• JSTS:Journal of Semiconductor Technology and Science
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• v.12 no.3
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• pp.278-285
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• 2012

A digital readout IC for capacitive sensors is presented. Digital capacitance readout circuits suffer from static capacitance of sensors, especially single-ended sensors, and require large passive elements to cancel such DC offset signal. For this reason, to maximize a dynamic range with a small die area, the proposed circuit features digital filters having a coarse and fine compensation steps. Moreover, by employing switched-capacitor circuit for the front-end, correlated double sampling (CDS) technique can be adopted to minimize low-frequency device noise. The proposed circuit targeted 8-kHz signal bandwidth and oversampling ratio (OSR) of 64, thus a $3^{rd}$-order ${\Delta}{\Sigma}$ modulator operating at 1 MH was used for pulse-density-modulated (PDM) output. The proposed IC was designed in a 0.18-${\mu}m$ CMOS mixed-mode process, and occupied $0.86{\times}1.33mm^2$. The measurement results shows suppressed DC power under about -30 dBFS with minimized device flicker noise.

• Korean Journal of Occupational Health Nursing
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• v.13 no.1
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• pp.59-69
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• 2004

Purpose: The purpose of this study is to investigate cardiovascular risk factors, their interaction, degree of cardiovascular risk and to analyze the effects of related fcators in women workers. Method: A Survey was conducted in 529 employed women in 36 workplaces from October 25, 2002 to December 12, 2002. The survey was distributed and collected by occupational health nurses working at work sites. Result: The result were as followings; The female workers had about 2 cardiovascular risk factors. 82.1% were not exercising more than 3 times a week, 45.9% reported noise-exposure, 38.2% had higher perceived stress, 25.4% were shift-workers, 10.4% were long-time workers(over 60hour/week), 4.4% were frequent drinker, 3.9% were current smokers. The rate of obesity in measured as BMI greater than 25 was 4.0%. Many cardiovascular risk factors were correlated. Job-related and health behavior-related cardiovascular risk factors were correlated statistically. Expose to noise, reported perceived stress were powerful predictors in their degree of cardiovascular risk. Conclusion; Based on the results of this study, cardiovascular prevention programs for women in workplace should be designed as a multifactorial approach, which include stress management and job-related risk factor management as essential components to be effective in addressing the needs of the population.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.7
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• pp.72-85
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• 1998

In this paper, we propose a new method that sequentially estimates TDOA(Time Delay Of Arrival) and FDOA(Frequency Delay Of Arrival) for extracting the information about the bearing and relative velocity of a target in passive radar or sonar arrays. The objective is to efficiently estimate the TDOA and FDOA between two sensor signal measurements, corrupted by correlated Gaussian noise sources in an unknown way. The proposed method utilizes the one dimensional slice function of the third order cumulants between the two sensor measurements, by which the effect of correlated Gaussian measurement noises can be significantly suppressed for the estimation of TDOA. Because the proposed sequential algoritjhm uses the one dimensional complex ambiguity function based on the TDOA estimate from the first step, the amount of computations needed for accurate estimationof FDOA can be dramatically reduced, especially for the cases where high frequency resolution is required. It is demonstrated that the proposed algorithm outperforms existing TDOA/FDOA estimation algorithms based on the ML(maximum likelihood) criterionandthe complex ambiguity function of the third order cumulant as well, in the MSE(mean squared error) sense and computational burden. Various numerical resutls on the detection probability, MSE and the floatingpoint computational burden are presented via Monte-Carlo simulations for different types of noises, different lengths of data, and different signal-to-noise ratios.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.3 s.120
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• pp.241-248
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• 2007

A study has been conducted to investigate the subjective responses of loudness and annoyance according to the exposed time of urban traffic noise in controlled laboratory environment. To make a closer inspection into psychological response relevant to noise characteristics while varying the time of exposure to noise, the subjects were presented a set of noises with different exposed time and requested to judge spontaneously on a 100-unipolar scale. To be concrete, the subjects were exposed to noises being varied in time from 15 sec up to max. 1,200 sec for the controlled traffic noise sources. So far achieved from laborious tests, it has an importance being on the logarithmic relations of perceived loudness and exposed time, say, it is more increased the perceived loudness in the sorter exposed time than in the longer exposed time. However, the trend is said to be not effective for the case of annoyance. On the other hand, the subjective impressions on relative annoyance of noise is shown to be correlated with the noise characteristics such as loudness (sones), tonality and time with logarithmic scale, the product correlation moment being calculated as $R^{2}=0.99$. The variances to be explained for annoyance assessments through varying the time of exposure were ranged between 30 % and 50% for the exposed time, $27{\sim}37%$ for tonality, and $34{\sim}20%$ for loudness, respectively With these results, hopefully, it can be helpful for those who want to work out an experimental design for evaluating an environmental noise or to quantify any psychological dimensions found in annoyance assessments.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2004.04a
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• pp.49-56
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• 2004

