• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.9 no.3
• /
• pp.9-17
• /
• 2009

A Mobile Ad hoc network(MANET) is a network consisting of a set of wireless mobile nodes, which communicate with each other without centralized control or established infrastructure. In this paper, to obtain a better understanding of AODV(Ad hoc On-Demand Distance Vector Routing Protocol)and OLSR(Optimized Link State Routing Protocol) routing protocols, different performances are simulated and analyzed using OPNET modeler 14.5 with the various performance metrics, such as packet delivery ratio, end-to-end delay and routing overhead. As a conclusion, in static analysis, the routing overhead of OLSR is affected by the number of nodes, but not data traffic. In AODV case, it is affected by both data traffic and number of nodes. In mobility analysis, routing overhead is not greatly affected by mobility speed in AODV and OLSR, and the PDR(Packet Delivery Ration) of OLSR is decreased as the node speed increased, while AODV is not changed. AS to delay, AODV is always higher than OLSR in both static and nobility cases.

• JSTS:Journal of Semiconductor Technology and Science
• /
• v.14 no.6
• /
• pp.760-767
• /
• 2014

This paper describes a high-radix crossbar switch design with low latency and power dissipation for Network-on-Chip (NoC) applications. The reduction in latency and power is achieved by employing a folded-clos topology, implementing the switch organized as three stages of low-radix switches connected in cascade. In addition, to facilitate the uniform placement of wires among the sub-switch stages, this paper proposes a Mux-Matrix-Mux structure, which implements the first and third switch stages as multiplexer-based crossbars and the second stage as a matrix-type crossbar. The proposed 256-radix, 8-bit crossbar switch designed in a 65nm CMOS has the simulated power dissipation of 1.92-W and worst-case propagation delay of 0.991-ns while operating at 1.2-V supply and 500-MHz frequency. Compared with the state-of-the-art designs in literature, the proposed crossbar switch achieves the best energy-delay-area efficiency of $0.73-fJ/cycle{\cdot}ns{\cdot}{\lambda}^2$.

• Journal of Institute of Control, Robotics and Systems
• /
• v.4 no.2
• /
• pp.256-263
• /
• 1998

Among process synthesis problems, the heat exchanger network (HEN) has been subjected to the most concentrated effort because this kind of problems was well defined for solving it and 20-30% energy savings could be realized in the present chemical processes. In this paper, we use an evolutionary approach for HEN synthesis because this approach can overcome the local optimum and combine some heuristic rules. The basic evolutionary approach is composed of three parts, that is, initialization step, growth step and mutation step, as in the simulated annealing and genetic algorithm. This algorithm uses the ecological rule that a better cell will live and worse cell should decompose after repeated generations. With this basic concept, a new procedure is developed and a more efficient method is proposed to generate initial solutions. Its effectiveness is shown using test examples.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.61 no.9
• /
• pp.1374-1379
• /
• 2012

Urban rail transit tends to global grounding system in order to control ground potential rise and potential differences between electric equipments. In addition, global grounding system can discharge the large capacity surge current to the ground safely. Since some railway electric equipments are installed all section of line, the global grounding system connected with the connecting grounding wire is more effectively. However, if the fault occurred in the connecting grounding wire area, some dangerous voltage is generated. So, the installation of additional grounding rod will be required. In this study, the global grounding system is simulated using CDEGS program to analyze the divergence spacing of additional ground rod depending on dangerous electric potential characteristics. Grounding net of the each station is modelled in depending on the size of the platform, and the spacing of the connecting grounding rod are compared 50m, 100m, 250m and 400m. Simulation results considering of earth resistivity and underground condition of the connecting grounding wire, spacing of the connecting grounding rod is that less than 250m to spacing of the ground rod was appropriately confirmed.

