• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.521-527
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• 1997

Irregular shapes and growth behavior of surface micro-crack showed very complex and nonlinear propeties and many investigators have performed theoretical analysesand experiments on them to characterize fatigue strength. They had difficulties in estimating fatigue life due to random distribution, growth and coalescence of surface micro-cracks. The straightness of crack growth along intergranular and transgranular was prevented from irregular microstructure and precipitates. Euclid geometry can't quantify shape of surface micro-crack but ftractal geometry can. Therefore, it is suggested that average fractal dimension of surface micro-cracks is able to estimate fatigue life but fractal dimension of maximum surface micro-crack is not in Al 2024-T3 alloy.

• Journal of Educational Research in Mathematics
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• v.12 no.1
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• pp.109-124
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• 2002

This study investigated various effects of WBD(web-based discussion) on mathematical communication, interaction and problem solving in the classroom. We developed a web site including BBS and chat room in order to encourage students' mathematical curiosities and self-studies. The web site had been operated for 6 months. Five classes of 1st grade students were selected from an middle school in Daejon. Moreover, we analyzed several cases for interactional behavior and effect. WBD promote dialogue between a teacher and students. Analysis of feed-back from BBS revealed that student's negative attitudes could be changed to positive ones by step-by-step discussions. Moreover, collaborative learning is enhanced by on-line discussion. But the effects of WBD are affected by the character and ability of a student.

• Journal of Photoscience
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• v.6 no.2
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• pp.61-65
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• 1999

The fluorescence properties and photoisomerization behavior of 1-(9-anthryl)-2-(n-quinolinyl)ethene (n-AQE, n=2-4) have been investigated in various solvents. t-3-AQE is strongly fluorescent, but does not accomplish photoisomerization, similar to parent hydrocarbon compound, t-1-(9-anthryl)-2-phenylethene (t-9-APE) or t-1-(9-anthryl)-2-(1-naphthyl)ethene (t-1-ANE). Fluorescence and photoisomerization oft-2-AQE and t-4-AQE are strongly affected by solvent polarity. Dependence of fluorescence quantum yield on the solvent polarity is moderate for t-2-AQE and large for t-4-AQE. In nonpolar solvent (in n-hexane), they exhibit relatively strong fluorescence, but do not isomerize to cis isomer on irradiation, even if inefficient isomerization is observed for t-4-AQE. However, as solvent polarity increases, their fluorescences become weak with efficient photoisomerization to corresponding cis isomer. Intramolecular charge-transfer excited state is presumed to contribute to photoisomerization. The S$_1$ decay parameters were found to be solvent-dependent due to the charge-transfer character of lowest S$_1$ state. In polar solvents, the activation barrier to twisting is reduced enhancing the isomerization of r-2-AQE and t-4-AQE in the singlet manifold.

• Korean Parent-Child Health Journal
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• v.10 no.2
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• pp.172-181
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• 2007

The purpose of this study was to review the concept, type and factors that affect child rearing attitude of parents and suggest desirable child rearing attitude of parents. Child rearing attitude of parents not only decide the quality of parent-child relationship but also affect child intellectual, emotional, social development and character. Many theorists suggest the type of child rearing attitude of parents, Schaefer's theory is commonly accepted. This model divided into 4 types, affectional-automatic attitude, affectional-controling attitude, rejecting-automatic attitude, rejecting-controling attitude. Through this study, confirmed factors that affect child rearing attitude of parents were family social position, parent's age and educational level, child gender. And other factors were mother has a job or not, marriage satisfaction, number of child and etc. Desirable parent's child rearing attitude were parent's consistency, understanding and acceptance of parents, parent's ideal behavior, democratic attitude of parents, parent's love for their children.

