• Bulletin of the Korean Chemical Society
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• v.11 no.2
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• pp.118-123
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• 1990

X-ray photoelectron spectra have been obtained and comparisons have been made for 1-2-3 and 2-1-1 phases of YBaCuO compounds. The photoelectron binding energies of all the constituent elements are consistently larger for the 2-1-1 phase than for the 1-2-3 phase. The peak intensities reflect different stoichiometries of the two phases. For the superconducting 1-2-3 phase, its degradation in air and interaction with water and carbon dioxide were examined by taking core level spectra of all the elements. It appears that yttrium is the most affected by exposure to air, since it undergoes a rapid change to carbonate when water and subsequently carbon dioxide are introduced.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.2
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• pp.203-209
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• 2013

Digital Radiography (DR) has improved a quality of resolution based on a wide dynamic range, high detective quantum efficiency (DQE), and modulation transfer function (MTF), compared with film/screen(F/s). Unlike expectation that a low level of radiation can be used in examination, high level of signal to noise ratio(SNR) due to over-exposure caused increase of exposed dose to patients. Also, the auto exposure control (AEC) using Kilovolage(kVp) in F/S can cause over-exposure. Hence, in this study, we proposed a proper method for using DR, in which effect of tubing Kilovolage on device's image, DR MTF measurement with changes of tubing current (mA), and the quantitative evaluation of skull phantom captured images' PSNR were evaluated. Changes of contrast with tubing Kilovolage can be improved by retouching, and MTF changes according to tubing current(1.41~1.39 lp/mm in 50% area, and 3.19~2.8 lp/mm in 10% area) does not influence on resolution of image. As a result, high tubing Kilovoltage, and tubing current will be suitable to use of DR.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.63.2-63.2
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• 2015

Controlling and sensing spin states of magnetic molecules such as metallo-porphyrins at the single molecule level is essential for spintronic molecular device applications. Axial coordinations of diatomic molecules to metallo-porphyrins also play key roles in dynamic processes of biological functions such as blood pressure control and immune response. However, probing such reactions at the single molecule level to understand their physical mechanisms has been rarely performed. Here we present on our single molecule association and dissociation experiments between diatomic and metallo-porphyrin molecules on Au(111) describing its adsorption structures, spin states, and dissociation mechanisms. We observed bright ring shapes in NO adsorbed metallo-porphyrin compelxes and explained them by considering tilted binding and precession motion of NO. Before NO exposure, Co-porphryin showed a clear zero-bias peak in scanning tunneling spectroscopy, a signature of Kondo effect in STS, whereas after NO exposures it formed a molecular complex, NO-Co-porphyrin, that did not show any zero-bias feature implying that the Kondo effect was switched off by binding of NO. Under tunneling junctions of scanning tunneling microscope, both positive and negative energy pulses. From the observed power law relations between dissociation rate and tunneling current, we argue that the dissociations were inelastically induced with molecular orbital resonances. Our study shows that single molecule association and dissociation can be used to probe spin states and reaction mechanisms in a variety of axial coordination between small molecules and metallo-porphyrins.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.32 no.4
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• pp.402-413
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• 2022

Objectives: In this study, the scale of exceeding the extreme heat exposure standard at the construction site was estimated using the nationally approved statistical data and wet bulb globe temperature modeling method. By comparing and analyzing the modeling results with the existing work environment monitoring results, the risk of heat exposure at outdoor construction sites was considered. Methods: Using the coordinates of second level administrative districts and meteorological observatories as the key, the automated synoptic observing system data and building permit data for 2021 were matched. The wet-bulb temperature was obtained using Stull's formula, and the globe temperature was obtained using the Tg_KMA2006 model. WBGT was calculated using these. Excess rates were obtained compared to exposure limits for heavy work-continuous work and moderate work-25% rest. It was compared with the results of the work environment monitoring in 2020. Results: As a result, 1,827,536 cases were estimated for 11,052 workplaces in one year. This is much higher than the 5,116 cases of 3818 workplaces of the existing work environment monitoring results. It is confirmed that the exposure limit was exceeded in 10.6~24.0% of the entire period and 70.2~84.1% of the peak period of the heat wave. It is very high compared to 0.9% of the existing work environment monitoring result. Conclusions: It is necessary to improve the system of monitoring and statistics related to extreme heat. Additional considerations are needed regarding WBGT estimation methods, meteorological data, and evaluation time. Various follow-up risk assessment studies for other industries and time series need to be continued.

