• 음성과학
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• 제11권4호
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• pp.67-73
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• 2004

Packet loss, jitter, and delay in the Internet are caused mainly by the shortage of network bandwidth. It is due to queuing and routing process in the intermediate nodes of the packet network. In the Internet whose bandwidth is changing very rapidly in time depending on the number of users and data traffic, controlling the peak transmission bit-rate of a VoIP. system depending on the channel condition could be very helpful for making use of the available network bandwidth. Adapting packet size to the channel condition can reduce packet loss to improve the speech quality. It has been shown in [1] that a VoIP system with an AMR speech codec provides better speech quality than VoIP systems with fixed rate speech codecs. With the adaptive codec mode assignment. algorithm proposed in [1], in this paper, we performed the voice transmission experiments using the wireless LAN through the real Internet environment. Experimental results are analyzed and discussed with our findings.

• Journal of Electrical Engineering and Technology
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• 제9권4호
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• pp.1375-1384
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• 2014

Flashover of power transmission line insulators is a major threat to the reliable operation of power system. This paper deals with the flashover prediction of polymeric insulators used in power transmission line applications using the novel condition monitoring technique developed by PD signal time-frequency map and neural network technique. Laboratory experiments on polymeric insulators were carried out as per IEC 60507 under AC voltage, at different humidity and contamination levels using NaCl as a contaminant. Partial discharge signals were acquired using advanced ultra wide band detection system. Salient features from the Time-Frequency map and PRPD pattern at different pollution levels were extracted. The flashover prediction of polymeric insulators was automated using artificial neural network (ANN) with back propagation algorithm (BPA). From the results, it can be speculated that PD signal feature extraction along with back propagation classification is a well suited technique to predict flashover of polymeric insulators.

• 전기전자학회논문지
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• 제5권1호
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• pp.35-42
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• 2001

This paper deals with an architecture of network-based control system using the CAN(Controller Area Network) protocol and its traffic analysis. It is difficult to determine an optimal network-based control architecture for a specific AGV(Autonomous Guided Vehicle) system with a manipulator arm. The fixed number of periodic messages to be occurred is pre-defined in the system. To determine whether the proposed system architecture is effective or not, we perform traffic analysis for the real-time communication of all messages. Through simulations, the range of transmission speed is found satisfying required conditions and the permissible number of additional sensors is investigated for improving the system performance, when the sampling periods of analog sensors are determined under fixed condition that the transmission speed is over 500Kbps.

• 한국정보통신학회논문지
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• 제26권9호
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• pp.1320-1329
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• 2022

현재 선도국가연구망 그룹에서 SDN/NFV 기반의 네트워크 자동화·지능화 기술을 사용자에게 서비스 형태로 제공하기 위한 요구가 지속적으로 발생함에 따라 관련 연구개발이 추진되고 있다. 또한, 선도국가연구망에서는 일반 네트워크 환경보다 대용량 데이터 전송을 고성능으로 제공해야 한다는 요구사항이 점차 더 커지고 있는 실정이다. 이에 따라, 본 논문에서는 이러한 국가연구망의 네트워킹 요구사항들에 대응하기 위하여 연구 개발한 대용량 데이터 전송을 위한 오픈 API 기반 가상 네트워크 프로비저닝 자동화 플랫폼을 제안하고 이의 구현 결과를 제시한다. 해당 플랫폼에는 SDN 기반의 네트워크 가상화 기술을 제공하는 KREONET-S의 VDN 시스템, 컨테이너 중심의 서버 가상화 기술을 제공하는 Kubernetes 시스템, 그리고 고성능 데이터 전송 시스템인 Globus Online이 포함되어 있다. 본 논문에서는 이러한 상이한 시스템 간의 연계를 위한 환경 설정 및 시스템 연동 결과, 가상 네트워크 프로비저닝 자동화 구현 결과 및 성능에 대하여 보인다.

• 한국인터넷방송통신학회논문지
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• 제12권5호
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• pp.255-260
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• 2012

현재 운영되는 주요 하 폐수 처리시설 관리에 있어 환경 보호를 위한 엄격한 규제로 수질오염 측정 시스템에 관한 시스템이 부각되고 있다. 하지만 기존 하 폐수 처리 시스템은 하 폐수에 특화된 수질감시 기술이 미흡하며, 그중 센서와 네트워크를 통한 1:n 데이터 전송이 아닌 1:1을 지향하며, 이기종간 통신방식에 대한 호환성이 미비하다. 또한, 주로 수동방식의 검출방식을 준수하고 있다. 이에 본 논문에서는 수질복원시설물 내에 자동화된 센서 네트워크 통합 인터페이스를 위한 센서와 수질감지통합인터페이스간의 효율적인 데이터 전송에 관한 프로토콜 기술에 관해 연구하였다. 센서 네트워크 통합 인터페이스용 모니터링 구현을 통해 이기종간 통신방식으로 원활한 데이터 전송이 가능함을 입증하였다.

