• The Transactions of the Korean Institute of Electrical Engineers P
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• v.59 no.1
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• pp.64-70
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• 2010

This paper presents how to decide on tuning factor(${\delta}$) and quality factor(Q) values in design of single-tuned passive harmonic filters. Tuning factor(${\delta}$) and quality factor(Q) values have to consider before decision on circuit parameters of passive filters. A Study on these two value has not been scarcely performed and only experienced values has been used in passive harmonic filter design by far. As a experienced value, in cases of 5th and 7th filter, tuning factor(${\delta}$) is about 0.94 and 0.96 respectively and quality factor(Q) is, in all cases of, 50. If Single-tuned passive harmonic filter will be off-tuned, performance of filter will be decreased steeply and occur to parallel resonance between system reactance and filter capacitance. Therefore During the operation, In order not to off-tuning, Filter must be tuned at former order than actual tuning order. This is the same that total impedance of filter must have a reactive impedance. In this paper, Tuning factor(${\delta}$) is decided via example of real system and using the bode-plot and then performance of filters confirmed by filter current absorbtion rate. And Quality factor(Q) decided using the bode plot in example system and then performance of filters confirmed by filter current absorbtion rate also, which makes a calculated filter parameters to satisfy IEEE-519 distortion limits. Finally, Performance of the designed passive harmonic filter using the tuning factor(${\delta}$) and quality factor(Q) values, decided in this paper is verified by experiment and shows that 5th, 7th, 9th, 11th and 13th current harmonic distortions are decreased within IEEE-519 distortion limits, respectively.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.32-35
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• 1996

In this paper, it is shown that the dominant errors of baro-altimeters can be characterized by bias and scale factor errors. Also an optimal filter for estimating both bias and scale factor is derived based on the concept of model transition. The optimal filter is, however, not realizable because the model transition hypotheses increase exponentially. Therefore a realizable suboptimal filter using the interacting multiple model(IMM) technique is proposed. Computer simulation results show that the estimation errors of the proposed filter are smaller than those of the conventional least squares algorithm with a forgetting factor when both the bias and the scale factor are varying.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.4
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• pp.716-723
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• 2007

This paper suggests of a 3-phase 3-wire unified active power filter. The system is composed of a series active power filter and a parallel active power filter. The proposed series active power filter compensating unbalance source voltage and current harmonics of the parallel active power filter improves power factor. The proposed algorithm which improves for power factor and harmonic reduction are calculated by the performance function, and which compensates for the unbalanced source voltage is calculated based on the symmetrical component analysis. We composed a combined system of the series active power filter and parallel active power filter to confirm a validity of the proposed control methods. The effectiveness of the proposed algorithm is confirmed by the experiments.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.53 no.1
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• pp.24-29
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• 2004

A new low cost hybrid active filter for thyristor-controlled rectifier load is presented to overcome the high cost problem of the active or the other hybrid active filters. The proposed hybrid active filter which consists of tuned (5th and 7th harmonics) LC passive filters, power factor improvement(PFI) capacitor bank, and active filter compensates power factor as well as harmonic currents. Since most of harmonic currents are filtered by the passive filter and most of reactive power is compensated by the PFI capacitor bank, the power rating of active filter can be minimized, resulting in cost minimization of the proposed hybrid active filter. A 300kVA hybrid active filter system is implemented and tested using 1MVA thyristor rectifier load to verify the operation and performance.

• Journal of Industrial Technology
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• v.25 no.B
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• pp.195-202
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• 2005

The rectifier characteristics and the quality of the input current worsens with the increase of unbalances or harmonics of the supply voltages. Rectifier input current harmonics interfere with proper power system operation, reduce rectifier power factor, and limit the power available from a given source. It is of importance to select appropriately the rectifier's output filter inductance to determine the rectifier input current waveform, the input current harmonics, and the power factor. This paper presents a quantitative analysis of single and three phase rectifier input current harmonics, total harmonic distortion, and power factor as a function of the output filter inductance under balanced and unbalanced conditions. Also, its performance under the supply voltage including harmonics be investigated. These results provide a reference for selecting reasonable rectifier's output filter inductance for given harmonics or power factor criterion.

