• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.617-621
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• 2007

Recent advances in automotive noise control engineering have reduced major sound sources in the vehicle, customers perceive Buzz, Squeak and Rattle (BSR) as one of important indicators of vehicle quality and durability. As the long-term goal, we expect to establish the integrated design cycle for the reduction of BSR noise in the early stage of development, which consist of design, prediction, and evaluation procedures. This is possible only with great bulk of experimental data for BSR noise. In this paper, BSR noise is experimentally identified for vehicle doors, which have been traditionally considered as one of main sources of BSR noise. Based on this result, we proposed method for the prevention of BSR noise in the vehicle doors.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.12
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• pp.1217-1222
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• 2007

With recent advance in automotive noise control engineering reducing major sound sources in the vehicle, customers perceive Buzz, Squeak and Rattle (BSR) as one of important indicators of vehicle quality and durability. As the long-term goal, we expect to establish the integrated design cycle for the reduction of the BSR noise in the early stage of vehicle development. which consist of design, prediction and evaluation procedures. This is possible only with great bulk of experimental data for BSR noise. In this paper, BSR noise is experimentally identified for vehicle doors, which have been traditionally considered as one of main sources of BSR noise. Based on this result, we proposed systematic method for the prevention of BSR noise in the vehicle doors.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.66-70
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• 2005

Noise prediction are required as part of an environmental impact assessment. Prediction method that is used to domestic environmental impact assessment of construction site and industrial site is not applied work operation rate, work position, moving noise source, inner traffic flow, work type and height of noise source etc. The BS5228 methodology is used mainly for assessment of proposed open industrial sites(mineral extraction, landfill etc.), and larger long-term construction sites(typically for major infrastructure projects). also, estimation which consider various effect factor is possible.

• Korean Journal of Optics and Photonics
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• v.4 no.4
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• pp.487-492
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• 1993

A polarization maintaining fiber optic gyroscope was constructed having an optical loss of about 25 dB. Using the earth rotation rate as a reference, the long term stability of better than $3^{\circ}/hr$ and the rms short term noise of $0.6^{\circ}/hr/{\sqrt{Hz}}$ were obtained.

• The Journal of the Acoustical Society of Korea
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• v.21 no.6
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• pp.522-530
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• 2002

This paper introduces a neural network (NN) -based nonlinear predictor for the LP (Linear Prediction) residual. To evaluate the effectiveness of the NN-based nonlinear predictor for LP-residual, we first compared the average prediction gain of the linear long-term predictor with that of the NN-based nonlinear long-term predictor. Then, the effects on the quantization noise of the nonlinear prediction residuals were investigated for the NN-based nonlinear predictor A new NN predictor takes into consideration not only prediction error but also quantization effects. To increase robustness against the quantization noise of the nonlinear prediction residual, a constrained back propagation learning algorithm, which satisfies a Kuhn-Tucker inequality condition is proposed. Experimental results indicate that the prediction gain of the proposed NN predictor was not seriously decreased even when the constrained optimization algorithm was employed.

• Analytical Science and Technology
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• v.25 no.4
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• pp.223-229
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• 2012

Analytical signal from ICP was compensated by the light scattering of sample aerosols. Reference scattering signal was generated by a He-Ne or diode laser, monitored for the amount of aerosol producing and used for the compensation of analytical signals. The result showed that significant improvement in precision could be achieved for the short-term signal (within 1 minute) from 3.4% to 0.9% RSD in signal and 14.9% to 4.2% for the long-term (10 minutes) for Be, Pb and Co. This method is very useful not only for the pulse type but for continuous type signals especially when a nebulizer is unstable. To improve long-term precision, higher stability is required in the scattering cell and detector as well as the reduction of noise from the line between a nebulizer and plasma.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1998.10a
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• pp.271-274
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• 1998

In this paper we examine long-term memory of the financial time-series by employing the R/S analysis, the Hurst exponent estimation, and the modified R/S analysis. The null hypothesis of white-noise is tested using the NYSE daily indexes from January 1966 to July 1998, and the results show that long-range dependence exists before the apparent structural break of the Black Monday in 1987.

• Smart Structures and Systems
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• v.19 no.2
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• pp.137-149
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• 2017

Under the interference of the temperature effect, the alternation of cable force due to damages of a cable-stayed bridge could be difficult to distinguish. Considering the convenience and applicability in engineering practice, simple air or cable temperature measurements are adopted in the current study for the exclusion of temperature effect from the variation of cable force. Using the data collected from Ai-Lan Bridge located in central Taiwan, this work applies the ensemble empirical mode decomposition to process the time histories of cable force, air temperature, and cable temperature. It is evidently observed that the cable force and both types of temperature can all be categorized as the daily variation, long-term variation, and high-frequency noise in the order of decreasing weight. Moreover, the correlation analysis conducted for the decomposed variations of all these three quantities undoubtedly indicates that the daily and long-term variations with different time shifts have to be distinguished for accurately evaluating the temperature effect on the variation of cable force. Finally, consistent results in reducing the range of cable force variation after the elimination of temperature effect confirm the validity and stability of the developed method.

• Journal of Home Health Care Nursing
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• v.22 no.1
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• pp.47-58
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• 2015

Purpose: This study was aimed at understanding meal services provided at long-term care facilities. Method: Interview survey was conducted using questionnaires at 254 facilities located in the Kyung-In area. Result: Of the residents, 37.4% were eating meals unassisted. Eating places included living rooms and residents' rooms in most facilities. Major noise source was television in 63.8%. Apron was applied to all elderly residents at mealtimes in 49.6% of the facilities. Half of the facilities used feeding utensils except for ordinary spoon and chopsticks. Of the facilities having individual prosthetic devices, dentures were applied before eating in 98%, glasses in 20.2% and hearing aids in 9.2%. Most facilities included the residents' favorite foods in menu: wheres, only 9.4% offered the menu which residents could choose. Conclusion: Standard guidelines and staff education for meal services need to be provided for elderly residents.

• Smart Structures and Systems
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• v.31 no.1
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• pp.45-56
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• 2023

Vibration-based structural health monitoring is used to ensure the safety of structures by installing sensors in structures. The peak picking method, one of the applications of vibration-based structural health monitoring, is a method that analyze the dynamic characteristics of a structure using the peaks of the frequency response function. However, the results may vary depending on the person predicting the peak point; further, the method does not predict the exact peak point in the presence of noise. To overcome the limitations of the existing peak picking methods, this study proposes a new method to automate the modal analysis process by utilizing long short-term memory, a type of recurrent neural network. The method proposed in this study uses the time series data of the frequency response function directly as the input of the LSTM network. In addition, the proposed method improved the accuracy by using the phase as well as amplitude information of the frequency response function. Simulation experiments and lab-scale model experiments are performed to verify the performance of the LSTM network developed in this study. The result reported a modal assurance criterion of 0.8107, and it is expected that the dynamic characteristics of a civil structure can be predicted with high accuracy using data without experts.