• 한국정보통신학회논문지
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• 제21권12호
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• pp.2285-2290
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• 2017

최근 산업의 여러 분야에서 자동화 시스템이 발전함에 따라 3D 측정에 의한 물체의 높이 검사의 필요성이 점차 대두되고 있다. 여러 3D 측정 방법 중에서 본 논문에서 다루는 방법은 위상 측정법으로, 위상 측정법이란 프린지 패턴의 위상값을 이용하여 물체의 높이를 구하는 방법이다. 위상 측정법은 연산량이 많이 필요한 알고리즘이기 때문에 이를 효율적으로 해결할 방법이 필요하다. 본 논문에서는 이를 위해 NVIDIA에서 나온 CUDA를 사용할 것을 제안했다. 또 CUDA에서 제공하는 Pinned memory와 Stream을 사용할 것을 제안하였다. 이를 통해 정확도를 유지하면서 측정 속도는 크게 향상시킬 수 있었고 실험을 통해 성능을 입증하였다.

• 대한조선학회지
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• 제3권1호
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• pp.11-18
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• 1966

In a polarized light field, triangular plate bracket specimen of CR-39 with lightening hole were subjected to tension. The variables of the models used in the experiment were taken in the range of length-depth $ratio=0.583{\sim}1.715$, eccentricity of lightening hole from the geometrical center of $bracket=-1/4"{\sim}+1/4"$, and the lightening hole $diameter=1/2"{\sim}2"$. The isoclinics were drawn and from those the stress trajectories were constructed. Then the distributions of boundary stress around the lightening holes were determined from the isochromatic fringe pattern. The conclusions reached in this investigation are as follows: 1. Maximum stresses of the hole boundary are gradually increased when the diameter of the lightning hole increase. 2. Maximum stresses of the lightning hole boundary are decreased gradually when the eccentricity of the lightning hole from the geometrical center of the bracket to the farther side from the free end. 3. If the minimum distances from the free end of the brackets to the lightening hole boundaries are equal, the variation of the maximum stresses are in a small range for the change of lightening hole diameter and its location. 4. When the length-depth ratios are smaller than 0.8, the maximum stresses increase steeply. In the range of $0.8{\sim}1.2$ maximum stresses increase gradually and thereafter increase rapidly when the length-depth ratio of the bracket increase for the same diameter of a lightening hole.

• Bulletin of the Korean Chemical Society
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• 제29권10호
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• pp.1969-1972
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• 2008

In this study, horse spleen apoferritins were induced to form biominerals using up to 3000 Fe atoms per protein molecule. The morphology and crystallinity of the nanometer-sized biominerals formed in the ferritins were then analyzed using field emission-energy filtering-transmission electron microscopy (FE-TEM). The ferritins were found to have reconstitution yields of 60-70% in the experiments. The mean core size of the ferritins varied somewhat with protein concentrations, indicating that crystal growth in ferritins could be controlled via protein concentrations. The core mineral size increased with the amount of Fe used. Lattice fringes of the core, associated with good crystallinity, were found in all samples. The lattice fringe images of a single domain ferrihydrite mineral appeared frequently in the (011) planes (d-spacing of 0.246 nm) under [100] zone axis in all samples of this study. In addition, the lattice image occasionally revealed fringes corresponding to the (100) planes (d = 0.254 nm) from the [001] zone axis, indicating the characteristic pattern of hexagonal crystal lattice. Diffraction patterns in the minerals identified as ferrihydrite were fitted well into the space group of $P3_{1c}$.

• 대한기계학회논문집
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• 제12권3호
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• pp.566-574
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• 1988

본 연구에서는 LDV의 수광계를 비임의 진행방향에 수직한 방향으로 위치시켜 분무액적에 의한 반사 산란성분을 수광하여 검출되는 신호의 가시도에 의해 액적크기 를 측정함과 동시에 도플러변화 주파수로부터 속도를 측정하고, 이 방법의 신뢰도를 충돌식 포진법에 의하여 측정한 결과와 비교하므로써 평가하여, 관측각 90˚의 측방 산란형 LDV에 의한 분무액적의 크기와 속도의 동시측정에 관한 유용성을 살펴보고자 한다.

• 한국생산제조학회지
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• 제9권3호
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• pp.130-135
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• 2000

In this study the vibration behavior of the stiffened double cylinder was experimently analyzed. Due to the complex structure of the double cylinder the outside cylinder frequency responses to the exciting forces applied on various posi-tions were analyzed by using spectrum analyzer in conjunction with an accelerometer and the natural frequencies were obtained. The technique of time-averaged holographic interferometry is applied to study the vibration characteristics of outside cylinder with stiffening T frame. The experimental data showed that the T frame had salient effect of damping on the testing structure at most of resonances. however the experimental results also revealed interesting phenomenon. At some particular frequencies the T frame. The experimental data showed that the T frame had salient effect of damping on the testing structure at most of resonances. However the experimental results also revealed interesting phenomenon. At some particular frequencies the T frame seemed to behave as a transmitter. In addition it has been successfully demon-started that optical method such as holographic interferometry is well suited for the identification of mode shapes. They can give us a whole-field non-contact measurement instead of the point-wise measurement by accelerometer in classical modal testing.

