• 한국정보통신설비학회:학술대회논문집
• /
• 2007.08a
• /
• pp.136-141
• /
• 2007

The frequency accuracy and phase alignment is necessary for ensuring the quality of service (QoS) for applications such as voice, real-time video, wireless hand-off, and data over a converged access medium at the telecom network. As telecom networks evolve from circuit to packet switching, proper synchronization algorithm should be meditated for IP networks to achieve performance quality comparable to that of legacy circuit-switched networks. The Time of Packet (ToP) specified in IEEE 1588 is able to synchronize distributed clocks with an accuracy of less than one microsecond in packet networks. But, The ToP can be affected by impairments of a network such as packet delay variation. This paper proposes the efficient method to minimize the expectable delay variation when ToP synchronizes the distributed clocks. The simulation results are presented to demonstrate the improved performance case when the efficient ToP transmit algorithm is applied.

• International Journal of Contents
• /
• v.17 no.3
• /
• pp.74-83
• /
• 2021

A location-aware algorithm is proposed in this study to optimize the system performance of distributed systems for processing big data with low data reliability and application performance. Compared with previous algorithms, the location-aware data block placement algorithm uses data block placement and node data recovery strategies to improve data application performance and reliability. Simulation and actual cluster tests showed that the location-aware placement algorithm proposed in this study could greatly improve data reliability and shorten the application processing time of I/O interfaces in real-time.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.23 no.12
• /
• pp.210-216
• /
• 2009

Distributed Generation (DG) is predicted to play a important role in electric power system in the near future. insertion of DG system into existing distribution network has great impact on real-time system operation and planning. It is widely accepted that micro turbine generation (MTG) systems are currently attracting lot of attention to meet customers need in the distributed power generation market. In order to investigate the performance of MT generation systems, their efficient modeling is required. This paper presents the modeling and simulation of a MT generation system suitable for stand-alone operation. The system comprises of a permanent magnet synchronous generator driven by a MT. A brief description of the overall system is given, and mathematical models for the MT and permanent magnet synchronous generator are presented. Also, the use of power electronics in conditioning the power output of the generating system is demonstrated. Simulation studies with MATLAB/Simulink have been carried out in stand-alone operation mode of a DG system.

• Journal of the Korea Society for Simulation
• /
• v.23 no.2
• /
• pp.1-6
• /
• 2014

CPS (cyber-physical systems) which consists of connected and diverse embedded systems and physical systems are a new paradigm. Traditional systems were usually considered to be passive and dumb parts in physical systems, but with CPS, we have to take into account what are being moved or changed in the physical systems. So, as increasing the complexity of CPS, potential errors in the systems also increase. In this paper, for enhancing the reliability of CPS, we exploit an executable-model-based design methodology and propose a distributed simulation method to verify the design of CPS. For the design of the systems including discrete and continuous factors, we apply DEV&DESS formalism and simulate models in distributed simulation environments through DDS middleware. We also illustrate the applications of CPS with our modeling tool.

• Proceedings of the Korean Institute of Communication Sciences Conference
• /
• 2006.07a
• /
• pp.593-593
• /
• 2006

• Proceedings of the Korean Information Science Society Conference
• /
• 2003.04d
• /
• pp.400-402
• /
• 2003

복잡하고 특수한 기능을 수행하고 기존의 여러 다른 시스템과 연동해야 하는 내장형 시스템을 저비용 고효율적으로 개발하고 시험 및 평가하기 위해서는 분산 실시간 시뮬레이션 환경이 효과적이다. 또한, 특정한 목적으로 개발된 기존의 이질적인 시뮬레이션 모델들간의 상호호환과 재사용이 요구된다. 이러한 요구 사항을 만족시키고, 내장형 시스템과 시뮬레이션 환경의 연동 및 상호운용의 문제점을 해결하기 위해 HLA(High Level Architecture)기반으로 새로운 시뮬레이션 환경구조, 동작과정 및 운영절차를 제안하고 고찰한다.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.13 no.6
• /
• pp.48-55
• /
• 2005

In this paper, a mathematical model and a simulation method for the response time analysis of Local Interconnect Network(LIN) based network systems are proposed. Network-induced delays in a network based control system can vary widely according to the transmission time of message and the overhead time of transmission. Therefore, in order to design a distributed control system using LIN network, a method to predict and verify the timing behavior of LIN protocol is required at the network design phase. Furthermore, a simulation environment based on a timing model of LIN protocol is beneficial to predict the timing behavior of LIN. The model equation is formulated with six timing parameters deduced from timing properties of LIN specification. Additionally, LIN conformance test equations to verify LIN device driver are derived with timing constraints of the parameters. The proposed model equation and simulation method are validated with a result that is measured at real LIN based network system.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.5
• /
• pp.3421-3425
• /
• 2015

In sensor networks, sensor nodes are usually distributed to manage the networks in continuous unique area, however as by the network property nodes can be located in several areas. The data gathering of distributed nodes to several areas can be different with current continuous area. Hence, the distributed networks can be differently managed to the current continuous networks. In this paper, we describe the data gathering of sensor nodes in distributed sensor areas. It is possible that sensor nodes cannot instantly connect the mobile sink, and the node operation should be considered. The real time data sending to the instant connection scheme of mobile sink can be implemented, but the property of mobile sink should be considered for the sink connection of distributed areas. In this paper, we analyze the proposed scheme by the simulation results. The simulation results show that the overall lifetime to the periodic data gathering method is longer than the threshold method.

• Journal of KIISE:Computer Systems and Theory
• /
• v.30 no.1
• /
• pp.22-32
• /
• 2003

Many of multimedia applications in distributed environments generate the packets which have the real-time characteristics for continuous audio/video data and transmit them according to the teal-time task scheduling theories. In this paper, we model the traffic for continuous media in the distributed multimedia applications based on the high-bandwidth networks and introduce the PDMA algorithm which is the hard real-time task scheduling theory for guaranteeing QoS requested by the clients. Furthermore, we propose the admission control to control the new request not to interfere the current services for maintaining the high quality of services of the applications. Since the proposed admission control is sufficient for the PDMA algorithm, the PDMA algorithm is always able to find the feasible schedule for the set of messages which satisfies it. Therefore, if the set of messages including the new request to generate the new traffic. Otherwise, it rejects the new request. In final, we present the simulation results for showing that the scheduling with the proposed admission control is of practical use.

• Journal of Korea Multimedia Society
• /
• v.15 no.3
• /
• pp.398-407
• /
• 2012

We propose a tree modeling method of expressing realistically and efficiently numerous trees distributed on a broad terrain. This method combines and simplifies the recursive hierarchy of tree branch and branch generation process through self-organizing from buds, allowing users to generate trees that can be used more intuitively and efficiently. With the generation process the leveled structure and the appearance such as branch length, distribution and direction can be controlled interactively by user. In addition, we introduce an environment-adaptive model that allows to grow a number of trees variously by controlling at the same time and we propose an efficient application method of growing environment. For the real-time rendering of the complex tree models distributed on a broad terrain, the rendering process, the LOD(level of detail) for the branch surfaces, and shader instancing are introduced through the GPU(Graphics Processing Unit). Whether the numerous trees are expressed realistically and efficiently on wide terrain by proposed models are confirmed through simulation.