• Journal of Korean Neurosurgical Society
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• 제49권1호
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• pp.37-42
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• 2011

Objective: The author measured levels of fluoroscopic radiation exposure to the surgeon's body based on the different beam directions during kyphoplasty. Methods: This is an observational study. A series of 84 patients (96 vertebral bodies) were treated with kyphoplasty over one year. The patients were divided into four groups based on the horizontal and vertical directions of the X-Ray beams. We measured radiation exposure with the seven dosimetry badges which were worn by the surgeon in each group (total of 28 badges). Twenty-four procedures were measured in each group. Cumulative dose and dose rates were compared between groups. Results: Fluoroscopic radiation is received by the operator in real-time for approximately 50% (half) of the operation time. Thyroid protectors and lead aprons can block radiation almost completely. The largest dose was received in the chest irrespective of beam directions. The lowest level of radiation were received when X-ray tube was away from the surgeon and beneath the bed (dose rate of head, neck, chest, abdomen and knee: 0.2986, 0.2828, 0.9711, 0.8977, 0.8168 mSv, respectively). The radiation differences between each group were approximately 2.7-10 folds. Conclusion: When fluoroscopic guided-KP is performed, the X-Ray tube should be positioned on the opposite side of the operator and below the table, otherwise the received radiation to the surgeon's body would be 2.7-10 times higher than such condition.

• 대한의용생체공학회:의공학회지
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• 제38권5호
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• pp.256-263
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• 2017

By using the buildup characteristics of the radiophotoluminescence glass dosimeter(RPLGD), it is aimed to help the measurement of the accurate dose by measuring the radiation dose according to the time of the glass element. Five glass elements were arranged on the table and the source to image receptor distance(SID) was set to 100 cm for the build-up radiation dose measurement of the fluorescent glass dosimeter glass element(GD-352M). Radiation doses and saturation rates were measured over time according to irradiation time, with the tube voltage (30, 60, 90 kVp) and tube current (50, 100 mAs) Repeatability test was repeated ten times to measure the coefficient of variation. The radiation dose increased from 0.182 mGy to 12.902 mGy and the saturation rate increased from 58.3% with increasing exposure condition and time. The coefficient of variation of the glass elements of the fluorescent glass dosimeter was ranged from 0.2 to 0.77 according to the X - ray exposure conditions. X - ray exposure showed that the radiation dose and saturation rate were increased with buildup characteristics, and degeneration of glass elements was not observed. The reproducibility of the variation coefficient of the radiation generator was included within the error range and the reproducibility of the radiation dose was excellent.

• 한국산업보건학회지
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• 제7권2호
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• pp.171-180
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• 1997

The objectives of this study were both 10 discuss the sampling method for airborne metalworking fluids(MWF)' mist and 10 suggest measures to minimize worker's exposure to carcinogen contained in metalworking fluids. In order to measure airborne MWF mist, it seems to be appropriate to use NIOSH Method #0500(filler weight) rather than NIOSH Method # 5026(analysis by FTIR). Because MWF mist on PVC filter evaporated and migrated during sampling, worker's exposure to MWF could be underestimated. So, when evaluating worker's exposure to MWF mist, other environmental conditions also must be considered. Enclosure and local exhaust ventilation system seems to he the most effective measure and must be constructed with process facility. In order to control worker exposure to carcinogens contained in MWF, distillation type and condition for crude oil, PAH concentration in MWF, and viscosity index of MWF must legally be described.

