• Resources Recycling
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• v.9 no.4
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• pp.16-27
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• 2000

In order to produce raw material powder of advanced magnetic material by spray roasting process, newly modified spray roasting system was developed in this work. In this spray roasting system, raw material solution was effectively atomized and sprayed into the reaction furnace. Also, uniform temperature distribution inside reaction furnace made thermal decomposition process fully completed, and produced powder was effectively collected in cyclone and bag filter. This system equipped with apparatus which can purify hazard produced gas. In this study complex acid solution was prepared by dissolution of mill scale and ferro-Mn into the acid solution, and the pH of this complex acid solution was controlled about to 4. It was conformed that mill scale and ferro-Mn containing a lot of impurities such as $SiO_2$, P and Al could be used as raw material by reducing the impurities content of complex acid solution below 20 ppm. Complex oxide powder of Fe-Mn system was produced by spraying purified complex acid solution into the spray roaster through nozzle, and the variations of produced powder characters were studied by changing he reaction conditions such as reaction temperature, the injection velocity of solution and air, nozzle tip size and concentration of solution. The morphology of produced powder had spherical shape under the most experimental conditions, and concentration of solution. The morphology of produced powder has spherical shape under the most experimental conditions, and the composition and the particle size distribution were almost uniform, which tells the excellence of this spray roasting system. The grain size of most produced powder was below 100 nm. From the above results, it will be possible to produce ultra fine oxide powder from the chloride of Fe, Mn, Ni, Cu and rare earth by using this spray roasting system, and also to produce ultra fine pure metal powder by changing reaction atmosphere.

• Journal of The Korean Ophthalmological Society
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• v.59 no.12
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• pp.1166-1172
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• 2018

Purpose: To investigate the efficacy, and identify predictors of success of selective laser trabeculoplasty (SLT) in open-angle glaucoma (OAG) patients after adjusting for intraocular pressure (IOP) changes in the untreated fellow eye. Methods: This retrospective chart review included 52 eyes of 52 OAG patients who underwent SLT in one eye and were followed-up for at least 1 year after the procedure. The IOP was measured before the treatment, at 1, 2, and 3 months posttreatment, and every 3 months thereafter. To account for the possible influence of IOP fluctuations on laser outcomes, post-laser IOP values of the treated eye of each patient were also analyzed, after adjusting for IOP changes in the untreated fellow eye. Success was defined as an IOP decrease ${\geq}20%$ of the pretreatment IOP. The success rate was determined based on Kaplan-Meier survival analysis and factors predictive of success were analyzed using the Cox proportional hazard model. Results: The mean pretreatment IOP was $23.17{\pm}6.96mmHg$. The mean IOP reduction was $5.59{\pm}4.78mmHg$ (29.7%) and the success rate was 65.4% at 1 year. The adjusted mean IOP reduction was $4.70{\pm}4.67mmHg$ (23.9%) and the adjusted success rate was 53.9%. Pretreatment IOP was associated with SLT success; the higher the pretreatment IOP, the greater the post-laser IOP reduction (p = 0.025). Age and mean deviation index did not show a significant association with SLT success (p = 0.066 and p = 0.464, respectively). Conclusions: SLT is a safe and effective alternative method of IOP reduction in OAG patients. Herein, pretreatment IOP was the only factor significantly associated with SLT success. IOP fluctuations of the untreated eye should be considered for a better understanding of the impact of treatment.

• Journal of the Society of Disaster Information
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• v.18 no.1
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• pp.182-193
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• 2022

Purpose: By measuring and evaluating the risk of biodiesel through non-volatile residue (NVR) and flash point and explosion limit measurement at a specific temperature according to ASTM test standards, the risk of chemical fire causative substances is identified and a universal evaluation method By derivation and securing the risk-related data of the material, it can be used for the identification and analysis of the cause of the fire, and it can be applied to the risk assessment of other chemical substances Method: In order to measure the risk of biodiesel, it was measured using the non-volatile residue(NVR) measurement method, which measures how much flammable liquid is generated at a specific temperature. Heating was tested by applying KS M 5000: 2009 Test Method 4111. In addition, the flash point was measured using the method specified in ASTM E659-782005, and the energy supply method was measured using the constant temperature method. In addition, the explosion limit measurement was conducted in accordance with ASTM E 681-04 「Standard test method for concentration limits of flammability of chemicals(Vapors and gases)」 test standard. Result: As a result of checking the amount of combustible liquid by the non-volatile residue (NVR)measurement method, the non-volatile residue(NVR) of general diesel when left at 105±2℃ for 3 hours was about 30% (70% of volatile matter) and about 4% of biodiesel. In addition, similar results were obtained for the non-volatile residue(NVR)heating temperature of 150±2℃, 3 hours and 200±2℃ for 1 hour, and white smoke was generated at 200℃ or higher. In addition, similar values were obtained as a result of experimentally checking the explosion (combustion) limits of general diesel, general diesel containing 20% biodiesel, and 100% biodiesel. Therefore, it was confirmed that the flammability risk did not significantly affect the explosion risk. Conclusion: The results of this study suggested the risk judgment criteria for mixtures through experimental research on flammable mixtures for the purpose of securing the effectiveness, reliability, and reproducibility of the details of the criteria for determining dangerous substances in the existing Dangerous Materials Safety Management Act. It will be possible to provide reference data for the judgment criteria for flammable liquids that are regulated in the field. In addition, if the know-how for each test method is accumulated through this study, it is expected that it will be used as basic data in the research on risk assessment of dangerous substances and as a basis for research on the determination of dangerous substances.

