• Korean Journal of Environmental Agriculture
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• v.15 no.2
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• pp.198-206
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• 1996

Leaching of $^{54}Mn$, $^{60}Co$, $^{85}Sr$ and $^{137}Cs$ in paddy soil was studied using lysimeter cultures in a greenhouse. The radionuclides were applied to the water surfaces shortly before transplanting and five different times between transplanting and harvest. Fertilizer KCl and slaked lime were added simultaneously in the rate of 83kg and 200kg, respectively, per l0a following the first application after transplanting. Percolating water was sampled until two days before harvest. Concentrations of the radionuclides in percolating water decreased in the order of $^{85}Sr$ > $^{54}Mn$ > $^{60}Co$ > $^{137}Cs$ on the whole. Time taken to reach the maximum was the shortest for $^{137}Cs$(< one week) and the longest for $^{54}Mn$ and $^{85}Sr$. Six days' water dropping started 47 days after transplanting reduced the concentrations of $^{54}Mn$, $^{60}Co$, $^{85}Sr$ and $^{137}Cs$ by factors of 30-180, 3-75, 2-4 and 3-6, respectively, depending on the application time. After the significant decrease, $^{54}Mn$ concentration tended to gradually increase but $^{137}Cs$ did to the contrary Percent leaching varied 0.09-6.2% for $^{54}Mn$, 0.009-0.9% for $^{60}Co$, 1.4-14.4% for $^{85}Sr$ and 0.002-0.06% for $^{137}Cs$, with the application time. The highest leaching came from the application at 40 days after transplanting for all the radionuclides. The addition of KCl and lime increased percent leaching of the radionuclides by factors of 9, 85, 4 and 9, respectively.

• Journal of Physiology & Pathology in Korean Medicine
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• v.16 no.2
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• pp.373-379
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• 2002

This paper was the design of aerosol generator for inhalation toxicology study of lead and evaluation with real time monitoring, and applied several engineering methodology to classical aerosol generator to cope with it's disadvantages. According to the testing conditions, source temperature 50℃ and inlet-duct band heater temperature 150℃, aerosol generation results for sodium chloride and lead acetate were as followings: CPM(Count Per Minute) for Sodium chloride that used for the testing material in aerosol generation and inhalation system was decreased in the 2nd and the 3rd hour's serial trials, but CVs(coefficient of variation) were maintained within 10%. CPMs for 5 and 2.5 gram of lead acetate that used for aerosol generation and inhalation exposure of lead showed similar results because of the sedimentation of lead acetate on piezoelectric crystal with time. For that reason, heating and mixing of nebulizing solution will be needed to generate lead aerosol with stable profile and maximum generation efficiency. Fluctuations of 10 and 5 gram lead acetate were low but 2.5gram was high. However, CVs for 10, 5, and 2.5gram lead acetate were within 10%. Considering the theoretical efficiencies for sodium chloride and lead acetate, 5gram sodium chloride and 2.5gram lead acetate were appropriate choice. Aerosol generation characteristics for two materials with 1 hour interval were different with respect to the fluctuation of CPM and the decrease to 10gram in it's material. For that reason, sodium chloride can not be used to estimate the aerosol generation and it's related parts for lead acetate. According to the testing conditions, source temperature 20, 50, 70℃, and inlet-duct band heater temperature 20, 50, 100, 150, 200℃, aerosol generation results for sodium chloride and lead acetate were as followings: Excluding inlet-duct band temperature 200℃, maximum CPM for sodium chloride was manifested in source temperature 70℃ with each inlet-duct band temperature conditions. We suggest that this condition was the optimum in the design of aerosol generator, inhalation system, and the testing. Maximum CPMs for 10, 5, and 2.5gram sodium chloride were from source temperature 70℃ and inlet-duct band temperature 20℃. Excluding inlet-duct band temperature 50, 200℃, maximum CPMs for lead acetate were indicated in source temperature 50℃ with each inlet-duct band temperature conditions. We suggest that this condition was the optimum in the design of aerosol generator, inhalation system, and the testing for lead inhalation study. Source and inlet-duct band temperatures for 10, 5, 2.5gram lead acetate were 50 and 100℃, 50 and 100℃, 50 and 150℃, respectively. In conclusion, considering above 2 paragraphs of results for aerosol generation, 5gram efficiencies for sodium chloride, lead acetate were higher than 2.5gram's. If inlet-duct band temperature was same, aerosol generation was increased with increase of source temperature. To get maximum aerosol generation will be the conditions that set the appropriate inlet-duel band temperature for each materials and increase the source temperature.

