• Proceedings of the KSR Conference
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• 2011.10a
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• pp.1014-1019
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• 2011

The substation automation is a system to remote-monitor and control electric power flow. And in line with electrification of railway, an interest in electric railway substation automation is increasing. IEC standardized IEC 61850, IEC 61968 and IEC 61970 communication protocol for the telecommunication standardization of the electric power automation industry. The recent SCADA systems in managed electric railway substations are have the problem about the compatibility with the products which fit to the international standard specification afterward. In this paper, the model of electric railway substation automation based on IEC 61850 and IEC 61970 is presented. And the method supporting the compatibility between the equipment is proposed.

• ETRI Journal
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• v.37 no.1
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• pp.175-185
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• 2015

This paper presents a system-of-systems (SoS) approach to the formal modeling of a cyber-physical system (CPS) for simulation-based analysis. The approach is based on a convergence technology for modeling and simulation of a highly complex system in which SoS modeling methodology, hybrid systems modeling theory, and simulation interoperation technology are merged. The methodology maps each constituent system of a CPS to a disparate model of either continuous or discrete types. The theory employs two formalisms for modeling of the two model types with formal specification of interfaces between them. Finally, the technology adapts a simulation bus called DEVS BUS whose protocol synchronizes time and exchange messages between subsystems simulation. Benefits of the approach include reusability of simulation models and environments, and simulation-based analysis of subsystems of a CPS in an inter-relational manner.

• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.523-526
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• 1998

In an ongoing project at ETRI-CSTL, A debugger for distributed programs that run on a varied collection of machines is being built. To build such debugger, a clientserver model is incorporated. This strategy enables us to provide a unified user interface and isolate debugger core from the user interface. Several debugging servers running on a diverse set of platforms permit the implementation of a distributed debugger for heterogeneous environment, and the single debugging client provides unified debugging concept and graphical user interface over various servers. Also, the precise specification of the interaction protocol between the client and server facilitates client to be paired with a variety of server implementantations. This paper describes the design and implementation of our debugger, concentrating on the system architecture.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.809-813
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• 2004

In this paper, we developed a network camera for CMOS camera module inspection. The design, implementation details including embedded linux porting and CPLD logics, and performance of network camera are described. The network camera consists of SoC(S3C4530A), CPLD and CMOS image sensor. In order to image data of CMOS image sensor we designed capture logics on CPLD by using VHDL program. Embedded Linux such as uClinux is performed on the network camera to utilize development environment and TCP/IP protocol specification. The application is based on socket communication between GUI on PC and Embedded Linux based network camera. When JPEG compression is applied, the transmission speed was improved enough for this system to be used for an alternative of expensive CCTV or remote monitoring system in a power plant and uninhabited places.

• Proceedings of the KIEE Conference
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• 2008.11a
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• pp.339-341
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• 2008

본 논문은 변전소자동화(Substation Automation : SA)의 국제표준화 동향에 맞추어, IEC61850이라는 국제표준 Protocol을 탑재한 여러 Device의 통신 환경을 구축하기 위해서 개발된 MMS Server Simulator 개발에 관한 소개이다. 본 연구를 통해 개발된 MMS Server Simulator는 MMS(Manufacturing Message Specification) Server의 기능과 함께 Report Control Block, GOOSE (Generic Object Oriented Substation Event) Publisher 등의 기능을 가지고 있다.

• Journal of Korea Multimedia Society
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• v.19 no.12
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• pp.1992-1999
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• 2016

In layered communication architecture, each layer is designed to service its own functions to higher layer while getting serviced by lower layer. Usually layered architectures are not optimized in a total view of whole services and functions. So cross layer design pursues performance enhancements by optimizing in various ways. In LTE, MAC layer uses HARQ mechanism and RLC layer uses ARQ mechanism for retransmission. According to the 3GPP 36.331 specification, two layers' cooperation may not happen in an optimized way. This paper suggests an adaptive MAC layer approach which RLC layer's function might be initiated in MAC layer in advance to utilize MAC layer's idling wasting time for RLC layer's next decision. This adaptive ARQ method in MAC layer speeds up the next retransmission and reduces the overall transmission time. Emulation shows the improved performance in total retransmission time and retransmission success ratio. In wireless shadow area, the retransmission occurs frequently. Our approach has strong points in this poor wireless condition.

