• KOREAN JOURNAL OF CROP SCIENCE
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• v.37 no.5
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• pp.405-412
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• 1992

Growth characters of dry seeded paddy rice was studied at different levels of nitrogen(N) split application (basal : immediately after irrigation : 2 weeks after irrigation: 25 days before heading: heading stage with 10 : 20 : 30 : 20 : 20%, 20 : 30 : 20 : 20 : 10%, 30 : 40 : 0 : 20 : 10%, and 100% basal of slow release urea) in tillage and no-tillage systems. On May 17 in 1990, 6kg /10a of dry seeds of a breeding line of Milyang 95 was broadcasted and covered with a power tiller. Between tillage and no-tillage systems yield and its components, lodging related characteristics, and contents of cellulose, hemicellulose and lignin of culm base were similar. Leaf area index at heading stage was higher in tillage, but lodging index was lower compared with those in no-tillage plot. Culm length, effective tiller ratio, culm base weight, 1000-grain weight, harvest index in slow release N applied plot were higher compared with those in other N treatments. Grain yield of rice among levels of N split applications was similar in tillage, but it was higher in slow release N applied plot in no-tillage if 1kg /10a of additional N was applied as urea at panicle formation stage. At early growth stage N concentration and N uptake were lower in the slow release N applied plot, but higher after heading stage compared with other N treatments. The number of tillers was lowest in slow release N applied plot during the tillering stage, but the number of panicles per hill was similar to other N treatments.

• Journal of the Korean Society of Radiology
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• v.9 no.5
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• pp.295-300
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• 2015

There are various type of particle accelerators such as Kyoungju 100-MeV proton beam accelerator in Korea. And Korea plans to build large particle accelerator such as heavy ion accelerator and 4th generation light source facility. The accelerated high energy particles of these facility produce 2nd neutron after nuclear reaction with target materials. And then these 2nd neutron activate structural materials and surrounding environment. Accordingly, it is important to consider the activation and shielding calculation on design of facility for safety operation. In this study, we tried to calculate and compare the neutron flux from the interaction $^{la}150$ beam with target material(Cu) according to thickness of iron and concrete shielding material by MCNPX 2.7 with nuclear library JENDL/HE 07and la150. To verify the properties of nuclear library, we compared computational results with experimental value. These results can be used for dose evaluation technology in planning of the shielding of large particle accelerator.

• Journal of the Korean Society of Radiology
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• v.6 no.5
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• pp.403-408
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• 2012

Prompt gamma ray from the natural Indium sample was measured by using an assembly of BGO($Bi_4Ge_3O_{12}$) scintillation detectors in the neutron energy region from 1 to 300 eV. The assembly was composed of pieces of BGO. The spectrometer was composed geometrically as total energy absorption detector. 46-MeV electron linear accelerator which is located at Research Reactor Institute, Kyoto University used for neutron sources from photonuclear reaction. The measurement of the neutron capture resonances was performed to below neutron energy 1 keV, because of strong X-ray effect from photonuclear reaction in Ta target and short distance from the target to an assembly of detector. The distance of neutron flight path is $12.7{\pm}0.02m$. The large neutron capture resonances were measured from 1 to 400 eV. The energy in the capture resonance was compared with the evaluated values. The large resonances were seen in the present measurement. General agreement can be seen between the present measurement and the previous evaluated data in relevant energy region. In the present study, we measured the continues resonance structure above 1 keV neutron energy region. 91.49 eV new neutron capture resonance was found in present measurement.

• The Journal of the Korea Contents Association
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• v.7 no.12
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• pp.139-144
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• 2007

