• Korea Trade Review
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• v.46 no.5
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• pp.213-230
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• 2021

China's e-waste enterprises can decompose 150 million sets of e-waste every year, but in fact, only about 50% of the e-waste goes into formal recycling due to the informal recycling of individual small businesses. The purpose of this paper is to put forward the method for users to improve the reuse times through regular e-waste recycling enterprises. This paper constructs the evaluation factors of reuse logistics service through prior research. Exogenous variables are mainly composed of the management system, economics, resources, policies, social perspectives, and service quality. In addition, the authors choose intention to reuse as an endogenous variable. A total of 335 questionnaires were collected to conduct the research with the structural equation modeling. The results reject the hypothesis that economics, resources, and social perspectives have a positive impact on reuse. On the contrary, management systems, policies, and service quality have a positive impact on reuse. Implications were suggested in the last part of the research.

• The Korean Journal of Applied Statistics
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• v.37 no.3
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• pp.297-309
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• 2024

This paper evaluates the performance of the neural network autoregressive model combined with an exponential smoothing model, called the NNARX+ETS model. The combined model utilizes the components of ETS as exogenous variables for NNARX, to forecast time series data using artificial neural networks. The main idea is to enhance the performance of NNAR using only lags of the original time series data, by combining traditional time series analysis methods with the neural networks through NNARX. We employ two real data for performance evaluation and compare the NNARX+ETS with NNAR and traditional time series analysis methods such as ETS and ARIMA (autoregressive integrated moving average) models.

• Journal of Intelligence and Information Systems
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• v.26 no.3
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• pp.1-36
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• 2020

This study is to reveal the acceptance factors of the Market Sentiment Index (MSI) created by reflecting the investor sentiment extracted by processing unstructured big data. The research model was established by exploring exogenous variables based on the rational behavior theory and applying the Technology Acceptance Model (TAM). The acceptance of MSI provided to investors in the stock market was found to be influenced by the exogenous variables presented in this study. The results of causal analysis are as follows. First, self-efficacy, investment opportunities, Innovativeness, and perceived cost significantly affect perceived ease of use. Second, Diversity of services and perceived benefits have a statistically significant impact on perceived usefulness. Third, Perceived ease of use and perceived usefulness have a statistically significant effect on attitude to use. Fourth, Attitude to use statistically significantly influences the intention to use, and the investment opportunities as an independent variable affects the intention to use. Fifth, the intention to use statistically significantly affects the final dependent variable, the intention to use continuously. The mediating effect between the independent and dependent variables of the research model is as follows. First, The indirect effect on the causal route from diversity of services to continuous use intention was 0.1491, which was statistically significant at the significance level of 1%. Second, The indirect effect on the causal route from perceived benefit to continuous use intention was 0.1281, which was statistically significant at the significance level of 1%. The results of the multi-group analysis are as follows. First, for groups with and without stock investment experience, multi-group analysis was not possible because the measurement uniformity between the two groups was not secured. Second, the analysis result of the difference in the effect of independent variables of male and female groups on the intention to use continuously, where measurement uniformity was secured between the two groups, In the causal route from usage attitude to usage intention, women are higher than men. And in the causal route from use intention to continuous use intention, males were very high and showed statistically significant difference at significance level 5%.

• Journal of muscle and joint health
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• v.8 no.1
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• pp.5-26
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• 2001

Many studies have reported that regular aquatic exercise can lead to improvement of health for patients suffering from arthritis. In spite of these benefits, the adherence rate has shown as few as 26% of patients with arthritis who had completed the aquatic exercise education program. Moreover, when patients with arthritis begin an aquatic exercise, 47% withdraw within the first 6 month. No study has been found that constructs model to explain aquatic exercise adherence of patients with arthritis. The purpose of this study were to identify the factors influencing exercise adherence and to construct and test a structural model to explain aquatic exercise adherence of patients with arthritis. Hypothesized model was constructed on the basis of Bandura's social cognitive theory and literature review. Exogenous latent variables included in this model are group cohesion and barrier, endogenous latent variables are self-efficacy, outcome expectancy and self-evaluation. Empirical data used was collected through individual interviews with the structural questionnaire on 249 patients with arthritis who had completed the 6-week aquatic exercise education program of Korean Rheumatology Health Professionals Academy. The interviews were performed from September 6, 1999 through October 8, 1999. A model tested by the covariance structural analysis with LISREL 8.12a program and by descriptive statistics and correlation with SAS 6.12 program. The results are summarized as follows: First, hypothesized model showed a good fit to the empirical data. In the modified model added one new path showed a much better fit. Second, group cohesion had a direct, indirect positive effects, self-efficacy and self evaluation had a direct positive effects on exercise adherence. Barrier had a direct, indirect negative effects on exercise adherence. Outcome expectancy had a direct negative effect, indirect positive effects through self-evaluation on exercise adherence, but total effects was not significant. Total effect size of the variables were group cohesion, self-efficacy, barrier and self evaluation in order. All variables accounted for 54% of the total variance of exercise adherence in the model. In conclusion, this model confirmed to be proper in explaining of aquatic exercise adherence. Group cohesion, self-efficacy, outcome expectancy, self-evaluation, barrier contributed to the aquatic exercise adherence of patients with arthritis. The results of this study suggested that improvement of group cohesion, self-efficacy and self-evaluation, motivation of outcome expectancy through self-evaluation, and reduction of the barrier should be included in the strategy of nursing intervention for the aquatic exercise adherence of patients with arthritis.