Model updating is a very active research field, in which significant efforts has been invested in recent years. Model updating methodologies are invariably successful when used on noise-free simulated data, but tend to be unpredictable when presented with real experimental data that are-unavoidably-corrupted with uncorrected noise content. In this paper, Reanalysis using frequency response functions for correlating and updating dynamic systems is presented. A transformation matrix is obtained from the relationship between the complex and the normal frequency response functions of a structure. The transformation matrix is employed to calculate the modified damping matrix of the system. The modified mass and stiffness matrices are identified from the normal frequency response functions by using the least squares method. One simulated system is employed to illustrate the applicability of the proposed method. The result indicate that the damping matrix of correlated finite element model can be identified accurately by the proposed method. In addition, the robustness of the new approach uniformly distributed measurement noise Is also addressed.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.2
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• pp.18-28
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• 2008

In inverse acoustic problem with nearfield sources, it is important to separate multiple acoustic sources and to measure the position of each target. This paper proposes a new algorithm by applying MUSIC(Multiple Signal Classification) to the outputs of discrete wavelet transformation with sub-band selection based on the entropy threshold, Some numerical experiments show that the proposed method can estimate the more precise positions than a conventional MUSIC algorithm under moderately correlated signal and relatively low signal-to-noise ratio case.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.4
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• pp.291-298
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• 2011

According to the developments of automobile industry, the technology to enhance noise, vibration and harshness(NVH) performance has been studying in a point of view of ride comfort and quietness. Especially the use of computer aided engineering(CAE) simulation tools such as finite element(FE) analysis allows engineers to efficiently evaluate NVH performance. This paper presents the method to bulid FE models for full vehicle including engine, transmission. suspension and steering system, also to evaluate vibration performance of full vehicle. The full vehicle model, which is discussed, is correlated with the result of the frequency response measurement in the case of the car shake performance for high speed driving.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.421-424
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• 2004

Model updating is a very active research field, in which significant efforts has been invested in recent years. Model updating methodologies are invariably successful when used on noise-free simulated data, but tend to be unpredictable when presented with real experimental data that are-unavoidably-corrupted with uncorrelated noise content. In this paper, Reanalysis using frequency response functions for correlating and updating dynamic systems is presented. A transformation matrix is obtained from the relationship between the complex and the normal frequency response functions of a structure. The transformation matrix is employed to calculate the modified damping matrix of the system. The modified mass and stiffness matrices are identified from the normal frequency response functions by using the least squares method. Full scale pseudo dynamic pier test is employed to illustrate the applicability of the proposed method. The result indicate that the damping matrix of correlated finite element model can be identified accurately by the proposed method. In addition, the robustness of the new approach uniformly distributed measurement noise is also addressed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.4C
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• pp.374-378
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• 2003

The asymptotic performance of the two-sample locally optimum rank detector for random signals buried in signal-dependent noise and additive noise is consigered in this paper. It is shown that the locally optimum rank detector, a nonparametric detector, has reasonable asymptotic performance for a class of correlated random signals, compared with the locally optimum detector. It is noteworthy that the the two-sample locally optimum rank detector perform almost the same with the one-sample locally optimum rank detector.

• Journal of KSNVE
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• v.10 no.1
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• pp.107-116
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• 2000

The gear whine noise caused by tooth profile, elastic deformation, machining error, wear is directly correlated with the transmission error of mating gear. It is very important to build up the synthesized countermeasure by the modeling of the excitation forces and analyzing the vibratory characteristics. The mathematical models on the elements of vehicle transmission which is composed of helical gears, bearings, shafts and cases are developed. The elements are assembled by the substructure synthesis method. The cases of transmission are modeled by ANSYS. The system model of vehicle transmission is also verified by the experiments.