• Bulletin of the Korean Chemical Society
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• 제30권5호
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• pp.1067-1070
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• 2009

We studied change in water contact angle on $TiO_2$ surfaces upon high-energy electron-beam treatment. Depending on conditions of e-beam exposures, surface OH-content could be increased or decreased. In contrast, water contact angle continuously decreased with increasing e-beam exposure and energy, i.e. change in the water contact angle cannot be rationalized in terms of the overall change in the surfacestructure of carbon-contaminated $TiO_2$. In the C 1s spectra, we found that the C-O and C=O contents gradually increased with increasing e-beam energy, suggesting that the change in the surface structure of carbon layers can be important for understanding of the wettability change. Our results imply that the degree of oxidation of carbon impurity layers on oxide surfaces should be considered, in order to fully understand the change in the oxide surface wettability.

• Nuclear Engineering and Technology
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• 제49권8호
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• pp.1600-1609
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• 2017

The accelerator-driven subcritical system (ADS) is driven by a neutron source from spallation reactions introduced by the injected proton beam. Part of the neutron source has energy as high as a few hundred MeV to a few GeV. The effects of high-energy source neutrons ($E_n$ > 20 MeV) are usually approximated by energy cut-off treatment in practical core calculations, which can overestimate the predicted proton beam current in the ADS design. This article intends to quantize this effect and propose a way to solve this problem. To evaluate the effects of high-energy neutrons in the subcritical core, two models are established aiming to cover the features of current experimental facilities and industrial-scale ADS in the future. The results show that high-energy neutrons with $E_n$ > 20 MeV are of small fraction (2.6%) in the neutron source, but their contribution to the source efficiency is about 23% for the large scale ADS. Based on this, a neutron source efficiency correction factor is proposed. Tests show that the new correction method works well in the ADS calculation. This method can effectively improve the accuracy of the prediction of the proton beam current.

• 방사선산업학회지
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• 제5권1호
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• pp.41-46
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• 2011

Polyacrylonitrile (PAN) fibers are the most widely used precursor of the materials for carbon fibers. The conventional process of carbon fibers from PAN precursor fiber includes two step; stabilization at low temperature and carbonization at high temperature. Compared to thermal stabilization, the stabilization process by electron beam (E-beam) irradiation is a advanced and brief method. However, a stabilization by E-beam irradiation was required a high dose (over 5,000 kGy) and spend over 1.5 hr (1.14 MeV, 1 mA). In the present work the main goal is exploring a quick stabilization process by cotrolling E-beam currents. The effect of various E-beam currents on stabilization of PAN precursor fiber was studied by gel fraction test, thermo gravimertic analysis (TGA), differential scanning calorimetry (DSC), tensile strength, and scanning electron microscopy (SEM) images.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2004년도 하계종합학술대회 논문집(2)
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• pp.359-362
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• 2004

Electron beam on high energy acceleration, which travels deeply and sharply through photoresist, became to be used in e-beam lithography apparatus for nano-patterning in due to its high resolution. An advanced electron beam lithography simulation tool is currently undergoing development for nano-patterning. This paper will demonstrate such simulation efforts with experiments at 200 keV e-beam lithography processes on PMMA, ZEP520 of which photoresist parameters and characteristics will be explained with simulation results. Neureuther parameters was extracted from the contrast curve of the resist

• 한국광학회지
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• 제16권3호
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• pp.235-238
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• 2005

생산성 향상을 위하여 정렬된 마이크로칼럼을 이용하여 멀티-전자빔 리소그라피 장치를 개발하였다. 마이크로칼럼은 매우 작은 크기를 가지고 있어 병렬구조로 정렬하여 작동시킬 수 있다. Single Column Module(SCM) 구조의 멀티 전자빔 리소그라피 시스템과 전자칼럼을 제작하여 250 eV에서 300 eV 에너지 범위에서의 저에너지 마이크로칼럼 리소그라피를 성공적으로 수행하였다. 전자방출원에서 방출되는 전자빔의 총 전류가 $0.5\;{\mu}A$일 때, 샘플에서의 전류는 >1 nA으로 측정되었으며 리소그라피 패텅닝에서 사용된 working distance은 $\~1\;mm$였다.

