• 한국음향학회지
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• 제16권3호
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• pp.51-56
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• 1997

본 논문에서는 SLAM(Scanning Laser Acoustic Microscope) 시스템을 이용하여 고체 내부에 발생한 크랙의 깊이를 측정하는 방법을 연구하였다. SLAM 시스템은 초음파의 투과계수에 따른 그림자 영상을 재생시키므로 크랙 깊이에 대한 정확한 측정방법이 요구된다. 이를 위하여 시료에 초음파를 사각으로 입사시켜 얻은 SLAM 영상의 그림자영역과 시료내의 초음파 모드 변환에 대한 기하학적 구조를 이용하여 크랙의 깊이를 측정할 수 있는 방법을 제안하고 실험을 통하여 확인하였다. 실험을 위하여 알루미늄에 서로 다른 깊이로 수직형 라인-크랙의 결함을 갖는 시료를 가공하였고 시료에 초음파를 사각 입사시키기 위하여 20$^{\circ}$ 각도로 웨지를 제작하였다. 실험 결과, 크랙의 깊이가 증가할수록 SLAM 영상의 그림자 영역이 비례적으로 증가함을 보였고, 결함의 깊이에 대한 측정치와 실제치를 비교한 결과 약 6% 이하의 측정오차를 보였다.

• Nuclear Engineering and Technology
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• 제44권1호
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• pp.43-52
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• 2012

To compute a permeability coefficient along a rough fracture that takes into account the fracture geometry, this study performed detailed measurements of fracture roughness using a confocal laser scanning microscope, a quantitative analysis of roughness using a spectral analysis, and a homogenization analysis to calculate the permeability coefficient on the microand macro-scale. The homogenization analysis is a type of perturbation theory that characterizes the behavior of microscopically inhomogeneous material with a periodic boundary condition in the microstructure. Therefore, it is possible to analyze accurate permeability characteristics that are represented by the local effect of the facture geometry. The Cpermeability coefficients that are calculated using the homogenization analysis for each rough fracture model exhibit an irregular distribution and do not follow the relationship of the cubic law. This distribution suggests that the permeability characteristics strongly depend on the geometric conditions of the fractures, such as the roughness and the aperture variation. The homogenization analysis may allow us to produce more accurate results than are possible with the preexisting equations for calculating permeability.

• Nuclear Engineering and Technology
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• 제45권1호
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• pp.53-60
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• 2013

Bentonite is generally used as a buffer material in high-level radioactive waste disposal facilities and consists of 50% quartz by weight. Quartz strongly affects the behavior of bentonite over very long periods. For this reason, quartz dissolution experiment was performed under high-pressure and high-alkalinity conditions based on the conditions found in a high-level radioactive waste disposal facility located deep underground. In this study, two quartz dissolution experiments were conducted on 1) quartz beads under low-pressure and high-alkalinity conditions and 2) a single quartz crystal under high-pressure and high-alkalinity conditions. Following the experiments, a confocal laser scanning microscope (CLSM) was used to observe the surfaces of experimental samples. Numerical analyses using the finite element method (FEM) were also performed to quantify the deformation of contact area. Quartz dissolution was observed in both experiments. This deformation was due to a concentrated compressive stress field, as indicated by the quartz deformation of the contact area through the FEM analysis. According to the numerical results, a high compressive stress field acted upon the neighboring contact area, which showed a rapid dissolution rate compared to other areas of the sample.

• 한국가축번식학회지
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• 제20권3호
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• pp.343-351
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• 1996

본 연구의 목적은 돼지난자의 체외성숙, 수정 및 단위발생시 일어나는 표층과립의 분포를 살펴보고, 그것들의 역할을 규명해 보고자 실시하였다. 난자의 표층과립은 형광염색을 실시한 후 laser scanning confocal microscope를 이용하여 관찰하거나 transmission electron microscope를 사용하여 관찰하였다. Germinal vesicle 단계의 돼지난자에서는 표층과립은 난자피질에 비교적 두꺼운 형태로 발견되었는데, germinal vesicle breakdown이 일어난 직후 피질 부근으로 표층과립의 움직임이 관찰되었다. Microfilaments의 중합화를 방해하는 cytochalasin B를 처리하였을 때 표층과립의 움직임은 관찰되지 않았다. 무 처리군의 수정 및 단위발생을 유도한 난자에서는 표층과립 내용물들이 위란강내에 균질하게 관찰되었으나, cytochalasin B를 처리한 난자에서는 비정상적인 cortical granule의 움직임을 관장하고 이러한 움직임이 수정시 다정자 침입을 막고 표층과립 반응에 영향을 미치는 것으로 사료된다.