Radiotherapy which is the most effective for orbit lymphoma has been used increasingly due to the increase of orbit or ocular adnexal tumor patients. Curative effects and convalescence have been being more satisfied thanks to remarkable development of cancer chemotherapy and medical treatments, but side effects such as cataract, dry eye and retinopathy still break out. Thus, in this study, a Lens Shielding Device (LSD hereafter) was designed to prevent occurring of cataract due to radiation therapy for orbit lymphoma and its efficacy through dosimetry were evaluated. And in this paper, its manufacturing process was also explained. LSD is composed of a cover body covering the lens and a side fixing part supporting the cover body. To measure radiation, the patient therapy conditions were simulated and the measurement of the radiation was conducted with Thermo Luminescence Detector (TLD) and Markus chamber. The average TLD value was 5.7% and the TLD value and Markus chamber value were acquired as 4.2% and 5.1% respectively at 6 mm depth where zero lens center was located. Only 1.5Gy ($300Gy{\times}\;5%$) or 5% of total 30Gy with 9 MeV electron beam is estimated to affect on patient's lens. That is smaller dose than the threshold value of cataract (2GY) or the value (5Gy) that was reported to cause cataract in clinical conditions. Thus, these findings suggest that LSD be very useful for prevention of cataract during radiotherapy for malignant lymphoma of orbit and ocular adnexa. Furthermore, it might be possible to reduce patient's discomfort caused by alien substances and to make it easier to fix the device with customized manufacturing manners.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.4
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• pp.55-63
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• 2020

This study investigates the mechanical properties and reaction products of activated slag pastes depending on gypsum presence and calcium carbonate addition in terms of compressive strength tests and synchrotron X-ray diffraction. The chemicals of CaO and NaOH are used as activators with different two dosages. The reaction of CaO-activated slag without gypsum just accelerated by addition of calcium carbonate at early ages, but no improvement was observed at later ages. On the other hand, the mechanical properties of CaO-activated slag pastes with gypsum were improved with calcium carbonate, enhancing the stability of ettringite. The variation of mechanical properties of NaOH-activated slag pastes was negligible depending on calcium carbonate addition in case of no gypsum. The addition of calcium carbonate into NaOH-activated slag pastes with gypsum deteriorated its mechanical properties due to the ion competition between CO₃^2- ions and SO₃^2- ions, decreasing crystallinity of reaction products.

• Journal of the Korean Society of Safety
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• v.25 no.6
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• pp.34-39
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• 2010

The purpose of this study is to suggest objective evaluation model as a plan to utilize as opportunity in establishing judgment standard of mutual inspection criteria and to upgrade inspection ability by reviewing and analyzing level of danger and importance in advance based on inspection results of inspection institutions regarding tower cranes used in construction fields. Tower crane is a mechanical device transporting construction supplies and heavy materials to places over 20~150M high from the ground for the period ranging from a short time of 2~3 months to two years after being installed in construction sites in vicinity of buildings or structures and is an important facility indispensable for construction sites. However, since use period after installation is short and professional technical ability of technicians working on-site about of tower crane is poor, systematic and quantitative safety management is not carried out As a part of researches on procedure of RBI(Risk Based Inspection) possible to apply to Knowledge Based System based on knowledge and experiences of experts as well as to tower cranes for solving these problems, quantitative RPN(Risk Priority Number) was applied to RPN utilizing technique of FMEA(Failure Mode and Effect Analyses). When general RBI 80/20 Rule was applied parts with high level of risks were found out as wire rope, hoist up/down safety device, reduction gear, and etc. However, since there are still many insufficient parts as risk analyses of tower crane were not established, it is necessary for experts with sufficient experiences and knowledge to supplement active RBI techniques and continuous researches on tower cranes by sharing and setting up data base of important information with this study as a starting point.

• Progress in Medical Physics
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• v.13 no.3
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• pp.109-113
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• 2002

In recent years, the radiotherapy equipment has become much more sophisticated, and with the complication comes an increased set of quality assurance (QA) responsibilities. Today's computer controlled linear accelerator requiring QA of not only the radiation integrity, but also the mechanical accuracy of the linear accelerator. The existing QA sheets are adequate for acceptance testing and commissioning but those sheets are somewhat descriptive form for routine QA. establishing the QA sheets for a facility are more efficient if the sheets could estimate the long-term stability for the result of QA. We are going to develope new prototype of mechanical QA sheet to visualize and to verify long-term stability of mechanical QA for clinical linear accelerator. The items included in mechanical QA sheet were 1) gantry rotation, 2) collimator rotation, 3) couch rotation, 4) optical distance indicator (ODI), and 5) laser alignment. We compared new prototype sheet with conventional sheet for several hospitals in Korea for those items. The QA acceptance criteria in this study mainly followed published recommendations. The contents of test for mechanical QA are the following. Confirm that the digital and/or mechanical gantry angle readouts are correct. Verify that digital and/or mechanical readouts of collimator angle agree with the true angle, as determined with the protractor. Measure the light field using a graph paper and compare with the digital readouts. Confirm digital readout accuracy. Verify that the sagittal laser, the left and right lasers, and the ceiling laser intersect at the isocenter. In the design of new QA sheet, we emphasized the representation of the long-term stability of mechanical QA by using Excel program. By using the new prototype QA sheet, we simplified and visualized the mechanical QA process, and could estimate the long-term stability of mechanical error of linear accelerator.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.6
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• pp.1149-1158
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• 2000

