• International Journal of Highway Engineering
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• 제17권3호
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• pp.117-124
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• 2015

PURPOSES : The purpose of this study is to verify traffic accident injury severity factors for elderly drivers and the relative relationship of these factors. METHODS : To verify the complicated relationship among traffic accident injury severity factors, this study employed a structural equation model (SEM). To develop the SEM structure, only the severity of human injuries was considered; moreover, the observed variables were selected through confirmatory factor analysis (CFA). The number of fatalities, serious injuries, moderate injuries, and minor injuries were selected for observed variables of severity. For latent variables, the accident situation, environment, and vehicle and driver factors were respectively defined. Seven observed variables were selected among the latent variables. RESULTS : This study showed that the vehicle and driver factor was the most influential factor for accident severity among the latent factors. For the observed variable, the type of vehicle, type of accident, and status of day or night for each latent variable were the most relative observed variables for the accident severity factor. To verify the validity of the SEM, several model fitting methods, including ${\chi}^2/df$, GFI, AGFI, CFI, and others, were applied, and the model produced meaningful results. CONCLUSIONS : Based on an analysis of results of traffic accident injury severity for elderly drivers, the vehicle and driver factor was the most influential one for injury severity. Therefore, education tailored to elderly drivers is needed to improve driving behavior of elderly driver.

• Journal of the Korean Society of Safety
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• 제36권3호
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• pp.60-65
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• 2021

Human error is often in part in the cause of accidents and the result of various factors in an organization. Accidents should be investigated to elucidate all causes. Therefore, to reduce accidents, it is necessary to identify which factors affect human error within the organization. In this study, five groups of influencing factors on human error were selected using previousresearch, and operational definitions were made based on them. In addition, a questionnaire for measuring latent variables by operational definition was developed as an observation variable, and responses were received from employees of chemical companies in Ulsan. Based on SEM (structural equation modeling) analysis, 1) confirmatory factor analysis of variables in the human error model, 2) reliability and validity of latent variables, 3) correlations among latent variables, 4) influencing coefficients among influence factors, and 5) the verification results of the paths that these influencing factors have on human error are introduced in this study.

• Journal of Aerospace System Engineering
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• 제3권2호
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• pp.1-11
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• 2009

A structural modelling for study on dynamic characteristics of tapered composite aircraft wings in the form of thin-walled beam is presented. The proposed structural model includes effects of transverse shear flexibility exhibited by the advanced composite materials and warping restraint characterizing elastic anisotropy and induced structural couplings. The complex effects of these factors could have a role in more efficient analysis on those structural models.

• Journal of Welding and Joining
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• 제30권6호
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• pp.80-85
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• 2012

Fatigue cracks in structural components are the most common cause of structural failure when exposed to fatigue loading. In this respect, fatigue crack detection and structural health assessment are very important. Currently, various smart materials are used for detecting fatigue crack and measurement of SIFs(Stress Intensity Factors). So, this paper presented a measurement of SIFs using MFC(Micro Fiber Composite) sensor which is the one of the smart material. MFC sensor is more flexible, durable and reliable than other smart materials. The SIFs of Mode I(K I) as well as Mode II(K II) based on the piezoelectric constitutive law and fracture mechanics are calculated. In this study, the SIF values measured by MFC sensors are compared with the theoretical results.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 한국전산구조공학회 2004년도 가을 학술발표회 논문집
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• pp.517-526
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• 2004

In the resent years, the early evaluation of concrete quality, construction and maintenance has been considered as all is of major concern due to the increase of loading and the degradation of structures related with time. This paper presents evaluation of structural safety performance using measured data of construction, on the basis of a field measurements for the prevention of unreliable concrete works. Measurements analyzed in this paper are early quality condition and performance assessment, serviceability performance by cracks and deflection, rating performance by loading, durability performance by chloride attack and carbonation. Thus, a quantitative assessment model of resistance capacity was developed here to meet the requirement for deteriorated concrete structures. The model focuses on damage mechanical of concrete structures deteriorated by initial damage factors for concrete quality and environment factors such as chloride and carbonation attacks. These results could provide useful information for concrete structures interested in design, construction and maintenance.

• Membrane and Water Treatment
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• 제10권6호
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• pp.417-429
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• 2019

Poly Sulfone nanofibers were electrospun to fabricate membranes of different characteristics. To fabricate the fiber mats, polymer concentration, flowrate, and current density were determined as the most influencing factors affecting the overall performance of the membranes and studied through Response Surface Methodology. The Box-Behnken Design method (three factors at three levels) was used to design, analyze, and optimize the parameters to achieve the best possible performance of the electrospun membranes in forward osmosis process. Also, internal concentration polarization that characterizes the efficiency of the forward osmosis membranes was determined to better assess the overall performance of the fabricated electrospun membranes. Water flux to reverse salt flux was considered as the main response to assess the performance of the membranes. As confirmed experimentally, best membrane performance with the minimal structural parameter value could be achieved when predicted optimal values were used to fabricate the membranes through electrospinning process.

