• 대한수학교육학회지:수학교육학연구
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• 제8권2호
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• pp.553-563
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• 1998

In this thesis, I examined Bruner's EIS theory from the viewpoint of epistemology based on Piaget's genetic epistemology. Although Bruner's ideal thought which insisted ‘to teach the structure’accepted Piaget's theory in the methodology of realization, it is different from Piaget in understanding knowledge. The difference is shown from understanding the meaning of ‘structure’. Piaget's concept of structure is something that has overcome the realistic viewpoint of the traditional epistemology and is reconstructed through endless self-regulative transformational process. However Bruner's is used as a realistic meaning as we can see in the Plato's recollection theory. Therefore Piaget's ‘stage of development’means the difference of structure which lies in the generative process and it includes the qualitive difference of level. On the other hand, Bruner, who is trying to translate and suggest the fixed structure to the children understood Piaget's stage of development as the difference in the ways of representation. Piaget's operational constructivism insists that the children should ‘construct’the knowledge through their activity, and especially in case of the lohico-mathematical recognition, the source should be internalized activity, that is, operation. In view of this assertion, Burner's idea which insists to accept the structure of knowledge as a fixed reality and to suggest the translated representation proper to the cognitive structure of the children to teach them, has a danger of emphasizing only the functional aspects to deliver the given knowledge ‘quickly’. And it also has the danger of damaging ‘the nature of the knowledge’in the translated knowledge.

• 지식경영연구
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• 제16권2호
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• pp.47-66
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• 2015

Due to multiple information sources, external information search(EIS) is the key issue on smart tourism environments. EIS is more important on experiential goods such as exhibition and convention. Despite the increasing importance of EIS, very little is known about what is the more effective information source in this area. In this paper, we attempt to examine the relations of satisfaction and between both online and offline information. This research analyzes an empirical model including EIS, affective involvement, perceived usefulness, satisfaction to student visitors on exhibition experience. Hence, six hypotheses are developed to test the relations of EIS and satisfaction using the mediating effects of affective involvement. Specifically, we developed a research model by employing the Uses and Gratification(U&G) framework and tested it to understand how student visitors' involvement and satisfaction might be changed according to EIS. Survey data was collected from 203 student visitors on "2014 Expo KCCE" was used to test the model using structural equation modeling. The implications of our empirical findings for both research and practice are discussed.

• 한국정보시스템학회지:정보시스템연구
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• 제6권1호
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• pp.257-291
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• 1997

Today, executives in the company operate their organizations under highly competitive environments with dynamic technological, economic, and political changes. Under these new environment changes, they play the important role in establishing the future directions and strategic orientations of organizations. In general, executive information systems (EIS) are designed to support these roles of executives. They can help executives access and use the information they require about the organization's internal and external environments. In spite of such potential EIS support for executives, only a limited number of empirical studies have been published in this area. by employing a well-established theory of computer usage behavior (Technology Acceptance Model : TAM), this study systematically investigates the key factors in the successful utilization of an EIS. The empirical results from this study may prove useful for both IS researchers and practitioners.

• Corrosion Science and Technology
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• 제18권5호
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• pp.155-167
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• 2019

In this study, two novel Schiff base compounds including (3-(4-Chlorophenyl isoxazole-5-yl) methanol and (3-(2,4 dichlorophenol isoxazole-5-yl) methanol as corrosion inhibitors for mild steel in 1 M hydrochloric acid solution were investigated by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and density functional theory (DFT) computations. The results showed that the corrosion inhibition efficiency (IE) is remarkably enhanced with the growing concentration of the Schiff base inhibitors. The results from Tafel polarization and EIS methods showed that IE decreases with gradual increments of temperature. This process can be attributed to the displacement of the adsorption/desorption balance and hence to the diminution of the level of a surface coating. Also, the adsorption of two inhibitors over mild steel followed the Langmuir adsorption isotherm. Too, the results of the scanning electron microscope (SEM) images showed that the Schiff base inhibitors form an excellent protective film over mild steel and verified the results by electrochemical techniques. Additionally, the results from the experimental and those from DFT computations are in excellent accordance.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 추계 학술발표회 제17권2호
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• pp.659-662
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• 2005

Electrochemical impedance spectroscopy (EIS) has been extensively used to try to evaluate the corrosion state of the steel/concrete system. This technique is attractive because, in theory, used in a wide range of frequencies, it can give detailed information about the mechanisms and kinetics of the electrochemical reactions. Impedance measurements were performed using potential control and measuring the corresponding current response. One-year-old southern exposure test. specimens were used in the current study. The effectiveness of corrosion inhibiting additives was evaluated. The corrosion current densities estimated by impedance measurements were confirmed by those determined using linear polarization techniques. The purpose of this study was to evaluate the long-term-performance potential of the corrosion inhibitors in chloride contaminated reinforce concrete.

