• 대한방사선기술학회지:방사선기술과학
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• 제45권1호
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• pp.49-55
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• 2022

This study is to develop a mobile type environmental radiation measurement system for emergency response or environmental radiation monitoring of local governments near nuclear facilities. A mobile radiation measurement system can monitor radiation by field beyond the spatial constraints of a fixed environmental radiation monitor. If installed in local government infrastructure such as public transportation, environmental radiation can be monitored without additional manpower and measurement work. In addition, it is designed to enable monitoring and measurement of radiation from low to high doses as well as the environment in preparation for radioactive disasters such as nuclear power plant accidents. It is expected that this system will be utilized not only in normal times but also in the event of a radiation accident to improve the disaster prevention capabilities of local governments.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.1493-1498
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• 2004

WSGGM with gray gas regrouping is successfully applied to study the flame structure of counter flow flames including effect of radiative transfer. The statistical narrow band model is used to obtain the benchmark solutions. Results obtained by using the optically thin model are shown to overestimate the emission and to predict the flame structures inadequately especially for optically thick and low stretch rate flames. Computed results by using the WSGGM with 10 gray gases and SNB model show reasonable agreements with each other, and the required calculation time for the WSGGM is acceptable for engineering applications.

• 제어로봇시스템학회논문지
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• 제20권6호
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• pp.625-630
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• 2014

Asynchronous digital circuits working in military and space environments are often subject to the adverse effects of radiation faults. In this paper, we propose a new hardening technique against radiation faults. The considered digital system has the structure of DMR (Double Modular Redundancy), in which two sub-systems conduct the same work simultaneously. Based on the output feedback, the proposed scheme diagnoses occurrences of radiation faults and realizes immediate recovery to the normal behavior by overriding parts of memory bits of the faulty sub-system. As a case study, the proposed control scheme is applied to an asynchronous dual ring counter implemented in VHDL code.

• Journal of Radiation Protection and Research
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• 제26권3호
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• pp.155-159
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• 2001

Beta radiation is measured for an environmental monitoring purpose or for an internal radiation exposure monitoring of nuclear power plant's worker. In korea, strontium 89 and strontium 90 is measured for an environmental monitoring purpose. Also tritium and carbon 14 contained in urine is measured for an internal radiation exposure monitoring of nuclear power plant's worker. Because above isotopes emits low energy beta radiations having a wide range of energy, very complicated isotope separation preprocess is needed. In this study, two mixed beta emitting isotopes are measured simultaneously using a liquid scintillation counter(LSC) and analyzed by using a developed statistical method. Banded least square method is used to analyze the mixed spectrum, and the goodness-of-fitness test is proposed. Test results show that the developed procedure can be very useful for analyzing a mixed beta emitting isotopes.

• 한국농공학회지
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• 제36권2호
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• pp.88-95
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• 1994

This paper is to evaluate the applicability of neural networks to the estimation of evapotranspiration. Two neural networks were developed to forecast daily evapotranspiration of the rice crop with back-propagation and counter-propagation algorithm. The neural network trained by back-propagation algorithm with delta learning rule is a three-layer network with input, hidden, and output layers. The other network with counter-propagation algorithm is a four-layer network with input, normalizing, competitive, and output layers. Training neural networks was conducted using daily actual evapotranspiration of rice crop and daily climatic data such as mean temperature, sunshine hours, solar radiation, relative humidity, and pan evaporation. During the training, neural network parameters were calibrated. The trained networks were applied to a set of field data not used in the training. The created response of the back-propagation network was in good agreement with desired values and showed better performances than the counter-propagation network did. Evaluating the neural network performance indicates that the back-propagation neural network may be applied to the estimation of evapotranspiration of the rice crop. This study does not provide with a conclusive statement as to the ability of a neural network to evapotranspiration estimating. More detailed study is required for better understanding and evaluating the behavior of neural networks.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2004년도 학술논문집
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• pp.419-424
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• 2004

방사성 폐기물 중에 함유된 핵종 및 방사능을 측정하기 위해서는 여러 가지 방사선 계측기가 이용되고 있다. 본 연구에서는 각각의 핵종에 대하여 측정 가능한 검출기를 선정하고 원전 방사성폐기물 중 방사능을 측정 하기위한 시스템을 구성하였다. 그리고 그 계측 시스템의 바탕 값 및 계측효율을 주기적으로 측정하고 품질관리를 위한 관리도를 작성하여 계측기의 안전성을 확보하고 분석결과에 대한 신뢰도를 향상시키고자 하였다. Gamma spectrometer의 바탕 값 평균은 1.59 cps이었으며 표준 시료에 대한 평균값은 45,248 dps로 거의 대부분의 측정값이 $2{\sigma}$ 이내에서 크게 벗어나지 않음을 나타냈다. Low background ${\alpha}/{\beta}$ counting 시스템의 알파 바탕 값 평균은 0.31 cpm이고 알파선 계측효율은 34.38% 이었으며, 베타 바탕 값은 1.3 cpm이고 베타선 계측효율 46.5% 이었다. 또한 액체섬광계수기는 3H 영역에서 바탕 값이 2.52 cpm, 계측효율 58.5% 이었으며, 14C 영역에서의 바탕 값은 3.31 cpm 이었고 계측효율은 95.6% 이었다. 본 연구에서는 바탕 값 및 계측효율로부터 최소검출방사능을 설정함으로써 시료의 측정 가능한 범위를 구하였다. 측정결과, gamma spectrometer의 최소검출방사능은 3.2 Bq/$m\ell$이었으며, ${\alpha}/{\beta}$counting 시스템의 경우는 알파 및 베타 영역에서 각각 20.5 Bq/$m\ell$, 23.0 Bq/$m\ell$이고 liquid scintillation counter의 경우는 3.8 Bq/$m\ell$로 나타났다.

