• 한국환경과학회지
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• 제19권2호
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• pp.149-155
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• 2010

Rainfalls would increase the discharges or stages of tributary channels in natural watersheds, which in turn augment the magnitude of main stream stages. Rising of water surface elevation in main streams can affect and damage the human activities because of the possibilities of the breakdown or overflow of the embankment. Therefore it is necessary to establish the structural or non-structural alternatives for the sake of prevention or treatment of those disasters. Many mathematical models to analyze the flood flows in natural watercourses have been proposed as the non-structural alternatives so far. In this study one of the such models, FLDWAV developed by NWS(National weather Service), is applied to the downstream reach of Nakdong river. Model calibration is performed on various Manning's roughness coefficients at the gauging stations. The simulation results are compared well with hydrological estimations of flood discharges considering the effects of multipurpose dams upstream of control points.

• Structural Engineering and Mechanics
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• 제81권5호
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• pp.565-574
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• 2022

The infrastructures such as offshore, bridges, power plant, oil and gas piping and aircraft operate in a harsh environment during their service life. Structural integrity of engineering components used in these industries is paramount for the reliability and economics of operation. Two regression models based on the concept of Gaussian process regression (GPR) and Minimax probability machine regression (MPMR) were developed to predict stress intensity factor range (𝚫K). Both GPR and MPMR are in the frame work of probability distribution. Models were developed by using the fatigue crack growth data in MATLAB by appropriately modifying the tools. Fatigue crack growth experiments were carried out on Eccentrically-loaded Single Edge notch Tension (ESE(T)) specimens made of API 5L X65 Grade steel in inert and corrosive environments (2.0% and 3.5% NaCl). The experiments were carried out under constant amplitude cyclic loading with a stress ratio of 0.1 and 5.0 Hz frequency (inert environment), 0.5 Hz frequency (corrosive environment). Crack growth rate (da/dN) and stress intensity factor range (𝚫K) values were evaluated at incremental values of loading cycle and crack length. About 70 to 75% of the data has been used for training and the remaining for validation of the models. It is observed that the predicted SIF range is in good agreement with the corresponding experimental observations. Further, the performance of the models was assessed with several statistical parameters, namely, Root Mean Square Error (RMSE), Mean Absolute Error (MAE), Coefficient of Efficiency (E), Root Mean Square Error to Observation's Standard Deviation Ratio (RSR), Normalized Mean Bias Error (NMBE), Performance Index (ρ) and Variance Account Factor (VAF).

• 아동학회지
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• 제12권1호
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• pp.113-128
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• 1991

The purpose of this study was to analyze the environment of poverty children as reported by the children on a questionnaire. The conception of the environment was divided into the physical environment and the sociopsychological environment. The dimensions of the physical environment included household, cultural, and play conditions. The sociopsychological environment included structural (family values, family relationships, and the reinforcement system) and process variables(affect, care, and communication). For the purpose of this survey was administered to 122 children living in a poverty area and 102 children living in a middle-high income area. Statistics used for data analysis were frequency, distribution, percentile, mean and one-way ANOVA. Major findings showed that (1) The physical environment as reported by the poverty children was meager compared with that of children in the middle-high income area: the households were more overcrowded, and cultural conditions, play materials, and space was more limited. (2) The Structural conditions of the sociopsychological environment as perceived by poverty children were more material and physical than that of children in the middle-high income area: family values were oriented more toward materialism: family relationships were more negative and distant: and the reinforcement system was based more on material reward and physical punishment. (3) Process variables were perceived by poverty children as more laissez-faire and rigid; the parents neglected their children and communicated unilaterally more than the middle-high income parents. (4) Poverty children's perception of the causes of poverty and wealth were perceived as personal and social factors.

• 한국실내디자인학회논문집
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• 제25호
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• pp.42-48
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• 2000

The building remodeling is providing a lot of solutions - structural, aesthetic, environmental, and energy performance improvement - in improving buildings performance and environment. The remodelings influences on our society are resource conservation, environmental conservation, expansion of construction market, and creation of new employment. The three principal remodeler groups involved in this building remodeling are general construction contractors, interior architecture contractors, and ESCO (Energy Service Company). Having a representative character, this study classifies remodeling methods into five types: structural remodeling, spatial remodeling, exterior remodeling, environment-friendly remodeling, and ecological remodeling.

• 지역사회간호학회지
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• 제18권4호
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• pp.624-633
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• 2007

Purpose: The purpose of this study was to develop and test a structural model on work-related musculoskeletal disorders of women workers. Method: Data were collected from 237 women workers from industries such as electronics, food production and garment production, and analyzed by LISREL 8.54. Result: The fitness indices of the model are GFI=.87, NNFI=.91, PNFI= .74. Eight out of the ten paths were proved to be statistically significant: work environment$\rightarrow$social support, work environment$\rightarrow$health behavior, work environment$\rightarrow$-WMSDs, domestic work$\rightarrow$health behavior, social support$\rightarrow$health behavior, social support$\rightarrow$job satisfaction, health behavior$\rightarrow$job satisfaction, and job satisfaction$\rightarrow$WMSDs. Work environment. social support, health behavior and job satisfaction significantly influenced WRMDs. WRMDs were accounted for 35% by the predictor variables. Conclusion: In conclusion, this study identifies that work environment, social support, health behavior and job satisfaction are important factors affecting WMSDs. Therefore, in order to prevent WRMDs, it is most important to improve both physical work environment for female workers such as appropriate work station and tools fit for them and psychological environment such as less job demand and more decision latitude(worker control).

