• Journal of the korean academy of Pediatric Dentistry
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• v.30 no.3
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• pp.423-430
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• 2003

The teeth bleaching with bleaching agent is widely used at recent times. Until yet the exact mechanism of the bleaching agent isn't known but it is thought that is by the complex reduction-oxidation reaction of the decomposed free radical from bleaching agent through various ways. In other words, it is supposed that the teeth are whitened by agent's changing chemical structures of stain-causing materials. The purpose of this study is to exam the change of the dentinal character by bleaching agent and to evaluate the safety of this agent. For this study, after applying 10% carbamide peroxide to enamel of human premolar for 6 hours a day for 2 weeks we examined changes of surface morphology, microhardness, composition and contents of minirals in human dentin using SEM, microhardness tester, FT-Raman spectrometer and EPMA and got following results. There was no significant difference in surface morphologic change when we examined the effect of 10% carbamide peroxide which penetrated into dentin after applied on enamel surface comparing with result from specimen in distilled water No change was shown on the surface of peritubular and intertubular dentin within the nanometeric range. The microhardness between bleached teeth and teeth stored in distilled water showed no statistically significant difference FT-Raman spectra of dentin exhibited no change of the component in human dentin. Only the least change in peaks of organic and inorganic materials were detected in Raman intencity. The total content of mineral elements in dentin with no treatment, stored only in distilled water and stored in distilled water after bleaching were $98.73{\pm}1.89,\;98.56{\pm}2.11\;and\;97.47{\pm}2.51$ respectively. Also they showed no statistically significant difference. From above results, the effect of 10% carbamide peroxide bleaching on structure of dentin is very low and the results may confirm the safety of this bleaching agent.

• Journal of Radiation Protection and Research
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• v.39 no.3
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• pp.127-133
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• 2014

North Korea's uranium enrichment facility is a matter of international concern. It is of particular alarming to South Korea with regard to the security and safety of the country. This situation requires continuous monitoring of the DPRK and emergency preparedness on the part of the ROK. To assess the detectability of an undeclared uranium enrichment plant in North Korea, uranium concentrations in the air at both a short and a long distance from the enrichment facility were estimated. $UF_6$ source terms were determined by using existing information on North Korean facility and data from the operation experience of enrichment plants from other countries. Using the calculated source terms, two atmospheric dispersion models (Gaussian Plume Model and HYSPLIT models) and meteorological data were used to estimate the uranium particle concentrations from the Yongbyon enrichment facility. A maximum uranium concentration and its location are dependent upon the meteorological conditions and the height of the UF6 release point. This study showed that the maximum uranium concentration around the enrichment facility was about $1.0{\times}10^{-7}g{\cdot}m^{-3}$. The location of the maximum concentration was within about 0.4 km of the facility. It has been assumed that the uranium sample of about a few micrograms (${\mu}g$) could be obtained; and that few micrograms of uranium can be easily measured with current measurement instruments. On the contrary, a uranium concentration at a distance of more than 100 kilometers from the enrichment facility was estimated to be about $1.0{\times}10^{-13}{\sim}1.0{\times}10^{-15}g{\cdot}m^{-3}$, which is less than back-ground level. Therefore, based on the results of our paper, an air sample taken within the vicinity of the Yongbyon enrichment facility could be used to determine as to whether or not North Korea is carrying out an undeclared nuclear program. However, the air samples taken at a longer distance of a few hundred kilometers would prove difficult in detecting a clandestine nuclear activities.

• The Korean Journal of Nuclear Medicine
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• v.39 no.6
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• pp.464-472
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• 2005

Purpose: SPECT using a fan-beam collimator improves spatial resolution and sensitivity. For the reconstruction from fan-beam projections, it is necessary to implement direct fan-beam reconstruction methods without transforming the data into the parallel geometry. In this study, various fan-beam reconstruction algorithms were implemented and their performances were compared. Materials and Methods: The projector for fan-beam SPECT was implemented using a ray-tracing method. The direct reconstruction algorithms implemented for fan-beam projection data were FBP (filtered backprojection), EM (expectation maximization), OS-EM (ordered subsets EM) and MAP-EM OSL (maximum a posteriori EM using the one-step late method) with membrane and thin-plate models as priors. For comparison, the fan-beam protection data were also rebinned into the parallel data using various interpolation methods, such as the nearest neighbor, bilinear and bicubic interpolations, and reconstructed using the conventional EM algorithm for parallel data. Noiseless and noisy projection data from the digital Hoffman brain and Shepp/Logan phantoms were reconstructed using the above algorithms. The reconstructed images were compared in terms of a percent error metric. Results: for the fan-beam data with Poisson noise, the MAP-EM OSL algorithm with the thin-plate prior showed the best result in both percent error and stability. Bilinear interpolation was the most effective method for rebinning from the fan-beam to parallel geometry when the accuracy and computation load were considered. Direct fan-beam EM reconstructions were more accurate than the standard EM reconstructions obtained from rebinned parallel data. Conclusion: Direct fan-beam reconstruction algorithms were implemented, which provided significantly improved reconstructions.

