• 대한가정학회지
• /
• 제43권4호
• /
• pp.203-223
• /
• 2005

This study investigated the leisure constraints and leisure life satisfaction of the institutional elderly. The respondents were 302 elderly people residing in 5 free institutionalized elderly homes in Seoul. The data were analyzed by frequency analysis, factor analysis, One-way ANOVA, Duncan's post hoc test and regression analysis using SPSS WIN 12.0 program. Exploratory factor analysis revealed that the 10 items in the proposed scale could be grouped into four factors of constraint on leisure:'physical constraint','psychological constraint','interpersonal constraint', and 'structural constraint 'There were differences in leisure constraints according to sex, age, education degree, interaction with facility colleagues, and interaction with facility staff. There were differences in leisure life satisfaction according to sex, age, having religion or not, interaction with facility colleagues, interaction with facility staff and leisure constraints. Regression analysis results indicated that the main effective factors of leisure life satisfaction were leisure constraints.

• 한국수자원학회:학술대회논문집
• /
• 한국수자원학회 1992년도 수공학연구발표회논문집
• /
• pp.133-141
• /
• 1992

A three water-intake structure designed to built along the right bank of the Missouri River near Chesterfield, Missouri was model-tested at an undistorted scale of 1:5. Although the discharge capacity of each of six pumps to be installed is only 21,000 gpm, the model indicated strong flow circuation and unstable free-surface conditions as flow entered the two-pump bay through a narrow sluice opening at an angle. Strong free-surface vartices were also observed in the model. The sump modifications developed in the study included an array of baffle bars, a perforated plate, floor splitters, and floor-corner fillets. The solutions developed in this study could be applied to other pump sumps with multiple pump units.

• Smart Structures and Systems
• /
• 제25권4호
• /
• pp.501-514
• /
• 2020

This article presents a comprehensive model to investigate a free vibration and resonance frequencies of nanostructure perforated beam element as nano-resonator. Nano-scale size dependency of regular square perforated beam is considered by using nonlocal differential form of Eringen constitutive equation. Equivalent mass, inertia, bending and shear rigidities of perforated beam structure are developed. Kinematic displacement assumptions of both Timoshenko and Euler-Bernoulli are assumed to consider thick and thin beams, respectively. So, this model considers the effect of shear on natural frequencies of perforated nanobeams. Equations of motion for local and nonlocal elastic beam are derived. After that, analytical solutions of frequency equations are deduced as function of nonlocal and perforation parameters. The proposed model is validated and verified with previous works. Parametric studies are performed to illustrate the influence of a long-range atomic interaction, hole perforation size, number of rows of holes and boundary conditions on fundamental frequencies of perforated nanobeams. The proposed model is supportive in designing and production of nanobeam resonator used in nanoelectromechanical systems NEMS.

• 한국공간구조학회논문집
• /
• 제1권2호
• /
• pp.101-110
• /
• 2001

A large floating structure is attracting great attention in recent years from the view of ocean space utilization. Its huge scale in the horizontal directions compared with the wavelength and relatively shallow depth make this type of floating structure flexible and its wave-induced motion be characterized by the elastic deformation. In this paper, a boundary integral equation method is proposed to predict the wave-induced dynamic response mat-like floating offshore structure. The structure is modeled as an elastic plate and its elastic deformation is expressed as a superposition of free-vibration modes in air. This makes it straightforward to expand the well-established boundary integral technique for rigid floating bodies to include the hydroelastic effects. In order to validate the theoretical analysis, we compare with the experimental result of reduced model test. Satisfactory agreement is found between theory and experiment.

• 한국산업융합학회 논문집
• /
• 제4권4호
• /
• pp.433-439
• /
• 2001

A large floating structure is attracting great attention in recent years from the view of ocean space utilization. Its huge scale in the horizontal directions compared with the wavelength and relatively shallow depth make this type of floating structure flexible and its wave-induced motion be characterized by the elastic deformation. In this paper, a boundary integral equation method is proposed to predict the wave-induced dynamic response mat-like floating offshore structure. The structure is modeled as an clastic plate and its elastic deformation is expressed as a superposition of free-vibration modes in air. This makes it straightforward to expand the well-established boundary integral technique for rigid floating bodies to include the hydroelastic effects. In order to validate the theoretical analysis, we compare with the experimental result of previous model test. Satisfactory agreement is found between theory and experiment.

