• 한국패류학회지
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• 제29권1호
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• pp.23-32
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• 2013

The purpose of this study is to evaluate the effects of oil dispersant and ultraviolet (UV) radiation on the toxicity of crude oil. The toxicity of water-accommodated fraction (WAF) and chemically enhanced water-accommodated fraction (CEWAF) of Hebei Spirit crude oil was investigated in the embryo of the Manila clam, Ruditapes philippinarum with- and without ultraviolet radiation. The WAF and CEWAF with- and without UV radiation affected significantly the embryonic development of R. philippinarum. The EC50s of WAF without UV, WAF with UV, CEWAF without UV, and CEWAF with UV were 2.82, 0.79, 1.60, and 0.45 g/L, respectively. CEWAF was 1.6 times more toxic than WAF. UV radiation increased crude oil toxicity to 3.6 times for both WAF and CEWAF. The oil dispersant and UV radiation did not affect the acute toxicity to the embryo but retarded the period of embryonic development up to 26%. R. philippinarum proved to be a sensitive species to reflect the toxic effects of oil spill combined with oil dispersant and UV radiation. It is suggested that the chemical analyses on the WAF and CEWAF is important for the identification and quantitative explanation of the phototoxic compounds in crude oil.

• 대한방사선기술학회지:방사선기술과학
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• 제11권2호
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• pp.3-15
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• 1988

When X-rays were projected into a patient, there occured the phenomena such as penetration, absorption and scattering etc. The penetrating rays were recorded on films as X-ray image used for diagnosis but scattered rays caused the radiation hazard both to the patient, specialist and technicians. The soft tissue includes many organs which are sensitive to the radiation and in may occupy $40{\sim}50%$ of body weight. Therefore X-rays should be carefully projected to the patient and it is strongly recommended to analyse the distribution of X-rays, when ever the patient is exposed to X-rays. In this study, the distribution of X-ray according to the thickness, the radiation field and the tube voltages (kVp) in soft tissue, the following results were obtained: 1. Total transmitted rays which kept the step with X-ray tube voltage (kVp) increased in proportion to the increasing of X-ray tube voltage. 2. The scattered ray rate in the total transmitted ray was not significantly found with X-ray tube voltage. 3. The affecting factors of the scattered ray rate in total transmitted ray were shown through the radiation field and the thickness. 4. The dose of scattered ray by the angle was observed more in direction of primary ray ($0^{\circ}$) and back scattering ($160^{\circ}$) than in direction of $90^{\circ}$. 5. The more the distance from phantom to the patient should be less distribution of scattered ray.

• 방사선산업학회지
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• 제3권1호
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• pp.25-29
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• 2009

Microarrays can be used to screen thousands of binding events in a parallel and high throughput fashion and are of major importance in disease diagnosis and drug discovery. The use of radioisotope is conventionally regarded as one of the most sensitive detection methods. Atherosclerosis is a common disorder affecting arterial blood vessels. It happens when fat, cholesterol, and other substances made in the arterial blood vessels form a hard substances called plaque. Lipoprotein-associated phospholipase $A_2$ ($Lp-PLA_2$), a phospholipase $A_2$ enzyme, is used as a marker for cardiac disease. The detection of $Lp-PLA_2$ was accomplished by using radioactive [$^3H-acetyl$] PAF as a substrate and a feasibility study on RI biochip application to detection of $Lp-PLA_2$, a risk factors of atherosclerosis was performed. Inhibitive activity of a native plant extract was also determined by using the RI biochip. It was found to be applicable to a high-throughput screening of inhibitors for developing atherosclerosis therapeutic agents.

• Radiation Oncology Journal
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• 제11권2호
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• pp.205-217
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• 1993

In order to evalute the effects of radiation on mammalian neuronal system, we have examined the effect of gamma-ray radiation on the monoamine oxidase (MAO) activity in monoaminergic neurons. Following the whole body irradiation, MAO activity in the rat brain was measured as well as in the liver for the comparative studies between the neuronal and nonneuronal system. The effects of some radiation protectors and sensitizers were also examined in addition to the $O_2$ effect. The results can be summarized as follows. 1) The MAO activity of rat brain was minimally affected by the radiation dose up to 1,700 cGy Radiation dose above 2,500 cGy inhibited the brain MAO activity by no less than $l0\%.$ MAO-A form was found to be particularly sensitive to radiation. The liver MAO was somewhat inhibited (by about $5\%$) but hardly dependent on the dose of radiation. 2) The inhibitory effect on the brain was initiated immediately by the radiation dose of 2,500 cGy. On the contrary, for the liver, the inhibitory effect became apparent only 2 days after irradiation. 3) Two days after a dose of 2,500 cGy, Vmax and Km of the brain mitochondrial MAO decreased. For liver, Vmax decreased while Km increased, which indicates the kinetic patterns for the neuronal and nonneruronal systems are not affected similarly by radiation. 4) The effect of several known radiation protectors and sensitizers on MAO activity was tested ut no definite results were obtained. The level of -SH group increased in some degree upon radiation but not by the compounds. 5) MAO activity was not affected by $O_2$ concentration, while an elevated level of lipid peroxidase was found under the same condition. The results described here indicate that characteristics of MAO, one of the most important central nervous system enzymes, are liable to radiation, which is partially differentiated from the liver MAO. Also indicated are that the -SH groups are hardly related to the effect of radiation but the production of the lipid peroxide seems to be somewhat correlated to the effect of radiation.

