EXPERIMENTAL ANALYSES OF SPALLATION NEUTRONS GENERATED BY 100 MEV PROTONS AT THE KYOTO UNIVERSITY CRITICAL ASSEMBLY

Pyeon, Cheol Ho,Azuma, Tetsushi,Takemoto, Yuki,Yagi, Takahiro,Misawa, Tsuyoshi Korean Nuclear Society 2013 Nuclear Engineering and Technology Vol.45 No.1

Neutron spectrum analyses of spallation neutrons are conducted in the accelerator-driven system (ADS) facility at the Kyoto University Critical Assembly (KUCA). High-energy protons (100 MeV) obtained from the fixed field alternating gradient accelerator are injected onto a tungsten target, whereby the spallation neutrons are generated. For neutronic characteristics of spallation neutrons, the reaction rates and the continuous energy distribution of spallation neutrons are measured by the foil activation method and by an organic liquid scintillator, respectively. Numerical calculations are executed by MCNPX with JENDL/HE-2007 and ENDF/B-VI libraries to evaluate the reaction rates of activation foils (bismuth and indium) set at the target and the continuous energy distribution of spallation neutrons set in front of the target. For the reaction rates by the foil activation method, the C/E values between the experiments and the calculations are found around a relative difference of 10%, except for some reactions. For continuous energy distribution by the organic liquid scintillator, the spallation neutrons are observed up to 45 MeV. From these results, the neutron spectrum information on the spallation neutrons generated at the target are attained successfully in injecting 100 MeV protons onto the tungsten target.

Benchmarks of subcriticality in accelerator-driven system at Kyoto University Critical Assembly

Cheol Ho Pyeon,Masao Yamanaka,김송현,Thanh-Mai Vu,TOMOHIRO ENDO,Willem Fredrik G. Van Rooijen,GO CHIBA 한국원자력학회 2017 Nuclear Engineering and Technology Vol.49 No.6

Basic research on the accelerator-driven system is conducted by combining 235U-fueled and 232Th-loaded cores in the Kyoto University Critical Assembly with the pulsed neutron generator (14 MeV neutrons) and the proton beam accelerator (100 MeV protons with a heavy metal target). The results of experimental subcriticality are presented with a wide range of subcriticality level between near critical and 10,000 pcm, as obtained by the pulsed neutron source method, the Feynman-α method, and the neutron source multiplication method.

Low-temperature wafer-scale synthesis of two-dimensional SnS₂

Pyeon, Jung Joon,Baek, In-Hwan,Lim, Weon Cheol,Chae, Keun Hwa,Han, Seong Ho,Lee, Ga Yeon,Baek, Seung-Hyub,Kim, Jin-Sang,Choi, Ji-Won,Chung, Taek-Mo,Han, Jeong Hwan,Kang, Chong-Yun,Kim, Seong Keun The Royal Society of Chemistry 2018 Nanoscale Vol.10 No.37

<P>Research on two-dimensional (2D) metal dichalcogenides is rapidly expanding owing to their unique characteristics that do not exist in bulk materials. The industrially compatible development of these emerging materials is indispensable to facilitate the transition of 2D metal dichalcogenides from the research stage to the practical industrial application stage. However, an industrially relevant method, <I>i.e.</I>, the low-temperature synthesis of wafer-scale, continuous, and orientation-controlled 2D metal dichalcogenides, still remains a significant challenge. Here, we report the low-temperature (≤350 °C) synthesis of uniform and continuous n-type SnS2 thin films <I>via</I> the combination of atomic layer deposition (ALD) of tin oxides and subsequent sulfurization. Well-crystallized and aligned SnS2 layers parallel to the substrate are demonstrated through the phase engineering of the ALD-grown tin oxide and the substrate surface. The additional H2S plasma treatment at 300 °C leads to the formation of stoichiometric SnS2. The formation of conformal SnS2 layers over a three-dimensional undulating hole structure is confirmed, which reveals the potential for applications beyond the planar structured architecture. The present results could be a step toward the realization of 2D metal dichalcogenides in industry.</P>

Sensitivity of a control rod worth estimate to neutron detector position by time-dependent Monte Carlo simulations of the rod drop experiment

박종민,Pyeon Cheol Ho,심형진 한국원자력학회 2024 Nuclear Engineering and Technology Vol.56 No.3

