• Journal of Radiation Protection and Research
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• v.13 no.1
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• pp.8-20
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• 1988

The annual individual and collective doses to the thyroids of four age-dependent groups due to the in-take of I-131 released from the Younggwang nuclear power plant NU-1 & 2, Korea, are estimated using the model presented in ICRP 29. Sensitivity and robustness of the model are analyzed. In case of 0.12% fuel defect during normal operation, the collective dose is founded to be 3.05${\times}10^{-3}$man-thyroid-Sv, which is higher than the value calculated by the GASPAR code, 2.3${\times}10^{-3}$man-thyroid-Sv. The maximal individual annual doses resulting from an acute release are higher than those calculated under the assumption of continuous release by $1.4{\sim}1.7$ times. The most important pathway to the infant is milk and, in contrast, that to child, teen and adult is ingestion of crops. The model used is the calculation appears to be influenced by the variables such as roubstness-index. The weighted committed dose equivalent obtained by the ICRP 29 model is slightly higher than that calculated by the three-compartment model.

• Korean Journal of Optics and Photonics
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• v.15 no.4
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• pp.385-390
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• 2004

In this paper, we designed a 4-bit optical true time-delay(TTD) for phased array antennas(PAAs), which is composed of a wavelength-fixed optical source, 2 ${\times}$ 2 optical MEMS switches, and fiber-optic delay lines. A 4-bit TTD with a unit time delay difference of 6 ps for 10-GHz PAAs has been implemented. Measurement results on time delay show an error of -0.4 ps at maximum, corresponding to a radiation angle error of less than 1.63$^{\circ}$. Thus, the TTD implemented in this research performs in excellent agreement with theory. Each TTD line, composed of MEMS switches and fiber-optic delay lines, connected to the corresponding antenna element has insertion loss in between 1.36 ㏈ and 2.40 ㏈ depending upon the setup of the switches. On the other hand, the insertion loss difference between TTD lines was 0.32 ㏈ at maximum for a fixed radiation angle. The TTD structure proposed in this paper might be more reliable and economical than those previously proposed using tunable wavelength sources if proper power equalization either with gain control of RF amplifiers or variable attenuators is achieved.

• Journal of Radiation Protection and Research
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• v.28 no.4
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• pp.271-279
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• 2003

Soil blocks were taken into culture boxes from 12 paddy fields within 5 km radii of Yonggwang and Ulchin NPPs and $^{90}Sr$ was applied to the surface water at a pre-transplanting stage and $1{\sim}2$ days before the start of heading. Following the pre-transplanting application, transfer factors were investigated for $2{\sim}4$ years. In the year of application, transfer factors $(m^2\;kg^{-1}-dry)\;of\;^{90}Sr$ applied before transplanting, showing no regionally distinguishable trend, varied with soils by a factor of about 2 with averages of $2.6{\times}10^{-4}$ for hulled seeds and $1.3{\times}10^{-2}$ for straw Transfer factors of $^{90}Sr$ applied shortly before heading were about 2 times greater than those applied before transplanting. Transfer factors tended to decrease with increasing soil pH and exchangeable Ca. Generic values of $^{90}Sr$ transfer factors in the year of deposition were proposed for the Korean paddy fields. In the second year compared with the first year, the transfer factor decreased more in Ulchin soils, which were on the whole higher in sand content, than in Yonggwang soils. For Yonggwang soils as a whole, the annual decrease in transfer factor was well described by an exponential equation with a half-life of about 2.2 years.

• Journal of Radiation Protection and Research
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• v.30 no.2
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• pp.55-60
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• 2005

The evaluation of neutron flux distribution was performed for the ex-core detector design of SMART-P. DORT and MCNP code were used for the calculation of energy-dependent neutron flux distribution at 100% full power condition. Two code results show that maximum thermal flux appears at the $1^{st}$ water region in IST region and agree within 10% difference. In addition, another evaluation was performed code with assumptions that cote was composed of fission source and control rod without fuel assemblies. These assumptions make neutron count rate to be minimized. As a results, maximum thermal flux showed $6.99{\times}10^{-2}(n/cm^2-sec)$, when the strength of initial fission source was assumed as $1.0{\times}10^8(n/sec)$. The main reason of these results is due to the thermalization of fast neutrons in the water region and thermal flux is proportional to 80% of total neutron flux. Therefore, optimization of filler material of detector guide tube, position of installation and axial length of detector segments is necessary for the design of ex-core detector to enhance the neutron count rate and above results could be used in ex-core detector design as a fluence requirement.

