• 대한디지털의료영상학회논문지
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• 제12권1호
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• pp.65-69
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• 2010

High energy electron beams were to concentrically dose inside a tumor and more energy is a shape decreased of dose. Therefore, it is useful to radiation therapy of a tumor. Also high energy electron beams ionized into collision with a atom in structure material of tissue and it has big changes to dose distribution by multiple scattering. The study had to establish characteristic of electron beams from interaction of electron beams and materials. Experiment method was to measure dependence of electron beam central axis for depth dose curve, field flatness and symmetry and field size dependence. The results were able to evaluate data for a datum pint of electron beam. Also radiotherapy has to be considered for not only energy pencil of lines but characteristic, electron guide and isodose curves distribution.

• Applied Microscopy
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• 제45권4호
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• pp.236-241
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• 2015

Carbon-coated Ni, Cu and Sn nanocapsules were investigated by means of X-ray diffraction (XRD), transmission electron microscopy (TEM) and a four-point probe device. All of these nanocapsules were prepared by an arc-discharge method, in which the bulk metals were evaporated under methane ($CH_4$) atmosphere. Three pure metals (Ni, Cu, Sn) were typically diverse in formation of the carbon encapsulated nanoparticles and their different mechanisms were investigated. It was indicated that a thick carbon layers formed on the surface of Ni(C) nanocapsules, whereas a thin shell of carbon with 1~2 layers covered on Cu(C) nanocapsules, and the Sn(C) nanocapsules was, in fact, a longger multi-walled carbon nanotubes partially-filled with metal Sn. As one typical magnetic/dielectric nanocomposite particles, Ni(C) nanocapsules and its counterpart of oxide-coated Ni(O) nanocapsules were compared in the electrically conductive behaviors for further applications as the electromagnetic materials.

• Nuclear Engineering and Technology
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• 제55권9호
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• pp.3417-3422
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• 2023

Recently, as the clinically positive biological effects of ultra-high dose rate (UHDR) radiation beams have been revealed, interest in flash radiation therapy has increased. Generally, FLASH preclinical experiments are performed using UHDR electron beams generated by linear accelerators. Real-time monitoring of UHDR beams is required to deliver the correct dose to a sample. However, it is difficult to use typical transmission-type ionization chambers for primary beam monitoring because there is no suitable electrometer capable of reading high pulsed currents, and collection efficiency is drastically reduced in pulsed radiation beams with ultra-high doses. In this study, a monitoring method using bremsstrahlung photons generated by irradiation devices and a water phantom was proposed. Charges collected in an ionization chamber located at the back of a water phantom were analyzed using the bremsstrahlung tail on electron depth dose curves obtained using radiochromic films. The dose conversion factor for converting a monitored charge into a delivered dose was determined analytically for the Advanced Markus® chamber and compared with experimentally determined values. It is anticipated that the method proposed in this study can be useful for monitoring sample doses in UHDR electron beam irradiation.

• 한국의학물리학회지:의학물리
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• 제31권4호
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• pp.145-152
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• 2020

Purpose: In ionization-chamber dosimetry for high-dose-rate electron beams-above 20 mGy/pulse-the ion-recombination correction methods recommended by the International Atomic Energy Agency (IAEA) and the American Association of Physicists in Medicine (AAPM) are not appropriate, because they overestimate the correction factor. In this study, we suggest a practical ion-recombination correction method, based on Boag's improved model, and apply it to reference dosimetry for electron beams of about 100 mGy/pulse generated from an electron linear accelerator (LINAC). Methods: This study employed a theoretical model of the ion-collection efficiency developed by Boag and physical parameters used by Laitano et al. We recalculated the ion-recombination correction factors using two-voltage analysis and obtained an empirical fitting formula to represent the results. Next, we compared the calculated correction factors with published results for the same calculation conditions. Additionally, we performed dosimetry for electron beams from a 6 MeV electron LINAC using an Advanced Markus^® ionization chamber to determine the reference dose in water at the source-to-surface distance (SSD)=100 cm, using the correction factors obtained in this study. Results: The values of the correction factors obtained in this work are in good agreement with the published data. The measured dose-per-pulse for electron beams at the depth of maximum dose for SSD=100 cm was 115 mGy/pulse, with a standard uncertainty of 2.4%. In contrast, the k_s values determined using the IAEA and AAPM methods are, respectively, 8.9% and 8.2% higher than our results. Conclusions: The new method based on Boag's improved model provides a practical method of determining the ion-recombination correction factors for high dose-per-pulse radiation beams up to about 120 mGy/pulse. This method can be applied to electron beams with even higher dose-per-pulse, subject to independent verification.

• Journal of Korean Vacuum Science & Technology
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• 제6권2호
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• pp.101-104
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• 2002

Er doped SiOx films have been synthesized by ion beam assisted deposition (IBAD). The morphology and microstructure of films and their annealing behaviors have been examined by using scanning electron microscopy and x-ray diffraction. The composition and properties of films have been systematically investigated.