• Journal of radiological science and technology
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• v.44 no.4
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• pp.327-333
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• 2021

Magnetic resonance imaging(MRI) uses strong magnetic field to image the cross-section of human body and has excellent image quality with no risk of radiation exposure. Because of above-mentioned advantages, MRI has been widely used in clinical fields. However, the noise generated in MRI degrades the quality of medical images and has a negative effect on quick and accurate diagnosis. In particular, examining a object with a detailed structure such as brain, image quality degradation becomes a problem for diagnosis. Therefore, in this study, we acquired T2 weighted 3D data of multiple sclerosis disease using BrainWeb simulation program, and used quantitative evaluation factors to find appropriate slice thickness among 1, 3, 5, and 7 mm. Coefficient of variation and contrast to noise ratio were calculated to evaluate the noise level, and root mean square error and peak signal to noise ratio were used to evaluate the similarity with the reference image. As a result, the noise level decreased as the slice thickness increased, while the similarity decreased after 5 mm. In conclusion, as the slice thickness increases, the noise is reduced and the image quality is improved. However, since the edge signal is lost due to overlapped signal, it is considered that selecting appropriate slice thickness is necessary.

• Journal of fish pathology
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• v.23 no.1
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• pp.9-16
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• 2010

We determined the effects of temperature shifts on the kinetics of the numbers of antibody-secreting cell (ASC) in the olive flounder Paralichthys olivaceus immunised with formalin-killed Edwardsiella tarda. When fish that were acclimated to $22^{\circ}C$ and immunised at that temperature were transferred to a lower temperature ($12^{\circ}C$) at a various times (immediately, 1, 2 or 4 weeks) after immunisation, both further differentiation of B cells and secretion of antibody from the ASC developed at $22^{\circ}C$ were suppressed at $12^{\circ}C$. However, in the converse experiment ($12^{\circ}C$ to $22^{\circ}C$), the magnitude of the humoral immune response was recovered independent of the time of the transfer after immunisation at low temperature, even though the peak levels of each transferred group did not reach the level found in $22^{\circ}C$ control group. The results were confirmed by counting the number of specific antibody secreting cells (SASC) in the spleen. This study provides the evidences of the immune reaction that the potential for antibody production in B cells of flounder, the most important species in aquatic industry of Korea, immunized at high temperature is suppressed by subsequent exposure to low temperature and that low temperature-induced humoral immuno suppression can be reversed by exposure to a higher temperature.

• Journal of the Korean Society of Radiology
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• v.7 no.6
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• pp.415-418
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• 2013

Thermoluminescent dosimeter utilizes the fact that when irradiated specimen is heated up, some part of the absorbed energy is emitted from the specimen as light with longer wavelength. This research aims at analyzing the glow curves of four TLD-100 exposed to a magnetic field and those of other four TLD-100 not exposed to one by treating them with heat and irradiating them, which are commonly used as thermoluminescent dosimeter, in the same condition. As the result of the experiment, regarding the electrons captured by irradiation, some of the electrons of lower traps were combined with positive holes of valence band through the exposure to a magnetic field, and the peak size decreased by 48%. The reduction in the size of the lower traps caused the TLD-100 exposed to a magnetic field to display a low level of dose. In addition, low traps estimated activation energies are 1.6 eV and 1.5 eV.

