• Structural Engineering and Mechanics
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• v.8 no.6
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• pp.623-637
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• 1999

This paper presents a four-noded quadrilateral $C^0$ strain plate element for the analysis of thick laminated composite plates. The element formulation is based on: 1) the third-order shear deformation theory; 2) assumed strain element formulation; and 3) interrelated edge displacements and rotations along element boundaries. Unlike the existing displacement-type composite plate elements based on the third-order theory, which rely on the $C^1$-continuity formulation, the present plate element is of $C^0$-continuity, and its element stiffness matrix is evaluated explicitly. Because of the third-order expansion of the in-plane displacements through the thickness, the resulting theory and hence elements do not need shear correction factors. The explicit element stiffness matrix makes the present element more computationally efficient than the composite plate elements using numerical integration for the analysis of thick layered composite plates.

• Korean Journal of Remote Sensing
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• v.36 no.5_1
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• pp.707-723
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• 2020

In this study, a decision tree type of quality control (QC) method was developed to improve the temporal-spatial representation and accuracy of the visibility data being operated by the Korea Meteorological Administration (KMA). The quality of the developed QC method was evaluated through the application to the 3 years (2016.03-2019.02) of 290 stations visibility data. For qualitative and quantitative verification of the developed QC method, visibility and naked-eye data provided by the KMA and QC method of the Norwegian Meteorological Institute (NMI) were used. Firstly, if the sum of missing and abnormal data exceeds 10% of the total data, the corresponding point was removed. In the 2nd step, a temporal continuity test was performed under the assumption that the visibility changes continuously in time. In this process, the threshold was dynamically set considering the different temporal variability depending on the visibility. In the 3rd step, the spatial continuity test was performed under the assumption of spatial continuity for visibility. Finally, the 10-minute visibility data was calculated using weighted average method, considering that the accuracy of the visibility meter was inversely proportional to the visibility. As results, about 10% of the data were removed in the first step due to the large temporal-spatial variability of visibility. In addition, because the spatial variability was significant, especially around the fog area, the 3rd step was not applied. Through the quantitative verification results, it suggested that the QC method developed in this study can be used as a QC tool for visibility data.

• Journal of The Korean Association For Science Education
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• v.17 no.1
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• pp.21-29
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• 1997

Many middle school students have difficulty in understanding biological concepts because too many concepts are presented in the textbook compared to limited school hours. So, it is necessary to select concepts which are indispensable. The purpose of this study is to select key concepts in the unit 'The Continuity of Life' by surveying students' and teachers' cognition on the concepts. In this study, 78 concepts were extracted from 'Science 3', unit II 'The Continuity of Life'. To survey how students and teachers think the concepts, Likert type questionnaires were made. 300 third grade middle school students and 34 biology teachers were selected by random sampling and the questionnaires were applied. The following results were obtained:1. Students thought 59 concepts out of 78 were important and the mean score of important level of the concepts was 3.60. Students thought 26 concepts out of 78 were difficult and the mean score of diffculty level'of the concepts was 3.26. The more they think the concepts important, the more they think them difficult (r=0.7462, p<0.001). 2. Teachers thought 55 concepts out of 78 were important and the mean score of important level of the concepts was 3.82. Teachers thought 33 concepts out of 78 were difficult and the mean score of diffculty level of the concepts was 3.31. The more they think the concepts important, the more they think them difficult (r=0.6138, p<0.001). 3. The selected concepts were considered more important by teachers than by students(t=2.0150, p<0.05). However, there was no significant difference in evaluating the difficulty level of the concepts(t=0.7327, p>0.05). 4. It was found that students have difficulty in understanding concepts when they are presented in the textbook to require formal preparation than concrete preperation(t=2.6612, p<0.05).