• 대한기계학회논문집B
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• 제25권11호
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• pp.1624-1631
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• 2001

Variations of temperature field in a Hele-Shaw convection cell (HSC) were measured using a holographic interferometry with varying Rayleigh number. Experimental results show a steady flow pattern at low Rayleigh numbers and a time-dependent periodic flow at high Rayleigh numbers. Especially, the period of oscillation at Ra = 6.35 $\times$ 10$^{6}$ was 62 seconds. Two different measurement methods of holographic interferometry, double-exposure method and real-time method, were employed to measure the temperature field variations of HSC convective flow. In the double-exposure method, unwanted waves can be eliminated and reconstruction images are clear, but transient flow structure cannot be observed clearly. On the other hand, transient flow can be observed and reconstructed well using the real-time method. However, the fringe patterns reconstructed by the real-time method contain more noise, compared with the double-exposure method. The two holographic interferometer techniques employed complementary in this study were proved to be useful fur analyzing the temperature field variations of unsteady thermal fluid flows.

• 대한치과교정학회지
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• 제16권2호
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• pp.43-51
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• 1986

The highly accurate laser holographic interferemotry method was used to determine in what way low-magnitude forces during maxillary expansion are transmitted to the entire maxillary complex and its surrounding structures. The experiments were carried out on a dryed human skull which had a perfectly preserved, normally aligned maxillary dental arch and intact alveolar process. The skull was fixed within a constructed metal frame which ensured maximal stability of the object. The optical equipment and the object were mounted on antivibration table. Interferograms were taken on the lateral and frontal sides of the maxillary complex, using the 10mW He-Ne laser and the double-exposure method. Analysis of the fringe pattern on the recorded object surface was performed by graphically determining the deformation curves related to the bony surface in selected horizontal and vertical planes. On the basis of this study, the following conclusions can be drawn: 1. The density of the interference fringes was gradually increased with the degree of expansion force. 2. Mechanical reactions on the maxillary complex, circummaxillary sutures, and surrounding bones were clearly visible, even with the lowest loading degree. 3. The amount of bone displacement was greater in application of the force after $90^{\circ}$ turn than in initial application of the same force. 4. The direction of interference fringes on the bony surface was similar at all loading degrees.

• 한국전기전자재료학회논문지
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• 제17권9호
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• pp.994-1000
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• 2004

We studied the characteristics of annular phase gratings as spatial frequency filters. We first calculated the Fraunhofer diffraction patterns of annular gratings and then got the modulation transfer function (MTF) from the zeroth order Hankel transform of the intensity distribution function. Binaryphase annular grating shows higher diffraction efficiency than binary phase rectangular grating. But the MTF decreases linearly in the low-frequency region as that of rectangular grating does. The diffraction pattern of 4-phase annular grating is similar to that of 2-phase grating and hence MTFs of the two are much alike. For 8-phase annular grating, the 7th order diffracted beam is the lowest one next to the first. Consequently, the diffraction efficiency is very high and the MTF graph is curved upward. The diffracted beams except the first order are negligible and hence the MTF characteristics are more improved in the case of 16-phase grating. But the degree of improvement becomes lowered c(Impaled with 8-phase grating. We made a 16-phase annular grating and measured its MTF. The experimental result agrees well with the calculated one.

• 통합자연과학논문집
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• 제3권2호
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• pp.78-83
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• 2010

DBR/Host dual porous silicons containing DBR and host structure were prepared and their optical properties were characterized using Ocean Optics spectrometer. In this dual porous silicon, single porous silicon layer was used as host layer for possible biomolecule and drug materials and DBR porous silicon layer was used for signal transduction due to the recognition of molecules. Optical reflection spectrum of dual porous silicon displayed only DBR reflection but Fabry-Perot fringe pattern. DBR reflection band of dual porous silicon shifted to the shorter wavelength as the etching time of host layer increased. Cross-sectional FE-SEM image of dual porous silicon displayed a thickness of about 20 micrometer for DBR porous silicon layer. Developed etching technology could be useful to prepare DBR porous silicon which exhibited specific reflection resonance at the required wavelength and to provide an label-free biosensors and drug delivery materials.

• 대한기계학회논문집
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• 제12권1호
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• pp.28-35
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• 1988

본 연구는 이중벽용기에서 볼 수 있는 환상공간에 관한 자연대류 연구로서 용기속에 들어있는 유체의 열차폐를 위한 최적의 가스두께를 측정하기 위하여 필요한 지식을 얻기위한 열전달 연구이다.