• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.10 s.103
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• pp.1131-1136
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• 2005

For the accurate measurement of acoustic properties of a surface, efforts have been made to reduce errors caused by external disturbance. If the reflection coefficient is considered as a transfer function between reflected wane and incident wave, the causality is required between them and the reflection coefficient should be of minimum phase. In this thesis, the minimum phase condition is applied to measure correct reflection coefficient. The reflection coefficient is approximated as a rational function In the Z domain by minimizing the sum square error. Then the minimum phase reflection coefficient is reconstructed using the distribution of poles and zeros of the reflection coefficient model.

• The Journal of the Society of Korean Medicine Diagnostics
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• v.19 no.1
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• pp.47-54
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• 2015

Objective Wave reflection is an important factor that determines the shape of the pulse wave. The purpose of this study is to compare the conventional method used for estimating the reflection site of pulse with a cardiovascular simulator. Methods: In this study, cardiovascular simulator with one elastic tube was used. The pressure and flow was measured simultaneously at three different points. The measured data were used to the conventional methods to estimate the pulse wave reflection site. The results were compared with the known length which were the distances from the measured points to the end of tube. Results & Conclusions: There is a significant error with the time domain method. While, the reflection site with the frequency domain method was similar to the actual reflection site.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.20 no.4
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• pp.370-378
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• 1987

Wave reflection control functions of mound for the foundation of composite and perforated break-waters were investigated through the theoretical considerations. The theory developed is based on a simple summation of components of reflected waves. The applicability of the theory is assured by the comparative studies of the theoretical calculation and experimental data on the sea surface elevation in front of a breakwater. It is found that the reflection is mainly controlled by depth and width of the mound. In the design of composite type perforated breakwaters, the width of perforated part of the upright section can be decreased to less than half of the conventional design width for the same reflection by using the reflection control function of mound part and the reflection can be reduced until less than $30\%$ of that in the composite breakwaters. Using the results, a design method of mounds is proposed, by which the reduction of wave reflection is assured under the given wave conditions.

• Journal of Korean Elementary Science Education
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• v.31 no.3
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• pp.372-385
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• 2012

For decades, reflection has been recognised as a meaningful tool to bring forth teachers' ownership as well as knowledge and action empowerment in teacher education. Yet there have been few studies on elementary teachers' reflection on their science teaching in Korea. In this study, 71 reflective journals of 24 elementary teachers on their science teaching were analyzed. The characteristics of reflective journals were analyzed in terms of 'productive reflection', a concept suggested by Davis (2006). Unproductive reflection is mainly descriptive without analysis, whereas productive reflection can promote teachers' learning by integrating four aspects of teaching (learner/learning, subject matter knowledge, instruction and assessment). The result showed what elementary teachers consider and emphasize and how they integrate their ideas. Most of reflective journals included aspects of 'instruction', 'learner/learning', and 'subject matter knowledge'. However 'instruction' was emphasized most frequently (69.0%) than 'subject matter knowledge' (33.8%) and 'learner/learning' (26.8%). 'Assessment' was hardly included nor emphasized. More than half of the journals (56.3%) showed no integrations, which were unproductive reflection. A third of the journals (32.4%) integrated only two aspects among four. Average score of integrations was 1.6 on a scale of 4 points. The integrations were not affected by the length of reflective journals and the teaching experience. These findings suggest that productive reflection would not increase naturally with teaching experience and there needs more tactful guidance to develop elementary teachers' productive reflection on their science teaching.

• Journal of Korean Elementary Science Education
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• v.32 no.2
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• pp.113-126
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• 2013

In this study, the researcher aimed to increase productive reflection of pre-service elementary teachers through reflective journal writing and discussion after science peer teaching practice. 'Productive reflection' involves consideration and analysis of interrelationships among aspects of teaching including learners and learning, subject matter knowledge, assessment, and instruction. During 8 week efforts, productive reflection has increased gradually in both individual journal and class discussion. However half of individual journals didn't show productive reflection even in the final stage. This implicated that development of reflective thinking is an achievable but progressive change. By describing the progress in discussion and participants' responses on journal writing and discussion activity, this study shed light on practical ways of enhancing reflective teacher education.