• Journal of Radiation Protection and Research
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• v.38 no.4
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• pp.228-233
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• 2013

It has been continuously generated the requirement for the replacement of the main components such as a steam generator due to the deterioration of the nuclear power plant all around the world. Also, a large amount of radioactive metal was generated during the decommissioning in a short period. It is required to make an accurate measurement of the residual radioactivity for recycling the metal waste for releasing from regulatory control. In planning the measurement procedures, the influence of geometry, self-absorption, density and other relevant factors on the representativeness of the measurements should be considered for the decommissioning metal waste. In this study, the method for measurement procedures, the source term evaluation, the ways to secure representative samples, the measurement device for wide area and the self-absorption correction factors for different density were evaluated. The metal samples for measurement were prepared for securing the simple geometry and representative by melting process. The developed correction method for measuring the radioactivity a variety density of metal waste could improve the reliability of the evaluation results for clearance.

• Journal of Radiation Protection and Research
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• v.42 no.2
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• pp.114-129
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• 2017

Background: The purpose of this paper is to confirm the event timings and the magnitude of fission product aerosol release from the Fukushima accident. Over a few hundreds of technical papers have been published on the environmental impact of Fukushima Daiichi accident since the accident occurred on March 11, 2011. However, most of the research used reverse or inverse method based on the monitoring of activities in the remote places and only few papers attempted to estimate the release of fission products from individual reactor core or from individual spent fuel pool. Severe accident analysis code can be used to estimate the radioactive release from which reactor core and from which radionuclide the peaks in monitoring points can be generated. Materials and Methods: The basic material used for this study are the initial core inventory obtained from the report JAEA-Data/Code 2012-018 and the given accident scenarios provided by Japanese Government or Tokyo Electric Power Company (TEPCO) in official reports. In this research a forward method using severe accident progression code is used as it might be useful for justifying the results of reverse or inverse method or vice versa. Results and Discussion: The release timing and amounts to the environment are estimated for volatile radioactive fission products such as noble gases, cesium, iodine, and tellurium up to 184 hours (about 7.7 days) after earthquake occurs. The in-plant fission product behaviors and release characteristics to environment are estimated using the severe accident progression analysis code, MELCOR, for Fukushima Daiichi accident. These results are compared with other research results which are summarized in UNSCEAR 2013 Report and other technical papers. Also it may provide the physically based arguments for justifying or suspecting the rationale for the scenarios provided in open literature. Conclusion: The estimated results by MELCOR code simulation of this study indicate that the release amount of volatile fission products to environment from Units 1, 2, and 3 cores is well within the range estimated by the reverse or inverse method, which are summarized in UNSCEAR 2013 report. But this does not necessarily mean that these two approaches are consistent.

• Journal of Radiation Protection and Research
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• v.39 no.2
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• pp.89-95
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• 2014

In potential accident consequence assessments for the licensing approval of LWRs, the ground deposition of radionuclides released into the environment is not allowed into the models, as recommended in the U. S. Nuclear Regulatory Commission's regulatory guide. Meanwhile, it is allowed into the assessment models for the licensing approval of PHWRs with consideration of more detailed physical processes of radionuclides in the atmosphere. Under these backgrounds, importance of exposure dose by ground deposition was quantitatively evaluated and comprehensively discussed. For potential accidental releases of $^{137}Cs$ and $^{131}I$, total exposure doses were more conservative in case of without consideration of ground deposition than in case of with its consideration. It was because of that the depletion of air concentration resulting from ground deposition is more influential in the contribution to total exposure doses than additional doses from contaminated ground. The exposure doses by the inhalation of contaminated air showed the contribution of more than 90% in total exposure doses, depending on atmospheric stability, release period of radionuclides and distance from a release point. The exposure doses from contaminated ground showed less than 10% at most in contribution of total exposure doses. The ratios of total exposure doses in case of with consideration of deposition to without its consideration for $^{131}I$ were distinct than those for $^{137}Cs$. As the atmosphere is more stable, release duration of radionuclides is longer, distance from a release point is longer, it was more distinct.

