• Journal of Gifted/Talented Education
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• v.26 no.1
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• pp.101-122
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• 2016

The purpose of this study is to explore a possibility finding gifted underachievers who have high spatial ability, but low verbal ability in elementary science field. In Korea, because teachers used to refer students' academic achievement only when they recommend gifted students, underachievers used to be excluded. The participants are 5th-grade students in elementary school. In this research, developed teaching materials were given to students to find underachievers. Results of spatial ability test, verbal ability test, science academic achievement, non-verbal test, and interviews about light propagation concept were obtained. By analyzing results of this study, we found that spatial ability is the most important factors to understand light propagation. And there are some features to understand light propagation according to spatial ability. Lastly, this study shows the possibility of non-verbal test to find gifted underachievers with high spatial ability and low verbal ability.

• Journal of Science Education
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• v.35 no.2
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• pp.173-192
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• 2011

The purpose of this study was to develop inquiry modules for learning straight propagation of light, to verify their efficiency, and to acquire implications. this study proposes teaching modules for improvements of light experiments, which were developed in this work. Inquiry modules were applied to 75 school teachers(8 elementary school teachers, 67 middle school and high school teachers) for examining that the modules make teachers have the scientific concepts. Then, conception changes were analyzed except 5 teachers who responded poorly. The pre-test result shows that most teachers have alternative conceptions, which is that they thought the bright shape on apparatus's bottom panel itself shown in the textbook as evidence for the path of light's straight propagation. The post-test result shows this alternative conception was changed into scientific conception. Unlikely pretest, most teachers' conception was changed into the scientific conception that the light come from a light source. Teachers are able to express that the light beam comes from a miniature electric bulb. Further more, most teachers can draw light's path correctly; from the miniature electric bulb, through vertical panel having a hole, to the apparatus bottom.

• Journal of Science Education
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• v.38 no.3
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• pp.703-717
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• 2014

In physics, metal simulation is an important mechanism to understand and create concepts. If students have difficulty in mental simulation, understanding the concept of physics also gets difficult. By providing guide for spatial manipulation to students, 3D simulation contents can help them understand the concept of physics. In this study, the 3D simulation contents developed to help understanding the concept of light going straight and shadow is applied to 20 college students. The results, Hake gain is 0.93, showing high level of understanding about the class. In addition, through mental simulation, students predict the phenomenon well about the new context. This is shown that students' understanding of concept through 3D simulation contents are carried out well.

• Journal of the Korean Society for Marine Environment & Energy
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• v.16 no.4
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• pp.263-267
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• 2013

In this research, a novel optical measuring methodology for the measurement of oil thickness in seawater is suggested by evaluating the light absorption which is occurred in the process of penetrating through oil layer on seawater. Laser having monochromatic wave is used as a light source and photodiode which can convert the intensity of the light into an electrical signal is applied to measure the intensity of the penetrating light through the oil-water mixtures. In the experiment, bunker C and lubricating oil are used, and three different lasers having different wavelengths are applied and compared for the selection of an optimal light source. As a result, it is observed that in the case of blue laser, the intensity of the light on the optical sensor decreases with an increase in the oil thickness. Through this relation, both the presence of oil and the thickness of oil can be determined.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.311-311
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• 2004

1960년 레이저가 발명된 이래 레이저의 응용연구가 많은 비중을 차지하여 오늘날 다양한 방면에서 레이저가 필수적인 장치로 각광을 받게 되었다. 레이저의 특성들 중에서 특히 직진성, 에너지 집중도 및 고휘도성을 이용하여 용접, 절단, 각인 등의 산업적 응용에 많이 활용되고 있다 그 중 레이저가 보통의 빛과 같이 투명한 물체를 통과하고 특수한 렌즈를 이용하면 투명한 물체의 내부에 초점을 맞춰 크랙(crack)을 낼 수 있는 바 이를 이용하여 크리스탈이나 유리의 내부에 2차원 형상이나 3차원 형상을 각인시킬 수 있다.(중략)

• Journal of Adhesion and Interface
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• v.23 no.2
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• pp.39-43
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• 2022