• Child Health Nursing Research
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• v.7 no.3
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• pp.280-297
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• 2001

The purpose of the study was to develop and test the model for the quality of life in mothers of children with nephrotic syndrome. A hypothetical model was constructed on the basis of previous studies and a review of literature. The conceptual framework was built around ten constructs. Exogenous variables included in this model were mother's health, father's health, marital intimacy, mother's attitude on children, economic state, side effect of steroid, severity of illness and social support. Endogenous variables were mother's burden and quality of life. Empirical data for testing the hypothetical model were collected by using a self-report questionnaire from 152 mothers of children with nephrotic syndrom at the outpatient clinics and in the hospital. The data was collected from May, 1999 to August, 1999.Reliability of the seven instruments was tested with Cronbach's alpha which ranged from 0.71 - 0.92.For the data analysis, SPSS 8.0 WIN program and LISREL 8.20 WIN program were used for descriptive statistics and covariance structural analysis. The results of covariance structural analysis were as follow :1. The hypothetical model showed a good fit with the empirical data. [x2 = .56, df = 3, p = .90(p>.05 ), GFI = .99, AGFI = .99, RMSR = .005.] 2. For the parsimony of model, a modified model was constructed by deleting 1 variable and excluding 2 paths according to the criteria of statistical significance and meaning.3. The modified model also showed a good fit with the data[x2 = 2.83, df = 7, p = .90( p>.05 ), GFI = 1.00, AGFI = .97, RMSR = .011].The result of the testing of the hypothesis were as follows : 1. Mother's health(γ21 = .26, t = 4.16), father's health(γ22 = .19, t = 2.92), marital intimacy(γ23 = .26, t = 4.13) and social support(γ28 = .12, t = 2.03) had a significant direct effect on the quality of life.2. Mother's burden(β21 = -.20, t = -3.10) had a significant negative direct effect on the quality of life.3. Mother's attitude on children(γ14 = -.34, t = .-4.57), mother's health(γ11 = -.22, t = -2.96) and side effect of steroid (γ16 = -.23, t = .-2.69) had a significant direct negative effect on the burden. The result of this study showed that mother's health, marital intimacy, mother's burden, father's health, and social support had a significant direct effect on the quality of life. Mother's attitude on children, mother's health, and side effect of steroid had a significant direct effect on mother's burden. These six variables, mother's health, marital intimacy, father's health, social support, mother's attitude on children and side effect of steroid were identified as relatively important variables. The results of this study suggest, it needed to determine the nursing intervention will alleviate mother's burden and promote a greater quality of life in mothers of children with nephrotic syndrom.

• Journal of the Korean Applied Science and Technology
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• v.38 no.6
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• pp.1405-1422
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• 2021

This study aimed to construct and test a hypothetical model to explain health-promoting behaviors among high school students in Korea. Data were collected from a self-administered questionnaire of 395 first-year to third-year students at a high school in Gyeonggi-do area. The exogenous variables of this study were family function, friend support, school life environment, and social capital of the local community, and endogenous variables were self-efficacy, self-regulation, and health-promoting behaviors. Data were analyzed by SPSS 21.0 and AMOS 22.0. The final model with 13 of the 9 analyzed paths showed a good fit to the empirical data: χ²/df=1.96, GFI=.90, AGFI=.88, CFI=.94, TLI=.93, RMSEA=.05, SRMR=.06. The variables included in these paths were family function (β=.57), self-efficacy (β=.29), self-regulation(β=.14), the social capital of local community (β=.14), and friend support (β=.13). The variables included in the nine significant paths explained 86% of variance in the explain model. Thus, it is necessary to build up a social support system for dysfunctional families and health-promoting behaviors of adolescents in the families and develop a program for creating the environment of the local community including schools.

