• Nuclear Engineering and Technology
• /
• v.55 no.3
• /
• pp.1084-1096
• /
• 2023

On-the-fly(OTF) generation of Spectral Superhomogenization(SSPH) factors is analyzed in the multigroup(MG) whole core calculation employing pin-wise continuous energy(CE) slowing-down solutions. The motivation for the work is to avoid the huge computing time required for the generation of a parametrized SSPH factor library(PSSL) which is used to resolve the angular dependency of MG resonance cross sections, and also to exploit the advantage of flexible choice of a MG structure by using CE slowing-down solutions. Two pin-wise CE slowing-down methods, the equivalent Dancoff cell method and the shadowing effect correction method, are evaluated with the OTF SSPH method. The effectiveness of the OTF SSPH method is examined for various simplified and realistic core problems with various MG structures. It is demonstrated that the computing time overhead of this method is negligible whereas the solution accuracy is considerably enhanced.

• Journal of Radiation Protection and Research
• /
• v.10 no.2
• /
• pp.89-95
• /
• 1985

An alternative estimator for dose equivalent was derived. The original LET distribution concept was transformed into a charged particle fluence spectrum concept along with the definition of an average quality factor named slowing-down averaged quality factor by adopting the continuous slowing down approximation. With the alternative estimator, the dose equivalent delivered into a receptor located in a given radiation field can be directly and conveniently estimated in a Monte Carlo procedure. The slowing-down averaged quality factors for the energy range below 10 MeV were evaluated and tabulated for the charged particles which may be generated from the interactions of neutron with the nuclei composing soft tissue.

• Nuclear Engineering and Technology
• /
• v.49 no.6
• /
• pp.1199-1210
• /
• 2017

A new in-line method for sampling neutrons emitted in (${\alpha}$,n) reactions based on alpha particle source information has been developed for continuous-energy Monte Carlo simulations. The new method uses a continuous-slowing-down model coupled with (${\alpha}$,n) cross section data to precompute the expected neutron yield over the alpha particle lifetime. This eliminates the complexity and computational cost associated with explicit charged particle transport. When combined with an integrated alpha particle decay source sampling capability, the proposed method provides an efficient and accurate method for sampling (${\alpha}$,n) neutrons based solely on nuclide inventories in the problem, with no additional user input required. Results from several example calculations show that the proposed method reproduces the (${\alpha}$,n) neutron yields and energy spectra from reference experiments and calculations.

• Journal of Radiation Protection and Research
• /
• v.18 no.2
• /
• pp.17-25
• /
• 1993

Beta ray spectra of $^3H,\;^{14}C\;and\;^{36}Cl$ in liquid scintillation counting system have been calculated using the Monte Carlo method by which physical behaviors of particle transport in medium were simulated. The calculations have been carried out on the basis of beta rays being slowing down according to the continuous slowing down approximation(CSDA) model. Beta rays generated in simulation geometry were traced until they lost their energy below 0.3keV that in known to be the detection limit in the liquid scintillation counter. Scintillator solution in which pure beta emitting radionuclides were dissolved uniformly was assumed to be bottled in the shape of right circular cylinder with 12.5mm in radius and 35mm in height. The comparison of the calculated and measured results showed satisfactory agreement between those two, with slight discrepancy due to self quenching in the case of lower energy of emitted beta particles in the solution.

• Nuclear Engineering and Technology
• /
• v.49 no.3
• /
• pp.549-555
• /
• 2017

A lead slowing-down spectrometer (LSDS) system is under development to analyze isotopic fissile content that is applicable to spent fuel and recycled material. The source neutron mechanism for efficient and effective generation was also determined. The source neutron interacts with a lead medium and produces continuous neutron energy, and this energy generates dominant fission at each fissile, below the unresolved resonance region. From the relationship between the induced fissile fission and the fast fission neutron detection, a mathematical assay model for an isotopic fissile material was set up. The assay model can be expanded for all fissile materials. The correction factor for self-shielding was defined in the fuel assay area. The corrected fission signature provides well-defined fission properties with an increase in the fissile content. The assay procedure was also established. The assay energy range is very important to take into account the prominent fission structure of each fissile material. Fission detection occurred according to the change of the Pu239 weight percent (wt%), but the content of U235 and Pu241 was fixed at 1 wt%. The assay result was obtained with 2~3% uncertainty for Pu239, depending on the amount of Pu239 in the fuel. The results show that LSDS is a very powerful technique to assay the isotopic fissile content in spent fuel and recycled materials for the reuse of fissile materials. Additionally, a LSDS is applicable during the optimum design of spent fuel storage facilities and their management. The isotopic fissile content assay will increase the transparency and credibility of spent fuel storage.

