• Structural Engineering and Mechanics
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• v.64 no.1
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• pp.121-133
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• 2017

This paper proposes an analytical solution method for free vibration of curved functionally graded (FG) nonlocal beam supposed to different thermal loadings, by considering porosity distribution via nonlocal elasticity theory for the first time. Material properties of curved FG beam are assumed to be temperature-dependent. Thermo-mechanical properties of porous FG curved beam are supposed to vary through the thickness direction of beam and are assumed to be temperature-dependent. Since variation of pores along the thickness direction influences the mechanical and physical properties, porosity play a key role in the mechanical response of curved FG structures. The rule of power-law is modified to consider influence of porosity according to even distribution. The governing equations of curved FG porous nanobeam under temperature field are derived via the energy method based on Timoshenko beam theory. An analytical Navier solution procedure is used to achieve the natural frequencies of porous FG curved nanobeam supposed to thermal loadings with simply supported boundary condition. The results for simpler states are confirmed with known data in the literature. The effects of various parameters such as nonlocality, porosity volume fractions, type of temperature rising, gradient index, opening angle and aspect ratio of curved FG porous nanobeam on the natural frequency are successfully discussed. It is concluded that these parameters play key roles on the dynamic behavior of porous FG curved nanobeam. Presented numerical results can serve as benchmarks for future analyses of curve FG nanobeam with porosity phases.

• Journal of Nutrition and Health
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• v.42 no.1
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• pp.48-58
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• 2009

This study was conducted to investigate effects of nutrition education and exercise intervention on health and diet quality of middle-aged women. The subjects were 209 women who wanted to involve in the health promotion program run by Jincheon-Gun Health Center. Nutrition education was given once a week and dance sports were done twice a week for 3 months. Nutrient intakes were assessed by 24-hour recall method and food records. Dietary habits and nutrition knowledge were investigated by self-administered questionnaires before and after the intervention program. Body and blood compositions were measured before and after the program. The nutrient adequacy ratio (NAR) was significantly increased in energy, protein, vitamin A, vitamin B2 and calcium, mean adequacy ration (MAR) was significantly increased (p < 0.05), and also the index of nutritional quality (INQ) was significantly increased in protein (p < 0.01). Percent (%) RIs of protein (p < 0.01) and calcium (p < 0.05) were significantly increased and body weight (p < 0.001), body fat (p < 0.01), soft lean mass (p < 0.01) and BMI (p < 0.001) decreased. Over the 3-month study, there was a significant trend toward higher HDL-C and albumin levels and lower LDL-C level (p < 0.001). The results showed that nutrition education and exercise intervention could improve the body health and the diet quality.

• Journal of Nutrition and Health
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• v.33 no.3
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• pp.304-313
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• 2000

This study was performed to assess diet quality in the postmenopausal women. The data of dietary intakes were obtained using food frequency questionnaires which were collected from 151 postmenopausal women in urban area. We evaluated nutrient intake and diet quality. Diet quality was assessed by NAR(nutrient adequacy ratio), FGIP(food group intake pattern), DDS(dietary diversity score), DVS(dietary variety score), FGS(food group score), DQI(diet quality index). Nutrient intakes of the subjects were close to Korean RDA. Nutrient composition of the diet(in percentage of total energy) was 64% carbohydrate, 15% protein, and 19% protein, and 19% total fat, that was close to 65 : 15 : 20. NAR of most nutrients, except vitamin A, E, were higher than 0.75 and MAR was 0.88. NAR and MAR of the subjects in theis study were higher than those of the subjects of rural area in other studies. The subjects who consumed the five food groups were 60.9%. The mean of DDS was 4.5. The subjects who consumed more than 61 dish items during a month were 61.5%. The mean of DVS was 62.4 and it was significantly higher in the elder age group. 67.6% of the subjects were below FGS of 12. The mean of FGS was 10.6 and few subjects consumed serving numbers of each food groups which were recommended for Koreans. 55.0% of the subjects were DQI scores of 0, 1, and 2. The mean of DQI was 2.3 and few subjects followed the five dietary guidelines for Korean.

