• Journal of Korean Society of Transportation
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• v.19 no.1
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• pp.17-28
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• 2001

The purpose of this study is to analyze logistics cost of transportation systems on EC(electronic commerce) between company and consumer. Transportation system in logistics is classified by three types on EC. The first type is the direct delivery from supply factory to consumers(type I). The second type is the delivery through distribution center in each area by owner logistics company (type II). The third type is the commission of delivery to the third party logistics company(type III). The logistics of EC has various service characteristics such as dealing with small quantity, various goods, and high frequency. This study assumes that all day's order is delivered on a next day. The logistics cost function is calculated according to the number of orders, delivery distance, transport quantify. and allocated freight trucks for daily order of the subject zone. The logistics cost changes according to the daily order characteristics. Therefore it is simulated to analyze the logistics cost change that considers the type of transportation's order characteristics. As a result of analysis, if the number of order is less than 10 and the quantify of each order is less than 10kg, type III has an advantage over the others And if the number of order is more than 10 and the quantity of each order is more than 10kg, type I has an advantage in the same zone and type II has an advantage in the other zones. This study is limited on the actual application because this study doesn't consider logistics infra of supply company and transport service time. If further study that considers these factors is implemented, it can estimate more accurate logistics cost on EC and propose an efficient freight transport alternatives to the company. This study attributes to estimate the logistics cost change over the frequency of daily order, the quantify of supply goods, and the transport distance on EC.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.11
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• pp.5542-5550
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• 2012

Third-order shear deformation theory is reformulated using the nonlocal elasticity of Eringen. The equation of equilibrium of the nonlocal elasticity are derived. This theory has ability to capture the both small scale effects and quadratic variation of shear strain through the plate thickness. Navier's method has been used to solve the governing equations for all edges simply supported boundary conditions. Analytical solutions of buckling of nano-scale plates are presented using this theory to illustrate the effect of nonlocal theory on buckling load of the nano-scale plates. The relations between nonlocal third-order and local theories are discussed by numerical results. Further, effects of (i) length (ii) nonlocal parameter, (iii) aspect ratio and (iv) mode number on nondimensional buckling load are studied. In order to validate the present solutions, the reference solutions are used and discussed. The present results of nano-scale plates using the nonlocal theory can provide a useful benchmark to check the accuracy of related numerical solutions.

• Journal of Fisheries and Marine Sciences Education
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• v.27 no.5
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• pp.1436-1446
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• 2015

This study aims to understand how scuba diving instructors' expertise, instructor reliability and instruction efficiency are related to each other. In order to achieve the research goal, the study used a multi-stage stratified cluster sampling method and collected valid samples from 400 individuals at age of 20 and older who were scuba diving in scuba diving clubs in Busan, Gyeongnam, Gyeongbuk, Jeonnam and Jeonbuk. The 400 valid samples were applied to the data analysis. The study used SPSS 21.0 for processing the gathered data via a frequency analysis, a reliability analysis and a correlation analysis and in order to verify the hypotheses, the study applied AMOS 21.0 and conducted a confirmatory factor analysis and a structure equation model analysis. Findings that the study had extracted are summarized as follows. First, the study confirmed that the scuba diving instructors' expertise has a positive effect on the instructor reliability. Second, the scuba diving instructors' expertise was reported to positively influence the instruction efficiency. Third, the results revealed that the scuba diving club members' reliability in the instructors has a positive influence on the instruction efficiency.

• International Journal of Advanced Culture Technology
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• v.11 no.4
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• pp.244-254
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• 2023

The purpose of the study is to determine the relationship between leisure sports activities among the elderly, wellness awareness, perceived freedom, and subjective well-being. In order to achieve the purpose of this study, the study subjects were selected as the population aged 65 or older who lived in the Gwangju Metropolitan City area in 2022 and engaged in leisure sports activities. As for the sampling method, samples were extracted using cluster random sampling. A total of 300 people, 150 male and 150 female, were sampled. The survey tool was modified and supplemented according to this study based on the questionnaire that had been verified for reliability and validity in previous studies, and all questionnaire items were composed of a 5-point scale. The statistical analysis used for data analysis was frequency analysis, exploratory factor analysis, reliability analysis, and multiple regression analysis using SPSS Windows 21.0 Version. First, it was found that the wellness perception of the elderly partially affects the perceived sense of freedom. Second, it was found that the wellness perception of the elderly partially affects psychological happiness. Third, the elderly's perceived sense of freedom was found to affect their subjective well-being. Considering these research results, in order to effectively improve the quality of life in old age, it is important to promote physical, mental, emotional, and social relationships through nature-friendly sports activities to improve subjective life motivation, satisfaction, and happiness. It can be said that it increases the sense of well-being.

• Steel and Composite Structures
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• v.24 no.2
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• pp.151-176
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• 2017

This paper deals with general equations of motion for free vibration analysis response of thick three-layer doubly curved sandwich panels (DCSP) under simply supported boundary conditions (BCs) using higher order shear deformation theory. In this model, the face sheets are orthotropic laminated composite that follow the first order shear deformation theory (FSDT) based on Rissners-Mindlin (RM) kinematics field. The core is made of orthotropic material and its in-plane transverse displacements are modeled using the third order of the Taylor's series extension. It provides the potentiality for considering both compressible and incompressible cores. To find these equations and boundary conditions, Hamilton's principle is used. Also, the effect of trapezoidal shape factor for cross-section of curved panel element ($1{\pm}z/R$) is considered. The natural frequency parameters of DCSP are obtained using Galerkin Method. Convergence studies are performed with the appropriate formulas in general form for three-layer sandwich plate, cylindrical and spherical shells (both deep and shallow). The influences of core stiffness, ratio of core to face sheets thickness and radii of curvatures are investigated. Finally, for the first time, an optimum range for the core to face sheet stiffness ratio by considering the existence of in-plane stress which significantly affects the natural frequencies of DCSP are presented.

