• Journal of Radiation Protection and Research
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• v.26 no.2
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• pp.73-78
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• 2001

In order to find the exposure conversion coefficients for 3"X3" NaI spectrum, we measured the exposure rates with the pressurized ion chamber at 29 different areas in the range of $4{\sim}23{\mu}R\;h^{-1}$, and also measured the gamma spectra with 3"X3" and 4"X4" NaI detectors, simultaneously. The exposure conversion coefficient of the total energy method was determined using the linear relation between the measured exposure rate and the gamma spectrum energy. In order to find the exposure conversion coefficients of the energy band method, we applied the exposure conversion coefficients recommended by NCRP to the 4"X4" NaI spectra, and calculated the exposure rates due to $^{40}K,\;^{238}U$, and $^{232}Th$ series respectively. Using the linearly proportional relation between the obtained $^{232}Th$ series exposure rate and peak area of 2614 keV that represents the $^{232}Th$ series, we obtained the exposure conversion coefficients for $^{232}Th$ series. We also determined the conversion coefficients for $^{238}U$ series and $^{40}K$ using a similar method.

• Journal of Radiation Protection and Research
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• v.32 no.4
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• pp.168-177
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• 2007

A neural network model to evaluate the neutron exposure on the reactor pressure vessel inner diameter was developed. By using the three dimensional synthesis method described in Regulatory Guide 1.190, a simple linear equation to calculate the neutron spectrum on the reactor pressure vessel was constructed. This model can be used in a quick estimation of fast neutron flux which is the most important parameter in the assessment of embrittlement of reactor pressure vessel. This model also used in the selection of an optimum core loading pattern without the neutron transport calculation. The maximum relative error of this model was less than 3.4% compared to the transport calculation for the calculations from cycle 1 to cycle 23 of Kori unit 1.

• Journal of Electrical Engineering and Technology
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• v.6 no.2
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• pp.275-279
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• 2011

Sterilization of Escherichia coli (E. coli) is examined using a unique pulsed ultra-violet (UV) elliptical reactor based on Nd:YAG laser resonator, UV radiation from a pulsed xenon flashlamp. The light from the discharge has a broadband emission spectrum extending from the UV to the infrared region with a rich UV contained. Sterilization method by using the UV light is fast, environment-friendly and it does not cause secondary pollution. A Nd:YAG laser resonator having elliptical shape has advantage of concentrating the radiation of the UV light at two foci as the quart sleeve filled with E. coli. The primary objective of this research is to determine the important parameters such as pulse per second (pps), the applied voltage for sterilizing E. coli by using an UV elliptical reactor. From the experiment result, the sterilization effect of UV elliptical reactor is better than that of UV cylindrical reactor, and it can be 99.9% of sterilization at 800V regardless of the pps within 10 minutes.

• 전기의세계
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• v.23 no.5
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• pp.54-60
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• 1974

Proposals were mode on how to differentiate radiation effects in morphological phases of polyethylene and discussions were developed with the results obtained on a low density polyethylene, SOCAREX, specified by number average molecular weight; overbar Mn=5,400, density; 0.92, and degree of branch; 3.4/100 carbon atom, which was irradiated to Co$^{60}$ .gamma. ray at the dose rate of 0.5 Mrad/hr in ambient temperature under the pressure of 10$^{-5}$ Torr. or 1 atm. respectively. The effect to crystalline phase in possibly deduced from dose dependent variation of relative area between (110) and (200) peaks on X ray diffraction spectrum and that, the effects to amorphous phase can be understood through dose dependent relaxation behaviours of .betha. peak on internal friction characteristics of the specimen. The results obtained thus far indicate that, in crystalline phase, relative crystallinity shows a rather rapid decrease up to 20 Mrad with increasing dose, however, little change of crystallinity can be observed in the region between 20-200 Mrad, and degradation appears to be more predominant than crosslinking up to 60 Mrad. While in amorphous phase the indication also shows that degradation is only predominant up to 20 Mrad. Furthermore several correlations can be seen with amenable explanation between dose dependent behaviours observed in both phases.

