• Journal of the Korean Chemical Society
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• v.35 no.5
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• pp.539-544
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• 1991

A method to determine the thickness of silicone resin film on zinc eletroplated steel using X-ray compton scattering was investigated. On the basis of the fact that compton scattering process predominates over photoelectric absorption for the light elements such as C, H, O and Si, the compton scattered line of RhK$_{\alpha}$ was used to determine the thickness of silicone resin. In this method, the standard calibration curve for thickness determination of silicone resin film was found to be linear in the range of 0.2~5.0 ${mu}$m film thickness. The analytical results agreed well with those obtained by the gravimetric method and the accuracy was found to be 0.22 ${mu}$m.

• Journal of Astronomy and Space Sciences
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• v.2 no.2
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• pp.101-115
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• 1985

Using Brandt model the mess distribution of the late type spiral galaxy NGC 6946 was derived, and the total mass was reestimated to understand the M/L ratio of this galaxy. Two kinds of the rotation curve with shape parameter n=1 and 3.3 were examined. The following are the main results; (1) The total masses of NGC 6946 are $3.1\times$$10^{11}$ M(n=1) AND $2.8\times$$10^{11}$ M(n=3.3) respectively. and the corresponding M/L are about 17 and 16 for both cases. (2) The optical image in the blue light, whose radius is 9.6 kpc, has 8$\times$$10^{10}$ M and 1.4$\times$$10^{11}$ M. These give the value of M/L about 5 and 8 respectively. (3) The masses and M/L of the nuclear region within 1.2 kpc are 4.0$\times$$10^{9}$ M 4.7$\times$$10^9$ M and 3, 4 for both cases. Those of the disk from 1.2 kpc to 9.6 kpc are 7.6$\times$1$10^{10}$M, 1.4$\times$$10^{11}$M, and 5, 8. (4) The masses of the outer halo extended to few hundreds kiloparsecs are 2.3$\times$$10^{11}$ M and 1.4$\times$$10^{11}$M. The corresponding M/L are about 62 and 37.

• Korea-Australia Rheology Journal
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• v.20 no.4
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• pp.253-260
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• 2008

A method based on transient shear flow dynamics of red cell aggregates was developed to investigate reversible re-aggregation processes with decreasing shear flow. In the microchannel-flow aggregometry, the aggregated red blood cells that are subjected to continuously decreasing shear stress in microchannel flow were measured with the use of a laser-scattering technique. Both the laser-backscattered intensity and pressure were simultaneously measured with respect to time, resulting in shear stress ranging from $0{\sim}35\;Pa$ for a time period of less than 30 seconds. The time dependent recording of the backscattered light intensity (syllectogram) yielded an upward convex curve with a peak point, which reflected the transition threshold of aggregation in the RBC suspensions. Critical-time and critical-shear stress corresponding to the peak point were examined by varying the initial pressure-differential and the micro channel depth, and these results showed good potential for being used as new aggregation indices. In the present study, these newly proposed indices were also validated by differentiating the effect of fibrinogen on RBC aggregation and then these indices were compared to the conventional indices that were measured by a rotational aggregometer.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2001.11a
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• pp.19-26
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• 2001

The wear characteristic of Zircaloy-4 tube, which is used for a cladding of light water reactor fuel rod, is investigated experimentally. The experiment is conducted with contacting the crossed tube specimens in air as well as in water at room temperature with various combination of contact normal force and sliding distance of reciprocating motion. The contour and the volume of each wear are examined to study the effect of contact condition and environment on wear. As a result, it is found that the wear volume in the water environment is larger than that in the air for all the contact (i.e., force and sliding distance) conditions. However, the wear depth is greater in air than in water if the contact normal force and the sliding distance are larger. These are explained by the ease of detachment of wear particles from the contact surface. On the other hand, workrate model is applied with the contact shear force range measured by our wear tester. Investigated is the correlation between the workrate and the wear volume increase rate of the present experiment. The parabolic curve is found to fit well for the present wear data.

• Proceedings of the KIEE Conference
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• 1999.07e
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• pp.2233-2235
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• 1999

The ac plasma display panel(PDP) is a flat light-emitting gas discharge device. Discharge gases directly take effects to the discharge phenomena of ac PDP. Therefore it is necessary to understand the characteristics of the discharge gases. In this paper, we have studied the effects of discharge gases by voltage transfer curves which show the discharge characteristics of ac PDP and the change of the effective wall capacitance during a discharge which depends on lateral spreading of charge distribution and the strength of discharge. As gas pressure increases, memory margins increases. and the firing voltage of a mixed gas is lower than that of a single gas such as He gas. The minimum sustain voltage and the maximum sustain voltage or firing voltage increases with decrease in the frequency. The effective wall capacitance increases as the discharge strength that is, the gap voltage between discharge electrodes increases.