• 한국수학교육학회지시리즈E:수학교육논문집
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• 제29권2호
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• pp.215-239
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• 2015

본 연구는 다양한 표상활동을 중심으로 한 분수학습이 분수의 이해 및 수학적 태도에 미치는 영향을 알아보기 위한 것으로서 서울 소재 B초등학교 4학년 33명 전체학생을 대상으로 실시하였다. 활동적, 영상적, 상징적 표상활동으로 이루어진 분수학습을 6주간 15차시에 걸쳐 진행한 결과 관계적 이해에 도달한 학생들의 비율이 증가하였으며, 분수 학업성취도 검사 I, II, III에서 평균 90점 가까이 또는 그 이상의 높은 성취도를 보였다. 수학적 태도 변화를 알아보기 위해서 두 종속표본 t검정을 실시한 결과, 유의수준 .01에서 통계적으로 유의미한 차이가 있는 것으로 나타났다. 결론적으로 다양한 표상활동 중심의 분수학습은 학생들의 관계적 이해도와 분수 이해력을 향상시키고, 학생들의 학습지향성, 자기통제, 흥미, 가치인식, 자신감을 높이며, 불안감을 감소시키는 등의 수학적 태도면에서도 긍정적 영향을 미쳤다고 할 수 있다.

• 대한수학교육학회지:학교수학
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• 제3권2호
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• pp.355-372
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• 2001

The primary school mathematics emphasizes some activities such as visualizing figures, drawing figures and comparing figures from various angles. These activities could be undertaken throughout examination, experiments and exploration of the substantial materials. They could also be undertaken by using the objects found in a daily life informally. The 7th curriculum of mathematics reflects this trend and includes the systematized activities in teaching spatial sense in geometry. However, it still requires more researches on the teaching methodology of spatial sense and the conceptual analysis of spatial sense. In this study, the concept of spatial sense is analyzed and Mackim's 3-levels teaching methodology and Bruner's EIS theory and suggestions are reviewed as a possible teaching methodology of spatial tasks. As a conclusion, this study suggests a teaching-learning methodology of spatial tasks at the levels of 2-GA and 3-Ga of the 7th curriculum of mathematics.

• Journal of Electrochemical Science and Technology
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• 제6권1호
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• pp.7-15
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• 2015

3-(4-Iodophenyl)-2-imino-2,3-dihydrobenzo[d]oxazol-5-yl 4-methylbenzenesulfonate (4-IPhOXTs) was synthesized and its inhibiting action on the corrosion of stainless steel 316L (SS) in sulfuric acid was investigated by means of potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results of the investigation show that this compound has excellent inhibiting properties for SS corrosion in sulfuric acid. Inhibition efficiency increases with increase in the concentration of the inhibitor. The adsorption of 4-IPhOXTs onto the SS surface followed the Langmuir adsorption model with the free energy of adsorption ΔG⁰_ads of −8.45 kJ mol⁻¹ . Quantum chemical calculations were employed to give further insight into the mechanism of inhibition action of 4-IPhOXTs.

• Corrosion Science and Technology
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• 제21권1호
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• pp.21-31
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• 2022

Potentiodynamic polarization, EIS measurements, quantum chemical calculations, and molecular dynamic simulations were used to investigate the corrosion behavior of mild steel in 0.5 M aqueous hydrochloric acid medium in the presence or absence of nystatin drug. Potentiodynamic tests suggested that this molecule could act as a mixed inhibitor due to its adsorption on the mild steel surface. The objective of this study was to exploit theoretical calculations to gain a better understanding mechanism of inhibition. Calculating the adsorption behavior of the investigated molecule on Fe (1 1 0) surface was accomplished using Monte Carlo simulation. Molecules were also investigated using Density Functional Theory (DFT), specifically PBE functional, in order to identify the link between molecular structure and corrosion inhibition behavior of the compound under investigation. Adsorption energies between nystatin and iron were estimated more accurately by utilizing Molecular Mechanics calculation with Periodic Boundary Conditions (PBC). Estimated theoretical parameters significantly assisted our understanding of the corrosion inhibition mechanism exhibited by this molecule. They were found to be in accord with experimental results.

• Journal of Electrochemical Science and Technology
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• 제8권1호
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• pp.43-52
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• 2017

In this paper, for the first time, the electroanalytical study of Triethylenediamine, TEDA was done on a typically graphene modified carbon paste electrode (Gr/CPE) in pH=10.5 of phosphate buffer solutions (PBS). The surface morphology of the bare and modified electrodes was characterized by scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The electro-oxidation of TEDA was investigated at the surface of modified electrode. The results revealed that the oxidation peak current of TEDA at the surface of Gr/CPE is 2.70 times than that shown at bare-CPE. A linear calibration plot was observed in the range of 1.0 to 202.0 ppm. In this way, the detection limit was found to be 0.18 ppm. The method was then successfully applied to determination of TEDA in aqueous samples obtained from two kinds of activated carbon from the masks of war. On the other hand, density functional theory (DFT) method at B3LYP/6-311++G** level of theory and a conductor-like Polarizable Continuum Model (CPCM) was used to calculate the $pK_a$ values of TEDA. The energies of lowest unoccupied molecular orbital ($E_{LUMO}$) and highest occupied molecular orbital ($E_{HOMO}$), gap energy (${\Delta}E$) and some thermodynamic parameters such as Gibbs free energy of TEDA and its conjugate acid ($HT^+$) were calculated. The results of calculated $pK_a$ were found to be in good agreement with the experimental values.