In optoelectronic devices including displays and solar cells that convert electricity into light or light into electricity, it is important to control optical behavior of light to improve device efficiency. Specifically, the control of internal emitting light in the OLEDs can induce more light to go out, improving luminous efficiency. In addition, the control of optical behavior of incident light in solar cells can increase optical path in the light absorption layer, increasing power-conversion efficiency. In this study, we generated wrinkles as a physical structure to control optical behavior of light and independently controlled their wavelength and height by changing stress relaxation time. To explore the effect of wavelength and height on optical behavior, we conducted UV/Vis spectroscopy analysis of wrinkles with various heights at a constant wavelength or various wavelengths at a comparable height, figuring out a wrinkle with high aspect ratio has more dispersive light and less straight light. It indicates that high aspect ratio is required to change the optical behavior and increase the optical path.

• Journal of Science Education
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• v.38 no.1
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• pp.182-195
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• 2014

Ray drawing in geometrical optics is an effective method for visible imagery of light. In this study, we developed peer instruction materials for in-service teachers' training concepts on the refraction of light including drawing rays. And then we applied these programs to 29 pre-service teachers and 21 in-service primary teachers and evaluated the degree of conceptual change in correct points from the pretest and the post one. As a result of pretesting, in spite of experiences for learning this topic in elementary and secondary education courses, most participants in the study did not well understand the path of refracted light before instructions. However, the result of post testing after the application of peer instruction materials shows that they have practiced ray drawing, which is helping visible imagery. Accordingly, in learning geometrical optics, we suggest that peer instruction with ray drawing activity for teachers' training program would be effective. We also suggest that similar approaches would be applied to other context.

• Journal of Digital Convergence
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• v.13 no.10
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• pp.319-325
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• 2015

We proposed the blocking channel to reduce the performance decrease using the low correlation with cyclic delay scheme in LED-ID system. LED-ID is based on the visible light to transmit the data. However, It is occurred the block channel by structure or environment of indoor for light of straightness. LED-ID system is degraded the performance by the block channel as loss of data, and burst error. To solve the block channel, the proposed system is overcome the burst error by low correlation among data, which is able to obtain the maximize time diversity gain to improve the performance of BER by cyclic delay scheme. The BER performance is evaluated by computer simulation according to channel parameter. The simulation results shows that proposed system gives much better performance than conventional system and constant cyclic delay scheme system.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.6
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• pp.91-97
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• 2018

This paper presents implementation possibilities of digital IoT doorlock systems via VLC(Visible Light Communication)'s color grid. The color grid-based VLC modulation scheme which are discussed in this paper utilize the straightness of light and abundant frequency resources which are the properties of the light. Performance results in this paper are compared to that of conventional modulations with Bit Error Rate (BER) and Signal to Noise Ratio (SNR) simulations. With respect to a channel model, the proposed modulation schemes select the nearest Line Of Sight (LOS) except Non Line Of Sight (NLOS). Experiments in this paper show error rates of received symbols by changing power dB at a distance of 3m between Tx and Rx in an indoor environment. Through performance results and experiments, this paper demonstrates superiority of the proposed color grid-based modulation schemes.

• Proceedings of the KIEE Conference
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• 2008.10b
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• pp.294-295
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• 2008

본 논문에서는 검사 및 측정용 비젼 시스템에서 카메라와 평면거울을 이용하여 영상을 촬영할 패 발생하는 왜곡의 보정 방법을 제안한다. 빛이 거울과 카메라 사이를 통과할 때 거울 위치의 틀어짐으로 인하여 직진성을 보장받기 어렵다. 이러한 문제점을 해결하기 위하여 왜곡 영상에 대한 모델을 구하고 이를 해결하는 방법을 제시한다. 거울의 위치의 틀어짐은 영상 촬영시 일그러진 사각형 형태로 왜곡이 나타난다. 이 특성을 이용하여 사각형 형태의 실험 대상체를 생성하여 이를 촬영하고 왜곡의 정도를 측정하여 평면거울의 보상값을 구한다. 이 방법으로 평면거울의 자세를 보정하여 왜곡되지 않은 영상을 얻을 수 있다.