• Journal of radiological science and technology
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• v.37 no.1
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• pp.7-14
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• 2014

By using a Chest Phantom(DUKE Phantom) focusing on dose reduction of diagnostic radiation field with the most use of artificial radiation, and attempt to reduce radiation dose studies technical radiation. Publisher of the main user of the X-ray Radiological technologists, Examine the effect of reducing the radiation dose to apply additional filtering of the X-ray generator. In order to understand the organ dose and effective dose by using the PC-Based Monte Carlo Program(PCXMC) Program, the patient receives, was carried out this research. In this experiment, by applying a complex filter using a copper and Al(aluminum,13) and filtered single of using only aluminum with the condition set, and measures the number of the disk of copper indicated by DUKE Phantom. The combination of the composite filtration and filtration of a single number of the disk of the copper is the same, with the PCXMC 2.0. Program looking combination of additional filtration fewest absorbed dose was calculated effective dose and organ dose. Although depends on the use mAs, The 80 kVp AP projection conditions, it is possible to reduce the effective amount of about 84 % from about 30 % to a maximum at least. The 120 kVp PA projection conditions, it is possible to reduce the effective amount of about 71 % from about 41 % to a maximum of at least. The organ dose, dose reduction rate was different in each organ, but it showed a decrease of dose rate of 30 % to up 100 % at least. Additional filtration was used on the imaging conditions throughout the study. There was no change in terms of video quality at low doses. It was found that using the DUKE Phantom and PCXMC 2.0 Program were suitable to calculate the effect of reducing the effective dose and organ dose.

• The Journal of Korean Academy of Prosthodontics
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• v.48 no.4
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• pp.287-293
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• 2010

Purpose: This study evaluated the effect of polishing techniques on surface roughness of polymethyl methacrylate (PMMA), as well as the influence of light-cured surface glaze and subsequent brushing on surface roughness. Materials and methods: A total of 60 PMMA specimens ($10{\times}10{\times}5\;mm$) were made and then divided into 6 groups of 10 each according to the polymerization methods (under pressure or atmosphere) and the surface polishing methods (mechanical or chemical polishing) including 2 control groups. The mechanical polishing was performed with the carbide denture bur, rubber points and then pumice and lathe wheel. The chemical polishing was performed by applying a light-cured surface glaze ($Plaquit^{(R)}$; Dreve-Dentamid GmbH). Accura $2000^{(R)}$, a non-contact, non-destructive, optical 3-dimensional surface analysis system, was used to measure the surface roughness (Ra) and 3-dimensional images were acquired. The surface roughness was again measured after ultrasonic tooth brushing in order to evaluate the influence of brushing on the surface roughness. The statistical analysis was performed with Mann-Whitney test and t-test using a 95% level of confidence. Results: The chemically polished group showed a statistically lower mean surface roughness in comparison to the mechanically polished group (P = .0045) and the specimens polymerized under the atmospheric pressure presented a more significant difference (P = .0138). After brushing, all of the groups, except the mechanically polished group, presented rougher surfaces and showed no statistically significant differences between groups. Conclusion: Although the surface roughness increased after brushing, the chemical polishing technique presented an improved surface condition in comparison to the mechanical polishing technique.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.3
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• pp.9-15
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• 2016

We investigated >$50-{\mu}m$ marine planktonic organisms (mainly zooplankton) using a bongo net in Masan Bay and Jangmok Bay in order to harvest 75% of natural communities based on Phase-II approval regulations by the United States Coast Guard (USCG). The concentrated volume (in 1 ton) and abundance of zooplankton were $1.8{\times}10^7ind.ton^{-1}$ and $2.3{\times}10^7ind.ton^{-1}$, and their survival rates were 82.6% and 80.1%, respectively. The community structure in Jangmok Bay was similar to that in Masan Bay, and dominant species were adult and immature groups (stage IV) of genus Acartia. Harvested populations were inoculated in a 500-ton test tank. Although the population abundances were $6.0{\times}10^4ind.ton^{-1}$ for both bay samples, the mortality rates were higher in the Masan Bay population (32%) than the Jangmok Bay population (20%). We considered the reason to be that there were 30% more immature individuals of Acartia from Masan Bay than from Jangmok Bay. The younger population may have been greatly stressed by the moving process and netting gear. After applying a Ballast Water Treatment System (BWTS) using a sample form Jangmok Bay, the mortality rates in the treatment groups were found to be 100% after 0 days and 5 days, implying that the BWTS worked well. During the winter season, the zooplankton concentration method alone did not easily satisfy the approval standards of USCG Phase II (> $10{\times}10^4ind.ton^{-1}$ in the 500 ton tank). Increasing the netting frequency and additional fishing boats may be helpful in meeting the USCG Phase II biological criteria.

