• Journal of the Korean GEO-environmental Society
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• v.24 no.3
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• pp.23-27
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• 2023

Graphitic carbon nitride (g-C₃N₄) has been used as effective photocatalyst for degradation of antibiotics under visible light irradiation. However, the fast recombination of hole-electron pair may limit their photocatalytic efficiency. In our study, Ag was grafted on g-C₃N₄/g-C₃N₄ isotype heterojunction by a microwave-assisted decomposition method. The structure and physical properties of heterojunction photocatalyst were characterized through X-ray diffraction, UV-DRS, FT-IR, and Photoluminescence analyses. Ag decorated g-C₃N₄/g-C₃N₄ isotype heterojunction exhibited excellent photocatalytic activity for degradation of sulfamethoxazole under irradiation under visible light irradiation within 210 min, which is higher than g-C₃N₄/g-C₃N₄ isotype heterojunction and bulk g-C₃N₄. The addition of Ag may broaden the visible light absorption and restrict the recombination of hole-electron pair because of the surface plasmons resonance, resulting in the improving the photocatalytic activity.

• Journal of Korean Neurosurgical Society
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• v.42 no.3
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• pp.200-204
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• 2007

Objective : Radiation therapy is an important treatment for brain tumor. However, serious complications such as radiation necrosis can occur and it may be secondary to the expression of acute phase genes, like cytokines. In particular, inflammatory cytokines (IL-$1{\beta}$, TNF-${\alpha}$) and other immunomodulatory cytokines (TNF-${\alpha}$, TGF-${\beta}1$) might be changed after irradiation (high single dose irradiation). Although it has been reported that IL-1 level is remarkably elevated within 8 week after the irradiation to the rat brain. the change of cytokines levels at acute phase (within 24 hours) has not been reported. In the present study, we examined TNF-${\alpha}$, TGF-${\beta}1$, and IL-$1{\beta}$ levels in acute phase to clarify the early effect of cytokines on the radiation-induced brain damage. Methods : Fifty Sprague-Dawley rats were used and these were divided into irradiation group and control group. After a burr-hole trephination on the right parietal area using a drill, a single 10Gy was irradiated at the trephined site. Their forebrains were extirpated at 30 min, 2 hr, 8 hr, 12 hr and 24 hr, respectively and examined for the expression of TNF-${\alpha}$, TGF-${\beta}1$, and IL-$1{\beta}$. Results : The expression of TNF-${\alpha}$ and TGF-${\beta}1$ were decreased until 12 hr after irradiation but elevated thereafter. The expression of IL-1 was peak at 8 hr and then decreased until 12 hr but elevated after this time window. The present study indicated that expression of cytokines (TNF-${\alpha}$, TGF-${\beta}1$ and IL-$1{\beta}$) were increased at 24 hr after the irradiation to the rat brain. IL-$1{\beta}$ level, on the other hand. reached peak at 8 hr after radiation injury. Conclusion : These findings indicate that IL-1, among various cytokines, may have a more important role in the inflammatory reaction by radiation injury at acute phase and provide some clues for better understanding of the pathogenesis of radiation injury.

• Applied Microscopy
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• v.37 no.2
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• pp.135-142
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• 2007

This research investigated morphological changes of ovarian follicle according to dose of irradiation when adult mice were exposed to X-rays from 6 MeV LINAC. At day 3 after irradiation of 200 cGy, 400 cGy and 600 cGy X-ray to the hole body of mice, the ovaries collected and stained with TUNEL. The normal follicles and atretic follicles were identified to apoptosis by the staining with TUNEL. In the atretic follicles of the normal ovary, the apoptotic bodies were well appeared and stained brown color. Almost of the follicles following irradiation are stained with TUNEL, but the sensitivity of reaction is weaker than that in irradiation of 400 cGy and 600 cGy X-ray. The granulosa cells of the radiated normal follicle by 400 cGV are shown brown color. In this stage, the nucleus of granulosa cells in the atrectic follicles are condensed and picknotic feature. The size of the radiated follicle by 600 cGy are decreased than the normal follicles. The atropic follicles are filled with apoptotic bodies which change of granulosa cells and theca cells by influence of X-ray. All of cell in the follicles are strongly positive stained with TUNEL by irradiation of 600 cGy.

• Journal of the Optical Society of Korea
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• v.14 no.4
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• pp.321-325
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• 2010

We analyze the current density - voltage (J - V) curve of a Cu(In,Ga)$Se_2$ (CIGS) thin-film solar cell measured at different irradiation power densities. For the solar-cell sample investigated in this study, the fill factor and power conversion efficiency decreased as the irradiation power density (IPD) increased in the range of 2 to 5 sun. Characteristic parameters of solar cell including the series resistance ($r_s$), the shunt resistance ($r_{sh}$), the photocurrent density ($J_L$), the saturation current density ($J_s$) of an ideal diode, and the coefficient ($C_s$) of the diode current due to electron-hole recombination via ionized traps at the p-n interface are determined from a theoretical fit to the experimental data of the J - V curve using a two-diode model. As IPD increased, both $r_s$ and $r_{sh}$ decreased, but $C_s$ increased.