A radioisotope tracer experiment was carried out in the submerged fixed bioreactor of a dye wastewater treatment facility to evaluate the flow behaviors in the 6 compartments of the reactor and to find any possible factors which may affect to the efficiency of the process. Approximately 20mCi of $^{131}I$ was injected into the system as a tracer and 8 radiation detectors were placed in the 6 compartments and at the inlet and the outlet of the system to measure the change of the tracer concentration with time. Using the Perfect Mixers in Series Model the measured data were analyzed to calculate the mean residence time and the characteristic parameters of the flow in the system. The mean residence time of the system was calculated as 17 hours which is 76% of the designed MRT(22.3hr). Among the 6 compartments, the first compartment doesn't show the characteristic of perfect mixer, whereas, the other 5 compartments are working as perfect mixers. The output response of the first compartment is fit well with the simulated output of a model which consists of a perfect mixer with an exchange volume. It indicates that a quarter of the tank volume is working as a dead volume or an exchange volume. From the measured residence time distributions in each compartment, the appropriate sampling times after the change of operational condition of the electron beam accelerator were evaluated.

• Economic and Environmental Geology
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• v.42 no.5
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• pp.509-512
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• 2009

Powder diffraction patterns of the zeolite mesolite ($Na_{5.33}Ca_{5.33}Al_{16}Si_{24}O_{80}{\cdot}21.33H_2O$), with a natrolite framework topology were measured as a function of pressure up to 5.0 GPa using a diamond-anvil cell and a $200{\mu}m$-focused monochromatic synchrotron X-ray. Under the hydrostatic conditions mediated by pore-penetrating alcohol and water mixture, the elastic behavior of mesolite is characterized by continuous volume expansion between ca. 0.5 and 1.5 GPa, which results from expansion in the ab-plane and contraction along the c-axis. Subsequent to this anomalous behavior, changes in the powder diffraction patterns suggest possible reentrant order-disorder transition. The ordered layers of sodium- and calcium-containing channels in a 1:2 ratio along the b-axis attribute to the $3b_{natrolite}$ cell below 1.5 GPa. When the volume expansion is completed above 1.5 GPa, such characteristic ordering reflections disappear and the $b_{natrolite}$ cell persists with marginal volume contraction up to ca. 2.5 GPa. Further increase in pressure leads to progressive volume contraction and appears to generate another set of superlattice reflections in the $3c_{natrolite}$ cell. This suggests that mesolite in the pressure-induced hydration state experiences order-disorder-order transition involving the motions of sodium and calcium cations either through cross-channel diffusion or within the respective channels.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.9
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• pp.1027-1032
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• 2012

Two types of very small multiplying gears and arrays have been developed for new dental hand-pieces, and the increased speed ratios, modules, number of teeth, gear diameters, and gear types were calculated based on the dynamics of the machinery. The contacting and bending strengths were evaluated for gear teeth with two design concepts using AGMA equations and finite element analyses, and the contacting stresses on teeth with and without DLC (diamond-like-carbon) coating layers were calculated. Fatigue and tension tests were performed to obtain an S-N curve, the Young's modulus, and the strength of the gear material, and these were utilized in the analyses. Slightly larger stresses were found for 2-axis-type gears than for other types of gears, and the S-N curves showed that a gear lifetime of 109 cycles was satisfied. The contacting stresses in gears coated with DLC were reduced by 30%. A new prototype model of a hand-piece with small gears was successfully fabricated and tested.