• Research in Mathematical Education
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• v.14 no.3
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• pp.263-279
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• 2010

Teachers' personal knowledge (PK) is an element in their pedagogic-practical knowledge. This study exposes the PK of primary school mathematics teachers regarding solid geometry through reflection. Students are exposed to solid geometry on various levels, from kindergarten age and above. Previous studies attested to the fact that students encounter difficulties-strong dislike and fear engendered by geometry. A good number of teachers have strong dislike to solid geometry, as well. Therefore, those engaged in teaching the subject must address the problem and try to overcome these difficulties. In this paper we have introduced the reflective process among teachers in primary school, including application of Van-Hiele's theory to solid geometry.

• Education of Primary School Mathematics
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• v.15 no.2
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• pp.147-158
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• 2012

In this paper we introduced the reflection cluster problems. They are not well known in Korea education field. We used two reflection cluster problems and analysed the responses of the gifted students. Finally, we asked how they felt about reflection cluster problems. The results of this paper will help to make new assessment items and develop new programs for the gifted education.

• Education of Primary School Mathematics
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• v.5 no.1
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• pp.1-11
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• 2001

The purpose of the study is to introduce how tessellation can be used and integrated to connect geometry to pattern in elementary mathematics educations. Tessellation examples include transformations such as translational symmetry, rotational symmetry, reflection symmetry, and glide reflection symmetry. In addition, many examples of tessellation using softwares such as Escher, TesselMania!, and LOGO programs. Further, future study will continue to foster students and teachers to try to construct their alive mathematics knowledge. The study of geometry and patterns require a rich teaching and learning environment provided by in-depth understanding of thinking connections to objects in real world.

• Journal of the Korean Geophysical Society
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• v.2 no.4
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• pp.241-250
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• 1999

Reflection coefficients of the seafloor have been calculated from the amplitude ratio of secondary to primary water bottom reflection in seismic data obtained from Bransfield Strait, Antarctic Peninsula. Test processing for the coefficients shows that moving average is effective to reduce severe fluctuation of the coefficient measured at each point. Relationship between the coefficients and the properties of water bottom is analyzed to illuminate geological environment. In the central Bransfield Basin, the magnitude of reflection coefficients decreases as it is distant from the sedimentary sources. Reflection coefficients range from 0.12 to 0.2 near the continental slope of the basin, and from 0.1 to 0.12 in the basin floor. In the western Bransfield basin, reflection coefficients between 0.2 to 0.3 are obtained from the area eroded by glacial movement. On the volcanic structures near Deception Island, the coefficients show relatively high values more than 0.2. Paleo-geological structures uplifted by tectonic movement and outcropped by glacial erosion have relatively high coefficients.

• Journal of Institute of Control, Robotics and Systems
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• v.2 no.4
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• pp.324-329
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• 1996

In this paper, we present a vision algorithm to extract the tire information markings on the sidewall of tires. Since the appearance of tire marks is the same as its background, a primary feature to distinguish tire marks from their background is the roughness. Generally, the roughness of tire marks is different from that of its bakground: the surface of tire marks is smoother than the backgrounds. Light incident on the tire surface is reflected differently according to the roughness. For smoother surfaces, the surface irradiance is much stronger than that of rough surfaces. Based on these phenomena and observation, we propose an optimal illumination condition based on Torrance-Sparrow reflection model. We also develop an efficient reflectance-ratio based operator to extract the boundary of tire marks. Even with a very simple masking operation, we were able to obtain remarkable boundary extraction results from real experiments using many tires. By explicitly using the surface reflection model to explain the intensity variation on the black tire surface, we demonstrate that a physics-based vision method is powerful and feasible in extracting surface markings on tires.

• Journal of Korean Elementary Science Education
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• v.18 no.1
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• pp.53-63
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• 1999

This research surveyed how much the professors ill tile university of education and primary school teachers understand the 6th National primary science Curriculum. Items to check tile degree of purpose description, reflection of basic policy, appropriateness of content, its organization, teaching method and evaluation, its influence on textbook and putting in practice of themselves were evaluated neutral or positive by most of them. But the opinion of responders were divided into tile two extremes, positive or negative, ell tile possibility of carrying out various inquiry activities and participation in science activities of students. Both of professors and teachers indicated that tile explanatory book of curriculum and annotated teachers' edition are the principal sources of information about curriculum. And the teachers stated that the shortage of information and materials are the principal factors to obstruct the change of lessons according to new curriculum.