• Journal of Korea Society of Digital Industry and Information Management
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• v.11 no.1
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• pp.171-182
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• 2015

The general wavelet transform has profitable property in non-stationary signal analysis specially. The tunable Q-factor wavelet transform is a fully-discrete wavelet transform for which the Q-factor Q and the asymptotic redundancy r, of the transform are easily and independently specified. In particular, the specified parameters Q and r can be real-valued. Therefore, by tuning Q, the oscillatory behavior of the wavelet can be chosen to match the oscillatory behavior of the signal of interest, so as to enhance the sparsity of a sparse signal representation. The TQWT is well suited to fast algorithms for sparsity-based inverse problems because it is a Parseval frame, easily invertible, and can be efficiently implemented. The transform is based on a real valued scaling factor and is implemented using a perfect reconstruction over-sampled filter bank with real-valued sampling factors. The transform is parameterized by its Q-factor and its over-sampling rate, with modest over-sampling rates being sufficient for the analysis/synthesis functions to be well localized. This paper describes filter design of 2D discrete-time wavelet transform for which the Q-factor is easily specified. With the advantage of this transform, perfect reconstruction filter design and implementation for performance improvement are focused in this paper. Hence, the 2D transform can be tuned according to the oscillatory behavior of the image signal to which it is applied. Therefore, application for performance improvement in multimedia communication field was evaluated.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.10 no.1
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• pp.170-178
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• 2000

Most of manufacturers try to produce the most efficient filter for respirators with the lowest breathing resistance. Filter performance depends on low penetration, i.e., high efficiency (%), and low pressure drop ($mmH_2O$). This study was performed to evaluate performance of respirator filters by quality factor ($q_F$) and suggest the direction for improvement of respirator filters of good quality in Korea. Two mechanical filters, S and K made in Korea, three filtering facepieces, S made in China, C made in Korea and M made in USA, which were widely used in the workplace, were selected and tested efficiency and pressure drop in accordance with flow rate, using with Automated Filter Tester Model 8110 (TSI, USA). The best quality factor within the same respirator filter categories was $0.0672cm^{-1}\;H_2O$ for mechanical filter S, $0.0698cm^{-1}\;H_2O$ for filtering facepiece M at flow rate of 32Lpm. Mechanical filter S would be the best suitable during heavy work since qulity factors decrease less sharply than any others as increased flow rates. It was necessary for mechanical filter S to lower pressure drop without increasing efficiency, but mechanical filter K should be increased efficiency and decreased pressure drop. While filtering facepiece M had the best quality performance of three ones, Sand C should get much higher efficiency and lower pressure for better performance.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.12C
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• pp.1280-1287
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• 2006

We propose a modified stochastic gradient-based (MSGB) filter showing that the filter is the solution to an optimization problem. This paper analyzes the properties of the MSGB filter that corresponds to the nonlinear adaptive filter with additional update terms, parameterized by the variable scaling factor. The variably parameterized MSGB filter plays a role iii connecting the fixed parameterized MSGB filter and the null parameterized MSGB filter through variably scaling parameter. The stability regions and misadjustments are shown. A system identification is utilized to perform the computer simulation and demonstrate the improved performance feature of the MSGB filter.

• Journal of the Korean Institute of Telematics and Electronics
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• v.4 no.1
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• pp.13-21
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• 1967

A low pass filter is synthesized with R, C and negative impedance converters(NIC). The filter has a 4-th order elliptic function, which gives best magnitude approximation with equi-ripple characteristics both in pass and stop band. And experimental investigations have been made on the effect of the anticipated deviation of the NIC conversion factor and of possible loaded operation. Through the study, it has been cocluded that: 1. For minimum pole-zero sensitivity with respect to the NIC conversion factor, the network of a parallel RC-NIC configuration is preferable and the Horowitz polynomial decomposition method is applied in the synthesis procedure. 2. A few percentage variation of the NIC conversion factor changes the frequency and amplitude characteristics of the filter by nearly negligible amount. 3. With a load resistance below the critical value, the filter turns into an oscillator.

• Journal of the Korean Society of Tobacco Science
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• v.27 no.2
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• pp.163-170
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• 2005

A theoretical model for predicting the capability curve of cellulose acetate filter is derived. The pressure drop is expressed as a function of the filter dimensions, the tow fiber characteristics, the filter weight, the fluid flow rate, and a filter fiber factor. Where, the filter fiber factor is affected by the distribution of the tow fibers within the filter, the relative orientations of the tow fibers, and their cross-sectional shapes. The minimum and maximum fraction of solids in capability curves determined from experimental data. Also, the filter fiber factor is expressed as a function of the filter length, tow fiber length, and tow fiber diameter. Capability curves predicted by the suggested model in this work correspond well with capability curves by experimental data.