• Corrosion Science and Technology
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• v.7 no.5
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• pp.243-251
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• 2008

Magnesium alloys become popular research topic in last decade due to its light weight and relatively high strength-to-weight ratio in the energy aspiration age. Almost all structure materials are supposed to suspend stress. Magnesium is quite sensitive to corrosive environment, and also sensitive to environmental assisted cracking. However, so far we have the limited knowledge about the environmental sensitive cracking of magnesium alloys. The corrosion fatigue (CF) test was conducted. Many factors' effects, like grain size, texture, heat treatment, loading frequency, stress ratio, strain rate, chemical composition of environment, pH value, relative humidity were investigated. The results showed that all these factors had obvious influence on the crack initiation and propagation. Especially the dependence of CF life on pH value and frequency is quite different to the other traditional structural metallic materials. In order to interpret the results, the electrochemistry tests by polarization dynamic curve and electrochemical impedance spectroscopy were conducted with and without stress. The corrosion of magnesium alloys was also studied by in-situ observation in environmental scanning electron microscopy (ESEM). The corrosion rate changed with the wetting time during the initial corrosion process. The pre-charging of hydrogen caused crack initiated at $\beta$ phase, and with the increase of wetting time the crack propagated, implying that hydrogen produced by corrosion reaction participated in the process.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.13 no.1
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• pp.92-100
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• 2017

Due to the presence of ferrite phase in the finished welds, austenitic stainless steel welds (ASSWs) are considered susceptible to the thermal aging embrittlement during long-term service in light water reactor environment. In this study, the thermal aging embrittlement of typical ASSWs, E308 and ER316L welds, were evaluated after the long-term exposure up to 20,000 h at $400^{\circ}C$, which is considered as an accelerated thermal aging condition. After thermal aging, the decrease of tensile ductility and fracture toughness was observed. The microstructure observation with high resolution transmission electron microscopy revealed that spinodal decomposition in ferrite phase of both E308 and ER316L welds would be the main cause of the degradation of mechanical properties. Also, it was shown that the difference of thermal ageing embrittlement between ER316L and E308 welds was significant, such that the reduction of fracture resistance for ER316L weld was much larger than that of E308 weld.

• Journal of Biomedical Engineering Research
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• v.18 no.4
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• pp.499-505
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• 1997

A non-invasive technique to measure absorption and scattering coefficients was investigated The reflected backscattered light from the surface of phantom and biological tissue was obtained by using a time-correlated single photon counting system in pico-second time domain. The absorption and scattering coefficients were acquired by the time of peak and asymptotic behavior of the time-resolved reflectance curve and agreed well the ones that is obtained with deconvolution method It was found that the approximation method was good for biological medium to calculate optical properties due to its convenience and accuracy.

• Bulletin of the Korean Chemical Society
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• v.24 no.1
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• pp.70-74
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• 2003

The heterogeneous bioluminescence immunoassay for digoxin was developed using photoprotein, native aequorin as a label and the site-directed immobilization technique based on avidin/biotin interaction. Aequorin is a bioluminescence protein, originally isolated from the jellyfish Aequoria Victoria and an attractive label in analytical applications because of sensitive detection due to virtually no background bioluminescent signal. Digoxin is a cardioactive drug, and its therapeutic level in serum is at low concentration with very narrow therapeutic index. The aequorin-digoxigenin conjugates were synthesized by the N-hydroxysuccinimide ester method and characterized in terms of bioluminescent residual activity. The resulting dose-response curve shows that the detection limit is $1.0\;{\times}\;10^{-10}\;M$ and a dynamic range is three orders of magnitude, which was obtained by $1.0\;{times}\;10^{-10}\;M$ conjugate and 0.9 μg/mL anti-digoxin antibody. Three structurally similar molecules to digoxin were examined for their cross-reactivity. None of these three compounds showed any crossreactivity with digoxin antibody employed in this study. Standard amounts of digoxin corresponding to the therapeutic range were spiked into the each serum solution. Study of the serum matrix effect indicated that correlation coefficient shows good agreement between luminescence light intensity between in buffer and in serum.

• The Bulletin of The Korean Astronomical Society
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• v.38 no.1
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• pp.29.2-29.2
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• 2013

The presence of dark energy, suggested from Type Ia supernovae (SNe) cosmology, is the most pronounced astronomical discovery made during the past decade. The basic assumption of this discovery is that the look-back time evolution of SNe luminosity would be negligible after light-curve correction. Several recent works, however, show that there are some differences in Hubble residual among host galaxies having different morphology and mass, indicating that SNe luminosity might be affected by population age. In order to investigate this more directly, we are continuing the YONSEI (YOnsei Nearby Supernovae Evolution Investigation) project, where we are obtaining low-resolution spectra of some 60 nearby early-type host galaxies. The early-type galaxies are preferred because the mean population ages and metallicities can be estimated from the absorption lines, and they are less affected by dust extinction. In this talk, we will report our progress in determining the ages and metallicities of host galaxies to investigate their correlation with the Hubble residual.