• Journal of Communications and Networks
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• 제14권5호
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• pp.510-517
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• 2012

This paper analyzes the performance of voice-over-Internet protocol (VoIP) services in terms of the system throughput, the packet delay, and the signaling overhead in a mobile WiMAX system with a hybrid automatic repeat request (HARQ) mechanism. Furthermore, a queueing analytical model is developed with due consideration of adaptive modulation and coding, the signaling overhead, and the retransmissions of erroneous packets. The arrival process is modeled as the sum of the arrival rate at the initial transmission queue and the retransmission queue, respectively. The service rate is calculated by taking the HARQ retransmissions into consideration. This paper also evaluates the performance of VoIP services in a mobile WiMAX system with and without persistent allocation; persistent allocation is a technique used to reduce the signaling overhead for connections with a periodic traffic pattern and a relatively fixed payload. As shown in the simulation results, the HARQ mechanism increases the system throughput as well as the signaling overhead and the packet delay.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제52권8호
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• pp.397-404
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• 2003

In part I, we studied only step speed control for train, the second part extended to beacon signaling system and moving block system. With the calculated braking distance in part I, part II showed how to reduce headway using the beacon signaling system and moving block system, revealed that the beacon system has a braking distance advantage for sighting allowance with compared to step speed control, proposed beacon installation interval and revealed the braking distance with moving block system being nearly approached to train pure braking distance. We compared three different train control system to decide the best signaling system for a given condition and obtained the result that three systems have a same headway near 10～13 steps speed control.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 춘계학술대회 논문집
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• pp.262-265
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• 2007

This paper is about the study on the failure mode identification of railway signaling embedded system thru which quantitative reliability and safety can be compared reciprocally. Frequency of each failure mode makes possible to compare the reliability of each system and frequency of dangerous failure is used as the measurement standards for system safety. Therefore, this paper provides both reliability-related failure mode and safety-related failure mode by modeling the railway signaling embedded system.

• 전기학회논문지
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• 제64권7호
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• pp.1019-1025
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• 2015

The performance requirements on the safety-based functionality of railway signal systems have been reinforced and the effort for enhancement of the existing system or development of the new system is being accordingly made. In particular, various technical researches on replacement or improvement of the existing ATS(Automatic Train Stop) signaling system are now in progress for better operational efficiency. In this study, the complementary points for improvement or replacement of the currently used system(i.e., ATS) will be derived in terms of operating efficiency in an integrated operating environment with the newly introduced system(e.g., ATC: Automatic Train Control). This study can contribute to derive the need for improvement of the signaling system by checking the interface problems and comparing between different systems through the analysis of real operation cases in the field. Eventually, this analysis can be applied to prevent and estimate the collision accidents can be caused by the failure of the signaling system in advance. In addition, the results can be used to provide a future direction to secure the reliability in the parallel operation by integration based on different railway signaling systems.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제55권9호
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• pp.485-490
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• 2006

According to the computerization of railway signaling systems, the interface link between the signaling systems has been replaced by the digital communication channel. At the same time, the importance of the communication link is more pronounced than before. In this paper, new Network-based protocol between railway signaling and SCADA (Supervisory Control and Data Acquisition system) has designed and the overview of designed protocol is briefly represented. And also this paper addresses analysis of newly designed train control systems. Fame error rates of the data transmissions are calculated and compared for the two cases that the CTC (Centralized Traffic Control)/SCADA has an extra data transmission error control (CRC16) besides the inherent error control of the Ethernet and that the CTC/SCADA has no extra data transmission error control. With simulation results it has been verified that the additional error control code contributes to lowering the frame error rate. It will be expected to increase the safety, reliability and efficiency of maintenance of the signaling systems by using the designed protocol for railway signaling system.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1998년도 추계종합학술대회 논문집
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• pp.207-210
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• 1998

Providing the connectivity interworking between the lightweight signaling function using in VOD set-top box and the broadband signaling function In the access node system, it can diminish the cost-burden of user about set-top box and we shall use efficiently the network resources. Therefore, In this paper, we shall design the signaling brokerage agent function for the connectivityinterworking in access node system and discuss the result applied its function to the real-time VOD service.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.239-244
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• 2011

