• Proceedings of the IEEK Conference
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• 2000.06b
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• pp.197-200
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• 2000

This paper proposes a CMOS low noise VGA. It describes the noise optimization method of the proposed VGA. The designed VGA provides of a 0 to 21.30dB gain variation and its bandwidth of 49MHz. The input reflected noise voltage is 4.84nV/sqrt-hz at 1MHz and noise figure is 14.53dB(Rs=50 Ω). The VGA was fabricated using a 0.35-${\mu}{\textrm}{m}$ CMOS technology.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.34S no.12
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• pp.106-113
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• 1997

While driving, the low frequency interior noise below 200Hz causes the main component that irritates the auditory acoustic sense. But these passive control methods bring out increment in cost and weight of the vehicle and result in low efficiency. Recently, various ANC(Active Noise Control) methos to suppress the low frequency noise began to launch into application. In this study, we implemented the active noise control system for passenger vehicle to cancel the engine booming noise using DSP-based control unit, 4 micorphones, and 2 speakers. We used MEFX-LMS (Multiple Error Filtered X-Least Mean Square) algorithm since it can be easily implemented in real time. Also, MEFX-RLS algorithm was taken to enhance the suppression of the harmonic components of the engine booming noise inspite of its computational complexity. The performance of two adaptive algorithms were analyzed with experimental resutls.

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.127-128
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• 2006

The noise is major obstacle element in power line communication. However, because power supply networks are not designed for communication, there are various noise sources. Accordingly, a study of characteristic and cause of noise generated in low voltage transformer is important for outdoor power line communication. In this paper, we measure low voltage transformer noise in 1-30MHz using spectrum analyzer. We analyze cause and pattern of noise considering partial discharge.

• Journal of KSNVE
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• v.10 no.5
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• pp.873-879
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• 2000

Experimental investigation was conducted to study the effects of pitch angle maximum camber on the performance and noise of an axial-flow fan used in outdoor-unit of air -conditioner. For this study the axial-flow fan whose pitch angle can be varied was made and the Specific sound Pressure Level and other coefficients were measured using the anechoic fan tester. It is found that pitch angle affects more severly than the maximum camber on the fan performance. On the while the maximum camber affects much on the specific sound power level. Present results show that it is important to choose the optimum pitch angle and maximum camber to design the high-performance and low-noise axial-flow fan and specific noise measured in the anechoic fan tester can be sued effectively for the design of low-noise fan.

• ETRI Journal
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• v.24 no.3
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• pp.190-196
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• 2002

This paper presents millimeter wave monolithic microwave integrated circuit (MMIC) low noise amplifiers using a $0.15{\mu}m$ commercial pHEMT process. After carefully investigating design considerations for millimeter-wave applications, with emphasis on the active device model and electomagnetic (EM) simulation, we designed two single-ended low noise amplifiers, one for Q-band and one for V-band. The Q-band two stage amplifier showed an average noise figure of 2.2 dB with an 18.3 dB average gain at 44 GHz. The V-band two stage amplifier showed an average noise figure of 2.9 dB with a 14.7 dB average gain at 65 GHz. Our design technique and model demonstrates good agreement between measured and predicted results. Compared with the published data, this work also presents state-of-the-art performance in terms of the gain and noise figure.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.501-503
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• 2008

This paper presents the design of a 2.4 GHz low phase noise fully integrated LC Voltage-Controlled-Oscillator (VCO) in $0.18{\mu}m$ CMOS technology. The VCO is without any tail bias current sources for a low phase noise and, in which differential varactors are adopted for the symmetry of the circuit. At the same time, the use of differential varactors pairs reduces the tuning range, i.e., the frequency range versus VTUNE, so that the phase noise becomes lower. The simulation results show the achieved phase noise of -138.5 dBc/Hz at 3 MHz offset, while the VCO core draws 3.9mA of current from a 1.8V supply. The tuning range is from 2.28GHz to 2.55 GHz.

• Journal of the Korea Institute of Military Science and Technology
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• v.15 no.4
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• pp.450-457
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• 2012

In this paper, we designed low phase noise frequency synthesizer with compact size for High frequency band (Ku-band). The paper addresses merits and demerits of single loop and dual loop frequency synthesizer. The phase noise characteristics of the phase-locked loop frequency synthesizer were predicted based on the analysis for phase noise contribution of noise sources. The proposed model in this paper more accurately predicts the low phase noise frequency synthesizer with compact size for high frequency band.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.2
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• pp.383-388
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• 2007

This paper considers a low-order dynamic output feedback controller design problem. Since the proposed control law inherently has a low-pass filter property, it can alleviate the mal-effects of the sensor noise without additional filter designs. Frequency domain analysis shows the characteristics of the proposed control law against measurement noise. The effectiveness of the proposed control law is illustrated by numerical simulations with a rotary inverted pendulum and a convey-crane. Using only one integrator the proposed control law has the advantage to the stabilization problem with sensor noise as well as it can successfully replace the measurements of derivative terms in a state feedback control law.

• Journal of KSNVE
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• v.8 no.6
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• pp.1158-1165
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• 1998

Low frequency interior noise in cars is mainly due to structure-borne excitations which are related with road excitation and component vibrations such as suspension and engine mounts. In order to analyze the annoying interior noise. a technique (Transfer Path Analysis) is introduced to find a noise source and the path of that noise. In this study, TPA is reviewed theoretically and applied to investigate the case when the low frequency interior noise at front seat due to road excitations needs to be optimized. The subjective and objective appraisal was performed under the conditions that a testing vehicle traveled on asphalt at 30 km/h. so that the low frequency to be eliminated was detected. The related vibration and noise data for TPA were measured on running and static vehicle. The results reveal that the noise contribution along the z-direction of trailing arm is prominent to low frequency interior noise.

• International Journal of Highway Engineering
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• v.18 no.5
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• pp.49-56
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• 2016

PURPOSES : In this study, noise reduction effect of a two-layer porous asphalt pavement was investigated through site measurement and computer simulation. METHODS : To examine noise reduction effect, a 3 km long quiet pavement was installed by removing previous normal pavement, which had a rather low porosity. The studied site was a high-rise apartment building surrounded by the quiet pavement and Seoul ring road with heavy traffic volume, indicating relatively high background noise. RESULTS : The measurement result before and after installing the quiet pavement showed a noise reduction effect of 4.3 dB(A) at a distance of 7.5 m from the road. After validating the accuracy of simulation using SoundPLAN, the reduction in SPL(sound pressure level) at the facades by the quiet pavement was predicted by considering five different road conditions generating traffic noise from each road or in the combination of the quiet pavement and Seoul ring road. In the case of no noise from Seoul ring road, noise reduction at the facades was 4.2 dB(A) on average for 702 housing units. With background noise from Seoul ring road, however, the average SPL decreased to 2.0 dB(A). Regarding subjective response of noise, the number of housing units with a noise reduction of over 3 dB(A) was 229 out of 706 units (approximately 32%). For 77 housing units, the noise reduction was between 1~3 dB(A), while it was less than 1 dB(A) for 400 housing units. CONCLUSIONS : The overall result indicates that the quiet pavement is useful to reduce noise evenly at low and high floors compared to noise barriers, especially in the urban situation where background noise is low.