• Journal of Electrical Engineering and Technology
• /
• v.13 no.1
• /
• pp.521-531
• /
• 2018

This paper presents a procedure for field measurements which provides a generalized Narrowband Power Line Communications (NB-PLC) channel model for low voltage (LV) access network in order to deploy advanced metering infrastructure (AMI) within Lahore, Pakistan. The measurements of allocated sites were performed in the residential (urban and rural), industrial and commercial electricity consumers for the NB-PLC channel modeling of overhead transmission lines (TLs). On the basis of extensive field measurement results, the average attenuation profile and transfer functions are presented. The results obtained from field measurements are validated by comparing them with a proposed Simulink model. A close agreement in the measured and simulated transfer function (TF) results is observed. The proposed Simulink model is an effort to model the NB-PLC channels in an effective way, especially in South Asian countries.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• v.9 no.2
• /
• pp.146-149
• /
• 2005

Confusion of network traffic is increased by increasing of internet user and large of network, Specially olded one and one communication caused loss of bandwidth because of redundant packet by increasing video conference and internet broadcasting. Thereupon multicast technique, method reducing loss of bandwith, for multimedia data transmission was proposed. This paper proposes method to solve overhead problem in the middle router through group management and capsuling with the Xcast technique added Disignated Router(DR). To solve the middle router not supporting IPv6, Xcast using tunneling technique in the IPv6 design and analyze the performance through a simulated examination.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.14 no.5
• /
• pp.1125-1132
• /
• 2010

WiBro(Wireless Broadband Internet) is the standard of high-speed portable internet based on OFDMA/TDD (Orthogonal frequency division multiple access / Time division duplexing) techniques, and the subset of consolidated version of IEEE802.16e Wireless MAN standard. In this paper, we propose performance improvements of WiBro system using the 64QAM SOFM(Self-Organizing Feature Maps)prefiltering. Proposed method used the prefiltering SOFM neural network blind equalization in the Broadband 64 QAM WiBro system receiver. The prefiltering SOFM neural network constellates 64QAM that is transmitter data shape and the blind equalization removes ICI(Inter Carrier Interference). To verificate the proposed method usability, the MSE and the BER are simulated. The simulation results shown that is improved the performances of the proposed WiBro system using the 64QAM SOFM Prefiltering than the existing WiBro system.

• The KIPS Transactions:PartC
• /
• v.13C no.7 s.110
• /
• pp.865-872
• /
• 2006

Cooperative communications (CC) have received a great deal of attention recently as an efficient way to obtain the spatial diversity without physical arrays. Thus, space-time block codes (STBC) which are well-known for use in co-located multi-antenna systems can be still utilized for single-antenna users in a distributed fashion. In this paper, we propose a cooperative signaling structure using the $\frac{3}{4}$-rate STBC and derive closed-form BER expression which takes the effect of network geometry and transmit power constraint into account. A variety of simulated and numerical results demonstrated the cooperation considerably outperforms the direct transmission when partners are located in appropriate positions.

• Nuclear Engineering and Technology
• /
• v.50 no.5
• /
• pp.780-787
• /
• 2018

This article presents a security module based on a field programmable gate array (FPGA) to mitigate man-in-the-middle cyber attacks. Nowadays, the FPGA is considered to be the state of the art in nuclear power plants I&C systems due to its flexibility, reconfigurability, and maintainability of the FPGA technology; it also provides acceptable solutions for embedded computing applications that require cybersecurity. The proposed FPGA-based security module is developed to mitigate information-gathering attacks, which can be made by gaining physical access to the network, e.g., a man-in-the-middle attack, using a cryptographic process to ensure data confidentiality and integrity and prevent injecting malware or malicious data into the critical digital assets of a nuclear power plant data communication system. A model-based system engineering approach is applied. System requirements analysis and enhanced function flow block diagrams are created and simulated using CORE9 to compare the performance of the current and developed systems. Hardware description language code for encryption and serial communication is developed using Vivado Design Suite 2017.2 as a programming tool to run the system synthesis and implementation for performance simulation and design verification. Simple windows are developed using Java for physical testing and communication between a personal computer and the FPGA.

• Korean Journal of Materials Research
• /
• v.11 no.2
• /
• pp.146-150
• /
• 2001

Electromagnetic simulation was compared to the measurement with a network analyzer in the cavity resonator method which has been used for determining microwave quality factor. Scattering matrix $S_{12}$ obtained from the network analyzer was compared to the $S_{12}$ obtained from the simulation. The effects of the pore and the secondary phase of the dielectric resonator on the microwave quality factor were studied. From the simulated results, the dominant resonant $TE_{01\delta}$ mode was determined and the quality factor was observed to decrease with the pore and the secondary phase in the dielectrics.