• Geomechanics and Engineering
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• v.32 no.2
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• pp.159-177
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• 2023

In the present work, a simple and refined shear deformation theory is used to analyze the effect of visco-elastic foundation on the buckling response of exponentially-gradient sandwich plates under various boundary conditions. The proposed theory includes indeterminate integral variables kinematic with only four generalized parameters, in which no shear correction factor is used. The visco-Pasternak's foundation is taken into account by adding the influence of damping to the usual foundation model which characterized by the linear Winkler's modulus and Pasternak's foundation modulus. The four governing equations for FGM sandwich plates are derived by employing principle of virtual work. To solve the buckling problem, Galerkin's approach is utilized for FGM sandwich plates for various boundary conditions. The analytical solutions for critical buckling loads of several types of powerly graded sandwich plates resting on visco-Pasternak foundations under various boundary conditions are presented. Some numerical results are presented to indicate the effects of inhomogeneity parameter, elastic foundation type, and damping coefficient of the foundation, on the critical buckling loads.

• International Journal of Aeronautical and Space Sciences
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• v.14 no.2
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• pp.122-132
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• 2013

In this research the development of unstructured grid discretization solution techniques is presented. The purpose is to describe such a conservative discretization scheme applied for experimental validation work. The objective of this paper is to better establish the effects of mesh generation techniques on velocity fields and particle deposition patterns to determine the optimal aerodynamic characteristics. In order to achieve the objective, the mesh surface discretization approaches used the VLA prototype manufacturing tolerance zone of the outer surface. There were 3 schemes for this discretization study implementation. They are solver validation, grid convergence study and surface tolerance study. A solver validation work was implemented for the simple 2D and 3D model to get the optimum solver for the VLA model. A grid convergence study was also conducted with a different growth factor and cell spacing, the amount of mesh can be controlled. With several amount of mesh we can get the converged amount of mesh compared to experimental data. The density around surface model can be calculated by controlling the number of element in every important and sensitive surface area of the model. The solver validation work result provided the optimum solver to employ in the VLA model analysis calculation. The convergence study approach result indicated that the aerodynamic trend characteristic was captured smooth enough compared with the experimental data. During the surface tolerance scheme, it could catch the aerodynamics data of the experiment data. The discretization studies made the validation work more efficient way to achieve the purpose of this paper.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.6
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• pp.4208-4215
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• 2015

Most of the administrative works are executed based on the address. Therefore, spatial information is an essential factor for administrative works. So far, many systems, which apply spatial information to administrative works, have been implemented. However, there is little approach to apply spatial information to road occupation permit works. In this paper, we introduce system implementation plan for applying spatial information to road occupation permit administrative works. System implementation plan includes work analysis, applying scenarios extraction, system function extraction, and datamart construction plans. First, work processes and activities are defined based on the analysis of work handbook. Also, activities are displayed in diagram. Second, scenarios applying spatial information to road occupation permit works are extracted. Third, we derive service functions for system, which realize work processes and applying scenarios. Finally, spatial information datamart construction plan is established. Proposed system implementation plan in this research includes application architecture and part of data architecture. For implementing the system, plan for hardware and software architecture should be studied.

• Steel and Composite Structures
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• v.25 no.3
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• pp.347-360
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• 2017

The goal of this study is to fill this apparent gap in the area about vibration analysis of multiwalled carbon nanotubes (MWCNTs) curved panels by providing 3-D vibration analysis results for functionally graded multiwalled carbon nanotubes (FG-MWCNTs) sandwich structure with power-law distribution of nanotube. The effective material properties of the FG-MWCNT structures are estimated using a modified Halpin-Tsai equation. Modified Halpin-Tsai equation was used to evaluate the Young's modulus of MWCNT/epoxy composite samples by the incorporation of an orientation as well as an exponential shape factor in the equation. The exponential shape factor modifies the Halpin-Tsai equation from expressing a straight line to a nonlinear one in the MWCNTs wt% range considered. Also, the mass density and Poisson's ratio of the MWCNT/phenolic composite are considered based on the rule of mixtures. Parametric studies are carried out to highlight the influence of MWCNT volume fraction in the thickness, different types of CNT distribution, boundary conditions and geometrical parameters on vibrational behavior of FG-MWCNT thick curved panels. Because of using two-dimensional generalized differential quadrature method, the present approach makes possible vibration analysis of cylindrical panels with two opposite axial edges simply supported and arbitrary boundary conditions including Free, Simply supported and Clamped at the curved edges. For an overall comprehension on 3-D vibration analysis of sandwich panel, some mode shape contour plots are reported in this research work.

