• Journal of the Korean Chemical Society
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• v.62 no.3
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• pp.243-252
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• 2018

In this study, we compared 8th graders' macroscopic and microscopic conceptions related to the properties of substances. A test for the basic particle concept and a test for the macroscopic and microscopic concepts of melting point, solubility, and density were developed and administered to 371 students. Their responses were classified into 4 categories on the bases of their understanding of the macroscopic and microscopic concepts. The proportions and characteristics of each category were also analyzed. The analyses of the results revealed that the students who understood the macroscopic concepts had various misconceptions at the microscopic level. Many students had difficulty in understanding not only microscopic concepts but macroscopic concepts. The microscopic responses of the students who did not understand the macroscopic concepts hardly corresponded with their macroscopic level responses. The students who responded correctly to the test for the basic particle concept also had difficulty in understanding the concept of the properties of substances. When they understood the macroscopic concepts, the proportions of the students who understood the microscopic concepts were high. On the bases of the results, educational implications for effective teaching and learning of concepts related to the properties of substances and for improving the future national curricular are discussed.

• Journal of Educational Research in Mathematics
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• v.11 no.1
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• pp.1-10
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• 2001

Most existing research into the metacognitive approach in mathematics learning has been concentrated mainly in the study of phenomena of metacognitive (including the affective) behaviour in the context of mathematical problem solving or more broadly mathematical content-elated learning. However, this study originally constructs the concept of "macroscopic metacognition" which could be differentiated with general metacognition, and draws out macroscopic-metacognitive factors among the elementary and middle school students through individual interview. Questionnaire research is executed to find out how the macroscopic metacognition is included into the students' mathematics learning and the relationship between their mathematics learning accomplishment and macroscopic metacognition. Thus, a considerable degree of the positive relationship between these two variables was found out.

• Korean Journal of Crystallography
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• v.11 no.3
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• pp.157-161
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• 2000

In a 200nm Cz-Si crystal, a macroscopic fluctuation in pulling rate was intentionally introduced an then the variations of the pulling rate and the position of OSF-ring were compared each other. The formation behavior of OSF-ring in the effective volume, defined as the region between the growth interface position -α and the growth interface position +α, is most affected by the pulling rate fluctuation. To understand the correct effect of a macroscopic pulling rate fluctuation, its cumulative effect in the effective volume should be considered. A new concept of modeling for it was proposed here.

• The Journal of the Convergence on Culture Technology
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• v.7 no.3
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• pp.303-310
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• 2021

A method for developing a visual information concept that analogously compares and analyzes macroscopic data changes in a simple form is needed. The development of the visual information concept requires the selection of visualization form, selection of rhetorical effects, and selection of digital expression elements. Among them, an example of a rhetorical effect selection method for effectively delivering visual information to a user is presented. In this study, metaphorical rhetoric, which allows data comparison and analysis from a macroscopic point of view, was selected for stock price analysis by period and industry. We present a two-dimensional three-stage shape change using a dandelion with spreading cockle hair as a metaphor and a three-dimensional three-stage shape change information expression method using a coral peony flower that changes shape and color according to time as a metaphor. Using this rhetorical metaphor, it is possible to compare macroscopic trading changes and stock prices by industry.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.11
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• pp.4483-4501
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• 2020

Recent findings identified the scatter and shape of MFD (macroscopic fundamental diagram) is heavily influenced by the spatial distribution of link density in a road network. This implies that the concept of MFD can be utilized to divide a heterogeneous road network with different degrees of congestion into multiple homogeneous subnetworks. Considering the actual traffic data is usually incomplete and inaccurate while most traffic partition algorithms rely on the completeness of the data, we proposed a three-step partitioned algorithm called Iso-MB (Isoperimetric algorithm - Merging - Boundary adjustment) permitting of incompletely input data in this paper. The proposed algorithm was implemented and verified in a simulated urban transportation network. The existence of well-defined MFD in each subnetwork was revealed and discussed and the selection of stop parameter in the isoperimetric algorithm was explained and dissected. The effectiveness of the approach to the missing input data was also demonstrated and elaborated.