• Journal of the Korea Computer Graphics Society
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• v.20 no.1
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• pp.13-19
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• 2014

In this paper, we introduce a real-time method to render a 3D scene using image-based lighting. Previous approaches for image-based lighting focused on diffuse reflection and mirror-like specular reflection. In this paper, we provide a simple preprocessing approach to efficiently approximate Phong reflection model, which has been used for computer graphics applications for several decades. For diffuse reflection, we generate a texture map for diffuse reflection by integrating the source image in preprocessing step, similarly to the previous approaches. We adopt the similar idea to produce a set of specular reflection maps for various material shininess. By doing this, we can render a dynamic scene without high computational complexity or numerous texture map access.

• The Journal of the Convergence on Culture Technology
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• v.9 no.6
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• pp.105-111
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• 2023

The purpose of this study is to find out what self-reflection, relationship reflection, gratitude and happiness reflection, and social reflection among the sayings of Confucius in the Analects of Confucius are reinterpreted in various ways depending on the times and what meaning they contain today. Self-reflection is the process of considering one's identity, values, emotions, thoughts, and actions. Humans grow through reflection because they can identify their own problems, acknowledge their mistakes, find opportunities for improvement, and set a direction for the future. Confucius pursued the life of a gentleman as a person who constantly reflects on his life and grows. We classified it into the four categories presented above and examined them. In an era of coexistence with generative AI, Confucius' reflective life and teachings are recognized as important values in modern society in terms of human-centered value orientation, mature human relationships, and continuous social value realization, and reflection on happiness is the best attitude to life.

• The Journal of the Acoustical Society of Korea
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• v.28 no.3
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• pp.174-186
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• 2009

When we apply a propagation model to the ocean with boundaries, we can calculate reflected wave using reflection coefficient suggested by Rayleigh assuming the boundaries are flat. But boundaries in ocean such as sea surface and sea bottom have an irregular rough surface. To calculate the reflection loss for an irregular boundary, it is needed to compute the coherent reflection coefficient based on an experimental formula or scattering theory. In this article, we derive the coherent reflection coefficients for a fluid-fluid interface using perturbation theory, Kirchhoff approximation and small-slope approximation respectively. Based on each formula, we can calculate coherent reflection coefficients for a rough sea surface or sea bottom, and then compare them to the Rayleigh reflection coefficient to analyze the reflection loss for a random rough surface. In general, the coherent reflection coefficient based on small-slope approximation has a wide valid region. Comparing it with the coherent reflection coefficients derived from the Kirchhoff approximation and perturbation theory, we discuss a valid region of them.

• Journal of the Korean housing association
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• v.24 no.6
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• pp.33-40
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• 2013

Hiroshi Hara is one of the most famous architect in the history of contemporary Japanese architecture. During the 1970's beginning with the Awazu Residence (1972), he designed a series of symmetrical houses, the so called 'Reflection House'. All the houses in this period were based on the method of 'reflection' and 'inversion', which means a radical reversal of the accepted notion that houses are parts of cities. A concept of "A house within a house" is expanded to "A city within a house". The important spatial characteristics of 'Reflection House' are main internal core and valley-like spaces forming internal urban streets by bringing natural elements and the components of streetscape such as plaza, open space, context of street facades and so on. This procedure is called as embedding 'city' into 'house', Hara mentioned. This paper investigates the outline of the 'Reflection House' and analyses the completed works of housing that were based on the theory. Then in the final part of the paper, the implications of 'Reflection House' and its influence on his later works of following period will be discussed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.5
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• pp.852-857
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• 2006

This paper presents a precision method to calculate the electric field density of mountain area using digital terrain elevation data(DTED). Generally we calculate the electric field density of a point adding a direct field density and horizontal reflection field density between two points. In this paper, we consider a vertical reflection field density from vertical surface near the wave propagation line between transmitter and receiver. The vertical reflection electric field have different propagation path and polarization from a horizontal reflection field. And the total electric field density adding horizontal field density and vertical reflection value is more accurate than a direct path electrical field density or direct field density adding a horizontal reflection field density.