• 한국방사선학회논문지
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• 제14권4호
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• pp.425-431
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• 2020

COVID-19로 인해 수출용 컨테이너에 방사선 발생 장치를 설치한 경우 방사선실의 공간선량을 측정하고 검사실 내의 차폐벽의 효용성에 대하여 연구하고자 하였다. 측정 지점은 X-선관에서 검사자가 있는 뒤쪽으로 이동식 차폐벽을 사용하지 않았을 때를 12곳을 측정하였으며, 이와 대조군으로 이동식 차폐벽을 사용한 후 차폐벽 뒤에서 3곳을 측정하였다. 측정은 Survey Meter를 켜고 배후 방사선(Background)을 측정하였고, 배후 방사선(Background)에서 측정 Peak치 값을 빼서 산출하였다. 이동식 차폐벽 없이 X-선관 뒤, 50cm, 100cm, 200cm로 설정하여 12 곳을 측정하였고, 이동식 방사선 차폐벽을 사용하여 X-선관 뒤에서 3곳을 측정하여 이동식 방사선 차폐벽의 사용 전후의 선량값을 비교하였다. 이동식 차폐벽의 사용 여부에 따라 측정된 선량의 평균값을 대응표본 t 검정을 통하여 결과값 p < 0.05(양측)로 검증하였다. 측정값은 X-선관 뒤 좌측 50cm : 1.446μSv, X-선관 뒤 : 0.545μSv, X-선관 뒤 우측 50cm : 1.466μSv, 방사선 방어용 벽 뒤에서 측정값은 0.190μSv, 0.204μSv, 0.191μSv였다. 실측한 결과 검사실 내에서의 차폐벽으로 인한 검사자의 의료 피폭은 82.3%로 감소시킬 수 있었다. 선별 방사선 검사실에서의 직업 피폭을 감소시키기 위해서는 방사선 발생원으로부터 충분한 이격과 차폐벽의 사용을 권고하는 바이다.

• 대한방사선기술학회지:방사선기술과학
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• 제38권3호
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• pp.237-244
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• 2015

핵의학 종사자는 PET/CT 업무 환경 중 방사성 의약품 취급 시 상당히 높은 피폭선량을 받는다고 알려져 있으며, 이를 최소화하기 위해 적절한 차폐기구의 사용이 요구된다. 이에 본 연구에서는 몬테카를로 기법을 기반으로 한 모의실험과 실측을 통해 18F-FDG 선원 취급 시 Apron 착용에 대한 차폐효과에 대해 분석하였다. 그 결과, 모의실험의 경우 선원의 취급 위치에 따라 인체 장기별 선량 분포가 각각 다른 양상을 나타냈고, Apron 납 두께별 선량 감소율은 선원과 장기와의 위치가 근접할수록, 선원과의 접촉 거리가 멀수록 낮은 경향을 나타냈다. 선량 측정 장비를 통한 실측의 경우, 측정 장비간 특성으로 인해 평균 공간 선량률 분포는 상이한 결과를 보였으나, 거리별 납 당량의 증가에 따라 지수함수분포로 공간 선량률이 감소되었다.

• 대한방사선기술학회지:방사선기술과학
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• 제41권5호
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• pp.397-403
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• 2018

Mobile X-ray generators are used not in the radiation area but in open space, which causes the exposure of secondary radiation to the healthcare professionals, patients, guardians, etc., regardless of their intentions. This study aimed to investigate the shielding effect of the developed radiation restrictor to block the secondary radiation scattered during the use of mobile X-ray generator. Upon setting the condition of mobile X-ray generator with chest AP, spatial doses were measured by the existence of human equivalent phantom and radiation restrictor, and measured by the existences of phantom and radiation restrictor at the same length of 100 cm. Measurements were taken at intervals of 10 cm every $30^{\circ}$ from $-90^{\circ}$ (head direction) to $+90^{\circ}$ (body direction). Upon the study results, spatial doses in all direction were increased by 45% on average when using phantom in the same condition, however, they were decreased by 64% on average when using the developed radiation restrictor. The dose at 100 cm from the center of X-ray was $3.0{\pm}0.08{\mu}Gy$ without phantom and was increased by 40% with $4.2{\pm}0.08{\mu}Gy$ after phantom usage. The dose when using phantom and the developed radiation restrictor was $1.4{\pm}0.08{\mu}Gy$, which was decreased by 66% compared to the case without using them. Therefore, it is considered the scattered radiation can be shielded at 100-150 cm, the regulation of the distance between beds, effectively with the developed radiation restrictor when using mobile X-ray generators, which can lower the radiation exposure to the people nearby including healthcare professionals and patients.

