• Journal of Engineering Education Research
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• v.27 no.2
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• pp.13-24
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• 2024

This research aims to examine the effects of engineering students' self-regulated learning strategies on writing self-efficacy, perceptions of writing feedback, and learning presence. To achieve this purpose, firstly, differences in self-regulated learning strategies, writing self-efficacy, perceptions of writing feedback, and learning presence were investigated among engineering and non-engineering students. Secondly, the effects of self-regulated learning strategies, as perceived by engineering students, on writing self-efficacy, perceptions of writing feedback, and learning presence were explored. A total of 196 engineering and non-engineering students from one university in Korea responded to a survey based on a four-variable scale. The findings were as follows: firstly, there were significant differences in self-regulated learning strategies, writing self-efficacy, perceptions of writing feedback, and learning presence by major. Secondly, positive correlations between self-regulated learning strategies, writing self-efficacy, perceptions of writing feedback, and learning presence were identified in terms of sub-factors of those variables. Thirdly, engineering students' self-regulated learning strategies predicted writing self-efficacy, perceptions of writing feedback, and learning presence. The practical implications of these findings are discussed herein, with particular attention to education for the promotion of self-regulated learning strategies and their application to writing courses, as well as diverse learning environments.

• Korean Journal of Child Studies
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• v.32 no.5
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• pp.135-150
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• 2011

The purpose of this study was to examine the interaction strategies used by typically developing boys and girls in their dealings with young children with ADHD in free play situations in inclusive classes. This was done in order to gain an in-depth understanding of the meaning of their interaction strategies. The subjects were 52 typically developing children (comprising 27 boys, 25 girls) and 3 young children with ADHD. The findings were as follows : First, the overall frequency of interaction strategies with the young children with ADHD was greater among the young female children (n = 372) than the young male children (n = 298). Second, when the utterance strategies of the male and female children were sub-categorized, both the male children (79.5%) and the female children (57.0%) mostly made use of avoidance strategies, one of the typical withdrawal strategies. Third, the interaction strategy of control represented 42.0 percent and as such was identified as the most prevalent interaction strategy utilized by the young male children studied. In the case of the young female children, obliging strategies were the most common interaction strategies representing 33.1 percent of the total used. In the light of the findings yielded from this study, some educational recommendations are provided.

• Journal of Fisheries and Marine Sciences Education
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• v.28 no.4
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• pp.1133-1142
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• 2016

The purpose of this study was to verify the effects of science classes using abductive strategies on the scientific concept understanding and meta-cognition. The subjects included two classes of sixth graders from K Elementary School in B Metropolitan City and they divided into two groups. Research group was composed of 21 students(10 boys, 11 girls) and comparative group was composed of 21 students(11 boys, 10 girls). In order to achieve aims of this study, proper contents to apply abductive strategies were selected from the first semester science curriculum for sixth graders. Also five-steps study papers were designed to elicit abductive reasoning. While the research group received 20 times of reframed science lessons using abductive strategies, the comparative group received common science lessons according to the teachers' manual. The results of this study are as follows. First, science classes using abductive strategies were effective for the scientific concept understanding. Also there were statistically significant differences between the research group and the comparative group in overall science sub-domain. In the process of hypothesis formulating, students tried to find out scientific causes thoroughly to present the optimal explanation and they concentrated on the analysis of each scientific concept. It is thought that this process contributed to better understanding in scientific concepts. Second, science classes using abductive strategies were effective for improving meta-cognition. There were statistically significant differences between the two groups and especially in monitoring that is one of sub-factors of meta-cognition. It indicates that hypothesis formulating process gave positive effect on meta-cognition by stimulating critical thinking and manifesting elaboration.