• Proceedings of the Korean Information Science Society Conference
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• 2004.10c
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• pp.706-708
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• 2004

일반적인 무선 통신망은 데이터 전송 고속화에 중심을 두고 발전해 왔으나, 최근 무선 센서 네트워크와 같은 응용 분야에서 소량의 데이터와 낮은 처리 속도를 지원하면서 저비용, 경량, 저전력을 요구하는 무선 통신 기술이 필요하게 됨에 따라 IEEE에서 LR-WPAN(Low Rate-Wireless Personal Area Network)을 위한 새로운 IEEE 802.15.4 표준이 제시되었다. 현재 무선 센서 네트워크에 관한 연구는 소형 경량의 MAC(Medium Access Control ) 프로토콜 개발이 핵심 기술로 인식되면서, 저전력 소모를 위한 라우팅 기법, MAC 프로토콜의 패킷처리 기술 등이 우선적으로 진행 중이다. 그러나 무선 센서 네트워크와 같은 응용분야에 사용 가능한 표준인 IEEE 802.15.4 MAC 프로토콜의 실질적인 상용화를 위해서는 표준안 분석 및 검증 과정이 기본적으로 선행되어야 한다. 본 논문에서는 IEEE 802.15.4 표준안의 핵심인 MAC 프로토콜을 정형화된 명세 언어인 SDL(Specification and Description Language)를 이용하며 상세 설계 및 분석 후, 자동화 도구를 이용한 모의수행을 통하여 검증하였으며 표준안과의 비교 및 오류 수정을 거친 연구결과를 기술한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.7B
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• pp.1253-1259
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• 2000

적합성 시험은 프로토콜 구현물인 IUT(Implementation Under Test)가 프로토콜 규격과 일치하는지를 검증하는 것으로, 이 적합성 시험의 질은 생성된 시험열에 의존한다. 기존에는 시험열 생성이 수작업으로 이루어지기 때문에 오류의 가능성을 내포한다. 본 논문에서는 자동화된 툴(tool)인 Design/CPN을 이용하여 SDL(Specification and Description Language)로 기술된 프로토콜의 시험열을 생성한다. SDL로 기술된 프로토콜을 자료흐름을 고려한 CPN(Colored Petri Nets)으로 변환 후 Design/CPN에 입력하여 자동 생성된 OG(Occurrence Graph)와 디스크립터 (descriptor)로부터 시험열을 생성함으로써, 기존의 시험열 생성 방법에 비해 오류 가능성을 줄일 수 있으며, 자료 흐름이 고려된 시험열을 얻을 수 있다.

• Proceedings of the Korean Information Science Society Conference
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• 2008.06d
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• pp.318-321
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• 2008

현재의 소프트웨어 개발은 구현 중심의 개발에서 설계 중심의 개발로 바뀌고 있다. 설계 중심의 개발은 구현 프로그램의 시스템 개발 시간을 크게 단축할 수 있고, 정형화된 명세를 검증함으로써 설계와 구현의 일관성을 유지할 수 있으며 유지 보수가 효율적이다. 이러한 설계 중심의 개발에 있어서 SDL(Specification and Description Language)은 표준으로 재정된 기술을 구현하는데 있어 어떠한 기준 명세라 할 수 있다. 하지만 이러한 SDL도 대다수의 사람이 쉽게 알아보기에는 어려움이 있기 때문에 좀 더 높은 범용성을 위해 본 논문에서는 엔지니어들이 보편적으로 많이 사용하는 언어인 c언어를 이용해 SDL을 직접적으로 구현 해 보았는데 점점 더 발전해가는 Wireless LAN의 표준인 IEEE 802.11의 spec에 명시되어 있는 SDL을 기반으로 MAC 부분을 구현하였다.

• ETRI Journal
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• v.26 no.4
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• pp.360-366
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• 2004

Synchronization Markup Language (SyncML) is a specification of a common data synchronization framework for synchronizing data on networked devices. SyncML is designed for use between mobile devices that are intermittently connected to a network and network services that are continuously available on the network. We have designed and developed a data synchronization system based on the SyncML protocol and evaluated the throughput of the system using the stochastic Petri nets package (SPNP) and analyzed the relationship between the arrival rate and the system resources. Using this model, we evaluate various performance measures in different situations, and we estimate the relationship between the arrival rate and the system resources. From the results, we can estimate the optimal amount of resources due to the arrival rate before deploying the developed system.