• Journal of Radiation Protection and Research
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• v.31 no.3
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• pp.141-148
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• 2006

Surveys of radioactive contamination were performed for imported foodstuffs in 2003. The following samples among imported foodstuffs were selected from markets and Korea Food and Drug Administration(KFDA); the imported samples from country associated with the Chernobyl nuclear accident, the samples produced around the nuclear power plants or nuclear tests, the foodstuffs reported as radioacitive contamination materials in foreign country. After pretreatments such as drying and homogenization, samples were analyzed. The $^{137}Cs$ radionuclide was only measured among the regulation radionuclides($^{137}Cs,\;^{134}Cs,\;^{131}I$) of food code. All foodstuffs except Inonotus Obliquus(Chaga mushooms) are less than 17.0 Bq/kg or below the minimum detectable activity(MDA). The activity concentrations of Chaga mushrooms from Russia ranged up to 131.25 Bq/ltg which is almost 35 % of the maximum permitted level of food code. The fraction of imported foodstuffs having meaningful radioactivity is small, however, the radioactive contamination survey of imported foodstuffs is still needed.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.7 no.4
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• pp.188-194
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• 2014

In this paper, an antenna which has quad band in LTE (0.746 ~ 0.798 GHz), GSM(0.824 ~ 0.960 GHz), DCS(1.71 ~ 1.88 GHz), WCDMA(1.91 ~ 2.17 GHz) is proposed. An antenna size is $122mm{\times}50mm{\times}0.8mm$ on FR4(${\epsilon}_r=4.4$) ground substrate. In the proposed antenna, branch line is applied to the conventional PIFA architecture to achieve multi-bandwidth. Coupling power supply is applied for a wide bandwidth. Result of the measurement is as follows. When the low frequency, the antenna presents gain of 0.93 ~ 1.92dBi, and radiation efficiency of 49.60 ~ 76.35 %, and When the high frequency, gain is 2.19 ~ 4.66dBi, and radiation efficiency is 60.40 ~ 80.01 %, and with a VSWR < 2 (${\leq}-10dB$)measurement results for standard satisfies all band. Judging from the result, proposed multiband antenna is expected to be applied. B4G mobile terminals since the antenna shows an outstanding performance.

• The Journal of Fisheries Business Administration
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• v.50 no.2
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• pp.23-40
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• 2019

The main purpose of this study is to analyze and examine the problems of the law systems of the safety and maintenance of nuclear facilities and to propose the improvements with respect to the related problems especialy focused on safety management of aquatic products. Therefore, the results of the paper would be helpful to build an effective management law system of safety and maintenance of nuclear facilities and fisheries products. The research methods are longitudinal and horizontal studies. This study compares domestic policies with foreign policies of nuclear plants and aquatic products. Using the above methods, examining the current system of nuclear-related laws and regulations, we have found that there exist 13 Acts including "Nuclear Safety Act", etc. Safety laws related on nuclear facilities have seven Acts including "Nuclear Safety Act", "the Act on Physical Protection and Radiological Emergency", "Radioactive waste control Act", "Act on Protective Action Guidelines against Radiation in the Natural Environment", "Special Act on Assistance to the locations of facilities for disposal low and intermediate level radioactive waste", "Korea Institute of Nuclear Safety Act". "Act on Establishment and Operation of the Nuclear Safety and Security Commission". The seven laws are composed of 119 legislations. They have 112 lower statute of eight Presidential Decrees, six Primeministrial Decrees and Ministrial Decrees, 92 administrative rules (orders), 6 legislations of local self-government aself-governing body. The concluded proposals of this paper are as follows. Firstly, we propose that the relationship between the special law and general law should be re-established. Secondly, the terms with respect to law system of safety and maintenance of nuclear plants should be redefined and specified. Thirdly, it is advisable to re-examine and re-establish the Law System for Safety and Maintenance of Nuclear Facilities. and environmental rights like the French Nuclear Safety Legislation. Lastly, inadequate legislation on the aquatic pollution damage should be re-established. It is necessary to ensure sufficient transparency as well as environmental considerations in the policy decisions of the Korean government and legislation of the National Assembly. It is necessary to further study the possibilities of accepting the implications of the French legal system as a legal system in Korea. In conclusion, the safety management of nuclear facilities is not only focused on the secondary industry and the tertiary industry centering on power generation and supply, but also on the primary industry, which is the food of the people. It is necessary to prevent damage to be foreseen. Therefore, it is judged that there should be no harm to the people caused by contaminated marine products even if the "Food Safety Law for Prevention of Radiation Pollution Damage" is enacted.