• Journal of Korean Society of Transportation
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• v.20 no.1
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• pp.121-130
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• 2002

Purpose of this paper is proposing technical evaluation method for safety on two-lane rural highways, this method can contribute to an establishment of the safety evaluation criteria and eventually contribute to the highway safety. In this study, accident data and field data(grade, radius, speed factor) are collected and are analyzed. And new technical evaluation method is proposed by problem in review of existent methods and analysis result. Property of new method is verified by comparing with existent one. Following are results of this study. 1) Proposed technical evaluation method is Proposed by using difference of speed variance and difference of acceleration. 2) In range of field survey, proposed method is more proper than existent one by comparing. 3) Headways under 6 second affect speed of next vehicle. 4) A point with the lowest speed in curve is placed about 35m from the beginning point. 5) Correlation of speed variance and severity of highway(EPDO) is statistically significant. For using proposed method, more tests are needed on other locations with various geometries. Moreover, advanced study is needed about classifying and giving the weight of each criterion.

• The Korean Journal of Applied Statistics
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• v.19 no.2
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• pp.231-240
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• 2006

It is well understood that a paired comparison (paired t test) provides better precision than a group comparison (two-sample t test), when the pairing is effective (the variation within a pair is small). However, when the variation among the pairs is sufficiently small, the group comparison is likely to yield a better result. To get a statistical explanation of this, we examine the two methods through an analogy to one-way and two-way analysis of variance. We introduce a new measure, R statistic, which is the ratio of their confidence interval lengths, as a quantitative criterion for comparing the two methods. The distribution of the Rf statistic is described by t and F distribution functions. Through this characterization, we show that the paired comparison can be better than group comparison when the variation among the pairs is statistically significantly large.

• Journal of Welding and Joining
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• v.20 no.3
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• pp.122-128
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• 2002

The laser welding in the automotive industries has been used widely for the butt joint of blank sheets rather than the lap joint of automotive body panels. But as a substitute far the spot welding of automotive body panels, the so called three dimensional laser welding will be important far the body panel engineers. Specially the laser welding of body panels with a smooth weld line is applied increasingly, for example, to the side panels. So far, some criteria of the laser weld quality was suggested by in-house regulations or national standards from experiences and/or rule of thumbs. In the manufacturing places, a go or no-go criterion is adopted because of the simplicity or a lack of rational criteria. It is true specially for the selection of the process parameters, which gives the basic causes for the good quality of laser welds. In this study, the effects of joint combination, gap and welding speed on the lap joint $CO_2$ laser welding of two mild steel sheets with different thicknesses are obtained through a $2{\times}3{\times}7$ factorial experiment. The results of the weld quality are statistically analysed using analysis of variance (ANOVA) and compared between two characteristic zones, which are separated by the type of sectional shapes and the level of input energy per volume. The thickness combinations are 0.8mm/1.2mm, 1.2mm/0.8mm of mild steel sheets. The welding speed covers from the deep penetration to the partial penetration. The gap size has three levels of no-gap, 0.16m, and 0.26mm. The bead width, penetration depth and input energy per volume are measured and used as the weld quality criteria.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.22 no.1
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• pp.65-80
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• 2023

In this study, a classification analysis was performed based on the type of traffic situation. The purpose was to derive the major variable factors that could represent the traffic situation. The TTI(Travel Time Index) was used as a criterion for determining traffic conditions, and analysis was performed using data generally detected by the Vehicle Detecting System(VDS). First, the major factors influencing the traffic situation were selected through factor analysis, and traffic conditions were clustered through a cluster analysis of the major factors. After that, variance analysis for each cluster was performed based on the TTI, and similar clusters were merged to categorize the type of traffic situation. The analysis derived, the maximum queue length and occupancy as major factors that could represent the traffic situation. Through this study, it is expected that efficient management of traffic congestion would be possible by just concentrating on the main variable factors that affect the traffic situation.

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

• Korean Security Journal
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• no.61
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• pp.235-254
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• 2019

This study identifies a factor structure regarding the criterion of terror awareness by using confirmatory factor analysis. The study provides information whether the criterion fits in the analysis of terror awareness in Korea or not. Data of 176 public officials working at the National Assembly collected in 「Study on the Improvement of Security in the National Assembly Building」(Choi O-Ho and others, 2016) was used in the analysis. Study results showed the fit statistics of 3 questions regarding concern in terror, 5 questions regarding cognition of terror occurrence, 3 questions regarding countermeasure of terror, and 3 questions regarding equipments against terror satisfied the standard. Also, standard regression coefficient exceeded the standard and was shown to be fit. Concern in terror, as a latent variable, was below the standard value of average variance extracted. However, focused validity was secured by obtaining other values fit. This study proceeded distinct validation test to supplement data. The test results showed that the criterion level was fit. Thus, further survey should include questions that are appropriate to measure the awareness of terror based not only on theories and previous studies but also on questions of terror awareness tested in this study. Such development in surveys will support the means of data measurement.

