• Proceedings of the Korean Society of Precision Engineering Conference
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.226-230
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• 2001

Electronic Speckle Pattern Interferometry (ESPI) has been recently developed and widely used because it has advantage to be able to measure surface deformations of engineering components and materials in industrial areas with non-contact. The spekle patterns to be formed with interference phenomena of scattering phenomena measure the out-of-plane deformations, together with the use of digital image equipment to process the informations included in the speckle patterns and the display consequent interferogram on a computer monitor. In this study, the experimental results of a canti-levered plate using ESPI were compared with those obtained from the simple beam theory. The ESPI results of the canti-levered plate analyzed by 4-step phase shifting method are close to the theoretical expectation. Also, out-0of-plane displacements of a spot welded canti-levered plate were measured by ESPI with 4-step phase shifting technique. The phase map of the spot welded canti-levered plate is quite different from that of the canti-levered plate without spot welding.

• Journal of the Korean Society for Precision Engineering
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• 제30권7호
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• pp.702-708
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• 2013

The white-light scanning interferometer (WSI) is an effective optical measurement system for high-precision industries (e.g., flat-panel display and electronics packaging manufacturers) and semiconductor manufacturing industries. Its major disadvantages include a slow image-capturing speed for interferogram acquisition and a high computational cost for peak-detection on the acquired interferogram. Here, a WSI system is proposed for the semiconductor inspection process. The new imaging acquisition technique uses an 'on-the-fly' imaging system. During the vertical scanning motion of the WSI, interference fringe images are sequentially acquired at a series of pre-defined lens positions, without conventional stepwise motions. To reduce the calculation time, a parallel computing method is used to link multiple personal computers (PCs). Experiments were performed to evaluate the proposed high-speed WSI system.

• Journal of ILASS-Korea
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• 제2권4호
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• pp.29-35
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• 1997

Liquid film thickness is measured by $moir\acute{e}$ topography which monitored liquid surface. $Moir\acute{e}$ fringe measurement techniques share the inherent simplicity found in optical interferometric techniques have the advantage of use over a greater range of displacement. $Moir\acute{e}$ fringe are the geometric interference patterns observed when two dense line grating are superposed. Light transmitted through a fixed line grating is deviated by the liquid film surface, producing a distored image of the grating. The $moir\acute{e}$ fringe produced by projection of this optically distored grating onto a second stationary grating permit visualization of the liquid surface and measurement of the liquid film thickness. This study measured the small amplitude of liquid film thickness to the $moir\acute{e}$ fringe pattern produced when spherical metal was dropped glycerin put)1 And the measurement of liquid film thickness flowing down an inclined plate are required to calculate the liquid slope in a position.

• Journal of the Optical Society of Korea
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• 제11권1호
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• pp.18-25
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• 2007

We present an ultrahigh-resolution full-field optical coherence tomography (FF-OCT) implemented with a white-light interference microscope and a detector array as an alternative OCT technique. The use of detector array allows the capture of two-dimensional en-face images in parallel without taking any lateral scanning process. The phase shifting interferometric technique with the sinusoidal phase modulation (SPM) is utilized to get the demodulated OCT images. The configuration of the system and the resolution of the obtained image are presented. The topographic images, taken with the implemented system, of a coin, an integrated circuit chip, and the tomographic images of an onion epithelium are demonstrated also. Axial and lateral spatial resolution of ${\sim}1.0{\mu}m$ and ${\sim}2.0{\mu}m$ are achieved with the system respectively.

• Journal of the Korean Society for Precision Engineering
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• 제9권4호
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• pp.90-99
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• 1992

In resent year Laser Speckle and its development have enabled surface deformation of engineering components and materials to be interferometrically examined. Laser Speckle- Pettern Interferometry Method is a very useful method for measuring In-plane components of displacement. In measuring thermal expansion coefficient, the various problems generated were established, and the measuring limitation examined. Metarial INCONEL 601 was used in experiments. Specimen was heated to the high temperature(100$0^{\circ}C$) by diong current to the direct two specimen. Then, those problems appear to the influence of back-ground radiation by the heated specimen, the influence by air turbulence, the oxidation of specimen. The color monitor and interference filter prevented the back-ground radiation by rad heat. The oxidation occuring in specimen itself was not generated by the being acid-proof excellence of material INCONEL 601. Yet, in this experiments, the serious problems are the oxidation of specimen and influence by air turbulence. By more reserching these problems forward, it is helpful that the thermal expansion coefficient of many materials is directly measured under high temperature.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 한국방송공학회 2015년도 추계학술대회
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• pp.71-73
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• 2015

