• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1997.04a
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• pp.376-387
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• 1997

One of the main objectives of noise control act is to define and ensure application and respect of noise exposure limits. Most European countries have prepared a legal framework for noise limits either by national laws, ordinances or municipal by-laws. This paper presents the current European standards.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.783-787
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• 2007

Nowadays, vehicle becoming necessity is increasing gradually and is main cause of environmental problem. The current automobile noise measurement test method such as ISO 362 which have been used many countries contribute seriously to enforce the regulation of the noise rigidly and actively study vehicle's noise, using that method. However, the amendment of ISO 362 was completed under the international agreement due to the changes in vehicle's techniques and road conditions. In this study, the difference between the current ISO 362(or ECE R51) and new ISO 362(or new ECE R51) is estimated by the test using the practical car producing domestically because the Korean manufacturer have to be interested in new test method.

• Ocean Science Journal
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• v.41 no.3
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• pp.175-179
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• 2006

The Ieodo Ocean Research Station(IORS) is an integrated meteorological and oceanographic observation base which was constructed on the Ieodo underwater rock located at a distance of about 150 km to the south-west of the Mara-do, the southernmost island in Korea. The underwater ambient noise level observed at the IORS was similar to the results of the shallow water surrounding the Korean Peninsula (Choi et al. 2003) and was higher than that of deep ocean (Wenz 1962). The wind dependence of ambient noise was dominant at frequencies of a few kHz. The surface current dependence of ambient noise showed good correlation with the ambient noise in the frequency of 10 kHz. Especially, the shrimp sound was estimated through investigations of waveform and spectrum and its main acoustic energy was about 40 dB larger than ambient noise level at 5 kHz.

• Nuclear Engineering and Technology
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• v.41 no.10
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• pp.1315-1322
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• 2009

The present article is concerned with the application of an electrochemical noise (EN) monitoring technique to analyze the initiation and propagation of Pb-assisted stress corrosion cracking (SCC) of an Alloy 600 material in a simulated environment of a steam generator (SG) sludge pile at high temperatures. A typical increase of electrochemical current noise (ECN) and electrochemical potential noise (EPN) was frequently recorded from the EN measurement in a caustic solution with such impurities as PbO and CuO, indicating that there are localized corrosion events occurring. With the aid of microscopic and spectral analyses, the EN data involving information on such stochastic processes as uniform corrosion and the initiation and propagation of SCC, were analyzed based on a stochastic theory.

• Journal of the Institute of Convergence Signal Processing
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• v.9 no.3
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• pp.173-178
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• 2008

In this paper, we present a new impulsive noise detection technique. To remove the impulse noise without detail loss, only corrupted pixels must be filtered. In order to identify the corrupted pixels, a new impulse detector based on rank and value estimations of the current pixel is proposed. Based on the rank and value estimations of the current pixel, the new proposed method provides excellent statistics for detecting an impulse noise while reducing the probability of detecting image details as impulses. The proposed detection is efficient and can be used with any noise removal filter. Simulation results show that the proposed method significantly outperforms many other well-known detection techniques in terms of image restoration and noise detection.

• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.1
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• pp.181-188
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• 2001

The evaluation of the noise for the an existing engine was carried out to improve the current noise level. The applied techniques were 1m air-borne noise, combustion noise analysis, torsional analysis at the front pulley and sound pressure intensity. In addition, the evaluation of the possibility to the noise reduction by means of wrapping the parts was performed to propose the detailed information in engine design. In view of the obtained results, the following countermeasures were recommended to reduce the current noise level through the above methods. Furthermore, in order to assess the influence of combustion noise on the overall engine noise, the noise test was also performed by the change of intake air temperature up to 5$0^{\circ}C$ in steps of 1$0^{\circ}C$. Finally, the fixed design specifications to reduce the engine noise will be decided in consideration of the test data for proto type engine.

