• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.4
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• pp.375-381
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• 2011

The primary aim of this study is to investigate the probabilistic characteristics of the fatigue parameters that describe the fatigue crack growth behavior in magnesium alloy. Statistical fatigue crack propagation experiments have been performed on rolled AZ31 magnesium alloy CT specimens with different specimen thickness, load ratio, and maximum load at ambient temperature in a laboratory. Using the statistical fatigue data obtained from these experiments, the goodness-of-fit of the probability distribution of the fatigue behavior parameters is evaluated in this study by performing statistical analyses. The crack growth rate coefficient is a fatigue parameter having a very large COV(Coefficient of Variation), but the variation of a crack growth rate exponent is not substantial. It is considered that a crack growth rate exponent can be a material constant. It is also found that the best fit probability distribution of the parameters such as the crack growth rate coefficient and crack growth rate exponent for a magnesium alloy is a three-parameter Weibull distribution, and two-parameter Weibull distribution is a good distribution only for the crack growth rate coefficient.

• Journal of the Korean Home Economics Association
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• v.43 no.11 s.213
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• pp.59-71
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• 2005

The purpose of this study was to observe the makeup behavior and cosmetics preference based on the segmented age group and fashion appearance interested group. The target consumers were women aged in their 20's. We distributed 443 questionnaires and conducted statistical analysis using SPSS program for the 400 reliable questionnaires. Statistical analyses included frequency, Chi-square test, t-test, ANOVA and cluster analysis(K-means). The results of this study were as follows: 1. There was a significant association between specific cosmetic items currently used and segmented age group. The age 24-29 had more basic makeup than color makeup, compared to the age 20-23 group. There was a statistical difference between the highly interested group and the lowly interested group in fashion and beauty. The group of highly interested in fashion and beauty considered trendy colors, while the group of lowly interested in fashion and beauty used their favorite color as an important factor in purchasing makeup products. 2. There was a significant difference in the preference of lip colors and textures, eye shadows textures, types of eye liner and types of foundation according to segmented age groups. 3. Those who sought 'sexy' images preferred red/wine/purple lipstick colors, and green/blue/violet eye shadow colors. They significantly preferred jell/liquid type eye liner and liquid type foundation. Those who sought 'pure' images preferred orange colors and glossy textures of lipsticks. Those who sought 'elegant' and 'intellectual' images preferred pearl type eye shadow.

• Geomechanics and Engineering
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• v.21 no.2
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• pp.201-206
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• 2020

A stress-induced brittle failure in deep tunneling generates spalling and slabbing, eventually causing a v-shaped notch formation. An empirical relationship for the depth of the notch to the maximum tangential stress assuming an equivalent circular cross-section was proposed (Martin et al. 1999). While this empirical approach has been well recognized in the industry and used as a design guideline in many projects, its applicability to a non-circular opening is worth revisiting due to the use of equivalent circular profile. Moreover, even though the extent of the notch also contributes to notch failure, it has not been estimated to date. When the estimate of both the depth and the extent of notch are combined, a practical and economically justifiable support design can be achieved. In this study, a new methodology to assess the depth as well as the extent of notch failure is developed. Field data and numerical simulations using the Cohesion Weakening Frictional Strengthening (CWFS) model were collected and correlated with the three most commonly accepted failure criteria (σ₁/σ₃, D_is=σ_max/σ_c, σ_dev/σ_cm). For the numerical analyses, the D-shaped tunnel was used since most civil tunnels are built to this profile. Inferential statistical analysis is applied to predict the failure range with a 95% confidence level. Considering its accuracy and simplicity, the new correlation can be used as an enhanced version of failure assessment.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.39 no.2
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• pp.105-115
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• 2013

In Korea, the human skin tests to evaluate the anti-wrinkles and whitening effect have been accomplished in accordance with the KFDA guideline. Regarding the data of the visual assessment and machinery evaluation of the results for the human skin test, unpaired t-test have been used in order to compare between the test and the control groups and paired t-test for the comparison of effects for before and after. Descriptive statistics such as frequency analyses was used for the questionnaire evaluation data. In many cases of the European and American clinical test centers, the methodology and the statistical analysis were similar to ours. But, the documentation obtained by repeated application from identical individual has high relation. For this reason, it is desirable to apply RM ANCOVA and RM ANOVA to a visual assessment and machinery evaluation. We suggested that RM ANCOVA and RM ANOVA is the new approach to statistical analysis of human test data of functional cosmetics.

