• Journal of the Korea Society of Computer and Information
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• v.7 no.2
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• pp.101-114
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• 2002

The real multimedia application in wide area communication needs the guaranteed performance of communication service. Therefore, the resource is reserved at the moment of traffic burst and the region of connection admission possibility is widened at the basis of maximum cell rate. This of study shows that the end-to-end traffic delay to the traffic of burst state is guaranteed when the total of maximum transmission rate is higher than link speed by using the region of deterministic delay. The network load rate of connection admission can be improved by the inducement of delay bounds consideration each traffic characteristic to guarantee the end-to-end delay of network from single switch. This suggested buffering system using deterministic service do not give any influence to service quality and can guarantee the bounds of end-to-end delay. And it can also reduce the load of network even if the delay is increased according to the burst traffic characteristic. The above suggested system can be applied effectively to the various kinds of general network specification which admit both real time trafnc service and non-real time traffic service.

• Journal of the Korea Society of Computer and Information
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• v.8 no.2
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• pp.97-105
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• 2003

This thesis proposes a new type of Input-Output Buffered ATM Switch which employs an arbiter and its performance under different traffic conditions studied. The proposed switch is designed with a view to exploit the architecture and other characteristics of the arbiter The primary aim of the proposed switch is the elimination, or at least, the reduction of HOL blocking phenomenon which occurs in the simple input buffered switch. Several HOL arbitration algorithms have been proposed for this purpose in the literature. The Proposed switch attempts to reduce the HOL blocking as it uses the arbiter and the buffer at the output Port in an effective manner. The arbiter is designed to work with Three Phase Algorithm which is one of the many well known HOL arbitration algorithms . The proposed switch acquires control over priority transmission through the REd signal. As the signals are transmitted to the arbiter, the latter controls the one which is sent by the input buffer. Computer simulation results have been provided to demonstrate the effectiveness of the proposed switch under non-uniform random traffic conditions.

• The Journal of the Korea institute of electronic communication sciences
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• v.10 no.12
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• pp.1315-1320
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• 2015

In this paper Communication data link equipment on a high speed-hopping method to use the frequency resources efficiently for the frequency environment is introduced such as sensing techniques, using the same frequency band by using the received two-channel technique and the receive filter bank unit applied to be shared with other equipment such as radar and so on. The real-time measurement and analysis were operated for measurement the frequency environment of the operating band in advance. and primarily equipment to develop is analyzed how the interference effect to the radar minimize the operation of radar equipment. In reverse, to use the same frequency band the methods such as frequency sharing techniques are presented in this paper. Finally, by design of the main items of the RF transceiver NF, transmission output, and a simulation of the IMD, such as whether the key is verified prior to meet specifications.

• Journal of Digital Convergence
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• v.12 no.3
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• pp.249-254
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• 2014

Wireless LAN system is evolving toward high-speed data transmission and more accurate channel estimation is necessarily required to improve communication performance. The PLCP preamble field in IEEE 802.11 based wireless MODEM consists of ten short symbols and two long symbols and is used for synchronization and channel estimation. The existing least square (LS) channel estimation is based on only two long training symbols. After estimating channel response separately by using each long training symbol, the final channel estimation is obtained by the average of each estimation. In this paper, a new channel estimation algorithm is presented to improve the performance of the existing LS channel estimation algorithm. From the fact that the short training symbol consists of 12 non-zero subcarriers, it gives us a clue of being able to additionally estimate at least one fourth of channel coefficients. The new LS algorithm performs channel estimation based on both two long training symbols and a short training symbol. The proposed LS algorithm shows a little bit performance improvement over the existing LS estimation and it will be able to be applied to the IEEE 802.11p WAVE system.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.39 no.9
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• pp.19-27
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• 2002

Characteristics of interconnect lines considering underlayer geometries of a silicon substrate and crossing metal lines are experimentally analyzed through elaborately devised patterns. In this work, test patterns for transmission lines having several kinds of underlayer geometries were devised, and the signal characteristics and responses are measured by S-parameter and time domain reflection meter (TDR). The patterns were designed and fabricated with a deep-submicron CMOS DRAM technology having 1 Tungsten and 2 Aluminum metals. From the analysis of measured results on the patterns, it is founded that the effects of underlayter line structures on line parameters (especially line capacitance and resistance) and signal distortions occurred from them cannot be negligible. The results provide useful and insightful understanding in the skew balance of package leads and global signal lines such as high-speed clock and data lines.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.12B
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• pp.1066-1074
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• 2008

