• 한국재료학회지
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• 제20권12호
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• pp.681-685
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• 2010

The application of flip chip technology has been growing with the trend of miniaturization of electronic packages, especially in mobile electronics. Currently, several types of adhesive are used for flip chip bonding and these adhesives require some special properties; they must be solvent-free and fast curing and must ensure joint reliability against thermal fatigue and humidity. In this study, imidazole and its derivatives were added as curing catalysts to epoxy resin and their effects on the adhesive properties were investigated. Non-isothermal DSC analyses showed that the curing temperatures and the heat of reaction were dependent primarily on the type of catalyst. Isothermal dielectric analyses showed that the curing time was dependent on the amount of catalysts added as well as their type. The die shear strength increased with the increase of catalyst content while the Tg decreased. From this study, imidazole catalysts with low molecular weight are expected to be beneficial for snap curing and high adhesion strength for flip chip bonding applications.

• 한국환경교육학회지:환경교육
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• 제17권1호
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• pp.12-24
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• 2004

The purpose of this study was to analyze and compare Korean middle school-level environmental education(EE) textbooks. More specifically, these analyses and comparisons were designed to explore the extent to which environmental investigation skills were addressed in these EE textbooks (i.e., curriculum inclusion), as well as the manner in which these skills were to be taught and learned (i.e., instructional approaches). To analyze EE textbooks, the researchers developed a 'Curriculum Analysis Chart' that include six skill clusters and four instructional strategies. This analytic chart permitted the researchers to determine which skills were featured in selected textbooks, as well as which skill-oriented instructional strategies accompanied each of those skills. The chart was revised several times through pilot analyses. Using the final version of this chart, the researchers analyzed and then compared the three textbooks. This analysis indicated that the Korean middle school-level EE textbooks were designed to support conceptual learning and understanding of environment and environmental problems/issues (i.e., content-oriented), and were designed to support skill learning to a moderate degree. On the basis of textbooks analysis, the researchers offered several recommendations for future research, and for educational practices in EE.

• 한국세라믹학회지
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• 제32권7호
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• pp.809-816
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• 1995

Ti1-xAlxN films were successfully deposited on high speed steel and silicon wafer by plasma-assisted chemical vapor deposition using a TiCl4/AlCl3/N2/Ar/H2 gas mixture. Plasma process enabled N2 gas to nitride AlCl3, which is not possible in sense of thermodynamics. XPS analyses revealed that the deposited layer contained Al-N bond as well as Ti-N bond. Ti1-xAlxN films were polycrystalline and had single phase, B1-NaCl structure of TiN. Interplanar distance, d200, of (200) crystal plane of Ti1-xAlxN was, however, decreased with Al content, x. Al incorporation into TiN caused the grain size to be finer and changed strong (200) preferred orientation of TiN to random oriented microstructure. Those microstructural changes with Al addition resulted in the increase of micro-hardness of Ti1-xAlxN film up to 2800Kg/$\textrm{mm}^2$ compared with 1400Kg/$\textrm{mm}^2$ of TiN.

• 아동학회지
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• 제31권4호
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• pp.91-110
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• 2010

The purpose of this study was to develop a valid and reliable early childhood teacher efficacy scale. As part of this process, the final version of the early childhood teacher efficacy scale was examined in order to reflect the characteristics of the subjects who participated in this study, namely, 598 in-service teachers employed at kindergartens and child care centers. Our data was analyzed according to both the reliability and validity of the scale. the main results of this study were as follows. The overall internal consistency was relatively high (Cronbach's ${\alpha}$ = .91~.93). In addition, the content reliability was examined by a panel of experts in the field. The results of the factor analyses identified 6 sub-constructs with 59 items, thus clearly establishing the construct validity. Moreover, the concurrent validity of this scale was established. The results of correlational and t-test analyses found that the constructs of this scale reflected the characteristics of early childhood teachers.

• 대한수학교육학회지:학교수학
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• 제8권3호
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• pp.341-364
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• 2006

본 논문은 수학과 교육과정에서 최근 지속적으로 강조되어 온 문제해결과 관련하여 제7차 초등학교 교육과정에서 제시하고 있는 내용을 살펴보고, 이와 관련하여 현재 개정 시안에서 논의되고 있는 내용을 분석하였다. 또한 수학 교과서와 익힘책에서 교육과정의 기본적인 취지를 어떻게 구현하고 관련 세부 내용을 어떻게 구체화하고 있는지 알아보기 위해, 문제해결전략, 문제영역, 문제유형별로 문제해결 관련 내용을 상세하게 분석하였다. 이를 토대로 문제해결과 관련하여 차기 교육과정 및 교과용 도서 개발에 기초적인 자료 및 시사점을 제공하고자 한다.

