• Title/Summary/Keyword: Reflection Characteristics

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The Patterns and Characteristics of Preservice Elementary Teachers' Reflection in Reflective Journal Writing (초등 예비 교사의 반성적 글쓰기에서 나타나는 반성의 유형과 특징)

  • Lee, Jeong-A
    • Journal of Korean Elementary Science Education
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    • v.29 no.3
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    • pp.378-388
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    • 2010
  • This study aimed at categorizing preservice teachers' reflections and understanding their characteristics in reflective journal writing after microteaching. Thirty-two preservice elementary teachers joined in this study. As results, three patterns were categorized: Reflection with practice, Reflection to be practice, Reflection with suspension of judgment. 'Reflection with practice' changed the topology of science class in active. 'Reflection to be practice' had clear focus in reflection and suggested orientations to succeed in the next teaching. 'Reflection with suspension of judgment' made something fall into abeyance, because it couldn't provide an orientation for teaching. After discussing these results, implications toward preservice teacher education were explored.

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Evaluation of the characteristics of the reflection plate to measure defects in the invisible area using infrared thermography

  • Kim, Sang Chae;Park, Il Cheol;Kang, Chan Geun;Jung, Hyunchul;Chung, Woon Kwan;Kim, Kyeong Suk
    • Nuclear Engineering and Technology
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    • v.52 no.4
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    • pp.856-862
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    • 2020
  • Defect inspection system for industrial applications takes the important portion. Non-destructive inspection method has been significantly improved. Infrared thermography, as one of method for non-destructive inspection, can provide relatively precise data and quick inspection time. This study, it was performed to measure defect according to the measurement limit of the non-visible areas such as the back surface of the pipe using reflection plate using reflection plate based on Infrared thermography. The materials of the reflection plate were determined in consideration of the space limitation and the thermal characteristics, and defects were detected by the manufactured reflection plate. Detection of defect in non-visible area using the candidate materials for reflection plate was conducted.

Optical Characteristics of Nanocone-patterned c-Si Wafers Coated with Dielectric Thin Films (유전박막이 도포된 나노원뿔 패턴된 단결정 Si 기판의 광특성)

  • Kim, Eunah;Park, Jimin;Ko, Eun-Ji;Kim, Dong-Wook
    • Current Photovoltaic Research
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    • v.5 no.2
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    • pp.55-58
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    • 2017
  • We investigated the influences of dielectric thin film coating on the optical characteristics of c-Si wafers with nanocone (NC) arrays using finite-difference time-domain (FDTD) simulations. Dielectric thin films on high-refractive-index surface can lower optical reflection and reflection dips appear at the wavelengths where destructive interference occurs. The optical reflection of the NC arrays was lower than that of the dielectric-coated planar wafer in broad wavelength range. Remarkable antireflection effects of the NC array could be attributed to beneficial roles of the NCs, including the graded refractive index, multiple reflection, diffraction, and Mie resonance. Dielectric thin films modified the optical reflection spectra of the NC arrays, which could not be explained by the interference alone. The optical properties of the dielectric-coated NC arrays were determined by the inherent optical characteristics of the NC arrays.

Analysis of the Reflection Characteristics of a Rectangular Corner Cube Retro-Reflector (사각면 코너 큐브 재귀 반사체의 반사출력광 특성 및 응용)

  • Jeong, Yong-Beom;Kim, Young-Hoon;O, Beom-Hoan
    • Korean Journal of Optics and Photonics
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    • v.26 no.1
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    • pp.17-22
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    • 2015
  • The applications for retro-reflectors, with their unique reflection characteristics, have been expanding, to include venetian blind slats, displays, traffic safety mark, etc. We propose expandable structures of inclined corner cube retro-reflectors and analyze their corresponding reflection characteristics. Various traffic safety structures with retro-reflectors may be designed more quantitatively using the chart of characteristics we have presented.

Characteristics of Elementary Teachers' Reflection on Their Science Teaching Examined through Their Reflective Journals (수업 반성 저널을 통해 살펴 본 초등 교사의 과학 수업 반성의 특징)

  • Yang, Ki Chang;Yoon, Hye-Gyoung
    • 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.

