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고 에너지 전자빔 조사에 따른 ZnO 기판의 결함생성 및 전기적 특성 변화
이동욱,송후영,한동석,김선필,김은규,이병철,Lee, Dong-Uk,Song, Hoo-Young,Han, Dong-Seok,Kim, Seon-Pil,Kim, Eun-Kyu,Lee, Byung-Cheol 한국진공학회 2010 Applied Science and Convergence Technology Vol.19 No.3
수열합성법(hydrothermal) 방식으로 성장한 ZnO 기판에 고에너지의 전자빔을 조사시킨 후 쇼트키(Schottky)다이오드를 제작하여 결함상태와 전기적 특성 변화를 조사하였다. 1 MeV 및 2 MeV 전자빔으로 $1{\times}10^{16}$ electrons/$cm^2$ dose로 기판의 Zn 면에 조사하였다. 1 MeV 전자빔이 조사된 시료에서는 표면에 전자빔 유도결함을 형성시켜 누설전류를 증가시켰고, 2 MeV 전자빔의 경우는 오히려 다이오드 누설절류 감소와 on/off 특성을 향상시키는 것으로 나타났다. 이들 시료에 대한 DLTS (deep level transient spectroscopy) 측정결과 전자빔 조사에 따른 전기적 물성변화는 활성화에너지와 포획단면적이 각각 $E_c$-0.33 eV 및 $2.97{\times}10^{15}\;cm^{-2}$인 O-vacancy가 주된 연관성을 보였으며, 활성화에너지 $E_v$+0.8 eV인 결함상태도 새롭게 완성되었다. The electrical properties and defect states in ZnO substrates were studied during high-energy electron beam irradiations. 1 MeV and 2 MeV electron-beam with dose of $1{\times}10^{16}$ electrons/$cm^2$ were irradiated on Zn-surface of the sample. In the sample irradiated by 1 MeV, the leakage current was increased by electron-beam induced surface defects, while the enhancement of on/off property and the decrease of leakage current appeared in the 2 MeV irradiated sample. From the deep level transient spectroscopy measurements for these samples, it showed that the defect states with the activation energies of $E_c$-0.33 eV and $E_v$+0.8 eV are generated during the high energy electron-beam irradiation. Especially, it considered that the $E_c$-0.33 eV state related with O-vacancy affects to their electrical properties.
이동욱,Lee, Dong-Uk 한국건강관리협회 2005 한국건강관리협회지 Vol.3 No.2
Passive smoking is the involuntary inhalation of tobacco smoke by a person, especially a non-smoker, who occupies and area with smokers or a smoker. Passive smoking may cause eye and nose irritation, sore throat, headache, cough to everyone, and it is known that non-smokers have the same kinds of illness with smokers. Smoking rate among the adults aged over 20 in Korea is higher than that of the US or European conturies. Therefore we suppose that Koreans may be exposured to passive smoking than the people of other conturies. It is necessary that people have the knowledge on the heath problems caused by passive smoking and on prevention from the involuntary inhalation of tobacco smoke. I propose that the smokers should be informed the importance of smoking cessation.
이동욱,서원찬,최재원,Lee, Dong Uk,Seo, Won Chan,Choi, Jae Won 한국강구조학회 2000 韓國鋼構造學會 論文集 Vol.12 No.2
Since vehicles become large and heavy and traffic volume is increased rapidly, many fatigue damages have been reported in bridge members. In order to prevent fatigue damages of bridge members and maintain safety it is essential to perform rational fatigue check. Only one vehicle is loaded on a bridge deck for the fatigue design. But in reality it is seldom that only one vehicle passes on a bridge deck. Usually more than two vehicles are passing on a bridge deck simultaneously. Therefore, it is necessary to consider the influence of simultaneous loading for a rational fatigue design. In this study, the influence of simultaneous loading is investigated by performing stress variation analysis due to vehicle load on the basis of linear superposition method and Monte-Carlo simulation of traffic flow, and then calculating the measure of fatigue damages. 교량에 통행하는 차량의 대형화와 통행교통량의 급격한 증가로 인하여 교량부재에서 피로손상이 많이 보고되고 있다. 교량부재의 피로손상을 방지하고, 안전을 유지하기 위해서 합리적인 피로조사를 실시하여야 한다. 교량의 피로설계에서는 차량 1대만 재하 시키는 방법을 채택하고 있으나, 실제 교량의 상부에 차량이 1대만 통과하는 일은 거의 없다. 통상 교량의 상부에는 복수의 차량이 동시에 재하되므로 합리적인 피로설계를 위해서는 동시재하의 영향을 고려하여야 한다. 본 논문에서는 도로교를 통행하는 차륜하중에 대해 선형중첩법과 교통류의 몬테카를로 시뮬레이션에 의한 변동응력해석을 실시하고, 피로 손상도를 구함으로써 통행차량의 차축하중에 대한 동시재하의 영향에 대해 연구하였다.
강상판(鋼床版) U형(形) 트라프리브 단차용접(段差熔接)이음부(部)의 피로강도(疲勞强度)에 관(關)한 연구(硏究)
이동욱,서원찬,Lee, Dong Uk,Seo, Won Chan 한국강구조학회 1996 韓國鋼構造學會 論文集 Vol.8 No.3
With the adoption of welded joints rather than bolted joints, we investigate the fatigue strength and the fatigue crack initiation of U-type trough rib and welded specimen with misalignment in a steel deck plate. The stress concentration factor of welded specimens with a misalignment is also verified by a finite element method. The main conclusions obtained from this study are as follows Experimental results of full-scaled U-type trough rib models have indicated that fatigue life depends on misalignments of welded joints in steel deck plate ; The more misalignments are, the less the fatigue life is. It has also shown that fatigue crack propagates from the welded root to the bead surface. We have also obtained the same results from both the fatigue test of welded specimens with a misalignment and the stress analysis of a finite element method.
마그네슘 합금의 방청을 위한 하이브리드 졸-겔 코팅제의 개발
이동욱 ( Dong Uk Lee ),김영훈 ( Young Hoon Kim ),문명준 ( Myung Jun Moon ) 한국부식방식학회(구 한국부식학회) 2018 Corrosion Science and Technology Vol.17 No.1
The high rate of corrosion of magnesium alloys makes it limited for industrial applications. Therefore, surface treatment is required to enhance their corrosion resistance. In our study, a chemical conversion coating for protecting the corrosion of the magnesium alloy, AZ31B, was prepared by using a phosphate-permanganate solution. The chemical conversion coating had a limited protection ability due to defects arising from cracks and pores in the coating layer. The sol-gel coating was prepared by using trimethoxymethylsilane (MTMS) and 3-glycidoxypropyltrimethoxysilane (GPTMS) as precursors, and aluminum acetyl acetonate as a ring opening agent. The corrosion protection properties of sol-gel and conversion coatings in 0.35wt% NaCl solution were measured by the electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization test. The EIS results indicated that the resistance of the chemical conversion coating with the sol-gel coating was significantly improved through the sol-gel sealed phosphate-permanganate conversion coating. The results of the potentiodynamic polarization test revealed that the sol-gel coating decreased the corrosion current density (I<sub>corr</sub>). The SEM image showed that the sol-gel coating sealed conversion coating and improved corrosion protection.