• Nuclear Engineering and Technology
• /
• v.2 no.4
• /
• pp.249-254
• /
• 1970

A time-energy transient characteristics of pulsed neutron transport problem with an inelastic kernel in the fast domain is solved exactly with a continuous energy transfer operator. A discrete time eigenvalue is found which is asymptotically dominant. The complete solution consists of three parts: a time-energy separable mode which is asymptotically dominant and a non-separable mode which is made up by two parts； a pure energy slowing-down transient and a mixture of time and energy transient which is negligible asymptotically.

• Progress in Medical Physics
• /
• v.20 no.4
• /
• pp.225-234
• /
• 2009

Geant4 (GEometry ANd Tracking) provides various packages specialized in modeling electromagnetic interactions. The validation of Geant4 physics models is a significant issue for the applications of Geant4 based simulation in medical physics. The purpose of this study is to evaluate accuracy of Geant4 electromagnetic physics for proton therapy. The validation was performed both the Continuous slowing down approximation (CSDA) range and the stopping power. In each test, the reliability of the electromagnetic models in a selected group of materials was evaluated such as water, bone, adipose tissue and various atomic elements. Results of Geant4 simulation were compared with the National Institute of Standards and Technology (NIST) reference data. As results of comparison about water, bone and adipose tissue, average percent difference of CSDA range were presented 1.0%, 1.4% and 1.4%, respectively. Average percent difference of stopping power were presented 0.7%, 1.0% and 1.3%, respectively. The data were analyzed through the kolmogorov-smirnov Goodness-of-Fit statistical analysis test. All the results from electromagnetic models showed a good agreement with the reference data, where all the corresponding p-values are higher than the confidence level $\alpha=0.05$ set.

• Journal of The Korea Institute of Healthcare Architecture
• /
• v.17 no.4
• /
• pp.7-14
• /
• 2011

This paper is intended to suggest some reference materials for future elderly housing design, especially smart home, in Korea, by reviewing the elements and applications of smart home concept for older adults in USA. Research method includes collecting materials by attending the regular SmartHome$^{(R)}$ part meeting, the navigation of related homepages, and the analysis of collected materials. Current researches in Korea look initial stage and show some general principles without practical concept & technologies of elderly facilities. SeniorSmart$^{(R)}$ Center in USA started on August 2007 with the 3 parts of SmartHOME$^{(R)}$, SmartWHEELS$^{(R)}$ and SmartBRAIN$^{(R)}$. The Center has been doing various multidisciplinary research projects but slowing down the planned processes due to national economic recession. The major researches of SmartHome$^{(R)}$ part can be summarized as follows; CS-PFP( Continuous Scale Physical Function Performance) laboratory is being in operation to help older adults and families make the difficult decision regarding the ability and safety to live independently. Three levels of necessary laboratories from uninhabited space to senior living environment were accommodated for field research. As core technologies of SmartHome$^{(R)}$, predicting & warning system of fall risk on recognizing gait signature patterns to identify any deviation from the normal patterns of the older adults, home monitoring system which will send alerts to a specified relative and/or health care professional when vital signs of the older adults will not be within normal parameters, and Mobility & Research Clinic for evaluating, treating the older adults & multidisciplinary research are under development. SmartHome$^{(R)}$ has made collaborative research agreements for field laboratory with various retirement communities and also is continuing to work for experimental software engineering with the Fraunhofer Institute, Germany.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.17 no.1
• /
• pp.89-99
• /
• 2018

The number of traffic accidents in Korea has been increasing since 2014. In most school zones, safety signs are installed to prevent children's traffic accidents. However, it has been known that the effects of those signs are not significant. A variable message sign(VMS), one of the components of Intelligent Transport System(ITS), has emerged as an alternative method. Therefore, this study examines relative effects of two different VMS messages(Timely vs. Continuous) on vehicle speed. Experiments were conducted in two school zones. 6,676 vehicles were measured for speed limit compliance. A counterbalanced multiple baseline design was adopted. The results showed that both types of message are effective in reducing the speed of vehicle. Specifically, A timely message was more effective in slowing down vehicle speed and improving speed limit compliance than a continuous message. The present study suggested that a VMS with human factors can be effective.