• Journal of the Korean Society for Nondestructive Testing
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• v.34 no.2
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• pp.119-127
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• 2014

An epoxy coating applied to the concrete surface of a containment building deteriorates in hazardous environments such as those containing radiation, heat, and moisture. Unlike metals, the epoxy coating on a concrete liner absorbs and discharges moisture during the degradations process, so it has a different density and volume during service. In this study, acoustic impedance was adopted for characterizing the degradation of a glass-reinforced epoxy coating using the acoustic reflection coefficient (reflectance) on a rough epoxy coating. For estimating the acoustic reflectance on a wavy epoxy coating surface, a probabilistic model was developed to represent the multiple irregular reflections of the acoustic wave from the wavy surface on the basis of the simulated annealing technique. A number of epoxy-coated concrete specimens were prepared and exposed to accelerated aging conditions to induce an artificial aging degradation in them. The acoustic impedance of the degraded epoxy coating was estimated successfully by minimizing the error between a waveform calculated from the mathematical model and a waveform measured from the surface of the rough coating.

• Journal of the Society of Naval Architects of Korea
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• v.42 no.2 s.140
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• pp.159-164
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• 2005

Monostatic RCS analysis of complex structures has been done with a combined method of physical and geometric optics, commonly applied to high frequency electromagnetic backscattering problems. In the analysis, the complex structure is modeled as a number of flat surfaces and the RCS of whole structure is calculated by summing RCS of each surface, which can be obtained from an analytical solution of flat surface phase integral derived from physical optics. The reflected and hidden surfaces are searched by an object precision method based on adaptive triangular beam method, which can take account for effects of multiple reflections and polarizations of electromagnetic wave. The validity of the presented RCS analysis method has been verified by comparing with exact solutions and measured data for various structures.

• Korean Journal of Optics and Photonics
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• v.9 no.1
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• pp.5-8
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• 1998

In calculating the light propagation in inhomogeneous uniaxial materials by using a conventional $4{\times}4$ matrix method, Fabry-Perot effect is caused by inherent multiple internal reflections at interfaces for monochromatic light source. In this paper we propose an apodization method by which we can eliminate in negligible time the interference fringe in the $4{\times}4$ matrix optics. For a cell with k abrupt interfaces, the new apodization method can be implemented simply by, at maximum, (k+1) addtional $4{\times}4$ matrix multiplications in calculating the complete transfer matrix of the cell.

• Journal of IKEEE
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• v.23 no.2
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• pp.534-537
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• 2019

The optical loss is caused by reflection on the surface of the solar cell, without being absorbed inside the solar cell. Research is actively being conducted to reduce optical loss due to such reflection of light and to improve conversion efficiency of solar cells. In this paper, the surface of the FTO glass substrate was wet etched, and the structural characteristics of the tough surface were evaluated. In addition, optical properties on the surface were analyzed, etched using spectrometer. When light was introduced to a rough surface formed by etching, it was confirmed that the multiple reflections reduced the amount of light reflection from the surface, thereby increaseing the amount of light penetrating the glass substrate.

• SUVANNABHUMI
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• v.11 no.1
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• pp.7-40
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• 2019

The essay reflects on the work of Adrian Lapian (1929-2011), an Indonesian scholar of archipelagic/maritime Southeast Asia and its "sea people-sea pirates-sea kings." The essay suggests that Lapian's writing mirrors navigation at sea, and the constant re-orientation and ever-changing, multiple points of view that are part of it. This is contrasted to Foucault's "panopticism" and academic desire for discipline. Taking cue from Lapian's writing and from the present author's experience of seafaring, the essay envisions Southeast Asian studies as a fluid, precarious, disorienting, even nauseating multiplicity of experiences, dialogues, and moving, unstable, and uncertain points of view; a style of learning that is less (neo)colonial, more humble, and closer to experiences in the region, than super-scholarship that imposes universalizing, panoptic standards, theories and methods (typically self-styled as "new") that reduce the particular into a specimen of the general, a cell in the Panopticon. The essay concludes with reflections on certain learning initiatives/traditions at the National University of Singapore, including seafaring voyages-experiences, encounters, and conversations that make students and scholars alike to move and see differently, to be touched, blown away, rocked, swayed, disoriented, swallowed, transformed, and feel anew their places, roots, bonds, distances, fears, blindness, powerlessness.

• Journal of the Korean Chemical Society
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• v.21 no.1
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• pp.3-15
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• 1977

Crystals of salicylaldehyde-4-morpholinothiosemicarbazone, $C_{12}H_{15}O_2N_3S$, are orthorhombic with space group Pna21. Unit-cell dimensions are a = 11.85(5), b = 15.45(5) c = 7.18(3)${\AA}$ with z = 4. Three-dimensional intensity data were collected from the multiple-film equi-inclination Weissenberg photographs taken with $CuK{\alpha}$ radiation. The intensities were estimated visually. The structure was solved by Patterson and Fourier methods and refined by the block-diagonal least-squares methods until the final R value becomes 0.11 for the 1064 observed independent reflections. The morpholine ring has a chair form. The rest atoms of salicylaldehyde-4-morpholinothiosemicarbazone molecule excluding morpholine ring and sulfur atom approximately lie on a plane. The hydroxyl group of the salicylaldehyde and the nitrogen atom of the thiosemicarbazone form an intramolecular hydrogen bond, $O-H{\cdot}{\cdot}{\cdot}N$, of 2.67${\AA}$. The short intermolecular distances all appear to be normal van der Waals contacts.

