• The Korean Journal of Applied Statistics
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• v.31 no.6
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• pp.785-799
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• 2018

With the development of renewable energy sector, the importance of solar energy is continuously increasing. Solar radiation forecasting is essential to accurately solar power generation forecasting. In this paper, we used time series models (ARIMA, ARIMAX, seasonal ARIMA, seasonal ARIMAX, ARIMA GARCH, ARIMAX-GARCH, seasonal ARIMA-GARCH, seasonal ARIMAX-GARCH). We compared the performance of the models using mean absolute error and root mean square error. According to the performance of the models without exogenous variables, the Seasonal ARIMA-GARCH model showed better performance model considering the problem of heteroscedasticity. However, when the exogenous variables were considered, the ARIMAX model showed the best forecasting accuracy.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.20 no.1
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• pp.10-21
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• 2021

This study analyzed how external variables, such as the supply policy of shared bicycles and the spread of infectious diseases, affect the demand for shared bicycle use in the COVID-19 era. In addition, this paper presents a methodology for more accurate predictions. The Seasonal Auto-Regulatory Integrated Moving Average with Exogenous stressors methodology was applied to capture the effects of exogenous variables on existing time series models. The exogenous variables that affected the future demand for shared bicycles, such as COVID-19 and the supply of public bicycles, were statistically significant. As a result, from the supply volume and COVID-19 outbreak according to the scenario, it was estimated that approximately 46,000 shared bicycles would be supplied by 2022, and the COVID-19 cases would continue to be at the current level. In addition, approximately 32 million and 45 million units per year will be needed in 2021 and 2024, respectively.

• The Journal of the Korea Contents Association
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• v.22 no.1
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• pp.214-223
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• 2022

The purpose of this study is to present a new industrial land demand prediction method that can consider external economic factors. The analysis model used ARIMA-X, which can consider exogenous variables. Exogenous variables are composed of macroeconomic variable, Business Survey Index, and Composite Economic Index variables to reflect the economic and industrial structure. And, among the exogenous variables, only variables that precede the supply of industrial land are used for prediction. Variables with precedence in the supply of industrial land were found to be import, private and government consumption expenditure, total capital formation, economic sentiment index, producer's shipment index, machinery for domestic demand and composite leading index. As a result of estimating the ARIMA-X model using these variables, the ARIMA-X(1,1,0) model including only the import was found to be statistically significant. The industrial land demand forecast predicted the industrial land from 2021 to 2030 by reflecting the scenario of change in import. As a result, the future demand for industrial land was predicted to increase by 1.91% annually to 1,030.79 km². As a result of comparing these results with the existing exponential smoothing method, the results of this study were found to be more suitable than the existing models. It is expected to b available as a new industrial land forecasting model.

• Journal of the Korean Institute of Landscape Architecture
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• v.20 no.1
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• pp.29-38
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• 1992

The primary objective of this study is to investigate factors and variables which have significant effects on user satisfaction with recreational facilities in Children's Grand Park in Pusan City, theregby to establish the developmental way of urban park and open space. To test the causal models of this research, the data were gathered by self-administered questionnaires from 1085 households in Pusan City which were selected by the multi-stage probability sampling method. The analysis of the data primarily consists of two phase : The fist analysis dealt exploratory factor analysis which identified major factors involved in satisfaction with recreational facilities in Children's Grand Park and the second analysis tested the fit of the causal models of this research by employing LISREL methodology. The factor analysis identified that five factors are involved in satisfaction with recreational facilities. The five factors of satisfaction with recreational facilities are convenience and maintanance facilities, learnded recreational facilities, spaces for repose and relaxation, spaces for active recreation failities, and facilities for health and physical facilities. The second phase analysis tested the fit of the causal models for satisfaction with recreational facilities to the data and identified statistically significant causal linkage among overall satisfaction with Children's Grand Park, other endogenous factors and exogenous variables. Overall fits of both causal models were very good. Among endogenous factors, facilities for repose and relaxation, facilities for convenience and maintenance, learnded recreational facilities were identified as having significant effects on overall satisfaction. Exogenous variables which have significant effects on endogenous variables were also identified. These significant relationships indicate important factors and variables that should be considered in planning and development of urban park and open space. On the basis of these significant causal relationships, way for delovepment of urban park and open space were suggested.

• The Journal of Industrial Distribution & Business
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• v.9 no.4
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• pp.63-72
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• 2018

Purpose - The purpose of this paper is to investigate the effects of online game properties, social interaction, and player satisfaction on intention to online games in Chinese gamers. Research design, data, and methodology - This study is an empirical analysis assuming that properties of online games, social interaction and satisfaction will induce Chinese gamers' intention to play online games. We set the relationship between the six variables as follows. First, the properties of online games, exogenous variables, were identified by three factors: entertainment, security, participation and challenge. Second, we had input social interaction among gamers as another exogenous variables. Third, the gamer's satisfaction of online games was added to the research model as a mediating variable between exogenous variables and endogenous variables. Finally, gamer's intention to play influenced by satisfaction and social interaction was used as final endogenous variable. The data used for the empirical analysis were collected through questionnaires for Chinese under age 35 who enjoy the online games. The data used in the research were finally extracted from 195 questionnaires. The collected data were tested through the analysis of the measurement model (Step 1) and the analysis of the structural model (Step 2). The covariance structure equation model (SEM) was used for the analysis. The measurement model and structural model were evaluated by the maximum likelihood method. Results - The results of the empirical analysis are as follows. The satisfaction of online games were entertainment and security had a significant effect to satisfaction; but participation and challenge and social interaction had no significant effect on satisfaction. The social interaction among gamers and the satisfaction with online games have a significant influence on the intention to play online games. As a result, the attributes of the game were affecting the intention to play the game after satisfaction. Social interaction influenced the intention to play online games rather than satisfaction itself. Conclusions - This study provide some practical implications for the new companies who want to enter the online game industry and seek to competitiveness in China, and provide theoretical implications on the role of interaction among gamers in the study of online games.