• Journal of the Computational Structural Engineering Institute of Korea
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• v.31 no.5
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• pp.275-282
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• 2018

Using isogeometric analysis(IGA) gives more accurate results for higher order mode in eigenvalue problem than using the finite element method(FEM). This is because the FEM has $C^0$ continuity between elements, whereas IGA guarantee $C^{P-1}$ between elements for p-th order basis functions. In this paper, a mode based reduced model is constructed by using IGA and dynamic behavior analysis is performed using this advantage. Craig-Bampton(CB) method is applied to construct the reduced model. Several numerical examples were performed to compare the eigenvalue analysis results for various order of element basis function by applying the IGA and FEM to simple rod analysis. We have confirmed that numerical error increases in the higher order mode as the continuity between elements decreases in the IGA by allowing internal knots multiplicity. The accuracy of the solution can be improved by using the IGA with high inter-element continuity when high-frequency external force acts on the reduced model for dynamic behavior analysis.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.15 no.1
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• pp.119-132
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• 2012

In order to connect eco-corridor and to harmonize with natural environment, it is necessary to construct small debris barrier. Therefore, we will evaluate applicability of small debris barrier which made of tetrapod utilized in construction of seashore protection facilities and breakwater. From result compared with the adaptation processes in fields, tetrapod were stabilized to critical tractive force. Stability evaluation method on sliding and overturn of tetrapod debris barrier was developed, and hereafter could be applied to similar debris barriers. According to results analyzed to continuity on sediment supply in debris barrier, boulders were deposited in upstream and gravels were deposited in downstream. Therefore, tetrapod debris barrier will be able to prevent in the long-term the erosion of river bed in down-stream, and the maintenance is easy because dredging is not necessary. Current were formed in between the tetrapod provided eco-corridors for fishes and shellfishes.

• Journal of The Korean Association For Science Education
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• v.15 no.2
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• pp.233-240
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• 1995

The purpose of the study is to certify the validity and effectiveness of the learning hierarchy and to define the effective teaching order in life continuity. To achieve this purpose, two experimental groups which were instructed varying the sequence of the instructional units. Teaching order based on the learning hierarchy was given to experimental group and descriptive order of current text was given to control group. The findings of the study are as follows: 1. Learning Hierarchy before learning had differ with order of the textbook, but hierarchy of both group has showed similar to the sequence of textbook, after learning. 2. The effect of learning hierarchy represented no significant different between control and experimental group.

• Bulletin of the Korean Mathematical Society
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• v.30 no.1
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• pp.109-115
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• 1993

In 1940 Eidelheit showed that every homomorphism of a Banach algebra onto the Banach algebra B(X) of all bounded linear operators on a Banach space X is continuous. At about the same time, Gelfand proved that every homomorphism of a commutative Banach algebra into a commutative semi-simple Banach algebra is continuous. In [7] Johnson proved that every homomorphism of a Banach algebra onto non-commutative semi-simple Banach algebra is continuous, and this is still the most important result of this type. In this paper we are concerned with continuity of derivations on commutative Banach algebras and of homomorphisms into commutative Banach algebras. Throughout this paper we suppose that A is a commutative Banach algebra. R will denote the redical of A.

• Communications of the Korean Mathematical Society
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• v.37 no.1
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• pp.163-176
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• 2022

In this paper, we introduce some new classes of generalized mappings and prove some common fixed point theorems for a pair of asymptotically regular mappings. Our results extend and improve various well-known results due to Kannan, Reich, Wong, Hardy and Rogers, Ćirić, Jungck, Górnicki and many others. In addition to it, a sequential fixed point for a mapping which is the point-wise limit of a sequence of functions satisfying Ćirić-Proinov-Górnicki type mapping has been proved. Supporting examples have been given in strengthening hypotheses of our established theorems.

• East Asian mathematical journal
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• v.16 no.1
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• pp.161-168
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• 2000

The purpose of this paper is to introduce a new type of weakend fuzzy continuity called fuzzy almost precontinuous and investigate properties of it.

• Journal of the Chungcheong Mathematical Society
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• v.10 no.1
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• pp.23-28
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• 1997

In this paper, we investigate continuity of $$F(x)=(H){\int}_a^x\;fdG$$ and Henstock-Stieltjes integrability of product of two functions and obtain the formula of integration by parts for the Henstock-Stieltjes integral.