legitimate HTTP user waits for the server's response. However, an attacker tries to terminate the existing session right after the Get request. These different actions can be interpreted as a difference in client intention. In this paper, we propose a detection algorithm for application layer DDoS attacks based on this difference. The proposed algorithm was simulated using traffic dump files that were taken from normal user networks and Botnet-based attack tools. The test results showed that the algorithm can detect an HTTP-Get flooding attack with almost zero false alarms.

• Journal of Communications and Networks
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• v.4 no.4
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• pp.266-281
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• 2002

The General Packet Radio Service (GPRS) is being deployed by GSM network operators world-wide, and promises to provide users with “always-on” data access at bandwidths comparable to that of conventional fixed-wire telephone modems. However, many users have found the reality to be rather different, experiencing very disappointing performance when, for example, browsing the web over GPRS. In this paper, we examine the causes, and show how unfortunate interactions between the GPRS link characteristics and TCP/IP protocols lead to poor performance. A performance characterization of the GPRS link-layer is presented, determined through extensive measurements taken over production networks. We present measurements of packet loss rates, bandwidth availability, link stability, and round-trip time. The effect these characteristics have on TCP behavior are examined, demonstrating how they can result in poor link utilization, excessive packet queueing, and slow recovery from packet losses. Further, we show that the HTTP protocol can compound these issues, leading to dire WWW performance. We go on to show how the use of a transparent proxy interposed near the wired-wireless border can be used to alleviate many of these performance issues without requiring changes to either client or server end systems.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.11A
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• pp.1051-1058
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• 2010

Mobile IP (MIP) and SIP are considered as important technologies to provide the macro mobility in the next generation mobile convergence networks which have heterogeneous access networks. Typically, MIP and SIP are more suitable for the non-real-time TCP connections and the real-time RTP/UDP sessions respectively, hence a handset which uses both of these sessions should simultaneously apply MIP and SIP to perform the efficient mobility management. Existing multi-layered mobility management schemes focus on the signalling order of each protocol. However, simple combining of two protocols cannot provide the performance enhancement of the mobility management. In this paper, a novel multi-layered mobility management algorithm using the combination of SIP and fast MIPv6 (FMIPv6) is proposed. FMIPv6 and SIP mobility is simultaneously performed to reduce the service interrupt time and to guarantee QoS requirement. The delay model is defined to analysis the performance of the algorithm and the simulation results show the performance of the proposed algorithm.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.602-605
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• 2001

This paper focus on a method to use Ethernet Network for Industrial Communication Network. Ethernet use the CSMA/CD MAC(Medium Access Control) Protocol at the Data-Link Layer, Which isn't suit for Industrial Communication Network requiring Real-Time Communication, periodic data processing, critical data processing characteristics. In this paper we proposed the Virtual Polling Algorithm at the Application Layer will be solution of using the Ethernet Network for the Industrial Communication Network, Proposed Algorithm terminate the Collision in the network thus Delay Time is reduced and Real-Time Communication will be implemented.

• Proceedings of the Korean Society of Computer Information Conference
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• 2010.07a
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• pp.525-526
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• 2010

2000년 대규모 DDoS 공격이래, 2009년 7월 7일 국가주요정부기관 및 인터넷 포털, 금융권 등의 웹사이트 대상으로 1차, 2차, 3차로 나누어 대규모 사이버 공격이 발생하였다. 지속적으로 발전되는 행태를 보이고 DDoS 공격에 대해 본 논문에서는 계층적인 침입탐지시스템을 설계하였다. 네트워크 패킷을 분석하기 위해 e-Watch, NetworkMiner등의 패킷, 프로토콜 분석도구를 이용하여 TCP/IP의 Layer별 공격을 분석한 후 패킷의 유입량, 로그정보, 접속정보, Port, Address 정보를 분석하고 계층침입에 대한 방어를 수행하도록 설계하였다. 본 논문은 DDoS(Distributed Denial of Service)에 대한 패킷 전송에 대해 계층적인 방어를 통해 보다 안정적인 패킷수신이 이루어진다.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.362-367
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• 2005

Control network adopted in the national power-plant or manufactory are mostly vendor-dependent products, which have their own special specification, components and individual communication methods. These systems not only raise installation cost, but also bring many difficulties to maintenance and extension. To overcome these problems, this paper introduces a development and application case of a new "PC/Ethernet-based fieldbus" architecture and protocol to be used in mid-level fieldbus. The designed system has a basic idea of "3 Layers fieldbus over Standard-LAN" and implemented on PCs. PC gives user friendly environment. By using an open standard Ethernet in layer 1,2, the system has low cost, wide communication bandwidth and high compatibility. Layer 3 protocol designed for large realtime data communication makes user bypass TCP/IP layer and gives user direct access to the Ethernet. This new protocol eliminates potential collision of Ethernet, and transmits large periodic/non-periodic control data by using long-frame/wide-bandwidth of Ethernet effectively, and offers simple API-Services to the upper layer. Since the system have installed in H-power plant simulator and U-nuclear power plant simulator in Korea, it have been proved to be efficient and stable without any trouble in realtime communication service for full-scope plant simulator that has a lot of control elements.