• Journal of the Korea Society for Simulation
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• v.16 no.1
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• pp.1-9
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• 2007

The development of efficient Qualify of Service (QoS) routing algorithms in high speed networks is extremely difficult to achieve, because in order to operate, divergent services require various quality conditions. If the parameter of concern is to measure the delay on a specific link, the routing algorithm obtains the Least Delay (LD) path. Meanwhile, if the parameter is to measure the link cost, the Least Cost (LC) path is calculated. The Delay Constrained Least Cost (DCLC) path problem of the mixed issues on the LD and LC has been shown to be NP-hard. The path cost of LD path is relatively more expensive than that of the LC path, and the path delay of the LC path is relatively higher than that of the LD path in the DCLC problem. In this paper, we introduce the new factor for balancing cost and delay. The simulation result shows that our introduced factor is satisfied to solve the DCLC problem.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.1
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• pp.80-90
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• 1996

The efficienty of ATM is based on the statical multiplexing of fixed-length packets, which are called cells. The most important technical point for realizing ATM switching network is an arrangement of the buffers and switches. Current most ATM switching networks are being achieved by using the switching modules based on the unit switch of $8{\times}8$ 150Mb/s or $16{\times}16$ 150Mb/s, the unit switch of $32{\times}32$150Mb/s for a large scale system is under study in many countries. In this paper, we proposed a new $32{\times}32$(4.9Gb/s throughput) ATM switch using Shared buffer memory switch which provides superior traffic characteristics in the cell loss, delay and throughput performance and easy LSI(Large Scale Integrated circuit). We analytically estimated and simulated by computer the buffer size into it. We also proposed the configuration of the large capacity ATM switching network($M{\times}M$.M>1,000) consisting of multistage to improve the link speed by non-blocking.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.1
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• pp.67-74
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• 2009

In this paper, we investigate the performance limitations of SubCarrier Multiplexed(SCM) WDM systems using optical Double-Side Band(DSB) modulated 16 QAM signals. The Bit-Error Rate(BER) performance is evaluated under various optical transmission links including the effects of the dispersion and fiber nonlinearities such as SPM(Self-Phase Modulation) and XPM(cross-phase modulation). After simulation of SCM-WDM systems, the dominant factors determining the entire system performance are appeared to be the nonlinearity of MZ(Mach-Zehnder) modulator and the SCM channel spacing. The BER performance of subcarrier channels in the higher frequencies was degraded with the large dispersion effect only, however, the performance was improved a little with a combined effect of fiber dispersion and nonlinear effect when the hish fiber launching power was applied.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.11B
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• pp.967-973
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• 2004

DOCSIS and IEEE 802.16 define the usage and element of a MAP which is uplink control message. Standards does not include the details of MAP size and the number of contention slots affecting the performance of MAC protocols for DOCSIS and IEEE 802.16. In this paper, we analyzed the performance of throughput and access delay according to the MAP size and contention slot size. Based on the analytical results, we found the optimal MAP size and the number of contention slots. We found that the protocol shows best performance when the MAP size is 2msec and the number of contention slots is 8. The simulation results can apply to the network system parameters. The simulator can be used to optimize the system parameters in cable network, BWA and WiBro.

• Proceedings of the Korea Contents Association Conference
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• 2006.11a
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• pp.16-20
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• 2006

In Web contents mining, it is important to recognize the unlabeled entities and to integrate the sub-linked information and the extracted results. This paper presents the probabilistic based method which can recognize the unlabeled entity by using the Baysien model. Moreover, we propose the method that can use the information of the sub-linked web pages and integrate the extracted results. In the experimental results, we can see that the probabilistic based entity and information integration show the most significant precision.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.9 s.100
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• pp.855-861
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• 2005

Two-dimensional orthogonal variable spreading codes are presented far multiplexing of forward link in direct sequence code division multiple access(DS-CDMA) multiple antennas system. The bit error rate(BER) performance under a multi-user environment fur the additive white Gaussian noise(AWGN) channel and Rayleigh fading MIMO channel are evaluated. The results demonstrate that the proposed scheme could provide flexible rates and lower peak correlation values.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.16 no.3
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• pp.7-14
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• 2008

In modern aircraft, an autopilot system is getting more important. There are not many autopilot systems applied to small aircraft. Also the autopilot system in large or medium aircraft is difficult to apply to small aircraft directly. It is necessary to make a new autopilot system for small aircraft. In this paper, we implement the small aircraft simulator with autopilot system using SIMULINK. The various modes of autopilot - such as altitude select/hold, attitude hold, heading hold, etc. - are implemented to the flight simulator and tested. We also implement the VOR mode for aircraft guidance.

• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.995-998
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• 1992

A fully software-controlled pulse-width modulatioed (PWM) rectifier with current link is presented. Line power factor is controlled, while maintaining dc current. The input fitter of the PWM rectifier is analyzed and its analysis, shows that unity power factor is achieved with lagging of the input current of the PWM rectifier with respect to the source voltage. The PWM technique is developed using a space vector modulation and is implementation is carried out with a minimal control hardware structure based on one 16-bit single-chip microcomputer. It is shown via experimental results that the proposed sheme gives good performance for the PWM rectifier with current link.

• Journal of the Korean Society for information Management
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• v.16 no.1
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• pp.31-48
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• 1999

This study examined issues of copyright relating to digitization of bibliographic data, copyrighted works, factual data, and manpower's data that the library have. It analyzed issues of copyright relating to the use of digital works and linking. Also It investigated legal issues related information service for user in the library and digital transmission service on need of user out of the library. Finally. this paper proposed basic task for solving issues of copyright in the context of digital libraries.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.1
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• pp.81-87
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• 2007

This paper proposes a new capacitance estimation scheme for a DC-link capacitor in a three-phase AC/DC/AC PWM converter. A controlled AC voltage with a lower frequency than the line frequency is injected into the DC-link voltage, which then causes AC power ripples at the DC side. By extracting the AC voltage and power components on the DC output side using digital filters, the capacitance can then be calculated using the Support Vector Regression (SVR). By training of SVR, a function which relates a given input (capacitor's power) and its corresponding output (capacitance value) can be derived. This function is used to predict outputs for given inputs that are not included in the training set. The proposed method does not require the information of DC-link current and can be simply implemented with only software and no additional hardware. Experimental results confirm that the estimation error is less than 0.16%.