In this paper, we proposed an efficient algorithm using pulse signal based on group-node-contention in LR-WPAN. The purpose of IEEE 802.15.4 is low speed, low cost and low power consumption. Recently, as applications of LR-WPAN have been extended, there is a strong probability of collision as well and almost collision occurs because of hidden node problem. Moreover, if the collision continuously occurs due to hidden node collision, network performance could be decreased. Nowadays, although several papers focus on the hidden node collision, algorithms waste the channel resource if continuous collisions frequently occur. In this paper, we assume that PAN has been already formed groups, and by using pulse signal, coordinator allocates channel and orders, and then, nodes in the allocated group can compete each other. Hence, contention nodes are reduced significantly, channel wastage caused by collision is decreased, and data transmission rate is improving. Finally, this algorithm can protect the network from disruption caused by frequent collisions. Simulation shows that this algorithm can improve the performance.

• The Journal of the Korea institute of electronic communication sciences
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• v.6 no.3
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• pp.381-387
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• 2011

Measurement controller that acquire and control and observe data from scattering sensors is organic with central control room. Therefore, measurement controller is efficient wireless network than wire network. But, serious problem is happened in security from outside if use wireless network. Therefore, this paper proposed suitable MS-WP cryptographic system to measurement control wireless network to augment network efficiency of measure controller. Result that implement proposed MS-WP cryptographic system by chip level and achieve a simulation, confirmed that 130% processing rate increase and system efficiency are increased double than AES algorithm. Proposed MS-WP cryptographic system augments security and is considered is suitable to measurement controller because that low power is possible and the processing speed is fast.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.4 no.4
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• pp.286-294
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• 2011

Cable modems typically are implemented by a forward error correction(FEC) scheme. The ITU-T Recommendation J-38 Annex B specifies using 64- and 256- quadrature amplitude modulation (QAM) and extended RS coding scheme. In implementing the cable modem, there are some problems to fabricate and fitting on FPGA chip. First, many clocks are needed in implementing cable modem because of different code rate and different modulation types. To reduce the number of clocks, we use the two memories, which are different clock speed for reading and writing data. Second, this system lost the bit-synchronization and frame-synchronization in decoder, the system recognize that all data is error. This paper solves the problems by using simple 5-stage registers and unique sync-word. Based on solutions for about problems, the cable modem is fabricated on FPGA chip name as Vertex II pro xc2vp30-5 by Xilinx, and we confirmed the effectiveness of the results.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.12B
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• pp.1081-1090
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• 2003

NGI(Next Generation Internet) is characterized by QoS(Quality of Service) and high speed transmission. Recently, DiffServ and MPLS become most influential NGI architecture. To guarantee end-to-end QoS, it is essential for NGI to interwork MPLS with DiffServ. Here, MPLS WG(Working Group) in IETF(Internet Engineering Task Force) proposed the method of E-LSP(EXP inferred-PSC LSPs) and L-LSP(Label-Only-Inferred PSC LSPs), but both of them have serious problems to satisfy perfect interworking. In this paper, we proposed an extended E-LSP architecture that supports Perfect DiffServ class and experimental function in MPLS such as ECN(Explicit Congestion Notification) capability. We verify that the proposed E-LSP architecture improves QoS in NGI by using ns2 simulator.

• International Journal of Automotive Technology
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• v.6 no.2
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• pp.149-159
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• 2005

A full nonlinear finite element P185/70Rl4 passenger car radial-ply tire model was developed and run on a 1.7-meter-diameter spinning test drum/cleat model at a constant speed of 50 km/h in order to investigate the tire transient response characteristics, i.e. the tire in-plane free vibration modes transmissibility. The virtual tire/drum finite element model was constructed and tested using the nonlinear finite element analysis software, PAM-SHOCK, a nonlinear finite element analysis code. The tire model was constructed in extreme detail with three-dimensional solid, layered membrane, and beam finite elements, incorporating over 18,000 nodes and 24 different types of materials. The reaction forces of the tire axle in vertical (Z axis) and longitudinal (X axis) directions were recorded when the tire rolled over a cleat on the drum, and then the FFT algorithm was applied to examine the transient response information in the frequency domain. The result showed that this PI 85/70Rl4 tire has clear peaks of 84 and 45 Hz transmissibility in the vertical and longitudinal directions. This result was validated against more than 10 previous studies by either theoretical or experimental approaches and showed excellent agreement. The tire's post-impact response was also investigated to verify the numerical convergence and computational stability of this FEA tire model and simulation strategy, the extraordinarily stable scenario was confirmed. The tire in-plane free vibration modes transmissibility was successfully detected. This approach was never before attempted in investigations of tire in-plane free vibration modes transmission phenomena; this work is believed to be the first of its kind.