• Journal of Radiation Protection and Research
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• v.41 no.1
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• pp.41-47
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• 2016

Background: For the accurate dose assessment in radiation therapy, energy spectrum of the photon beam generated from the linac head is essential. The aim of this study is to develop the technique to accurately unfolding the energy spectrum with the transmission analysis method. Materials and Methods: Clinical linear accelerator and Monet Carlo method was employed to evaluate the transmission signals according to the thickness of the observer material, and then the response function of the ion chamber response was determined with the mono energy beam. Finally the energy spectrum was unfolded with HEPROW program. Elekta Synergy Flatform and Geant4 tool kits was used in this study. Results and Discussion: In the comparison between calculated and measured transmission signals using aluminum alloy as an attenuator, root mean squared error was 0.43%. In the comparison between unfolded spectrum using HEPROW program and calculated spectrum using Geant4, the difference of peak and mean energy were 0.066 and 0.03 MeV, respectively. However, for the accurate prediction of the energy spectrum, additional experiment with various type of material and improvement of the unfolding program is required. Conclusion: In this research, it is demonstrated that unfolding spectra technique could be used in megavoltage photon beam with aluminum alloy and HEPROW program.

• Progress in Medical Physics
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• v.23 no.3
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• pp.154-161
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• 2012

Digital Radiography (DR) has rapidly developed in megavoltage X-ray imaging (MVI). Thus, a very simple and general quality assurance (QA) method is required. The purpose of this study was to evaluate the modulation transfer function (MTF), the noise power spectrum (NPS) and the detective quantum efficiency (DQE) for MVI using general QA method and computed radiography (CR) device. We used tungsten edge block with $19{\times}10{\times}1cm^3$ thickness and 6MV energy. For detector, CR-IP (image plate), CR-IP-lead, the CR-IP-back (lanex TM fast back screen), CR-IP-front (lanex TM fast front screen) were used and pre-sampling MTF was calculated. The MTF of CR-IP-front showed the highest value with 1.10 lp/mm although the CR-IP showed the only 0.70 lp/mm. The best NPS was observed in CR-IP front screen. According to the increase in spatial frequency, our results showed that DQE was approximately 1.0 cycles/mm. The present study demonstrates that the QA method with our home-made edge block can be used to evaluate MTF, NPS and DQE for MVI.

• Clean Technology
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• v.20 no.3
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• pp.306-313
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• 2014

Nanoporous $TiO_2$ films are commonly used as working electrodes in dye-sensitized solar cells (DSSCs). So far, there have been attempts to synthesize films with various $TiO_2$ nanostructures to increase the power-conversion efficiency. In this work, vertically aligned rutile $TiO_2$ nanorods were grown on fluorinated tin oxide (FTO) glass by hydrothermal synthesis, followed by deposition of an anatase $TiO_2$ film. This new method of anatase $TiO_2$ growth avoided the use of a seed layer that is usually required in hydrothermal synthesis of $TiO_2$ electrodes. The dense anatase $TiO_2$ layer was designed to behave as the electron-generating layer, while the less dense rutile nanorods acted as electron-transfer pathwaysto the FTO glass. In order to facilitate the electron transfer, the rutile phase nanorods were treated with a $TiCl_4$ solution so that the nanorods were coated with the anatase $TiO_2$ film after heat treatment. Compared to the electrode consisting of only rutile $TiO_2$, the power-conversion efficiency of the rutile-anatase hybrid $TiO_2$ electrode was found to be much higher. The total thickness of the rutile-anatase hybrid $TiO_2$ structures were around $4.5-5.0{\mu}m$, and the highest power efficiency of the cell assembled with the structured $TiO_2$ electrode was around 3.94%.

• Electrical & Electronic Materials
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• v.12 no.7
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• pp.7-11
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• 1999

