• Journal of Radiation Industry
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• v.6 no.1
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• pp.55-59
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• 2012

Polyacrylonitrile (PAN)-based carbon fibers have been widely used due to their unique chemical, electrical, and mechanical properties. Electron beam irradiation has been extensively employed as means of altering properties of polymeric materials. Electron beam irradiation can induce chemical reactions in materials without any catalyst. Electron beam irradiation may be useful in accelerating the thermal compression stabilization of PAN nanofibers. To investigate the irradiation effect on PAN fibers, PAN nanofibers were irradiated by electron beam at 1,000~5,000 kGy. Irradiated and non-irradiated PAN nanofibers were heated at 180 and $220^{\circ}C$ without applying pressure for 15 min. Then 1 metric ton has been applied for 5 min. SEM images have been found that the fiber kept its morphological behavior after the hot pressing up to electron beam irradiated 1,000 kGy. DSC thermograms showed that the peak temperatures of the exothermic reactions were found to decrease with increasing electron beam irradiation doses and temperature. FT-IR spectra have been found to decrease $C{\equiv}N$ stretch band with increasing the electron beam irradiation dose. These results indicate that the modification of PAN via reactions such as cyclization is significantly enhanced by electron beam irradiation and thermal compression technique.

• BMB Reports
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• v.36 no.1
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• pp.60-65
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• 2003

Cancer is frequently considered to be a disease of the cell cycle. As such, it is not surprising that the deregulation of the cell cycle is one of the most frequent alterations during tumor development. Cell cycle progression is a highly-ordered and tightly-regulated process that involves multiple checkpoints that assess extracellular growth signals, cell size, and DNA integrity. Cyclin-dependent kinases (CDKs) and their cyclin partners are positive regulators of accelerators that induce cell cycle progression; whereas, cyclin-dependent kinase inhibitors (CKIs) that act as brakes to stop cell cycle progression in response to regulatory signals are important negative regulators. Cancer originates from the abnormal expression of activation of positive regulators and functional suppression of negative regulators. Therefore, understanding the molecular mechanisms of the deregulation of cell cycle progression in cancer can provide important insights into how normal cells become tumorigenic, as well as how cancer treatment strategies can be designed.

• Proceedings of the Korea Society of Environmental Toocicology Conference
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• 2003.05a
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• pp.178-179
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• 2003

The testis is composed of four cell types like supporting cells, steroid-producing cells, connective tissue cells and germ cells. Apoptosis is a common phenomenon during spormatogenesis. Apoptosis of germ cells can also be induced by exposure to radiation. Previous studies have shown that most types of germ cells are rather radiosensitive while somatic cells in testis are much more radio-resistant. The somatic cells in testis are divided to mainly Sertoli and Leydig cells. Though somatic cells are more radio-resistant than germ cells, radiation can induce the impairment of their function. This damaged function of somatic cells may accelerates degeneration of germ cell indirectly. Tn the present study, we have examined the apoptotic effect of mouse testis and irradiation effect of steroidogenesis of Leydig cells after irradiation.

• The Journal of Korean Physical Therapy
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• v.13 no.3
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• pp.637-642
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• 2001

Hershel found out Infrared for the first time, in the Industrial Revolution the Infrared and FlR had been begun to use making products. FIR with low temperature can deeply penetrate on the human body composed things without troublesome. since FIR has effectively operated on the human body at low temperature (35-40$^{\circ}$C). When FIR penetrated on the human body, it would inhibit the abnormal genes and cells expression, and then information of DNA and RNA would be reexpressed for arranging DNA and RNA abnormal state. As FIR's receptors in the body, it colud be presumed that N-glycosyl linkage of purine and deoxyribose, RNA splicing process. and Heat shock protein. To radiate optimized FIR, in this study, we made the FIR radiation compound and instrument for unharming biological things. According to the results, the FIR radiation to E. coli., it did not induce genetic mutations and change the survival rate of E.coli.

