• Journal of information and communication convergence engineering
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• v.12 no.1
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• pp.1-7
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• 2014

A novel design of a simple circular ring with open-ended monopole antenna for wireless local area network (WLAN) applications is proposed in this article. The proposed antenna consists of an open-ended circular ring and $50-{\Omega}$ microstrip feed-line. The proposed antenna is capable of generating two separate resonant modes with good impedance-matching conditions. A prototype of the proposed antenna is designed, fabricated, and measured. Acceptable agreement between the measurement and simulation results is achieved. Experimental results show that the proposed antenna has operating bandwidths of 1.99-3.04 GHz and 5.08-6.1 GHz with a return loss of less than -10 dB, covering the required bandwidths of the 2.4/5.2/5.8-GHz WLAN standards. This is a microstrip antenna for IEEE 802.11a/b wireless local area networks applications. Meanwhile, the two-dimensional (2D) radiation patterns and three-dimensional (3D) gain performance of the antenna are also observed and discussed.

• Journal of the Korean Operations Research and Management Science Society
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• v.23 no.3
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• pp.49-62
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• 1998

In the ring loading problem, traffic demands are given for each pair of nodes in an undirected ring network with n nodes and a flow is routed in either of the two directions, clockwise and counter-clockwise. The load of a link is the sum of the flows routed through the link and the objective of the Problem is to minimize the maximum load on the ring. In the ring loading problem with integer demand splitting, each demand can be split between the two directions and the flow routed in each direction is restricted to integers. Recently, Vachani et al. ［INFORMS J. Computing 8 (1996) 235-242］ have developed an Ο(n$^3$) algorithm for solving this integer version of the ring loading problem and independently, Schrijver et al. ［to appear in SIAM J. Disc. Math.］ have presented an algorithm which solves the problem with ｛0,1｝ demands in Ο（n$^2$｜K｜ ) time where K denotes the index set of the origin-desㅇtination pairs of nodes having flow demands. In this paper, we develop an algorithm which solves the problem in Ο(n ｜K｜) time.

• Journal of KIISE:Computer Systems and Theory
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• v.31 no.9
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• pp.487-494
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• 2004

The multiprocessor system suffers interconnection network contension while exploiting the program's parallelism. A CC-NUMA system based on point-to-point link ring structure is one of the scalable architectures that expand the system bandwidth the number of processors/nodes increases. The dual-ring system is a simple solution to enhance the system performance and scalability by duplicating the links. In ring-based systems, an unbalanced transaction among links makes a hot spot on the interconnection network. In this situation, total system performance and scalability are bound by the hot spot of the links In this paper, I propose a dual-link CC-NUMA system, which alleviates the concentration of transactions among the links. By the simulation results, the proposed system significantly outperforms the single-ring and bidirection dual-ring systems. In addition, the proposed system show better distribution of transactions among the links that achieves an extended scalability.

• Management Science and Financial Engineering
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• v.16 no.3
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• pp.85-93
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• 2010

Given an undirected network with a set of source-sink pairs, we are assumed to get a benefit if a pair of source and sink nodes are connected. The k-edge survivability of a network is defined as the total benefit secured after arbitrarily selected k edges are destroyed. The problem of computing k-edge survivability is known to be NP-hard and has applications of evaluating the survivability or vulnerability of a network. In this paper, we consider the k-edge survivability problem restricted to ring networks and develop an algorithm to solve it in O($n^3$|K|) time where n is the number of nodes and K is the set of source-sink pairs.

• Proceedings of the KIEE Conference
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• 2002.07d
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• pp.2344-2346
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• 2002

A vacuum control system has been developed for using Ethernet Multi Serial Device Severs (EMSDS) for the Pohang Accelerator Laboratory (PAL) storage ring. There are 124 vacuum ion pumps at the storage ring. It was a very important problem to solve the problem how to control such a big number of vacuum pumps distributed around the ring. After discussions, we decided to develop a serial to ethernet interrace device sever that will be mounted in the control system rack. It has a 32-bits microprocessor embedded Linux, 12 ports RS485 (or RS232) slave interface. one channel 10/100BaseTx ethernet host port, one channel UART host port, and 16 Mbytes large memory buffer. These vacuum pumps are connected to Ion-Pump serial controllers, which chop the AC current so as to control the current in the pumps. The EMSDS connect either 100BaseTx or 10BaseT ethernet networks to asynchronous serial ports for communication with serial device. It can simultaneously control up to 12 ion-pump serial controllers. 12 EMSDS are connected to a personal computer (PC) through the network. The PC can automatically control the EMSDS by sending a set of commands through the TCP/IP network. Upon receiving a command from a PC running under Windows2000 through the network, the EMSDS communicate through the stave serial interrace ports to ion-pump controller. We added some software components on the top of EPICS (Experimental Physics and Industrial Control System) toolkit.