• 전자공학회논문지D
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• 제35D권9호
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• pp.26-34
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• 1998

본 논문은 주사전자현미경(SEM)의 전자총을 이용하여 MCM 또는 PCB 회로기판의 신호연결선에서 전압차를 유도시켜 개방/단락 등의 결함을 측정 검사하는 방법을 제시한다. 본 실험에서는 주사전자현미경의 구조를 변형시키지 알고 회로기판의 개방/단락 검사를 실시할 수 있는 이중전위전자빔(Dual Potential) 검사방법을 사용한다. 이중전위전자빔(Dual Potential) 측정검사 방법은 이차전자수율 값 δ의 차이를 유기시키는 δ < 1 인 충전 전자빔과 δ > 1 인 읽기 전자빔을 사용하여 한 개의 전자총이 각각 다른 가속전압에 의해 생성된 두 개의 전자빔으로 측정하는 방법으로 특정 회로네트에 대한 개방/단락 등의 측정 검사가 가능하다. 또한 읽기 전자빔을 이용할 경우 검사한 회로 네트를 방전시킬 수 있어 기판 도체에 유기된 전압차를 없앨 수 있는 방전시험도 실시할 수 있어, 많은 수의 회로네트를 지닌 회로 기판에 대해 측정 검사할 때 충전되어 있는 회로네트에 대한 측정오류를 줄일 수 있다. 측정검사를 실시한 결과 glass-epoxy 회로기판 위에 실장된 구리(Cu) 신호연결선은 7KeV의 충전 전자빔으로 충전시키고 10초 이내에 주사전자현미경을 읽기 모드로 바꾸어 2KeV의 읽기 전자빔으로 구리표면에서의 명암 밝기 차이를 읽어 개방/단락 상태를 검사할 수 있었다. 또한 IC 칩의 Au 패드와 BGA의 Au 도금된 Cu 회로패드를 검사한 결과도 7KeV 충전 전자빔과 2KeV 읽기 전자빔으로 IC칩 내부회로에서의 개방 단락 상태를 쉽게 검사할 수 있었다. 이 검사방법은 주사전자현미경에 있는 한 개의 전자총으로 비파괴적으로 회로 기판의 신호 연결선의 개방/단락 상태를 측정 검사할 수 있음을 보여 주었다.

• 원예과학기술지
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• 제34권1호
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• pp.122-133
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• 2016

While ion beams are widely used in plant breeding, little is known about the sensitivity of Lavandula angustifolia (lavender) to ionizing radiation. To compare the biological effects of different types of ionizing radiation on the germination and survival rates of lavender, we exposed lavender seeds to gamma rays, 3 MeV electron beams, and 1.89 MeV proton ion beams. We observed that the seed germination rate decreased with increasing dosages of all three types of ionizing radiation. The malformation rate of lavender seedlings exposed to electron beams and gamma rays increased with increasing radiation dosage. By contrast, the effect of the accelerated proton beams on the malformation rate was negatively correlated with the dosage used. The survival rate of lavender seedlings exposed to the three types of ionizing radiation decreased in a dose-dependent manner. In addition, the survival rate of seedlings irradiated with proton and electron beams decreased more slowly than did that of seedlings irradiated with gamma rays. The half-lethal dose of gamma rays, electron beams, and proton beams was determined to be 48.1 Gy, 134.3 Gy, and 277.8 Gy, respectively, and the most suitable proton-ion energy for lavender seeds in terms of penetration depth was determined to be 5 MeV. These findings provide valuable information for the breeding of lavender by radiation mutation.

• 한국의학물리학회지:의학물리
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• 제15권1호
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• pp.39-44
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• 2004

본 연구에서는 깊이선량률의 측정값과 단일에너지 계산값들로부터 치료용 전자선에 대한 에너지분포를 계산하였다. 최소제곱법에 기초한 수치연산을 이용하여 측정과 환산 깊이선량률의 차이가 최소가 되는 에너지분포를 결정하였다. 본 방법은 임상에 이용되는 명목에너지 6, 9, 12, 그리고 15 MeV 전자선에 대하여 적용되었다. 본 연구에서는 측정값과의 비교를 위하여 결정된 에너지분포를 입력자료로 이용한 깊이선량률의 몬테칼로 계산을 수행하였다. 계산된 깊이선량률을 측정값과 비교할 때, 모든 전자선에 대하여 표면에서 R$_{80}$ 깊이까지 측정값과 $\pm$3% 미만, 비정 근처까지 $\pm$4% 미만의 상대오차를 보였다. 본 연구는 입사 전자선의 에너지분포를 결정하기 위한 실용적 방법으로 응용될 수 있다.

• 한국의학물리학회지:의학물리
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• 제31권4호
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• pp.163-171
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• 2020

Purpose: In this study, the accuracies of electron Monte Carlo (eMC) calculation algorithms were evaluated to determine whether electron beams were modeled by optional air profiles (APs) designed for each applicator size. Methods: Electron beams with the energies of 6, 9, 12, and 16 MeV for VitalBeam (Varian Medical System, Palo Alto, CA, USA) and 6, 9, 12, 16, and 20 MeV for Clinac iX (Varian Medical System) were used. Optional APs were measured at the source-to-detector distance of 95 cm with jaw openings appropriate for each machine, electron beam energy, and applicator size. The measured optional APs were postprocessed and converted into the w2CAD format. Then, the electron beams were modeled and calculated with and without optional APs. Measured profiles, percentage depth doses, penumbras with respect to each machine, and energy were compared to calculated dose distributions. Results: For VitalBeam, the profile differences between the measurement and calculation were reduced by 0.35%, 0.15%, 0.14%, and 0.38% at 6, 9, 12, and 16 MeV, respectively, when the beams were modeled with APs. For Clinac iX, the differences were decreased by 0.16%, -0.31%, 0.94%, 0.42%, and 0.74%, at 6, 9, 12, 16, and 20 MeV, respectively, with the insertion of APs. Of note, no significant improvements in penumbra and percentage depth dose were observed, although the beam models were configured with APs. Conclusions: The accuracy of the eMC calculation can be improved in profiles when electron beams are modeled with optional APs.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.564-567
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• 2004

In the manufacture of integrated circuits, photolithography is the lowest yield step in present production lines. Electron beams form a powerful set of tools with which to attack this problem. Electron beams can be used to make patterns that are smaller than can a photolithography. We design a high voltage generator of electron beam manufacturing system. For this purpose, first, the configuration of electron beam manufacturing system was analyzed. Second, the basic configuration of a high voltage generator and test results were presented.