• 한국초등수학교육학회지
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• 제21권1호
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• pp.1-22
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• 2017

연산법칙은 산술 학습을 위해 계산 원리 파악 및 효과적인 계산 전략 개발에 필수적인 것으로 간주되며, 초등학교에서 초기 대수 지도에 대한 긍정적 견해와 더불어 연산에 대한 직관적 관념 및 구조적 이해를 위해 연산법칙 자체에 대한 탐구가 요구된다. 따라서 연산법칙에 대한 이해가 부족할 경우, 연산법칙을 가정한 후속 학습시 학습 곤란과 오개념 형성을 유발할 우려가 있다. 이에 본 연구는 초등학교 수학 교과서에서 연산법칙이 다루어지는 특성을 분석함으로써 연산법칙의 바람직한 지도 방안을 탐색하는 것을 목적으로 한다. 이를 위해 우리나라 교육과정기에 따른 교과서 분석을 통해 어떤 연산법칙이 어느 시기에 어떤 방법으로 지도되어 왔는지를 비교하고 연산법칙을 가정하는 내용 전개 사례를 추출하였다. 그 결과에 대한 논의에 기초하여 초등학교 수학에서 연산법칙의 지도 필요성과 가능성을 확인하고 지도 방안에 대한 시사점을 도출하였다.

• 호남수학학술지
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• 제38권4호
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• pp.675-683
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• 2016

We give the representation of Fibonacci quaternions for convenient calculus. We research the corresponding properties of Fibonacci quaternions and some examples of a function with values in modified Fibonacci quaternions.

• 한국초등과학교육학회지:초등과학교육
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• 제35권3호
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• pp.326-335
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• 2016

The purpose of this study is to devise the concept of properties of the light on learning progressions for 3-6 grade students in the elementary school. For the purpose, this study creates a construct map of the properties of the light. Ordered multiple-choice items were developed in view of the construct map and presented to 200, 3~6 grade students in the elementary school. A partial credit model of Rasch model was used to analyze the results of those items, and the learning progressions was devised from the analysis results. The study can be summarized as follows: the construct modeling approach was used to devise the properties of light on learning progressions. As a result, the concept was selected for the core standards of construct map. Based on the construct map, the multiple-choice items were developed for students' conceptual understanding. The items were analyzed using the partial credit model, and the analysis findings showed that they were appropriate to assess students about their level of understanding of the properties of light. Finally, learning progressions were devised with the use of item analysis results.

• 한국안전학회지
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• 제19권4호
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• pp.25-30
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• 2004

Unidirectional fiber-metal matrix composites have superior mechanical properties along the longitudinal direction. However, the applicability of continuous fiber reinforced MMCs is somewhat limited due to their relatively poor transverse properties. Therefore, the transverse properties of MMCs are significantly influenced by the properties of the fiber/matrix interface. In this study, the interfacial stress states of transversely loaded unidirectional fiber reinforced metal matrix composites investigated by using elastic-plastic finite element analysis. Different fiber volume fractions $(5-60\%)$ were studied numerically. The interface was treated as thin layer (with different properties) with a finite thickness between the fiber and the matrix. The fiber is modeled as transversely isotropic linear-elastic, and the matrix as isotropic elastic-plastic material. The analyses were based on a two-dimensional generalized plane strain model of a cross-section of an unidirectional composite by the ANSYS finite element analysis code.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2006년도 춘계 학술발표회 논문집
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• pp.768-776
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• 2006

Recently in spite of Development of Investigation machine, in Application of Geotechnical Properties by empirical recommendation to the Slope Stability Analysis. It is generally Application of convenience and conservative Geotechnical Properties by Borehole Shear Test(BST) in Representative Zone that Non-Division of Increase as the depth of Strength Parameters In Deep Weathered Zone. Therefore, it is become environment pollution and Non-Economical Slope Design to Application of convenience and conservative Geotechnical Properties. The production mechanism of Deep Weathered Zone is tend to Weathering Degree low and Strength increase by increase as the depth. it is realistic design that Division of Deep Weathered Zone and application Geotechnical Properties of Each Layer. In this Paper, Determined The Relationship of Strength Parameters between Standard Penetration Test(SPT), Borehole Shear Test(BST) and empirical recommendation also Applyed each strength parameters of divided zone to the Slope Stability Analysis by continuous Borehole Shear Test(BST) in Deep Weathered Zone during design of The 2nd Bridge Connection Road of Incheon International Airport.