Fully sealed field emission display in size of 4.5 inch has been fabricated using single-wall carbon nanotubes-organic vehicle com-posite. The fabricated display were fully scalable at low temperature below 415$^{\circ}C$ and CNTs were vertically aligned using paste squeeze and surface rubbing techniques. The turn-on fields of 1V/${\mu}{\textrm}{m}$ and field emis-sion current of 1.5mA at 3V/${\mu}{\textrm}{m}$ (J=90${\mu}{\textrm}{m}$/$\textrm{cm}^2$)were observed. Brightness of 1800cd/$m^2$ at 3.7V/${\mu}{\textrm}{m}$ was observed on the entire area of 4.5-inch panel from the green phosphor-ITO glass. The fluctuation of the current was found to be about 7% over a 4.5-inch cath-ode area. This reliable result enables us to produce large area full-color flat panel dis-play in the near future. Carbon nanotubes (CNTs) have attracted much attention because of their unique elec-trical properties and their potential applica-tions [1, 2]. Large aspect ratio of CNTs together with high chemical stability. ther-mal conductivity, and high mechanical strength are advantageous for applications to the field emitter [3]. Several results have been reported on the field emissions from multi-walled nanotubes (MWNTs) and single-walled nanotubes (SWNTs) grown from arc discharge [4, 5]. De Heer et al. have reported the field emission from nan-otubes aligned by the suspension-filtering method. This approach is too difficult to be fully adopted in integration process. Recently, there have been efforts to make applications to field emission devices using nanotubes. Saito et al. demonstrated a car-bon nanotube-based lamp, which was oper-ated at high voltage (10KV) [8]. Aproto-type diode structure was tested by the size of 100mm $\times$ 10mm in vacuum chamber [9]. the difficulties arise from the arrangement of vertically aligned nanotubes after the growth. Recently vertically aligned carbon nanotubes have been synthesized using plasma-enhanced chemical vapor deposition(CVD) [6, 7]. Yet, control of a large area synthesis is still not easily accessible with such approaches. Here we report integra-tion processes of fully sealed 4.5-inch CNT-field emission displays (FEDs). Low turn-on voltage with high brightness, and stabili-ty clearly demonstrate the potential applica-bility of carbon nanotubes to full color dis-plays in near future. For flat panel display in a large area, car-bon nanotubes-based field emitters were fabricated by using nanotubes-organic vehi-cles. The purified SWNTs, which were syn-thesized by dc arc discharge, were dispersed in iso propyl alcohol, and then mixed with on organic binder. The paste of well-dis-persed carbon nanotubes was squeezed onto the metal-patterned sodalime glass throuhg the metal mesh of 20${\mu}{\textrm}{m}$ in size and subse-quently heat-treated in order to remove the organic binder. The insulating spacers in thickness of 200${\mu}{\textrm}{m}$ are inserted between the lower and upper glasses. The Y\ulcornerO\ulcornerS:Eu, ZnS:Cu, Al, and ZnS:Ag, Cl, phosphors are electrically deposited on the upper glass for red, green, and blue colors, respectively. The typical sizes of each phosphor are 2~3 micron. The assembled structure was sealed in an atmosphere of highly purified Ar gas by means of a glass frit. The display plate was evacuated down to the pressure level of 1$\times$10\ulcorner Torr. Three non-evaporable getters of Ti-Zr-V-Fe were activated during the final heat-exhausting procedure. Finally, the active area of 4.5-inch panel with fully sealed carbon nanotubes was pro-duced. Emission currents were character-ized by the DC-mode and pulse-modulating mode at the voltage up to 800 volts. The brightness of field emission was measured by the Luminance calorimeter (BM-7, Topcon).

• Journal of Korean Ophthalmic Optics Society
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• v.12 no.4
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• pp.55-69
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• 2007

The purpose of this study was to perform a clinical test using ez NANOsence II RGP contact lenses for the effects of visual acuity and cornea on subjects with abnormal refraction status. One hundred twenty one adults (twenty nine males, ninety two females, range = 17 to 43, mean = 22.86) were recorded. The subject's history including, the symptoms from previous lens wear, were studied. The subjects were observed, both pre and post lens wear, for any symptoms and signs of change of the eye. The Visual acuity and the binocular status were tested at the far distance using the contact lens. The refraction test was performed on the naked eye using the objective method (Topcon KR-8100, Japan). The Stereopsis test was performed at the near distance after contact lens wear by the Titmus fly (Stereo Optical Co., U.S.A) and TNO (TECH, The netherlands). The contrast sensitivity diagnosis was performed at 1m distance after contact lens wear by the contrast sensitivity chart (pelli-Robertson, USA). The corneal topography was analyzed on the naked eye after lens wear by ORB scan (Bausch Lomb, U.S.A.). The ultra structure of surface on the contact lens was observed using SEM (JMS-5800, Japan). The chemical component's of the contact lens was analyzed by EDS program. The results of this study were as follows: 1. The longer of contact lens wear period, The subjects have acquired the most improved visual function. 2. Subjects had experienced few side effects wearing the contact lenses. 3. The lenses were easy to use by the subjects. 4. The longer of contact lens wear period, the power of cornea had more decrease. but the base curve of cornea had more increase and corneal astigmatism was decrease (p<0.01). Also, the thickness of corneal center was few decrease. 5. Longer periods of using the contact lens showed stereopsis and contrast sensitivity at more normal values. 6 The corneal topographical after lens wear showed most subjects with similar morphology for different wear periods. 7. The surface ultrastructure of the new and used contact lens was the similar fine shape. 8. The chemical component's of in the new and used contact appeared to have similar results. In conclusion, this study showed that the surface ultrastructure and chemical component's of the new and used contact lens are similar. In addition, the subjects had improved the quality of vision and few experienced any side effects during long periods of contact lens wear. Also they have decrease of corneal astigmatism during the long period of lens wear. Our test has showed that the chemical composition and fine structure of contact lens have related to the visual function on contact lens wearer. In this paper, we suggested that ez NANOsence II RGP contact lenses had a moderate effect for correcting vision of abnormal refraction eye.

