• Journal of Internet Computing and Services
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• v.11 no.5
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• pp.27-35
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• 2010

In this paper, we propose a method that can compensate the geometric distortions of image caused from an arbitrary nonflat display surface(or wall) under the environment of portable overhead projector without a flat screen. In the proposed method, we first project a grid pattern to an arbitrary nonflat display surface and then derive an equation of straight line that represents the geometry relationship between the distorted grid pattern and the original grid pattern. Next, after determining the proper size of the original grid pattern according to the form of the display surface, we generate a compensation pattern from the derived equation of straight line, which can symmetrically compensate for the distorted image. Finally, we compensate for the geometric distortions of the projected image by segmenting the real image to be projected from portable overhead projector and prewarping it according to the compensation pattern. To evaluate the proposed method, we performed experiments of image compensation on inclined surface, bent surface and curved surface that are frequently occurred in the environment of portable overhead projector without a flat screen. From the experimental results, we found that the proposed method could be very effective in compensating for the general types of the geometric distortions of the projected images.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.181-181
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• 2004

3 차원 형상측정기술(3-D Profile Measurement Method)은 가공품의 치수검사 및 형상측정 등의 공학분야뿐만 아니라 최근에는 의류산업 및 의학산업은 물론 오락산업의 가상현실 구현 등 여러 분야로 점차 사용이 확대되고 있다. 이러한 요구를 만족시킬 수 있는 광학을 바탕으로 한 비접촉 3 차원 형상측정방법(Non-contacting 3-D Profile Measuring Method)은 고속, 고정밀도 측정이 가능하기 때문에 활발히 연구되고 있다. 광학을 이용한 대표적인 3 차원 비접촉 측정방법의 하나인 영사식 무아레는 그림자식 무아레의 단점인 격자의 크기가 측정물체보다 커야 한다는 점과 측정물체와 격자사이의 거리 제한 문제를 해결하였으며, 위상이동법을 사용함으로서, 무아레 무늬 형태의 영향을 받지 않고 측정이 가능해졌다.(중략)

• Korean Journal of Optics and Photonics
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• v.27 no.2
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• pp.67-72
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• 2016

In projection moire topography, the investigation of fringe sensitivity, which means the change rate of fringe order according to object height, is important and necessary to reduce the measurement error of the shape of an object. Using the fringe sensitivity, the determination of the absolute orders of moire fringes can be performed very easily and rapidly. The important parameters in the determination of absolute orders of fringes are the positions of light source and object, and the grating period in projection moire topography. Among these parameters, the fringe sensitivity due to the transverse motion of the light source and the longitudinal motion of the object according to grating periods are analyzed and compared. As a result, whereas the fringe sensitivity in the transverse-motion method increases linearly and gradually as the distance between light source and imaging sensor increases, the fringe sensitivity due to the longitudinal-motion method decreases dramatically as the distance between imaging lens and object increases. In these methods, the fringe sensitivity and its change increase as the grating period increases.

• Proceedings of the Optical Society of Korea Conference
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• 2002.07a
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• pp.202-203
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• 2002

무아레 무늬는 주기적인 두 격자에 비간섭성 광원을 사용하여 얻을 수 있으며, 격자의 모양에 따라 측정 물체의 병진 운동 및 회전 운동 측정이 가능하다. 무아레 기술은 비접촉식 측정 방법으로 실험 장치가 단순하여 물체의 3차원 형상 측정[1], 진동 및 응력 측정[2], 매질의 굴절률 측정[3], 회전각 측정[4] 등과 같은 많은 분야에 응용할 수 있다. 무아레 무늬는 발생 방법에 따라 그림자식과 영사식으로 나뉘며, 영사식은 격자를 측정면에 투영시키는 방법으로 그림자식과 비교하여 격자보다 상대적으로 큰 물체도 측정할 수 있다. (중략)

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.49-52
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• 2001

