• Journal of Korean Society of Transportation
• /
• v.20 no.1
• /
• pp.55-63
• /
• 2002

It has been known well that Traffic Conflict Technique(TCT) used to evaluate the safety of intersections in the case of shortage of traffic accidents data and surveying time. Because data for using in traffic conflict technique that is collected by trained surveyors, it is rely on the knowledge, experience and the characteristics of them. The data of surveying generate varying result. So, its variance must minimize and then it is considered of calculating in traffic conflict technique however obviously technique to minimize has not developed until now. So, this paper has a focus on the technical method to minimize the variance. For this, it applied the fuzzy reasoning theory to the existed traffic conflict technique that is the most comprehensive method in the country and then developed the new traffic conflict technique model. Fuzzy reasoning theory is a very appropriate method for minimizing the variance among surveyors because it can systematically calculate the uncertainty of surveyors by approximation reasoning structure. The result of analysis from pilot study, the new Procedure in this Paper minimized the variance by 53 Percentiles and it increased the value of conversion factor two times than the exited traffic conflict technique. The method proposed in this paper, it can be used for evaluating the safety of intersection, and before and after analysis of improving Project of black spots.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.36 no.7
• /
• pp.769-776
• /
• 2012

The damage analysis method in this paper needs a material property and failure criteria. The material properties and the failure criteria could be easily obtained from the results of notched bar tensile tests carried out on other materials studied previously. However, for the cast stainless steel (CF8M) material in this paper, because of the variance in the results from notched bar tensile tests under the same conditions, the material property and the failure criteria could be obtained differently, depending on the analyzer. Therefore, a proper procedure that can confirm the material property and failure criteria are needed. In this work, the averaged material property was obtained from the notched bar with a 16-mm notch radius, and three failure criteria for CF8M material by finite element analysis were obtained. Applying the material property and the failure criteria, FE damage analysis for the J-R fracture toughness test was conducted. For validation, the simulated results were compared with the experimental results.

• Journal of Aerospace System Engineering
• /
• v.18 no.2
• /
• pp.104-116
• /
• 2024

A satellite is ultimately verified by performing a coupled load analysis with the launch vehicle. To increase the accuracy of the coupled load analysis results, it is important to have good accuracy of the finite element model. Therefore, finite element model correlation is essential. In general, model correlation is performed by changing the material properties and thickness one by one, but this process takes a lot of time and cost. The current paper proposes an efficient model correlation method using optimization. Significant variables were selected through analysis of variance, and the time and cost required for analysis and optimization were reduced by using the Kriging surrogate model. The method proposed in this paper can be applied only with the vibration test results, and it has a great advantage in terms of efficiency in that it can significantly reduce the numerical calculation cost and time required.

• Journal of Korean society of Dental Hygiene
• /
• v.12 no.3
• /
• pp.521-531
• /
• 2012

Objectives : The aim of this study was to evaluate the relation between the state of dental health(number of natural teeth) and nutritional status of Korean elderly using Korean Dietary Reference Intakes, which was an objective standard for nutritional intake based on database of Korea National Health and Nutrition Examination Survey, large scale of sample obtained by the government. Methods : Complex sampling procedure was used to analyze the fourth data(2007-2009) of Korea National Health and Nutrition Examination Survey. When preparing planning file, the estimator of variance as a stratification variance (variance name : kstrata), population of survey unit as a cluster variance(variance name : PSU), and previous exam and nutritional related weighted as a weighted were analyzed by considering reproduced survey and nutritional related total weighted. Complex samples chi-square test was used to estimate the relation between number of natural teeth and inadequate intake and relation factors included in the model were analyzed by complex samples logistic regression analysis. Results : The group of edentulous had a higher risk to intake less nutrient, except calcium, riboflavin and vitamin C than recommended level comparing to reference group which had natural teeth more than 20(phosphate : OR=1.763; 95% CI=1.273-2.443, thiamine : OR=1.748; 95% CI=1.276-2.395, protein : OR=1.610; 95% CI=1.213-2.138). Conclusions : The number of teeth in Korean elderly over 65 years old had a relation with nutritional status in this investigation. Especially, intake level of nutrients was different between the edentulous group and the reference group. Therefore, dental health care is needed from young and middle age to keep health dental condition for through whole life as well as old age. Although the dental condition of the aged is not good, it is evitable to educate them about the relation between dental health and nutritional ingestion to take balanced nutrition, we think.

