• Proceedings of the Korean Nuclear Society Conference
• /
• 2001.10a
• /
• pp.298.1-298
• /
• 2001

• Proceedings of the Korean Nuclear Society Conference
• /
• 1999.05a
• /
• pp.367-367
• /
• 1999

• Proceedings of the Korean Nuclear Society Conference
• /
• 2005.10a
• /
• pp.846-847
• /
• 2005

• Korean journal of dermatology
• /
• v.56 no.9
• /
• pp.579-580
• /
• 2018

• Animal cells and systems
• /
• v.6 no.3
• /
• pp.187-193
• /
• 2002

It has long been recognized that exposure to low levels of toxic chemicals could have beneficial effects, such as increased resistance to related chemicals or stimulation of growth or development. The notion of radiation hormesis, that exposure to low levels of ionizing radiation could produce beneficial effects, developed seriously in the late 1950’s, and was, to most radiation scientists, incredible. This was due in pan to the then prevailing ideas of radiobiological mechanisms, in part to the sweeping generalizations made by the leading proponents of the radiation hormesis concept, and in pan to the many failures to confirm reports of beneficial effects. More recent understanding of the mechanisms of radiation damage and repair, and discoveries of induction of gene expression by radiation and other genotoxic agents [the adaptive response] make it seem inevitable that under suitable conditions, irradiation will produce beneficial effects.

• Journal of the Korean Data and Information Science Society
• /
• v.17 no.2
• /
• pp.581-598
• /
• 2006

In many epidemiological and medical studies, a number of cancer mortalities in categorical classification may be considered as having Poisson distribution with person-years at risk depending upon time. The cancer mortalities have been evaluated by additive or multiplicative models with regard to background and excess risks based on several covariances such as sex, age at the time of bombings, time at exposure, or ionizing radiation, cigarette smoking habits, duration of smoking habits, etc. An interest herein is to examine an additive, synergistic, or antagonistic relationship between radiation exposures and cigarette smoking habits for cancer mortalities. The results revealed a highly significant antagonistic in uence for cancer mortalities from all non-hematologic findings, lung and respiratory system with negative interaction between radiation exposures and cigarette smoking amounts.

• Korean Journal of Environmental Biology
• /
• v.26 no.1
• /
• pp.1-7
• /
• 2008

A mathematical model for the synergistic interaction of physical and chemical environmental agents was suggested for quantitative prediction of irreversibly damaged cells after combined exposures. The model took into account the synergistic interaction of agents and was based on the supposition that additional effective damages responsible for the synergy are irreversible and originated from an interaction of ineffective sublesions. The experimental results regarding the irreversible component of radiation damage of diploid yeast cells simultaneous exposed to heat with ionizing radiation ($^{60}Co$) or UV light (254 nm) are presented. It was shown that the cell ability of the liquid holding recovery decreased with an increase in the temperature, at which the exposure was occurred. A good correspondence between experimental results and model prediction was demonstrated. The importance of the results obtained for the interpretation of the mechanism of synergistic interaction of various environmental factors is discussed.

• International Journal of Aeronautical and Space Sciences
• /
• v.3 no.2
• /
• pp.40-45
• /
• 2002

A radiation analysis is performed for the Ka and Ku-band transponder of the Communications and Broadcasting Satellite (CBS) that is planned for launch into the geo-synchronous orbit. A particular attention is given to calculation of Total Ionizing Dose (TID) for the mission life time of 15 + 3 years. A numerical modeling of the charged particles at the geo-synchronous orbit is undertaken. The charged particles from the modeling are then transported through the mechanical structure and component housings of the transponder. A set of locations are selected for the detailed calculation of TID. The results from the present calculation show that three-dimensional modeling of the component housings as well as the mechanical structure of the spacecraft is requisite in order to acquire a reliable calculation of TID.

• Korean Journal of Environmental Biology
• /
• v.21 no.4
• /
• pp.384-391
• /
• 2003

The induction of chromosome aberrations in Hordeum vulgare germs after irradiation is studied for the dose range of 10 to 1,000 mGy. The relationship between the frequency of aberrant cells and the absorbed dose is shown to be non -linear and has a dose-independent plateau within the range of 56-467 mGy where the level of cytogenetic damage is statistically significantly distinguished from the spontaneous level. The comparison of the goodness of the experimental data fitting with mathematical models of different complexities, using the most common quantitative criteria, demonstrates the benefit of the piecewise linear model over the linear and polynomial ones in approximating the cytogenetical disturbance frequency. The results of our study support the conclusion about indirect mechanism of chromosome aberrations induced by low doses or dose rates mutagenesis.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.27 no.12
• /
• pp.1900-1905
• /
• 1990

In this study, the thermal neutron effects on optical fiber are examined theoretically. Also, the induced loss by thermal neutron irradiation in optical fibers is measured at the optical wavelengths of 0.85 and 1.3\ulcorner, respectively, and the results are analyzed. Thermal neutrons cause nuclear reaction with fiber compositions. So secondary ionizing radiations of high energy are generated. Color centers formed by these secondary ionizing rasiations increase transmission loss of optical fiber by absorbing propagating light in fiber core. As a result of experiment, owing to Ge, P, and B doping effects, the induced loss in multimode fibers has been 5 tmes larger than that in single mode fibers at 1.3 \ulcorner wavelengh. In case of multimode fibers, the loss at 0.8 \ulcorner wavelength region more suceptible for radiations has been twice higher than at 1.3\ulcorner.