• Korean Journal of Materials Research
• /
• v.4 no.6
• /
• pp.681-686
• /
• 1994

Microwave Detector Using $YBa_{2}Cu_{3}O_{7-x}$, Grain Boundary Junction $YBa_{2}Cu_{3}O_{7-x}$ superconductor thin films were deposited on $LaAIO_{3}$ (100) single crystal substrates using a metal organic chemical vapor deposition (MOCVD) method. These films showed the critical temperature of about 9OK and critical current density of over $10^5/A \textrm{cm}^2$at 77K. These films showed granular structure with 0.5~1.5$\mu \textrm{m}$ grains. Bridge-type junctions, 6$\mu \textrm{m}$ in width and 6pm in length, were fabricated using the photolithography and the Ar ion milling techniques. Current-voltage (I-V) characteristics of these junctions with the microwave irradiation at 77K were studied. The critical current densities decreased as the irradiated microwave power increased. When microwaves were irradiated on the bridge at 77K. the I-V charateristics showed constant voltage stcp(Shapiro steps) at $\Delta$=nho/2e.

• Clean Technology
• /
• v.26 no.1
• /
• pp.7-12
• /
• 2020

Ti-SBA-15 catalysts doped with lanthanide ions (Ln/Ti-SBA-15) were successfully synthesized using conventional hydrothermal method. In addition, they were characterized by XRD, FT-IR, DRS, BET, and PL. The activity of these materials on the photocatalytic decomposition of methylene blue under ultraviolet light irradiation was also examined. Ti-SBA-15 catalysts doped with various lanthanide ions maintained their mesoporous structure. The pore size and pore volume of Ln/Ti-SBA-15 materials decreased but their surface area increased upon the doping of lanthanide ion. Ln/Ti-SBA-15 materials exhibited the type IV nitrogen isotherm with desorption hysteresis loop type H2, which was characteristic of mesoporous materials. The size of hysteresis increased in the doping of lanthanide ions on Ti-SBA-15 material. There was no absorption in the visible region (> 400 nm) regardless of the doping of lanthanide ions to TiO₂ particles, while the broad bands at 220 nm appeared at the Ln/Ti-SBA-15 samples, indicating the framework incorporation of titanium into SBA-15. 1 mol% Pr/ Ti-SBA-15 catalysts showed the highest photocatalytic activity on the decomposition of methylene blue but the Ti-SBA-15 catalysts doped with Eu, Er, and Nd ions showed lower activity compared to pure Ti-SBA-15 catalyst. The PL peaks appeared at about 410 nm at all catalysts while the excitonic PL signal was proportional to the photocatalytic activity for the decomposition of methylene blue.

• Korean journal of communication and information
• /
• v.27
• /
• pp.283-316
• /
• 2004

This study examines different news frames of local newspapers reporting the controversial 'Nu[lear Waste Site' issues which deeply split regions showing their intention to bid for the state affair. Three local papers were analyzed for this study, "Gwang-Ju-Il-bo" "Mae-il-sin-mun" and "Jun-buk-il-bo." Overall, the three local papers displayed widely divergent main news frames on the same issue. Firstly, "Gwang-Ju-Il-bo", and "Mae-il-sln-mun" showed the strong tendency of using 'counter frame' while "Jun-buk-il-bo" exhibited 'loral development frame'. Secondly, "Gwang-Ju-Il-bo", and "Mae-il-sin-mun" were frequently headlined 'Nuclear Waste Site', while "Jun-buk-il-bo" carried headlines 'Radioactive Waste Management Facility' overwhelmingly more often than the other two papers, indicating that headline key words are closely associated with the configuration of news frames. Thirdly, the main news frames remained consistent for "Gwang-Ju-Il-bo", and "Mae-il-sin-mun" even after the government's report about the possible connection of 'ion-beam irradiation-accelator' and 'Nuclear Waste Site.' On the other hand, "Jun-buk-il-bo" was significantly less headlined 'Nuclear Waste Site' while significantly more headlined "Radioactice Waste Management Facility." "Jun-Buk-il-bo" which is in stark contrast to the other two papers changed in its tone by increasing the 'local development frame' with decrease in the 'counter frame.' The "Jun-buk-il-bo"'s more frequent use of 'Radioactive Waste Management Facility' as a headline than "Nuclear Waste Management Equipment" is seen as its attempt to minimize negative image of Nuclear Waste and to promote favorable public opinion by highlighting aspects of economic benefits and the local development the construction would brind about. The major findings of this study further support the claim that media overage ends up a reality. The fact that Buan in Jun-buk Province made a successful bid for the construction is not a coincidence.

