• 대한금속재료학회지
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• 제48권12호
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• pp.1047-1055
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• 2010

The objective of this study is to investigate the ballistic properties of Zr-based amorphous alloy surface composites fabricated by high-energy electron-beam irradiation. The mixture of Zr-based amorphous powders and $LiF+MgF_2$ flux powders was deposited on a pure Ti substrate, and then an electron beam irradiated this powder mixture to fabricate a one-layer surface composite. A four-layer surface composite, in which the composite layer thickness was larger than 3 mm, was also fabricated by irradiating the deposited powder mixture by an electron beam three times on the one-layer surface composite. The microstructural analysis results indicated that a small amount of fine crystalline particles were homogeneously distributed in the amorphous matrix of the surface composite layer. According to the ballistic impact test results, the surface composite layers effectively blocked a fast traveling projectile, while many cracks were formed at the composite layers, and thus the surface composite plates were not perforated. The surface composite layer containing ductile ${\beta}$ dendritic phases showed a better ballistic performance than the one without dendrites because dendritic phases hindered the propagation of shear bands or cracks.

• Journal of Korean Vacuum Science & Technology
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• 제3권1호
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• pp.59-65
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• 1999

There has been an interest to develop an efficient, compact microwave device using field-emitter-arrays (FEA)-based cathode. Toe valuate the optimum device-efficiency in a compact size, the propagation properties of the premodulated electron beam for the FEA-based cathode is studied in detail by the computer simulation using a PIC code, MAGIC. For the premodulated electron beam whose phase of the energy leads the phase of the current by $\pi$/2, the amplitude of the downstream current modulation can be kept as high as the initial modulation level. Using the beam parameters with the beam voltage of 6kV and the current of 2.0A, 30% of efficiency is predicted when the quality factor of 800 is chosen. the device length is reduced about twice compared with that of the conventional device. The design of practical planar cathode is carried out to meet the minimum diameter of the electron beam as 0.5 mm.

• 한국초전도ㆍ저온공학회논문지
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• 제18권4호
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• pp.15-20
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• 2016

The effects of electron beam (EB) irradiation on the superconducting critical temperature ($T_c$) and critical current density ($J_c$) of YBCO films were studied. The YBCO thin films were irradiated using a KAERI EB accelerator with an energy of 0.2 MeV and a dose of $10^{15}-10^{16}e/cm^2$. A small $T_c$ decrease and a broad superconducting transition were observed as the EB dose increased. The value of $J_cs$ (at 20 K, 50 K and 70 K) increased at doses of $7.5{\times}10^{15}$ and $2.2{\times}10^{16}e/cm^2$. However, $J_cs$ decreased as the dose increased further. The X-ray diffraction (XRD) analysis showed that the c axis of YBCO was elongated and the full width at half maximum (FWHM) increased as the dose increased, which is strong evidence of the atomic displacement by EB irradiation. The transmission electron microscopy (TEM) showed that the amorphous layer formed in the vicinity of the surfaces of the irradiated films. The amorphous phase was often present as an isolated form in the interior of the films. In addition to the formation of the amorphous phase, many striations running along the a-b direction of YBCO were observed. The high magnification lattice image showed that the striations were stacking faults. The enhancement of $J_c$ by EB irradiation is likely to be due to the lattice distortion and the formation of defects such as vacancies and stacking faults. The decrease in $J_c$ at a high EB dose is attributed to the extension of the amorphous region of a non-superconducting phase.

• 방사선산업학회지
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• 제8권2호
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• pp.71-76
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• 2014

Endocrine disrupting chemicals (EDCs) and potential EDCs are mostly man-made, found in various materials such as pesticides, additives or contaminants in food, and personal care products. The high energy ionizing radiation has the ability to remove the EDCs with a very high degree of reliability and in a clean and efficient manner. The ionizing radiation interacts with EDCs both directly and indirectly. Direct interaction takes place with EDCs and the structure of EDCs is destroyed or changed. During indirect interaction, radiolysis products of water result in the formation of highly reactive intermediates which then react with the target molecules, culminating in structural changes. To confirm the radiation reduction of EDCs in industrial sludge, a pilot scale experiment up to 50 kGy of electron beam (EB) was conducted with samples from the textile dyeing industries. The experimental result showed the over 90% of reduction of Nonylphenol (NP) and Di(2-ethylhexyl) phthalate (DEHP) at around 10 kGy of absorbed doses.

• 방사선산업학회지
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• 제4권3호
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• pp.265-269
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• 2010

Silicon-based non-oxide ceramic carbide fiber is one of the leading candidate ceramic materials for engineering applications because of its excellent mechanical properties at high temperature and good chemical resistance. In this study, polycarbosilane(PCS) and zirconium butoxide were used as a precursor to prepare polyzirconocarbosilane (PZC) fibers. A polymer solution was prepared by dissolving PCS in zirconium butoxide (50/50 wt%). This solution was heated at $250^{\circ}C$ in a nitrogen atmosphere for 2 hour with stirring, and then dried in a vacuum oven for 48 hour. PZC fibers were fabricated using an electrospinning technique. The fibers were irradiated with an electron beam to induce structural crosslinking. Crosslinked PZC fibers were heat treated at $1,300^{\circ}C$ in a nitrogen atmosphere. The microstructures of PZC fibers were examined by SEM. Chemical structures of PZC fibers were examined by FT-IR and XRD. Thermal stability of PZC fibers was investigated by TGA.