• Journal of The Korean Association For Science Education
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• v.43 no.1
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• pp.37-47
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• 2023

The purpose of this study is to analyze the influence and structural relationship of variables related to science teaching professionalism. These variables set up learning organizational culture as exogenous variables and science epistemological beliefs and science teaching efficacy as endogenous variables. For this study, a survey was conducted with 499 elementary science teachers from Seoul and Gyeonggi province participating. The results of this study are as follows: Science epistemological beliefs and science teaching efficacy were found to directly affect science teaching professionalism. In addition, learning organizational culture perceived by the teachers did not show significant effects on the science teaching professionalism, but it was found that it has direct significant effects on science epistemological beliefs and science teaching efficacy. Based on the results of this study, which examines the structural relationship between learning organizational culture, science epistemological beliefs, science teaching efficacy and science teaching professionalism. we deem that it is necessary to consider internal factors of teachers as well as ways to improve learning organizational culture.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.40 no.3
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• pp.303-314
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• 2020

The hydrological characteristics of watersheds and hydraulic systems of urban and river floods are highly nonlinear and contain uncertain variables. Therefore, the predicted time series of rainfall-runoff data in flood analysis is not suitable for existing neural networks. To overcome the challenge of prediction, a NARX (Nonlinear Autoregressive Exogenous Model), which is a kind of recurrent dynamic neural network that maximizes the learning ability of a neural network, was applied to forecast a flood in real-time. At the same time, NARX has the characteristics of a time-delay neural network. In this study, a hydrological model was constructed for the Taehwa river basin, and the NARX time-delay parameter was adjusted 10 to 120 minutes. As a result, we found that precise prediction is possible as the time-delay parameter was increased by confirming that the NSE increased from 0.530 to 0.988 and the RMSE decreased from 379.9 ㎥/s to 16.1 ㎥/s. The machine learning technique with NARX will contribute to the accurate prediction of flow rate with an unexpected extreme flood condition.

• Journal of The Korean Association For Science Education
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• v.43 no.4
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• pp.389-402
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• 2023

The purpose of this study is to investigate the structural relationship between pedagogical content knowledge (PCK), grit, and teaching efficacy perceived by elementary school science teachers. Based on the results of the literature review, PCK was divided into knowledge domain and enactment domain, and these two domains were set as exogenous latent variables to investigate the structural relationship between PCK and teaching efficacy. In addition, teachers' grit was added to the structural equation model as an exogenous latent variable to investigate the effect of teachers' knowledge, enactment, and grit on teaching efficacy. Upon confirming the structural relationship between PCK and teaching efficacy, it was found that a high correlation between knowledge and enactment, and that knowledge had a greater effect on teaching efficacy than enactment. Furthermore, upon confirming the structural relationship between PCK, grit, and teaching efficacy, both knowledge and grit were found to have a statistically significant effect on teaching efficacy, while the relationship between enactment and teaching efficacy was not statistically significant. Based on the results of these studies, we discussed ways to strengthen teacher expertise and teaching efficacy in elementary school science classes and the meaning of grit in the field of teacher expertise.

• Korea journal of population studies
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• v.19 no.1
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• pp.139-159
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• 1996

This study comparatively examines a causal model of employee attatchment which focuses on employee's organizational commitment and intent to stay with an organization. This study is based on two separate studies of employee attachment among teachers : the U.S. case of the Chicago Public Schools (CPS) and the South Korean case of the Seoul Educational District (SED). The main purpose of this study is to replicate in Korea the CPS study. A revised model based on the unique characteristics of Korean teachers is also developed and estimated. The Price Mueller model of employee attachment provides the basic theoretical framework for this study. It includes five general classes of variables : 1) employee responses to work variables : job satisfaction, commitment, and intent to stay; 2) psychological stress variables: role ambiguity, role conflict, work overload, and quality of students; 3) social structural variables: autonomy, routinization, distributive justice, and legitimacy; 4) economic structural variables: pay, job security, promotional opportunities, and job opportunities; and 5) work orientation variables : career commitment, normative commitment, work motivation, affectivity, work values, and met expectations. The data was collected through questionnaire survey and a sample of 649 secondary school teachers in Seoul, South Korea, was included in the final analysis. Covariance structure analysis (LISREL) was used to estimate the causal model. The results indicate that the endogenous variables of job satisfaction and commitment play a considerably less important role than in the U.S. model in mediating the effects of the exogenous variables on intent to stay, and the model fails to explain the majority of the variance in intent to stay. In addition, the new variables added to the revised Korean model do not bave significant effects on intent to stay. The structural characteristics of the employment relationship and labor markets associated with Korean teachers forced mobility and closed external markets - are largely accountable for the major differences between the Korean and the U.S. cases. The study suggests that conceptual and empirical work on what produces employee attachment under these structural constraints needs to receive more attention in future studies.