• Progress in Medical Physics
• /
• v.29 no.2
• /
• pp.59-65
• /
• 2018

This paper describes the clinical use of the dose verification of multileaf collimator (MLC)-based CyberKnife plans by combining the Octavius 1000SRS detector and water-equivalent RW3 slab phantom. The slab phantom consists of 14 plates, each with a thickness of 10 mm. One plate was modified to support tracking by inserting 14 custom-made fiducials on surface holes positioned at the outer region of $10{\times}10cm^2$. The fiducial-inserted plate was placed on the 1000SRS detector and three plates were additionally stacked up to build the reference depth. Below the detector, 10 plates were placed to avoid longer delivery times caused by proximity detection program alerts. The cross-calibration factor prior to phantom delivery was obtained by performing with 200 monitor units (MU) on the field size of $95{\times}92.5mm^2$. After irradiation, the measured dose distribution of the coronal plane was compared with the dose distribution calculated by the MultiPlan treatment planning system. The results were assessed by comparing the absolute dose at the center point of 1000SRS and the 3-D Gamma (${\gamma}$) index using 220 patient-specific quality assurance (QA). The discrepancy between measured and calculated doses at the center point of 1000SRS detector ranged from -3.9% to 8.2%. In the dosimetric comparison using 3-D ${\gamma}$-function (3%/3 mm criteria), the mean passing rates with ${\gamma}$-parameter ${\leq}1$ were $97.4%{\pm}2.4%$. The combination of the 1000SRS detector and RW3 slab phantom can be utilized for dosimetry validation of patient-specific QA in the CyberKnife MLC system, which made it possible to measure absolute dose distributions regardless of tracking mode.

• KSBB Journal
• /
• v.23 no.1
• /
• pp.70-76
• /
• 2008

Surface of hydrophobic media was modified to become hydrophilic by ion beam irradiation. Fixed bed biofilm reactors packed with or without surface modification were used to remove organics, nitrogen, and phosphorus from sewage. This system composed of anoxic/oxic cycles to increase the nutrient removal. A cylindrical polyethylene was used as a packing media in this study. With 12 hours of hydraulic retention time (HRT), the reactors with and without surface modification showed 95% and 92% $COD_{cr}$ removal, respectively. Both reactors showed over 95% $COD_{cr}$ removals for a longer HRT of 16 hours. Nitrogen removal ranged 54.8% to 70.2% for the surface modified system and 57.5% to 76.5% for the non-modified system under same condition. Finally, phosphorus removal ranged 59.4% to 69.8% for the surface modified system and 51.3% to 63.4% for the non-modified system under same condition. From this study organics and phosphorus were better removed in using surface modified media and vice versa for nitrogen removal.

• Polymer(Korea)
• /
• v.36 no.4
• /
• pp.525-530
• /
• 2012

In this study, silane-crosslinked organic/inorganic composite membranes were prepared by simultaneous irradiation grafting of binary monomer mixtures (styrene and 3-(trimethoxysilyl)propyl methacrylate (TMSPM)) with various compositions onto a poly(ethylene-alt-tetraethylene) (ETFE) film and followed by sol-gel processing and sulfonation to provide a silane-crosslinked structure and a proton conducting ability, respectively. The Fourier transform infrared spectroscopy (FTIR) and thermo gravimetric analysis (TGA) were utilized to confirm the crosslinking of ETFE-g-PS/PTMSPM films. The prepared membranes with similar ion exchange capacity but a different TMSPM content were selected and their membrane properties were compared. The ETFE-g-PSSA/PTMSPM membranes were characterized by water uptake, dimensional stability, and proton conductivity after sulfonation. The membrane electrode assemblies (MEA) of the prepared membranes were fabricated and their single cell performances were measured.

• Korean Journal of Food Science and Technology
• /
• v.31 no.6
• /
• pp.1495-1502
• /
• 1999

Gamma-irradiated beef and chicken at the dose levels of 0.5 to 10 kGy were subjected to the detection of radiation-induced 2-alkylcyclobutanones whether irradiated or not. Radiation-induced 2-alkylcyclobutanones were extracted from beef and chicken fats, separated by florisil column chromatography and identified with GC/MS method by selected ion monitoring(SIM). When beef and chicken were irradiated, 2-dodecylcyclobutanone, 2-tetradecylcyclobutanone and 2-(5'-tetradecenyl)cyclobutanone were formed from palmitic, stearic and oleic acids. Concentrations of 2-alkylcyclobutanones were linearly increased with the dose levels of irradiation and depended upon the composition of fatty acids in beef and chicken. Radiation-induced 2-alkylcyclobutanones in irradiated beef and chicken were remarkably detected at 1 kGy and over, while these compounds were not detected in non-irradiated samples. The concentrations of radiationinduced 2-alkylcyclobutanones were relatively constant during 6 months.

