Monte-Carlo Simulation of the Prompt Gamma Neutron Activation Analysis System with a Femtosecond Laser

심현하,홍병식,이경세,이성만,차형기 한국물리학회 2012 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.61 No.5

The prompt gamma neutron activation analysis (PGNAA) system is a useful tool to detect the concentrations of the various composite elements of a sample by measuring the prompt gammas that are activated by neutrons. The composition in terms of the constituent elements is essential information for the identification of the material species of any unknown object. A PGNAA system initiated by a high-power laser has been designed and optimized by using a Monte-Carlo simulation. In order to improve the signal-to-background ratio, we designed an improved neutron-shielding structure and imposed a proper time window in the analysis. In particular, the yield ratio of nitrogen to carbon in a TNT sample was investigated in detail. These simulation results demonstrate that the gamma rays from an explosive sample under a vast level of background can indeed be identified.

A Monte Carlo Simulation Study of a Therapeutic Proton Beam Delivery System Using the Geant4 Code

신정욱,심현하,곽정원,김동욱,박성용,조관호,이세병,Shin, Jungwook,Shim, Hyunha,Kwak, Jungwon,Kim, Dongwook,Park, Sungyong,Cho, Kwan Ho,Lee, Se Byeong Korean Society of Medical Physics 2007 의학물리 Vol.18 No.4

국립암센터에 설치된 양성자 치료기의 빔 전달 시스템에 대하여 Geant4 코드를 이용하여 몬테카를로 전산모사를 수행하였고, 선량검증 도구로써의 이용 가능성에 대하여 연구하였다. 몬테카를로 기술을 기반으로 하는 선량계산은 물질내의 선량분포를 이해하는 데 가장 정확한 방법으로 알려져 있다 외부조사 방사선치료에 있어서 이 방법의 장점을 극대화 하기 위해서는, 빔이 지나가는 곳에 놓여진 노즐 구성요소들의 정확한 모델링과 더불어 초기빔 특성파악은 무엇보다 중요하다. 국립암센터에 설치된 양성자 치료기는 총 3가지 형태-double/single scattering, uniform scanning and pencil-beam scanning-로 치료빔을 조사할 수 있으며, 본 연구진은 Geant4.8.2 코드를 기반으로 double/single scattering 모드를 구성하는 모든 노즐구성요소들에 대하여 모델링 하였다. 특정 치료감이에 대하여 실험치와 일치하는 전산모사의 결과를 얻었다 본 기관에 설치된 양성자치료기에 대한 몬테카를로 전산모사에 대한 기반을 성공적으로 구축하였고, 치료빔에 대하여 정밀한 선량측정에 이용할 수 있다. 치료빔의 전 에너지 영역에 걸쳐 추가적인 커미셔닝을 수행할 것이다. We studied a Monte Carlo simulation of the proton beam delivery system at the National Cancer Center (NCC) using the Geant4 Monte Carlo toolkit and tested its feasibility as a dose verification framework. The Monte Carlo technique for dose calculation methodology has been recognized as the most accurate way for understanding the dose distribution in given materials. In order to take advantage of this methodology for application to external-beam radiotherapy, a precise modeling of the nozzle elements along with the beam delivery path and correct initial beam characteristics are mandatory. Among three different treatment modes, double/single-scattering, uniform scanning and pencil beam scanning, we have modeled and simulated the double-scattering mode for the nozzle elements, including all components and varying the time and space with the Geant4.8.2 Monte Carlo code. We have obtained simulation data that showed an excellent correlation to the measured dose distributions at a specific treatment depth. We successfully set up the Monte Carlo simulation platform for the NCC proton therapy facility. It can be adapted to the precise dosimetry for therapeutic proton beam use at the NCC. Additional Monte Carlo work for the full proton beam energy range can be performed.

기후변화 영향에 의한 국내외 수도 이전 사례 연구

박정호,심현하,웃위린 한국재난정보학회 2016 한국재난정보학회 학술대회 Vol.2016 No.11

본 논문에서는 최근 가속화 되고 있는 기후변화에 따른 여러 영향에 의한 국내·외 수도 이전 사례를 역사를 바탕으로 과거의 기후변화와 현재의 기후변화를 차이점을 중심으로 비교했으며 한반도의 수도이전역사와 기후변화의 관계 그리고 기후변화가 현재수도 서울에 미치는 영향을 조사했으며 서울 의 기후변화 전망과 미래에 기후변화에 대비해야할 방안을 연구하였다.

도시재생 뉴딜정책과 연계한 지역맞춤 안전도시 활성화 정책

박정호,심현하,도기선,장주연,전찬기 한국재난정보학회 2017 한국재난정보학회 학술대회 Vol.2017 No.11

본 논문에서는 안전도시 정책에 관한 사례와 도시재생 정책 사례를 바탕으로 통합된 가이드라인을 통한 지역 맞춤 안전도시 정책을 통해 시민의 삶의 질 향상과 도시지속성을 유지할 방안을 연구하였다.

