• Journal of Korean Ophthalmic Optics Society
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• v.15 no.1
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• pp.67-71
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• 2010

Purpose: The effect of two different levels of illumination and the effect of three letter chart types on subjective refraction findings were investigated. Methods: This study involved thirty Malay university students aged between 19 to 23 years old (7 males, 23 females), with their spherical refractive error ranged between plano to -7.75D astigmatism ranged from plano to -1.75D, anisometropia less than 1D and with no history of ocular injury and pathology. Monocular subjective refraction was measured under two levels of illumination (with and without room light) and with three different letter charts (Snellen letter chart, wall mounted letter chart and projected letter chart). Subjective refraction finding was calculated in spherical equivalent in unit diopter (D). Results: There was no significant effect in the subjective refraction findings with Snellen letter chart (t-test=0.15, p-value=0.88), projected letter chart (t-test=-0.19, p-value=0.85) as well as wall mounted letter chart (t-test=0.12, p-value=0.94). One Way ANOVA also revealed when the subjective refractive measures were compared under two different level of room illumination (with and without room light), no significant effect of letter chart types on subjective refraction readings with room light ($F_{2.185}$=0.11, p-value=0.89) and without room light ($F_{2.185}$=0.02, p-value=0.98). Conclusions: Subjective refraction findings were not affected whether the room light was on or off. They were also not affected by the types of letter chart used.

• Journal of the Optical Society of Korea
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• v.7 no.3
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• pp.174-179
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• 2003

We construct a four-level system where a metastable state is included in an $Er^{3＋}$ Doped Yttrium aluminum garnet (YAG) crystal. Because of the action of the coherent field, the traditional light amplification with inversion can be exhibited with remarkable variation. As a result, we propose a method to achieve the gain equalization by atomic coherence. At the same time, we find that the high index of refraction accompanied by vanishing absorption can also be reached in this model. We also find that a higher index of refraction with zero absorption can be easily obtained when the coherent field is off resonance.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2006.05a
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• pp.3-7
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• 2006

Development of light sources has been constantly grown for a high efficacy and long life. And, the design of luminaires has ben developed for the reflection and refraction of light mechanism. But it has been not enough to study for the refraction of light mechanism. Therefore, this study aims to study for the refraction of light mechanism to using Monte-Carlo method and Ray-tracing method. In addition, the purpose of this study is to shu calculation process for development of 3 dimensional planar prism design algorithm in orer to use the results of photometric data that is able to obtain various luminous intensity distribution.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.2
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• pp.91-95
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• 2019

A new experimental approach is proposed to detect a specific polymer dissolved in a liquid. Distinctive optical properties were found using a laser scattering technique when there is a polymer compound with almost no difference in optical properties (index of refraction) in a liquid phase. The index of refraction, which determines the refraction of light, is obtained by dissolving PCL and PLA. The used samples are biodegradable materials with similar properties and dissolved in a mixture of Chloroform 7: Methanol 3. To predict the optical properties, a 632-nm diode laser was used as the light source of the device, and an integrating sphere was used as the light receiver. Although PCL and PLA had a similar index of refraction of 1.46-1.48, the dissolved PCL showed a relative transmittance of 43%, and the dissolved PLA had a relative transmittance of 34%. The difference in optical properties of the pure polymer compound in the solid state or liquid state is not significantly different, and the difference in the dissolved state in the specific solvent is remarkable because the solubility differs in a specific solution and is randomly distributed.

• Journal of Korean Elementary Science Education
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• v.25 no.spc5
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• pp.548-555
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• 2007

In this paper, we suggested that those elementary school students who are gifted in science should be taught basic and fundamental concepts to solve applied problems. We developed a teaching model based on a lesson regarding the path that light takes when passing through a lens on the base of refraction of light. We applied the teaching model to scientifically-gifted elementary school students and analyzed the results. The teaching model is based on the circulation loaming model appropriate for learning such concepts. The problems were designed and applied in order to determine the students' level of concept skills held and also to develop new teaching tools to help their understanding of concepts. As a result, we confirmed that the students, who were unable to describe the path of the light before the course of instruction was given, were able to draw and explain the path of light passing trough lens by using the law of refraction following the instruction.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2005.05a
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• pp.14-18
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• 2005

It is important to select light sources and luminaires in the process of lighting design. Therefore, development of light sources has been constantly grown for a high efficacy and long life. And, the design of luminaires has been developed for the reflection of light mechanism. But it has been not enough to study for the refraction of light mechanism Therefore, the propose of this study is to study for the refraction of light mechanism. In addition, this study is modeling for the luminous intensity distribution of planar prism to use the results of photometric data that is able to obtain various luminous intensity distribution.

• Journal of the Korea Computer Graphics Society
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• v.13 no.1
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• pp.7-14
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• 2007

In this paper we present an illumination model for rendering realistic stained glass. This techniques simulates the phenomenon of stained glass in real world by applying important optical component of the stained glass to the rendering algorithm. The optics for stained glass involves three basic physical mechanisms. First, diffuse light and highlight contribute to the brightness of stained glass which is typically white and changes along with the light source and the view position. Next, Fresnel refraction dominates the amount of refracted (transmitted) light. Finally, we express volume absorption occurs in all stained glass. Then, the rendered stained glass images achieve excellent realism.

• Journal of the Korea Society of Computer and Information
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• v.4 no.3
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• pp.60-66
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• 1999

The purpose of this study is to design and materialize the simulated courseware which is based on new educational environments and student-based education. The scope of this study is reflection and refraction of in the physics of high school. This paper introduce the theoretical background of courseware and investigate the structure and process of the teaching-theory by visualized computer simulation. We applied the basic concept about the reflection and refraction of light and explained the simulated images of spherical mirror and lens with the principles expressions and relative image forms. The last we simulated the various kinds of the images, shapes and distance of the images by changing the distance of object and focus which are made by computer simulation.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.2019-2023
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• 2005

A aspheric lens is one a key point optical element in the optical industry. The feature of a aspheric lens is not to have the spherical aberration. A aspheric lens is also essential element for high-precision and light-weight in the optical machine. Generally it have been used in a tailor progression an aspheric lens modelling much. In this study we applied a lay back-tracer using a index of refraction to draw a creative aspheric lens. And we executed a comparison experiment for refraction situation of shape and straightness experiment to inspect the drawn aspheric lens in this study

• Journal of Science Education
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• v.45 no.3
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• pp.326-335
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• 2021

In this study, we developed an experimental apparatus to study the principle of rainbow formation. The rainbow is formed through the dispersion, reflection, and refraction of light on water droplets. However, the rainbow cannot be made from a single drop of water. Thus, we devised an apparatus to observe the principle behind the rainbow formation caused by light rays on many water drops. This we deemed would help students understand the formation of the rainbow. We used glass beads as water drops to reproduce the rainbow phenomena. We also materialized the rainbow by changing various variables such as the position of the observer and the height of the light source, etc.