• Journal of Animal Science and Technology
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• v.52 no.5
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• pp.427-434
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• 2010

This study was conducted to investigate the growth performance and meat quality improvement according to castration, optimal feeding management and ruminally protected amino acid-enriched fatty acid (RPAAFA) for the unselected Hanwoo bulls in the performance test. Bulls were castrated at approximately 14 months of age. Sixteen Hanwoo steers, 15 months of age and weighing $412.9{\pm}24.9kg$, were distributed into 2 groups. Steers were fed a basal diet supplemented with RPAAFA at 0 g (control) or 100 g (treatment), respectively for 12 months. Steers were slaughtered at 27 months of age. Average daily gain for treatment tended to be higher (p=0.10) than that of control, whereas feed conversion ratio tended to be lower (p=0.07) in treatment than in control. The supplementation of RPAAFA did not affect rib eye area, back fat thickness, meat color, fat color, texture and maturity. The appearance rates of yield 'A' grade and high quality grade ($1^{++}$, $1^+$ and 1) were higher in treatment than in control. The content of moisture, fat, protein and ash in longissimus muscles were similar between control and treatment. The supplementation of RPAAFA did not affect water-holding capacity, oxidation and reduction potential, myoglobin and fatty acid contents in longissimus muscles. Thus, present results indicate that castration, optimal feeding management and RPAAFA may be recommended for improving growth performance and quality grade of the unselected Hanwoo bulls in the performance test.

• Journal of Animal Science and Technology
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• v.51 no.4
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• pp.295-306
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• 2009

This experiment was conducted to investigate the effects of dietary calcium (Ca) and vitamin $D_3$ metabolite on eggshell quality and hatching egg production in aged egg-type breeder hens. A total of five hundred and forty 60-week-old Hy-Line Brown breeder hens were randomly allocated to nine treatments in a $3\times3$ factorial design to determine the effects of dietary Ca levels (3.3, 3.9, and 4.5%), combined with three levels of 25-hydroxycholecalciferol [25-$(OH)D_3$ 0, 75, and $150{\mu}g/kg$], on eggshell quality and egg production for 10 weeks. There were significant Ca and 25-$(OH)D_3$ effects (P<0.01) on egg production rate. There was a linear (P<0.01) increase in eggshell strength and thickness with increasing dietary Ca and 25-$(OH)D_3$ levels. Dietary 25-$(OH)D_3$ had a significant effect (P<0.05) on hatchability of egg although fertility was not influenced by dietarylevels of Ca and 25-$(OH)D_3$. Dietary Ca levels affected Ca content in tibia (P<0.05). These results indicated that relatively high levels of dietary Ca in combination with 25-$(OH)D_3$ had a beneficial effect on improving eggshell quality and reproductive performance in aged egg-type breeder hens.

• Nuclear Engineering and Technology
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• v.39 no.5
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• pp.603-616
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• 2007