• Journal of the Korean Society of Costume
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• v.53 no.1
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• pp.67-75
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• 2003

From ancient times. lotus pattern had esthetic factor and symbolic factor. Lotus pattern was introduced to China, and it was grafted together with Chinese peculiar culture symbol system, thereafter it has changed and developed. The Chinese taking a serious view meaning that things include, and they frequently use several lucky omen patterns in their everyday life. In this study, I investigated laying stress on symbolism about Lotus patterns of China lucky omen patterns, and I wanted to present possibility that can approach to Chinese culture in new angle. Through result of this study, symbol of Lotus patterns can divide two directions. First, symbol by natural properties of lotus are same as following. 1. Lotus grows in the mud, but it is uncontaminated - clearness and uprightness, 2. Root, branches, loaves and flowers are vegetative together, and all of basis and branches are exuberant. - plenty, 3. Bear fruit simultaneously with blooming, and it is procreant. - fecundity and many descendants. Symbol that use same pronunciation and intention are same as following. 1. 'Lian(연)'-'Lian(연)' : repeatability, continuance, plenty and intercommunicate, 2. 'Lian(연)'-'Lian(염)': integrity, 3. 'He (하)'-'He(화)' : peace, harmony and combination, 4. 'He(하)'-'He(하)' : clear river, 5.'He(하)'-'He(하)' ; all work goes well. When the Chinese use lotus patterns in lucky omen patterns, same pronunciation and pitch of Chinese language more prominent than natural properties or the image of Buddhism. I guess that it cause praying individual's peace and happiness more serious than philosophical meaning or symbol that base in Buddhism for ordinary people.

• The Journal of Korean Physical Therapy
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• v.23 no.4
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• pp.7-13
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• 2011

Purpose: The purpose of this article is to identify whether the physical therapists perceive the important factors influencing the motor development in children with cerebral palsy differently. Methods: Study participants included 58 pediatric physical therapists. They were recruited from the internet communities for physical therapists. The data was collected through a web-based questionnaire using Google Documents tool. Questionnaire was focused on the importance (10-point scale) of each factor influencing the motor development in children with cerebral palsy. The mean scale of each factor was compared by itself and according to the participants' career characteristics. Results: The personality characteristics received the least importance rating (6.77) in comparison with other domains (healthcare service: 7.70, family ecology: 7.53, secondary impairment: 7.53, primary impairment: 7.45). In the detailed items, home exercise (8.33) received the highest mean importance rating, while sociability (6.03) received the lowest mean importance rating. Comparing the importance of factors by the type of work institution, subjects working in the welfare institutions perceived the contextual factors (personality characteristics, family ecology, healthcare service) as more important than those working in the medical institutions. Conclusion: The authorsuggests that pediatric physical therapists should try to have an identical approach by reaching a consensus. Also, the support for family-centered service to children with cerebral palsy should be strengthened.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.24 no.3
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• pp.393-403
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• 2014

Objectives: Korean Occupational Safety and Health Agency(KOSHA) intended to provide guidance to respirator program administrators on respirator selection. The purpose of this project is to suggest a preliminary respirator selection guide(PRSG) for the final guidance certified by KOSHA for the correct selection of respirators in the workplace. Materials: This PRSG was made on the based of current status of respirator usage including respirators available in Korea, foreign documents search and so on. PRSG was partially modified NIOSH pocket guide to chemical hazards, 3M Respirator Protection Resource Guide(RPRG) and OSHA Assigned Protection Factor(APF) rulemaking. Results: Respirators for chemicals having Korean Occupational Exposure Limits(KOELs) can be recommended in PRSG. For the others chemicals that have no KOELs, PRSG tells you what respirators you can select, using a simple step-by-step approach after health hazard assessment like HSE procedure. Conclusions: PRSG helps you to decide the right level of protection for a given hazardous substance and how to select the right respirators. PRSG is thus expected to reduce significant misuses of respirators for the work environment.

