• Journal of the Korean Society of Earth Science Education
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• v.4 no.1
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• pp.43-56
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• 2011

The purpose of this study is to examine the effects of small group inquiry skills on improving science process skills and attitudes toward science in elementary school science. The research questions of this study were as follows. First, effects of small group inquiry skills on improving science process skills in elementary school science. Second, effects of small group inquiry skills on improving attitudes toward science in elementary school science. The subjects of this study is two classes from 6th grade elementary classes in Busan. The experiment class practiced small group inquiry skills, while the control class practiced self inquiry. To verify the effect of the experiment, ANOVA was conducted. The main findings of this study are as follows. First, the small group inquiry skills gave a significant influence on increasing the science process skills, including the basic science process skills and the integrated science process skills, of students. Especially, among subordinate factors of science process skills between groups, it was effective to increase abilities of observing, reasoning, interpreting data, formulating hypothesis. It is necessary for teachers to make an effort to teach according to steps of the small group inquiry skills and to support inquiry activities, in order to increasing the science process skills. However, frequency of additional lessons have a little influence on increasing the science process skills. Second, there is meaningful change in the attitudes toward science for those who studied the small group inquiry skills. Also, they affected subordinate factors of the attitudes toward science, like the attitudes toward science inquiry, the happiness about science class. This study shows that the small group inquiry skills give a positive influence on the science process skills and attitudes toward science in elementary school science.

• Archives of Metallurgy and Materials
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• v.66 no.4
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• pp.1013-1018
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• 2021

In this paper, as a purpose to apply the supersaturated solid-solutionized Al-9Mg alloy to the structural sheet parts of automotive, tensile tests were conducted under the various conditions and a constitutive equation was derived from the tensile test results. Al-9Mg alloy was produced using a special Mg master alloy containing Al₂Ca during the casting process and extruded into the sheet. In order to study the deformation behavior of Al-9Mg alloy in warm temperature forming environments, tensile tests were conducted under the temperature of 373 K-573 K and the strain rate of 0.001/s~0.1/s. In addition, by using the raw data obtained from tensile tests, a constitutive equation of the Al-9Mg alloy was derived for predicting the optimized condition of the hot stamping process. Al-9Mg alloy showed uncommon deformation behavior at the 373 K and 473 K temperature conditions. The calculated curves from the constitutive equation well-matched with the measured curves from the experiments particularly under the low temperature and high strain rate conditions.

• Archives of Metallurgy and Materials
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• v.65 no.4
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• pp.1255-1259
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• 2020

This paper aims to investigate the microstructural evolution and mechanical properties of hot-deformed AlMg4 alloys with Mn, Fe, and Si as the main impurities. For this purpose, solidification behavior and microstructural evolution during hot-rolling and heat-treatment processes are investigated by using theoretical calculations and experimental characterization. The crystallization and morphological transformation of intermetallic Al₃Fe, Al₆Mn, and Mg₂Si phases are revealed and discussed in terms of the variation in chemical composition. Following a homogenization heat-treatment, the effect of heat treatment on the intermetallic compounds is also investigated after hot-rolling. It was revealed that the Mg₂Si phase can be broken into small particles and spherodized more easily than the Al₃Fe intermetallic phase during the hot-rolling process. For the Mn containing alloys, both yield and ultimate tensile strength of the hot-rolled alloys increased from 270 to 296 MPa while elongation decreased from 17 to 13%, which can be attributed to Mn-containing intermetallic as well as dispersoid.

• Journal of Korean Elementary Science Education
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• v.27 no.3
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• pp.233-243
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• 2008

The purpose of this study is to examine the effect of higher grades in elementary the science process skill and scientific attitudes by creative problem solving. To verify research problem, the subject of this study were sixth-grade students selected from two classes of an elementary school located in Ulsan : the experimental group is composed of thirty-two students who were participated in Treffinger's CPS teaching model situation, and the other is composed of thirty-two students(control group) who were participated in teacher map based learning situation. During six weeks, the CPS teaming-based instruction was executed In th experimental group while the teacher map based instruction in controled group. Post-test showed following results: first, the experimental group showed a significant improvement in the science process skill compared th the control group. Second, the experimental group did not showed a significant improvement in the science process skill compared th the control group. In conclusion, Treffinger's CPS teaching model was more effective than the teacher map based teaching model on science process skill. However, since the study has a limit on an object of the study and the applied curriculum, the additional studies need to be conducted with an extended comparative group and curriculum.

