• Journal of Korean Society for Atmospheric Environment
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• v.20 no.4
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• pp.483-491
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• 2004

The purpose of this study is to develop an ozone passive sampler and to evaluate its performance p-Acetamidophenol using as the reagent for ozone reacts specifically with the ambient ozone to produce a fluorescence material (p-acetamidopheonl dimer). The volume of absorbent solution and the extraction time determined at suitable conditions for measuring ozone were 100$\mu$L and 60 min, respectively. The changes of fluorescence were observed with incresing the storage period of passive samplers in ambient air. but the cool storage in a refrigerator did not remarkably influence the increase of fluorescence. The measurement for the precision oi the passive sampling was carried out with duplicate measurement of passive samplers. The intra-class correlation coefficients of passive samplers using dry and wet filters were 0.992 and 0.962, respectively The results from field validation tests indicated practical agreement (dry filter: r=0.963, wet filter: r=0.995) between the passive sampler and an UV photometric $O_3$ analyzer. The limit of quantification of ozone passive samplers with sampling time of 8 hr (wet filter) and 24 hr (dry filter) were 8.0 ppb and 2.7 ppb, respectively.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.58 no.1
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• pp.38-43
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• 2009

Reactors are connected with capacitors to passive filter circuits for reducing harmonics caused by power conversion application. This passive filter frequently gets out of order by voltage and current stress. Especially filter reactor has too much voltage harmonics components, its trouble rate is higher than capacitor. In this paper, we analyzed voltage and current of reactor and capacitor used for passive filter by simulation and measurement. If reactor has a tolerance on variation of reactance value, series resonance frequency is different from originally filter design frequency and parallel resonance can be generated at the close point of the former. Because filter absorbs harmonic component of non-linear load, much of harmonic voltage has been impacted on reactor.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.32B no.12
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• pp.1572-1580
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• 1995

In this paper, a modified Chebyshev low-pass filter function is proposed. The modified Chebyshev filter function exhibits ripples diminishing toward .omega. = 0 in the passband. So, the modified filter function is realizable in the passive doubly-terminated ladder network for the order n even or odd, thus lending itself amenable to active RC or switched capacitor filters through the simulation techniques. Besides the passive doubly-terminated ladder realizability, lower pole-Q values of the modified function are accountable for improved phase and delay characteristics, as compared to classical function. We have designed the 6th order passive doubly-terminated network using the modified function. And then a continuous-time DDA(Differential Difference Amplifier) filter, which has no matching requirement, is realized by leap-frog simulation technique for fabrication. In the HSPICE simulation results, we confirmed that the designed continuous-time DDA filter characteristics are agreement with the passive filter.

• Journal of Power Electronics
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• v.16 no.3
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• pp.1036-1045
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• 2016

This paper presents a novel control strategy for passive output filter reduction using an active output filter. The proposed method achieves the dual-function of regulating the output voltage ripple and output voltage variation during load transients. The novel control strategy allows traditional simple voltage controllers to be used, without requiring the expensive current sensors and complex controllers used in conventional approaches. The proposed method is verified with results from a 125-W forward converter.

• Journal of Power Electronics
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• v.9 no.3
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• pp.403-409
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• 2009

Automatically tuned passive filters can improve power quality to a great extent in power systems. A novel three-phase shunt auto-tuned filter is designed to effectively compensate source current harmonics and to provide reactive power required by the non-linear load, which draws a highly reactive, harmonic-rich current from the supply. An artificial neural network (ANN) based controller selects filter component values in accordance with reactive power requirement and harmonic compensation. Traditional passive filters are permanently connected to the system and draw large amounts of source current even under light load conditions. By using auto-tuned filters, the passive filter components can be controlled according to load variations and, hence, draw only required source currents. The selection is done by the ANN with the help of a properly tuned knowledge base to provide instantaneous compensation using a digital controller.

• KIEE International Transactions on Power Engineering
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• v.4A no.3
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• pp.152-158
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• 2004

The passive filter is economic and efficient in suppressing harmonics but it may cause resonance problems and its performance is constantly dependent on power system impedance or working conditions of loads. This paper presents the DSP (Digital Signal Processor)-based control system, which automatically controls the passive filter in order to solve these problems. The control system can automatically control the passive filter according to working conditions of loads and measured harmonics, reactive power, power factor and so on. Experimental results in the power system using the 100HP DC motor drive are presented in order to verify the performance of the control system.

• KIEE International Transactions on Electrophysics and Applications
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• v.5C no.4
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• pp.176-179
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• 2005

The increasing demand for high density packaging technologies and the evolution to mixed digital and analogue devices has been the con-set of increasing research in thin film multi-layer technologies such as the passive components integration technology. In this paper, Cu and TaO thin film with RF sputtering was deposited for spiral inductor and MOM capacitor on the $SiO_2$/Si(100) substrate. MOM capacitor and spiral inductor were fabricated for L-C band pass filter by sputtering and lift-off. We are analyzed and designed thin films L-C passive components for band pass filter at 900 MHz and 1.8 GHz, important devices for mobile communication system. Based on the high-Q values of passive components, MOM capacitor and spiral inductors for L-C band pass filter, a low insertion loss of L-C passive components can be realized with a minimized chip area. The insertion loss was 3 dB for a 1.8 GHz filter, and 5 dB for a 900 MHz filter. This paper also discusses a analysis and practical design to thin-film L-C band pass filter.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.55 no.6
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• pp.292-298
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• 2006

Because of the high cost for the active power filter, passive filters have been widly used to eliminate harmonic currents of nonlinear load and can also improve the power factor. They are not often optimal filters because the passive filters are designed under the fixed load conditions. In this paper we proposed the method which only the necessary harmonic filters are operated by detecting the various harmonic current components. We presents the new control method of passive filter selection type with the relay control circuit which is consist of analog GIC, comparater, flip-flop and etc. By the experimental results using the proposed system for the rectifier load, we concluded that the researched method is cost effective and the performance is better than the passive filter.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.2
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• pp.82-88
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• 2009

Power capacitor is generally installed to compensate for the low power factor of inductive load But it has been used as passive filter to reduce harmonics generated by the power conversion device. Passive filter is composed by the series connection of reactor and capacitor. Because passive filter has play an important role on the absorber of harmonics, it takes voltage and current stress, follows partially burned on flamed and degradation, finally it has not guaranteed normal life. In this paper, we analyzed the effect that passive filter installed at the source side of PWM inverter is received by harmonics absorption.

• The Journal of the Korea institute of electronic communication sciences
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• v.3 no.4
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• pp.282-288
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• 2008

In this paper, the Passive Intermodulation Distortion(PIMD) of high power RF Filter is measured with filter inner coating materials and we suggest how to reduced the PIMD of RF filter coating methods. According to the standard measurement regulation by IEC, the Passive Intermodulation Distortion of Wibro relay high power filter are measured. We suggest the coating materials and coating methods of high power filter inner structure to reduce the PIMD generating by insert loss and worse flatness of filter delay in the design of Wibro high power filter efficiently.