• Journal of The Korean Association For Science Education
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• v.25 no.7
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• pp.773-786
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• 2005

This study investigated high school student and chemistry teacher perceptions on the effect of water vapor in the air on evaporation and boiling of water by a questionnaire. In science textbooks evaporation and the boiling of water are related to the vaporization concept, boiling is related to vapor pressure and air pressure, and vapor pressure is related to the vapor concept in the air. High school student and chemistry teacher perceptions on these linkages were compared. Science textbooks were also analyzed for reasons behind these diverse perceptions. Results revealed that a majority of students conceptualized that vapor in the air was related to evaporation and boiling, but were unable to distinguish the evaporation phenomena at the macroscopic level and the evaporation of water molecules at the microscopic level. They also thought that vapor in the air affected vapor pressure and boiling. Although the percentage of teacher scientific conception was higher, a great number of teachers had diverse perceptions on evaporation and boiling just as students had. Common explanations of evaporation and boiling phenomena in science textbooks were at the macroscopic level. Moreover, there were few connections of concepts even if the explanations were at the microscopic level.

• Structural Engineering and Mechanics
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• v.16 no.4
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• pp.371-390
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• 2003

The concept of the seismic slit shear wall was proposed in the early 1990's. A series of experimental and theoretic studies on the wall with reinforced concrete short connecting beams cast in the slit were carried out. In this paper another type of slit shear wall is studied. It is one with vertical slit purposely cast within the wall, and the rubber belt penetrated by a part of web shear reinforcement as seismic energy-dissipation device is filled in the slit. Firstly, an experiment under cyclic loading was carried out on two shear wall models, one slit and the other solid. The failure mechanism and energy-dissipation capacity are compared between the two different models, which testifies the seismic performance of the slit wall improved significantly. Secondly, for engineering practice purpose, a macroscopic analytical model is developed to predict the nonlinear behavior of the slit shear wall under cyclic loading. The mechanical properties of each constituent elements of this model are based on the actual behavior of the materials. Furthermore, the effects of both the axial force and bending moment on the shear behavior are taken into account with the aid of the modified compression-field theory. The numerical results are verified to be in close agreement with the experimental measurements.

• Journal of the Korean Society of Safety
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• v.33 no.4
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• pp.98-104
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• 2018

Macroscopic accident analyses have been conducted to incorporate transportation safety into long-term transportation planning. In macro-level accident prediction model, exposure variable(e.g. a settled population) have been used as fundamental explanatory variable under the concept that each trip will be subjected to a probable risk of accident. However, a settled population may be embedded error by exclusion of active population concept. The objective of this research study is to develop macro-level accident prediction model using floating population variable(concept of including a settled population and active population) collected from mobile phone data. The concept of accident prediction models is introduced utilizing exposure variable as explanatory variable in a generalized linear regression with assumption of a negative binomial error structure. The goodness of fit of model using floating population variable is compared with that of the each models using population and the number of household variables. Also, log transformation models are additionally developed to improve the goodness of fit. The results show that the log transformation model using floating population variable is useful for capturing the relationships between accident and exposure variable and generally perform better than the models using other existing exposure variables. The developed model using floating population variable can be used to guide transportation safety policy decision makers to allocate resources more efficiently for the regions(or zones) with higher risk and improve urban transportation safety in transportation planning step.

• Journal of Mechanical Science and Technology
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• v.15 no.12
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• pp.1699-1710
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• 2001

The characteristics of methanol and methanol blended (M85) sprays were investigated under atmospheric conditions at various temperature, ranging from on-vaporizing to vaporizing ambient conditions (298∼353 K). From laser scattering images, the macroscopic characteristics of the spray, such as the spray tip penetration and the spray angle, were determined. Entropy concept was introduced to represent homogeneity and PIV analysis was adopted to determine the fluid dynamic information at each location of the spray. The correlation between entropy and vorticity strength enabled us to find their relations. The effect of ambient composition, mainly of viscous effect as affected by CO$_2$levels, was investigated using PIV and entropy analysis. Spray width and entropy value were found to tend to decrease at increased CO$_2$levels.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.6
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• pp.44-50
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• 2002

The spray characteristics of GDI(Gasoline Direct Injection) injector affects on engine efficiency and emission of a GDI engine. Thus, many researchers have investigated the spray characteristics and the mixture formation of GDI injector. In this study, it was tried to provide the fundamental data for GDl injector design which effects on the spray macroscopic characteristics such as penetration and spray angle. In addition, the mixture formation analyzed by using entropy analysis. The entropy analysis is based on the concept of statistical entropy, and it identifies the degree of homogeneity in the fuel concentration. The results show that as injection pressure increases but as ambient pressure increases, spray penetration decreases and spray angle doesn't affected by increasing injection pressure and ambient temperature. From the entropy analysis results, we could find that the direct diffusion phenomena is a dominant factor in the formation of a homogeneous mixture at downstream of GDI spray especially in vaporizing conditions.