• Journal of radiological science and technology
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• v.30 no.2
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• pp.105-111
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• 2007

This study is to calculate the proper angle for the optimal image of PNS Water's view on children, comparing and analyzing the PNS Water's projection angles between children and adults at every age. This study randomly selected 50 patients who visited the Medical Center from January to May in 2005, and examined the incidence path of central ray, taking a PNS Water's and skull trans-Lat. view in Water's filming position while attaching a lead ball mark on the Orbit, EAM, and acanthion of the patients's skull. And then, we calculated the incidence angles(Angle A) of the line connected from OML and the petrous ridge to the inferior margin of maxilla on general(random) patients's skull image, following the incidence path of central ray. Finally, we analyzed two pieces of the graphs at ages, developing out the patients' ideal images at PNS Water's filming position taken by a digital camera, and calculating the angle(Angle B) between OML and IP(Image Plate). The angle between OML and IP is about $43^{\circ} in 4-years-old children, which is higher than $37^{\circ}, as age increases the angle decreases, it goes to $37^{\circ} around 30 years of age. That is similar result to maxillary growth period. We can get better quality of Water's image for children when taking the PNS Water's view if we change the projection angles, considering maxillary growth for patients in every age stage.

• Journal of Bio-Environment Control
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• v.20 no.2
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• pp.93-100
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• 2011

Maintenance of adequate soil water potential during the period of crop growth is necessary to support optimum plant growth and yields. A better understanding of soil water movement within and below the rooting zone can facilitate optimal irrigation scheduling aimed at minimizing the adverse effects of water stress on crop growth and development and the leaching of water below the root zone which can have adverse environmental effects. The objective of this study was to evaluate the feasibility of using a portable irrigation controller with an Watermark sensor for the cultivation of drip-irrigated vegetable crops in a greenhouse. The control capability of the irrigation controller for a soil water potential of -20 kPa was evaluated under summer conditions by cultivating 45-day-old tomato plants grown in three differently textured soils (sandy loam, loam, and loamy sands). Water contents through each soil profile were continuously monitored using three Sentek probes, each consisting of three capacitance sensors at 10, 20, and 30 cm depths. Even though a repeatable cycling of soil water potential occurred for the potential treatment, the lower limit of the Watermark (about 0 kPa) obtained in this study presented a limitation of using the Watermark sensor for optimal irrigation of tomato plants where -20 kPa was used as a point for triggering irrigations. This problem might be related to the slow response time and inadequate soil-sensor interface of the Watermark sensor as compared to a porous and ceramic cup-based tensiometer with a sensitive pressure transducer. In addition, the irrigation time of 50 to 60 min at each of the irrigation operation gave a rapid drop of the potential to zero, resulting in over irrigation of tomatoes. There were differences in water content among the three different soil types under the variable rate irrigation, showing a range of water contents of 16 to 24%, 17 to 28%, and 24 to 32% for loamy sand, sandy loam, and loam soils, respectively. The greatest rate increase in water content was observed in the top of 10 cm depth of sandy loam soil within almost 60 min from the start of irrigation.

• Investigative Magnetic Resonance Imaging
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• v.8 no.2
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• pp.94-99
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• 2004

