Huang C.,National Changhua University of Education
Cyberpsychology, Behavior, and Social Networking | Year: 2010
This meta-analysis examines the relationship between various Internet uses and measures of psychological well-being, including depression, loneliness, self-esteem, and life satisfaction. Forty studies represent a total sample of 21,258 participants and yield a data of 43 independent correlations. The mean correlation was -0.0504 for the fixed-effects model and r? =?-0.0385 for the random-effects model, indicating a small detrimental effect of Internet use on psychological well-being. According to the random-effects model, the effect of all moderators, including type of Internet use, indicator of well-being, quality of Internet use measure, and participant age and gender were insignificant. Since these moderators failed to explain the variation in the relationship between Internet use and psychological well-being, future investigations should consider the possible sources of these differences. Copyright 2010, Mary Ann Liebert, Inc.
Lee S.W.-Y.,National Changhua University of Education
Computers and Education | Year: 2013
The main purpose of this study was to understand the relationships between students' approaches to learning, their perceptions of online discussions, students' contributions in asynchronous discussions, and their academic performance. Two sets of questionnaires were used for understanding students' approaches of learning and perceptions of online discussions. The online postings from seven weeks of discussions were coded into three major categories: Initiation, Elaborated Response (ER), and Response with Resources (RWR). The results showed, first, some aspects of students' perceptions influenced the numbers of ERs and RWRs. Secondly, students' contributions to Initiation messages and RWR significantly related to deep motivation and deep strategies; however, the numbers of these two types of messages were negatively correlated to surface strategies. Finally, cluster analysis revealed three distinct groups who scored significantly different in almost all aspects of approaches to learning and perceptions of online discussions. Students in the cluster who adopted deep approaches and scored highest in the perception scales outperformed students in the other two clusters, both in terms of the number of ER messages and academic performance. Pedagogical implications for teaching with online discussions are discussed in this study. © 2013 Elsevier Ltd. All rights reserved.
Liu S.-H.,National Changhua University of Education
Computers and Education | Year: 2011
In Taiwan, teachers are expected to integrate technology into instruction with learner-centered beliefs; however, teacher beliefs and practices may differ. The contextual factors influencing this inconsistency must be identified. This study first examines the relationship between pedagogical beliefs of teachers and teaching activities, and further identifies differences between teacher beliefs and teaching activities of Taiwanese teachers in each factor associated with technology integration. In total, 1139 elementary school teachers filled out a set of questionnaires that collected information about teacher pedagogical beliefs, frequent teaching activities, and factors associated with technology integration. Chi-square test results reveal that most Taiwanese teachers held learner-centered belief, but did not integrate constructivist teaching with technology. This analytical result confirms the conflict between teacher beliefs and teaching activities. Two-way analysis of variance results demonstrate that external requests and student test scores were principal considerations for constructivist teachers. Constructivist teaching with technology to enhance student achievement should influence teacher beliefs and practices. The study recommends that future studies conduct a cross-nation comparison to elucidate the factors associated with technology integration in different cultural contexts. © 2010 Elsevier Ltd. All rights reserved.
Huang S.-C.,National Changhua University of Education
Applied Soft Computing Journal | Year: 2011
Financial time series are nonlinear and non-stationary. Most financial phenomena cannot be clearly characterized in time domain. Therefore, traditional time domain models are not very effective in financial forecasting. To address the problem, this study combines wavelet analysis with kernel partial least square (PLS) regressions for stock index forecasting. Wavelet transformation maps time domain inputs to time-frequency (or wavelet) domain, where financial characteristics can be clearly identified. Because of the high dimensionality and heavy multi-collinearity of the input data, a wavelet domain kernel PLS regressor is employed to create the most efficient subspace that maintains maximum covariance between inputs and outputs, and to perform final forecasting. Empirical results demonstrate that the proposed model outperforms traditional neural networks, support vector machines, GARCH models, and has significantly reduced the forecasting errors. © 2011 Elsevier B.V. All rights reserved.
Juan Y.-L.,National Changhua University of Education
IEEE Transactions on Power Electronics | Year: 2011
In this paper, a novel ac/dc interface with an integrated controller is proposed for the microscale wind power generation system (WPGS). The proposed interface is mainly composed of a dynamic maximum power point tracking (MPPT) control and a half-controlled single-stage rectifier with an integrated control. The half-controlled single-stage rectifier is proposed to replace the widely used two-stage converter for improving the current total harmonics distortion (THD) as well as the efficiency. The analytic expressions of the duty ratios for controlling the rectifier are also derived. Moreover, the dynamic response of the wind turbine and the extracted wind power are enhanced by the integrated dynamic MPPT control. Finally, from the experimental results, it can be seen that the current THD is reduced to around 5, and the total efficiency is increased by about 1215 depending on the wind speed variations. © 2011 IEEE.