• Physical Therapy Rehabilitation Science
• /
• v.5 no.3
• /
• pp.132-137
• /
• 2016

Objective: Eversion of the foot is created with internal rotation of the shank, and inversion of the foot is created with external rotation of the shank. The purpose of the study was to investigate the effect of continuous changes in the angle of the subtalar joint on lower extremity alignments. Design: Cross-sectional study. Methods: Seventeen healthy young adult subjects recruited. The subjects were asked to stand up in a natural standing position on a footplate with eye open and equal weight on each foot for 10s in two different conditions: The right subtalar joint was everted continuously $0^{\circ}-20^{\circ}$ and in separate segments of $0^{\circ}$, $5^{\circ}$, $10^{\circ}$, $15^{\circ}$, $20^{\circ}$. The averages of three trials were used. The observation of the changes in the lower extremity was performed with the use of 3-dimensional motion analysis. For data analysis, the SPSS 18.0 software using paired t-test and repeated measures analysis of variance (ANOVA) was applied. Results: The angle was significantly increased at the horizontal rotation angle of the shank, thigh, and ankle without anterior rotation of the pelvis (p<0.05). The maximum horizontal rotation angle at the thigh on $20^{\circ}$ was $-4.52^{\circ}$ in static, and $-3.10^{\circ}$ in the dynamic conditions compared to $0^{\circ}$. Conclusions: Increased unilateral foot pronation, thigh, shank, ankle horizontal rotation variance was significantly effective. The observation of the changes in foot abduction with the use of a 3-dimensional motion analysis augmented in predicting the angle values of each segment of the lower extremity. In further studies, a comparison of the right and left subtalar joints need to be investigated.

• Advances in materials Research
• /
• v.13 no.4
• /
• pp.299-319
• /
• 2024

Due to higher strength-to-weight ratio of composite laminates, they find uses in many weight-sensitive applications like aerospace, automobile and marine structures. From a reliability point of view, accurate prediction of failure of these structures is important. Due to the complexities in the manufacturing processes of composite laminates, there is a variation in the material properties and geometric parameters. Hence stochastic aspects are important while designing the composite laminates. Many existing works of composite laminate failure analysis are based on the deterministic approach but it is important to consider the randomness in the material properties, geometry and loading to predict accurate failure loads. In this paper the statistics of the ultimate failure load of the [0/θ]_s laminated composite plate (LCP) containing the edge crack and voids subjected to the tensile loading are presented in terms of the mean and coefficient of variance (COV). The objective is to better the efficacy of laminate failure by predicting the statistics of the ultimate failure load of LCP with random material, geometric and loading parameters. The stochastic analysis is done by using the extended finite element method (XFEM) combined with the second-order perturbation technique (SOPT). The ultimate failure load of the LCP is obtained by ply-by-ply failure analysis using the ply discount method combined with the Tsai-Wu failure criterion. The aim is to know the effect of the stacking sequence, crack length, crack angle, location of voids and number of voids on the mean and corresponding COV of the ultimate failure load of LCP is investigated. The results of the ultimate failure load obtained by the present method are in good agreement with the existing experimental and numerical results. It is observed that [0/θ]_s LCPs are very sensitive to the randomness in the crack length, applied load, transverse tensile strength of the laminate and modulus of elasticity of the material, so precise control of these parameters is important. The novelty of the present study is, the stochastic implementation in XFEM for the failure prediction of LCPs containing crack and voids.

• Journal of the Korean Home Economics Association
• /
• v.23 no.2
• /
• pp.55-66
• /
• 1985

This study is intended to compare the quality of housing envirionments between single family house and apartments. To be specific, firstly, it is to be examined as to whether there exists any differences between residents of single family house and those of highrise apartments in terms of their perception of the quality of housing environment. Secondly, the major factors of the perception of the quality of housing environment may be linked to the level of housing satisfaction are to be explored in this study. The perception of the quality housing environment is composed of four factors such as living space, noise, neighbor environment, and structural feature. For the purpose, questionnaires were adinistered to 125 home makers living in single family house and 125 home makers in high-rise apartments in Kwangju. The data were analyzed with factor analysis, analysis of variance, and multiple regression analysis.The following conclusions are derived from the data analysis in thi study: 1) Resjdents of apartments tended to be more satisfied with structural feature of housing unit and less satisfied with noise than those of single family house. There are negligible differences between two housing types in perception of the quality of living space, and neighbor environment. 2) According to the singhle family house group, it is found that structural feature, neighbor environment, and living space predict most of the variance in the level of housing unit satisfaction. It is also turned out that neighbor environment, noise, and structural feature have impact on the level of neighborhood statisfaction. 3) the apartments group shows that structural feature is the only predictor having impact on housing unit satisfaction. It is found that neighbor environment factor predicted the level of neighborhood satisfaction.

