• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.6
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• pp.1025-1031
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• 2006

In this paper, a deconvolution filtering method for all-pass systems based on FIR approximation is proposed. The proposed method enables us to obtain a causal stable deconvolution filter by FIR approximating a non-causal stable deconvolution filter to a causal stable one. As we can see in this paper, the impulse response of the deconvolution filter for all-pass system is simply the mirror image of the impulse response for all-pass system itself. Due to this symmetric property between all-pass system itself and its deconvolution Inter, this method can be applied to all-pass systems without special limitation of the system's order. In order to verify the performance of the proposed method. computer simulation results for 1st-, 2nd- and 400th-order all-pass systems are included.

• Journal of the Institute of Convergence Signal Processing
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• v.5 no.2
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• pp.151-158
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• 2004

In this paper, an inverse filtering technique for the digital filter model is proposed. This technique enables us to obtain a stable non-causal m inverse filter by transforming (approximating) it to a causal stable inverse system. In practice, a causal FIR approximation to this inverse filter is proposed. It can be shown that the impulse response of the inverse filter for all-pass systems is simply the mirror image of the impulse response for the system. Specially, due to this symmetric property of the impulse response of all-pass systems, the proposed technique is more useful for all-pass systems than other systems. In order to illustrate the proposed inverse filtering technique, four examples are presented. Two of them are for all-pass filters. The other two examples are for IIR and FIR filters. Also, computer simulations demonstrate that the proposed technique works very well.

• Proceedings of the KSR Conference
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• 2001.10a
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• pp.62-73
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• 2001

The scope of this study is focused on the survey of new logistics transportation systems in railroad and case studies of new systems such as piggyback system, bi-modal system swapbody, and double stack train(DST). Piggyback system, bi-modal system, swapbody, and double stack train are reviewed in term of technological validity and economic validity in Korea. Piggyback - trailer does pass loaded weight limits but does not pass train limits and can not utilize the existing freight cars. Piggyback - cargo trunk does pass all the criteria and could be developed by a domestic technology. But this study suggests to expand the length of train cars to 18.300mm for accommodation of two cargo trucks. Bi-modal system and swapbody do also pass. Double stack train could only pass the loaded weights and does not meet the train limit and the possibility of using existing freight cars. Domestic technology could not development DST, due to civil engineering construction limits and low standard height of electric line, which could not afford to operate DST.

• Proceedings of the KIEE Conference
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• 1987.07b
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• pp.850-853
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• 1987

A VLSI digital filter design using a semi-custom method is described. The digital filters composed of TDM/FDM Transmultiplexer are designed. Using the polyphase network approach a filter bank composed of only all-pass digital filter sections was designed. The use of all-pass filters as basic building blocks is shown to provide a transmultiplexer structure that has low computational requirements, low quantization noise, and high modularity. The silicon compiler systems is used to reduce the design time and increase the credibility of designed filters. A design of 1st order and 2nd order all pass filters is done using CMOS 2um N-well double metal cell.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.13 no.1
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• pp.86-98
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• 2014

Currently, many OBUs(On Board Unit)s were installed on the vehicle because ETCS(Electronic Toll Collection System) using DSRC(Dedicated Short Range Communication) was constructed in the tollgate of the whole country.A research development and the commercialization utilizing the One Card All Pass and those Infrastructures of ETCS, are promoting of ITS services. Although many studies of the application method about the One Card All Pass of ETCS have been made, standards about the application method of the One Card All Pass and payment for the provision of traffic convenience, were not made clear. So we are proposed method that One Card All Pass announced by Ministry of Land, Infrastructure and Transport, takes advantage of the existing DSRC-based to apply ETCS. We have confirmed the performance of the system through a variety of driving test using three test vehicles on trial operation site and ETCS applying application method proposed in this study. As a result of driving test, we have confirmed validity of standard application method proposed in this study through the communication success rate of about 99% and analyzed problem that may occur by applying service parts of ETCS of transportation convenience facilities because of about 1% communication failure rate.