• Geophysics and Geophysical Exploration
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• v.21 no.1
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• pp.41-53
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• 2018

In the traditional seismic processing, multiple reflections are treated as noise and therefore they are eliminated during data processing. Recently, however, many studies have begun to consider multiples as signals rather than noise for seismic imaging. Multiple reflections can illuminate an area where primary reflections are not able to cover, thus it is allowed that a smaller number of shots and receivers are used for imaging large areas. In order to verify this, surface-related multiples were used for reverse-time migration (RTM), and then we compared the results with conventional RTM images which are generated from primary reflections. To utilize multiples, we separated multiples from whole seismic data using surface-related multiple elimination (SRME) method. Numerical examples confirmed that the migration using multiples can image wider area than the conventional migration, particularly in the shallow subsurface layers. In addition, the migration of multiples could eliminate the acquisition footprints.

• Education of Primary School Mathematics
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• v.18 no.2
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• pp.155-173
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• 2015

The purpose of this study is to offer the implication for elementary school mathematics teaching by analyzing teachers' reflection on the cognitive demands of mathematical tasks they give in class. During the setup phase and the implementation phase in math class, the researchers analyzed the change of cognitive demands on mathematical tasks and the factors which had influence on such changes. After teachers' reflection on teaching, the researchers analyzed the change of cognitive demands on mathematical tasks and the factors which had influence on such changes in math classes. As a result, before teachers' reflection on the cognitive demands of mathematical tasks, the higher-level demands of mathematical tasks had a tendency to decline. However, after teachers' reflection on the cognitive demands of mathematical tasks, higher-level demands of mathematical tasks were maintained.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.271-271
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• 2013

The defect states of a Ar-sputtered SiO2 surface on Si (001) were investigated using Auger electron spectroscopy (AES) and reflection electron energy loss spectroscopy (REELS). The REELS spectra at the primary electron energy of 500 eV showedthat three peaks at 2.5, 5.1, and 7.2 eV were found within the band gap after sputtering. These peaks do not appear at the primary electron energies of 1,000 and 1,500 eV, which means that the defect states are located at the extreme surface of a SiO2/Si thin film. According to the calculations, two peaks at 7.2 and 5.1 eV are related to neutral oxygen vacancies. However, the third peak at 2.5 eV has never been previously reported and the theories proposed that this defect state may be due to Si-Si bonding. Our Auger data showed that a peak for Si-Si bonding at 89 eV appears after Ar ion sputtering on the surface of the sample, which is consistent with the theoretical models.

• Journal of The Korean Association For Science Education
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• v.37 no.4
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• pp.553-564
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• 2017

This study investigated the change of pre-service elementary teachers' professional visions through video-based reflection on science teaching with focus on their attention and pedagogical reasoning about student learning. Specifically, we compared two reflection cycles before and after pre-service elementary teachers went through the collaborative video-based reflection process in a professional learning community. The primary data were collected from eight pre-service elementary teachers and included their science lesson plans, videotaped lessons, video-reflection papers, and transcripts from the interviews. Pre-service elementary teachers' attention was categorized in five aspects: classroom management & control, teacher's instruction, students' thinking & learning, subject knowledge, and assessment. The level of their pedagogical reasoning about student thinking and learning was determined with six levels based on the number of evidence, evidence area, and evidence type. The findings revealed that 1) individual reflection is not enough - collaborative reflection is essential to change their attention toward students learning and thinking 2) pedagogical reasoning levels increase gradually throughout the individual and collaborative video-based reflection processes. The participants not only attributed student learning solely to the characteristics of students but also connected it with their own instruction or science content knowledge and used different types of evidences as they went through two reflection cycles. Implications for using video in the teacher education program were discussed.