Technical advancement in the field of world-class railway has brought the development of passenger safety, efficient operation and fast passenger service. The study of the railway speed-up has been progressed for a long time. As for the speed-up of trunkline railways, its design work has already promoted in some railway tacks and some track sections has already been under construction. In such a perspective we should review if the domestic signaling system is the optimal system and figure out the trend of signaling system for the speed-up that is recently applied over the world. In this way learning about justification and futurition, we should secure the national competitiveness in the long term and review the system available to international exports. Further, it is important to apply the result to the research project currently being pursued. In addition, predicting the recent international trends, we should show the direction of the future-oriented and economic signaling system.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 춘계학술대회 논문집
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• pp.519-534
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• 2008

The Maglev travels at levitated status from the rail in some gab (about $8\sim10mm$). it make difference with the existing subway or the another LRV. The detection method of the train speed and the train position to be used at Maglev's signaling system differ with the existing subway or the another LRV's. so, the signal system construction of the new method is necessary. This paper describes the configuration and characteristic of the total signaling system (TTC/Wayside/Cab/Guide way system etc.) developed for Maglev, and the design concept of the signaling system based on the latest wireless LAN communication for driverless operation.

• 대한전자공학회논문지TC
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• 제42권1호`
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• pp.49-60
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• 2005

유무선 기간 망에서 사용되어 지는 Core Network System간 연동 부분의 Back Bone이 NO.7 Protocol이다. 그래서 유선망에서 기본적인 중계 ISUP이나, 지능망 INAP 처리, 그리고 이동망에서 각 Network Element System간 연동되는 MAP 연동 방식이 NO.7 방식을 사용하고 있다. 따라서 이 NO.7을 이용하는 Core Network에서 운영 중에 장애가 발생하거나, 기존에 인지되지 않고 지나온 문제점들을 최단시간에 감지하여 도출할 수 있는 시스템이 필요로 되었다. 본 논문에서는 Core Network 에서 사용되는 NO.7 Signaling 방식에 대해 더욱 신뢰성을 확보하고, 장애 발생 여부 등을 분석할 수 있도록 하기 위하여 NO.7 Signaling Message들을 추출하여 Core Network 시스템의 기능 및 성능을 분석하고 Report를 작성할 수 있는 NO.7 Protocol 분석 측정 시스템을 고안하였다. 이 시스템은 NO.7 Signaling을 담당하는 Core Network 시스템의 NO.7 HW Module 에 연결하여 Monitoring만 수행하고, 어떤 시나리오에 대한 Emulator 기능이나 Simulation 기능은 제공하지 않는다. 이 시스템은 현재 NO.7 MTP, ISUP, INAP, 그리고 MAP 에 대해 측정 및 분석기능을 수행하도록 하였고, 여러 유무선 기간 망 사업자에 제공하여 SW 및 HW 적인 면 그리고 운영적인면 등에서 여러 가지 문제들을 확인하여 교정할 수 있었다. 향후에는 이외에 BSC-MSC 연동되어 지는 A-Interface 등과 같은 기능도 제공함으로써 NO.7 Protocol 전반적인 분석과 동시에 Core Network 시스템에 효율적인 운영을 도모할 수 있다.

• 한국철도학회논문집
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• 제7권2호
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• pp.114-119
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• 2004

According to the computerization of railway signalling systems. the communication protocol for interface between these systems are required. Therefore the new communication protocol for railway signaling system is required. Generally, there are two verification method for new designed protocol in the industrial and academic fields. One is the laboratory testing method which is very popular and general technique. In our research the comparison between existing and new designed protocol for signaling is described and the verification test results are also represented. From these laboratory test, we are verified the conformance of new designed protocol. Another method is verified by formal method. The format verification method is widely used at safety-critical system design but this approach is nor popular at verification communication protocol. However it is very important to verify the safety of new designed protocol for railway signaling system because signaling systems are very safety-critical systems. So, the methodology for formal verification of designed protocol is also reviews in this paper.