• The Research Journal of the Costume Culture
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• v.26 no.6
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• pp.872-887
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• 2018

This study aims to identify the differences between Korean and Chinese and males and females in terms of female image preferences. The survey was conducted for 1 month targeting male and female Korean and Chinese subjects. Among the 350 completed questionnaires, 309 were used for analysis. For the analysis, 11 female images were chosen based on theoretical study, then a t-test and a paired t-test were carried out using SPSS 19.0. The results of this study are as follows: First, differences in female image preferences were observed to depend on nationality and gender. Koreans prefer urban images while Chinese prefer cute, intelligent, and sexy images. Second, males prefer innocent or sexy images, while females prefer sophisticated images. Third, Korean males prefer innocent, active, sophisticated, gentle, cute, sexy, urban, natural, intelligent, spectacular, and neutral images in order. Chinese males prefer gentle, innocent, sexy, active, sophisticated, intelligent, cute, natural, urban, spectacular, and neutral images in order. Fourth, Korean females prefer sophisticated, gentle, urban, natural, intelligent, innocent, active, sexy, cute, spectacular, and neutral images in order. Chines females prefer sophisticated, intelligent, cute, gentle, innocent, active, natural, sexy, urban, spectacular, and neutral images in order. Using these results, it will be possible to design marketing strategies for global consumers.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.4
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• pp.53-59
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• 2022

In this study, an enhanced first-order shear deformation theory is proposed to efficiently and accurately predict the thermo-mechanical-viscoelastic coupled behavior of laminated composite structures. To this end, transverse shearstress and displacement fields are independently assumed, and the strain-energy relationship between these fields issystematically established using the mixed variational theorem (MVT). In MVT, the transverse shear stress fields are obtained from the third-order zigzag model, whereas the displacement fields of the conventional first-order model are considered to amplify the benefits of numerical efficiency. Additionally, a transverse displacement field with a smooth parabolic distribution is introduced to accurately predict the thermal behavior of composite structures. Furthermore, the concept of Laplace transformation is newly employed to simplify the viscoelastic problem, similar to the linear-elastic problem. To demonstrate the performance of the proposed theory, the numerical results obtained herein were compared with those available in the literature.

• Journal of Korean Medical Ki-Gong Academy
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• v.10 no.1
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• pp.130-157
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• 2007

The purpose of this research is to seek for efficient health maintenance device and to suggest desirable daily habit, based on the inquiry on interrelationship between workers' daily lives and their heartbeat change level. The paper survey about general features, case history and daily habits was conducted on workers during medical examination in Jeollabukdo, and examined their change of heartbeat as well. The results of research deducted from data analysis are as follows; 1. There found very positive interrelations between time-domain analysis and frequency-domain analysis, and MHR and LF/HF ratio had negative connection with other analyses. 2. The recipient showed high time-domain analysis when they are younger, have worked shorter or have spouse, and it contributes to stable sympathetic nerve and parasympathetic nerve as it stimulates autonomic nervous system. 3. According to the result of frequency-domain analysis, recipients showed higher TP and LF when they are younger, and the highest HF when they are under 34.The level of VLF was higher for university graduates than the ones who finished high school. The recipients showed higher TP and HF when they don't have spouse, and lower TP, LF and HF when they have worked longer. 4. The level of RMSSD and TSRD was high for the people who don't have case history, and HF was high when they don't have any disease in progress. 5. According to the result concerning correlation of daily habits with time-domain analysis and frequency-domain analysis, cigarette, alcohol and sleeping hours don't affect heartbeat change, but the ones who regularly workout showed higher result in every analysis. It shows that the autonomic nervous system of recipients who regularly exercise response more actively. The result mentioned above suggests that the change of heartbeat is a direct index which shows the change of autonomic nervous system, and it depends on the exercise the most. Thus, workout is proved to be the best method in order for workers to take care of their health.

• Structural Engineering and Mechanics
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• v.62 no.1
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• pp.1-9
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• 2017

This paper describes laboratory tests carried out to evaluate the influence of class F fly ash (FA) on fracture toughness of plain concretes, specified at the third model fracture. Composites with the additives of: 0%, 20% and 30% siliceous FA were analysed. Fracture toughness tests were performed on axial torsional machine MTS 809 Axial/Torsional Test System, using the cylindrical specimens with dimensions of 150/300 mm, having an initial circumferential notch made in the half-height of cylinders. The studies examined effect of FA additive on the critical stress intensity factor $K_{IIIc}$. In order to determine the fracture toughness $K_{IIIc}$ a special device was manufactured.The analysis of the results revealed that a 20% FA additive causes increase in $K_{IIIc}$, while a 30% FA additive causes decrease in fracture toughness. Furthermore, it was observed that the results obtained during fracture toughness tests are convergent with the values of the compression strength tests.

• Journal of the Korean Society of Safety
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• v.8 no.4
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• pp.183-188
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• 1993

Anthropometric characteristics and considerations of sex differences are essential for the correct design of ergonomic work spaces. This paper is concerned with longitudinal study on the physical growth in Korean youth. Three hundred eighty-seven subjects were selected from third year students of high schools, and their records on physical examination during the last twelve years were surveyed by longitudinal method. For boys and girls, this study investigated the anthropometric characteristics of physical structure and the shape of physical growth. The result showed that the physical growth spurt of girl occurred earlier than that of boy. Also, by regression analysis, the third-order polynomial function was suitable for the growth curves of stature and weight, and there were significant sex differences in the fitted curves.