• 한국정보통신학회논문지
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• 제24권9호
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• pp.1132-1137
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• 2020

유방 X선 촬영 장치를 이용한 유방 촬영을 실시할 때 발생되는 불필요한 피폭 선량을 경감시키기 위해 비스무스로 제작한 차폐체를 촬영 부위의 반대 측 유방에 적용했을 때 차폐율 분석을 실시하였다. 오른쪽, 왼쪽을 압박하였을 때 CC와 MLO 검사 시 압박되지 않는 유방의 산란 선량을 알아보기 위하여 비스무스를 차폐하지 않았을 때(Not used : NU그룹)와 차폐했을 때(Used : U그룹)로 구분하여 실험을 진행하였다. NU 그룹의 평균선량은 9.568μSv이었고, U그룹의 평균 선량은 1.038μSv이었다. 비스무스 차폐체 사용 전후의 평균 측정 선량은 89.15% 감소되었다. 유방 촬영용 비스무스 차폐체를 사용하면 산란 방사선을 차폐하여 방사선에 의한 노출을 최소한으로 유지할 수 있다.

• Nuclear Engineering and Technology
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• 제54권1호
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• pp.269-274
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• 2022

An artificial neural network (ANN) that identifies radionuclides from low-count gamma spectra of a NaI scintillator is proposed. The ANN was trained and tested using simulated spectra. 14 target nuclides were considered corresponding to the requisite radionuclide library of a radionuclide identification device mentioned in IEC 62327-2017. The network shows an average identification accuracy of 98.63% on the validation dataset, with the gross counts in each spectrum N_c = 100~10000 and the signal to noise ratio SNR = 0.05-1. Most of the false predictions come from nuclides with low branching ratio and/or similar decay energies. If the N_c>1000 and SNR>0.3, which is defined as the minimum identifiable condition, the averaged identification accuracy is 99.87%. Even when the source and the detector are covered with lead bricks and the response function of the detector thus varies, the ANN which was trained using non-shielding spectra still shows high accuracy as long as the minimum identifiable condition is satisfied. Among all the considered nuclides, only the identification accuracy of ²³⁵U is seriously affected by the shielding. Identification of other nuclides shows high accuracy even the shielding condition is changed, which indicates that the ANN has good generalization performance.

• 대한방사선기술학회지:방사선기술과학
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• 제46권6호
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• pp.519-526
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• 2023

This study was intended to evaluate the shielding rate of radiation shields manufactured using 3D printers that have recently been used in various fields by comparing them with existing shields made of lead, and to find out their applicability through experiments. A 3D printer shield made of tungsten filament 1 mm, 2 mm, 4 mm shield, RNS-TX (nanotungsten) 1.1 mm, lead 0.2 mmPb, and 1mmPb were exposed to ^99mTc, ¹⁸F, and ²⁰¹TI for 15, 30, 45 minutes, and 60 minutes after measuring cumulative dose three times. Based on this, the shielding rate of each shield was calculated based on the dose in the absence of the shield. In addition, ^99mTc, ¹⁸F, and ²⁰¹TI were located 100 cm away from the phantom in which the OSLD nano Dot device was inserted, and if there was no shield for 60 minutes, the dose of thyroid was measured using 1.0 mm of lead shield, 1.1 mm of RNS-TX shield, and 2 mm of tungsten shield made by 3D printer. The use of shields during radiation shielding emitted from open radiation sources all resulted in a reduction in dose. The radiation dose emitted from the radionuclides under the experiment was all reduced when the shield was used. This study has been confirmed that tungsten is a material that can replace lead due to its excellent performance and efficiency as shield, and that it even shows the possibility of manufacturing a customized shield using 3D printer.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.1585-1589
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• 2007