Design of Wide-energy-range Neutron Calorimeter for Nuclear Collisions in the Korea Rare-isotope Accelerator

홍병식,Genie Jhang,주은아,이경세,심현하 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.58 No.2

We have designed a neutron calorimeter dedicated to the measurement of the nuclear symmetry energy in the planned Korea rare-isotope accelerator. The design was optimized to precisely measure the neutron energy with high efficiency in a wide energy range from about 30 to 300 MeV. The final configuration of the detector is a hybrid of the homogeneous and the sampling calorimeters with a veto counter in the front. The homogeneous part is ideal for measuring low-energy neutrons below ∼50 MeV whereas the sampling part is efficient for measuring high-energy neutrons. The detection efficiency is estimated to be about 88% for neutron energies larger than 50 MeV and decreases to ∼78% at 30 MeV.We have estimated the energy resolution as a function of the incident energy based on the time-of-flight method. Assuming an ideal detector performance with null time resolution, the relative energy resolution decreases as the incident neutron energy increases. However, under a more realistic situation with a finite time resolution for the detector, the energy resolution monotonically increases with increasing the neutron energy, following a logarithmic function. Imposing an energy resolution of better than 3% at the highest neutron energy, we find the nominal position of the hybrid calorimeter to be 15 m from the target for a time resolution of 1.0 ns, but the detector needs to be free to move closer to or farther from the target, depending on the physics goal.

Scintillation-Fiber Detection for Dose Verification in Hadron Therapy

이경세,홍병식,Genie Jhang,주은아,김총,박성근,이한범,심현하,심광숙 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.58 No.4

In this paper, we report on the development of a scintillation-fiber detection method for dose verification in hadron therapy. In order to achieve the position sensitivity required for precision measurement of doses, a detector composed of 1-mm-thick scintillation fibers and a multi-channel photodiode was constructed and tested with 45-MeV proton beams provided by the MC50 proton cyclotron at the Korea Institute of Radiological and Medical Science (KIRAMS). The results of the beam test showed that the spatial resolution of the data determined by using the standard deviation σ was ∼1.0 mm, which is sufficiently accurate to verify beam-induced doses in hadron therapy. Furthermore, the quantitative accuracy appearing in the data is on the order of ∼1%. We expect the detector composed of scintillation fibers and operating in the charge-integration mode to allow us to perform quality measurement of doses in various hadron therapies.

Construction and Performance of a Prototype Multigap Resistive Plate Chamber

S.H.Ahn,홍병식,S.J.Hong,J.R.Ji,K.S.Lee,S.B.Lee,박성근,W.J.Park,M.S.Ryu,심현하,심광숙,J.K.Woo 한국물리학회 2002 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.40 No.2

We present the design, construction, and performance of a prototype multigap resistive plate chamber made of glass plates. A time resolution of 580 ps with a detection eciency above 95 % was achieved at the working high-voltage plateau with cosmic ray muons.ADDING-LEFT We present the design, construction, and performance of a prototype multigap resistive plate chamber made of glass plates. A time resolution of 580 ps with a detection efficiency above 95 % was achieved at the working high-voltage plateau with cosmic ray muons.

Operation of a RPC with Low Resistivity Bakelite for the Endcap Region of CMS in a High-Rate Environment

S.H.Ahn,E.J.Choi,홍병식,S.J.Hong,D.H.Kang,T.J.Kim,K.S.Lee,박성근,W.J.Park,M.S.Ryu,심현하,심광숙,S.W.Youn,김용주,Y.U.Kim,S.K.Nam,S.R.Jung,Y.L.Lee,J.T.Rhee,S.J.Lee,D.G.Koo,S.Y.Bahk 한국물리학회 2002 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.41 No.5

We present the beam-test results for a real-size prototype resistive plate chamber (RPC) for the endcap region of the Compact Muon Solenoid (CMS) experiment at CERN Large Hadron Collider (LHC). The chamber built with relatively low resistivity bakelite was tested at the Gamma Irradiation Facility (GIF) at CERN under a high photon-flux environment with an effective cluster rate up to about 1.2 kHz/cm2. The characteristics of the present chamber are compatible with the previous results for the muon detection effciency, time resolustion, mean travel time, and rate capability, which were obtained using a higher resistivity bakelite. The present beam-test results ensure that the RPC made of relatively low resistivity bakelite is also suitable for the CMS muon trigger detector. In addition, we study the position resolution of the endcap RPC of the CMS. By using the median position of the cluster strips, the position resolution can be reduced to only half of the strip width.