• Journal of the Korean Society of Radiology
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• v.8 no.4
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• pp.181-187
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• 2014

The purpose of this study were to analyze the characteristic of the glow curves in order to the glow temperature of the thermoluminescent dosimeters (TLDs) for the absorbed dose measurement of the radiation therapy. In this study, we was used the TLDs of the LiF:Mg${\cdot}$Ti, LiF:Mg${\cdot}$Cu${\cdot}$P, $CaF_2$:Dy, $CaF_2$:Mn (Thermo Fisher Scientific Inc., USA). The source-to-solid dry phantom (RW3 slab, IBA Dosmetry, Germany) surface distance was set at 100 cm, and the exposure dose of 100 MU (monitor unit) was used 6- and 15-MV X-rays, and 6- and 12-MeV electron beams in the reference depth, respectively. After the radiations exposure, we were to analyze the glow curves by using the TL reader (Hashaw 3500, Thermo Fisher Scientific Inc., USA) at the fixed heating rate of $15^{\circ}C/sec$ from $50^{\circ}C$ to $260^{\circ}C$. The glow peaks, the trapping level in the captured electrons and holes combined with the emitted light, were discovered the two or three peak. When the definite increasing the temperature of the TLDs, the maximum glow peak representing the glow temperature was follow as; $LiF:Mg{\cdot}Ti$: $185.5{\pm}1.3^{\circ}C$, $LiF:Mg{\cdot}Ti$: $135.0{\pm}5.1^{\circ}C$, $CaF_2$:Dy: $144.0{\pm}1.6^{\circ}C$, $CaF_2$:Mn: $294.3{\pm}3.8^{\circ}C$, respectively. Because the glow emission probability of the captured electrons depend on the heating temperature after the exposure radiation, TLDs by applying the fixed heating rate, the accuracy of measurement will be able to improve within the absorbed dose measurement of the radiation therapy.

• Journal of fish pathology
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• v.14 no.2
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• pp.97-102
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• 2001

Olive flounder, Paralichthys olivaceus known as an one of the major aquacultured species in Korea were exposed to cadmium(Cd) with different protocols and analyzed the effects of exposure on the immune response. Antibody levels in sera of the group exposed to Cd(20ppb) by immersion method from 2 weeks before immuniztion with formalinised Edwardsiella tarda(E. tarda) KFE entigen to the end of experiment reached to peak level faster than that of the non-exposed group. After this peaking time the levels decreased much at a faster rate compared to the non-exposed group. This tendency was also appeared in the numbers of specific antibody secreting cells(SASC) analyzed with the enzyme-linked immunospot (ELISPOT)-assay technique in the splenocytes of the experimental groups exposed to Cd with different ways. Interestingly, the group exposed to Cd for 2 weeks before immunization also showed increased numbers of SASC unlikely the antibody production and suggested a more critical influence of cadmium exposure in early stage of immune reaction. Artificial infection with live E. tarda KFE induces 100% mortality in the flounder exposed to cadmium throughout the experimental period from two weeks before the immunization. It may imply that some other factors related to specific immunity are involving in the defence system of flounder exposed to Cd. Taked together. Cd exposure may induce temporaily stimulatory or indhibitory effects on the immune reaction, but suppress the physiological systems for the resistant against the infective agents with other toxic effects.

• Journal of Photoscience
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• v.9 no.2
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• pp.249-251
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• 2002

The avian pineal as well as the retina has been known to contain several types of photoreceptors with different visual pigments such as rhodopsin, iodopsin and the pineal specific opsin, pinopsin. These organs are also known to have circadian clock to regulate melatonin production. Exposure of animals to light causes a decline of the melatonin level and the phase shifts of melatonin rhythms in the pineal and retina. Therefore, the circadian clock system of these organs seem to consist of three elements, i.e., light input, oscillator and melatonin output systems. In birds, it was suggested that rhodopsin might be involved in the entrainment of pineal melatonin rhythms from the action spectrum experiment for controlling NAT activity rhythms. However, there are much more pinopsin-immunoreactive (Pino-IR) cells than rhodopsin (Rho-IR) and iodopsin (Iodo-IR) cells in the avian pineal. We found that Pino-IR cells appeared earlier embryonic stages than Rho-IR and Iodo-IR cells. So, we tried to identify the visual pigments involved in the circadian melatonin rhythms in the pineal and retina. Organ cultured pineals were exposed to monochromatic light to find out which opsin participates in regulation of melatonin rhythms. The action spectra showed a peak at 475nm, suggesting that pinopsin is the major photopigment to regulate melatonin production in birds.