• Korean Journal of Radiology
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• v.21 no.7
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• pp.880-890
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• 2020

Objective: Patients with chronic obstructive pulmonary disease (COPD) are known to be at risk of osteoporosis. The purpose of this study was to evaluate the association between thoracic vertebral bone density measured on chest CT (D_Thorax) and clinical variables, including survival, in patients with COPD. Materials and Methods: A total of 322 patients with COPD were selected from the Korean Obstructive Lung Disease (KOLD) cohort. D_Thorax was measured by averaging the CT values of three consecutive vertebral bodies at the level of the left main coronary artery with a round region of interest as large as possible within the anterior column of each vertebral body using an in-house software. Associations between D_Thorax and clinical variables, including survival, pulmonary function test (PFT) results, and CT densitometry, were evaluated. Results: The median follow-up time was 7.3 years (range: 0.1-12.4 years). Fifty-six patients (17.4%) died. D_Thorax differed significantly between the different Global Initiative for Chronic Obstructive Lung Disease stages. D_Thorax correlated positively with body mass index (BMI), some PFT results, and the six-minute walk distance, and correlated negatively with the emphysema index (EI) (all p < 0.05). In the univariate Cox analysis, older age (hazard ratio [HR], 3.617; 95% confidence interval [CI], 2.119-6.173, p < 0.001), lower BMI (HR, 3.589; 95% CI, 2.122-6.071, p < 0.001), lower forced expiratory volume in one second (FEV₁) (HR, 2.975; 95% CI, 1.682-5.262, p < 0.001), lower diffusing capacity of the lung for carbon monoxide corrected with hemoglobin (DL_CO) (HR, 4.595; 95% CI, 2.665-7.924, p < 0.001), higher EI (HR, 3.722; 95% CI, 2.192-6.319, p < 0.001), presence of vertebral fractures (HR, 2.062; 95% CI, 1.154-3.683, p = 0.015), and lower D_Thorax (HR, 2.773; 95% CI, 1.620-4.746, p < 0.001) were significantly associated with all-cause mortality and lung-related mortality. In the multivariate Cox analysis, lower D_Thorax (HR, 1.957; 95% CI, 1.075-3.563, p = 0.028) along with older age, lower BMI, lower FEV₁, and lower DL_CO were independent predictors of all-cause mortality. Conclusion: The thoracic vertebral bone density measured on chest CT demonstrated significant associations with the patients' mortality and clinical variables of disease severity in the COPD patients included in KOLD cohort.

• Journal of Radiation Protection and Research
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• v.32 no.4
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• pp.140-156
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• 2007