The HANARO, a 30 MW multi-purpose research reactor in Korea, will be equipped with a neutron guide system, in order to transport cold neutrons from the neutron source to the neutron scattering instruments in the neutron guide hall near the reactor building. The neutron guide system of HANARO consists of the in-pile plug assembly with in-pile guides, the primary shutter with in-shutter guides, the neutron guides in the guide shielding room with dedicated secondary shutters, and the neutron guides connected to the instruments in the neutron guide hall. The functions of the in-pile plug assembly are to shield the reactor environment from a nuclear radiation and to support the neutron guides and maintain them precisely oriented. The primary shutter is a mechanical device to be installed just after the in-pile plug assembly, which stops neutron flux on demand. This paper describes the mechanical design of the in-pile plug assembly and the primary shutter for the neutron guide system at HANARO. The design of the guide shielding assembly for the primary shutter and the neutron guides is also presented.

• Journal of Welding and Joining
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• 제18권3호
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• pp.83-88
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• 2000

Laser cladding processing allows rapid transfer of heat to the material being processed with minimum conduction into base metal, resulting in low total heat input. The effects of Nd:YAG laser cladding with wire feeding on the mechanical properties of Inconel alloy were investigated. inconel alloy is used as the material of nuclear steam generator tubing because of its mechanical properties and corrosion resistance properties. The device for Nd:YAG laser cladding with wire feeding was designed. It consists of the wire feeding system, the wire cladding system and the shielding gas system which prevents the clad layer from being oxidized. Experimental as results indicated that the wire feeding direction and position were important for laser cladding with wire feeding. The wire feeding speed should be adapted according to cladding speed for good shaping of clad layer. The effect of heat on the HAZ size can be limited and the growth of grain size of HAZ size was not serious. The hardness of clad layer and heat affected zone increased with increasing of cladding speed.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 춘계학술대회논문집
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• pp.496-499
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• 2008

The noise reducing devices installed on the noise barrier have been developed in many shapes and ways to reduce noise around road traffic areas. In this study, test and estimation method for the noise reducing device witch installed on the top of a noise barrier was suggested. For this, the authors have considered sound power flow around the device and sound pressure levels for the far field area. To estimate the area effect behind the barrier, area average of noise pressure level difference divided by two area, upper and bellow the sight-line. Comparing the attenuation difference of these areas, the tendency of noise reduction effect was studied according to type of noise reducing devices. Compared with noise shielding efficiency of the devices that using equivalent height of a simple barrier calculated by the SoundPlan, the commercial environment noise simulation software.

• 한국방사선학회논문지
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• 제14권5호
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• pp.635-642
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• 2020

본 연구에서는 자동노출제어장치(automatic exposure control, AEC)의 채광창 차폐정도와 농도, 감도가 관전류량과 영상품질에 미치는 영향을 분석하였다. 실험에 사용된 장비는 X선관과 간접방식의 디지털검출기가 일체형인 디지털방사선발생장치(Digital Diagnost, Philips, Netherlands)를 사용하였다. 채광창 차폐정도는 3 mm 두께의 납을 이용하여 0%부터 100%까지 12.5%씩 순차적으로 누적 차폐하여 9단계로 구분하였다. 농도는 제조사에서 제시한 3단계(+2.5, 0, -2.5)와 감도 3단계(S200, S400, S800)를 대상으로 하였다. 관전류량 평가는 관전압을 40 kVp로 고정하고 AEC 조절인자들이 교차한 81가지의 조합조건에서 자동 노출된 관전류량을 측정하였다. 영상품질평가는 자체 제작한 원뿔형 피라미드 팬텀의 방사선영상을 육안 평가하여 유효한 영상을 선발하였고 이들의 신호 대 잡음비(signal to noise ratio, SNR)을 측정하였다. 그 결과 관전류량은 채광창 차폐정도가 100%, 감도 S200, 농도 2.5일 때 60.0 mAs로 가장 많이 조사되었으며, 채광창 차폐정도가 0%, 감도 S800, 농도 -2.5일 때 0.9 mAs로 가장 적게 조사되었다. SNR은 채광창 차폐정도가 0%, 감도 S200, 농도 2.5일 때 25.2로 가장 우수하였고, 채광창 차폐정도가 25%, 감도 S800, 농도 -2.5일 때 SNR이 4.7로 가장 낮았다.