• Membrane and Water Treatment
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• v.11 no.1
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• pp.79-85
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• 2020

A single-stage deammonification with a sequencing batch reactor (SBR) that simultaneous nitritation, anaerobic ammonia oxidation (anammox), and denitrification (SNAD) occur in one reactor has been widely applied for sidestream of wastewater treatment plant. For the stable and well-balanced SNAD, a feeding strategy of influent wastewater is one of the most important operating factors in the single-stage deammonification SBR. In this study, single-stage deammonification SBR (working volume 30L) was operated to treat a high-strength ammonium wastewater (1200 mg NH₄⁺-N/L) with different feeding strategies (single feeding and nine-step feeding) under the condition without COD. Each cycle of the step feeding involved 6 sub-cycles consisted of aerobic and anoxic periods for partial nitritation (PN) and anammox, respectively. Contrary to unstable performance in the single feeding, the step feeding showed better deammonification performance (0.565 kg-N/m³/day). Under the condition with COD, however, the nitrogen removal rate (NRR) decreased to 0.403 kg-N/m³/day when the Nine-step feeding strategies had an additional denitrification period before sub-cycles for PN and anammox. The NRR was recovered to 0.518 kg-N/m³/day by introducing an enhanced multiple-step feeding strategy. The strategy had 50 cycles consisted of feed, denitrification, PN, and anammox, instead of repeated sub-cycles for PN and anammox. The multiple-step feeding strategy without sub-cycle showed the most stable and excellent deammonification performance: high nitrogen removal efficiency (98.6%), COD removal rate (0.131 kg-COD/m³/day), and COD removal efficiency (78.8%). This seemed to be caused by that the elimination of the sub-cycles might reduce COD oxidation during aerobic condition but increase the COD utilization for denitrification period. In addition, among various sensor values, the ORP pattern appeared to be applicable to monitor and control each reaction step for deammonification in the multiple-step feeding strategy without sub-cycle. Further study to optimize the number of multiple-step feeding is still needed but these results show that the multiple-step feeding strategy can contribute to a well-balanced SNAD for deammonification when treating high-strength ammonium wastewater with COD in the single-stage deammonification SBR.

• Journal of the Architectural Institute of Korea Planning & Design
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• v.34 no.3
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• pp.61-72
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• 2018

This study pursued to obtain 3 consecutive purposes. First, a conceptual model for comparing 3 constructivist teaching and learning strategies( problem-based learning[$P_bBL$], case-based learning[CBL] and project-based learning[$P_jBL$]) was developed. Relationships of these constructivist strategies with the development of expertise for learners were discussed. Second, specific differences between $P_bBL$, CBL and $P_jBL$ as applied in architectural design courses were analyzed under each of the teaching and learning category. Some analytical indexes were developed by content analysis, which are applicable effectively to reveal the differences. Based on the previous findings, third, a set of strategic guidelines for use in class were made and suggested in order to develop and improve expertise in architectural design. These guidelines were largely targeted for university design courses as well as education or reeducation of practicing architects. Expecially, combined application of $P_bBL$, CBL and $P_jBL$ was hypothesized and suggested as class management guidelines. In sum, a variety of $P_bBL$ problems, CBL cases and $P_jBL$ projects should be developed for expecting audience based on design subjects and tasks. As working domains of practicing architects, exploring/analyzing, understanding/making applications, and criticizing/self-reflecting should be considered in the development process.

• Journal of the Korean institute of surface engineering
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• v.57 no.3
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• pp.179-191
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• 2024

This study focuses on improving the photocatalytic degradation efficiency by synthesizing a TiO₂/WO₃ composite. Given the environmental significance of photocatalysis and the limitations posed by TiO₂'s large bandgap and high electron recombination rate, we explored doping, surface modification, and synthesis strategies. The composite was created using a ball mill process and heat treatment, analyzed with field emission scanning electron microscope, high resolution X-ray diffraction, Raman microscope, and UV-Vis/NIR spectrometer to examine its morphology, composition and absorbance. We found that incorporating WO₃ into the TiO₂ lattice forms a W_x-Ti_1-x-O₂ solution, with optimal WO₃ content reducing the band gap and enhancing sterilization efficiency by inhibiting the anatasese to rutile transition. This contributes to the field by offering a way to overcome TiO₂'s limitations and improve photocatalytic performance.