Roy Huddle, having invented the coated particle in Harwell 1957, stated in the early 1970s that we know now everything about particles and coatings and should be going over to deal with other problems. This was on the occasion of the Dragon fuel performance information meeting London 1973: How wrong a genius be! It took until 1978 that really good particles were made in Germany, then during the Japanese HTTR production in the 1990s and finally the Chinese 2000-2001 campaign for HTR-10. Here, we present a review of history and present status. Today, good fuel is measured by different standards from the seventies: where $9*10^{-4}$ initial free heavy metal fraction was typical for early AVR carbide fuel and $3*10^{-4}$ initial free heavy metal fraction was acceptable for oxide fuel in THTR, we insist on values more than an order of magnitude below this value today. Half a percent of particle failure at the end-of-irradiation, another ancient standard, is not even acceptable today, even for the most severe accidents. While legislation and licensing has not changed, one of the reasons we insist on these improvements is the preference for passive systems rather than active controls of earlier times. After renewed HTGR interest, we are reporting about the start of new or reactivated coated particle work in several parts of the world, considering the aspects of designs/ traditional and new materials, manufacturing technologies/ quality control quality assurance, irradiation and accident performance, modeling and performance predictions, and fuel cycle aspects and spent fuel treatment. In very general terms, the coated particle should be strong, reliable, retentive, and affordable. These properties have to be quantified and will be eventually optimized for a specific application system. Results obtained so far indicate that the same particle can be used for steam cycle applications with $700-750^{\circ}C$ helium coolant gas exit, for gas turbine applications at $850-900^{\circ}C$ and for process heat/hydrogen generation applications with $950^{\circ}C$ outlet temperatures. There is a clear set of standards for modem high quality fuel in terms of low levels of heavy metal contamination, manufacture-induced particle defects during fuel body and fuel element making, irradiation/accident induced particle failures and limits on fission product release from intact particles. While gas-cooled reactor design is still open-ended with blocks for the prismatic and spherical fuel elements for the pebble-bed design, there is near worldwide agreement on high quality fuel: a $500{\mu}m$ diameter $UO_2$ kernel of 10% enrichment is surrounded by a $100{\mu}m$ thick sacrificial buffer layer to be followed by a dense inner pyrocarbon layer, a high quality silicon carbide layer of $35{\mu}m$ thickness and theoretical density and another outer pyrocarbon layer. Good performance has been demonstrated both under operational and under accident conditions, i.e. to 10% FIMA and maximum $1600^{\circ}C$ afterwards. And it is the wide-ranging demonstration experience that makes this particle superior. Recommendations are made for further work: 1. Generation of data for presently manufactured materials, e.g. SiC strength and strength distribution, PyC creep and shrinkage and many more material data sets. 2. Renewed start of irradiation and accident testing of modem coated particle fuel. 3. Analysis of existing and newly created data with a view to demonstrate satisfactory performance at burnups beyond 10% FIMA and complete fission product retention even in accidents that go beyond $1600^{\circ}C$ for a short period of time. This work should proceed at both national and international level.

• Journal of Life Science
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• v.24 no.8
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• pp.851-859
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• 2014

The present study was designed to investigate whether ethanol extracts of Sophora flavescens (GS), Glycyrrhiza uralensis (GC), Dictamnus dasycarpus (BSP), and their mixtures (GGB-1, -2, -3, and -4) inhibit 1-chloro-2,4-dinitrobenzene (DNCB)-induced atopic dermatitis (AD) in a mouse model. DNCB was topically applied on the dorsal surface of Balb/c mice to induce AD-like skin lesions. The pathological phenotypes of AD, such as erythema, ear thickness, edema, scabs, and discharge, were significantly decreased in the GGB (DNCB + GS:GC:BSP = 3:1:1 mixture)-1-treated groups compared with the other treated groups. The weight of the spleen in immune organs was significantly decreased in the GGB-1-treated groups, whereas the weight of the liver in a control group was similar to that of the groups treated with the samples. Furthermore, toluidine blue staining analysis, a method used to specifically identify mast cells, showed that master cell infiltration into the dermis of the GGB-1-treated group was significantly decreased. The immunoglobulin E concentration was lower in the GGB-1-treated group. In addition, the levels of inflammatory cytokines (interferon-${\gamma}$, interleukin-1, 4, 5, 6, and 13, $1{\beta}$, and tumor necrosis factor-${\alpha}$) were also significantly reduced in the GGB-1-treated group. Taken together, these results suggest that a mixture of GS, GC, and BSP in a proportion of 3:1:1 (GGB-1) may contribute to the relief of AD symptoms and may be considered an excellent candidate for an AD therapeutic drug.

• Journal of Animal Science and Technology
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• v.46 no.5
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• pp.811-820
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• 2004

Objectives of this study was to determine the comparisons of physico-chemical characteristics in crossbred pigs(Korean native breed ${\times}$ Landrace breed) by feeding periods. A total of 150 pigs were sampled from commercial farm, and assigned into three treatedrnents. Feeding peirods of Tl, T2 and T3 were below 200 days, 220-220 days, over 220 days, respectively. Live weight, carcass weight and backfat thickness were significantly(P<0.05) increased with feeding period increased, and final grade score have significantly(P<0.05) lower when feeding period was increased. pH and water content were significantly(P<0.05) lower when feeding period was increased(over 220days). However, intramuscular fat have no significantly different among the treatments. $L^* and b^* were significantly(P<0.05) lower and a^*$ was significantly higher(P<0.05) when feeding period increased. Cooking loss was higher in the order of Tl > T3 > T2. Shear force values was significantly(P<0.05) decreased by feed period increase. In fatty acids, myristic acid, palmitic acid, stearic acid and saturated fatty acid(SFA) in T2 were significantly(P<0.05) lower in T2, whereas linolenic acid, unsaturated fatty acid(UFA), essential fatty acid(EFA), UFA/SFA and EFA/SFA were significantly higher in T2 compared with other treatment. However palmitoleic acid and arachidonic acid were no significantly different with feeding periods. As a result of this study, crossbred pigs was increased live weight and carcass weight with feeding periods. and improved meat color and tenderness with feeding periods. However, final grade score was decreased with feeding periods