http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
전도식 원자현미경을 이용한 ZnO 나노로드 기반 압전 나노발전기의 사이즈 의존성 평가
양이준,김관래 대한금속·재료학회 2020 대한금속·재료학회지 Vol.58 No.1
ZnO nanorods are one of the most studied materials because it can be facilely grown on a wide range of substrates at low temperature. ZnO exhibits piezoelectricity as well as semiconducting properties, and hence is applicable to piezoelectric nanogenerators and sensors. In the present work, the effect of ZnO nanorods’ size on piezoelectric performance was systematically studied using conductive atomic force microscopy (C-AFM). We measured the total C-AFM signal for an observing area and evaluated the piezoelectric performance of the ZnO nanorods based on this total C-AFM signal. First, five samples of ZnO nanorod with distinct aspect ratios were hydrothermally grown on silicon substrates. Afterwards, two types of AFM tips with different spring constants were used to conduct C-AFM as a function of aspect ratio. When the AFM tip with a 42 N⁄m spring constant was used for the C-AFM measurement, the total C-AFM signal continuously increased with increasing aspect ratio. The total C-AFM signal increased with increasing normal force, but fluctuated with increasing scan rate. The results of the C-AFM experimental measurements were compared with the open-circuit voltage and short-circuit current of ZnO-nanorod based piezoelectric nanogenerator. We show that using C-AFM is a facile and effective method for investigating the optimized aspect ratio of ZnO nanorods for piezoelectric power generation.
양이준,김관래 대한금속·재료학회 2022 대한금속·재료학회지 Vol.60 No.2
Conductive atomic force microscopy (C-AFM) is one of the most commonly used characterization techniques for piezoelectric one-dimensional nanomaterials. However, a comprehensive understanding of the effects of certain scan parameters on the C-AFM signals remains elusive. In the present work, the dependency of C-AFM signals on the normal force, scan speed, and Z scanner feedback gain was studied in conjunction with lateral force microscopy (LFM) signals. As the normal force increased, the C-AFM and the LFM signals increased for the following two possible reasons. When larger normal force was applied, ZnO nanorods were more effectively deflected, intensifying the piezoelectric effect. Additionally, the triboelectric effect was enhanced via the increased force of friction between the AFM tip and the ZnO nanorods. When the scan speed increased to 0.5 Hz, the LFM signals and the C-AFM signals increased owing to the enhanced degree of deflection in the ZnO nanorods. However, when exceeding 0.5 Hz, both the LFM signals and the C-AFM signals started to decrease because the AFM tip did not come into contact with the short ZnO nanorods at a high scan speed. Finally, with an increase in the feedback gain to 0.5, both the LFM signals and the CAFM signals increased. However, when the feedback gain exceeded 1.0, the Z scanner feedback loop was too sensitive to deflect the ZnO nanorod, considerably reducing the total LFM signals. In contrast, the total CAFM signal showed only a moderate decrease.
p-CuO/n-ZnO 이종접합 박막 구조의 수소 가스 특성 평가
양이준,정대웅,맹보희,정동건,이준엽,김영삼,안희경 한국센서학회 2022 센서학회지 Vol.31 No.5
Hydrogen (H2) gas is widely preferred for use as a renewable energy source owing to its characteristics such as environmental friendliness and a high energy density. However, H2 can easily reverse or explode due to minor external factors. Therefore, H2 gas monitoring is crucial, especially when the H2 concentration is close to the lower explosive limit. In this study, metal oxide materials and their pn heterojunctions were synthesized by a hydrothermal-assisted dip-coating method. The synthesized thin films were used as sensing materials for H2 gas. When the H2 concentration was varied, all metal oxide materials exhibited different gas sensitivities. The performance of the metal oxide gas sensor was analyzed to identify parameters that could improve the performance, such as the choice of the metal oxide material, effect of the p-n heterojunctions, and operating temperature conditions of the gas sensor. The experimental results demonstrated that a CuO/ZnO gas sensor with a p-n heterojunction exhibited a high sensitivity and fast response time (134.9% and 8 s, respectively) to 5% H2 gas at an operating temperature of 300oC.
양정욱,김재명,이형운,한선경,이준설,남상식,정미남,송연상,안승현,최인후 한국작물학회 2015 Korean journal of crop science Vol.60 No.1
To analysis of virus free sweetpotato effect, 5 virus free sweetpotato and virus normal sweetpotato varieties were planted in 5 different regions at 2010 year. The average yields of virus free sweetpotato are showed different results according to regions. Sinjami which cultivated at Iksan were increased maximum 68% compare to normal. However, Sinjami which cultivated in Hamyang were decreased yield 11% compare to normal. Analysis of tuber formation ratio of Sinjami, Yenhwangmi, Singeonmi which cultivated in Nonsan were decreased tuber number compare to normal. However, 3 varieties were all increased on Average storage root weight and yield of marketable storage root. In the results of analysis of marketable storage root according to cultivated regions and varieties, all varieties except Sinjami which cultivated in Hamyang were increased yield. Also, quality of virus free sweetpotato were enhanced 7 to 9 compare to virus infected sweet potato which showing average 3. Contents of starch between virus free and virus infected sweetpotato were not affected by virus. Virus free sweetpotato were more increased starch products according to increased total production yield. Also, Brix° (%) was not showing difference between virus free and virus infected sweetpotatoes. In this experiment, Virus free sweetpotato are enhanced production yields and quality. Therefore, we suggested that virus free sweetpotato is one of the methods to reduce damage by sweetpotato virus.