• Journal of The Korean Association For Science Education
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• v.41 no.6
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• pp.519-531
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• 2021

This study investigates the science teacher identity of pre-service science teachers (PSTs) in the context of a teaching practice course. Twenty-two PSTs who took the 'Biological Science Lab. for Inquiry Learning' course at the College of Education participated in this study. Artifacts created during the course were collected, and the teaching practices and reflections were recorded and transcribed. In addition, semi-structured interviews were conducted with nine PSTs, recorded, and transcribed. We found the science teacher identity was not well revealed at the beginning of the course. Authoritative discourse appeared in the early oral reflections of PSTs, indicating that the PSTs perceived oral reflection activities as 'evaluation activities for teaching practice'. This perception shows that pre-service teachers participate in teaching practice courses as students attending a university, performing tasks and receiving evaluations from instructors. After the middle of the course, discourses showing the science teacher identity of the PSTs were observed. In the oral reflection after the middle part, dialogic discourses often arose, showing that the PSTs perceive the oral reflection activities as a 'learning activity for professional development'. In addition, in the second half, discourse appeared to connect and interpret one's experience with the teacher's activity, indicating that the PSTs perceive themselves as teachers at this stage. In addition, the perception of experimental classes was expanded through the course. During the course, the practice of equalizing the authority of the participants, providing a role model for reflection, and experiencing various positions from multiple viewpoints in the class had a positive effect on the formation and continuation of the teacher identity. This study provides implications on the teacher education process for teacher identity formation in PSTs.

• Journal of KIISE:Software and Applications
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• v.37 no.2
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• pp.104-109
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• 2010

The lighting reflection is a common problem in image analysis and causes the many difficulties to extract distinct features in related fields. Furthermore, the problem grows in the rainy night. In this paper, we aim to remove light reflection effects and reconstruct a road surface without lighting reflections in order to extract distinct features. The proposed method utilizes a 3D analysis based on a multiple geometry using captured images, with which we can combine each reflected areas; that is, we can remove lighting reflection effects and reconstruct the surface. At first, the regions of lighting sources and reflected surfaces are extracted by local maxima based on vertically projected intensity-histograms. After that, a fundamental matrix and homography matrix among multiple images are calculated by corresponding points in each image. Finally, we combine each surface by selecting minimum value among multiple images and replace it on a target image. The proposed method can reduces lighting reflection effects and the property on the surface is not lost. While the experimental results with collected data shows plausible performance comparing to the speed, reflection-overlapping areas which can not be reconstructed remain in the result. In order to solve this problem, a new reflection model needs to be constructed.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.634-637
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• 2005

Multichannel seismic data acquired in Ulleung Basin of East Sea for gas hydrate exploration. The seismic sections of this area show strong BSR(bottom simulating reflections) associated with methane hydrate occurrence in deep marine sediments. Very limited information is available from deep sea drilling as the risk of heating and destabilizing the initial hydrate conditions during the processing of drilling is considerably high. Not so many advanced status of gas hydrate exploration in Korea, the most of information of gas hydrate characteristics and properties are inferred from seismic reflection data. In this study, The AVO analysis using the long offset seismic data acquired in Ulleung Basin used to explain the characteristics and structure of gas hydrate. It is used primarily P-wave velocity accessible from seismic data. To make a good quality of AVO analysis input data, seismic preprocessing including 'true gain correction', 'source signature deconvolution', twice velocity analysis and some kinds of multiple rejection and enhancing the signal to noise ratio processes is carried out very carefully. The results of AVO analysis, the eight kinds of AVO attributes are estimated basically and some others of AVO attributes are evaluated for interpretation of AVO analysis additionally. The impedance variation at the boundary of gas hydrate and free gas is estimated for investing the BSR characteristics and properties. The complex analysis is performed also to verifying the amplitude variation and phase shift occurrence at BSR. Type III AVO anomaly appearance at saturated free gas area is detected on BSR. It can be an important evidence of gas hydrate deposition upper the BSR.

• The Journal of the Korea Contents Association
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• v.20 no.7
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• pp.503-515
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• 2020

This study was conducted to find out the psychosocial-demographic factors affecting the ambivalent sexism and attitudes toward homosexuality of school health teachers. The data were collected from December 1^st to 31^st, 2019 by administering a structured online questionnaire for 138 school health teachers in S city. The data were analyzed via SPSS/WIN (25.0) to run Kruskal-Wallis 𝑥² test, Mann-Whitney U test, Spearman's rank correlation, and Stepwise multiple regression. The results showed that the influential factors on the hostile sexism include authoritarian personality, age, extrinsic religious orientation, and education. Compared to this, the benevolent sexism had the influential factors of authoritarian personality, age, and education. The influential factors to the attitudes toward homosexuality found to include authoritarian personality, whether or not have a religion, and intrinsic/extrinsic religious orientation. School health teachers affect the educational experiences of students of their gender stereotyping and prejudice in the school environments. Therefore, it is needed to establish and provide training programs for school health teachers so that they can have reflections on their gender perspectives themselves, which may lead to true educational changes based on gender equality.