• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.8
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• pp.673-682
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• 2007

Recently the trend of automobile industry is that IQS evaluation index against a sensitivity quality is increasing. To reduce rattle noise due to speaker sound at low frequencies, it is required the advanced technology analysis process of body structure. This paper optimized the design parameters of package tray panel according to the theoretical background about robust design and suggested the design guideline for resonance avoidance and the reduction of vibrational sensitivity considering the excitation frequency of woofer speaker. And this paper described the design process of a door module panel through the sensitivity analysis in case of the door speaker excitation. Finally, the analysis of the quality deviation using mother car is suggested to guarantee the stable characteristics of vehicle vibration in the early stage of vehicle development. These improvements can lead to shortening the time needed to develop better vehicles.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.9C
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• pp.589-595
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• 2011

This paper proposes an improved multi-stage timing offset estimation scheme for orthogonal frequency division multiplexing (OFDM) systems in multipath fading channel environment. The conventional multi-stage timing offset estimation scheme is very sensitive to the random multipath components. By exploiting the sample standard deviation of the cross-correlation values, the proposed scheme achieves a robustness to the random multipath components. Simulation results demonstrate that the proposed scheme has a higher correct estimation probability and has a better mean square error (MSE) performance than the conventional scheme in multipath fading channels.

• Ocean and Polar Research
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• v.30 no.2
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• pp.149-158
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• 2008

The characteristic analysis of the estimated population parameters, i.e., standard deviation and error bound of coastal pollutant concentrations (hereafter PC, i.e., COD, TN, and TP concentrations), was carried out by using environmental data with different sampling frequency in Lake Shihwa and Incheon coastal zone. The results clearly show that standard deviation of the PC increases as its mean value increases. The error bounds of the annual mean values based on seasonally measured DO concentrations and PC data in Incheon coastal zone were estimated as ranges 2.26 mg/l, $0.68{\sim}0.86\;mg/l$, $0.62{\sim}0.80\;mg/l$, and $0.074{\sim}0.082\;mg/l$, respectively. In terms of annual mean of the DO concentration and PC in Lake Shihwa, the error bounds based on monthly measured data from 1997 to 2003 were also estimated as ranges 4.0 mg/l, 3.0 mg/l, $0.5{\sim}1.0\;mg/l$, and 0.05 mg/l, respectively. The error bound on the basis of real-time monitoring data is $7{\sim}13%$ only as compared to that of monthly measured data.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.11
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• pp.995-1000
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• 2010

With the development of the auto industry, the automobile manufacturers demand to shorten development period and reduce the cost. Compared with the traditional method, applying the virtual prototype is more economical. This paper presents a method for parameters sensitivity analysis and optimizing the performance of vehicle noise and vibration. The existing design processes were repeatedly analyzed with a focus on vehicle performance to decide the design parameters of dimension, thickness, mounting type of body and chassis systems in the vehicle development period. This paper describes the prediction technique of vehicle performance using L18 orthogonal array layout, quality deviation analysis and parameter sensitivity analysis for robust design. This paper analyzed the performance correlation equation through the frequency and sensitivity database according to a design factor change. The new concept is that the performance prediction is possible without repeated activities of test and analysis. This paper described the parameter analysis applications such as bush dynamic stiffness and bush void direction of rear suspension. Design engineer could efficiently decide the design variable using parameter analysis database in early design stage. These improvements can reduce man hour and test development period as well as to achieve stable NVH performance.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.10a
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• pp.118-120
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• 2021

In modern society, with the development of IoT technology, various digital equipment is being distributed in a wide range of fields such as CCTV and exploration robots. Accordingly, the importance of data processing is increasing, and various studies are being conducted to remove noise generated in the process of receiving data in the imaging field. Representative noise includes additive white Gaussian noise (AWGN), and existing filters for removing noise include an average filter (AF), an alpha trimmed average filter (A-TAF), and a median filter (MF). However, existing filters have a disadvantage in that they show somewhat insufficient performance in noise removal characteristics in high frequency areas. Therefore, in this paper, in order to effectively remove AWGN existing in the high frequency region, a weight filter according to a distance based on the standard deviation is proposed.

• Journal of the Korean association of regional geographers
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• v.18 no.4
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• pp.433-444
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• 2012

This study aims to examine the effect of tourists' participative motivation of a festival on satisfaction and behavior intention in terms of satisfaction, revisit intention, and recommendation based on Baekjae Cultural Festival. For this study, frequency analysis, reliability analysis, factor analysis, and multiple regression analysis were made. The survey was conducted among 287 samples for the study. The results are as follows: According to the factor analysis, five factors were drawn such as new experience, deviation from daily life, family harmony, amusement & novelty, cultural tour of Baekjae, and sociability. Festival satisfaction was affected by amusement & novelty, new experience & deviation from daily life, and cultural tour of Baekjae, while revisit intention was influenced by cultural tour of Baekjae, amusement & novelty, family harmony, and new experience & deviation from daily life respectively. On the other hand, recommendation was affected by cultural tour of Baekjae, sociability, amusement & novelty, and family harmony respectively.

• Journal of KIISE
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• v.43 no.10
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• pp.1144-1153
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• 2016

Group recommendation analyzes the characteristics and tendency of a group rather than an individual and provides relevant information for the members of the group. Existing group recommendation methods merely consider the average and frequency of a preference. However, if the users' preferences have large deviations, it is difficult to provide satisfactory results for all users in the group, although the average and frequency values are high. To solve these problems, we propose a method that considers not only the average of a preference but also the deviation. The proposed method provides recommendations with high average values and low deviations for the preference, so it reflects the tendency of all group members better than existing group recommendation methods. Through a comparative experiment, we prove that the proposed method has better performance than existing methods, and verify that it has high performance in groups with a large number of members as well as in small groups.

• Journal of the Institute of Convergence Signal Processing
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• v.20 no.3
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• pp.125-131
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• 2019

Through the 4th Industrial Revolution, various digital equipments are being distributed, and accordingly, the importance of data processing is increasing. As data processing has a great effect on the reliability of equipment, its importance is increasing, and various studies are being conducted. In this paper, we propose an algorithm to remove AWGN in consideration of the noise in the image. The proposed algorithm is used in the filtering process by inferring the standard deviation of the image noise. The noise is removed by dividing the filter for the high frequency component and the filter for the low frequency component compared with the standard deviation of the filtering mask. The proposed algorithm is simulated with the existing methods for evaluation and compared and analyzed by difference image, PSNR and profile. The proposed algorithm minimizes the effect of noise and preserves the important characteristics of the image and shows the performance of efficient noise removal.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.61-64
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• 2007

This study is dealt with a method to enhance low-frequency diffuse sound field in a scaled reverberation chamber. Because scaled reverberation chamber has not enough room volume, as a result, it shows a few room modes. So it is not build up low-frequency diffuse sound field. A Helmholtz resonator's arrangement is used to improve spatial uniformity of sound pressure at low frequency. The spatial distribution of sound field has been measured before and after control. The standard deviation of sound field has decreased at 315Hz 1/3 Octave band.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.1
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• pp.86-91
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• 2007

A sensor using quartz toning fork is presented for measuring liquid density. It consists of a PZT plate as an actuator for piezoelectric excitation and a quartz tuning fork as a sensor for resonant frequency detection. The resonant frequency is determined from the sensing voltage measured in tuning fork when the excitation frequencies of PZT actuator are swept around the resonant frequencies of tuning fork. The resonant frequency determined the liquid density. The density values of three kinds of organic solvents are measured and compared with the standard values. The experimental results are in agreement with the standard values and the maximum standard deviation is less than 9%.