• Journal of the Institute of Electronics Engineers of Korea SD
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• v.48 no.1
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• pp.56-61
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• 2011

This paper describes design of a programmable frequency synthesizer for RF PLL with $0.18{\mu}m$ silicon CMOS technology being used as an application of the UWB system like MBOA. To get good performance of speed and noise super dynamic circuits was used, and to get programmable division ratio switching circuits was used. Especially to solve narrow bandwidth problem of the dynamic circuits load resistance value of unit divider block was varied. Simulation results of the designed circuit shows very fast and wide operation characteristics as 1~14GHz frequency range.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.12
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• pp.1269-1274
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• 2014

Since power and control cables have narrow bandwidth due to their loss at high frequencies, it is difficult to detect the weak fault using conventional reflectometry. It is because the reflected wave caused by the weak fault is overlapped and hidden by the ripple of the strong reflected wave from the end of the cable. This paper proves that the reflected wave from the weak fault can be considered to be linearly superposed on the strong reflected wave from the end of the cable based on the transmission line theory. Then, the weak fault point is experimentally diagnosed using the difference between reflection coefficients before and after the fault generation.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.10
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• pp.1110-1118
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• 2012

In this study, for reducing the residual vibration in high speed motion control stage, an improved 5th order polynomial motion profile was developed. When a stage is moving, the current through the motor coils has the same profile of input motion profile of acceleration, therefore the characteristics of the acceleration input profile directly affect on the performance of the amplifier that includes the current control loop. Commonly low cost amplifier and motor has a narrow current control bandwidth, therefore the proposed algorithm was designed based on this practical constraint. Simulation and experimental results showed that the proposed algorithm clearly has low residual vibration characteristics than conventional 5th order polynomial motion profile on the same drive condition.

• Journal of Advanced Navigation Technology
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• v.6 no.3
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• pp.251-257
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• 2002

Design and characteristic improvement of existing folded dipole antenna is presented to adopt W-CDMA(1.885~2.170 GHz) wideband antenna radiators. The antenna structure has +/- 45 degrees dual polarization. In order to overcome the narrow bandwidth and low gain characteristic typical of the microstrip antenna, double layered structure was employed. The antenna achieved below - 20 dB reflection coefficients each ports, - 20 dB of port isolation, above 7 dBi of gain, providing evidence that the proposed design can be used in the W-CDMA service frequency band antenna.

• The Journal of the Acoustical Society of Korea
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• v.20 no.4
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• pp.17-21
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• 2001

There are some methods to enhance the ‘sweet spot’in loudspeaker-based 3D audio systems. Most of them can be only applied to narrow frequency band inherently. In this paper, we introduce the more robust 3D sound reproduction system which has far wider robust bandwidth. The system applies a sum and difference filter to the conventional three loudspeaker-based one.

• Journal of KIISE:Software and Applications
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• v.30 no.7_8
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• pp.780-791
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• 2003

Caching is a useful technique to improve the response time by reducing contention of requests in mobile computing environments with a narrow bandwidth. in the traditional cache-based systems, to improve the hit ratio has been usually one of main concerns for the time. However, in mobile computing environments, it is necessary to consider the cost of cache miss as well as the hit ratio. In this paper, we propose a new cache replacement strategy in pull-based data dissemination systems. Then, we evaluate performance of the proposed strategy by a simulation approach. The proposed strategy considers both the popularity and the wating time together, so the page with the smallest value of multiplying popularity by waiting time is selected as a victim.

• Journal of Advanced Navigation Technology
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• v.15 no.3
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• pp.355-363
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• 2011

Transcoding in the wireless mobile network is an important mechanism that reduces the delay time and improves the stream processing capacity. Wireless mobile streaming media services, however, have such problems as congestion, interference and delay due to narrow network bandwidth and limited resources. These problems degrade not only Quality of Service (QoS) but also responsiveness of the streaming media service. To solve this problem, this paper proposes a object version transcoding method. The proposed method analyzes the object versions to construct the transcoding graph. This paper utilizes a reference rate-based control function for an efficient streaming, and measures MVDS(Multiple Version Delay Saving) for an efficient delay savings. The simulation results show that the proposed mechanism achieves improved performance in delay rate and cache hit rate compared with those of other existing methods.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1222-1227
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• 2005

In this paper, an efficient scheme of the adaptive notch filter is presented for rejecting the narrow bandwidth interferences(NBI) in GPS receiver. Designed is the lattice IIR double notch filter for more efficient suppression of the NBI with less computational complexity. The algorithm is of recursive prediction error form and uses a special constrained model of IIR with a minimal number of parameters. This paper chooses seven different jamming scenarios including one without jamming for evaluating the proposed filter algorithm. The simulation results to the jamming scenarios show that the proposed algorithm adjusts the double notch filter effectively for the given JSR, and provides better SNR than the conventional algorithms. Finally, it is shown that the advantages of the proposed filter algorithm can range as high as JSR 79dB in time domain processing. Also, the ADNF(adaptive double notch filter) guarantees that more than SNR 10dB of GPS receiver can be always maintained. In conclusion, there is enough evidence to believe that the proposed algorithm will perform quite well for removing interference signals.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.8 no.6
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• pp.73-81
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• 2009

Wireless media communication has lower robustness and stability than wired communication because of narrow bandwidth and unstable channel state. To make up for the deficient points of wireless communication, we used the diversity effect of cooperation communication and the error correction effect of channel coding schemes. In this paper, the cooperative communication system with RCPC codes and Hybrid ARQ transmission scheme is proposed for improving reliability on wireless communication, and we executed these simulations. From the simulation results, proposed system is showed lower BER performance than legacy system. In addition, we confirm the fact that the channel state of Relay-node and source-node is more important than the channel state of Relay-node and destination-node.

• Journal of electromagnetic engineering and science
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• v.2 no.1
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• pp.16-21
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• 2002

On the contrary to the progress of the electronic industry and radio communication technologies, many social problems such as EMI, due to unnecessary electromagnetic(EM) wave are serious with the increased use of EM wave. It is required that the absorbing capability of an EM wave absorber is more than 20 dB, the bandwidth of which is required from 30 MHz to 18 GHz to satisfy the international standard about an anechoic chamber for EMI/EMS measurement$^{[1]}$TEX>. However, the absorbing frequency band of the conventional EM wave absorbers satisfying more than 20 dB is very narrow, for examples, from 30 MHz to 400 MHz in ferrite tile type and from 30 MHz to 870 MHz in ferrite grid type, respectively. In this paper, we proposed and designed a new tripe absorber with broadband characteristics covering the frequency band from 30 MHz to 10 GHz by use of the equivalent material constants method (EMCM)$^{[2]~[4]}$TEX>.