• 제어로봇시스템학회논문지
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• 제22권10호
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• pp.811-816
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• 2016

In light of recently developed 3D printers for rapid prototyping, there is increasing attention on the 3D scanner as a 3D data acquisition system for an existing object. This paper presents a prototypical 3D scanner based on a striped laser light image. In order to solve the problem of shadowy areas, the proposed 3D scanner has two cameras with one laser light source. By using a horizontal rotation table and a rotational arm rotating about the latitudinal axis, the scanner is able to scan in all directions. To remove an additional optical filter for laser light pixel extraction of an image, we have adopted a differential image method with laser light modulation. Experimental results show that the scanner's 3D data acquisition performance exhibited less than 0.2 mm of measurement error. Therefore, this scanner has proven that it is possible to reconstruct an object's 3D surface from point cloud data using a 3D scanner, enabling reproduction of the object using a commercially available 3D printer.

• 한국정밀공학회지
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• 제21권3호
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• pp.38-43
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• 2004

This paper describes the construction of a circular polariscope. Generally, a circular polariscope contains four optical elements and a light source. The first element following the light source is called the linear polarizer. It converts the ordinary light into plane-polarized light. The second element is a quarter wave plate which converts the plane-polarized light into circularly polarized light. Following the quarter wave plate, a specimen made of transparent photoelastic material is located in a loading device. The second quarter wave plate is set and the last element is the analyzer. These polarizing elements, two quarter wave plates and two linear polarizing filters, were purchased from the USA. Frames and other structures for holding polarizing filters were machined and assembled to be rotated. Light box, which includes four incandescent lamps and two sodium-vapor lamps, was made. In order to proof the function of the newly built polariscope, Tardy compensation test was applied to a rectangular shaped specimen made of poly-carbonate material (PSM 1). The error of the fringe constant, which was measured by the newly built polariscope, was within 4.4 percent compared to the standard value of this material. It is possible to make a good quality of polariscope if accurate polarizing filters will be used.

• 한국멀티미디어학회논문지
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• 제22권2호
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• pp.186-193
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• 2019

Visible light communication technology is being studied and developed in various ways due to advantages such as high transmission speed, excellent positioning and higher security. However, existing visible light communication systems have difficulties in entering the market because they use special transmitters and receivers. We will overcome the difficulty if we develope a VLC system that uses a conventional LED light as a transmitter and a smartphone camera as a receiver. What matters is that LED lights include a scatter filter to prevent glareness for human eyes, but the existing VLC(Visual Light Communication) method can not be applied. In this paper, we propose a method to encode data with On / Off patterns of LEDs in the lighting with $M{\times}N$ LEDs. We defined parameters like L-off-able and K-seperated to facilitate the recognition of On / Off patterns in the diffused Lights. We conducted experiments using an LED lighting and smart phones to determine the parameter values. Also, the maximum transmission rate of our encoding technique is mathematically presented. Our encoding scheme can be applied to indoor and outdoor positioning applications or settlement of commercial transactions.

• 마이크로전자및패키징학회지
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• 제23권1호
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• pp.29-34
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• 2016

본 연구에서는 생체 영상 이미징을 위한 다채널 필터 모듈 개발 및 특성 평가 연구를 수행하였다. 필터 모듈은 700 nm 및 800 nm 파장대의 근적외선 형광 이미징을 동시에 구현할 수 있도록 제작되었으며, 모듈의 특성 평가를 위해 magnification, exposure, gain의 변수에 따른 signal to back ground ratio (SBR)을 통한 대조영상 평가를 진행하였다. 또한 생체 영상 분석을 위해 신장 및 간의 광학적 특성이 동일한 생체 모사 조직인 phantom을 제작하여 두께에 따른 필터 모듈의 특성 및 광원의 주입량에 따른 특성 연구를 진행하였다. 제작된 필터 모듈은 magnification, exposure, gain의 변화에도 4이상의 SBR 차이를 보이며, kidney phantom 및 liver phantom의 경우 각각 50 mA, 60 mA의 광원 주입량에서 4이상의 SBR 대조 영상을 확인하였다.