In this paper, we propose the Real-Time Free Viewpoint TV System with multiple Microsoft Kinects and CUDA of NVidia GPGPU library. It generates a virtual view between two views by using color and depth image acquired by Kinect in real time. In order to reduce complexity of coordinate transformations and nearest neighbor method for hole filling caused by IR pattern interference, we parallelize this process using CUDA. Finally, it is observed that CUDA based system generates more frames than using CPU based system in the same time.

• Transactions of the Korean Society of Mechanical Engineers B
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• 제25권3호
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• pp.397-404
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• 2001

The behavior of unsteady wake vortices for the two-dimensional flat plate is simulated by a discrete vortex method. The flat plates and their wakes are represented by vortex sheets. The vortex sheets are replaced with discrete vortices. The freely deforming wake sheets are computed as a part of solution and the ground effect is included by a image method. In order to predict wake shapes accurately and to model closely coupled aerodynamic interference, a vortex core model and a vortex core addition scheme are used. The simulated wake shapes convecting behind the plates in unsteady motion are compared to a flow visualization result and other numerical results. The present results agree well with them. The present method is also applied to the aerodynamic analysis of flat plates in tandem configuration in ground effect.

• Journal of Magnetics
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• 제14권3호
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• pp.124-128
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• 2009

Magnetic nanoparticles were synthesized by using the sonochemical method with oleic acid as a surfactant. The average size of the magnetite nanoparticles was controlled by varying the ratio R=[$H_2O$]/[surfactant] in the range of 2 to 9 nm. To prepare chitosan-coated magnetite nanoparticles, chitosan solution was added to a magnetite colloid suspension under ultrasonication at room temperature for 20 min. The chitosan-coated magnetite nanoparticles were characterized by several techniques. Atomic force microscopy (AFM) was used to image the chitosan-coated nanoparticles. Magnetic hysteresis measurement was performed by using a superconducting quantum interference device (SQUID) magnetometer to investigate the magnetic properties of the magnetite nanoparticles and the chitosan-coated magnetite nanoparticles. The SQUID measurements revealed the superparamagnetism of both nanoparticles. The T1- and T2-weighted MR images of these chitosan-coated magnetite colloidal suspensions were obtained with a 4.7 T magnetic resonance imaging (MRI) system. The chitosancoated magnetite colloidal suspensions exhibited enhanced MRI contrasts in vitro.

• The Journal of Korean Institute of Communications and Information Sciences
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• 제25권9A호
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• pp.1306-1312
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• 2000

The quality loss of a X-band transmitter has been derived by means of MC simulation. The transmitter as a payload of LEO(Low Earth Orbit) satellite is capable of the down transmission the image data of hundreds Mbps generated from the Electro-Optical Instrument in real time. The parameters such as data asymmetry amplitude unbalance,phase unbalance, wave shaping and channel interference are included in the quality loss simulation Assuming that normally distributed gaussian noise is simply added to the channel, the quality loss of 0.7 dB has been obtained through this simulation based on a 95% confidence interval. The obtained quality loss can be applied to the link budgets as an additional loss item.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 한국방송공학회 2015년도 하계학술대회
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• pp.122-124
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• 2015

This paper provides the design and implementation of Free Viewpoint TV System with multiple Microsoft Kinects. It generates a virtual view between two views by manipulating texture and depth image captured by Kinects in real-time. In order to avoid this, we propose the hole-filling scheme using Nearest neighbor and inpainting. As a result, holes generated by interference are filled with new depth values calculated by their neighbors. However, the depth values are not accurate, but are similar with their neighbors. And depending on the frequency of running a Nearest Neighbor method, we can see that edge's border would be shifted inner or outer of the object.