• Journal of Nutrition and Health
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• v.37 no.2
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• pp.143-152
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• 2004

A dietary survey was conducted using 24-hour recall method in 80 male elementary school children, 83 high school students, 87 adults and 98 elderly people over 65 years of age to discuss food and nutrient intakes among different age groups. In observing food intake by age groups, the percentage of plant foods to total food intake was significantly higher in the elderly than other groups and that of animal foods was the highest in the children. The children consumed significantly higher amounts of milk and dairy products. Carbohydrate energy percent in the elderly people was 68.0%, significantly higher than other age groups. All age groups consumed Ca below Korean RDA and especially, 65.1% of the adolescents and 68.4% of the elderly consumed below 75% of RDA. Nutrient adequacy ratio (NAR) of most nutrients was lowest in the elderly. Mean adequacy ratio (MAR), an index of overall dietary quality, was 0.94 for the children, 0.84 for the adolescents, 0.84 for the adults, and 0.73 for the elderly. The above results suggest that food and nutrient intakes have been differently affected with advancing age, and overall dietary quality of the elderly people is lower than that of other age groups. (Korean J Nutrition 37(2): 143-152, 2004)

• Journal of Fisheries and Marine Sciences Education
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• v.21 no.2
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• pp.269-277
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• 2009

Ventilation equipment performs a central role to maintain comfort subway environment. So ventilation equipment of Busan subway line No.1 is required to improve thermal environment. In this study, conditions of thermal environment are presented to improve ventilation equipment at existing subway station platforms by measuring thermal environment of platforms operated ventilation equipment at 14 stations of Busan subway line No.1. AWS of data in comparison with the neighbouring platforms and thermal environment analysis. Thermal environment status of subway platform analysis results are as follows. 1)Daytime platform temperature was higher than outdoor temperature, but night time platform temperature was lower than outdoor temperature. 2)Train wind had effect on improving thermal comfort in platform. 3)When outdoor temperature is below $24^{\circ}C$, inlet air is able to lower than platform temperature. 4)Considering existing ventilation system, night purge systems is useful to improving platform thermal environment.

• Safety and Health at Work
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• v.11 no.3
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• pp.314-321
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• 2020

Background: Occupational accidents occur for a variety of reasons, such as unsafe behaviors of workers and insufficient safety equipment at the workplace, but there are also various economic and social factors that can impact working conditions and working environment. This study analyzed the relationship between changes in economic factors and the occurrence of occupational accidents in Korea. Methods: Multilinear regression analysis was used as the analysis model. The general to specific method was also used, which consecutively removes statistically insignificant variables from a general model that includes dependent variables and lagged variables of dependent variables. Results: The frequency of occupational accidents was found to have a statistically significant relationship to economic indicators. The monthly number of cases of occupational injury and disease and fatal occupational injuries were found to be closely related to manufacturing capacity utilization, differences in the production index in the services sector, and commencements of building construction. The increase in equipment investment indicators was found to reduce fatal occupational injuries. Conclusion: The results of this study may be used to develop occupational accident trends or leading indicators, which in turn can be used by organizations that manage and monitor occupational accidents toward taking administrative action designed to reduce occupational accidents. The results also imply that short-term and mid- to long-term economic and social changes that can impact workers, workplaces and working conditions, and workplace organizations must be taken into account if more effective government policies are to be established and implemented toward further prevention of occupational accidents.

