• Journal of Sensor Science and Technology
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• v.5 no.5
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• pp.63-68
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• 1996

In order to implement the integrated capacitive pressure sensors, which contains integrated interface circuits to detect the electrical output signal, several main factors that have a bad effect on the characteristics of sensors must be improved, such as parasitic capacitance effects, temperature/thermal drift, and the leakage current of a readout circuitry. This paper describes the novel design of the dedicated CMOS readout circuitry that is consists of two capacitance to frequency converters and 4 bit digital logic compensating circuits. Dividing the oscillation frequency of a sensing sensor by that of reference sensor, this circuit is designed to eliminate the thermal/temperature drift and the effect of the leakage currents, and to access a digital signals to obtain a high signal-to-noise(S/N)ratio. Therefore, the resolution of this circuit can be increased by increasing the number of the digital bits. Digital compensated circuits of this circuits, except for the C-F converters, are fabricated on a FPGA chip, and fundamental performance of the circuits are evaluated.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.10
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• pp.74-81
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• 2006

This paper proposes the sensorless vector control scheme of a Non-salient permanent-magnet synchronous motor (SPMSM) using programmable low pass filter (PLPF) to estimate a stator flux with the information of a rotor position and speed. The sesorless vector control of PMSM using PLPF can solves the dc drift problem associated with a pure integrator and a LPF. Also, the PLPF has the phase and gain compensator to estimate exactly rotor position and speed. Therefore, the information of a position and speed is exactly estimated because the drift and offset problems are solved by the PLPF. The experimental results show good performance over the 10[%] of the rated speed and under load condition.

• Korean Journal of Optics and Photonics
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• v.16 no.4
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• pp.319-325
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• 2005

A signal processing method for white light interferometry (WLI), which performs a series of analog signal processing steps to locate the central interference fringe position at high speed: is developed and applied to a WLI temperature sensor system. We found that the new method has random walk of $0.019^{\circ}C/\sqrt{Hz}$ with good linearity. However, the temperature change in the path-matching interferometer results in drift of the measured sensor output. The temperature dependence of drift in the WLI temperature sensor system, was calculated to be $1.42{\mu}m/^{\circ}C$. It is also found that the relationship between the peak spacing in the interferogram and the spacing measured by the method can be nonlinear when the fringe spacing is comparable to the coherence length of the source.

• The Transactions of the Korean Institute of Power Electronics
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• v.3 no.2
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• pp.125-130
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• 1998

This paper describes a novel flux calculator for the estimation of real rotor flux angle which is indispensable to the field oriented control of induction motors. A pure integrator is used to estimate the real rotor flux precisely from voltage and current information. The proposed flux calculator adopts the new drift compensation method to overcome the drift problem of pure integrator. The motor speed is calculated using estimated flux angle and estimated slip frequency. The performance of this approach is verified through the experiment. The experimental results shows stable operation of proposed system even below 1/100 of rated speed.

• Proceedings of the KIEE Conference
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• 2005.10b
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• pp.130-132
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• 2005

This paper presents two ART-based neural networks for the identification of gas mixtures subject to the drift. A fuzzy ARTMAP neural network is used for classifying $H_2S$, $NH_3$ and their mixture gases including a reference gas. The other fuzzy ART neural network is utilized to detect the drift of a tin oxide gas sensor by tracking a cluster center of the reference gas. After detecting the drift, the previous cluster center of each gas is updated as much as the drift of the reference gas. By the simulations, the proposed method is shown to compensate the drift on-line without making many categories of target gases compared with the previous studies.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.3A
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• pp.237-246
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• 2007

Clock Synchronization is one of the most basic factors to be considered when we implement an indoor synchronization network for indoor positioning. In this paper, we present a new synchronization algorithm which does not employ time stamps in order to reduce the hardware complexity and data overhead. In addition to that, we describe an algorithm that is designed to compensate the frequency drift giving an serious impact on the synchronization performance. The performance evaluation of the proposed algorithm is achieved by investigating MTIE (Maximum Time Interval Error) values through simulations. In the simulations, the frequency drift values of the practical oscillators are used. From the simulation results, it is investigated that we can achieve the synchronization performance under 10 ns when we use 1 second synchronization interval with 1 ns resolution and TCXOs (Tmperature Compensated Cristal Oscillators) both in the master clock and the slave clock.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.28 no.2
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• pp.311-326
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• 2018

This paper has experimented using News sample video with QCIF ($176{\times}144$) resolution in JM v10.2 code of H.264/AVC-MPEG. The region of interest (ROI) to be encrypted occurred the drift by unnecessarily referring to each frame continuously in accordance with the characteristics of the motion prediction and compensation of the H.264 standard. In order to mitigate the drift, the latest related research method of re-inserting encrypted I-picture into a certain period leads to an increase in the amount of additional computation that becomes the factor increasing the bit-rate overhead of the entire video. Therefore, the reference search range of the block and the frame in the ROI to be encrypted is restricted in the motion prediction and compensation for each frame, and the reference search range in the non-ROI not to be encrypted is not restricted to maintain the normal encoding efficiency. In this way, after encoding the video with restricted reference search range, this article proposes a method of RC4 bit-stream encryption for the ROI such as the face to be able to identify in order to protect personal information in the video. Also, it is compared and analyzed the experimental results after implementing the unencrypted original video, the latest related research method, and the proposed method in the condition of the same environment. In contrast to the latest related research method, the bit-rate overhead of the proposed method is 2.35% higher than that of the original video and 14.93% lower than that of the latest related method, while mitigating temporal drift through the proposed method. These improved results have verified by experiments of this study.

• Journal of Broadcast Engineering
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• v.6 no.2
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• pp.121-130
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• 2001

We propose an efficient DCT-domain video transcoding algorithm for flexible for bit-rate video communications. Video transcoding provides communication fiexibility by adaptively changing the bit-rate of compressed bit stream. During the transcoding process, adrift error is unavoidable because of the difference between reference images in the series of encoding and decoding. For solving the drift error problem, cascade pixel-domain transcoder (CPDT) has been proposed. CPDT, however, requires highly complex hardware and heavy computational overhead. In this paper we propose a DCT-domain transcoding technique, which enables efficient transcoding without any drift error. The proposed cascade DCT-domain transcoder (CDDT) is realized by new motion compensation and down-sampling methods in the DCT-domain.