• 자원ㆍ환경경제연구
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• 제28권3호
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• pp.437-465
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• 2019

본 연구에서는 장기 전력 수요와 GDP 사이의 소득계수를 시간과 GDP의 값에 따라 변화하도록 모형화한 Chang et al.(2016)에 기반을 두어 장기 에너지 수요의 예측에 관련된 새로운 방법을 제안한다. 본 논문에서는 장기 에너지와 GDP 사이의 소득계수를 함수로 표현하고, 함수 주성분 분석(Functional Principal Component Analysis)을 통하여 함수계수(Functional Coefficient)를 예측하고 이를 장기 에너지 수요 예측에 적용한다. 또한 함수계수를 비모수적으로 추정할 때 너비띠 모수를 예측 실험 오차를 최소화하도록 설정하는 방식을 제안하였고 개별 국가의 함수계수 변화 패턴을 반영하여 개별 국가의 특수성을 반영하는 예측 방법도 제시한다. 실증분석에서는 전 세계 에너지 데이터를 이용하여 한국의 장기 에너지 수요 예측을 본 논문에서 제시한 방법으로 예측하고, 기존의 방법들 보다 안정적인 장기 에너지 수요 예측이 가능함을 보였다.

• 한국수자원학회논문집
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• 제37권12호
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• pp.1055-1063
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• 2004

공간적 위치 및 유량 값에 따라 각 계산점마다 조도계수의 값이 달리 주어질 수 있도록 하는 가변 조도변수 부정류 계산모형을 수립하였다. 유량과 조도계수의 관계식으로는 계단함수 또는 멱함수를 적용할 수 있도록 하였다. 수립된 모형을 충주댐부터 팔당댐까지의 남한강 구간에 적용하여 최적화에 의한 매개변수의 추정을 수행하였다. 가변 매개변수 모형의 보정 결과, 계단함수 도형 및 멱함수 모형 모두 유량이 커질수록 조도계수가 감소하는 경향이 일관되게 나타났다. 이러한 경향은 여주 지점 상류구간의 경우에 더욱 현저한 것으로 나타났다. 가변 조도계수 모형의 매개변수 추정에 따른 오차가 고정 조도계수 모형의 경우보다 작아짐을 알 수 있었다.

• Journal of Information Technology Applications and Management
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• 제28권1호
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• pp.95-110
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• 2021

This study aims to explore the Internet personal broadcasting quality factors that influence viewer satisfaction and dissatisfaction based on the motivation-hygiene theory. Specifically, the quality factors that affect viewer satisfaction of Internet personal broadcasting are derived from the perspectives of extrinsic (contents usefulness and media usability), intrinsic (emotional/cognitive/behavioral enjoyment and creator characteristics), and social motivation (visibility, subjective norm, image, sociality). The data of 200 respondents was used to analyze the relative impact of satisfaction and dissatisfaction with the Kano model, which assumes that viewer satisfaction at both functional and emotional levels varies over quality attributes. In the empirical analysis, the quality factors were classified into attractive, one-dimensional, must-be, and indifferent quality. In addition, it was found that the customer satisfaction coefficient was high in the order of uniqueness, differentiation, and visibility. On the other hand, as a result of applying the dissatisfaction coefficient, it was identified in the order of donation, content reliability, and creator responsiveness.

• 국제초고층학회논문집
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• 제5권2호
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• pp.95-103
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• 2016

One of the key problems in the design of high-rise commercial complex is how to guide reasonable pedestrian distribution in commercial space. In this study, pedestrian distribution in three high-rise commercial complexes in Shanghai and Hong Kong was studied using spatial configuration analysis software Space Syntax and quantification of physical elements in commercial spaces, such as functional attractiveness, entrances, escalators, level variations and passage width. Additionally, in an attempt to integrate functions with spatial integration and spatial depth, two combination variables, the spatial coefficient of function (IF) and spatial depth coefficient of function (F/D), were proposed. The results of the correlation analysis and multiple regression analyses reflected the following: (1) Regarding the influence on pedestrian distribution, there was a synergistic and complementary relationship between function and space; (2) The comprehensive flow distribution analytic model could successfully interpret flow distribution in high-rise commercial complexes and its R Square ranged up to about 70% in the three cases; (3) The spatial coefficient of function (IF) and spatial depth coefficient (F/D) could effectively integrate functions and spatial configuration, which could help close the gap between over-emphasis on function in commercial research and the lack of consideration of function in space-syntax analysis.

• Tribology and Lubricants
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• 제15권2호
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• pp.193-198
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• 1999

Applying design methodology, new type friction tester has been developed. Functional analysis has been executed and functional structure were constructed during the conceptual design. Optimal solution has been selected and a proto model has been manufactured according to the conceptual design. Using the tester developed in the laboratory, frictional characteristics of natural rubbers have been experimentally analyzed. Friction coefficient has been calculated from the measured normal force and friction force under various speeds, loads, and temperatures. The corelations between the various operating conditions and friction coefficients have been verified. Especially, drag friction due to the visco-elastic behavior of the rubber has been observed in this analysis.