• Korean Journal of Adult Nursing
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• 제16권3호
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• pp.355-365
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• 2004

Purpose: The aims of this study were to develope a structural model of health insensitivity and to verify the model of health insensitivity. Method: There were three theoretical variables in the hypothetical model. The endogenous variable was health insensitivity which is a concept including bluntness of health risk perception and unhealthy behavior. The exogenous variables were composed of personal factors and socio-cultural factors. In personal factors, neuroticism, external health locus of control, blunting style of information-seeking, deficit of self-efficacy, knowledge deficit related to health, health-related experience, age and education were included. Whereas socio-cultural factors include perceived group size of unhealthy behavior and stereotypes of unhealthy behavior. Result: Personal factors and sociocultural factors were significant in explanation of the health insensitivity. Relationship between personal factors and sociocultural factors was significant, too. However, the optimistic bias as part of health insensitivity was not supported by these data. GFI, AGFI and PGFI were .95, .92, .65, respectively. Therefore, this model was verified to be a good fit to the data and parsimonious. Conclusion: Nursing to change unhealthy behavior has focused on personal factors rather than sociocultural factors. Based on this result, however, the sociocultural factors should be considered as well.

• Journal of the Computational Structural Engineering Institute of Korea
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• 제15권2호
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• pp.219-235
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• 2002

This paper deals with parametric studies of the structural response of underground LNG storage tanks according to change in design conditions. In the design of underground LNG storage tank, it is requited to determine the optimal tank shape and dimension to represent a more improved structural behavior under many loading conditions and load combinations. Consequently, main factors which affect to the structural response of LNG storage tanks from planning and design up to maintenance, are investigated, and the differences in structural behavior due to those factors are analyzed. On the basis of the obtained results item parametric studies, a guideline for a more reasonable design is introduced.

• Journal of Korean Academy of Nursing
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• 제42권5호
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• pp.699-708
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• 2012

Purpose: This study was designed to test structural equation modeling of the quality of life of pre-dialysis patients, in order to provide guidelines for the development of interventions and strategies to improve the quality of life of patients with Chronic Kidney Disease (CKD). Methods: Participants were patients who visited the nephrology outpatient department of a tertiary hospital located in Seoul. Data on demographic factors, social support, nutritional status, physical factors and biobehavioral factors and quality of life were collected between March 4 and March 31, 2011. Results: In the final analysis 208 patients were included. Of the patients 42% were in a malnourished state. Anxious or depressed patients accounted for 62.0%, 72.6%, respectively. Model fit indices for the hypothetical model were in good agreement with the recommended levels (GFI=.94 and CFI=.99). Quality of life in pre-dialysis patients with CKD was significantly affected by demographic factors, social support, nutritional status, physical factors and biobehavioral factors. Biobehavioral factors had the strongest and most direct influence on quality of life of patients with CKD. Conclusion: In order to improve the quality of life in pre-dialysis patients with CKD, comprehensive interventions are necessary to assess and manage biobehavioral factors, physical factors and nutritional status.

• International Journal of Highway Engineering
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• 제14권6호
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• pp.121-129
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• 2012

PURPOSES : Traffic accidents at intersections have been increased annually so that it is required to examine the causations to reduce the accidents. However, the current existing accident models were developed mainly with non-linear regression models such as Poisson methods. These non-linear regression methods lack to reveal complicated causations for traffic accidents, though they are right choices to study randomness and non-linearity of accidents. Therefore, to reveal the complicated causations of traffic accidents, this study used structural equation methods(SEM). METHODS : SEM used in this study is a statistical technique for estimating causal relations using a combination of statistical data and qualitative causal assumptions. SEM allow exploratory modeling, meaning they are suited to theory development. The method is tested against the obtained measurement data to determine how well the model fits the data. Among the strengths of SEM is the ability to construct latent variables: variables which are not measured directly, but are estimated in the model from several measured variables. This allows the modeler to explicitly capture the unreliability of measurement in the model, which allows the structural relations between latent variables to be accurately estimated. RESULTS : The study results showed that causal factors could be grouped into 3. Factor 1 includes traffic variables, and Factor 2 contains turning traffic variables. Factor 3 consists of other road element variables such as speed limits or signal cycles. CONCLUSIONS : Non-linear regression models can be used to develop accident predictions models. However, they lack to estimate causal factors, because they select only few significant variables to raise the accuracy of the model performance. Compared to the regressions, SEM has merits to estimate causal factors affecting accidents, because it allows the structural relations between latent variables. Therefore, this study used SEM to estimate causal factors affecting accident at urban signalized intersections.