• 대한지구과학교육학회지
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• 제4권1호
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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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• 제66권4호
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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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• 제65권4호
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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.

• 한국초등과학교육학회지:초등과학교육
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• 제27권3호
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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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• 제48권4호
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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.

• 소성∙가공
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• 제27권1호
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• pp.60-65
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• 2018

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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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.

• 대한수학교육학회지:수학교육학연구
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• 제27권3호
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• pp.557-580
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• 2017

본 연구는 수학영재의 집단창의성 발현 모델을 이론적으로 구안하고, 이를 실제 수업에 적용한 결과를 분석하여 모델을 확인하고 정교화하는 것을 목적으로 한다. 영역 일반적인 집단창의성에 대한 선행연구와 수학영재의 창의성에 대한 선행연구를 고찰하여 집단창의성 발현 모델을 구안하였다. 또한 이 모델을 수학영재학급 수업에 적용하여 학생들이 보인 반응을 분석하였다. 분석 결과, 집단창의성 발현 모델의 각 단계에 따른 수학영재의 반응과 집단창의성에 작용하는 주요 요인을 확인하였으며, 수학적 정당화를 위해 추측 또는 문제해결 아이디어 공유 단계로 되돌아가는 과정과 집단 수준의 창의적 시너지가 일어날 수 있는 발생 및 긴장 상태에서 추측 또는 문제해결 아이디어 공유단계로 되돌아가는 과정을 추가적으로 발견하였다.

• 한국초등수학교육학회지
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• 제21권3호
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• pp.505-530
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• 2017

본 연구는 수학영재의 집단창의성 발현 과정과 산출을 분석하여 어떤 특성이 있는지를 확인하고, 집단창의성 발현을 방해하는 과정 손실의 원인을 파악하는 것을 목적으로 하였다. 이를 위해 수학영재학급 수업에 집단창의성 발현을 위한 단계를 적용하였고, 수 체계의 성질과 모듈로 산술을 주제로 하여 수업을 진행하였다. 연구방법으로는 학생들이 보인 반응과 산출의 사례를 질적으로 분석하는 사례연구를 진행하였고, 집단창의성 발현 과정과 산출, 과정 손실의 원인에 대한 선행연구 내용을 기준으로 분석하였다. 그 결과, 집단의 과정에서 창의적 시너지가 나타날 수 있는 상보적, 발생, 긴장 상태와 기여의 결합이 나타나는 방식인 수집, 연결, 선택, 변형, 집단의 창의적 산출의 특성인 집단 유창성, 집단 융통성, 집단 독창성, 집단 정교성이 관련된 것끼리 이어질 수 있음을 확인하였다. 그리고 집단 수준의 창의적 시너지가 나타날 수 있는 상보적, 발생, 긴장 상태에서 과정 손실의 인지적 원인과 사회 동기적 원인이 나타나는 경우를 확인하였다. 분석 결과를 통해 집단창의성 발현을 위한 수학영재학급 수업 설계 시에 고려해야 할 점에 대해 제안하였다.

• 한국주조공학회지
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• 제40권2호
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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.