• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.12
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• pp.1111-1116
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• 2013

In the present study, annoyance caused by diverse construction noises was evaluated through surveys. A survey with a total of 110 construction workers was carried out to investigate annoyance from construction noises at different construction phases. The most effective item of adverse by construction noise was annoyance and the most annoyed construction stage was destruction construction. There were high correlation between work performance and work safety as well as work safety and speech interference. Participant's noise sensitivity were significant between low and high group at work performance, work safety, speech interference.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1026-1029
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• 2003

There are always some errors in force sensing of multi-axis force sensors that aggravate sensor performance. Error sources may be classified mainly in two groups. One is structural error due to inaccuracy of sensor body, and the other is error due to noise signals existing in the sensed information. This paper presents a brief review about the principle of multi-axis force sensors, and then a method that can reduce the effect of noise signals. The method is to read digital signals in computer instead of analog voltage signals. We can eliminate the bad effect of electromagnetic waves emitted from computer and of 60 Hz noise emitted from AC source by the proposed method. The proposed method is investigated through experimental demonstration. The experimental results show the proposed method improves the sensor performance significantly.

• Proceedings of the KSPS conference
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• 2007.05a
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• pp.127-130
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• 2007

The conventional feature recombination technique is very effective in the band-limited noise condition, but in broad-band noise condition, the conventional feature recombination technique does not produce notable performance improvement compared with the full-band system. To cope with this drawback, we introduce a new technique of sub-band likelihood computation in the feature recombination, and propose a new feature recombination method by using this sub-band likelihood computation. Furthermore, the reliable sub-band selection based on the signal-to-noise ratio is used to improve the performance of this proposed feature recombination. Experimental results shows that the average error reduction rate in various noise condition is more than 27% compared with the conventional full-band speaker identification system.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.05a
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• pp.1162-1167
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• 2001

Suction valve fluttering is generated by reciprocating motions of the piston inhaling and discharging process of gas in the hermetic compressor. A reactive type suction muffler, which produces high pressure-drop because of its complicated flow path, controls the impulsive noise radiated from the flutter of suction valve. The high-pressure drop in the muffler increases the transmission loss, but reduces the EER(Energy Efficiency Ratio) of the compressor. We consider how to design the high acoustic attenuation and low pressure-drop performance to take account of the acoustic and flow performances of the suction muffler. In this study, we identified the suction noise source of compressor from the measurement of the acoustic pulsation and flutter of suction valve. We analyzed the acoustic characteristics of muffler using the finite element method, and compared the experimental and analytical characteristics of flow path of suction muffler. Theoretical predictions and experimental results are compared from the viewpoint of the acoustic performance and energy efficiency of the compressor.

• IEMEK Journal of Embedded Systems and Applications
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• v.12 no.4
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• pp.223-229
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• 2017

An angle error is a factor obstructing to track accurate position in tracking radars. And the noise incurring the angle error can be divided as follows; thermal noise and glint. In general, Extended Kalman filter used in tracking radars is designed with considering thermal noise only. The Extended Klaman filter uses a fixed measurement error covariance when updating an estimate state by using ahead state and measurement. But, a noise power varies according to the range. Therefore we purposes the adaptive Kalman filter which changes the measurement noise covariance according to the range. In this paper, we compare the performance of the Extended Kalman filter and the proposed adaptive Kalman filter by considering KSLV-I (Korean Satellite Launch Vehicles).

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.6
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• pp.405-412
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• 2002

Recently, regulations of the government and concerns of people give rise to the interest in exhaust and intake noise of passenger car as much as other vehicles. In these demands, performance prediction software with hybrid method was developed at first. Secondly, robust design was used for improving the noise reduction capacity of intake system with the performance prediction software. On the basis of the existing design, length and radios of each component that was thought to effect on the capacity of intake system was selected. The factors were arranged by using L18 table of orthogonal array and optimum value was obtained.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.1654-1660
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• 2000

Recently, the regulations from the government and the concerns of people give rise to the interest in exhaust and intake noise of passenger car as much as other vehicles. In these demands, performance prediction software was developed in the previous study. In this study, Robust design was used for improving the noise reduction capacity of intake system with the performance prediction software. On the basis of the existing design, length and radius of each component that was thought to effect to capacity of intake system was selected. At first factors are arranged by using $L_{18}$ table of orthogonal array and then optimum value can be obtained by $L_{16}$ table of orthogonal array.

• Journal of information and communication convergence engineering
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• v.8 no.6
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• pp.640-644
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• 2010

When we talk with hands-free in a car or noisy lobby, the performance of the echo canceller degrade because background noise added to echo caused by the distance from mouth to microphone is relatively long. It gives a reason for necessity of noise-robust and high convergence speed adaptive algorithm. And if acoustic echo canceller operated not perfectly, residual signal going through the echo canceller to far-end speaker remains residual echo, which degrade quality of talk. To solve this problem, post-processing needed to remove residual echo ones more. In this paper, we propose a new acoustic echo canceller, which has noise robust and high convergence speed, linked with linear predictor as a post-processor. By computer simulation, it is confirmed that the proposed algorithm shows better performance from acoustic interference cancellation (AIC) viewpoint.

• Proceedings of the Korean Information Science Society Conference
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• 1998.10c
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• pp.467-468
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• 1998

Impulsive noise appears as black and/or white spots in an image. It is usually caused by errors during the image acquisition or transmission through communication channels. This paper presents a study on the impulsive noise reduction filter of digital image. A much more effective method for removing impulse noise is weighted median filtering. But it loses some information by changing center value with no condition. We propose some new technique to change center value with some conditions. In this paper, the performance of conditional weighted median filter is compared to the commonly used median filter, mean filter, max/min filter, and weighted median filter. A quantitative comparison is performed on MSE (Mean Square Error), RMSE (Root Mean Square Error), and SNR (Signal to Noise Ratio). Proposed conditional weighted median filter can yield better performance than regular filters.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.10a
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• pp.408-413
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• 2011

In the present study, annoyance caused by diverse construction noises was evaluated through surveys and laboratory experiments. A survey with a total of 110 construction workers was carried out to investigate annoyance from construction noises at different construction phases. The most effective item of adverse by construction noise was annoyance and the most annoyed construction stage was destruction construction. Between work performance and work safety had correlation as well as between work safety and speech interference. Participant's noise sensitivity were significant between low and high group at work performance, work safety, speech interference.