• International Commerce and Information Review
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• v.7 no.3
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• pp.77-94
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• 2005

This paper object is application of electronic Customers Relationship Management(e-CRM) for buyer relationship commitment in korea export firms. So, I'd like to suggest some applications of e-CRM needed to strengthen the export firms in korea. These applications are as follows First, the export companies are required to e-CRM logical architecture that is needs to achievement of buyer relationship commitment. Second, Buyer data source is classify in to three large group by outside data, transaction data and support data. Third, a concept and function of buyer information database. Fourth, e-CRM campaign management for export marketing. Fifth, interaction of buyer and customizing. finally, a point to be considered of korea export companies are national character, data mining out of buyer information database, difference of data gathering and sustaining up date of buyer's new information.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.3 no.2
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• pp.157-160
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• 2003

In this paper, we describe how to represent lower case hand-written English alphabets by a sequence of two to seven fuzzy sets. Each fuzzy set represents an arc segment of the character and each arc segment is assumed to be a part of an ellipse. The part of an ellipse is defined by five quantities; its short and long radii, its orientation angle, whether it is a part of the lower half or the upper half, and whether it is the full half or a part of a half. Hence, we use the Cartesian product of five fuzzy sets to represent each arc segment. We show that this representation is a translation, rotation, and scaling invariant and that it can be used to generate the hand-written English alphabets. The representation we describe is different from the one proposed earlier by the author and when compared with the previous representation, the one described in this paper simulates more closely the behavior of how one writes English characters.

• Journal of Magnetics
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• v.13 no.4
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• pp.132-135
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• 2008

The authors studied the conduction mechanism in an uranium doped low dimensional magnetic system $Ca_2CuO_3$. This system exhibits the S=1/2 quasi 1D antiferromagnetic chains of -Cu-O- with strong magnetic coupling, and demonstrates continuous semiconductor-like behavior with constant covalent insulator character. This paper identifies the conduction is due to thermally activated phonon-assisted electron hopping between dopant uranium sites. The parameter a, the characteristic for hopping probability, was determined to be 0.18 ${\AA}^{-1}$. This value manifests a relatively stronger hopping probability for $Ca_2CuO_3$ as compared with other uranium doped ceramics.

• Advances in materials Research
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• v.8 no.3
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• pp.219-235
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• 2019

This research is devoted to analyzing mechanical-thermal post-buckling behavior of a micro-size beam reinforced with graphene platelets (GPLs) based on geometric imperfection effects. Graphene platelets have three types of dispersion within the structure including uniform-type, linear-type and nonlinear-type. The micro-size beam is considered to be perfect (ideal) or imperfect. Buckling mode shape of the micro-size beam has been assumed as geometric imperfection. Modified couple stress theory has been used for describing scale-dependent character of the beam having micro dimension. Via an analytical procedure, post-buckling path of the micro-size beam has been derived. It will be demonstrated that nonlinear buckling characteristics of the micro-size beam are dependent on geometric imperfection amplitude, thermal loading, graphene distribution and couple stress effects.

• Journal of the Korean Institute of Landscape Architecture
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• v.17 no.1
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• pp.17-27
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• 1989

^x Good Planning, design, and maintenance will be the product of a Process which considers both the nature of man and the nature of nature. Recentry, we emphasize how social and psycological theory, behavioral studios, and community participation may contribute to practical decision making and to the development of appropriate form for human use at all scales of Landscape Architecture. The main purpose of this study was to develop more rational and user oriented theory of urban park planning, design, and maintenance in terms of social - behavioral approach. Study sites were Jungang, Dalsung, Duryu, and Apsan park, where were located Daegu city. In this study, user satisfaction determinants of each park, which were useful for park planning, design and maintenance, were discovered. Privacy and territoriality were examined as an important factors for design a park road examined as an important factors to design a Path and a comfortable space in urban park.

• Advances in nano research
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• v.8 no.2
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• pp.157-167
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• 2020

This paper studies forced vibrational behavior of porous nanocrystalline silicon nanoshells under radial dynamic loads using strain gradient theory (SGT). This type of material contains many pores inside it and also there are nano-size grains which define the material character. The formulation for nanocrystalline nanoshell is provided by first order shell theory and a numerical approach is used in order to solve nanoshell equations. SGT gives a scale factor related to stiffness hardening provided by nano-grains. For more accurate description of size effects due to nano-grains or nano-pore, their surface energy influences have been introduced. Surface energy of inclusion exhibit extraordinary influence on dynamic response of the nanoshell. Also, dynamic response of the nanoshell is affected by the scale of nano-grain and nano-pore.