• ETRI Journal
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• v.27 no.5
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• pp.473-483
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• 2005

In this paper, we propose two LC voltage-controlled oscillators (VCOs) that improve both phase noise and tuning range. With both 1/f induced low-frequency noise and low-frequency thermal noise around DC or around harmonics suppressed significantly by the employment of a current-current negative feedback (CCNF) loop, the phase noise in the CCNF LC VCO has been improved by about 10 dB at 6 MHz offset compared to the conventional LC VCO. The phase noise of the CCNF VCO was measured as -112 dBc/Hz at 6 MHz offset from 5.5 GHz carrier frequency. Also, we present a bandwidth-enhanced LC VCO whose tuning range has been increased about 250 % by connecting the varactor to the bases of the cross-coupled pair. The phase noise of the bandwidth-enhanced LC-tank VCO has been improved by about 6 dB at 6 MHz offset compared to the conventional LC VCO. The phase noise reduction has been achieved because the DC-decoupling capacitor Cc prevents the output common-mode level from modulating the varactor bias point, and the signal power increases in the LC-tank resonator. The bandwidth-enhanced LC VCO represents a 12 % bandwidth and phase noise of -108 dBc/Hz at 6 MHz offset.

• Journal of the Korea Society of Computer and Information
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• v.21 no.3
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• pp.91-96
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• 2016

We have surrounded undesired living noises in our life. One of biggest noises coming out of range hood during cooking in the kitchen. A range hood is one of the most important appliances in the kitchen because it ventilates polluted air out during cooking, and maintains air quality in the kitchen. But current kitchen range hoods bring up some issues; First, the range hoods consume massive amount of standby power not in use condition. Second, current models have designed manual fan operating system with sudden onset of noise with starting. In this paper, we propose an auto control system entire processes from air ventilation to noise reduction. Our system is consist of three parts (Eco-sensors pack, Main Controller and Active Noise Controller); Eco-sensors pack detects air pollution of kitchen areas and sends the detection values to Main Controller. Main Controller determines operation of range hood by detected values. Active Noise Controller is located inside of the range hood. It received starting signals from Main Controller which elicits degrees of polluted air condition and fan operating speed from 1 to 3. Once Active Noise Controller detected the signals, it runs a ventilating fan until new value from Main Controller becomes 0. while the range hood works, A noise cancellation algorithm inside of Active Noise Controller become activated to reduce levels of noise. As a result, the proposed system clearly shows reduction in power consumption include standby power and decreases in levels of noise.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.2
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• pp.639-643
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• 2018

As electronic systems become smaller and more portable, the need for power conversion continues to increase. In addition, system stability must be ensured from switching noise due to power conversion efficiency and power conversion system miniaturization. Therefore, countermeasures to reduce switching noise during power conversion are essential. In this paper, a DC/DC buck converter circuit is constructed, and the characteristics of switching noise generated when changing the parts layout in a four-layer printed circuit board (PCB) structure with a reference plane are compared and analyzed. In addition, switching noise characteristics were compared and analyzed through simulations when the parts layout was different in a two-layer PCB structure from which the reference planes were removed. As a result, it was confirmed that the radiated emissions characteristic is reduced by 12dB and the conducted emissions characteristic decreased by 7dB to 8dB, according to the current return path in the four-layer PCB structure. Thus, it was confirmed that the noise characteristics can be improved according to the configuration of the current return path when the power conversion circuit is designed.

• Journal of IKEEE
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• v.7 no.1 s.12
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• pp.72-79
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• 2003

Classical designs of optical transimpedance preamplifier for p-i-n photodiode receiver circuits generally employ common source transimpedance input stages. In this paper, we explore the design of a class of current-mode optical transimpedance preamplifier based upon common gate input stages. A feature of current-mode optical transimpedance preamplifier is high gain and high bandwidth. The bandwidth of the transimpedance preamplifier can also be increased by the capacitive peaking technique. In this paper we included the development and application of a circuit analysis technique based on the minimum noise. We develop a general formulation of the technique, illustrate its use on a number of circuit examples, and apply it to the design and optimization of the low-noise transimpedance amplifier. Using the noise minimization method and the capacitive peaking technique we designed a transimpedance preamplifier with low noise, high-speed current-mode transimpedance preamplifier with a 1.57GHz bandwidth, and a 2.34K transimpedance gain, a 470nA input noise current. The proposed preamplifier consumes 16.84mW from a 3.3V power supply.