• Parasites, Hosts and Diseases
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• v.41 no.1
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• pp.41-45
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• 2003

Effects of gamma irradiation on the worm survival and chromosomal aberration of Clonorchis sinensis were studied. The metacercariae irradiated with various amounts of gamma radiation (ranging from 5 Gy to 50 Gy) were fed to rats, and the effects were compared with those of non-irradiated controls. Recovery rates of adult worms in irradiated groups were reduced gradually as increasing of the irradiation doses. No worm was recovered from rats which were fed with 50 Gy irradiated metacercariae. The chromosome number was 2n = 56 in all worms from all experimental groups. However, the groups irradiated with 20 Gy, 25 Gy or 30 Gy showed variations in the chromosome number, depending on different cells in the same individual. Radiation doses used in this study did not appear to induce chromosome aberrations, however, irradiation with 30 Gy showed slightly reduced chromosome size.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2006.11a
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• pp.455-457
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• 2006

The effects of UV-B irradiation on the growth and photosynthetic activity were investigated in seedlings of sunflower(Helianthus annuus L.). The first leaves irradiated with UV-B were retarded in growth but simultaneously acquired a remarkably decreased chlorophyll fluorescence ratio compared with the non-irradiated leaves. The Fv/Fm ratio decreased by 13 % compared to the control after 2 d, and was kept to be lower than the control level until 5 d. From the results it is suggested that UV-B radiation may induce reduced biomass production and decrease in photosynthetic rate in sunflower plants.

• Journal of the Korean Society of Safety
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• v.19 no.3 s.67
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• pp.26-31
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• 2004

The radiation-induced changes taking place in poly(vinylidene fluoride) (PVDF) exposed to $^{60}Co$ $\gamma-ray$ irradiation were investigated in correlation with the applied doses. Samples were irradiated in air at room temperature by $^{60}Co$ $\gamma-ray$ to doses in the range of 200 to 1000kGy. Various properties of the irradiated PVDF were studied using FTIR, differential scanning calorimetry (DSC), gel fraction and elongation. $^{60}Co\gamma-ray$ irradiation was found to induce changes in chemical, thermal, mechanical and structural properties of PVDF and such changes vary depending on the radiation dose.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.2
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• pp.54.1-54.1
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• 2018

Recent observational studies suggest that the environmental effects can shape the evolution of galaxies in clusters. In an attempt to better understand this process, we perform idealized radiation-hydrodynamic simulations of RAM pressure stripping on star-forming galaxies using RAMSES-RT. We find that extended HI disks are easily stripped by moderate ICM winds, while there is no significant decrease in the total mass of molecular gas. RAM pressure tends to compress the molecular gas, leading to enhanced star formation especially when the gaseous disk is hit by edge-on winds. On the other hand, strong ICM winds that are expected to operate at the centre of clusters strip both HI and molecular gas from the galaxy. Interestingly, we find that the strong ICM winds can induce the formation of relatively dense (~1H/cc) HI gas clouds at a distance from the disk.

• Journal of the Korea Institute of Military Science and Technology
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• v.5 no.2
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• pp.116-122
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• 2002

Electro Explosive Devices can be susceptible to electromagnetic interference. When these components are exposed to external electromagnetic fields, it may cause to induce sufficient current to generate enough heat for an inadvertent detonation. It is almost impossible to monitor the event of firing throughout the electromagnetic environment test. The survivability of EED for hazards of electromagnetic radiation is investigated. A fiber optic sensor is installed near the bridge wire after removing explosive material in order to measure the induced current on the bridge wire. The length of lead-wire of the EED fabricated is around 15 cm.

• The Journal of Korean Society for Radiation Therapy
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• v.9 no.1
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• pp.71-81
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• 1997

I. Objective and Importance of the Project We have been using MC-50 cyclotron and NT-50 neutron therapy machine for treating cancer patients since 1986 at Korea Cancer Center Hospital. It is mandatory to measure accurately the dose distribution and the total absorbed dose of fast neutron for putting it to the clinical use. At present the methods of measurement of fast neutron are proposed largely by American Associations of Physicists in Medicine (Task Group 18), European Clinical Neutron Dosimetry Group, and International Commission on Radiation Units and Measurements. The complexity of measurement, however, induce the methodological differences between them. In our study, therefore, we tried to establish a unique technique of measurement by means of measuring the emitted doses and the dose distribution of fast neutron beam from neutron therapy machine, and to invent a standard method of measurement adequate to our situation. II. Scope and Contents of the Project For establishing a unique technique of measurement and inventing a standard method of measurement of fast neutron beam, 1. to grasp the physical characteristics of neutron therapy machine 2. to study the principles for measrement of fast neutron beam 3. to get the dose distribution (dose rate, percent-depth dose, flatness etc) throught the actual measurement 4. to compare our data with those being cited world-widely.