• Journal of Advanced Navigation Technology
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• v.11 no.4
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• pp.401-407
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• 2007

This paper proposes the ethernet-based in-vehicle networking method for "body" and "multimedia" domains. The ethernet-based in-vehicle networking method should modify the topology and the layer 2 for traffic shaping. In this paper, we simulate the two ring networking systems, the Media Oriented Systems Transport (MOST) and the proposed system with the shaping by the network simulator 2 and evaluate each performance. In addition, we demonstrate the proposed networking system to exchange two kinds of traffic, i.e., QoS data and best-effort data, on the ring network constituting of three nodes. Finally this paper expects to substitute the ethernet-based in-vehicle network for the MOST in advance.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.6B
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• pp.1048-1058
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• 1999

This paper compares some architectures to achieve the optimized WDM architecture for all optical transport network, the comparison is presented in terms of the number of required wavelength and LT. These architecture types are PPWDM, SHWDM, DHWDM and fully optical WDM. Topology is a static ring network where the routing pattern is fixed and traffic pattern has uniform demand. This paper also proposes an algorithm for the wavelength assignment for a folly optical WDM ring network which has full mesh traffic pattern. The algorithm is based on heuristic algorithm which assigns traffic connections according to their respective shortest path. Traffic described here that is to be passed through can be routed directly within the optical layer instead of having the higher layer to handle it.

• KIPS Transactions on Computer and Communication Systems
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• v.8 no.3
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• pp.65-72
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• 2019

HPC(High Performance Computing) is the computing system that connects a number of computing nodes with high performance interconnect network. In the HPC, interconnect network technology is one of the key player to make high performance systems, and mainly, Infiniband or Ethernet are used for interconnect network technology. Nowadays, PCIe interface is main interface within computer system in that host CPU connects high performance peripheral devices through PCIe bridge interface. For connecting between two computing nodes, PCIe Non-Transparent Bridge(NTB) standard can be used, however it basically connects only two hosts with its original standards. To give cost-effective interconnect network interface with PCIe technology, we develop a prototype of interconnect network system with PCIe NTB. In the prototyped system, computing nodes are connected to each other via PCIe NTB interface constructing switchless interconnect network such as ring network. Also, we have implemented prototyped data sharing mechanism on the prototyped interconnect network system. The designed PCIe NTB-based interconnect network system is cost-effective as well as it provides competitive data transferring bandwidth within the interconnect network.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1996.04a
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• pp.87-87
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• 1996

• IEIE Transactions on Smart Processing and Computing
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• v.2 no.2
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• pp.57-66
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• 2013

Wireless Sensor Networks consist of small, inexpensive, low-powered sensor nodes that communicate with each other. To achieve a low communication cost in a resource constrained network, a novel concept of signcryption has been applied for secure communication. Signcryption enables a user to perform a digital signature for providing authenticity and public key encryption for providing message confidentiality simultaneously in a single logical step with a lower cost than that of the sign-then-encrypt approach. Ring signcryption maintains the signer's privacy, which is lacking in normal signcryption schemes. Signcryption can provide confidentiality and authenticity without revealing the user's identity of the ring. This paper presents the security notions and an evaluation of an ID-based ring signcryption scheme for wireless sensor networks. The scheme has been proven to be better than the existing schemes. The proposed scheme was found to be secure against adaptive chosen ciphertext ring attacks (IND-IDRSC-CCA2) and secure against an existential forgery for adaptive chosen message attacks (EF-IDRSC-ACMA). The proposed scheme was found to be more efficient than scheme for Wireless Sensor Networks reported by Qi. et al. based on the running time and energy consumption.