• 상하수도학회지
• /
• 제20권4호
• /
• pp.637-643
• /
• 2006

The bench-scale chlorine exposure study was performed to investigate the effect of pretreatment by free chlorine and monochloramine ($NH_2Cl$) on the performance of RO membranes made of polyamide (PA). Feed monochloramination at 2mg/L did not cause significant productivity loss compared to free chlorine. However, metal coagulants reacted with monochloramine, the PA membrane suffered from a gradual loss of membrane integrity by chlorine oxidation, which was characterized as a decrease in salt rejection. Especially, RO membranes exposed to alum coagulants with monochloramine revealed the salt rejection lower than those exposed to iron coagulants. XPS membrane surface analysis demonstrated that the chlorine uptake on the membrane surface increased and carbon peaks were shifted significantly when exposed to alum coagulants with monochloramine.

• Structural Engineering and Mechanics
• /
• 제65권3호
• /
• pp.335-342
• /
• 2018

The transverse free vibration of chiral double-walled carbon nanotube (DWCNTs) embedded in elastic medium is modeled by the non-local elasticity theory and Euler Bernoulli beam model. The governing equations are derived and the solutions of frequency are obtained. According to this study, the vibrational mode number, the small-scale coefficient, the Winkler parameter and chirality of double-walled carbon nanotube on the frequency ratio (xN) of the (DWCNTs) are studied and discussed. The new features of the vibration behavior of (DWCNTs) embedded in an elastic medium and the present solutions can be used for the static and dynamic analyses of double-walled carbon nanotubes.

• 통상정보연구
• /
• 제10권4호
• /
• pp.353-372
• /
• 2008

The economic development system of Korea is based on export-oriented strategy and the free trade agreement. So Korea is trying to conclude the free trade agreement with China, Japan, and EU. The reason is that Korea will have more chances to develop there economy scale and trade surplus, but it will give the worst economic situation. The research showed that the effects of FTA on Korea's GDP will be much greater than China's and Korea's trade surplus with China will expand in the manufacturing sector, but agricultural and marine products are layed in opposite situation. Especially comparing with other Provincial, Gwangju Jeonnam has a relative importance portion of agricultural and marine products. So, Gwangju Jeonnam have to prepare the effects of agricultural and marine products under the Korea China FTA.

• 품질경영학회지
• /
• 제43권3호
• /
• pp.239-252
• /
• 2015

Purpose: Lead has been widely used in radiation shielding for its low price and high workability. Recently in several europe countries, use of lead was banned for environmental issues. Also lead can cause health problems like alergies. Alternative materials for lead are highly required. The purpose of this study was to propose lead free radiation shielding material. Methods: Research of radiation shielding in Korea is not easy for certain limits such as radiation materials, experimental facilities and places. The collected data through the research were simulated using MCNPX. The simulation tools used for this study were utilized Monte Carlo method. Results: we suggest new design of lead free radiation shielding material using MCNPX code comparing shielding performance of new composite materials to lead. Conclusion: This newly introduced nano-scale composite of metal and polymer makes new chance for highly lightened radiation protective garments with endurable shielding performance.

• Steel and Composite Structures
• /
• 제34권4호
• /
• pp.599-613
• /
• 2020

In this article, free vibration attributes of double-walled carbon nanotubes based on nonlocal elastic shell model have been investigated. For this purpose, a nonlocal Flügge shell model is established to observe the small scale effect. The wave propagation is employed to frame the governing equations as eigenvalue system. The influence of nonlocal parameter subjected to different end supports has been overtly examined. A suitable choice of material properties and nonlocal parameter been focused to analyze the vibration characteristics. The new set of inner and outer tubes radii investigated in detail against aspect ratio and length. The dominance of boundary conditions via nonlocal parameter is shown graphically. The results generated furnish the evidence regarding applicability of nonlocal shell model and also verified by earlier published literature.