• Journal of the Korean Home Economics Association
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• v.32 no.3
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• pp.171-184
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• 1994

This study examined the characteristics of the relationship of environmental variables that is HOME socio-demographic variables and children's verbal ability at age five. Especially this study investigated causal relationships among the variables which are supposed to affect children's verbal ability. The subjects of this study were 60 children at age five and their mothers. Instruments included inventory of home stimulation(HOME) inventory of socio-demographic variables inventory of the children's verbal ability and intelligence test. The results obtained from study were as follows: 1. For the most part environmental variables had a significant positive correlation with children's verbal ability 2. The variables that significantly predicted boy's verbal ability were aspects of physical environment breadth of experienc. And the variables that significantly predicted girls' verbal ability were developmental stimulation economic status of the home. 3. The results of the analysis of the causal model showed that the kind of variables that affected boy's verbal ability directly were indirect stimulation direct stimulation. And the kind of variables that affected girls' verbal ability directly were direct stimulation econmic status of the home inditect stimulation. 4. Another causal model of the environmental variables affecting children's verbal ability were formulated by exogenous variables(socio-demographic variables) and by endogenous variables (HOME, children's intelligence). The results of the analysis of the causal model showed that only HOME variables significantly affected boy's and girls' verbal ability directly.

• Journal of the Korean Society of Clothing and Textiles
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• v.44 no.6
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• pp.1053-1069
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• 2020

This study examined the sales pattern relationship with respect to product attributes to propose sales forecasting for fashion products. We analyzed 537 SKU sales data of T-shirts in the domestic sports brand using SAS program. The sales pattern of fashion products fluctuated and were influenced by exogenous factors; therefore, we removed the influence of exogenous factors found to be price discounts and holiday effects as a result of regression analysis. In addition, it was difficult to predict sales using the sales patterns of the same product since fashion products were released as new products every year. Therefore, the forecasting model was proposed using sales patterns of related product attributes when attributes were considered descriptive variables. We classified sales patterns using K-means clustering in order to explain the relationship between sales patterns and product attributes along with creating a decision tree classifier using attributes as input and sales patterns as output. As a result, the sales patterns of T-shirts were clustered into six types that featured the characteristic shape of peak and slope. It was also associated with the combination of product attributes and their values in regards to the proposed sales pattern prediction model.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.437-437
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• 2022

The prediction of dam inflow rate is crucial for the management of the largest multi-purpose dam in South Korea, the Soyang Dam. The main issue associated with the management of water resources is the stochastic nature of the reservoir inflow leading to an increase in uncertainty associated with the inflow prediction. The Autoregressive (AR) model is commonly used to provide the simulation and forecast of hydrometeorological data. However, because its estimation is based solely on the time-series data, it has the disadvantage of being unable to account for external variables such as climate information. This study proposes the use of the Autoregressive Exogenous Stochastic Volatility (ARXSV) model within a Bayesian modeling framework for increased predictability of the monthly dam inflow by addressing the exogenous and stochastic factors. This study analyzes 45 years of hydrological input data of the Soyang Dam from the year 1974 to 2019. The result of this study will be beneficial to strengthen the potential use of data-driven models for accurate inflow predictions and better reservoir management.

• Journal of Families and Better Life
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• v.14 no.1
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• pp.35-46
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• 1996

This study was designed to investigate causal relationships among related variables that determined psychological distress of aged mothers. In this study questionaires were used to measure and subjects were 244 mothers aged over 60 and lived in K city. 221 answers were analyzed by SAS and covarince structure analysis. The results were as follows: it was found that pocketmoney and health had direct effects on objective solidarity education level pocketmoney and activity on subjective solidarity marital status and health on psychological distress between exogenous variables and endogenous variables. Among endogenous variables objective solidarity had direct effects on subjective solidarity and self-esteem subjective solidarity on self-esteem and self-esteem on psychological distress respectively. Subjective solidarity was found to be most effectable variable on psychological distress.

• Fashion & Textile Research Journal
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• v.22 no.5
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• pp.570-583
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• 2020

The fashion industry is accountable for labor and environment-related issues. With such issues raised, consumers' social responsibility for environmental and labor issues has become an important factor that shapes the perception of companies. This study investigates the relationship between consumer values, concerns regarding social issues, and willingness to pay a premium for ethical fashion products. This study included two exogenous variables of altruistic value and egocentric value. In the conceptual model, consumers' social responsibility was conceptualized as two constructs of environmental consciousness and labor-issue consciousness. It was then analyzed as mediating variables. Willingness to pay a premium for ethical fashion products was the endogenous variable. Data was collected and analyzed with PLS-SEM from 600 consumers. The assessment of discriminant validity and construct validity using CFA were conducted before analyzing the model. Structural equation modeling results revealed that altruistic value directly influenced environmental consciousness and labor-issue consciousness. However, egocentric value was directly and significantly influenced only by labor-issue consciousness. Both environmental and labor issue consciousness directly influenced customers' willingness to pay a premium, but did not significantly change their willingness to pay a premium. Two-stage serial mediation analysis results indicated that the constructs did not have a significant mediation effect on the exogenous variables (altruistic value and egocentric value) and the endogenous variable (willingness to pay a premium) for ethical fashion products. This study found the influence of consumer's personal values on their willingness to pay a higher price for ethical fashion products.