Moire topography method is a well-known non-contacting 3-D measurement method. Recently, the automatic 3-D measurement by moire topography has been required since the method was frequently applied to the engineering and medical fields. 3-D measurement using projection moire topogrphy is very attractive because of it s high measuring speed and high sensitivity. In this paper, using two-wavelength method of projection moire topography tested to measuring object with the $2\pi$-ambiguity problem. Experimental results prove that the proposed scheme is capable of finding absolute fringe orders, so that the $2\pi$-ambiguity problem can be effectively overcome so as to treat large step discontinuities in measured objects.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.6
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• pp.159-165
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• 2001

Recently Moire and PMP(Phase Measuring Profilometry) are adopted as a practical methodology for non-contact 3-D measurement of free surface. These methods extract the 3-D informations from the images of the object projected with stripe-pattern light. This paper presents a simple projector generating stripe-pattern light using expensive polygon mirror. In this projector, slit-beam is generated with a Laser diode and a rod lens and the laser diode is switched on/off synchronizing with the rotation of the polygon mirror. So its structure is very simple and light-weighted compared to the existent projection methods using several lenses and it is also easy to change the pitch and the phase of the stripe pattern. Experimental results show that the intensity profile of the stripe pattern can be approximated with sinusoidal curve by reducing the pitch of the stripe pattern.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.7 s.172
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• pp.88-93
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• 2005

$Moir\acute{e}$ topography method is a well-known non-contacting 3-D measurement method. Recently, the automatic 3-D measurement by $Moir\acute{e}$ topography has been required, since the method was frequently applied to the engineering and medical fields. The 3-D measurement using projection $Moir\acute{e}$ topography is very attractive because of its high measuring speed and high sensitivity. In this paper, using two-wavelength method of projection $Moir\acute{e}$ topography was tested to measuring object with $2\pi-ambiguity$ problems. The experimental results prove that the proposed scheme is capable of finding absolute fringe orders, so that the $2\pi-ambiguity$ problems can be effectively overcome so as to treat large step discontinuities in measured objects.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.5
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• pp.62-67
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• 2007

A simple dimension measuring method for the measurement of human bust has been developed using projection moire. The 3-D data of a human bust was calculated from the 2dimensional image information obtained by the stripe using projection moire. The creation of 3-D geometric shape by digitizing real objects has been widely investigated in reverse engineering(RE). This procedure generally consists of three basic steps: data capture, data alignment and model reconstruction. In order to achieve a complete model, multiple scans must be taken and aligned.

• Journal of the Korea Convergence Society
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• v.10 no.2
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• pp.7-11
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• 2019

Due to diversification and popularization of devices that use rapid transmission, there are many security issues related to radio waves. As the disturbance and interference of the radio wave can cause a direct inconvenience to a life, it is a very important issue. In this paper, as a means to prevent radio disturbance and interference, the projected image of the reference grid and the deformed grid is obtained by measuring the projected $moir{\acute{e}}$ using the white light source, projecting grid and the light source, and a $moir{\acute{e}}$ pattern is generated with an image processing algorithm by applying a phase diagram algorithm, and generated $moir{\acute{e}}$ pattern phase diagram creates a three-dimensional shape. By making an encrypted token using this measured face shape, the transmission of the information through token ring is determined in order to transmit the horizontal transmission having the dynamic security characteristics which includes authentication strength and caller information, etc. And by confirming the uniqueness of the token and by sending and receiving the horizontal transmission using java serialization and deserialization function, a problem solving method is suggested.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.10a
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• pp.170-175
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• 1999

Noncontact measuring methodology of 3-dimensional profile using CCD camera are very attractive because of it's high measuring speed and its's high sensitivity. Especially, when projecting a grid pattern over the object the captured image have 3 dimensional information of the object. Projection moire extract 3-D information with another grid pattern in front of CCD camera. However phase measuring profilometry(PMP) obtain similar results without additional grid pattern. In this paper, new method for grid pattern generation system by polygonal mirror and Laser Diode. This system is applied the projection moire and the PMP.