• Proceedings of the Optical Society of Korea Conference
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• 2005.02a
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• pp.50-51
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• 2005

• Proceedings of the Optical Society of Korea Conference
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• 2007.02a
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• pp.225-226
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• 2007

• Proceedings of the Optical Society of Korea Conference
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• 2006.07a
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• pp.231-232
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• 2006

• Proceedings of the Korean Society of Rheology Conference
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• 2001.06a
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• pp.41-44
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• 2001

• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.5
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• pp.311-317
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• 2009

Due to extremely small device size and velocity scale, mixing in microchannel take place very slowly by way of molecular diffusion transport. Mixing enhancement becomes a central issue in microfluidics for biomedical and chemical applications. In this work, The optimization results and validation through experiment and fabrication. In this efficient micromixer design, it is essential to evaluate mixing efficiency with good precision. Mixing efficiency for Y-channel micromixer is measured by fluorescence intensity using LIF(Laser Induced Fluorescence) Confocal Microscope. The Y-channel micromixers are fabricated with polydimethylsiloxane(PDMS). Nile Blue A is injected into the micromixer as a fluorescence dye for measuring of fluorescence intensity by He/Ne laser. Throughout the experiments and computer simulation, accurate mixing efficiency evaluation process for a PDMS Y-channel micromixer is established.

• The Journal of Engineering Geology
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• v.12 no.4
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• pp.405-419
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• 2002

Fracture roughness of rock specimens is observed by a new confocal laser scanning microscope (CLSM; Olympus OLS1100). The wave length of laser is 488 nm, and the laser scanning is managed by a light polarization method using two galvano-meter scanner mirrors. The function of laser reflection auto-focusing enables us to measure line data fast and precisely. The system improves resolution in the light axis (namely z) direction because of the confocal optics. Using the CLSM, it is Possible to measure a specimen of the size up to $10{\;}{\times}{\;}10{\;}cm$ which is fixed on a specially designed stage. A sampling is managed in a spacing $2.5{\;}\mu\textrm{m}$ along x and y directions. The highest measurement resolution of z direction is $10{\;}\mu\textrm{m}$, which is more accurate than other methods. Core specimens of coarse and fine grained granite are provided. Fractures are artificially maneuvered by a Brazilian test method. Measurements are performed along three scan lines on each fracture surface. The measured data are represented as 2-D and 3-D digital images showing detailed features of roughness. Line profiles of the coarse granites represent more frequent change of undulation than those of the fine granite. Spectral analyses by the fast Fourier transform (FFT) are performed to characterize the roughness data quantitatively and to identify influential frequency of roughness. The FFT results suggest that a specimen loaded by large and low frequency energy tends to have high values of undulation change and large wave length of fracture roughness.

• Nuclear Engineering and Technology
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• v.44 no.1
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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.

• Restorative Dentistry and Endodontics
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• v.27 no.1
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• pp.12-15
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• 2002

The first purpose of present study was to compare the anticariogenic effect of compomer, resin modified glass ionomer cement and composite (RMGIC). The second purpose was to evaluate the recently introduced methods, which use confocal scanning micro-scope, in detecting initial caries around restoration. 2$\times$4$\times$1.5mm cavities were prepared from the recently extracted 50 human teeth on the buccal or lingual surface. The prepared teeth were randomly devided into 5 groups and restored with each filling material. Group 1: Dyract AP, Group 2: compoglass F, Group 3: F2000, Group 4: Z100. Group 5:Fuji II LC. The teeth were stored for 30 days in the distilled water, then stored in the buffer solution for artificial caries development: pH 4.3, lactic acid 100 mM, calcium 16 mM, phosphate 8mM, sodium azide 3mM. Then, the samples were sectioned longitudinally and examined with confical scanning microscope. The results showed that the use of compomer and resin modified glass ionomer cement showed caries inhibition zone whereas the composite did not. There was no difference in the width of caries inhibition zone between compomers and RMGIC. The confocal scanning microscope was useful in detecting initial caries around restoration.

• Nuclear Engineering and Technology
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• v.45 no.1
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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.

• Journal of the Optical Society of Korea
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• v.18 no.5
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• pp.598-604
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• 2014

A polarization fluorescence correlation spectroscopy system based on a confocal microscope was built to study the rotational and translational diffusion of CdSe/CdS quantum rods (Q-rods), with the same and different polarization states between the polarizer and the analyzer (i.e. the XXX and XYY states). The rotational diffusion amplitude showed the dependences on polarization of $0.75{\pm}0.05$ in the XXX state and $0.26{\pm}0.03$ in the XYY state, when the translational diffusion amplitude was 1. The diffusion coefficients of the Q-rods were found based on their translational and rotational diffusion times in the two polarization states, in solutions with viscosity ranging from 0.9 to 6.9 cP. The translational and rotational diffusion coefficients ranged from $1.5{\times}10^{-11}$ to $2.6{\times}10^{-12}m^2s^{-1}$ and from $2.9{\times}10^5$ to $5.6{\times}10^4s^{-1}$, respectively.