• Journal of Broadcast Engineering
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• v.12 no.6
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• pp.555-564
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• 2007

Discrete cosine transform (DCT) coefficient dropping is well recognized as an efficient rate adaptation transcoding in motion-compensated (MC)-DCT based MPEG-compressed videos. However, in this scheme, the errors incurred by the DCT coefficient-dropping are propagated and often result in significant visual quality degradation. This paper presents two propositions describing well the statistical properties of propagated errors. That is, we propose that the DCT error of the current frame is not correlated to the propagated errors of the previous frames. We also propose that the overall distortions in a given frame can be approximated as the sum of the DCT error of the current frame and the propagated errors from the previous frames. Then, it is shown that several computer simulations with different video sequences verify the effectiveness of the proposed statistical analyses.

• The Korean Journal of Malacology
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• v.26 no.3
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• pp.245-254
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• 2010

For the studies of germ cell development and maturation in the ovary, the gametogenic cycle and the number of spawning seasons per year in female Ruditapes philippinarum were investigated by quantitative statistical analysis using an Image Analyzer System. Compared with the results by qualitative and quantitative analyses, monthly variations in female gonad indice by qualitative histological analysis showed a pattern similar to that of the female gametogenic cycle calculated by quantitative statistical analysis. The number of spawning seasons occurred once per year, from June to October. In quantitative statistical analysis using an image analyzer system, monthly changes in the portions (%) of the ovary area to total tissue areas in females increased in March and reached a maximum in May, and then showed a rapid decrease from June to October when spawning occurred. And also monthly changes in portions (%) of follicle areas to the ovary area and in portions of oocyte areas to ovarian tissue areas in females began to increase in March and reached a maximum in May, and then. rapidly dropped from June to October when spawnig occurred. From these data, it is apparent that the number of spawning seasons occurred once per year, from June to October. Monthly changes in the number of the oocyte per $mm^2$ and in mean diameter of the oocyte in captured image which were calculated for each female slide showed a maximum in May and reached the minimum from December to February. Therefore, female R. philippinarum showed a unimodal gametogenic cycle during the year.

• Journal of Preventive Medicine and Public Health
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• v.52 no.2
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• pp.140-144
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• 2019

Objectives: Investigating the survival of patients with cancer is vitally necessary for controlling the disease and for assessing treatment methods. This study aimed to compare various statistical models of survival and to determine the survival rate and its related factors among patients suffering from lung cancer. Methods: In this retrospective cohort, the cumulative survival rate, median survival time, and factors associated with the survival of lung cancer patients were estimated using Cox, Weibull, exponential, and Gompertz regression models. Kaplan-Meier tables and the log-rank test were also used to analyze the survival of patients in different subgroups. Results: Of 102 patients with lung cancer, 74.5% were male. During the follow-up period, 80.4% died. The incidence rate of death among patients was estimated as 3.9 (95% confidence [CI], 3.1 to 4.8) per 100 person-months. The 5-year survival rate for all patients, males, females, patients with non-small cell lung carcinoma (NSCLC), and patients with small cell lung carcinoma (SCLC) was 17%, 13%, 29%, 21%, and 0%, respectively. The median survival time for all patients, males, females, those with NSCLC, and those with SCLC was 12.7 months, 12.0 months, 16.0 months, 16.0 months, and 6.0 months, respectively. Multivariate analyses indicated that the hazard ratios (95% CIs) for male sex, age, and SCLC were 0.56 (0.33 to 0.93), 1.03 (1.01 to 1.05), and 2.91 (1.71 to 4.95), respectively. Conclusions: Our results showed that the exponential model was the most precise. This model identified age, sex, and type of cancer as factors that predicted survival in patients with lung cancer.