This research was performed to investigate the morphological changes of folliculus ovary according to the radiation dose. The whole body radiation of 200 cGy, 400 cGy, and 600 cGy was given to the each groups of 5 months-aged female mouse. Various staining methods used in this research are: Hematosylin-Eosin method, and immunohistochemistrical methods using BrdU, TUNEL, p53, p21, PCNA and inhibin. The minute structural changes of folliculus ovary were observed through an electron microscope with high magnification. The morphological changes of growing folliculus ovary became distinct as the dose of X-rays increased. Especially, the nuclei of granular cells showed manifest condensation and the changes of the transparent zone were distinct. As a result of histochemical reaction according to Masson's trichrome method and reticular fiber method, the changed granular cells, the deformed basilar membrane of folliculus ovary and the abnormal arrangement of the reticular fiber were observed. In the reaction of BrdU, the granular cells of normal folliculus ovary with positive reaction rapidly decreased according to the increase of the dose of X-rays. In TUNEL study, granular cells showing positive reaction in retarded folliculus ovary were expanded to growing folliculus ovary and primordial folliculus ovary according to the increase of the dose of X-rays. In case of 600 cGy of X-rays, oocyte underwent apoptosis. In p53 immunohistochemistry, p53 manifested to be stronger as the dose of X-rays increased. p53 reactivity was manifested distinctively in all cells comprising folliculus ovary following irradiation of 600 cGy. p21 was manifested in granular cells of folliculus ovary and showed very positive reaction around follicular antrum according to the increase of the dose of X-rays. In PCNA, positive reaction was manifested in growing folliculus ovary, mature folliculus ovary and primordial folliculus ovary, but the extent of the reaction decreased as the dose of the X-rays decreased. The finding that the reaction of granular cells around folliculus ovary was stronger than that near follicular membrane indicates that what was damaged first by X-ray was the cells near folliculus ovary and follicular antrum. The reactivity of $inhibin-{\alpha}$ showed difference according to the growing stage of folliculus ovary: $inhibin-{\alpha}$ showed the most strong reaction in mature folliculus ovary with follicular antrum. There was strong reaction in granular cells around follicular membrane but $inhibin-{\alpha}$ did not occur at all in theca cells comprising follicular membrane. $Inhibin-{\alpha}$ in ovary tissue exposed to 400 cGy of X-rays was manifested more strongly than in ovary tissue exposed to 600 cGy of X-rays, which was related to the phenomenon that granular cells of mature folliculus ovary underwent necrosis or apoptosis increasingly due to X-rays. In an electron microscope with high magnification, nuclei and protoplasm of granular cells in growing folliculus ovary abruptly underwent minute structural changes according to the increase of dose of X-rays. Cell residue, by-product of cell decease, neutrophil and macrophage around follicular antrum were observed. The minute structural changes in granular cells showed typical characteristics of apoptosis: the increase of electronic density due to nuclear condensation, fragmentation of nuclei and atrophy of protoplasm. Necrosis of cells was identified but it was not so remarkable. Macrophage with apoptotic bodies was scattered. Proportional to the radiation dose, we found that the generation of heterogeneous substance of normal ovary texture's follicular fluid, the emergence of dyeing characteristic in the basilar membrane of folicle, the generation of apoptosis, and the transformation of macrophages, etc. From this results, we can infer the possible radiation hazard on the ovary of cervix cancer patient with radiation therapy.

• Radiation Oncology Journal
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• v.18 no.2
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• pp.157-166
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• 2000

Purpose : This investigation was peformed in order to improve the health care of radiation workers, to predict a risk, to minimize the radiation exposure hazard to them and for them to realize radiation exposure danger when they work in radiation area in hospital. Methods and Materials : The documentations checked regularly for personal radiation exposure in four university hospitals in Pusan city in Korea between January 1, 1993 and December 31, 1997 were analyzed. There were 458 persons in this documented but 111 persons who worked less then one year were excluded and only 347 persons were included in this study. Results : The average of yearly radiation exposure of 347 persons was 1.52$\pm$1.35 mSv. Though it was less than 50mSv, the limitaion of radiation in law but 125 (36%) people received higher radiation exposure than non-radiation workers. Radiation workers under 30 year old have received radiation exposure of mean 1.87$\pm$1.01 mSv/year, mean 1.22$\pm$0.69 mSv between 31 and 40 year old and mean 0.97$\pm$0.43 mSv/year over 41year old (p<0.001). Men received mean 1.67$\pm$1.54 mSv/year were higher than women who received mean 1.13$\pm$0.61 mSv/year (p<0.01). Radiation exposure in the department of nuclear modicine department in spite of low energy sources is higher than other departments that use radiations in hospital (p<0.05). And the workers who received mean 3.59$\pm$1.81 msv/year in parts of management of radiation sources and injection of sources to patient receive high radiation exposure in nuclear medicine department (p<0.01). In department of diagnostic radiology high radiation exposure is in barium enema rooms where workers received mean 3.74$\pm$1.74 mSv/year and other parts where they all use fluoroscopy such as angiography room of mean 1.17$\pm$0.35 mSv/year and upper gastrointestinal room of mean 1.74$\pm$1.34 mSv/year represented higher radiation exposure than average radiation exposure in diagnostic radiology (p<0.01). Doctors and radiation technologists received higher radiation exposure of each mean 1.75$\pm$1.17 mSv/year and mean 1.50$\pm$1.39 mSv/year than other people who work in radiation area in hospital (p<0.05). Especially young doctors and technologists have the high opportunity to receive higher radiation exposure. Conclusions : The training and education of radiation workers for radiation exposure risks are important and it is necessary to rotate worker in short period in high risk area. The hospital management has to concern health of radiation workers more and to put an effort to reduce radiation exposure as low as possible in radiation areas in hospital.