• Journal of Astronomy and Space Sciences
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• 제37권4호
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• pp.229-236
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• 2020

There has been increasing necessity of more precise prediction and measurements of aviation radiation in Korea. For our air crew and passengers' radiation safety, we develop our own radiation prediction model of KREAM. In this paper, we validate the KREAM model based on comparison with Liulin observations. During early three months of this year, we perform total 25 experiments to measure aviation radiation exposure using Liulin-6K in commercial flights. We found that KREAM's result is very well consistent with Liulin observation in general. NAIRAS shows mostly higher results than Liulin observation, while CARI-6M shows generally lower results than the observations. The percent error of KREAM compared with Liulin observation is 10.95%. In contrast, the error for NAIRAS is 43.38% and 22.03% for CARI-6M. We found that the increase of the altitude might cause sudden increase in radiation exposure, especially for the polar route. As more comprehensive and complete analysis is required to validate KREAM's reliability to use for the public service, we plan to expand these radiation measurements with Liulin and Tissue Equivalent Proportional Counter (TEPC) in the near future.

• Journal of Radiation Protection and Research
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• 제29권4호
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• pp.269-273
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• 2004

고계수율 환경에서의 G-M 계수기의 가용 범위를 확장하기 위하여 두 가지 불감시간(연장가능 및 연장불능)을 채택한 복합 모형이 개발되었으며, 이 복합모형 참 계수율과 실측 계수율간의 상관관계를 보다 정확히 설명한다. 이 논문에서는 몬테칼로 모사법에 근거한 G-M 계수기 불감효과 분석 프로그램 GMSIM을 개발하여 연장가능 불감시간 모형 및 연장불능 불감시간 모형에 적용하여 그 정확도를 확인하였다. GMSIM을 이용하여 복합 불감시간 모형을 따르는 G-M 계수기의 계수 통계 특성을 분석한 결과, 두 가지 이상적 모형의 중간적 특성을 보였다. 향후 GMSIM은 세 가지 모형의 불감시간 특성을 분석하는데 사용될 수 있다.

• 대한기계학회논문집
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• 제19권3호
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• pp.858-867
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• 1995

Characteristics of premixed flames in counter-flow system are numerically studied using a detailed chemical reaction mechanism including gas phase radiation. Without radiation effect accounted, low CO and high NO$_{x}$ emission indices are observed, when strain rate decreases, due to increased residence time and higher flame temperature. Higher NO$_{2}$ production has been also observed when two premixed flames are interacting or cold air stream is mixed with burned gas. The rate of NO$_{x}$ production and destruction is dependent upon the diffusional strength of H and OH radicals, the existence of NO and the concentration of HO$_{2}$. For radiating flames, the peak temperature and NO$_{x}$ production rate decreases as the strain rate decreases. At high strain rate, it is found that the effect of radiation on flame is little due to its negligible radiating volume. It is also found that NO$_{x}$ production from the interacting premixed flame is reduced due to reduced temperature resulting from radiation heat loss. It is concluded that the radiation from gas has significant effect of flame structure and on emission characteristics.ristics.

• Journal of Radiation Protection and Research
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• 제23권2호
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• pp.65-74
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• 1998

저 준위방사능 계측에서 가장 기본적으로 요구되는 것이 최적 측정시간의 결정이다. 최적화된 계측전략으로 측정시간을 결정하기 위하여 측정시간을 고정하는 방법, 측정값을 고정하는 방법, 시료와 자연계수율 또는 기준준위를 비교하여 측정하는 방법을 비교 검토하는 결정식을 도출하였다. 이 계측전략에서 기기에 주어진 측정조건 즉, 검출기의 효율, 측정기의 용량, 측정기의 최대 및 평균 자연계수율과 관련기준 즉, 기준준위, 검출한계 등을 만족하는 측정시간이 결정된다. 계측전략은 측정시 주어진 조건에서 방사능 존재확인과 정량분석에 대한 시료의 최적 측정시간의 결정을 편리하게 함으로써 일상의 저준위방사능 측정에 유용하게 사용될 것이다.