• Research in Community and Public Health Nursing
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• v.26 no.4
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• pp.330-341
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• 2015

Purpose: This study developed a self-report measure for easy assessing of the health literacy of Asian immigrant women in South Korea. Methods: After a literature review, focus group interviews, and content validity evaluation, 14 preliminary items were generated. These were translated into Chinese, Vietnamese, and English. Data were collected from 229 Asian immigrant women. Validity and reliability tests were conducted. Results: Factor analysis yielded final 10 items in three factors: primary functional and interactive health literacy, secondary functional and interactive health literacy, and critical health literacy, which explained 61.90% of the total variance of health literacy. In known-group comparisons, health literacy was significantly lower in recent immigrants, those with a low education level, and those with low Korean language proficiency. For convergent validity, health literacy was positively associated with health specific self-efficacy and maternal health knowledge. For criterion-related validity, health literacy was positively associated with the REALM-SF. The overall reliability coefficient (Cronbach's ${\alpha}$) of the instrument was .773. Conclusion: The Health Literacy Assessment Scale for Asian Immigrant Women (HLAS) represents a multidimensional construct which encompasses functional, interactive, and critical health literacy. This self-report HLAS can be a useful and convenient method for appraising the health literacy of Asian immigrant women.

• Journal of Korean Academy of Nursing
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• v.41 no.3
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• pp.313-324
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• 2011

Purpose: The study was done to develop a dignified dying scale for Korean adults. Methods: The process included construction of a conceptual framework, generation of initial items, verification of content validity, selection of secondary items, preliminary study, and extraction of final items. The participants were 428 adults who lived in one of 3 Korean metropolitan cities: Seoul, Daegu, and Busan. Item analysis, factor analysis, criterion related validity, and internal consistency were used to analyze the data. Data collection was done from March to June 2010. Results: Thirty items were selected for the final scale, and categorized into 5 factors explaining 54.5% of the total variance. The factors were labeled as maintaining emotional comfort (10 items), arranging social relationship (9 items), avoiding suffering (3 items), maintaining autonomous decision making (4 items), and role preservation (4 items). The scores for the scale were significantly correlated with personal meanings of death scale. Cronbach's alpha coefficient for the 30 items was .92. Conclusion: The above findings indicate that the dignified dying scale has a good validity and reliability when used with Korean adults.

• Journal of Korean Academy of Nursing
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• v.44 no.6
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• pp.630-638
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• 2014

Purpose: The purpose of this study was to develop a scale to evaluate stress in elderly patients with coronary artery diseases (CAD) and to examine validity and reliability of the scale. Methods: The development process for the preliminary scale included construction of a conceptual framework and initial items, verification of content analysis, sentence correction, and pilot study. This study was conducted using a questionnaire survey with one-to-one interviews during January and February, 2012. Participants were 240 elderly patients with CAD. Data were analyzed using item analysis, factor analysis, criterion related validity, and internal consistency. Results: The developed scale consisted of 32 items and 6 factors - aging and disease (7 items), family relations (5 items), anxiety and withdrawal (9 items), management of daily living (3 items), compliance of medical regimen (4 items), poverty and finance (4 items), and explained 68.5% of total variance. The scale had significantly positive correlation with the Korean Perceived Stress Scale (KPSS). Cronbach's alpha was .96, and Guttman split half coefficient was .91. Conclusion: Results indicate that the Stress Scale for Elderly Patients with CAD has validity and reliability, and is a suitable scale in health care settings to assess stress in elderly patients with CAD.

• The Journal of Korean Academic Society of Nursing Education
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• v.23 no.2
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• pp.165-174
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• 2017

Purpose: This study was done to develop and to evaluate an integrative palliative care scale for cancer patients. Methods: The process included construction of a conceptual framework, generation of initial items, verification of content validity, selection of secondary items, preliminary study, and extraction of final items. The participants were 173 cancer patients in Daegu and Gyeongbuk. Item analysis, factor analysis, criterion related validity, and internal consistency were used to analyze the data. Results: Eighteen items were selected for the final scale, and categorized into 3 factors explaining 58.3% of total variance. The factors were labeled as social/environmental palliative care (9 items), psychological palliative care (4 items), and physical palliative care (3 items), and spiritually palliative care (2 items). The scores for the scale were significantly correlated with the quality of life of cancer patients. Cronbach's alpha coefficient for the 18 items was .88. Conclusion: The above findings indicate that the integrative palliative care scale has good validity and reliability when used for cancer patients.