• Nuclear Engineering and Technology
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• v.48 no.4
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• pp.997-1001
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• 2016

Conductive ceramics are being developed to replace current Pt anodes in the electrolytic reduction of spent oxide fuels in pyroprocessing. While several conductive ceramics have shown promising electrochemical properties in small-scale experiments, their long-term stabilities have not yet been investigated. In this study, the chemical stability of conductive $La_{0.33}Sr_{0.67}MnO_3$ in $LiCl-Li_2O$ molten salt at $650^{\circ}C$ was investigated to examine its feasibility as an anode material. Dissolution of Sr at the anode surface led to structural collapse, thereby indicating that the lifetime of the $La_{0.33}Sr_{0.67}MnO_3$ anode is limited. The dissolution rate of Sr is likely to be influenced by the local environment around Sr in the perovskite framework.

• Transactions of Materials Processing
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• v.27 no.1
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• pp.60-65
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• 2018

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1702-1703
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• 2011

MEMS 소자의 Wafer level Package 관련하여 Deep cavity를 가진 Cap Wafer와 Polymer bonding 중 cavity 단차로 인한 Polymer Patterning 및 접합 불량의 어려움을 극복할 수 있는 새로운 공정 flow를 제안하였다. Cavity를 형성할 때 사용하는 Si deep etching Mask인 기존의 Photoresist를 접합용 감광성 Polymer로 대체하고, cavity 형성 후, 별도의 추가 공정 없이 이 Polymer를 이용해 Wafer bonding을 진행하였다. 이를 통해 cavity 단차에 따른 문제를 해결함과 동시에 공정이 단순하고 제작 비용이 저렴하며, 신뢰성 있는 Wafer level Package를 구현하였다.

• Journal of Educational Research in Mathematics
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• v.27 no.3
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• pp.557-580
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• 2017

The purpose of this study is developing the manifestation process model of group creativity among mathematically gifted students. Therefore, I designed the manifestation process model of group creativity by researching the existing literatures on group creativity and mathematical creativity. The manifestation process model of group creativity was applied to mathematically gifted students' class. By analyzing students' response, the manifestation process model of group creativity was improved and concretized. In conclusion, the process of a combination of contributions was concretized and the major variables on group creativity such as a diversity, conflict, emotionally supportive environment and social comparison were verified. In addition, some reflective processes was discovered from a case study.

• Journal of Elementary Mathematics Education in Korea
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• v.21 no.3
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• pp.505-530
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• 2017

Although mathematically gifted students have potential and creative productivity, they might not manifest group level creative synergy. To manifest group creativity among them, the manifestation process should be facilitated and the process losses should be minimized. The purpose of this study is looking for the method to facilitate the manifestation process of group creativity and minimize the process losses of it. To do this, a case study method was adopted. The products and process losses of the manifestation process of group creativity was analysed. In conclusion, the processes and products of group creativity were concretized and the process losses were analysed by social/motivational and cognitive factors. In addition, the justification and agreement were necessary for the manifestation process of group creativity among mathematically gifted students.

• Journal of Korea Foundry Society
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• v.40 no.2
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• pp.34-42
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• 2020

The effects of the initial balancing pressure, filling pressure and maximum build-up pressure on the casting characteristics of the thick-wall thickness casting during the counter-pressure casting process were investigated. Water model experiment and a computer simulation were carried out to evaluate the characteristics during the filling and solidification stages in counter-pressure casting (CPC); as a reference, the low-pressure casting (LPC) process was used. The average dendrite cell size decreased with an increase in the solidification rate and maximum build-up pressure. A turbulent flow occurred during the filling stage of the LPC process, resulting in the formation of inner gas, while a lamellar flow pattern dominated during the CPC process and was more evident with an increase in the initial balancing pressure, improving the mechanical properties of the castings.