• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.10a
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• pp.365-366
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• 2006

• Journal of Korean Elementary Science Education
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• v.27 no.2
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• pp.102-116
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• 2008

In their teaching practice, teachers encounter multi-dimensions of pedagogical challenges. The recognition and reflection on these challenges is crucial to advance our science teaching. This study looked into science teachers' dilemmas of their teaching practical work through their written cases. Dilemma cases are teachers' narratives organized around important events of teaching and learning. It can reveal teachers' situated cognition and be used as lens to investigate complex realities of science teaching and learning. 26 pre- and in-service elementary teachers' dilemma cases of science practical work were carefully collected and analysed to interpret what constitute tensions in elementary science practical works. They were largely grouped into three: Curriculum and Institutional Relevance, Students Relevance, Nature of School Experiments Relevance and divided into 7 subheadings: 'Authority of Curriculum(textbook)', 'Disappointment at external support', 'Students' interests and safety', 'Students' unscientific and inert attitude', 'Difficulty of showing expected results', 'Generalization through experiment', 'Knowledge acquisition and authentic inquiry'. Each dilemma was interpreted in terms of the tensions which constitute contradictory beliefs, values, expectation and realities. These dilemmas enabled to expose actual conditions of elementary science practical work and teachers' challenges otherwise can not be seen easily. Science teacher educators also can get some implications to overcome the gap between theory and practice in their teacher education.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.14 no.1
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• pp.76-85
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• 2002

The floating breakwater generally has an excellent water exchanging capability, but with some lowering harbor tranquility due to the wave transmission underneath floating body. In the initial stage of design, it is thus required to investigate several alternatives of breakwater layout for their performance of harbor tranquility. The present study aims to formulate a sort of reflection-transmission boundary condition of floating breakwater so that the existing numerical method using time dependent mild slope equation can still be applied to the case of floating breakwaters. The two and three dimensional tests were each performed to demonstrate the performance of the boundary condition. It was found that the reflection and transmission characteristics around the breakwater were well reproduced by the boundary condition. Finally, the reflection-transmission boundary condition were applied to a floating breakwater installed in an imaginary harbor with an irregular shape and bottom topography. The results surely showed that the present numerical method can effectively used in practical works related to the real sea construction of floating breakwaters.

• Journal of the Institute of Convergence Signal Processing
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• v.15 no.3
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• pp.91-96
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• 2014

For Sound source direction and separation method, Frequency Domain Binaural Model(FDBM) shows low computational cost and high performance for sound source separation. This method performs sound source orientation and separation by obtaining the Interaural Phase Difference(IPD) and Interaural Level Difference(ILD) in frequency domain. But the problem of reflection occurs in practical environment. To reduce this reflection, a method to simulate the sound localization of a direct sound, to detect the initial arriving sound, to check the direction of the sound, and to separate the sound is presented. Simulation results show that the direction is estimated to lie close within 10% from the sound source and, in the presence of the reflection, the level of the separation of the sound source is improved by higher Coherence and PESQ(Perceptual Evaluation of Speech Quality) and by lower directional damping than those of the existing FDBM. In case of no reflection, the degree of separation was low.

• Journal of the Korean Chemical Society
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• v.66 no.6
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• pp.459-471
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• 2022

The purpose of this study is to develop the workshop to improve teachers' questions considering the context of discourse. Four pre-service science teachers in the fourth grade participated in the study. Pre-service science teachers participated in the workshop. The characteristics of their reflection on the question considering the context of discourse were analyzed. Pre-service science teachers considered the types of questions they learned in the workshop during the reflection. But the affective domains of students were rarely considered. Whether the students respond was considered as an important factor of reflection. The questions were evaluated based on the frequencies. A single question without context was reflected on. Various PCK elements were not considered comprehensively. Based on the results, the practical implications to develop a program for improving teacher expertise related to the questions considering the context of discourse were discussed.

• Journal of the Korean Ceramic Society
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• v.31 no.1
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• pp.11-16
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• 1994

The impedance matching solution map is not a sufficient method for designing the broad-band absorber because of its difficulty to get numerical data about practical band-width. Therefore, we develope a new method to design the broad-band absorber. The complex permeability limits, which is necessary for designing the broad-band absorber in C-X band (4 GHz~12.4 GHz) were investigated and application was also examined. The complex permeability limits represent the frequency dependence of the complex permeability at a practical frequency band. These complex permeability limits can be used effectively to design broad-band single-layered absorber because they offer numerical data about the band-width in the case of various dielectric loss tangent, practical frequency bands and permitted reflection losses of an absorber.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.11
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• pp.960-967
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• 2013

Shape recognition of solder ball bumps in a BGA (Ball Grid Array) is an important issue in flip chip bonding technology. In particular, the semiconductor industry has required faster and more accurate inspection of micron-size solder bumps in flip chip bonding as the density of balls has increased dramatically. The difficulty of this issue comes from specular reflection on the metal ball. Shape recognition of a metal ball is a very realproblem for computer vision systems. Specular reflection of the metal ball appears, disappears, or changes its image abruptly due to tiny movementson behalf of the viewer. This paper presents a practical shape recognition method for three dimensional (3-D) inspection of a BGA using a 5-step ring illumination device. When the ring light illuminates the balls, distinctive specularity images of the balls, which are referred to as "iso-slope contours" in this paper, are shown. By using a mathematical reflectance model, we can drive the 3-D shape information of the ball in aquantitative manner. The experimental results show the usefulness of the method for industrial application in terms of time and accuracy.

• Journal of the Korea Fashion and Costume Design Association
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• v.8 no.2
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• pp.17-26
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• 2006

As fashion is a reflection of a way of life, jean fashion seems to be a reflection of the background and process of social-human psychology. Modern jeans reflect personality and trend rather than traditional practicality as indicated by the concept and emphasis of fashion. Since the early 1990s, practical use of jeans has appeared consistently in products for interior use, various kinds of fashion-ware and fashion properties, as well as in fashion that is a conversion and interpretation of an outstanding fashion trend. And the search, providing that various symbols of jeans are sensualism, deviation, ostentation, amusement and multi-culture, shows that jeans represent the multifarious aspects of fashion culture. For the purpose and necessity of this search to meet different consumers' desires by the practical use of jeans and the development of fashion-ware. First, investigate the trend of jeans in 2005. Second, try to change the various uses of jeans by reflecting the trend of jeans. Finally, extend the range of choice by developing various goods. As a result, basic jeans have the strength of function, activity, and originality. Use of ornamental jeans can fully show their value as well as their emphasis of individuality in beauty. If we consider these points, we can minimize the limitations of jeans and make a practical use of the fashion trend, If we make the function of jeans stand out through the use of varieties of materials, the modem characteristic consumption will be met by the various change of use as well as by the clothes.

• Journal of the Korean Geographical Society
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• v.44 no.4
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• pp.577-603
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• 2009

The purpose of this study is to understand two geography student teachers' experience of practical knowledge on the geography classroom organization during their student teaching. I carried out a qualitative case study on the geography classroom organization and its practice. Data was gathered through participant observation and in-deep interview. The results are as follows: 1) I present portraits two pre-service geography teachers' lives, which represent typical case of intrinsic deep motivation and spontaneous interest in subject matter. 2) Their classroom are organized $9{\sim}14$ segment, its segment organizations in introduction close steps and main lesson step behave differently. The segment activities in close step behave most irregularly. 3) In the reflection rubric, the level of their reflection is middle, mostly concentrated on 'technical' or 'dialogue' level. On the basis of these findings, it can be concluded that a different way of understanding the relationship between knowing to teach and knowing about teaching is necessary.

• 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.