• The Korean Journal of Pain
• /
• v.32 no.2
• /
• pp.120-128
• /
• 2019

Background: We aimed to explore the American College of Rheumatology (ACR) 1990 and 2011 fibromyalgia (FM) classification criteria's items and the components of Fibromyalgia Impact Questionnaire (FIQ) to identify features best discriminating FM features. Finally, we developed a combined FM diagnostic (C-FM) model using the FM's key features. Methods: The means and frequency on tender points (TPs), ACR 2011 components and FIQ items were calculated in the FM and non-FM (osteoarthritis [OA] and non-OA) patients. Then, two-step multiple logistic regression analysis was performed to order these variables according to their maximal statistical contribution in predicting group membership. Partial correlations assessed their unique contribution, and two-group discriminant analysis provided a classification table. Using receiver operator characteristic analyses, we determined the sensitivity and specificity of the final model. Results: A total of 172 patients with FM, 75 with OA and 21 with periarthritis or regional pain syndromes were enrolled. Two steps multiple logistic regression analysis identified 8 key features of FM which accounted for 64.8% of variance associated with FM group membership: lateral epicondyle TP with variance percentages (36.9%), neck pain (14.5%), fatigue (4.7%), insomnia (3%), upper back pain (2.2%), shoulder pain (1.5%), gluteal TP (1.2%), and FIQ fatigue (0.9%). The C-FM model demonstrated a 91.4% correct classification rate, 91.9% for sensitivity and 91.7% for specificity. Conclusions: The C-FM model can accurately detect FM patients among other pain disorders. Re-inclusion of TPs along with saving of FM main symptoms in the C-FM model is a unique feature of this model.

• Korean Journal of Health Education and Promotion
• /
• v.6 no.2
• /
• pp.4-22
• /
• 1989

This study aims to explore the relationship between housewives' health KAP level and the physical health of families. The data used in this study are obtained from the Last Evaluation Program of the National Note for Health surveyed in July, 1989. The respondents for this study are 770 housewives residing in Chunan and Buan. The reason why this study focus on KAP level of housewives is to find out whether a housewife as a emotional supporter contributes to the physical health of her families. A housewife gives her families emotional satisfaction insteade of economic satisfaction. So she has the most interest in family health among the members of her family. Therefore, housewife's KAP level will influence her family health. The independent variables chosen for the analysis are the general characteristic variables and KAP level. And the dependent variable is the physical health of families which excluded psychosocial one. This level of family health includes weight for family health and seriouseness of disease. The result of this study was summarized as follows. (1) KAP level was significantly correlated with variables which have mainly the socioeconomic characteristics. The variables were: area of residence, education level occupation, self assessment on wealth, and exposure to mass communication. (2) In the analysis of relationship between the general characteristic variables and family health, family health was significantly correlated with almost all variables. The variables were: Presence of the aged, Health status, Experience in disease, Self assessment on health, No. of families, Occupation, Education level, Self assessment on wealth, Concern on health, and Exposure to mass communication. (3) In the analysis of relationship between family health and KAP level, family health was not significantly correlated with KAP level but. (4) Also in the stepwise regression analysis, the general variables account for about 32.1 percent of the variance in the dependent variable, family health. The variable with the greatest explanatory power was presence of the aged. On the contrary, KAP level explain about 0.4 percent of the variance in the dependent variable. In sum, the study shows that housewives' health KAP level has relatively weak relationship with the physical health of families

• Safety and Health at Work
• /
• v.7 no.4
• /
• pp.307-316
• /
• 2016

Background: Resilience engineering (RE) is a new paradigm that can control incidents and reduce their consequences. Integrated RE includes four new factors-self-organization, teamwork, redundancy, and fault-tolerance-in addition to conventional RE factors. This study aimed to evaluate the impacts of these four factors on RE and determine the most efficient factor in an uncertain environment. Methods: The required data were collected through a questionnaire in a petrochemical plant in June 2013. The questionnaire was completed by 115 respondents including 37 managers and 78 operators. Fuzzy data envelopment analysis was used in different ${\alpha}$-cuts in order to calculate the impact of each factor. Analysis of variance was employed to compare the efficiency score means of the four abovementioned factors. Results: The results showed that as ${\alpha}$ approached 0 and the system became fuzzier (${\alpha}=0.3$ and ${\alpha}=0.1$), teamwork played a significant role and had the highest impact on the resilient system. In contrast, as ${\alpha}$ approached 1 and the fuzzy system went toward a certain mode (${\alpha}=0.9$ and ${\alpha}=1$), redundancy had a vital role in the selected resilient system. Therefore, redundancy and teamwork were the most efficient factors. Conclusion: The approach developed in this study could be used for identifying the most important factors in such environments. The results of this study may help managers to have better understanding of weak and strong points in such industries.