• Journal of the Institute of Electronics Engineers of Korea SP
• /
• v.47 no.5
• /
• pp.222-228
• /
• 2010

In this paper, we propose a new approach to noise estimation incorporating spectral deviation with soft decision scheme to enhance the intelligibility of the degraded speech signal in non-stationary noisy environments. Since the conventional noise estimation technique based on soft decision scheme estimates and updates the noise power spectrum using a fixed smoothing parameter which was assumed in stationary noisy environments, it is difficult to obtain the robust estimates of noise power spectrum in non-stationary noisy environments that spectral characteristics of noise signal such as restaurant constantly change. In this paper, once we first classify the stationary noise and non-stationary noise environments based on the analysis of spectral deviation of noise signal, we adaptively estimate and update the noise power spectrum according to the classified noise types. The performances of the proposed algorithm are evaluated by ITU-T P. 862 perceptual evaluation of speech quality (PESQ) under various ambient noise environments and show better performances compared with the conventional method.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.21 no.4
• /
• pp.353-359
• /
• 1999

Purpose : A new method of lateral cephalometric analysis for midface, focusing on zygomatic bone, was created in this study, and measured in Korean adults. The purposes of this study are understanding about new approach for midfacial depression, especially zygomatic bone, and using to make adequate diagnosis and treatment plan. Materials and methods : In this study, esthetic Korean adults, 25 males and 25 females who were between $0^{\circ}$ and $4^{\circ}$ in ${\angle}ANB$, and between 62% and 70% in P/A facial height ratio, and had normal overbite and overjet, were used. Orbitale(Or) and Soft tissue orbitale(Or') were used for indicators of anteroposterior position of zygomatic area. And, mean value and standard deviation of linear and angular measurements, and ratio about each linear measurements, were obtained. then, standard deviation diagram - wiggle diagram - was made for visualization of results. Results : Mean values, standard deviations and ranges of 19 measurements were obtained, and among them, 5 linear measurements that had large standard deviation were excluded and the others were used for making standard deviation diagram. In standard deviation diagram, the following results were obtained. 1. If the measurements are located on more left side of mean-value-vertical -line, the potential of midfacial hypoplasia are stronger, especially zygomatic area. 2. If the measurements are located on more right side of mean-value-vertical-line, the potential of midfacial hypoplasia are decreased. Conclusion : This study presented a new method of lateral cephalometric analysis focusing on zygomatic bone in Korean adults. We expect that the results of this study can be used as parameter when clinicians make decisions about diagnosis and treatment plan for rehabilitation of esthetics and function. But, it is necessary to prove its usefulness, and to further evaluate the results.

• Journal of Biosystems Engineering
• /
• v.36 no.4
• /
• pp.285-289
• /
• 2011

Muscle fatigue is characterized as a progressive increase in discomfort arising from the active muscle at moderate load levels are maintained. The median frequency is the most commonly used as a parameter to describe muscle fatigue. However, the estimate of the median frequency is difficult to indicate muscle fatigue because of its high standard deviation and instability. This paper investigates the power changes of the appropriate low frequency band as a fatigue parameter in EMG during isotonic exercise. To select the appropriate band, linear regression lines are employed to calculate the slopes and the coefficient of determination. Three females and seven males volunteered to participate in surface EMG recordings placed on the biceps brachii and each recording experiment continued until their exhaustion. The results of experiment shows that the power changes of the selected low frequency band (15~45 Hz) have linear slopes and high determinant coefficients. Therefore, this fatiguing parameter using the power changes of the low frequency band is valid to measure the state of muscular fatigue.

• Journal of Biomedical Engineering Research
• /
• v.38 no.5
• /
• pp.219-226
• /
• 2017

Penalized-likelihood (PL) reconstruction methods for transmission tomography are known to provide improved image quality for reduced dose level by efficiently smoothing out noise while preserving edges. Unfortunately, however, most of the edge-preserving penalty functions used in conventional PL methods contain at least one free parameter which controls the shape of a non-quadratic penalty function to adjust the sensitivity of edge preservation. In this work, to avoid difficulties in finding a proper value of the free parameter involved in a non-quadratic penalty function, we propose a new adaptive method of space-variant smoothing with a simple quadratic penalty function. In this method, the smoothing parameter is adaptively selected for each pixel location at each iteration by using the image roughness measured by a pixel-wise standard deviation image calculated from the previous iteration. The experimental results demonstrate that our new method not only preserves edges, but also suppresses noise well in monotonic regions without requiring additional processes to select free parameters that may otherwise be included in a non-quadratic penalty function.

• Journal of Korean Society for Quality Management
• /
• v.46 no.1
• /
• pp.39-74
• /
• 2018

Purpose: For more than 30 years, robust parameter design (RPD), which attempts to minimize the process bias (i.e., deviation between the mean and the target) and its variability simultaneously, has received consistent attention from researchers in academia and industry. Based on Taguchi's philosophy, a number of RPD methodologies have been developed to improve the quality of products and processes. The primary purpose of this paper is to review and discuss existing RPD methodologies in terms of the three sequential RPD procedures of experimental design, parameter estimation, and optimization. Methods: This literature study composes three review aspects including experimental design, estimation modeling, and optimization methods. Results: To analyze the benefits and weaknesses of conventional RPD methods and investigate the requirements of future research, we first analyze a variety of experimental formats associated with input control and noise factors, output responses and replication, and estimation approaches. Secondly, existing estimation methods are categorized according to their implementation of least-squares, maximum likelihood estimation, generalized linear models, Bayesian techniques, or the response surface methodology. Thirdly, optimization models for single and multiple responses problems are analyzed within their historical and functional framework. Conclusion: This study identifies the current RPD foundations and unresolved problems, including ample discussion of further directions of study.