• 전자공학회논문지D
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• 제34D권11호
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• pp.64-69
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• 1997

We have shown that the Hough transform filter can be easily obtained by repeatedly recording one line segment pattern holographically by use of rotational multiplexing. With this filter, one can get resutls of the hough transform in the time of light propagation. To demonstrate our method experimentally, the hough transform filter for 18 different rottion angles was recorded, and experimental transform results were compared with simulated ones for a few input patterns. By introducing a compensation process for the non-uniformity of both the input plane wav eand the diffraction efficiency of each hologram. It is possible to get more precise transform results.

• 전자공학회논문지A
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• 제29A권4호
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• pp.14-21
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• 1992

An optical novelty filter is implemented using photorefractive materal(BaTiO$_{3}$) as a recording materal and commercial liquid crystal TV as a spatial light polarization modulator. If a signal beam incident at the proper, the loop and the crossing angle inside th e crystal is formed to get maximum diffraction efficiency and BaTiO$_{3}$ as a self-pumped phase conjugation mirror show that phase conjugate reflectivity was 20 times as much as ordinary polarization if signal beam is extraordinary. In this paper, the stoke's theorem which is a reciprocal theorem for which is a reciprocal theorem for beam path is experimentally proved, and good output images were obtained with optical experiment of novelty filter which is formed by use of Michelson interferometer.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 Ⅳ
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• pp.2032-2035
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• 2003

This paper focused on the possibility of face recognition using Flexible let Point Setting method in Gabor Filter Based Face Recognition. Gabor Filter is very sensible to the Texture variation. Therefore, any little change in the face expression or rotation of posture make recognition rate down significantly. A suggested solution for this problem is the Flexible Jet Point Setting. A significant effect of this method is that the number of Jet Point has been reduced from over 150 to under 30 even though the change of recognition rate between two methods is neglectable, Furthermore a set of feature values which results from a set of Gabor filtering became insensible to face variation such as expression, rotation, and light effect. Retinex Algorithm which has been developed by NASA are used as pre-processing.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 추계학술대회논문집
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• pp.132-137
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• 2003

For the evaluation of acoustic noise of a DLP projector, vibration and sound characteristics of a DLP projector were studied. The acoustic noise of DLP projector could be classified into three categories, that is, the direct noise from a body of rotation, the air-bone noise generated from turbulence or vortex occurred during cooling process and the structural born noise produced by vibrating elements. Cooling fans and color filter wheel which rotates at 9000 rpm are main causes of acoustic noise induced in DLP projector. Since the structure of an optical module in a DLP projector can be excited by the excessive vibration of a color filter wheel, the structural design for anti-vibration should be considered. To make a reduction of overall acoustic noise, the anti-vibration design and the enclosing structure have been studied and applied to a color filter wheel.

• Journal of the Optical Society of Korea
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• 제15권2호
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• pp.202-206
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• 2011

We propose a tunable flat-top bandpass filter to pass light in a customized wavelength band by using long-period fiber gratings (LPFG) structure. The LPFG structure is composed of a core mode blocker in between two LPFGs. The bandpass spectrum of the proposed structure is obtained in overlapped wavelength band of two LPFGs operating on the same modes. To analyze the properties, we introduce a mathematical matrix model for the structure. We theoretically demonstrate flexibility of the flat-top bandpass filter with various bandwidths.

• 한국소음진동공학회논문집
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• 제14권9호
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• pp.861-867
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• 2004

For the evaluation of acoustic noise of a DLP projector, vibration and sound characteristics of a DLP projector were studied. The acoustic noise of DLP projector could be classified into three categories, that is, the direct noise from a body of rotation, the air-bone noise generated from turbulence or vortex occurred during cooling process and the structural born noise produced by vibrating elements. Cooling fans and color filter wheel which rotates at 9000 rpm are main causes of acoustic noise induced in DLP projector. Since the structure of an optical module in a DLP projector can be excited by the excessive vibration of a color filter wheel, the structural design for anti-vibration should be considered. To make a reduction of overall acoustic noise, the anti-vibration design and the enclosing structure have been studied and applied to a color filter wheel.