• Advances in concrete construction
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• v.10 no.6
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• pp.479-488
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• 2020

The experimental and numerical works were carried out on high performance fiber reinforced concrete (HPFRC) with w/cm ratios ranging from 0.25 to 0.40, fiber volume fraction (Vf)=0-1.5% and 10% silica fume replacement. Improvements in compressive and flexural strengths obtained for HPFRC are moderate and significant, respectively, Empirical equations developed for the compressive strength and flexural strength of HPFRC as a function of fiber volume fraction. A relation between flexural strength and compressive strength of HPFRC with R=0.78 was developed. Due to the complex mix proportions and non-linear relationship between the mix proportions and properties, models with reliable predictive capabilities are not developed and also research on HPFRC was empirical. In this paper due to the inadequacy of present method, a back propagation-neural network (BP-NN) was employed to estimate the 28-day compressive strength of HPFRC mixes. BP-NN model was built to implement the highly non-linear relationship between the mix proportions and their properties. This paper describes the data sets collected, training of ANNs and comparison of the experimental results obtained for various mixtures. On statistical analyses of collected data, a multiple linear regression (MLR) model with R2=0.78 was developed for the prediction of compressive strength of HPFRC mixes, and average absolute error (AAE) obtained is 6.5%. On validation of the data sets by NNs, the error range was within 2% of the actual values. ANN model has given the significant degree of accuracy and reliability compared to the MLR model. ANN approach can be effectively used to estimate the 28-day compressive strength of fibrous concrete mixes and is practical.

• The Journal of Advanced Prosthodontics
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• v.15 no.1
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• pp.22-32
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• 2023

PURPOSE. Digital technology has enabled improvements in the fitting accuracy of denture bases via milling techniques. The aim of this study was to evaluate the trueness and precision of digital and analog techniques for manufacturing complete dentures (CDs). MATERIALS AND METHODS. Sixty identical CDs were manufactured using different production protocols. Digital and analog technologies were compared using the reference geometric approach, and the Δ-error values of eight areas of interest (AOI) were calculated. For each AOI, a precise number of measurement points was selected according to sensitivity analyses to compare the Δ-error of trueness and precision between the original model and manufactured prosthesis. Three types of statistical analysis were performed: to calculate the intergroup cumulative difference among the three protocols, the intergroup among the AOIs, and the intragroup difference among AOIs. RESULTS. There was a statistically significant difference between the dentures made using the oversize process and injection molding process (P < .001), but no significant difference between the other two manufacturing methods (P = .1227). There was also a statistically significant difference between the dentures made using the monolithic process and the other two processes for all AOIs (P = .0061), but there was no significant difference between the other two processes (P = 1). Within each group, significant differences among the AOIs were observed. CONCLUSION. The monolithic process yielded better results, in terms of accuracy (trueness and precision), than the other groups, although all three processes led to dentures with Δ-error values well within the clinical tolerance limit.

• Journal of the Korean Academy of Esthetic Dentistry
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• v.26 no.1
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• pp.17-23
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• 2017

Purpose: This retrospective study is to evaluate whether the timing of implant placement and the result of esthetic outcomes are related. Materials and Methods: Among the patients who had undergone single implant surgery on anterior area from 2010 to 2013 in Veterans Health Service Medical Center, 34 implants in 27 patients (24 male and 3 female) were selected and categorized into 3 groups according to the timing of placement, which are group D (Delay), group E (Early) and group I (Immediate). Aesthetic indices used included the Pink Esthetic Score (PES). It has 7 variables scores, such as mesial papilla, distal papilla, a level of soft-tissue margin, soft-tissue contour, alveolar process, soft-tissue color, and soft-tissue texture. Each variable ranges from 0 to 2, therefore total 14 points are highest. All patients were received by regular follow-up at least 1-year. One examiner measured PES on the intraoral photos. Each patient was considered as a statistical unit for statistical analysis. Statistical analyses were performed using a commercially available statistical software (SPSS Statistics 21.0, IBM Corp., Armonk, NY, USA). Kruskal-Wallis test was used for inter-group comparisons. Statistical significance was set at P<0.05. Result: Mean score in Group D, Group I, and Group E were $11.5{\pm}1.5$, $11.4{\pm}1.8$, and $11.3{\pm}1.8$ respectively. In Kruskal-Wallis test, there are no differences (P=0.989). Conclusion: In this limited study suggests that clinical aesthetic results can be achieved with all treatment protocols. Finally, various factors can be considered to produce the esthetic results.