• KSBB Journal
• /
• v.25 no.5
• /
• pp.429-436
• /
• 2010

Keratinase is widely used in certain industrial applications. The present study sought to improve the culture conditions of Bacillus subtilis SMMJ-2 to facilitate mass production of keratinase. Strain SMMJ-2 was irradiated by ultraviolet light and the resulting isolates were tested for keratinase activity. Isolates displaying elevated keratinase activity were selected and used to determine the optimum temperature (24, 30, 37, 45, $55^{\circ}C$) for bacterial keratinase production during a 4 day incubation period. The highest enzyme activity (55 units/mL/min), from a Bacillus subtilis SMMJ-2 mutant (mutant No. 2) was demonstrated following incubation at $30^{\circ}C$. The effects of carbon and nitrogen sources on keratinase production were confirmed by measuring the enzyme activity from the culture broth of the mutant strain cultured in various media containing different carbon source and nitrogen sources during a 4 day period. The optimal medium composition for producing keratinase consisted of 1% glucose, 0.7% $K_2HPO_4$, 0.2% $K_2HPO_4$, and 1.2% soybean meal. Optimal initial pH and temperature for producing keratinase were 7.0 and $30^{\circ}C$, respectively. Keratinases produced by B. subtilis SMMJ-2 and the mutant No. 2 were purified from the culture broth which used soybean meal as a nitrogen source. Membrane ultrafiltration, DEAE-sephacel ion exchange and Sephadex G-100 gel chromatography were used to purify the enzymes. The purified keratinases from both B. subtilis SMMJ-2 and the mutant No. 2 showed single bands and their molecular weights were estimated as 28 kDa and 42 kDa, respectively on SDS-polyacrylamide gel electrophoresis.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.19 no.1
• /
• pp.64-78
• /
• 2011

Surface of hydrophobic polyethylene membrane was modified to become hydrophilic by ion beam irradiation. Submerged membrane filtration reactors contained pristine membrane or surface-modified membrane and the influent to reactors was pickled radish wastewater. The objectives of this study was to investigate the variation of flux and pressure and the characteristics of pollutant removal such as organics, suspended solids and nutrients with time. The result of experiments using intermittent pristine membrane showed the occurrence of severe fouling by increasing permeate pressure rapidly in case of pickled radish wastewater but in synthetic wastewater, this phenomenon was not occurred. In experiments of variation flux after chemical cleaning and water cleaning in pristine membrane, chemical cleaning must be necessary for renewals of pollutant membrane. Performance of intermittent operation is higher than that of continuous operation. Reaching fouling time in the case of surface-modified membrane is 6 times as long as pristine membrane. According this reason, replacement expense of surface-modified membrane could be 1/6 of that of pristine membrane. Effluent from this process was relatively good water quality and performance in the removal efficiency of SS, nitrogen and phosphorus was particularly higher.

• Progress in Medical Physics
• /
• v.32 no.4
• /
• pp.99-106
• /
• 2021

Purpose: In this study, we aimed to manufacture a patient-specific gel phantom combining three-dimensional (3D) printing and polymer gel and evaluate the radiation dose and dose profile using gel dosimetry. Methods: The patient-specific head phantom was manufactured based on the patient's computed tomography (CT) scan data to create an anatomically replicated phantom; this was then produced using a ColorJet 3D printer. A 3D polymer gel dosimeter called RTgel-100 is contained inside the 3D printing head phantom, and irradiation was performed using a 6 MV LINAC (Varian Clinac) X-ray beam, a linear accelerator for treatment. The irradiated phantom was scanned using magnetic resonance imaging (Siemens) with a magnetic field of 3 Tesla (3T) of the Korea Institute of Nuclear Medicine, and then compared the irradiated head phantom with the dose calculated by the patient's treatment planning system (TPS). Results: The comparison between the Hounsfield unit (HU) values of the CT image of the patient and those of the phantom revealed that they were almost similar. The electron density value of the patient's bone and brain was 996±167 HU and 58±15 HU, respectively, and that of the head phantom bone and brain material was 986±25 HU and 45±17 HU, respectively. The comparison of the data of TPS and 3D gel revealed that the difference in gamma index was 2%/2 mm and the passing rate was within 95%. Conclusions: 3D printing allows us to manufacture variable density phantoms for patient-specific dosimetric quality assurance (DQA), develop a customized body phantom of the patient in the future, and perform a patient-specific dosimetry with film, ion chamber, gel, and so on.