• 한국의학물리학회지:의학물리
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• 제31권2호
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• pp.9-19
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• 2020

Purpose: This study aims to develop a multi-purpose electron beam irradiation device for preclinical research and material testing using the research electron linear accelerator installed at the Dongnam Institute of Radiological and Medical Sciences. Methods: The fabricated irradiation device comprises a dual scattering foil and collimator. The correct scattering foil thickness, in terms of the energy loss and beam profile uniformity, was determined using Monte Carlo calculations. The ion-chamber and radiochromic films were used to determine the reference dose-rate (Gy/s) and beam profiles as functions of the source to surface distance (SSD) and pulse frequency. Results: The dose-rates for the electron beams were evaluated for the range from 59.16 Gy/s to 5.22 cGy/s at SSDs of 40-120 cm, by controlling the pulse frequency. Furthermore, uniform dose distributions in the electron fields were achieved up to approximately 10 cm in diameter. An empirical formula for the systematic dose-rate calculation for the irradiation system was established using the measured data. Conclusions: A wide dose-rate range electron beam irradiation device was successfully developed in this study. The pre-clinical studies relating to FLASH radiotherapy to the conventional level were made available. Additionally, material studies were made available using a quantified irradiation system. Future studies are required to improve the energy, dose-rate, and field uniformity of the irradiation system.

• 대한전자공학회논문지SD
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• 제45권3호
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• pp.1-5
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• 2008

본 논문은 고에너지 전자빔을 이용하여 저궤도 인공위성의 실리콘 태양센서의 내방사선 특성 변화를 분석하였다. 일반적으로 저궤도를 선회하는 위성은 반알렌대를 통과하며, 이 안에서 주기적인 운동으로 남극과 북극을 이동하는 하전입자에 의해 전자부품이 쉽게 손상되고 수명이 단축되는 등 악 영향을 받고 있다. 특히 방사선에 의한 SEU (Single Event Upset) 등은 인공위성에 탑재된 반도체 소자의 오동작 유발의 원인이 되고 있다. 본 논문은 한국원자력 연구원의 고에너지 ($300keV{\sim}1MeV$) 전자빔 조사장치를 이용하여 태양전지에 전자빔을 조사하고 이 때 변화되는 각각의 파라미터들에 대한 값을 측정하고자 한다. 이러한 연구는 저궤도 인공위성에서 전력을 생산하기 위해서 사용하는 전력용 태양 전지의 방사능 영향을 이해하는 데도 많은 영향을 줄 수 있을 것으로 기대된다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 춘계학술대회 논문집
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• pp.39-39
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• 2010

낮은 에너지를 이용하여 상대론적 영역에서 동작하는 마이크로파 출력장치를 연구하였다 그에 따른 후진파 발진기는 대전력 마이크로파를 발생시키는 장치로서 연구하였으며 관내에 전자빔을 입사시킴으로서 발진이 일어나 출력을 발생 시킨다.

• 한국진공학회지
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• 제15권3호
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• pp.325-330
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• 2006

ITER (International Thermonuclear Experimental Reactor) 조달용 일차벽의 제조 건전성을 검증하기 위해서, 일차벽을 구성하는 Cu/SS mock-up을 제작하여 고열부하 시험을 수행하였다. Cu/SS mock-up은 CuCrZr과 SS316L이 사용되었으며, 두 금속은 $1050^{\circ}C$, 150 MPa의 조건에서 고온등방가압법 (HIP, Hot Isostatic Pressing) 과정을 통해 접합되었다. 시험에 사용된 고열부하 장치는 일본 원자력연구소의 JEBIS (JAEA Electron Beam Irradiation Stand)를 이용하였으며, 시험 조건은 FEM 코드인 ANSYS 해석을 통해 결정하였다. 시험은 $5MW/m^2$의 고열부하를 15초간 인가하고, 30초간 냉각하는 방법으로 수행되었으며, 시험 종료 후 얻어진 시험결과와 해석결과가 잘 일치함을 확인하였다.

• 한국진공학회지
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• 제12권4호
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• pp.228-234
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• 2003

전자빔으로 증발시킨 gadolinium(Gd) 원자증기의 속도를 미량 저울(microbalance)을 사용하여 측정하였다. 증발 표면의 온도가 2400-2500 K인 조건에서 약 900 ㎧의 속도가 측정되었다. 이 값은 단열팽창을 하는 이상적 단원자의 최대 속도에 비해 약 100 ㎧ 더 빠른 속도에 해당된다. 이 특이 현상의 원인을 고온에서 여러 개의 들뜬 에너지 준위에 분포한 Gd 원자의 내부 에너지가 단열팽창 중에 운동 에너지로 전환되는 것으로 설명하였다. 100개의 들뜬 에너지 준위를 원자증기의 엔탈피에 포함시켜 속도를 계산한 값이 실험 결과와 비교적 일치함을 보였다. 가열된 표면 온도의 변화에 따른 원자증기의 유동 특성에 대해서도 보고한다.