• The Transactions of the Korean Institute of Electrical Engineers D
• /
• v.54 no.4
• /
• pp.274-283
• /
• 2005

Coronary Perfusion Pressure(CPP) is known for the most important parameter related to the Return of Spontaneous Circulation (ROSC), however, clinically measuring CPP is difficult either invasive or non-invaisive method. En this paper, we analyze the correlation between the extracted parameter from VF ECG wave and the CPP with the statistical method, and predict CPP value using the extracted parameters within significance level. the extracted parameters are median frequency(MF), peak frequency(PF), average segment amplitude(ASA), MSA(maximum segment amplitude), Two parameters, MF, and ASA are selected in order to predict CPP value with general regression neural network, and then we evaluated the agreement statistics between the simulated CPP and the measured CPP. In conclusion, the mean and variance of the difference between the simulated CPP and the measured CPP are 8.9716±1.3526 mmHg, and standard deviation 6.4815 mmHg with one hundred-times training and test results. the simulated CPP and the measured CPP are agreed with the overall accuracy $90.68\%$ and kappa coefficient $81.14\%$ as a discriminant parameter of ROSC.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.57 no.4
• /
• pp.729-734
• /
• 2008

Vibroarthrographic(VAG) signals, emitted by human knee joints, are non-stationary and multi-component in nature and time-frequency distributions(TFD) provide powerful means to analyze such signals. The objective of this paper is to classify VAG signals, generated during joint movement, into two groups(normal and patient group) using the characteristic parameters extracted by time-frequency transform, and to evaluate the classification accuracy. Noise within TFD was reduced by singular value decomposition and back-propagation neural network(BPNN) was used for classifying VAG signals. The characteristic parameters consist of the energy parameter, energy spread parameter, frequency parameter, frequency spread parameter by Wigner-Ville distribution and the amplitude of frequency distribution, the mean and the median frequency by fast Fourier transform. Totally 1408 segments(normal 1031, patient 377) were used for training and evaluating BPNN. As a result, the average value of the classification accuracy was 92.3(standard deviation ${\pm}0.9$)%. The proposed method was independent of clinical information, and showed good potential for non-invasive diagnosis and monitoring of joint disorders such as osteoarthritis and chondromalacia patella.

• Korean Journal of Metals and Materials
• /
• v.50 no.10
• /
• pp.721-728
• /
• 2012

This paper evaluates the reliability of creep rupture life under service conditions of Alloy 617, which is considered as one of the candidate materials for use in a very high temperature reactor (VHTR) system. A Z-parameter, which represents the deviation of creep rupture data from the master curve, was used for the reliability analysis of the creep rupture data of Alloy 617. A Service-condition Creep Rupture Interference (SCRI) model, which can consider both the scattering of the creep rupture data and the fluctuations of temperature and stress under any service conditions, was also used for evaluating the reliability of creep rupture life. The statistical analysis showed that the scattering of creep rupture data based on Z-parameter was supported by normal distribution. The values of reliability decreased rapidly with increasing amplitudes of temperature and stress fluctuations. The results established that the reliability decreased with an increasing service time.

• Journal of Korean Society for Quality Management
• /
• v.43 no.1
• /
• pp.57-66
• /
• 2015

Purpose: The purpose of this study is to apply the constrained Bayesian estimation methodology for product quality control process and prove the effectiveness of the product management by comparing with the well-known Bayes estimator through data performance result. Methods: The Bayes and constrained Bayes estimators were produced based on the theoretical background and for confirming the effectiveness of suggested application, the deviation index was defined and calculated for the comparison. Results: The statistical analysis result shows that applying the suggested estimation methodology, that is, constrained Bayes estimator improves the effectiveness of the index with regard to reduce the error by matching the first two empirical moments. Conclusion: Considering the advanced Bayesian approaches such as constrained Bayes estimation for the product quality control process, the newly defined deviation index reduces the error for estimating the parameter histogram which is reflected both location and deviation parameters and furthermore various Bayesian perspective approaches seems to be meaningful for managing the product quality control process.

• Wind and Structures
• /
• v.11 no.5
• /
• pp.361-376
• /
• 2008

This paper considers internal pressure fluctuations for a range of building volumes and dominant wall opening areas. The study recognizes that the air flow in and out of the dominant opening in the envelope generates Helmholtz resonance, which can amplify the internal pressure fluctuations compared to the external pressure, at the opening. Numerical methods were used to estimate fluctuating standard deviation and peak (i.e. design) internal pressures from full-scale measured external pressures. The ratios of standard deviation and peak internal pressures to the external pressures at a dominant windward wall opening of area, AW are presented in terms of the non-dimensional opening size to volume parameter, $S^*=(a_s/\bar{U}_h)^2(A_W^{3/2}/V_{Ie})$ where $a_s$ is the speed of sound, $\bar{U}_h$ is the mean wind speed at the top of the building and $V_{Ie}$ is the effective internal volume. The standard deviation of internal pressure exceeds the external pressures at the opening, for $S^*$ greater than about 0.75, showing increasing amplification with increasing $S^*$. The peak internal pressure can be expected to exceed the peak external pressure at the opening by 10% to 50%, for $S^*$ greater than about 5. A dominant leeward wall opening also produces similar fluctuating internal pressure characteristics.