• 한국철도학회논문집
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• 제8권2호
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• pp.188-194
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• 2005

Aging characteristics of glass fabric/phenolic composites for tilting train subjected to combined environmental aging factors were investigated. A 2.5KW accelerated aging tester with a xenon-arc lamp was used to provide environmental aging factors such as temperature, moisture, and ultraviolet. A series of aging tests were conducted up to 3000 hours and several types of specimens were prepared along the warp direction and the fill direction. Mechanical degradations for tensile, flexural, and shear properties were evaluated as a function of exposure times through a material testing system. Thermal analysis properties such as storage shear modulus, loss shear modulus, and tan 3 were measured through a dynamic mechanical analyzer. Finally exposed surfaces of the composites were examined using a scanning electron microscope. According to the experimental results, mechanical properties and thermal analysis properties of glass fabric/phenolic composites were found to be slightly degraded as a function of exposure times due to combined environmental effects.

• 한국건축시공학회지
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• 제4권3호
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• pp.143-151
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• 2004

The purpose of this study is development of technique to use cementitious powder as recycle cement produced from deteriorated Concrete waste which has a large quantity of calcium carbonate. Therefore, after having theoretical consideration based on the properties of high-heated concrete and concerning about neutralization of Concrete, we analysis chemical properties of ingredients of cementitious powder. After making origin cement paste, then processing the accelarated carbonation, we consider the properties of hydration and chemical properties of cementitious powder under various temperature conditions. As a result of the thermal analysis, the $CaCO_3$ content of cementitious powder would affect decision of heat temperature to recover its hydrated ability because $CaCO_3$ content is increased when neutralization is progressed. And as a result of XRD analysis, in case of origin powder of non-neutralized paste, CaO peak is found at $700^{\circ}C$. but, heat temperature to generate CaO would increase when the content of neutralized ingredients is increased. Finally, recycle cement heated at $700^{\circ}C$ 120min. shows the best compressive strength when the content of neutralized ingredients in recycle cement is less then 50%.

• Composites Research
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• 제26권1호
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• pp.54-59
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• 2013

This study deals with effect of plasma treatment on the properties of unidirectional ligno cellulosic fabric Hildegardia Populofolia (HDP) fabric. Thermal stability of the fabric was determined by differential scanning calorimetry (DSC) and Thermo gravimetric analysis (DSC). Morphological properties was analyzed by SEM analysis and found that the surface was rough upon plasma treatment which provides good interfacial adhesion with matrix during composite fabrication. Thermal stability and mechanical properties of the plasma treated fabric slightly increases compare to alkali and untreated fabric. It was observed that tensile properties of the fabric increases upon plasma treatment due to the formation of rough surface. SEM analysis indicates formation of rough surface on plasma treatment which helps in increasing the interfacial interaction between the matrix (hydrophobic) and fabric (hydrophilic).

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2003년도 학술.기술논문 발표회
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• pp.77-82
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• 2003

The purpose of this study is development of technique to use cementitious powder as recycle cement produced from deteriorated Concrete waste which has a large quantity of calcium carbonate. Therefore, after having theoretical consideration based on the properties of high-heated concrete and concerning about neutralization of Concrete, we analysis chemical properties of ingredients of cementitious powder. After making origin cement paste, then processing the accelarated carbonation, we consider the properties of hydration and chemical properties of cementitious powder under various temperature conditions. As a result of the thermal analysis, the CaCo3 content of cementitious powder would affect decision of heat temperature to recover its hydrated ability because CaCo3 content is increased when neutralization is progressed. And as a result of XRD analysis, in case of origin powder of non-neutralized paste, CaO peak is found at 700℃. but, heat temperature to generate CaO would increase when the content of neutralized ingredients is increased. Finally, recycle cement heated at 700℃ shows the best compressive strength when the content of neutralized ingredients in recycle cement is less then 50%. However, it would be quite difficult to manage quality of recycle cement according to recycling points of various concrete waste.

• 한국압력기기공학회 논문집
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• 제8권2호
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• pp.7-13
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• 2012

A spacer grid which is one of the most important structural components in a pressurized water reactor fuel is an interconnected array of slotted grid straps, welded at the intersections to form an egg-crate structure. The spacer grid is required to not only protect fuel rods stably but also have sufficient lateral crush strength for the sake of enabling shut-down of the nuclear reactor during abnormal operating environments. Then, the lateral crush strength of the spacer grid is closely related with welding quality of the spacer grid. Previous research on the crush strength analysis of the spacer grid had been performed using only parent material properties. In this study, to investigate the effect on the crush strength of the spacer grid when used mechanical properties in weld zone instead of parent material properties, crush strength analysis considering mechanical properties in weld zone obtained from the instrumented indentation technique was performed and compared the results with the previous research.