• Journal of Korea Society of Industrial Information Systems
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• v.19 no.2
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• pp.45-49
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• 2014

In this work, a phase shifter radio-frequency integrated chip (RFIC) using a simple all-pass network is presented. As a tuning element of the phase shifter RFIC, tunable capacitors with a multi-layer dielectric of a para-/ferro-/para-electrics using a high tunable BST ferroelectric and a low-loss BZN paraelectric thin film were utilized. In order to evaluate and analyze the fabricated phase shifter RFIC, the same elements such as an inductor and capacitor integrated into it are also fabricated and tested. The designed phase shifter RFIC was fabricated on a quartz substrate in the size of $1.16{\times}1.21mm^2$. As the test results, the maximum phase difference of $350^{\circ}$ is obtained at 15 V and its tuning frequency bandwidth is 90 MHz from 2.72 to 2.81GHz.

• Journal of Institute of Control, Robotics and Systems
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• v.4 no.2
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• pp.170-177
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• 1998

In this paper, a unified solution of Hankel norm approximation problem is proposed by $\delta$-operator. To derive the main result, all-pass property is derived from the inner and co-inner property in the $\delta$-domain. The solution of all-pass becomes an optimal Hankel norm approximation problem in .delta.-domain through LLFT(Low Linear Fractional Transformation) inserting feedback term $\phi(\gamma)$, which is a free design parameter, to hold the error bound desired against the variance between the original model and the solution of Hankel norm approximation problem. The proposed solution does not only cover continuous and discrete ones depending on sampling interval but also plays a key role in robust control and model reduction problem. The verification of the proposed solution is exemplified via simulation for the zero-order Hankel norm approximation problem and the model reduction problem applied to a 16th order MIMO system.

• JSTS:Journal of Semiconductor Technology and Science
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• v.16 no.3
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• pp.312-318
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• 2016

This paper presents a 2-6 GHz GaN HEMT power amplifier monolithic microwave integrated circuit (MMIC) with bridged-T all-pass filters and output-reactance-compensation shorted stubs using the $0.25{\mu}m$ GaN HEMT foundry process that is developed by WIN Semiconductors, Inc. The bridged-T filter is modified to mitigate the bandwidth degradation of impedance matching due to the inherent channel resistance of the transistor, and the shorted stub with a bypass capacitor minimizes the output reactance of the transistor to ease wideband load impedance matching for maximum output power. The fabricated power amplifier MMIC shows a flat linear gain of 20 dB or more, an average output power of 40.1 dBm and a power-added efficiency of 19-26 % in 2 to 6 GHz, which is very useful in applications such as communication jammers and electronic warfare systems.

• Journal of information and communication convergence engineering
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• v.4 no.4
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• pp.166-169
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• 2006

Almost all network systems provide an authentication mechanism based on user ID and password. In such system, it is easy to obtain the user password using a sniffer program with illegal eavesdropping. The one-time password and challenge-response method are useful authentication schemes that protect the user passwords against eavesdropping. In client/server environments, the one-time password scheme using time is especially useful because it solves the synchronization problem. In this paper, we present a new identification scheme: OPI(One Pass Identification). The security of OPI is based on the square root problem, and OPI is secure: against the well known attacks including pre-play attack, off-line dictionary attack and server comprise. A number of pass of OPI is one, and OPI processes the password and does not need the key. We think that OPI is excellent for the consuming time to verify the prover.

• Journal of international Conference on Electrical Machines and Systems
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• v.2 no.4
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• pp.447-453
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• 2013

Compensating characteristics of a voltage sag/swell compensator utilizing single-phase matrix converter is examined. First, system configuration and operation for both voltage sag and swell are described. Next, in order to suppress pulsations of the source voltage, a countermeasure using low pass filter and all pass filter is introduced. Then, compensating characteristics of the compensator are investigated for R-L load by simulation. Finally, the validity of the simulated results is confirmed by the experimental results.