• 제어로봇시스템학회논문지
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• 제17권2호
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• pp.116-124
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• 2011

A service robot can identify its own position relative to landmarks, the locations of which are known in advance. The main contribution of this research is that it gives various ways of making the self-localizing error smaller by referring to special landmarks which are developed as high gain reflection material and coded array associations. In this paper, the authors propose a set of indices to evaluate the accuracy of self-localizing methods using the selective reflection landmark and infrared projector, and the indices are derived from the sensitivity enhancement using 3D distortion calibration of camera. And then, the accurarcy of self-localizing a mobile robot with landmarks based on the indices is evaluated, and a rational way to minimize to reduce the computational cost of selecting the best self-localizing method. The simulation results show a high accuracy and a good performance.

• 한국초등과학교육학회지:초등과학교육
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• 제32권4호
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• pp.527-534
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• 2013

This study investigated elementary school teachers' understanding of the image formation by converging lens, pinholes camera, mirror and water. In each case teachers were asked to draw the ray diagram to indicate the position of the image. Teachers' ray diagrams were analyzed in accordance with the scientific process of image formation. Results of analysis showed that teacher's conceptions were classified into five levels for each situation. And most of the teachers were in level 3 and level 4 in each case. Because they had difficulties in the appling scientific conception(propagating path of light, diffused reflection from each object point, role of the eye, ray tracing) to finding location of image. Also most of teachers didn't know how to apply the law of reflection and refraction to each situation. The study finally discussed the teacher training program of the optical image.

• Nuclear Engineering and Technology
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• 제52권12호
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• pp.2847-2851
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• 2020

A simple water level measurement method based on wavelength division multiplexing (WDM) is proposed and demonstrated. The measurement principle is based on the change of Fresnel reflection occurring at the end facet of the optical fiber tip (OFT). To increase the spatial resolution of water level sensing, a broadband light source (BLS) and an arrayed waveguide grating (AWG) are employed. The OFTs are multiplexed with the dedicated wavelength channels of AWG. By measuring all of the reflection powers reflected at the OFTs with a proposed on-site reflectometer, the water level can be monitored continuously for a fast emergency response. Moreover, it can be implemented easily with the commercially available optical components and devices with the simple configuration.

• 정보저장시스템학회논문집
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• 제9권1호
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• pp.10-16
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• 2013

Through the rapid development of LED TV, a large-area edge-lit backlight unit is widely researched in the display industry for enhancing the optical efficiency, luminous uniformity and slim design. In addition, an edge-lit backlight unit includes many optical sheets such as reflection sheet, prism sheet and diffuser sheet. However the function can be replaced by the carefully patterned light guide plate (LGP). Micro patterns which located on the top and bottom surface of light guide plate was designed by ray-tracing optical simulation. The designed patterns improved the light characteristics of LGP, including optical extraction efficiency and intensity distribution uniformity. These results suggest that it is very effective method to design edge-lit LGP with micro-patterns on both sides for large-area display and to reduce the fabrication cost.

• Plant Resources
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• 제7권1호
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• pp.77-86
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• 2004

The reduced ratio of red:far-red (R:FR) light acts as a measure of the proximity of competitors and plants can detect the potentially competing neighbor plants by perceiving reflected R:FR signals and initiate the response of “shade avoidance” before actual shading occurs. The phytochrome system is responsible for monitoring the changes in the R:FR and initiating the shade avoidance response. The response to low R:FR ratio was studied in a white aspen Populus alba clone ‘Bolleana’ using two filter systems: a clear plastic filter system that allows a R:FR ratio less than 1.0 to pass from adjacent border plant reflection; and a special commercial plastic that blocks FR light and creates a R:FR ratio above 3.0. The reduced R:FR signals enhanced the stem elongation in response to competition at the expense of relative stem diameter growth. Trees grown inside clear chambers were 27 ％ taller than trees grown inside the FR-blocking filter chambers. Stem taper of clear chamber trees was 16％ less than the FR-blocking filter trees. Low R:FR also induced 22％ more stem dry weight and 13％ greater petiole length per leaf compared to the FR-blocking filter trees. There were no statistically significant differences in leaf area, leaf number increment, and total dry weight between the two light filter treatments.

