• Transactions of the Korean Society of Automotive Engineers
• /
• v.7 no.6
• /
• pp.198-206
• /
• 1999

An automobile outside rear view mirror system has been analyzed and designed to reduce vibration with a finite element model. model analysis is conducted for the calculation of natural frequencies. harmonic analysis is utilized to estimate the displacements of the glass surface under dynamic loads. The model is verified with the vibration experiment of the parts and the assembled body. The structure of the mirror system is optimized for the robustness defined by the Taguchi concept. At first, many potential design variables are defined. Final design variables are selected based on the amount of contribution on the objective function. That is, sensitive variables are chose. The SN ratio in the Taguchi method is replaced by an objective function with the mean and the standard deviation of the quality characteristic. The defined objective function is appropriate in the structural design in that the vibration displacements are minimized while the robustness is improved.

• Communications for Statistical Applications and Methods
• /
• v.10 no.3
• /
• pp.749-764
• /
• 2003

In this paper we explain that normal theory likelihood-ratio tests(z, t, $x^2$. F) for mean(s) or variance(s) can be geometrically related to volume of difference of two joint pdf's. One is an estimated joint pdf under null parameter space $\omega$ and the other is an estimated joint pdf under full parameter space $\Omega$. For explanations, ‘distance between two distributions’ is defined. We study properties of it, and derive some results on the distance between two multivariate normal distributions.

• Journal of the Semiconductor & Display Technology
• /
• v.8 no.4
• /
• pp.1-5
• /
• 2009

This investigation is applied Taguchi method and the analysis of variance(ANOVA) to the reactive ion etching(RIE) characteristics of $SiO_2$ film coated on a wafer with Experimental Analysis and Optimization of $CF_4/O_2$ Plasma Etching Process mixture. Plans of experiments via nine experimental runs are based on the orthogonal arrays. A $L_9$ orthogonal array was selected with factors and three levels. The three factors included etching time, RF power, gas mixture ratio. The etching rate of the film were measured as a function of those factors. In this study, the etching thickness mean and uniformity of thickness of the RIE are adopted as the quality targets of the RIE etching process. The partial factorial design of the Taguchi method provides an economical and systematic method for determining the applicable process parameters. The RIE are found to be the most significant factors in both the thickness mean and the uniformity of thickness for a RIE etching process.

• Journal of Naturopathy
• /
• v.7 no.2
• /
• pp.39-46
• /
• 2018

Purpose: The purpose of this study was to evaluate the effect of the subjects after visiting the Gyorae forest on the activity of the autonomic nervous system. Methods: Before and after the forest bath, it was measured using a ubiquitous machine. Results: After the bath there was no significant difference in the sympathetic nerve activity (LF) of the control group, but the difference was significant in the experimental group by increasing (p<.038), and in the variance analysis, there was a significant difference between the groups (p<.014), between pre-and post-bath (p<.026), and also between the groups and pre-and post-bath (p<.018). The changes in parasympathetic activity (HF) were not significant in both the control and experimental. In the LF/HF ratio, the experimental group was significantly increased, and in the analysis of variance, there was also significant difference between group and before and after bath (p<.04). Mean pulse rate in the experimental group was a significant increase after bath (p<.026). In the change of pulse standard deviation, the value of the control and the experimental groups by variance analysis was a significant difference between the groups (p<.014). There was no difference between the mean values of the control and the experimental groups in the change of mean heart rate deviation. Conclusions: The autonomic nervous systems were activated after Gyorae forest bathing, where may be useful place for healing.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.17 no.3
• /
• pp.213-224
• /
• 1992

An encoding technique based on region splitting and vector quantization is proposed for the lower level Laplacian pyramid images. The lower level Laplacian pyramid images have lower variance than higher levels but a great influence on compression ration due to large spatial area. And so from data compression viewpoint, we subdivide them with variance thresholding into two regions such as one called : flat region” and the other “edge region”, and encode the flat region with its mean value and the edge region as vector quantization method. The edge region can be reproduced faithfully and significant improvement on compression ratio can be accomplished with a little degradation of PSNR in spite of the effect of large flat region since the codebook used is generated from the edge region only on from the entire image including the flat region. It can be verified by computer simulation results that proposed method is more efficient in compression ratio and processing time than the conventional encoding technique of vector quantization.

• Proceedings of the Acoustical Society of Korea Conference
• /
• autumn
• /
• pp.291-294
• /
• 2004

본 논문에서는 잡음의 변화(variance)가 없는 정적인 통계적 특성(Stationary Static Characteristic)을 갖는 환경에서 잡음 추정을 통해 지각 필터의 성능을 개선하는 알고리즘을 제안한다. 제안된 잡음 추정 알고리즘은 입력되는 잡음에 열화 된 신호의 묵음 구간에서 추정된 잡음을 이용하여 입력되는 잡음의 SNR을 추정 후, 대역 별로 smoothing 상수 값으로 잡음 에너지를 제어하여 첨가된 잡음을 추정함으로써 초기 추정 잡음 보다 가까운 추정 잡음을 얻을 수 있게 된다. 이는 신호를 열화 시킨 잡음을 보다 정확한 추정을 제공함으로써, 지각 필터의 응답을 개선할 수 있고 더불어 잡음에 의해 열화 된 신호의 음질을 개선할 수 있다. 또한 저 대역에 영향을 미치는 잡음인 경우 다른 방법들과는 달리 음질의 개선이 뚜렷하다. 기존의 방식과 비교를 위해 다양한 신호 대 잡음 비(signal-to-noise ratio, SNR)에서 열화 된 오디오 신호를 입력으로 사용하였다. 입력 SNR이 5dB, 10dB, 15dB와 20dB의 각각의 경우에 대하여 SSNR(Segmental SNR)과 잡음 대 마스킹 비(Noise-to-mask ratio, NMR), 음질 테스트를 수행한 결과, 청감 테스트(Mean Opinion Score, MOS Test) 결과의 향상과 음질개선의 개선을 확인할 수 있었다.

