• Journal of the Korean Society of Earth Science Education
• /
• v.13 no.3
• /
• pp.238-252
• /
• 2020

In this study, we analyzed the types of rebuttals in the argument structure of learning contents in lesson plans constructed by Earth science preservice teachers, and then we explored examples of how they responded to resolving the rebuttal. As a result of analyzing preservice teachers' assignments, discussions, and interviews collected during a total of 20 hours of classes and group discussions for 5 weeks, all 5 types of rebuttals suggested by Verheij (2005) were identified. Through the data analysis, a total of 18 rebuttal cases derived, and these cases were classified into 3 types according to how preservice teachers solve the rebuttals in class. The conclusions and implications based on the results are as follows: First, this study provided empirical data that the thinking process of validating core elements of argumentation and processes of argumentation is actively taking place in preservice teachers' lesson planning using the argument structure, and expanded the scope of application of argumentation in science education research. Second, the argument structure of learning contents should be used to help teachers to come up with strategies to induce students' curiosity and devotion to learn science contents. Third, preservice teachers should have the opportunity to think about the nature of science, including the variability and uncertainty of scientific knowledge when they discover rebuttals and develop solutions to them. Based on these conclusions, implications and suggestions for science education and further research were suggested.

• Proceedings of the KSR Conference
• /
• 2011.10a
• /
• pp.2393-2399
• /
• 2011

In the case where the bottom of railroad is penetrated by non-excavation construction method, the design is performed based on the assumption that there is no displacement and no change of stress However, measurement data showed that reduction of earth pressure and relaxation of stress take place by the displacement. In this study, we investigated the earth pressure on the structure under the railroad constructed by a non-excavation method and the stress relaxation region. The design based on earth pressure is non-economical because it is an over design. Relaxation of stress may lead to road base settlement and rail irregularly due to the reduced railroad supporting stiffness, to ballast crack in the case of concrete roadbed. The result showed that it is reasonable to set the stress on the structures as active earth pressure not as earth pressure at rest. Additionally, the study on the stress relaxation region identified the regions that should be supported in future construction by a non-excavation method.

• Journal of Ocean Engineering and Technology
• /
• v.15 no.4
• /
• pp.92-100
• /
• 2001

It is very important to determine the coefficient of earth pressure at rest accurately in order to estimate the behavior of soil structure. For estimation of K/sub 0/-value depending upon the stress history of dry sand, a new type of K/sub 0/-oedeometer apparatus is devised, and the horizontal earth pressure is accurately measured. For this study, 2 types of one-cyclic K/sub 0/-Loading/unloading models have been studied experimentally using four relative densities of the sand. The results obtained in this test are as follows : K/sub on'/ the coefficient of earth pressure at - rest for virgin loading is a function of the angle of internal friction Φ' of the sand and is determined as K/sub on/=1 - 0.914 sin Φ', K/sub ou'/ the coefficient of earth pressure at rest for virgin unloading is a function of K/sub on/ and over consolidation ratio(OCR), and is determined as K/sub ou/=K/sub on/(OCR)K/sup a/. The exponent α, increases as the relative density increases. K/sub or'/ the coefficient of earth pressure at rest for virgin reloading decreases in hyperbola type as the vertical stress, σ/sub v/’, increases. And, the stress path at virgin reloading leads to the maximum prestress point, independent upon the value of the minimum unloading stress. The gradient of this curve, m/sub r/ increases as OCR increases.

• Journal of the Korean Magnetics Society
• /
• v.22 no.5
• /
• pp.188-193
• /
• 2012

Permanent magnet is one of the most important parts in modern industry and the rare earth elements play an essential role for operation of permanent magnet. As is well known, the rare earth elements are mostly produced in China and the world is now facing serious problems owing to supply and demand imbalances. Many attempts have been performed to replace these rare-earth based permanent magnets by rare-earth free magnets, but they have not been successful so far. Regarding this issue, we discuss about an exchange spring magnet as a potential rare earth free permanent magnet structure.