• 대한가정학회지
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• 제44권11호
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• pp.117-131
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• 2006

The purpose of this study was to verify a Structural Equation Model that constructed the causations among the structural leisure constraints, interpersonal leisure constraints, intrapersonal leisure constraints, leisure motivation, leisure activity participation, leisure satisfaction and the quality of life from the ecological perspective. The respondents were 301 elderly people residing in 4 free institutionalized elderly homes in Seoul. The data were analyzed by confirmatory factor analysis and covariance structure analysis using USREL 8.0 ver. The major results are summarized as follows: 1) Statistically, a goodness of fit is good of structural equation model presented in the study. 2) The structural leisure constraints and the interpersonal leisure constraints are some types of leisure environment of the aged in public homes from the ecological perspective. Such constraints would inevitably lead to a direct effect on individual leisure life and leisure motivation. 3) The important valuable factor which affected the leisure satisfaction and the quality of life in the elderly was the leisure motivation.

• Smart Structures and Systems
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• 제16권4호
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• pp.607-621
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• 2015

Wireless sensor technology has been opened up numerous opportunities to advanced health and maintenance monitoring of civil infrastructure. Compare to the traditional tactics, it offers a better way of providing relevant information regarding the condition of building structure health at a lower price. Numerous domestic buildings, especially longer-span buildings have a low frequency response and challenging to measure using deployed numbers of sensors. The way the sensor nodes are connected plays an important role in providing the signals with required strengths. Out of many topologies, the dense and sparse topologies wireless sensor network were extensively used in sensor network applications for collecting health information. However, it is still unclear which topology is better for obtaining health information in terms of greatest components, node's size and degree. Theoretical and computational issues arising in the selection of the optimum topology sensor network for estimating coverage area with sensor placement in building structural monitoring are addressed. This work is an attempt to fill this gap in high-rise building structural health monitoring application. The result shows that, the sparse topology sensor network provides better performance compared with the dense topology network and would be a good choice for monitoring high-rise building structural health damage.

• Structural Engineering and Mechanics
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• 제67권6호
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• pp.565-578
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• 2018

This research article reported the nonlinear finite solutions of the nonlinear flexural strength and stress behaviour of nano sandwich graded structural shell panel under the combined thermomechanical loading. The nanotube sandwich structural model is derived mathematically using the higher-order displacement polynomial including the full geometrical nonlinear strain-displacement equations via Green-Lagrange relations. The face sheets of the sandwich panel are assumed to be carbon nanotube-reinforced polymer composite with temperature dependent material properties. Additionally, the numerical model included different types of nanotube distribution patterns for the sandwich face sheets for the sake of variable strength. The required equilibrium equation of the graded carbon nanotube sandwich structural panel is derived by minimizing the total potential energy expression. The energy expression is further solved to obtain the deflection values (linear and nonlinear) via the direct iterative method in conjunction with finite element steps. A computer code is prepared (MATLAB environment) based on the current higher-order nonlinear model for the numerical analysis purpose. The stability of the numerical solution and the validity are verified by comparing the published deflection and stress values. Finally, the nonlinear model is utilized to explore the deflection and the stresses of the nanotube-reinforced (volume fraction and distribution patterns of carbon nanotube) sandwich structure (different core to face thickness ratios) for the variable type of structural parameter (thickness ratio, aspect ratio, geometrical configurations, constraints at the edges and curvature ratio) and unlike temperature loading.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2023년도 가을학술발표대회논문집
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• pp.143-144
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• 2023

The compressive strength of concrete varies depending on various factors. Among them, based on the curing temperature, the KCS 14 20 10 Standard Specification for General Concrete calculates the nominal strength by applying the temperature correction value (Tn) based on the compressive strength of the standard cured concrete at 20±2℃ when designing the formulation strength. However, Tn is a correction value that considers only the temperature, and the correction of strength difference due to heat of hydration is not applied. Therefore, in this study, one-component and two-component concrete are mixed in the summer, structural concrete are manufactured, standard concrete specimen are manufactured, and coring is performed on the central and boundary parts of the structural concrete to calculate the correction value applied to the nominal strength by comparing the compressive strength of standard cured concrete on the 28th day of curing and the compressive strength of structural concrete on the 91st day of curing.

• 한국환경생태학회:학술대회논문집
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• 한국환경생태학회 2003년도 추계학술논문발표회 논문집
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• pp.214-217
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• 2003