• Proceedings of the KIPE Conference
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• 1997.07a
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• pp.193-199
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• 1997

Until now, environmental problem has become more and more serious, and acoustic noise is one of environmental pollutions. For many years, ANC(Active Noise Control) has been made to reduce this noise. In this paper, active silencer using switching method is studied. This silencer is composed of single-phase full bridge inverter to drive cancelling loudspeaker. The inverter is controlled to reduce noise by ramp comparison control method. At the vacuum cleaner, noise control with FFCS(Feed-Forward Control Structure) is applied and geometric arrangement is replaced to avoid unstability of FFCS.

• Proceedings of the KIEE Conference
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• 1995.07a
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• pp.311-314
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• 1995

PWM(Pulse-Width Modulation) is frequently used as control method for inverter. In control of active silencer studied presently, PWM control method can be applied. This paper presents its possibility. As operating source of loudspeaker, inverter is used instead of audio amplifier and PWM controller controls the inverter to make canceling sound. This paper presents that active silencer of inverter-type using the PWM control method makes the canceling sound to acoustic noise and cancels the acoustic noise.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.443-446
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• 1996

This paper presents active silencer by Switched-scheme. Full-bridge inverter to used as operating source of loudspeaker for proposed scheme. And ramp comparison control and hysteresis control are used respectively for active noise control method in this scheme. Computer simulation is accomplished to show the noise reduction characteristics by Switched-scheme. The results of experiment present the effect of audible noise reduction.

• Proceedings of the KIPE Conference
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• 1996.06a
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• pp.93-98
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• 1996

This paper presents active silencer by hysteresis control method using DSP-scheme and shows it audible noise reduction effect. Pentium processor and sound blaster 16 are used for its implementation. The sound blaster 16 executes A/D, D/A conversion and is used operating source of loudspeaker for cancelling.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.858-861
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• 2006

In this paper, a study on the noise reduction in a mobile fuel cell system is presented. Among various fuel cell systems around 20W capacities designed for mobile electronic devices, the active direct methanol fuel cell (DMFC) systems have been recently developed. In such systems, the primary noise source is the air pump which provides sufficient air flow ($5{\sim}6$ liter/min) for electrochemical reaction with methanol fuel while the noise contributions from other auxiliary parts are relatively small. Especially, the discrete noise tones generated by the air pump are dominant and those frequency peaks related to the rotor harmonics are needed to be suppressed by a silencer. Therefore. the Herschel/Quinke (HQ) tubes, which use the out-of-phase cancellation of acoustic waves propagating through direct and indirect pathways, are applied to the inlet of the air pump. Performance of noise reduction with HQ silencer is analytically estimated by calculating the transmission. The length and number of thin HQ tubes are optimized to decrease the radiated noise. As a result, the sound pressure level could be successfully reduced by about 10 dB after applying three serially connected HQ tubes.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.34S no.7
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• pp.112-122
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• 1997

This paper presents active silencing by hysteresis control method and shows its audible noise reduction effect. A Pentium processor and sound blaster 16 card are used for its implementation. The Sound-Blaster 16 executes the A/D, D/A conversion and is used for operating source of lodspeaker for cancelling. As a result, between the frequency range of 100[Hz] and 200[Hz] there is an audible noise reduction effect from 9[dB] to 15[dB], and between the 300[Hz] and 500[Hz] range there is a reduction from 3[dB] to 5[dB].

• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.692-694
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• 1993

Acoustic noise from the various facilities makes man unpleasant and let researchers find the way for reducing it on environmental point of view. Special way to reduce the acoustic noise had suggested by the concept of Active Silencer. But, it has propagation delay time accumulated during the signal passage and howling effect. This paper suggestes a way to anhilate howling effects, and reduces the total delay time drasticaly by attaching microphone to the speaker. This paper will show how it works by some materials.

• The Transactions of the Korean Institute of Power Electronics
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• v.2 no.2
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• pp.35-40
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• 1997

The hysteresis control method has been frequently used for current control of power conversion equipments or motor drive systems. This method makes the measured signal follow the reference signal by changing the control signal whenever the error signal exceeds the preset band width. In this paper, hysteresis control method with fast response characteristics is applied for active noise control to suppress acoustic noise. Both Pentium processor and sound blaster 16 are used for experimental implementation, which executes A/D, D/A conversion and also is used as operating source of loudspeaker for audible noise cancellation.