• 센서학회지
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• 제30권6호
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• pp.415-419
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• 2021

We developed a highly accurate, yet inexpensive, refractive index (RI)-based soil moisture sensor. To detect the RI, a light guide was set with a light-emitting diode and photodiode. When the air fills the space between the soil particles, most of the incident light is reflected at the interface between the waveguide and the air because of the large RI difference. As the moisture of the soil increases, the macroscopic soil RI increases. This allows incident light to pass through the interface. The intensity of the light reaching the photodiode was simulated according to the change in the soil RI. Using the simulation results, we designed and manufactured a curved glass waveguide. We evaluated the performance of the RI-based soil sensor by comparing it with a commercially available, high-cost and high-performance time-domain reflectometer (TDR). Our sensor was 96% accurate, surpassing the costly TDR sensor.

• 마이크로전자및패키징학회지
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• 제24권2호
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• pp.55-59
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• 2017

본 논문은 마이크로 BGA(Ball Grid Array)의 3차원 형상 검사를 위한 광학적 방법에 관한 것으로, 특히, LED를 공간적으로 배치한 광원과 경면반사특성을 이용하였다. 이를 위해 비전시스템을 구성하여 BGA의 반사영상을 취득한 후, 영상처리를 통하여 반사된 LED 점광원의 위치를 추출하여 형상검사에 이용하였다. 또한, 영상에 포함된 복수개의 BGA에 대한 상대적 위치의 통계치를 이용하여 BGA 3차원 형상의 결함을 판단하는 방법을 제안하였고, 실험을 통하여 제안된 방법의 효용성을 보였다.

• Journal of Multimedia Information System
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• 제5권2호
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• pp.87-90
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• 2018

Various approaches have been proposed to convert low dynamic range (LDR) to high dynamic range (HDR). Of these approaches, the Multi Scale Fusion (MSF) algorithm based on Laplacian pyramid decomposition is used in many applications and demonstrates its usefulness. However, the pyramid fusion technique has no means for controlling the luminance component because the total number of pixels decreases as the pyramid rises to the upper layer. In this paper, we extract the reflection light of the image based on the Retinex theory and generate the weight map by adjusting the reflection component. This weighting map is applied to achieve an MSF-like effect during image fusion and provides an opportunity to control the brightness components. Experimental results show that the proposed method maintains the total number of pixels and exhibits similar effects to the conventional method.

• 한국광학회지
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• 제26권5호
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• pp.275-282
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• 2015

단축이방성 박막들과 등방성 박막들이 코팅되어 있는 시료에 비스듬히 입사한 빛의 유효반사계수 표현들을 유도하였다. 단축 이방성 박막 내에서의 다중반사 효과를 반영하여 여러 층의 등방성 박막들과 이방성 박막들이 섞여 있는 시료의 유효반사계수 표현들과 타원상수 표현들을 제시함으로써 시료면에 수직한 방향으로 균일하지 않은 단축이방성 분포를 가진 시료의 광학이방성을 여러 개의 단축이방성 박막으로 나누어 분석할 수 있도록 하였다.

• 한국결정성장학회지
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• 제3권2호
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• pp.162-166
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• 1993

적외선 할로겐 lamp를 열원으로 하는 image furnace을 사용하는 Floating Zone process를 이용하여 Spodumene$(LiAlLi_2O_6)$ 단결정을 성장하였다. 결정의 길이는 50~60mm, 직경 6~8mm였고 dopant에 따라 녹색, 흑색, 연한 녹색의 결정을 얻었다. Spodumene 조성의 고찰을 위해 XRD와 FTIF을 조사하였으며, Laue back reflection pattern을 통해 결정성을 고찰하였다. 결정의 광투과도 측정을 위해 optical transmittance를 측정하였다.