• Journal of Radiation Protection and Research
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• v.40 no.2
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• pp.87-91
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• 2015

We have employed X-ray photoelectron spectroscopy (XPS) technique to examine the combined effects of low-energy electron (LEE) irradiation and $Fe^{3+}$ ion on DNA damage. pBR322 plasmid DNA extracted from E. coli ER2420 was used for preparing DNA-$Fe^{3+}$ sample. The C1s XPS spectra were scanned for LEE-irradiated and LEE-unirradiated samples and then curve-fitted. For the samples with LEE irradiation only or with Fe ion only, no significant changes from pure DNA samples were observed - a single effect of either $Fe^{3+}$ ion or LEE irradiation did not cause a significant damage. However, when these two components were combined, the DNA damage was increased quite significantly, compared to the sum of DNA damages caused by $Fe^{3+}$ ion and by LEE irradiation independently. This observation is consistent with our previous results [Radiat. Res. 177, 775 (2012)] which was done using gel-electrophoresis technique. Partial interpretation of the observed spectrum peaks was also attempted.

• Journal of Radiation Protection and Research
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• v.17 no.1
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• pp.31-41
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• 1992

A study for the evaluation of selected filter media that need further characterization particularily in the context of alpha measurements of radon progeny has been carried out by investigating physical characteristics and using the alpha spectroscopy. Physical characteristics was investigated by electrostatic charging and mechanical strength of filters, and then pressure drop before and after sampling was tested. Alpha spectroscopy was used to analyze the energy spectra from the deposition of radon progeny into filters. The results of the assessment showed that the newer filter types do not have a great advantage over the 'old standard' Millipore type AA. But Metricel DM-800 is recommended for those situations where electrostatic charging is a problem. Also this method will be used more effective for the evaluation of new developing filters in future.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.6 no.1
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• pp.48-65
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• 1995

This paper deals with the analysis of the unintentional radiation from the TDX-1B subscriber Board. According to the demand of digital systems and developement of high speed switching devices, electro- magnetic noise intensity and it's bandwidth occupancy in spectrum are increasing and so there is a serious possibility causing the various EMI phenomena. More accurate radiation model was established by using the Finite Difference Time Domain (FDTD) analysis, and the EMI probabilistic analysis of the digital switching system was performed. For validating the proposed model and its calculated results, on-promises test was performed and compared with the calculated results. These results may be applicable to be used for EMI model in large digital system, and prediction of EMI effect from a large digital system, and the EMI control design when designing digital system to meet inter- national EMI regulation.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1999.11a
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• pp.462-466
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• 1999

As the spectrum migrates to the higher frequency band around several milimeters wavelength for implementing wideband highspeed communications, it is more important to consider the channel attenuation characteristics of microwave signals. Microwave channels in 27GHz used in B-WLL system must be considered by compensating the power attenuation due to rainfall. So, in the design of one cell, the radiation power enhancement considering rainfall attenuation has an effort on the receiver in other cell as interference. In this paper we consider the main characteristics for B-WLL systems, optimum cell radius, and serviceable limit of heavy rainfall the design of the radiation power control system in case of enhancing the power that prevents from reducing the system capacity by interference.

• Journal of Radiation Industry
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• v.2 no.3
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• pp.141-148
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• 2008

Beta rays emitted from tritium in titanium tritide film were simulated with cathode rays of a scanning electron microscope to investigate the effect of beta rays from tritium on semiconductor devices. The cathode ray currents, which vary with the change of applied energy and beam spot size, were measured with Faraday cup. The current from the semiconductor device irradiated with cathode rays at various conditions was measured. The cathode ray current increased with the increase of spot size to a maximum then decreased when the spot sized increased further. The magnitude of current produced in the semiconductor device is proportional to the magnitude of cathode ray current. The magnitude of cathode ray current at each energy level was matched to the intensity of beta ray to simulate the tritium beta ray spectrum. Then the semiconductor characteristics were analyzed with I-V curves.

• Nuclear Engineering and Technology
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• v.54 no.12
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• pp.4715-4721
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• 2022

A comprehensive approach for modeling the pulse height spectra of gamma-ray detectors from passing radioactive cloud in a case of accident at NPP has been developed. It involves modeling the transport of radionuclides in the atmosphere using Lagrangian stochastic model, WRF meteorological processor with an ARW core and GFS data to obtain spatial distribution of radionuclides in the air at a given moment of time. Applying representation of the cloud as superposition of elementary sources of gamma radiation the pulse height spectra are calculated based on data on flux density from point isotropic sources and detector response function. The proposed approach allows us to obtain time-dependent spectra for any complex radionuclide composition of the release. The results of modeling the pulse height spectra of the scintillator detector NaI(Tl) Ø63×63 mm for a hypothetical severe accident at a NPP are presented.