• The Korean Journal of Physiology
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• 제19권1호
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• pp.15-23
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• 1985

$(Na^++K^+)-ATPase$은 ${\alpha}$ 와 ${\beta}$의 두 subunits로 구성되어 있으며, 분자량이 약 300,000 daltons 정도되는 것으로 보아 ${\alpha}_2{\beta}_2$의 형태로 존재할 것으로 알려져 왔다 한편, 사람 적혈구막에 있는 $Na^+,\;K^+\;Pump$는 glycolytic enzymes과 complex를 이루고 있으리라는 보고도 있다. 우리는 이 실험에서 in situ상태의 사람 적혈구막$(Na^++K^+)-ATPase$의 분자량을 측정하기 위하여, 소위 말하는 ‘Target theory’를 radiation에 의한 ouabain sensitive한 $\Na^+$이동과, intact한 cells과 ghosts에서의 ATP가수분해능력의 inactivation data에 적용하였다. Intact한 cells은 cryoprotective agent의 존재하에서, ghosts는 직접적으로 액화질소의 용기속에 담고 온도를 $-45^{\circ}C$에서 $-50^{\circ}C$로 유지시키면서 1.5 MeV의 electron beam으로 조사한 후에 Pump의 기능내지 효소의 활성도를 측정하여 radiation에 따르는 inactivation의 정도를 측정하였다. 이득 활성도는 radiation의 양에 따라 simple exponential function으로 inactivation되었으며, 이로부터 radiation sensitive volume(target size)를 계산하였다. Target size는 intact한 cells을 사용하였을 경 우$(Na^++K^+)-ATPase$나 $Na^+,\;K^+\;Pump$ 모두 600,000 daltons으로 계산되었으며, 이 값은 만약 cells을 strophanthidin으로 먼저 처치하고 측정하면 약 325,000 daltons으로 감소하였다. Ghosts를 사용했을 경우에도$(Na^++K^+)-ATPase$의 target size는 역시 약 325,000 daltons이었다. 이상의 결과로 미루어 보아 intact한 cells에서는 $(Na^++K^+)-ATPase/Na^+,\;K^+\;Pump$가 $(\alpha\beta)_2$의 dimer 상태로 존재하거나 혹은 $(\alpha\beta)_2$의 monomer에 glycolytic enzymes과 같은 다른 enzymes이 붙어 functional한 구조를 이루고 있는 것이 아닌가 사료된다. 또한 실헐성적은 이러한 dimeric association 혹은 heterocomplex association은 ghost를 만드는 과정에서나 strophanthidin의 처치로 부서질 수 있음을 암시하고 있다.

• 대한방사선기술학회지:방사선기술과학
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• 제43권5호
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• pp.343-351
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• 2020

This study analyzed dose reduction and quality of images through dose reduction tools and shielding board to protect sensitive eye lens in radiation during orbit CT examinations for clinical data use. During CT scans of the phantom, surface dose (CT scanner dosimetry phantom, ion chamber-3 times) and quality of image (radiosurgery head phantom, visual assessment-2 times, HU standard deviation) were evaluated using X-care which is dose reduction tools and bismuth shielding board. The results of experiments of eight conditions showed a relatively reduced dose in all other conditions compared to when no conditions were set. In particular, the area corresponding to the ophthalmic part reduced the surface dose by up to 45.7 %. The visual evaluation of images by specialists and the quality evaluation of images analyzed by HU standard deviation were clinically closest to the use of X-care and shielding board (1 cm in height). Therefore, it is believed that the use of shielding board in a suitable location with dose reduction tools while investigating the optimal radiation dose will reduce the exposure dose of sensitive lens at radiation while maintaining the quality of the images with high diagnostic value.

• Nuclear Engineering and Technology
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• 제56권1호
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• pp.56-63
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• 2024

In high radiation fields, gamma cameras suffer from pulse pile-up, resulting in poor energy resolution, count losses, and image distortion. To overcome this problem, various methods have been introduced to reduce the size of the aperture or pixel, reject the pile-up events, and correct the pile-up events, but these technologies have limitations in terms of mechanical design and real-time processing. The purpose of this study is to develop a real-time gamma camera to evaluate the radioactive contamination in high radiation fields. The gamma camera is composed of a pinhole collimator, NaI(Tl) scintillator, position sensitive photomultiplier (PSPMT), signal processing board, and data acquisition (DAQ). The pulse pile-up is corrected in real-time with a field programmable gate array (FPGA) using the start time correction (STC) method. The STC method corrects the amplitude of the pile-up event by correcting the time at the start point of the pile-up event. The performance of the gamma camera was evaluated using a high dose rate ¹³⁷Cs source. For pulse pile-up ratios (PPRs) of 0.45 and 0.30, the energy resolution improved by 61.5 and 20.3%, respectively. In addition, the image artifacts in the ¹³⁷Cs radioisotope image due to pile-up were reduced.