• Tribology and Lubricants
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• v.19 no.4
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• pp.230-236
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• 2003

In applications such as MEMS and NEMS devices, the adhesion force and contact load may be of the same order of magnitude and the static friction coefficient can be very large. Such large coefficient may result in unacceptable and possibly catastrophic adhesion, stiction, friction and wear. To obtain the static friction coefficient of contacting real surfaces without the assumption of an empirical coefficient value, numerical simulations of the contact load, tangential force, and adhesion force are preformed. The surfaces in dry contact are statistically modeled by a collection of spherical asperities with Gaussian height distribution. The asperity micro-contact model utilized in calculation (the ZMC model), considers the transition from elastic deformation to fully plastic flow of the contacting asperity. The force approach of the modified DMT model using the Lennard-Jones attractive potential is applied to characterize the intermolecular forces. The effect of the surface topography on the static friction coefficient is investigated for cases rough, intermediate, smooth, and very smooth, respectively. Results of the static friction coefficient versus the external force are presented for a wide range of plasticity index and surface energy, respectively. Compared with those obtained by the GW and CEB models, the ZMC model is more complete in calculating the static friction coefficient of rough surfaces.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.4
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• pp.344-351
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• 2007

In this paper, we propose an approach to design multi-fuzzy controllers for the superheat and the low pressure that have an influence on energy efficiency and stabilization of air conditioning system with multi-evaporators. Air conditioning system with multi-evaporators is composed of compressor, condenser, several evaporators and several expansion valves. It is quite difficult to control the air conditioning system because the change of the refrigerant condition give an impact on the overall air conditioning system. In order to solve the drawback, we design multi-fuzzy controllers which control simultaneously both three expansion valve and one compressor for the superheat and the low pressure of air conditioning system. The proposed multi fuzzy controllers are given as a kinds of controller types such as a simplified fuzzy inference type. Here the scaling factors of each fuzzy controller are efficiently adjusted by Hierarchical Fair Competition-based Genetic Algorithms. The values of performance index of the simulation results of the A company type compare with simulation results of simplified inference type.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.15 no.1
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• pp.53-59
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• 2008

Purpose: The purpose of this study was to examine the effects of treadmill walking exercise on the BMD (Bone Mineral Density) and BMI (Body Mass Index) of middle-aged women in their forties. Method: A nonequivalent control group pretest-posttest design was used for this study. The experiment was conducted for 10 weeks from May 17 to July 25, 2004 with 29 middle-aged women in their forties, who were assigned to a walking exercise group (16) or a control group (13). The experimental group had not exercised regularly before participating in this program. The control group received no exercise treatment during the research period. The BMD and BMI were measured with peripheral dual energy x-ray absorptiometry and bioelectrical impidence analysis, respectively. $X^2-test$ and Mann-Whitney U test with the SPSS version 11.0 program were used to analyze the data. Result: Treadmill walking exercise was effective for middle-aged women in increasing BMD and decreasing BMI. Conclusion: The findings of this study indicate a need to develop walking exercise protocols for middle-aged women to help them achieve a healthy life.

• Structural Engineering and Mechanics
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• v.8 no.5
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• pp.513-529
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• 1999

A concept of hierarchical modeling, the newest modeling technology, has been introduced in early 1990's. This new technology has a great potential to advance the capabilities of current computational mechanics. A first step to implement this concept is to construct hierarchical models, a family of mathematical models sequentially connected by a key parameter of the problem under consideration and have different levels in modeling accuracy, and to investigate characteristics in their numerical simulation aspects. Among representative model problems to explore this concept are elastic structures such as beam-, arch-, plate- and shell-like structures because the mechanical behavior through the thickness can be approximated with sequential accuracy by varying the order of thickness polynomials in the displacement or stress fields. But, in the numerical, analysis of hierarchical models, two kinds of errors prevail, the modeling error and the numerical approximation error. To ensure numerical simulation quality, an accurate estimation of these two errors is definitely essential. Here, a local a posteriori error estimator for elastic structures with thin domain such as plate- and shell-like structures is derived using the element residuals and the flux balancing technique. This method guarantees upper bounds for the global error, and also provides accurate local error indicators for two types of errors, in the energy norm. Compared to the classical error estimators using the flux averaging technique, this shows considerably reliable and accurate effectivity indices. To illustrate the theoretical results and to verify the validity of the proposed error estimator, representative numerical examples are provided.