• Journal of Sensor Science and Technology
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• v.30 no.4
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• pp.210-217
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• 2021

Gas sensors based on semiconducting metal oxides have attracted considerable attention for various applications owing to their facile, cheap, and small-scale manufacturing processes. Hematite (α-Fe₂O₃) is widely considered as a promising candidate for a gas-sensing material owing to not only its abundance in the earth's crust and low price but also its chemical stability and suitable bandgap energy. However, only a few studies have been performed in this direction because of the low gas response and sluggish response of hematite-based gas sensors. Nanostructures present a representative solution to both overcome these disadvantages and exploit the desirable features to produce high-performance gas sensors. However, several challenges remain for adopting gas sensors based on metal oxide nanostructures, such as improving cost efficiency and facilitating mass production. This review summarizes the recent studies on gas sensors based on hematite nanostructures. It also provides useful insights into various strategies for enhancing the gas-sensing properties of gas sensors based on hematite nanostructures.

• Corrosion Science and Technology
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• v.22 no.6
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• pp.408-418
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• 2023

In this study, we synthesized and characterized garnet-type Li_7-xAl_xLa₃Zr_2-(5/4)yNbyO₁₂ (LALZN) solid electrolytes for all-solid-state battery applications. Our novel approach focused on enhancing ionic conductivity, which is crucial for battery efficiency. A systematic examination found that co-doping with Al and Nb significantly improved this conductivity. Al³⁺ and Nb⁵⁺ ions were incorporated at Li⁺ and Zr⁴⁺ sites, respectively. This doping resulted in LALZN electrolytes with optimized properties, most notably enhanced ionic conductivity. An optimized mixture with 0.25 mol each of Al and Nb dopants achieved a peak conductivity of 1.32 × 10^-4 S cm^-1. We fabricated symmetric cells using these electrolytes and observed excellent charge-discharge profiles and remarkable cycling longevity, demonstrating the potential for long-term application in battery systems. The garnet-type LALZN solid electrolytes, with their high ionic conductivity and stability, show great potential for enhancing the performance of all-solid-state batteries. This study not only advances the understanding of effective doping strategies but also underscores the practical applicability of the LALZN system in modern energy storage solutions.

• Journal of Sensor Science and Technology
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• v.29 no.6
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• pp.382-387
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• 2020

Hydrogen (H₂) is considered as a new clean energy resource for replacing petroleum because it produces only H₂O after the combustion process. However, owing to its explosive nature, it is extremely important to detect H₂ gas in the ambient atmosphere. This has triggered the development of H₂ gas sensors. 2-dimensional (2D) graphene has emerged as one of the most promising candidates for chemical sensors in various industries. In particular, graphene exhibits outstanding potential in chemoresistive gas sensors for the detection of diverse harmful gases and the control of indoor air quality. Graphene-based chemoresistive gas sensors have attracted tremendous attention owing to their promising properties such as room temperature operation, effective gas adsorption, and high flexibility and transparency. Pristine graphene exhibits good sensitivity to NO₂ gas at room temperature and relatively low sensitivity to H₂ gas. Thus, research to control the selectivity of graphene gas sensors and improve the sensitivity to H₂ gas has been performed. Noble metal decoration and metal oxide decoration on the surface of graphene are the most favored approaches for effectively controlling the selectivity of graphene gas sensors. Herein, we introduce several strategies that enhance the sensitivity of graphene gas sensors to H₂ gas.

• Journal of Environmental Science International
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• v.31 no.1
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• pp.9-21
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• 2022

Today's cities require deeper understanding of the thermal environment and PM₁₀ as their management becomes more critical. Based on these circumstances, this study investigated the Granger causality between the thermal environment and PM₁₀ of the 25 districts of Seoul, the most populous and urbanized city in Korea. The results of the Granger causality test on the thermal environment and PM₁₀ were classified into 12 types. Except for type 12, the temperature and urban island heat intensity of the other 11 types operated as a Granger-cause to each other in both directions. Temperature operates as a Granger-cause of urban island heat intensity in type 12. The PM₁₀ level and urban pollution island intensity operated as a Granger-cause to each other in all districts. For types 1 and 2, thermal environment operated as a Granger-cause to PM₁₀ in one direction, and type 3-type 12 confirmed that thermal environment and PM₁₀ operated as a Granger-cause in both directions. Findings reveal the intricate causalities between thermal environment and PM₁₀ at the district level and suggest mitigation strategies that are more location based.