• Journal of Animal Science and Technology
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• v.51 no.1
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• pp.45-52
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• 2009

This experiment was conducted to observe the effects of anaerobic cellulolytic bacteria culture (Ruminococcus flavefaciens H-20 and Fibrobactor succinogenes H-23) on in vivo ruminal fermentation characteristics in Hanwoo heifers. Four ruminally cannulated Hanwoo heifers ($221\pm7.5kg$) receiving a basal diet containing 3 kg of mixture hay (tall fescue and ochardgrass) and 2 kg of concentrate per day were in a $4\times4$ Latin square with 21-day periods. Treatments were the basal diet without the culture additive (control), the basal diet plus 50 ml/day of bacteria culture of H-20 and H-23 (1%), 150 ml/day of H-20 and H-23 (3%), and 250 ml/day of H-20 and H-23 (5%). In the whole experimental periods, ruminal pH did not differ between treatments. However, the concentration of ruminal ammonia-N was increased in the 3% treatment relative to control and the 1% treatment at 1 hr post-feeding (p<0.05). Avicelase and CMCase (carboxymethyl cellulase) activities in rumen fluid showed no significant difference among treatments. However, xylanase activity was higher in the 5% (119.49, xylose ${\mu}mol$/ml/min) than the 3% treatment (71.02, xylose ${\mu}mol$/ml/min) at 0 hr post-feeding (p<0.05). Concentrations of ruminal total VFA, acetate, propionate and valerate were unaffected by treatments, while butyrate was higher in the 3% treatment (24.48 mM) than control (15.71 mM) at 1 hr post-feeding (p<0.05). Results indicate that minimum 3% inclusion of cellulolytic bacteria cultures improved ruminal fermentation, especially ammonia-N concentration and butyric acid production.

• The Korean Journal of Nuclear Medicine Technology
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• v.20 no.2
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• pp.75-79
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• 2016

Purpose The ASAN Medical Center, Nuclear Medicine performs TSH (Thyroid stimulating hormone) and FT4 (Free Thyroxine) tests 8 times per day. Accordingly, 70 ~ 80 kit tubes are consumed every day for the measurements and the time consumed for reagent dispensing averages over 170 seconds, where the TAT (turnaround time) may be effected when the number of test samples is larger than expected. Therefore, the following test was conducted with the purpose to reduce the number of kit tubes consumed, and reduce the time for reagent dispensing. Materials and Methods The test is based on applying the same reagent for tests where the number of samples is 30 or less. The test for TSH was conducted 9 times from July $1^{st}$ 2015 to July $10^{th}$ 2015. The test for FT4 was conducted 4 times from June $18^{th}$ 2015 to June $22^{nd}$, 2015. Standard Solution No.2 (0.153 uU/mL) and No.5 (4.96 uU/mL) was selected as the two-point standards for the TSH test, and Standard Solution No.3 (0.777 ng/dL) and No.4 (2.044 ng/dL) was selected as the two-point standards for the FT4 test. 38 test samples were subject to correlation analysis. Results For TSH, the result of the normal test shows ranges of 0.20 ~ 0.37 uU/mL for Control1, 0.53 ~ 0.71 uU/mL for Control2, and 6.77 ~ 7.94uU/mL for Control3, while the result of two-point calibration curve test shows ranges of 0.18 ~ 0.27 uU/mL for Control1, 0.53 ~ 0.71 uU/mL for Control2, and 7.30 ~ 8.52 uU/mL for Control3. For FT4, the result of the normal test shows ranges of 0.85 ~ 0.94 ng/dL for Control1 and 4.23 ~ 4.57 ng/dL for Control2, while the result of two-point calibration curve test shows ranges of 0.61 ~ 0.75 ng/dL for Control1 and 3.88 ~ 5.71 ng/dL for Control2. For TSH, the CV% of the normal test for Control1, Control2 and Control3 are 10.5, 3.3 and 3.6 respectively, while the CV% of the two-point calibration curve test for Control1 and Control1 are 12.4, 8.2 and 5.1 respectively. The result shows an outstanding correlation of TSH: y = 0.9985x - 0.0459 $R^2=0.9986$. For FT4, the CV% of the normal test for Control1 and Control2 are 0.70 and 0.71 respectively, while the CV% of the two-point calibration curve test for Control1 and Control1 are 8.7 and 16.2 respectively. The result shows an outstanding correlation of FT4: y = 1.2674x - 0.1133 $R^2=0.9824$. Conclusion The two-point calibration curve can be efficiently applied for TSH in cases where the number of test samples is not large, since the number of samples to be re-tested increases when the result is abnormal from the calibration curve. The two-point calibration curve test should not be applied for FT4 where the results do not consistently comply with the quality assessment range. Depending on how the two-point calibration curve is applied, up to 5 test tubes can be conserved per test, and the reduced time for reagent dispensing is anticipated to have a positive effect on the TAT (turnaround time).