The control rod worth sensitivity to the neutron detector position in the rod drop experiment is studied by the time-dependent Monte Carlo (TDMC) neutron transport calculations for AGN-201K educational reactor and the Kyoto University Critical Assembly. The TDMC simulations of the rod drop experiments are conducted by the Seoul National University Monte Carlo (MC) code, McCARD, yielding time-dependent neutron densities at detector positions. The detector-position-dependent results of the total control rod worth calculated by the extrapolation, the integral counting, and the inverse methods are compared with the numerical reference using the MC eigenvalue calculations and the experimental results. From these comparisons, it is observed that the total control rod worth can be estimated with a considerable difference depending on the detector position through the rod drop experiment. The proposed TDMC simulation of the rod drop experiment can be applied for searching a better detector position or quantifying a bias for the control rod worth measurement.

Fiber-optic humidity sensor system for the monitoring and detection of coolant leakage in nuclear power plants

김혜진,신현영,Pyeon Cheol Ho,김신,이봉수 한국원자력학회 2020 Nuclear Engineering and Technology Vol.52 No.8

In this study, we developed a fiber-optic humidity sensor (FOHS) system for the monitoring and detection of coolant leakage in nuclear power plants. The FOHS system includes an FOHS, a spectrometer, a halogen white-light source, and a Y-coupler. The FOHS is composed of a humidity-sensing material, a metal tube, a multi-mode plastic optical fiber, and a subminiature version A (SMA) fiber-optic connector. The humidity-sensing material is synthesized from a mixture of polyvinylidene fluoride (PVDF) in dimethyl sulfoxide (DMSO) and hydroxyethyl cellulose (HEC) in distilled water. We measured the optical intensity of the light signals reflected from the FOHS placed inside the humidity chamber with relative humidity (RH) variation from 40 to 95%. We found that the optical intensity of the sensing probe increased linearly with the RH. The reversibility and reproducibility of the FOHS were also evaluated.

HTC 차상안테나 시험을 위한 시험용 취부대 연구

김진철(Jin-Cheol Kim),이훈구(Hoon-koo Lee),이수주(Soo-Joo Lee),박강훈(Kang-Hun Park),편선호(Seon-Ho Pyeon),김예지(Ye-Ji Kim) 한국철도학회 2014 한국철도학회 학술발표대회논문집 Vol.2014 No.5

하이브리드 궤도회로(Hybrid Track Circuit; HTC) 개발 연구의 목적은 열차제어를 위한 지상의 정보를 차상에 송수신 하기 위하여 특정한 주파수 대역에 응동하는 RFID(Radio Frequency Identification)기능이 내장된 각종 트랜스폰더의 기본 기능을 바탕으로 좀 더 단순하고 소형화된 제품을 개발을 통하여 혁신적인 비용절감을 목적으로 진행되고 있다. 따라서 본 연구에서는 지상장치 RFID용 태그(Tag)와 차상에 설치된 차상안테나를 설치함에 있어 인식률이 높은 차상안테나의 개발은 물론 구조형태가 각기 다른 열차들의 특성을 고려하여 열차의 공통표준이 되는 취부대를 개발하여 조립설치가 간단하고 테스트가 용이한 구조의 취부대 개발과 충격 및 진동과 같은 외부환경으로부터 견디어내고 완벽한 기능을 확보할 수 있는 실험용 취부대 설치방안을 제시하고자 한다. Hybrid track circuits (Hybrid Track Circuit; HTC) The purpose of the research and development of ground train control information to on-board for a specific frequency band in order to transmit and receive eungdong the RFID (Radio Frequency Identification) transponders with built-in the basic function of the various on the basis of a more simple and miniaturized through the development of innovative products for the purpose of cost reduction underway. In this study, the ground apparatus for RFID tag (Tag) is installed on -board and on-board antenna and a recognition rate is high as in the development of on-board antennas , as well as different structural forms that considering the characteristics of a train of a common standard are being taken bag train to develop and test a simple and easy assembly and installation of the structure and development take bags from the environment , such as shock and vibration stood out to secure a fully functional installation of experimental measures taken to suggest the bag

철도 승강장 선로의 침입자 및 장애물 검지시스템에 관한 연구

김유호(Kim You-Ho),김진철(Kim Jin-Cheol),최권희(Choi Kwon-Hee),편선호(Pyeon Seon-Ho),황종규(Hwang Jong-Gyu) 한국철도학회 2009 한국철도학회 학술발표대회논문집 Vol.2009 No.5월

