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미세액적 유동반응기 공정에서 연속제조된 나노구조 SiO<sub>2</sub>:Zn 원환형 입자의 특성
양시우,강용,강호,Yang, Si Woo,Kang, Yong,Kang, Ho 한국화학공학회 2018 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.56 No.4
Characteristics of nano-structured $SiO_2:Zn$ hollow powders prepared in the micro drop fluidized reactor process were investigated with respect to bandgap energy and surface activity. The $SiO_2:Zn$ hollow powders were successfully prepared continuously in the one step process with reasonable production efficiency, with varying the amount of THAM (tris(hydroxymethyl)-aminomethane) additive and concentration of $Zn^{2+}$ ions. The doping of $Zn^{2+}$ ions into $SiO_2$ lattice led to the reduction of bandgap energy by forming the acceptor level of $Zn^{2+}$ below the conduction band of $Si^{4+}$ ions. The hollow shape also contributed to reduce the bandgap energy of $SiO_2:Zn$ powders. The doping of $Zn^{2+}$ ions into $SiO_2$ hollow powders could enhance the surface activity by forming SiO-H stretching and oxygen vacancies at the surface of $SiO_2:Zn$ powders. 미세액적 유동반응기 공정에서 제조된 나노구조 $SiO_2:Zn$ 원환형 입자의 특성을 밴드갭 에너지와 표면 반응성의 관점에서 고찰하였다. $SiO_2:Zn$ 원환형 입자를 단일 공정에서 연속적이며 합리적인 생산 효율로 첨가제인 THAM (tris(hydroxymethyl)-aminomethane)과 도핑되는 $Zn^{2+}$ 이온의 농도 변화에 따라 성공적으로 제조할 수 있었다. 그리고 $Zn^{2+}$ 이온의 도핑은 $Si^{4+}$ 이온의 conduction band 보다 에너지 레벨이 낮은 $Zn^{2+}$ 이온의 acceptor level을 형성함으로써 $SiO_2:Zn$ 원환형 입자의 밴드갭 에너지를 줄일 수 있었다. 또한, 입자의 원환형 구조는 $SiO_2:Zn$ 입자의 밴드갭 에너지를 감소시키는데 기여하였다. 따라서 $Zn^{2+}$ 이온이 도핑된 $SiO_2:Zn$ 원환형 입자는 표면에 SiO-H의 형성과 산소 결함의 생성으로 표면 반응성을 증대시킬 것으로 사료되었다.
Nitrate-Citrate 혼합 전구체로부터 ZnO 입자의 합성반응 특성
양시우 ( Si Woo Yang ),이승호 ( Seung Ho Lee ),임대호 ( Dae Ho Lim ),유동준 ( Dong Jun Yoo ),강용 ( Yong Kang ) 한국화학공학회 2016 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.54 No.3
Characteristics of self-propagating reaction for the preparation of ZnO powder from precursors composed of nitrate and citrate compounds were examined. The ratio of C/N was maintained in range of 0.7~0.8 to initiate the selfpropagating reaction between the reducing citrate and oxidizing nitrate groups. The samples were decomposed thermally by using TGA. The sudden decomposition occurred in the range of X > 0.5 in a very short time with a very sharp decrease of mass, indicating that the self-propagating reaction would occur. Friedman, Ozawa-Flynn-Wall and Vyazovkin methods were employed to predict the activation energy, reaction order and frequency factor of the reaction rate in the rate determining step of X < 0.5 range. The activation energy increased with increasing fractional conversion in the range of 46~130 (kJ/min). The reaction order decreased in the range of 2.9~0.9, while the frequency factor increased in the range of 85~278 (min-1), respectively, with increasing the rate of temperature increase.
마이크로 액적/기포 유동반응기에서 ZnO 입자의 연속제조 특성
이승호 ( Seung Ho Lee ),양시우 ( Si Woo Yang ),임대호 ( Dae Ho Lim ),유동준 ( Dong Jun Yoo ),이찬기 ( Chan Ki Lee ),강경민 ( Gyung Min Kang ),강용 ( Yong Kang ) 한국화학공학회 2015 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.53 No.5
Characteristics of continuous preparation of ZnO powder were investigated in a micro drop/bubble fluidized reactor of which diameter and height were 0.03 m and 1.5 m, respectively. The flow rate of carrier gas for transportation of precursors to the reactor was 6.0 L/min and the concentration of Zn ion in the precursor solutions was 0.4 mol/L, respectively. Effects of reaction temperature (973 K~1,273 K) and flow rate of micro bubbles (0~0.4 L/min) on the pore characteristics of prepared ZnO powder were examined. The optimum reaction temperature for the maximum porosity in the ZnO powder was 1,073 K within this experimental condition. The mean size of ZnO powder prepared continuously in the reactor decreased but the surface of the powder became smooth, with increasing reaction temperature. The injection of micro bubbles into the reactor could enhance the formation of pores in the powder effectively, and thus the mean BET surface area could be increased by up to 58%. The mean size of prepared ZnO powder was in the range of 1.25~1.75 μm depending on the reaction temperature.
하이브리드 전기 자동차의 주행 모드에 따른 회생제동 토크 분석
서호원(Howon Seo),이윤호(Yoon Ho Lee),차석원(Suk Won Cha),최종대(Jongdae Choi),양시우(Si Woo Yang) 한국자동차공학회 2011 한국자동차공학회 학술대회 및 전시회 Vol.2011 No.11
Regenerative Braking is main issue of Hybrid Electric Vehicles(HEV). To analysis regenerative braking torque of HEV driving experiment is performed by using a test HEV in various driving modes. Driving modes are CITY MODE, HIGHWAY MODE and ROUTE MODE. Torque is measured by torque sensor attached to driving shaft during experiments. In this study, sheer type strain gages are used to construct torque sensor and telemetric signal amp is used to transport and amplify sensor signal of rotating drive shaft. Torque data of each cycle are sorted by vehicle speed and applied torque range. Characteristic of torque data of each driving mode is represented by time distribution map. Torque data of each driving mode can be used for development of control strategy and criteria of durability test for HEV mechanical components.