Purpose : To investigate the signal enhancement ratio by NOE effect on in vivo $^{31}P$ MRS in human heart muscle and liver. we also evaluated the enhancement ratios of different phosphorus metabolites, which are important in 31P MRS for each organ. Materials and Methods : Ten normal subjects (M:F = 8:2, age range = 24-32 yrs) were included for in vivo $^{31}P$ MRS measurements on a 1.5 T whole-body MRI/MRS system using $^1H-^{31}P$ dual tuned surface coil. Two-dimensional Chemical Shift Imaging (2D CSI) pulse sequence for $^{31}P$ MRS was employed in all $^{31}P$ MRS measurements. First, $^{31}P$ MRS performed without NOE effect and then the same 2D CSI data acquisitions were repeated with NOE effect. After postprocessing the MRS raw data in the time domain, the signal enhancements in percent were estimated from the major metabolites. Results : The calculated NOE enhancement for liver $^{31}P$ MRS were $\alpha-ATP\;(7\%),\;\beta-ATP\;(9\%),\;\gamma-ATP\;(17\%),\;Pi\;(1\%),\;PDE\;(19\%)$ and $PME\;(31\%)$. Because there is no creatine kinase activity in liver, PCr signal is absent. For cardiac $^{31}P$ MRS, whole body coil gave better scout images and thus better localization than surface coil. In $^{31}P$cardiac multi-voxel spectra, DPG signal increased from left to right according to the amount of blood included. The calculated enhancement for cardiac $^{31}P$ MRS were : $\alpha-ATP\;(12\%),\;\beta-ATP\;(19\%),\;\gamma-ATP\;(30\%),\;PCr\;(34\%),\;Pi\;(20\%),\;(PDE)\;(51\%),\;and\;DPG\;(72\%)$. Conclusion : Our results revealed that the NOE effect was more pronounced in heart muscle than in liver with different coupling to 1H spin system and thus different heteronuclear cross-relaxation.

• Journal of the Korean Society of Radiology
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• v.12 no.3
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• pp.409-415
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• 2018

The development of smart devices has brought about significant changes in daily life and one of the most significant changes is the virtual reality zone. Virtual reality is a technology that creates the illusion that a 3D high-resolution image has already been created using a display device just like it does in itself. Unrealized subjects are forced to rely on audiovisual materials, resulting in a decline in the concentration of practices and the quality of classes. It used virtual reality to develop effective teaching materials for radiology students. In order to produce a video clip bridge using virtual reality, a radiology clinic was selected to conduct two exposures from July to September 2017. The video was produced taking into account the radiology and work flow chart and filming was carried out in two separate locations : in the computerized tomography unit and in the LINAC room. Prior to filming the scenario and the filming route were checked in advance to facilitate editing of the video. Modeling and mapping was performed in a PC environment using the Window XP operating system. Using two leading virtual reality camera Gopro Hero, CC pixels were produced using a 4K UHD, Adobe, followed by an 8 megapixel resolution of $3,840{\times}2,160/4,096{\times}2,160$. Total regeneration time was performed in about 5 minutes during the production of using virtual reality to prevent vomiting and dizziness. Currently developed virtual reality radiation and educational contents are being used to secure the market and extend the promotion process to be used by various institutions. The researchers will investigate the satisfaction level of radiation and educational contents using virtual reality and carry out supplementary tasks depending on the results.

• Korean Journal of Food Science and Technology
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• v.23 no.1
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• pp.44-51
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• 1991

The thermal resistance of the important microorganisms in takju. Korean traditional turbid alcoholic beverage, was measured and optimun heating time and temperature to achieve the commercial pasteurization of these microorganisms were examined. Most of the vegetative bacterial cells in takju were destroyed by heating at over $60^{\circ}C$, except for the spore forming organisms, which did not actively grow in takju after pasteurization. The important microorganisms for the quality deterioration of pasteurized takju were then appeared to be yeast and molds, and their thermal resistances were measured. The thermal resistances of these microorganisms changed greatly depending upon the heating method. The D values of yeast in takju were 3.5 min at $65^{\circ}C$ and 0.46 min at $80^{\circ}C$ in cap-tube, and 7.1 sec at $65^{\circ}C$ and 2.3 sec at $80^{\circ}C$ in a continuous coil heat exchanger. Those of molds were 2.7 min at 65℃ and 0.25 min at $80^{\circ}C$ in cap-tube, and 3 sec at $65^{\circ}C$ and <1 sec at $80^{\circ}C$ in the coil heat exchanger. The acidity and pH did not change at $30^{\circ}C$ for two weeks after pasteurization by heating in the coil heat exchanger at $65^{\circ}C$ for 17 sec, but the viscosity increased slightly by the heat treatment. Significant differences in sensory quality, especially the formation of burnt smell and bitterness by heating takju for 12D of yeast at $70,\;80\;and\;85^{\circ}C$, respectively, were observed and this resulted in the significant reduction in overall likeness of pasteurized takju. However, when the heating temperature was fixed to $80^{\circ}C$, the overall likeness of pasteurized takju did not affected significantly by the heating time ranging from 8D to 12D of yeast. It was concluded that the optimum pasteurization condition of takju in a continuous heat exchanger was heating at $80^{circ}C$ for 23sec(10D of yeast).