• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2019년도 춘계학술논문요약집
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• pp.347-348
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• 2019

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2018년도 추계학술논문요약집
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• pp.509-510
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• 2018

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2018년도 춘계학술논문요약집
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• pp.401-402
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• 2018

• Journal of Radiation Protection and Research
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• 제44권2호
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• pp.53-63
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• 2019

Background: As neutron fields are always accompanied by gamma rays, it is essential to distinguish neutrons from gamma rays in the detection of neutrons. Neutrons and gamma rays can be separated by pulse shape discrimination (PSD) methods. Recently, we performed characterization of a stilbene scintillator detector and an EJ-301 liquid scintillator detector with a high-speed digitizer DT5730 and investigated optimized PSD variables for both detectors. This study is for providing a basis for developing fast neutron/gamma-ray dual-particle imager. Materials and Methods: We conducted PSD experiments using stilbene scintillator and EJ-301 liquid scintillator and evaluated neutron and gamma ray discriminability of each PSD method with a $^{137}Cs$ gamma source and a $^{252}Cf$ neutron source. We implemented digital signal processing techniques to apply two PSD methods - the charge comparison (CC) method and the constant time discrimination (CTD) method - to distinguish neutrons from gamma rays. We tried to find optimized PSD variables giving the best discriminability in a given experimental condition. Results and Discussion: For the stilbene scintillator detector, the charge comparison method and the constant time discrimination method both delivered the PSD FOM values of 1.7. For the EJ-301 liquid scintillator detector, both PSD methods delivered the PSD FOM values of 1.79. With the same PSD variables, PSD performance was excellent in $300{\pm}100keVee$, $500{\pm}100keVee$, and $700{\pm}100keVee$ energy regions. This result shows that we can achieve an effective discrimination of neutrons from gamma rays using these scintillator detector systems. Conclusion: We applied both PSD methods to a stilbene and a liquid scintillator and optimized the PSD performance represented by FOM values. We observed a good separation performance of both scintillators combined with a high-speed digitizer and digital PSD. These results will provide reference values for the dual-particle imager we are developing, which can image both fast neutrons and gamma rays simultaneously.

• Nuclear Engineering and Technology
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• 제52권6호
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• pp.1271-1276
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• 2020

The geometrical efficiency of a source-to-detector configuration is considered to be necessary in the calculation of the full energy peak efficiency, especially for NaI(Tl) and HPGe gamma-ray spectroscopy detectors. The geometrical efficiency depends on the solid angle subtended by the radioactive sources and the detector surfaces. The present work is basically concerned to establish a new mathematical approach for calculating the solid angle and geometrical efficiency, based on conversion of the geometrical solid angle of a non-axial radioactive point source with respect to a circular surface of the detector to a new equivalent geometry. The equivalent geometry consists of an axial radioactive point source with respect to an arbitrary elliptical surface that lies between the radioactive point source and the circular surface of the detector. This expression was extended to include coaxial radioactive circular disk source. The results were compared with a number of published data to explain how significant this work is in the efficiency calibration procedure for the γ-ray detection systems, especially in case of using isotropic radiating γ-ray sources in the form of point and disk shapes.

• 한국방사선학회논문지
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• 제9권1호
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• pp.55-59
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• 2015

양성자핵반응에 대한 연구는 현재 핵융합로의 재료 개발을 비롯하여 양성자치료 분야 등을 중심으로 활발하게 이루어지고 있다. 본 연구는 100 MeV 양성자 빔을 이용한 $^{27}Al(p,3p+n)^{24}Na$ 반응을 통하여 발생되는 지발 감마선(2754, 1386 keV) 스펙트럼을 고순도 HPGe 검출기를 이용하여 측정하였다. 실험에 사용되어진 양성자 빔은 양성자가속기연구센터(KOMAC)에 설치되어 있는 100 MeV 양성자선형가속기를 사용하였다. 측정된 감마선은 기존에 알려진 결과들과 비교분석하였다. 측정된 감마선의 강도는 고에너지 감마선 검출효율을 결정하는데 매우 중요한 정도를 제공 할 것으로 생각되어 진다.

• 천문학회보
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• 제40권2호
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• pp.51.3-52
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• 2015

Gamma-Ray Bursts(GRBs) are the most violent event in the universe, whose detection rate is a few in a day. The spectral lag, which is commonly observed in the observed light curves of GRBs, is a difference in arrival times of the high-energy and low-energy photons. The relation between the spectral lag and the luminosity of the observed GRBs is shown to be anti-correlated in previous studies. In reported relations to date, the isotropic luminosity has been assumed. On the other hand, GRBs are likely to emit its energy through a beamed jet. In this study, we attempt to obtain the relation between the spectral lag and the collimation-corrected luminosity. We have calculated collimation-corrected luminosities and opening angles using the observed light curves taken from a database of Swift/BAT, XRT. We expect to increase its significance level by expanding a sample size compared with those previously analyzed.

• Nuclear Engineering and Technology
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• 제13권4호
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• pp.229-236
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• 1981

중성자포획 감마선 방사화분석법을 이용하여 원자로급 알루미늄중 붕소를 분석하였다. 실험에 의한 검출한계는 10% 불확실도의 경우 5.7ppm 이었다. 함량이 더욱 미량인 경우를 위하여 양이온 교환수지를 이용하며 알루미늄으로 부터 붕소를 사전분리하는 농축법을 개발하였다. 이 두 방법 즉 직접 측정하는 방법과 농축후 측정하는 두가지 방법의 정확도를 첨가법으로 조사하였다. 그 결과 5% 편차 이내에서 잘 일치하였다.

• 천문학회보
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• 제38권1호
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• pp.69.2-69.2
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• 2013

The direct detection of gravitational wave has a very important meaning as a basis for verification of the theory of relativity. Several laser interferometer detectors have attempted to detect GW directly (e.g. LIGO, VIRGO), but positional accuracy of GW detector is too wide (about 10~100sq deg) to find which objects emit GW. One of the main sources of GW is gamma-ray burst which can be detected even in electromagnetic wave. Then to verify Gamma-ray burst object as a GW source, we proceed EM follow-up observation with wide field of view. A first program initiating EM follow-ups to possible transients GW events has been developed and exercised by LIGO and VIRGO community in association with several partners. Using QUEST optical data, we tested the method of cross-convolution recommended by EM follow-up community. We will describe the results of that test.

• 한국의학물리학회:학술대회논문집
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• 한국의학물리학회 2004년도 제29회 추계학술대회 발표논문집
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• pp.69-71
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• 2004

양성자 치료는 양성자 빔의 선량분포 특성인 브래그 피크를 이용한 방사선 치료방법으로 기존의 전자 및 광자빔을 이용하는 방사선 치료와 비교하여 정상세포에는 현저히 적은 선량을 주고, 암세포에는 대부분의 선량을 줄 수 있어 최근에 각광받고 있다. 양성자 치료 빔은 치료 부위에서 완전히 멈추고 인체 내 각기 다른 밀도를 가진 장기들에 의해 양성자 빔의 비정이 불확실하기 때문에 체내 양성자 빔의 분포를 확인하고 빔을 조정하면서 치료할 수 있는 적절한 방법이 없다. 양성자 빔의 물질에 대한 흡수선량 분포와 물질과 양성자의 핵반응으로 방출되는 즉발 감마선의 상관관계를 이용한 측정시스템을 몬테칼로 전산코드로 전산모사하고 계산한 결과 체내 양성자 빔의 위치를 실시간으로 측정할 수 있음을 확인하였다.