Passenger safety is a primary concern of the railway system. However, dozens of people are killed every year when they accidently fall on to the track from the boarding platform. This is one of the most urgent issues to solve regarding the railway platform. The installation environment, and the blind area problems as well as maintenance and operating costs which are not efficient have to be looked at. To solve these problems, we propose a 3D laser radar sensor based monitoring system for the railway platform. This paper introduces an overview, the detecting method, and the interface with the signalling system in detecting a fallen passenger from the platform using the 3D laser radar sensor.

Feasibility study on fiber-optic inorganic scintillator array sensor system for multi-dimensional scanning of radioactive waste

박재형,송시원,김승현,김진홍,조승현,Pyeon Cheol Ho,이봉수 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.9

We developed a miniaturized multi-dimensional radiation sensor system consisting of an inorganic scintillator array and plastic optical fibers. This system can be applied to remotely obtain the radioactivity distribution and identify the radionuclides in radioactive waste by utilizing a scanning method. Variation in scintillation light was measured in two-dimensional regions of interest and then converted into radioactivity distribution images. Outliers present in the images were removed by using a digital filter to make the hot spot location more accurate and cubic interpolation was applied to make the images smoother and clearer. Next, gamma-ray spectroscopy was performed to identify the radionuclides, and three-dimensional volume scanning was also performed to effectively find the hot spot using the proposed array sensor.

NEW EVALUATION METHODS FOR RADIAL UNIFORMITY IN NEUTRON TRANSMUTATION DOPING

HAKSUNG KIM,JAE-YONG LIM,CHEOL HO PYEON,TSUYOSHI MISAWA,SEIJI SHIROYA,SANG-JUN PARK,MYONG-SEOP KIM,SOO-YOUL OH,BYUNG-JIN JUN 한국원자력학회 2010 Nuclear Engineering and Technology Vol.42 No.4

Recently, the neutron irradiation for large diameter silicon (Si)-ingots of more than 8" diameter is requested to satisfy the demand for the neutron transmutation doping silicon (NTD-Si). By increasing the Si-ingot diameter, the radial non-uniformity becomes larger due to the neutron attenuation effect, which results in a limit of the feasible diameter of the Si-ingot. The current evaluation method has a certain limit to precisely evaluate the radial uniformity of Si-ingot because the current evaluation method does not consider the effect of the Si-ingot diameter on the radial uniformity. The objective of this study is to propose a new evaluation method of radial uniformity by improving the conventional evaluation approach. To precisely predict the radial uniformity of a Si-ingot with large diameter, numerical verification is conducted through comparison with the measured data and introducing the new evaluation method. A new concept of a gradient is introduced as an alternative approach of radial uniformity evaluation instead of the radial resistivity gradient (RRG) interpretation. Using the new concept of gradient, the normalized reaction rate gradient (NRG) and the surface normalized reaction rate gradient (SNRG) are described. By introducing NRG, the radial uniformity can be evaluated with one certain standard regardless of the ingot diameter and irradiation condition. Furthermore, by introducing SNRG, the uniformity on the Si-ingot surface, which is ignored by RRG and NRG, can be evaluated successfully. Finally, the radial uniformity flattening methods are installed by the stainless steel thermal neutron filter and additional Si-pipe to reduce SNRG.

자연어 처리와 Diffusion 모델을 이용한 동화 장면 생성

김승주(Seung-ju Kim),정원철(Jeong-won cheol),박지호(Ji-ho Park),편수장(Soo-jang Pyeon),이동훈(Dong-Hoon Lee),고병철(Byoung Chul Ko) 대한전자공학회 2023 대한전자공학회 학술대회 Vol.2023 No.6

This paper proposes a system that uses a fine-tuned diffusion model to generate fairy tale images from text inputs for children. This system consists of three modules: a natural language processing module that converts mixed Korean and English texts into suitable prompts for the diffusion model, a text-to-image generation module that uses a pre-trained stable diffusion model with low-rank adaptation and negative prompts, and a mobile application that allows users to interact with the system through text inputs and displays the generated images. This paper evaluates the performance and usefulness of the system for text input and discusses the applications and limitations of the system.