• 한국산업보건학회지
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• 제19권3호
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• pp.195-201
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• 2009

To identify relationship between the airborne concentrations of formaldehyde and the causal factors in the endoscope unit of hospitals, a total of 48 workers selected from 4 hospitals (3 university hospitals and 1 national hospital) were investigated. Airborne formaldehyde samples were collected using passive samplers and subsequently analyzed by HPLC according to the OSHA method 1007. The geometric mean(GM) of airborne formaldehyde concentrations was 0.056 ppm (range: 0.003~0.923 ppm). The rates of exceeding exposure limits of OSHA PEL-TWA and NIOSH REL-TWA were 4.2 % and 83.3%, respectively. The STEL GM concentration was 1.428 ppm(range: 0.103~14.773 ppm). Ventilation condition (p=0.001) and temperature (p=0.017) were statistically significant causal factors for the airborne exposure concentration of formaldehyde in the endoscope unit of hospitals. In conclusion, the workers in the endoscope unit of hospitals were highly exposed to formaldehyde, and adequate controls such as appropriate management of ventilation and temperature are recommended to reduce over exposure to formaldehyde.

• Composites Research
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• 제27권6호
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• pp.236-241
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• 2014

본 연구에서는 공항 포장용 유지보수 재료로 사용되는 폴리머 콘크리트의 자외선 노출에 대한 기계적 물성 변화를 확인하기 위해 자외선 노출 전/후 시편의 압축강도 및 연성인자의 변화를 평가하였다. 현재 공항 포장용으로 사용되는 폴리머 콘크리트의 비율과 선행연구를 통해 얻은 최적 배합비율을 참고하여 시편을 제작하였다. 자외선 발생 램프의 출력을 고려하여 자연상태에서 노출되는 등가시간을 계산한 후 최대 3년에 해당하는 시간만큼의 등가시간 동안 시편을 노출시켰다. 실험결과, 자외선 노출 자체는 재료물성에 거의 영향을 주지 않았으며, 자외선 노출에 따른 온도상승에 의한 재료물성 변화가 주로 관찰되었다. 자외선에 의해 발생된 열에 노출된 후 모든 시편에서 인성은 감소하고, 압축강도는 증가하는 경향을 나타내었다.

• 한국가축번식학회지
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• 제14권2호
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• pp.133-140
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• 1990

This study was conducted to develop a simple and efficient technique for fusing 2-cell mouse embryos to obtain tertraploid embryos. Various concentration of PEG and exposure times were compared in order to determine the best condition for fusion and subsequent of fused embryos. The results obtained were follows ; 1. The incidence of fusion induction treated with 40% PEG(70.8%) and 45%(62.7%) for 60 sec. exposure were higher than those of 40% and 45% PEG for 30 sec., 90 sec., or 120 sec. exposure group. Also, the highest incidence of fusion induction(76.9%) was achieved with 120 sec. exposure at 50% PEG concentration. 2. Fused embryos after PEG treatment were cleavaged 2-to 4-cell, 8-cell, morula and blastocyst at 20-24 hr., 30-34., 44-52 hr., respectively, and were not different from those obtained fleshly. 3. The high proportions of the embryos developed to blastocysts after blastomere fusion with 40% PEG for 60 sec., 45% PEG for 60 sec. and 50% for 120 sec. were 66.7%(42/63), 69.0%(29/42) and 32.0%(16/50), respectively, this trend indicated that the fusion rate was similar to the incidence of fused embryos forming blastocysts. 4. The cell number of blastocyst developed from fused embryos(18.7 2.6) was samller than that of untreated embryos(48.9 1.69)

• 대한방사선기술학회지:방사선기술과학
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• 제20권1호
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• pp.71-75
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• 1997

This study was Investigation that we will become aware of the scattering dose of duty station and TLD value of the radiation exposure by the radiation technologists based on the university hospital located in Kwang ju. The results are followings ; 1. The air of scattering dose in chest, when the number of objects are large, is 2.0 mR in P-A and 4.6 mR in Lat. at the back of X-ray tube 2. Radiologists, radiation exposure in duty station Is 0.22 mSv to 1.96 mSv in general examination, 0.22 mSv to 1.12 mSv in contrast and special examination, 0.26 mSv to 30.96 mSv in angiography, and 0.22 mSv to 0.40 mSv in C.T 3. The value of workig condition reveals 85.5% in general examination, 6% in contrast and special examination, and 5.8% in C.T. When the annual exposure is over 20 mSv, it must be measured again according to ICRP public 60.