• Journal of the Korean earth science society
• /
• v.30 no.1
• /
• pp.96-110
• /
• 2009

The ESE (Earth Systems Education) teaching module was developed to teach an "Earth and Star" unit for the 8th grade (aged 14) students. The planet remodeling activity was developed as a sub-ESE teaching module. The main point of this activity was that students were supposed to remodel planets for life to live on. The purpose of this study was to visualize students' thought and to interpret their understandings through their drawings and writings. A framework of analysis with four categories was designed and applied to analyze students' cognitive structure. In order to explore students' cognitive contents, the analyzing factors were classified into two domains: subsystems of the earth systems and use of science & technology. Results revealed via the planet remodeling activity that students' cognitive characteristics were impacted by ESE activities such as Earth literacy.

• Atmosphere
• /
• v.22 no.2
• /
• pp.259-265
• /
• 2012

This study investigates the reason why the barotropic vorticity structure prevails vertically in response to the enhanced convection associated with the boreal summer intraseasonal oscillation over the central Indian Ocean. The relative vorticity tendency analysis for a 2.5-layer simplified model demonstrates that the barotopic vorticity structure is predominant due to the following two factors: 1) vertical easterly shear on the meridional gradient of barotropic divergence (which induces generation of barotropic vorticity twice larger than that of baroclinic vorticity); and 2) vertical easterly shear on the meridional gradient of baroclinic divergence (which appears only in relation to the generation of barotropic vorticity). The percentage of contribution by each term to barotropic and baroclinic vorticity tendency equations is presented.

• Journal of the Korean earth science society
• /
• v.30 no.5
• /
• pp.550-564
• /
• 2009

When magnetotelluric (MT) data are obtained in the vicinity of the coast, the surrounding seas make it difficult to interpret subsurface structure, especially the deep part of the subsurface. We introduce an iterative method to correct the sea effect, based on the previous topographic correction method that removes the distortion due to topographic changes in seafloor MT data. The method first corrects the sea effect in observed MT impedance, and then inverts corrected response in a model space without the sea. Due to mutual coupling between the sea and the subsurface structure, the correction and inversion steps are iterated until the changes in each result become negligible. The method is tested for 1- and 2-D structures using synthetic MT data produced by 3-D forward modeling including surrounding seas. In all cases, the method closely recovers the true structure assumed to generate synthetic responses after a few iterations.

• Journal of the Korean Society for Heat Treatment
• /
• v.13 no.4
• /
• pp.217-223
• /
• 2000

The boronizing effects of STD 61 steel have been studied on the micro structure and hardness. The STD 61 Steel was soaked in molten salt, consisted of KCl, $BaCl_2$, NaF, $B_2O_3$, FeB, and Ce, at various temperatures and times. The boronizing conditions for the peak hardness were the temperature range of $900^{\circ}C$ to $950^{\circ}C$ for 5 hr and that of $1000^{\circ}C$ for 3 hr, respectively. Four boride layers such as FeB, $Fe_2B$, ${\alpha}$ and matrix layer surface were observed from the microscopic surface examination. The thickness of boride layer was increased by increasing the boronizing time and the temperature. The structure of boride layer was tooth shape.

• International Journal of Aeronautical and Space Sciences
• /
• v.11 no.1
• /
• pp.26-30
• /
• 2010

The present paper studies the thermally-induced vibration phenomenon of the flexible space boom structure. In order to simulate the thermally-induced vibration phenomenon of the flexible thin boom structure of the spacecraft with the attached tip mass in space, the thermally-induced vibration including thermal flutter is experimentally investigated at various thermal environments using a heating lamp in vacuum chamber. In this experimental study, fluctuating characteristics, natural frequency and thermal strains of the thermally-induced vibration are parametrically investigated at various thermal environment conditions. Finally the thermally-induced vibration of the flexible boom structure of the orbiting earth satellite in solar radiation environment from the earth eclipse region including umbra and penumbra is simulated using the power control of the heating lamp in the vacuum chamber.

• Applied Microscopy
• /
• v.32 no.3
• /
• pp.185-193
• /
• 2002

The works of texture electron diffraction patterns for crystal structure analysis are written in Russian or introduced briefly in books written in English, which makes it difficult to be understood. In addition to working out the equations, vector theory corrects some errors included in the established formulas for texture electron diffraction patterns.