• Steel and Composite Structures
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• v.23 no.6
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• pp.657-668
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• 2017

In the most of previous studies, researchers have restricted their own studies to consider the effect of single walled carbon nanotubes as a reinforcement on the vibrational behavior of structures. In the present work, free vibration characteristics of functionally graded annular plates reinforced by multi-walled carbon nanotubes resting on Pasternak foundation are presented. The response of the elastic medium is formulated by the Winkler/Pasternak model. Modified Halpin-Tsai equation was used to evaluate the Young's modulus of the multi-walled carbon nanotube/epoxy composite samples by the incorporation of an orientation as well as an exponential shape factor in the equation. The exponential shape factor modifies the Halpin-Tsai equation from expressing a straight line to a nonlinear one in the multi-walled carbon nanotubes wt% range considered. The 2-D generalized differential quadrature method as an efficient and accurate numerical tool is used to discretize the equations of motion and to implement the various boundary conditions. The effects of two-parameter elastic foundation modulus, geometrical and material parameters together with the boundary conditions on the frequency parameters of the plates are investigated. This study serves as a benchmark for assessing the validity of numerical methods or two-dimensional theories used to analysis of annular plates.

• Steel and Composite Structures
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• v.25 no.6
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• pp.639-648
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• 2017

Fracture energy values KV have been measured on cast steel, used in the container manufacture, by instrumented Charpy impact testing. This material has a large ductility on the upper transition region at $+20^{\circ}C$ and a ductile tearing with an expended plasticity before a brittle fracture on the lower transition region at $-20^{\circ}C$. To assess the fracture toughness of this material we use, the $K_{IC}$-KV correlations to measure the critical stress intensity factor $K_{IC}$ on the lower transition region and the dynamic force - displacement curves to measure the critical fracture toughness $J{\rho}_C$, the essential work of fracture ${\Gamma}_e$ on the upper transition region. It is found, using the $K_{IC}$-KV correlations, that the critical stress intensity factor $K_{IC}$ remains significant, on the lower transition region, which indicating that our testing material preserves his ductility at low temperature and it is apt to be used as a container's material. It is, also, found that the $J_{\rho}-{\rho}$ energetic criterion, used on the upper transition region, gives a good evaluation of the fracture toughness closest to those found in the literature. Finally, we show, by using the ${\Gamma}_e-K_{IC}$ relation, on the lower transition region, that the essential work of fracture is not suitable for the toughness measurement because the strong scatter of the experimental data. To complete this study by a numerical approach we used the ANSYS code to determine the critical fracture toughness $J_{ANSYS}$ on the upper transition region.

• Safety and Health at Work
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• v.11 no.4
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• pp.526-532
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• 2020

Background: The high incidence of work-related diseases and injuries among day-laborers and workers with no legal contracts (informal workers) has received the attention of the Thai authorities. Workers' low occupational health literacy (OHL) has been reasoned as one contributing factor. Absence of a valid tool has prevented assessment of informal workers' OHL. The aim of this study was to create a valid and reliable Occupational Health Literacy Scale within the context of Thai working culture (TOHLS-IF). Methods: This study used the mixed method approach to develop TOHLS-IF. Questions were generated using in-depth interviews and an extensive review of the literature. Experts' assessment confirmed the content validity of TOHLS-IF. The scales of its psychometric properties were assessed in a sample of 400 informal workers using cluster random sampling. Results: The final version of the TOHLS-IF comprises 38 items within 4 dimensions: Ability to Gain Access, Understanding, Evaluation, and Use of occupational health and safety information. Factor analysis identified items explaining 50.22% of the total variance. The final confirmatory analysis confirmed the model estimates were satisfactory for the construct. TOHLS-IF demonstrated a high internal consistency and satisfactory reliability (Cronbach's alpha = .98). Conclusion: The TOHLS-IF is a valid and reliable instrument to assess informal workers' OHL. The structural dimensions of this instrument are based on the concept of health literacy and Thai culture. Thai health professionals are encouraged to benefit from this instrument to assess their workers' OHL and apply findings as guidelines for effective occupational health and safety interventions.