• Pediatric Infection and Vaccine
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• v.8 no.2
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• pp.175-180
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• 2001

Purpose : Recently in Korea since 1998, 2TU has been used instead of 5TU, which caused a confusion in interpreting tuberculin skin tests. We compared the tuberculin skin reaction to PPD(purified protein derivatives) 1TU, 2TU and 5TU. Methods : We studied tuberculin skin reaction to PPD 1TU, 2TU and 5TU on 92 infants who were vaccinated with percutaneous multiple puncture BCG vaccine(Tokyo 172 strain, Japan BCG Laboratory Co.) in neonatal period. Diameters of indurations were measured in millimeters 48~72 hours after the intradermal injection of PPD 1TU, 2TU and 5TU. Results : Among 92 infants(male : 56, female : 36), 1TU was used on 31 infants, 2TU on 31 infants and 5TU on 30 infants for tuberculin skin test. The mean diameter of induration for PPD 1TU, 2TU and 5TU were $5.7{\pm}4.2mm$, $7.1{\pm}3.7mm$, and $9.2{\pm}4.2mm$, respectively. There was no statistical difference in mean diameter of induration between 1TU and 2TU. However, when tested with 5TU, the diameter of induration was significantly larger than those of PPD 1TU and 2TU(P<0.05). Six subjects(19.4%) tested with 1TU, 9 subjects(29%) tested with 2TU and 16 subjects(53.3%) tested with 5TU had diameter of 10 mm or more. There was no statistical difference between 1TU and 2TU but for 5TU, number of subjects with diameter of 10 mm or more was significantly higher than PPD 1TU and 2TU(P<0.05). Number of subjects with induration diameter of 5 mm or more for 1TU, 2TU and 5TU was 19(61.3%), 22(71.0%) and 26(86.7%), respectively. However, there was no statistical difference. Conclusion : A new standard criteria for interpreting the tuberculin skin test with PPD 2TU should be established for clinical diagnosis of tuberculosis.

• Journal of Preventive Medicine and Public Health
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• v.31 no.3 s.62
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• pp.564-578
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• 1998

Most extended care facilities have admitted both the healthy and unhealthy elderly, among which members' average caring demand vary. The Aged Welfare Law, however, currently provides no reasonable basis on the staffing policy for extended care facilities. It just reflects the admitted number of the elderly rather than differences in members' average caring demand among facilities. This study is designed to estimate the need for caring staff on the basis of the correlation between the individual health status measured by various tools including Activities of Daily Living and caring demand by actual service time for each one. The sample included all of the admitted elderly(187 persons) in 4 extended care facilities, two in Seoul and the other two in Kangwon-Do over the survey period October 5 through October 20, 1996. The survey process consisted of 3 stages. (1) The current staffing information was collected through self-completed written questionnaires left for head of official in each facility. (2) Six graduate students at School of Public Health interviewed all residents to collect information on their health status and sociodemographics. The response rate for the interview was relatively high(85%). (3) Information on direct and indirect caring time consumed for each residents came from self-completed written questionnaires given to nurses and helpers in each target facilities. Analysis of the data was made using Pearson's correlation and multiple regression technique through SAS program. Based on this procedure, the following was found. 1. No facility meet the staffing standard in the Aged Welfare Law completely. 2. It is actual service time that is most correlated with ADL(Activities of daily living). 3. When all of the elderly are divided by four groups based on the level of ADL, the mean values of needed caring time in each group are 15, 21, 36 and 88 minutes respectively. 4. There is no significant difference among facilities in distribution of elderly person by group. 5. No facility meets the estimated number of nurses and helpers which reflects health status of the admitted elderly. Therefore, it is required that severity of the admitted elderly be considered in establishing staffing standard for extended care facility.