• Journal of Pharmaceutical Investigation
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• 제36권4호
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• pp.231-237
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• 2006

Hypoxia in solid tumors is known to contribute to intrinsic chemoresistance. Histocultures are in vitro 3 dimensional cultures of tumor tissues and maintain the characteristic microenvironment of human solid tumors in vivo including hypoxia and multicellular structure. In this study, we evaluated the pharmacodynamics of tirapazamine(TPZ), a hypoxia-selective cytotoxin, in human non small cell lung cancer(NSCLC) cells grown as monolayers and histocultures. Antiproliferative activity of TPZ was determined after various conditions of drug exposure, and cell cycle arrest and apoptosis were also measured using flow cytometry. In monolayers, hypoxia selectivity measured by hypoxic/normoxic cytotoxicity ratio was increased with longer exposure. Lower cytotoxicity of TPZ was observed in histocultures compared to monolayers, however, a similar level of cytotoxicity was obtained with longer exposure of 96 hr. TPZ induced $G_2/M$ arrest and apoptosis in both culture conditions, which were greatly enhanced under hypoxic condition. Our data clearly showed the different pharmacodynamics of TPZ in monolayers and histocultures. Antiproliferative activity of TPZ against human solid tumors can be improved with longer drug exposure by exploiting drug delivery systems or by combining angiogenesis inhibitors to maintain drug concentration in tumor tissues.

• 한국컴퓨터정보학회논문지
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• 제22권6호
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• pp.149-156
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• 2017

In this paper, we propose to enhance a Physical working conditions to decrease absence from work. we demonstrated the correlation of worker's absence with various environmental factors in workplace by surveying 6,962 workers. As result, first, concerning exposure to physical work factors, most of them complained of vibration, and concerning exposure to improper working posture, most of them complained of repetitive arm and hand motions. Second, the absence experience had correlations with age, monthly income, smoking, number of employees, long term working, and shift work, and of the physical factors, hand vibration, noise, high temperature, low temperature and improper working posture had correlations with physical pain posture, movement of people and carrying heavy materials. Third, experience of exposure to hand vibration, noise and low temperature of the physical factors had impact on absence, and of the improper working posture, physical pain posture and carrying heavy stuff had impacts on absence. Through this study, it was found that of the work factors of Korean workers, physical factors and improper working posture had impacts on absence. The results of this study confirmed that physical factors and inappropriate working posture among work factors influenced the absenteeism. Therefore, it is required to improve the work environment regarding physical risk factors and prepare a systematic management plan.

• Fisheries and Aquatic Sciences
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• 제22권5호
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• pp.9.1-9.7
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• 2019

The study investigated the changes in growth performance, hematological parameters, plasma components, and stress indicators of juvenile starry flounder, Platichthys stellatus, depending on varying exposure to hexavalent chromium. P. stellatus was exposed to waterborne chromium at 0, 50, 100, 200, and 400 ppb for 4 weeks. The result showed that Cr exposure resulted in decreased daily length gain (DLG), daily weight gain (DWG), condition factor (CF), and hepatosomatic index (HIS) in P. stellatus. In terms of hematological parameters, red blood cell (RBC) count, hematocrit (Ht), and hemoglobin (Hb) significantly decreased at 400 ppb after 2 weeks. In terms of plasma components, inorganic analysis was unchanged and cholesterol, an organic component, considerably increased at 400 ppb after 4 weeks. Plasma enzyme components including glutamic oxalate transaminase (GOT) and glutamic pyruvate transaminase (GPT) were significantly increased. Stress indicators such as cortisol and glucose were notably increased over 100 ppb after 4 weeks with increasing chromium concentration. The results indicate that exposure to waterborne Cr induced toxic effects on growth, hematological parameters, plasma components, and stress indicators.