• Journal of the Optical Society of Korea
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• 제18권1호
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• pp.50-54
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• 2014

In this paper we studied the laser-induced crater depth, mass, and emission spectra of laser-ablated high-density polyethylene (HDPE) polymer using the laser-induced plasma spectroscopy (LIPS) technique. This study was performed using a Nd:YAG laser with 100 mJ energy and 7 ns pulse width, focused normal to the surface of the sample. The nanoscale change in ablated depth versus number of laser pulses was studied. By using scanning electron microscope (SEM) images, the crater depth and ablated mass were estimated. The LIPS spectral intensities were observed for major and minor elements with depth. The comparison between the LIPS results and SEM images showed that LIPS could be used to estimate the crater depth, which is of interest for some applications such as thin-film lithography measurements and online measurements of thickness in film deposition techniques.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 추계학술대회 논문집 학회본부
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• pp.251-253
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• 1996

High temperature superconducting (HTS) target has been irradiated by excimer laser beam. The surface of HTS target has been changed and showed the formation of cones. The laser ablated HTS target surface has been systematically studied using a scanning electron microscope. A KrF excimer laser with a wavelength of 248 nm was used to ablate the HTS YBCO target. The size of laser beam focused on the target showed a rectangular shape of $9.7{\times}2\;mm^2$. The image of SEM shows the difference between the shapes of cones fanned at the boundary and at the center of the ablated area after 1,000 laser pulses.

• 대한치과기공학회지
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• 제35권4호
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• pp.281-286
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• 2013

Purpose: Surface modification is important techniques in modern dental and orthopedic implants. This study was performed to try embedding of bioactive materials in porous Ti implants. Methods: Porous Ti implant samples were fabricated by sintering of spherical Ti powders in a high vacuum furnace. It's diameter and height were 4mm and 20mm. Embedding process was used to suction and vacuum chamber. Loading properties of porous Ti implants were evaluated by scanning electron microscope(SEM), confocal laser scanning microscope(CLSM), and UV-Vis-NIR spectrophotometer. Results: Internal pore structure was formed fully open pore. Average pore size and porosity were $10.253{\mu}m$ and 17.506%. Conclusion: Porous Ti implant was fabricated successfully by sintering method. Particles are necking strongly each other and others portions were vacancy. This porous structure can be embedded to bioactive materials. Therefore bioactive materials will be able to embedding to porous Ti implants. Bioactive materials embedding in the porous Ti implant will induced new bone faster.

• 한국가시화정보학회지
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• 제11권2호
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• pp.41-45
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• 2013

Two-photon microscopy (TPM) is minimally-invasive 3D fluorescence microscopy based on nonlinear excitation, and TPM can visualize cellular structures based on auto-fluorescence. Line-scanning TPM is one of high-speed TPM methods without sacrificing the image resolution by using spatial and temporal focusing. In this paper, we developed line-scanning TPM based on spatial and temporal focusing for auto-fluorescence imaging by exciting the tryptophan. Laser source for this system was an optical parametric oscillator (OPO) and it made near 570 nm femtosecond pulse laser. It had 200fs pulse width and 1.72 nm bandwidth, so that the achievable depth resolution was 2.41um and field of view (FOV) is 10.8um. From the characterization, our system has 3.0 um depth resolution and 12.3 um FOV. We visualized fixed leukocyte cell sample and compared with point scanning system.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.1539-1542
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• 2005

Self-assembled monolayers (SAMs) formed by the adsorption of alkanethiols, $HS(CH_2)_nX$, where X is an organic functional group, onto gold surfaces have attracted widespread interest as templates for the fabrication of molecular and biomolecular microstructures. Previously photopatterning has been thought of as being restricted to the micron scale, because of the wellknown diffraction limit. So, we have explored a novel approach to nanofabrication by utilizing a femtosecond laser coupled to a near-field scanning optical microscope (NSOM).

• 펄프종이기술
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• 제31권3호
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• pp.54-59
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• 1999

This study was to quantify fiber distributions in thickness direction of kenaf handsheets as a fiber distribution index (FDI) and to analyze the relationship between FDI and the handsheet properties. The images of fiber distribution in z-direction were obtained by Confocal Laser Scanning Microscope (CLSM) and analyzed by image analysis technique. The proposed FDI had a good correlation with high R2 vlaues with various properties of paper, such as apparent density, scattering coefficient , burst index, tear index, tensile index, and folding endurance. The proposed FDI was shown as a good index to quantify paper properties.