Preparation of Polystyrene Thin Films Containing Bragg Structure and Investigation of Their Photonic Characteristics (Bragg 구조를 갖는 Polystyrene 박막필름의 제조방법과그들의 광학적 특성 조사)

  • Cho, Sungdong
    • Journal of the Chosun Natural Science
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    • v.3 no.3
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    • pp.138-142
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    • 2010
  • Polystyrene thin films containing Bragg structures have been successfully obtained by the removal of DBR porous silicon films from the DBR structured porous silicon/polystyrene composite film in HF/$H_2O$ mixture solution and by replicating the nano-structures of porous silicon containing Bragg structure. Polystyrene thin films containing Bragg structures displayed unique optical reflection resonances in optical reflection spectrum. This optical reflection band was resulted from the interference of reflection wavelength at Bragg structure of polystyrene thin films. The wavelength of reflection resonances could be modified by the change of Bragg structure of the master. Polystyrene thin films containing Bragg structures were flexible and maintained their optical characteristics upon bending. The Polystyrene thin films replicate the photonic features and the nanostructure of the master.

Design of reflection type low phase shift attenuator (반사형 저위상 변화 감쇠기의 설계)

  • 강민수;강원태;장익수
    • Journal of the Korean Institute of Telematics and Electronics D
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    • v.34D no.9
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    • pp.1-6
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    • 1997
  • A transmission type phase shift attenuator has a poor reflection characteristics at an output port. And that is controlled by the current, its dynamic rnage decreases due to the current limitation. In this paper, to avoid such disadvantages, a reflection type low phase shift attenuator has been designed and measured. As a result, at a center frequency (1855MHz), the sreflection type low pahse shift attenuator has an attenuation of 30dB, within the limit of 3 phase shift and less than -17dB reflection characteristics at both input and output ports. And it demonstrates the peformance of the reflection type low phase shift attenuator is better than the transmission type phase shift attenuator with the same measurement specifications.

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Note on the Two-Microphone Methods for the Measurement of Acoustic Impedance (음향 임피던스 측정을 위한 이중 마이크로폰 기법에 대한 고찰)

  • SEO, SEONGHYEON
    • Transactions of the Korean hydrogen and new energy society
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    • v.29 no.2
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    • pp.163-169
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    • 2018
  • The present article discusses about the measurement techniques of acoustic impedance that becomes one of the important acoustic characteristics of various boundaries found inside of propulsion systems. Acoustic characteristics including acoustic impedance and reflection coefficient can be often assessed and estimated by use of the two-microphone method. Theoretical expressions of acoustic impedance and reflection coefficient measured in an impedance tube are presented for both cases with mean flow and without flow, and the practical application of the method through calibration is also provided. The acoustic impedance and the reflection coefficient are related with axial locations of microphones, thermodynamic characteristics of gas inside, and the transfer function between the pressure wave measurements at multiple locations.

Tuned Optical Reflection Characteristics of Chemically-Treated Ti Substrates

  • Yun, Ho-Gyeong;Kim, Myoung;You, In-Kyu
    • ETRI Journal
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    • v.34 no.6
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    • pp.954-957
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    • 2012
  • Titanium foils for use in photoelectrochemical devices are treated with a $HNO_3$-HF solution. After this treatment, the optical reflection characteristics of the Ti substrates are markedly increased in terms of not only reflectivity but also optimized wavelength. Furthermore, the "multiple beam interference" theory and optical analysis of surface morphologies clearly verify the origin of the optimized optical reflection properties.

Spectral Radiative Characteristics of Heat Resisting Ceramics Materials (내열성 세라믹스 재료의 분광복사특성)

  • Sang, Hie Sun
    • Journal of the Korean Society of Industry Convergence
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    • v.4 no.1
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    • pp.35-40
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    • 2001
  • A spectral measurement system for reflection and transmission properties by using an optical fiber and an ellipsoidal mirror was newly developed. The hemispherical reflectance and transmittance spectra of several heating resisting ceramics materials were measured from visible to middle infrared region. The directional characteristics of reflection and transmission were also investigated in consideration of the absorptance. The measured data were analyzed by using a four flux model of radiation transfer, The radiation properties could be estimated by the obtained scattering and absorption coefficient spectra.

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