• Proceedings of the Membrane Society of Korea Conference
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• 1999.07a
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• pp.79-82
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• 1999

Using Small Angle Light Scattering (SALS), the effect of quench depth on the kinetics of phase separation for ternary solution blends was investigated. The system was composed of two polymers (polystyrene and polybutadiene) and a solvent (toluene). The analyses of the early stage of phase separation were based of the Cahn-Hilliard theory [1,5]. Apparent diffusion coefficients and the fastest mode of fluctuations were evaluated, when quench depth of the system were varied near the critical composition of polymer. In the late stage of phase separation, the domain growth showed a power law with the 1/3 exponent, i.e. $q_m(t)~t^{-1/3}$. For comparison between real images and scattering profiles with time, the image of phase domains with time were obtained by using Laser Confocal Scanning Microscopy (LSCM).

• Proceedings of the KOSOMBE Conference
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• v.1997 no.05
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• pp.379-382
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• 1997

A method for measuring optical properties of biological medium was investigated by using the frequency domain spectroscopy. When amplitude-modulated light with the frequency of several tens up to several hundred MHz propagates through a scattering medium, the phase lag and the amplitude reduction occur. The phase lag depends on the average of optical path lengths. The amplitude reduction with respect to the radial distance is influenced by the penetration depth. The mean of optical path length and penetration depth are related to optical coefficients. The phase lag and the amplitude reduction were measured based on the heterodyne detection method. The experimental data were fitted with the theoretical curves derived from diffusion theory and the absorption and scattering coefficients were calculated.

• Macromolecular Research
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• v.10 no.1
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• pp.2-12
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• 2002

The small-angle X-ray scattering (SAXS) beamline BL4C1 at the 2.5 GeV storage ring of the Pohang Accelerator Laboratory (PAL) has been in its first you of operation since August 2000. During this first stage it could meet the basic requirements of the rapidly growing domestic SAXS user community, which has been carrying out measurements mainly on various polymer systems. The X-ray source is a bending magnet which produces white radiation with a critical energy of 5.5 keV. A synthetic double multilayer monochromator selects quasi-monochromatic radiation with a bandwidth of ca. 1.5%. This relatively low degree of monochromatization is sufficient for most SAXS measurements and allows a considerably higher flux at the sample as compared to monochromators using single crystals. Higher harmonics from the monochromator are rejected by reflection from a flat mirror, and a slit system is installed for collimation. A charge-coupled device (CCD) system, two one-dimensional photodiode arrays (PDA) and imaging plates (IP) are available its detectors. The overall performance of the beamline optics and of the detector systems has been checked using various standard samples. While the CCD and PDA detectors are well-suited for diffraction measurements, they give unsatisfactory data from weakly scattering samples, due to their high intrinsic noise. By using the IP system smooth scattering curves could be obtained in a wide dynamic range. In the second stage, stating from August 2001, the beamline will be upgraded with additional slits, focusing optics and gas-filled proportional detectors.

• Nuclear Engineering and Technology
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• v.52 no.6
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• pp.1277-1281
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• 2020

A novel ceramic Gas Electron Multiplier (GEM) has been developed to meet the demand of high counting rate for the neutron detection which is an alternative to ³He-based detector at China Spallation Neutron Source (CSNS). An experiment was performed to measure the neutron transmittance of ceramic-GEM and FR4-GEM at the small angle neutron scattering (SANS) instrument. The result showed the ceramic-GEM has higher transmittance and less self-scattering especially for cold neutrons. One single ceramic GEM could give a gain of 10²-10⁴ in the mixture gas of Ar and CO₂ (90%:10%) and its energy resolution was about 27.7% by using ⁵⁵Fe X ray of 5.9 keV. A prototype has been developed in order to investigate the performances of the ceramic GEM-based neutron detector. Several neutron beam tests, including detection efficiency, spatial resolution, two-dimensional imaging, and wavelength spectrum, were carried out at CSNS and China Mianyang Research Reactor (CMRR). The results show that the ceramic GEM-based neutron detector is a good candidate to measure the high intensity neutrons.

• Polymer Science and Technology
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• v.25 no.4
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• pp.322-328
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• 2014

• Proceedings of the Korean Nuclear Society Conference
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• 2004.10a
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• pp.1241-1242
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• 2004

• Polymer Science and Technology
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• v.23 no.5
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• pp.541-546
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• 2012

• Proceedings of the Korean Vacuum Society Conference
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• 1998.02a
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• pp.101-102
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• 1998

• Journal of the Korea Institute of Military Science and Technology
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• v.19 no.5
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• pp.590-597
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• 2016

We designed the multiple scattering points generation system to simulate an actual situation of target signal for high range resolution radar system. This provides replicating the target signals and controlling the status of target signals for radar system. This is composed transmit antenna and multi target generator. Transmit antenna is waveguide array antenna and multi target generator has signal distribution module and control & power module. Multi target generator is able to provide the high isolation and variable output power. Moreover, in order to monitor all output signals of the multi target generator, the flows of signals are programed in control & power module. The performance is demonstrated using experimented results of high range resolution radar.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.26 no.2
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• pp.139-146
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• 2016

Objectives: This study aimed to confirm the optimal processing conditions of the asbestos stabilizer by considering various actual environments at the time of stabilization treatment of the ceiling materials containing asbestos with asbestos stabilizer. Methods: The anti-scattering performances of the asbestos stabilizer were confirmed by considering the method and quantity of the asbestos stabilizer treated, comparing the loss weight by measuring the weight of ceiling materials prior to and after having treated 30, 50, 100, 200, and 400 of stabilizer using the brush and spray. The effects of backside dust and steel frame structure on the performances of the stabilizer was also confirmed by comparing samples with and without the dust on the rear surface removed by wiping the ceiling material specimens and the blinding treatment simulated by using tape. Results: The asbestos stabilization treatment using the brush method in comparison with the use of a spray has reduced stabilizer loss, resulting in better anti-scattering performance. In addition, the stabilizer loss is increased with increasing treatment quantity; as a result, treating a larger quantity of stabilizer does not improve the performance. For the conditions related to ceiling materials, the anti-scattering performance is enhanced by removing the backside dust and spreading the stabilizer evenly on the masking portion by steel frame structures. Conclusions: Based on these results, it is determined that the appropriate choice of the tool used for the treatment of the asbestos stabilizer and the appropriate quantity of asbestos stabilizer were needed at the time of actual stabilization processing of the ceiling materials containing asbestos. Moreover, this study confirmed that preliminary processing and verification of the structure at which the ceiling materials are installed can enhance the effectiveness of prevention of the scattering of asbestos into the air.