• Environmental Engineering Research
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• 제18권1호
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• pp.37-43
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• 2013

Water distribution pipes installed underground have potential risks of pipe failure and burst. After years of use, pipe walls tend to be corroded due to aggressive soil environments where they are located. The present study aims to assess the degree of external corrosion of a distribution pipe network. In situ data obtained through test pit excavation and direct sampling are carefully collated and assessed. A statistical approach is useful to predict severity of pipe corrosion at present and in future. First, criteria functions defined by discriminant function analysis are formulated to judge whether the pipes are seriously corroded. Data utilized in the analyses are those related to soil property, i.e., soil resistivity, pH, water content, and chloride ion. Secondly, corrosion factors that significantly affect pipe wall pitting (vertical) and spread (horizontal) on the pipe surface are identified with a view to quantifying a degree of the pipe corrosion. Finally, a most reliable model represented in the form of a multiple regression equation is developed for this purpose. From these analyses, it can be concluded that our proposed model is effective to predict the severity and rate of pipe corrosion utilizing selected factors that reflect the fuzzy soil environment.

• Mycobiology
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• 제44권4호
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• pp.338-342
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• 2016

The culture filtrate of Lentinula edodes shows potent antimicrobial activity against the plant pathogenic bacteria Ralstonia solanacearum. Bioassay-guided fractionation was conducted using Diaion HP-20 column chromatography, and the insoluble active compound was not adsorbed on the resin. Further fractionation by high-performance liquid chromatography (HPLC) suggested that the active compounds were organic acids. Nine organic acids were detected in the culture filtrate of L. edodes; oxalic acid was the major component and exhibited antibacterial activity against nine different phytopathogenic bacteria. Quantitative analysis by HPLC revealed that the content of oxalic acid was higher in the water extract from spent mushroom substrate than in liquid culture. This suggests that the water extract of spent L. edodes substrate is an eco-friendly control agent for plant diseases.

• Earthquakes and Structures
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• 제8권1호
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• pp.185-204
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• 2015

This study investigates the impact of the earthquake incident angle on the structural demand and the influence of ground motion selection and scaling methods on seismic directionality effects. The structural demand produced by Non-Linear Time-History Analyses (NLTHA) varies with the seismic input incidence angle. The seismic directionality effects are evaluated by subjecting four three-dimensional reinforced concrete structures to different scaled and un-scaled records oriented along nine incidence angles, whose values range between 0 and 180 degrees, with an increment of 22.5 degrees. The results show that NLTHAs performed applying the ground motion records along the principal axes underestimate the structural demand prediction, especially when plan-irregular structures are analyzed. The ground motion records generate the highest demand when applied along the lowest strength structural direction and a high energy content of the records increases the structural demand corresponding to this direction. The seismic directionality impact on structural demand is particularly important for irregular buildings subjected to un-scaled accelerograms. However, the orientation effects are much lower if spectrum-compatible combinations of scaled records are used. In both cases, irregular structures should be analyzed first with pushover analyses in order to identify the weaker structural directions and then with NLTHAs for different incidence angles.

• Earthquakes and Structures
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• 제10권3호
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• pp.495-521
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• 2016

Ancient monuments of Greek and Roman classical architecture usually consist of multi-drum columns that are constructed of stone blocks placed on top of each other. Several research studies deal with the seismic behaviour of such structures, since earthquakes are common causes of destruction of such monuments. This paper investigates the effect of multiple earthquakes on the seismic performance of multi-drum columns, through numerical simulations and parametric analyses. The Discrete Element Method and an appropriate contact model have been implemented in a specially developed software application that is able to efficiently perform the necessary simulations in two dimensions. Specifically, various strong ground excitations are used in series for the computation of the collective final deformation of multi-drum columns. In order to calculate this cumulative deformation for a series of ground motions, the individual deformation of the column for each excitation is computed and then used as initial conditions for the next earthquake excitation. Various multi-drum columns with different dimensions are also considered in the analyses in order to examine how the geometric characteristics of columns can affect their seismic sequence behaviour, in combination with the excitation frequency content.

• 임상간호연구
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• 제29권2호
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• pp.186-197
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• 2023

Purpose: The purpose of this study was to develop a scale to measure professionalism of clinical nurses and evaluate the reliability and validity of the scale. Methods: DeVellis's scale-development eight steps were applied. The initial items were developed through a literature review and discussion with investigators, and the content validity was verified by seven experts. The data were collected from 250 hospital nurses for exploratory factor analysis and 217 hospital nurses for confirmatory factor analysis. Exploratory and confirmatory factor analyses were utilized to assess the construct validity. Cronbach's ⍺ was used to test the internal consistency reliability. Results: The results of the exploratory and confirmatory factor analyses showed that the scale comprised four factors: professional skill(eight items), sense of ethics (five items), knowledge-seeking activities (four items), and autonomy(three items). The four-factor structure was validated (x 2 =600.85 p<.001, GFI=.88, CFI=.84, RMSEA=.07), and Cronbach's ⍺ for the total scale was .84. Conclusion: The study results showed satisfactory reliability and validity of the professionalism measurement scale for clinical nurses. This scale has potential as an appropriate instrument for measuring clinical nurse professionalism.