• Journal of KIISE:Computing Practices and Letters
• /
• v.16 no.2
• /
• pp.242-246
• /
• 2010

In this paper, we propose a quality assessment method of biometrics for estimating an authentication result in an user authentication system. The proposed quality assessment method is designed to compute a quality score called CIMR (Confidence Interval Matching Ratio) as a result by small-sample analysis like T-test. We use the C/MR-based quality assessment method for testing how to well draw a distinction between various biometrics in a multimodal biometric system. We also test a predictability for authentication results of obtained biometrics using the mean $\bar{X}$ and the variance $s^2$ in T-test-based CIMR. As a result, we achieved the maximum 88% accuracy for estimation of user authentication results.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
• /
• v.16 no.1
• /
• pp.26-36
• /
• 2010

Purpose: The study compared the muscle activity and ratio of upper trapezius (UT) to lower trapezius (LT) activity between acute and chronic whiplash-associated disorder (WAD) patients. Methods: Twelve healthy (male: 7), 14 acute WAD (male: 7), and 11 chronic WAD (male: 3) volunteers participated in this study. Electromyography using a surface EMG recorded the activity of the upper trapezius and lower trapezius of both shoulders (dominant and non-dominant) during $120^{\circ}$ elevation when standing and shoulder depression when sitting. The testing order was selected randomly. Subjects were asked to maintain each experimental position for 5 seconds at end range. EMG activity was normalized using the maximal voluntary isometric contraction (MVIC) elicited using a manual muscle-testing technique. One-way repeated measures analysis of variance (ANOVA) was used to compare the average root mean square (RMS) value of EMG activity for each condition. Results: The EMG activity of the dominant UT for chronic WAD subjects was significantly higher than for acute WAD subjects during $120^{\circ}$ elevation (p<.05). The EMG activity of the dominant LT for acute WAD subjects was significantly lower than for the control group (p<.05) during $120^{\circ}$ elevation. The EMG activity of the dominant LT for WAD patients was significantly lower than for the control group during shoulder depression (p<.05), and the chronic WAD patients scored significantly the lowest (p<.01). The dominant UT/LT for chronic WAD patients was significantly higher than the ratio for acute WAD subjects during shoulder depression (p<.05); this result was higher than for the control group (p<.01). The non-dominant UT/LT (ratio) for chronic WAD patients was significantly higher than the ratio for acute WAD subjects during shoulder depression (p<.05). Conclusion: The UT for chronic WAD subjects was hyperactive when compared to the acute WAD subjects, and the was hypoactive for both acute and chronic patients, therefore intra-trapezius imbalance was more prevalent during shoulder depression.

• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 2010.11a
• /
• pp.167-170
• /
• 2010

잡음 분산 값은 SNR(signal-to-noise ratio) 추정이나 MMSE(minimum mean square error) 계산, 채널 임펄스 응답의 추정 등에 사용되는 중요한 파라미터이다. 채널이 시간에 따라 변하는 무선 통신 환경에서, 신호와 섞여 있는 잡음과 간섭 신호의 정확한 추정에는 그 한계가 있으며 이로 인해 발생하는 추정 오차는 수신기의 데이터 검출 성능을 저하시킨다. 훈련열을 이용하여 채널을 추정하였을 경우 추정된 채널 임펄스 응답 신호 중 다중 경로 신호는 소수에 불과하고 나머지 대부분의 계수는 잡음 성분만을 포함하는 신호이다. 이러한 특징을 이용하여 채널의 추정 계수로 잡음 분산을 추정하는 방법이 기존에 제시되어 있다. 여기서 제안하는 알고리즘은 기존 알고리즘인 PSA(partial sample average)와 비교해 연산량에서 차이가 거의 없이 구현되며, 3GPP TDD[1]에서의 모의 실험을 통하여 기존 알고리즘보다 더 정확한 분산 값을 찾아냄을 확인하였다.

• Communications for Statistical Applications and Methods
• /
• v.22 no.6
• /
• pp.639-646
• /
• 2015

We propose simultaneous tests for mean and variance under the normality assumption. After formulating the null hypothesis and its alternative, we construct test statistics based on the individual p-values for the partial tests with combining functions and derive the null distributions for the combining functions. We then illustrate our procedure with industrial data and compare the efficiency among the combining functions with individual partial ones by obtaining empirical powers through a simulation study. A discussion then follows on the intersection-union test with a combining function and simultaneous confidence region as a simultaneous inference; in addition, we discuss weighted functions and applications to the statistical quality control. Finally we comment on nonparametric simultaneous tests.