• Elastomers and Composites
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• 제51권4호
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• pp.308-316
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• 2016

The rubber materials are widely used in automobile industry due to their capability of a large amount of elastic deformation under a force. Current trend of design process requires prediction of functional properties of parts at early stage. The behavior of rubber material can be modeled using strain energy density function. In this study, five different strain energy density functions - Neo-Hookean model, Reduced Polynomial $2^{nd}$ model, Ogden $3^{rd}$ model, Arruda Boyce model and Van der Waals model - were used to estimate the behavior of carbon black added natural rubber under uniaxial load. Two kinds of tests - uniaxial tension test and biaxial tension test - were performed and used to correlate the coefficients of the strain energy density function. Numerical simulations were carried out using finite element analysis and compared with experimental results. Simulation revealed that Ogden $3^{rd}$ model predicted the behavior of carbon added natural rubber under uniaxial load regardless of experimental data selection for coefficient correlation. However, Reduced Polynomial $2^{nd}$, Ogden $3^{rd}$, and Van der Waals with uniaxial tension test and biaxial tension test data selected for coefficient correlation showed close estimation of behavior of biaxial tension test. Reduced Polynomial $2^{nd}$ model predicted the behavior of biaxial tension test most closely.

• 근관절건강학회지
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• 제20권3호
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• pp.225-234
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• 2013

Purpose: This purpose of study was to investigate the relationships among functional state, self-efficacy, and life satisfaction in the elderly with decreased visual acuity. Methods: The subjects were 162 elderly people from the G university hospital. Functional state was measured by Late-Life Function and Disability Instrument (LLFDI) and Minimum Data Set-Home Care version 2.0 (MDS HC 2.0). Self-efficacy and Life satisfaction were measured by the tool of Rho & Lee (2011) and Yoon (2007). Data were analyzed using t-test, ANOVA, Pearson's Correlation Coefficient, and logistic regression. Results: The daily life function was significantly associated with self-efficacy and vision decrease. The regression model with these two variables explained 35.6% of the variance of daily life function. IADL was significantly associated with vision decrease, age, gender, and self-efficacy. The regression model with the three variables explained 52.9% of the variance of IADL. Life satisfaction is significantly associated with self-efficacy, daily life function, vision decrease and IADL. The last regression model with the four variables explained 51.8% of the variance of life satisfaction. Conclusion: The levels of functional state, self-efficacy and life satisfaction in the elderly with decreased visual acuity were low. Self-efficacy was an important factor that influences on the functional state and life satisfaction. Therefore, nursing interventions that can enhance the self-efficacy are required in order to increase the functional state and life satisfaction in the elderly with decreased visual acuity.

• Smart Structures and Systems
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• 제13권4호
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• pp.501-515
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• 2014

This paper presents a linear computational homogenization framework to evaluate the effective (or generalized) electromechanical coupling coefficient (EMCC) of adaptive structures with piezoelectric structural fiber (PSF) composite elements. The PSF consists of a silicon carbide (SiC) or carbon core fiber as reinforcement to a fragile piezo-ceramic shell. For the micro-scale analysis, a micromechanics model based on the variational asymptotic method for unit cell homogenization (VAMUCH) is used to evaluate the overall electromechanical properties of the PSF composites. At the macro-scale, a finite element (FE) analysis with the commercial FE code ABAQUS is performed to evaluate the effective EMCC for structures with the PSF composite patches. The EMCC is postprocessed from free-vibrations analysis under short-circuit (SC) and open-circuit (OC) electrodes of the patches. This linear two-scale computational framework may be useful for the optimal design of active structure multi-functional composites which can be used for multi-functional applications such as structural health monitoring, power harvest, vibration sensing and control, damping, and shape control through anisotropic actuation.

• 한국과학교육학회지
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• 제32권3호
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• pp.524-531
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• 2012

Categorization is an important human function used to process different stimuli. It is also one of the most important factors affecting measurement of a person's classification ability. Explicit categorization, the representative system by which categorization ability is measured, can verbally describe the categorization rule. The purpose of this study was to develop a prediction model for categorization ability as it relates to the classification process of living organisms using fMRI. Fifty-five participants were divided into two groups: a model generation group, comprised of twenty-seven subjects, and a model verification group, made up of twenty-eight subjects. During prediction model generation, functional connectivity was used to analyze temporal correlations between brain activation regions. A classification ability quotient (CQ) was calculated to identify the verbal categorization ability distribution of each subject. Additionally, the connectivity coefficient (CC) was calculated to quantify the functional connectivity for each subject. Hence, it was possible to generate a prediction model through regression analysis based on participants' CQ and CC values. The resultant categorization ability regression model predictor was statistically significant; however, researchers proceeded to verify its predictive ability power. In order to verify the predictive power of the developed regression model, researchers used the regression model and subjects' CC values to predict CQ values for twenty-eight subjects. Correlation between the predicted CQ values and the observed CQ values was confirmed. Results of this study suggested that explicit categorization ability differs at the brain network level of individuals. Also, the finding suggested that differences in functional connectivity between individuals reflect differences in categorization ability. Last, researchers have provided a new method for predicting an individual's categorization ability by measuring brain activation.

• Structural Engineering and Mechanics
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• 제80권5호
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• pp.523-538
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• 2021

The mechanical behaviour and stability of coal mining engineering underground is significantly affected by ground water. In this study, nuclear magnetic resonance imaging (NMRI) technique was employed to determine the water distribution characteristics in coal specimens during saturation process, based on which the functional rule for water distribution was proposed. Then, using discrete element method (DEM), an innovative numerical modelling method was developed to simulate water-weakening effect on coal behaviour considering moisture content and water distribution. Three water distribution numerical models, namely surface-wetting model, core-wetting model and uniform-wetting model, were established to explore the water distribution influences. The feasibility and validity of the surface-wetting model were further demonstrated by comparing the simulation results with laboratory results. The investigation reveals that coal mechanical properties are affected by both water saturation coefficient and water distribution condition. For all water distribution models, micro-cracks always initiate and nucleate in the water-rich area and thus lead to distinct macro fracture characteristics. With the increase of water saturation coefficient, the failure of coal tends to be less violent with less cracks and ejected fragments. In addition, the core-wetting specimen is more sensitive to water than specimens with other water distribution models.