• Progress in Medical Physics
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• v.21 no.3
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• pp.253-260
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• 2010

Most brachytherapy treatment planning systems employ a dosimetry formalism based on the AAPM TG-43 report which does not appropriately consider tissue heterogeneity. In this study we aimed to set up a simple Monte Carlo-based intracavitary high-dose-rate brachytherapy (IC-HDRB) plan verification platform, focusing particularly on the robustness of the direct Monte Carlo dose calculation using material and density information derived from CT images. CT images of slab phantoms and a uterine cervical cancer patient were used for brachytherapy plans based on the Plato (Nucletron, Netherlands) brachytherapy planning system. Monte Carlo simulations were implemented using the parameters from the Plato system and compared with the EBT film dosimetry and conventional dose computations. EGSnrc based DOSXYZnrc code was used for Monte Carlo simulations. Each $^{192}Ir$ source of the afterloader was approximately modeled as a parallel-piped shape inside the converted CT data set whose voxel size was $2{\times}2{\times}2\;mm^3$. Bracytherapy dose calculations based on the TG-43 showed good agreement with the Monte Carlo results in a homogeneous media whose density was close to water, but there were significant errors in high-density materials. For a patient case, A and B point dose differences were less than 3%, while the mean dose discrepancy was as much as 5%. Conventional dose computation methods might underdose the targets by not accounting for the effects of high-density materials. The proposed platform was shown to be feasible and to have good dose calculation accuracy. One should be careful when confirming the plan using a conventional brachytherapy dose computation method, and moreover, an independent dose verification system as developed in this study might be helpful.

• Journal of the Korean Institute of Landscape Architecture
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• v.46 no.5
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• pp.82-92
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• 2018

The purpose of this study is to develop a model for the density management of planting sites and an additional model for new planting sites. In the Dongtan New Town of Hwaseong, there are buffer green spaces, with widths between 8m and 15m, between roads and apartment complexes. A total 38 survey plots were set to examine the planting patterns and the density of landscape trees. The Crown Overlapping Index (COI) was developed to assess the level of overcrowding as far as tree growth and development effectively. Pinus strobus recorded the most serious level of overcrowding growth and development. Its average density and average COI were very high at $0.3trees/m^2$ and 35.6%, respectively. There were many areas in which its COI was above 45%. The criteria for density management were set by standardizing the COI into three levels, which were above 45% (Type A), 30~45% (Type B), and under 30% (Type C). A model was proposed to manage poorly growing trees and to develop a model to select and manage trees of similar specification based on the planting patterns. The trees of density management areas were reviewed in terms of tree types and the ease of transplanting to establish an application system for the management plans according to the possibility of transplanting, thinning, and pruning. In new buffer green spaces, the planting density of Pinus strobus was lowered to $0.20{\sim}0.25trees/m^2$, with that of shrubs being reduced to $1.5{\sim}2.0trees/m^2$, leading to a planting design model to cover the lower parts in at least 30~40%.

• Investigative Magnetic Resonance Imaging
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• v.10 no.2
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• pp.98-107
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• 2006

Magnetization Transfer (MT) imaging generates contrast dependent on the phenomenon of magnetization exchange between free water proton and restricted proton in macromolecules. In biological materials in knee, MT or cross-relaxation is commonly modeled using two spin pools identified by their different T2 relaxation times. Two models for cross-relaxation emphasize the role of proton chemical exchange between protons of water and exchangeable protons on macromolecules, as well as through dipole-dipole interaction between the water and macromolecule protons. The most essential tool in medical image manipulation is the ability to adjust the contrast and intensity. Thus, it is desirable to adjust the contrast and intensity of an image interactively in the real time. The proton density (PD) and T2-weighted SE MR images allow the depiction of knee structures and can demonstrate defects and gross morphologic changes. The PD- and T2-weighted images also show the cartilage internal pathology due to the more intermediate signal of the knee joint in these sequences. Suppression of fat extends the dynamic range of tissue contrast, removes chemical shift artifacts, and decreases motion-related ghost artifacts. Like fat saturation, phase sensitive methods are also based on the difference in precession frequencies of water and fat. In this study, phase sensitive methods look at the phase difference that is accumulated in time as a result of Larmor frequency differences rather than using this difference directly. Although how MT work was given with clinical evidence that leads to quantitative model for MT in tissues, the mathematical formalism used to describe the MT effect applies to explaining to evaluate knee disorder, such as anterior cruciate ligament (ACL) tear and meniscal tear. Calculation of the effect of the effect of the MT saturation is given in the magnetization transfer ratio (MTR) which is a quantitative measure of the relative decrease in signal intensity due to the MT pulse.