• 상하수도학회지
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• 제33권5호
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• pp.329-339
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• 2019

Recently, the advancement of information and communication technology(ICT) is expanding the connectivity through Internet of Things(IoT), and the media of connection is also expanding from wire/cable transmission to broadband wireless communication, which has significantly improved mobility. This hyperconnectivity has become a key element of the fourth industrial revolution, whereas the supervisory control network of purification plants in korea is operated as a communication network separated from the outside, thereby lagging in terms of connectivity. This is considered the best way to ensure security, and thus there is hardly any consideration of establishing alternatives to operate an efficient and stable communication network. Moreover, security for management of a commercialized communication network and network management solution may be accompanied by immense costs, making it more difficult to make new attempts. Therefore, to improve the conditions for the current supervisory control network of purification plants, this study developed a industrial security L2 switch that supports modbus TCP(Transmission Control Protocol) communication and encryption function of the transmission section. As a result, the communication security performance improved significantly, and the cost for implementing the network management system using Historical Trend and information of HMI(Human Machine Interface) could be reduced by approximately KRW 200 million. The results of this study may be applied to systems for gas, electricity and social safety nets that are infrastructure communication networks that are similar to purification plants.

• 인터넷정보학회논문지
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• 제20권2호
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• pp.21-27
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• 2019

The terrestrial ATSC 3.0 broadcasting system, which is capable of converging broadcast and communication services, uses IP based technology for data transmission between broadcasting equipment. In addition, data transmission between broadcasting equipment uses IP-based technology like existing wired communication network, which has advantageous in terms of equipment construction and maintenance In case IP based data transmission technology is used, however, it may inevitably cause an error that a packet is lost during transmission depending on the network environments. In order to cope with a broadcasting accident caused by such a transmission error or a malfunction of a broadcasting apparatus, a broadcasting system is generally configured as a duplication, which can transmit a normal packet when various types of error may occur. By this reason, correction method of error packets and intelligent switching technology are essential. Therefore, in this paper, we propose a design and implementation of intelligent IP switch for Ensuring Reliability of ATSC 3.0 Broadcast Streams. The proposed intelligent IP consists of IP Stream Analysis Module, ALP Stream Analysis Module, STL Stream Analysis Module and SMPTE 2022-1 based FEC Encoding/Decoding Module.

• 대한전기학회논문지:시스템및제어부문D
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• 제51권7호
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• pp.294-301
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• 2002

A new dynamic scheduling algorithm is proposed for CAN-based real-time system in this paper. The proposed algorithm is extended from an existing EDS(Earliest Deadline Scheduling) approach having a solution to the priority inversion. Using the proposed algorithm, the available bandwidth of network media can be checked dynamically, and consequently arbitration delay causing the miss of deadline can be avoided. Also, non-real time messages can be processed with their bandwidth allocation. Full network utilization and real-time transmission feasibility can be achieved through the algorithm. To evaluate the performance of algorithm, two simulation tests are performed. The first one is transmission data measurement per minute for periodic messages and the second one is feasibility in the system with both periodic messages and non-real time message.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2004년도 춘계종합학술대회
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• pp.420-423
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• 2004

컴퓨터 기술의 발달과 더불어 인터넷의 발전은 고속화되어 왔다. 이에 따라 데이터 전송 속도의 과속화와 대용량의 데이터 전송 둥의 기술이 증가되고 이로 인해 업무 효율을 향상됨에 따라 시스템 및 네트워크 차원에서 보안 기능에 대한 요구도 날로 증가하고 있다. 따라서 본 논문에서는 정보통신망 자체를 사이버 공격으로부터 보호하며, 정보통신망의 보안 취약점을 없애 해킹이나 정보유출을 원천적으로 차단할 수 있는 능동형 보안 관리 기술인 역추적 시스템을 분석하고 액티브 네트워크 기반의 역추적 시스템을 분석 및 설계하였다.

• 한국시뮬레이션학회논문지
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• 제8권2호
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• pp.101-109
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• 1999

In a commercial facsimile network system, a simulation analysis has been performed using ARENA due to the unavailability of theoretical models. The effect of a priority is compared with that of the current FCFS rule on the arriving call blocking rate and transmission time delay. The result shows that the priority rule reduces more service time delay as the arrival rate increases. A simulation analysis procedure is proposed to select optimal in/out port ratio at various hourly arrival rates with a given multiple-place transmission requests ratio.