• 폴리머
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• 제36권3호
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• pp.344-350
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• 2012

전자선 조사 방법을 이용하여 편광필름용 아크릴계 고분자를 가교화시킨 후 이의 점착 특성을 평가하였다. 아크릴 공중합체는 $n$-butylacrylate(BA), 2-hydroxyethyl methacrylate(HEMA), acrylic acid(AA)를 기본 단량체로 하여 다양한 조성으로 중합하였다. 아크릴 공중합체를 25 ${\mu}m$ 두께로 PET 이형필름에 코팅한 후 편광필름에 합지하고 그 위에 전자선을 조사하여 아크릴 공중합체의 가교화 반응을 진행하였다. 모든 아크릴 공중합체는 조사선량 50 kGy에서 93% 이상의 높은 젤분율을 보였으며, 아크릴 공중합체에 도입된 HEMA 단위가 많을수록 높은 가교밀도를 보였다. BA/HEMA/AA(89.5/10/0.5 w/w/w)의 단량체 공급비로 중합된 아크릴 공중합체에 50 kGy로 전자선을 조사하여 얻어진 아크릴 점착제가 가장 우수한 박리력, 내크리프성, 내구신뢰성, 내열빛샘 특성을 보였다. 전자선 조사를 이용한 편광필름용 아크릴계 점착제의 제조 방법을 적용하면 액정 표시장치용 편광필름의 생산성 및 작업성을 크게 개선할 것으로 기대된다.

• 대한방사선기술학회지:방사선기술과학
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• 제38권1호
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• pp.51-61
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• 2015

모든 방사선 검사는 검사를 결정하고 실행하는 과정에서 정당성이 확보되어야하고 피폭선량과 영상의 화질에 대한 최적화가 이루어져야 할 뿐만 아니라 ALARA의 원칙에 따라 최소의 방사선을 사용하여 최적의 임상 정보를 얻을 수 있어야 한다. CT 검사는 방사선 검사 중에서 많은 피폭을 환자에게 조사하는 검사이다. 특히 방사선 민감도가 높은 소아 환자의 CT 검사 있어서는 특별한 주의가 필요하다. 임상에서 CT선량에 대한 정확한 이해와 정보는 환자에게 불필요한 방사선 피폭을 줄이고 안전한 검사를 제공하기 위해 절대적으로 필요하다. 이에 본 연구에서는 여러 선행 연구의 고찰을 통하여 CT의 피폭선량에 대한 개념을 확인하고 CT장치의 선량 저감화를 위한 각 파라미터의 이해와 American Association of Physicists in Medicine (AAPM)report 204에서 소개하고 있는 환자의 사이즈에 따른 피폭선량의 보정방법인 Size-Specific Dose Estimates(SSDE)와 XR 25의 개념을 이해하고자 한다.

• 한국농공학회논문집
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• 제60권3호
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• pp.15-25
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• 2018

Estimating the reference evapotranspiration is an important factor to consider in irrigation system design and agricultural water use. However, there is a limitation in using the FAO Penman-Monteith (FAO P-M) equation, which requires various meteorological data. The purpose of this study is to compare three reference evapotranspiration (ETo) equations in the case of meteorological data missing for 11 study weather stations. Firstly, the FAO P-M equation is used for reference potential evapotranspiration estimation with the actual solar radiation data $R_n$ and the actual vapor pressure $e_a$. Then, in the case of $R_n$, and $e_a$ are missed, the reference evapotranspirations applying FAO P-M, Priestley-Taylor (P-T), Hargreaves (HG) equation were calculated using other meteorological factors. Secondly, MAE, RMSE, $R^2$ were calculated to compare ETo relationship from the ETo equations. From the results, ETo with Hargreaves equation in coastal areas and the Priestley-Taylor equation in the inland areas showed relatively high correlation with FAO P-M when $e_a$ data is missed. In the case of $R_n$ data is missed or two weather data, $e_a$, and $R_n$ data are all missed, $R^2$ value in Priestley-Taylor equation was highest in coastal areas, and $R^2$ values in Hargreaves equation were the high values for 7 inland areas. The results of sensitivity analysis showed that net radiation was the most sensitive for P-T and HG equation, and for FAO P-M, the most sensitive factor was net radiation and relative humidity, air temperature and wind speed were follows. Therefore, in considering of the accessibility to the coast, the types of the missing wether data, and the correlation and the magnitude of error, the reference evapotranspiration equations would be selected in sense of different conditions.