• 한국정밀공학회지
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• 제33권1호
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• pp.45-51
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• 2016

The present study uses an electron beam (e-beam) to modify the wetting characteristics of thermoplastic polymer surfaces. A high energy e-beam irradiated various polymer surfaces (PET, PMMA, and PC), with variations in irradiation time and applied current. The water contact angles were measured on the e-beam irradiated surfaces in order to investigate the changes in the surface energy and the relevant wettability. Furthermore, XPS analyses were performed to investigate the chemical composition change in the e-beam irradiated surfaces; the results showed that the hydrophilic groups (C-O) increased after the electron beam irradiation. Also, water collection tests were performed for various polymer samples in order to investigate the effect of the surface energy on the ability of water collection, from which it can be seen that the irradiated surfaces revealed better water-collecting capability than pure polymer surfaces.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2012년도 추계학술대회 논문집
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• pp.125-126
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• 2012

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권2호
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• pp.1380-1383
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• 2007

The secondary electron emission coefficient (${\gamma}$) of the cathode is an important factor for improving the discharge characteristics of AC-PDP, because of its close relationship to discharge voltage. In this experiment, we have investigated the electronic structure of the energy band in the MgO layer responsible for the high ${\gamma}$. We used three kinds of MgO pellet that have another component, and each MgO layers have been deposited by electron beam evaporation method. The work-functions of MgO layer have been investigated from their ion-induced secondary electron emission coefficient (${\gamma}$), respectively, using various ions with different ionization energies in a ${\gamma}-FIB$ (Focused Ion Beam) system. We have compared work-function with ${\gamma}-FIB$ system current signal for measurement defect energy level in MgO layer. MgO-A in the three types has lowest work-function value (4.12eV) and there are two defect energy levels.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 추계학술대회 논문집
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• pp.329-330
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• 2007

Decay processes of accumulated charge in e-beam irradiated polymers during elevating temperature are observed using pulsed electro-acoustic measurement system. Since the polymeric materials have many superior properties such as light-weight, good mechanical strength, high flexibility and low cost, they are inevitable materials for spacecrafts. In space environment, however, the polymers sometimes have serious damage by irradiation of high energy charged particles. When the polymers of the spacecraft are irradiated by high energy charged particles, some of injected charges accumulate and remain for long time in the bulk of the polymers. Since the bulk charges sometimes cause the degradation or breakdown of the materials, the investigation of the charging and the decay processes in polymeric materials under change of temperature is important to decide an adequate material for the spacecrafts. By measuring the charge behavior in e-beam irradiated polymer, such as polyimide or polystyrene, it is found that the various accumulation and decay patterns are observed in each material. The results seem to be useful and be helpful to progress in the reliability of the polymers for the spacecraft.

• 전자공학회논문지
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• 제51권6호
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• pp.71-77
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• 2014

본 연구에서는 radio frequency(rf) 마그네트론 스퍼터링 기술을 이용하여 Corning 유리 기판에 증착된 InGaZnO (IGZO) 박막의 광 투과도 특성에 고 에너지 전자빔 조사(high-energy electron beam irradiation (HEEBI))이 미치는 영향을 연구하였다. 저온에서 증착된 IGZO 박막은 공기 중 과 상온 조건에서 0.8 MeV의 전자빔 에너지와 $1{\times}10^{14}-1{\times}10^{16}electrons/cm^2$ dose를 사용하여 HEEBI 처리 되었다. IGZO 박막의 광 투과도는 utraviolet visible near-infrared spectrophotometer (UVVIS)로 측정되었다. HEEBI 처리 된 IGZO/유리 이중층의 총 광 투과도에서 HEEBI 처리된 IGZO 단일막 만의 광 투과도를 분리하는 방법을 상세히 연구하였다. 실험 결과로부터 $1{\times}10^{14}electrons/cm^2$의 적절한 dose로 처리된 HEEBI가 IGZO 박막의 투명도를 극대화시킴을 알 수 있었다. 또한 이렇게 적절한 dose로 처리된 HEEBI가 광학 밴드갭($E_g$)을 3.38 eV에서 3.31 eV로 감소시킴을 알 수 있었다. 이러한 $E_g$의 감소는 적절한 dose로 공기 중 상온에서 처리된 HEEBI가 진공 중 고온에서 처리된 열적 annealing 효과와 유사함을 제시하고 있다.