• Clean Technology
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• v.11 no.3
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• pp.123-128
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• 2005

Among various metal oxides semiconductors, $TiO_2$ is the most studied semiconductor for environmental clean-up applications due to its unique ability in photocatalyzing various organic contaminants, its chemical inertness, and nontoxicity. $TiO_2$, however, has a few drawbacks to be solved such as reactivity mainly working under ultraviolet irradiation (${\lambda}$ < 387 nm) and electron - hole recombination on $TiO_2$. In this study, to extend the absorption range of $TiO_2$ into the visible range and enhance electron - hole separation, we synthesized platinum (Pt) deposited $C-TiO_2$. The presence of Pt as an electron sink has been known to snhance the separation of photogenerated electron-hole pairs and induce the thermal decomposition. The characterization of as-synthesized $Pt-C-TiO_2$ was performed by Transmission Electron Microscopic (TEM), the Brunuer-Emmett-Teller (BET) method, X-ray Diffractometer (XRD), UV-vis spectrometer (UV-DRS), and X-ray Photoelectron Spectroscopy (XPS). In order to estimate the photocatalytic activity of the synthesized materials, the photoelectron Spectroscopy (XPS). In order to estimate the photocatalytic activity of the synthesized materials, the photodegradation experiment of an azo dye (Acid Red 44; $C_{10}H_7N=NC_{10}H_3(SO_3Na)_2OH$)was carried out by using an Xe arc lamp (300 W, Oriel). A 420 nm cut-off filter was used for visible light irradiation. From the results, Pt-deposited $C-TiO_2$ showed a far superior phothdegradation activity to Degussa P25, the commercial product under the irradiation of visible light and enhanced photocatalytic activity of visible-working $C-TiO_2$. This is a useful result into the application for the purification system of dye wastewater using visible energy of sun light.

• Journal of radiological science and technology
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• v.33 no.3
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• pp.185-192
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• 2010

Platelets originating from Megakaryocyte are sensitive to radiation along with white blood cells, and thus these platelets are used as an index of radiation hazard as they decrease in advance. Thus, when there is a scarcity of platelets, dot hemorrhage occurs and it leads to decrease of blood corpuscle and a decline in immunity. In particular, when 4~6 Gy whole body irradiation is received, after three weeks, the platelets will decrease to the lowest level, which can be a cause of death by bleeding and anemia. Therefore, this study tried to identify the mechanism of platelet damage and protection effect. The protection substance used in the experiment is Alliin, which is a component of garlic, and it was observed by an Transmission Electron Microscope(TEM) after its injection to the rat's tail vein. In the study, it was found that the cell membrane was severely damaged in a 10-day progressed platelet organ after receiving 5 Gy irradiation. It billowed as balloon-like figure and the glycocalyx became hyperplasia. The minute organ was damaged to the point that it was beyond recognition in a 20-day progressed platelet organ after receiving irradiation, and the cytoplasmic contents were exposed to epilepsy parts and outrageously damaged. Furthermore, the form of granules could also not be observed. A hole was formed in the middle, and the damaged organ was found in a 30-day progressed platelet. However, the form of granules was consistently maintained in the experiment group injecting Alliin, as with the control group, and there was no damage to the cell membrane recognized. Thus, it was possible to verify the effectiveness of radiation protection of the platelet when Alliin was injected to the blood vessel.

• Bulletin of the Korean Chemical Society
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• v.31 no.7
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• pp.1941-1944
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• 2010

The heterojunction structures of BiOCl/$Bi_3O_4Cl$, exhibiting considerable visible-light photocatalytic efficiency, were prepared by a simple wet-chemical process at ambient condition. The prepared nanocomposites were characterized by XRD, TEM, and UV-visible diffuse reflectance spectra. Under visible light (${\lambda}\geq$420 nm) irradiation, BiOCl/$Bi_3O_4Cl$ exhibited an enhanced photocatalytic activity in decomposing 2-propanol (IP) in gas phase and salicylic acid (SA) in aqueous solution, whereas the bare BiOCl and $Bi_3O_4Cl$ showed negligible activities. It is deduced that the remarkable visible-light photocatalytic activity of the BiOCl/$Bi_3O_4Cl$ originates from the hole $(h^+)$ transfer between VB of the $Bi_3O_4Cl$ and BiOCl semiconductors.

• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.597-600
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• 1998

When a semiconductor(pMOSFET) sensor is exposed to ionizing radiation, electrons/holes are generated in its oxide layer. By the phenomenon of hole traps in oxide layer during their move, the characteristics of semiconductor is changed. This paper describes the output characteristic changes of two kind of pMOSFET(domestic, japan) after C0-60 ${\gamma}$-irradiation on them for their application as radiation accumulated dose monitoring sensors. We found the threshold voltage shifts (VT) of pMOSFETs in proportion to irradiated radiation dose and their linear properties. These results make us confirm that we will be able to develop good accumulated radiation dose monitoring sensors.

• Journal of KSNVE
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• v.10 no.2
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• pp.261-268
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• 2000

The instrumented capsule is subjected to flow-induced vibration(FIV) due to the flow of the primary coolant and then the structural integrity of the capsule during irradiation in the HANARO reactor is an issue of major concern. For this purpose the acceleration was measured by four accelerometers attached to the protection tube of the capsule mainbody and the displacement of test holes was calcultated using commercial finite element program ANSYS to evaluate the structural interference with the neighboring flow tubes under the reactor operating condition. The calculated displacements of test holes in the reactor in-core were found to be lower than the values of allowable design criteria.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.4
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• pp.53-60
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• 1998

The purpose of this paper is to meausre the electrophotographic characteristics of double-layered organic photoreceptor and to evaluate an application for the laser beam printer drum. The characte carrier generation layer(CGL) of double-layered photoreceptor was fabricated with .tau.-H$_{2}$Pc which has high photosensitivity in the near-infrareed region(thickness is about 0.3.mu.m), and Oxadiazole derivative was chosen as a charge carrier transport layer(CTL) because of its high hole mobility. To observe the electrophotographic characteristics of the photoreceptor, we measured the charge acceptance, dark-decay ratio, residual potential after light irradiation. From the result of this study, proper thickness of CTL was about 10.mu.m. Also it's realized that electrophotographic characteristics of the photoreceptor were depend on the thickness of the CTL and the initial surface potential.