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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.
양시우(Siwoo Yang),김남욱(Namwook Kim),박영일(Yoengil Park),임원식(Wonsik Lim),차석원(Sukwon Cha),양호림(Horim Yang) 한국자동차공학회 2007 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Power split HEV systems such as THS have several control variables. Contrary to conventional internal combustion vehicles when torque is inputted from a driver at specified vehicle speed, torques and speeds of engine and two motors should be determined. There is a relationship between variables that satisfies required output state, however solutions show considerably different fuel efficiency with changing Battery SOC. To find optimal control values, firstly calculates the efficiency of a HEV system composed of one engine, two motors and a planetary gear system. The efficiency of a HEV system includes engine efficiency, motor efficiency and power recirculation. Based on the constructed system efficiency map, optimal points can be determined with fixing a SOC level at specific output state. Then the only remained task which is changeable at discretion is determining SOC levels. By dynamic programming the optimized SOC path can be obtained easily. The results of this simulation shows some tendencies that are applicable to a cruising control strategy.
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.
복합 유성기어를 이용한 듀얼모드 하이브리드 자동차의 가속성능 최적화
양시우(Yang, Si-U),김남욱(Kim, Nam-Wook),양호림(Yang, Ho-Rim),박영일(Park, Yoeng-Il),차석원(Cha, Suk-Won) 한국신재생에너지학회 2006 한국신재생에너지학회 학술대회논문집 Vol.2006 No.11
Accelerating ability is one of the most important performance of the vehicle. Unlike conventional internal combustion vehicles and power-assist hybrid vehicles, the maximized acceleration of dual mode hybrid vehicles is not simply. achieved by maximizing engine or motor torque Because of the dynamic stability of planetary gear, speeds and torques control of engine, motor 1 and motor 2 is essential and according to control value, acceleration performance is changed There are two control values which are velocity and torque for each component totalling six. These six values can be variables for an objective function. However, because three velocity variables can be regarded as only one variable speed ratio and the remaining three torque variables can be solved analytically, without complicated numerical algorithm the solution for the objective function can be obtained. This optimized solution shows the best performance possible to the specified dual mode system.
김남욱(Namwook Kim),양시우(Siu Yang),김기남(Kinam Kim),장현목(Hyeonmog Jang),박영일(Yeong-il Park) 한국자동차공학회 2007 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Coupler systems of trains are composed of buffer or hydraulic elements. These coupler systems can protect the train against the collision because the systems absorb the impact of the collision. The dynamic behavior of the coupler systems depends on the number of the cars which compose the train and stiffness of the cars. To analyze the dynamic behavior of the coupler systems, simulator is introduced in this paper, by which maximum force of the coupler systems and velocity of the cars can be calculated. In general, the first coupler which is attached at the front of the train gets the maximum force at simulation, and the maximum force of the first coupler doesn't relate to the number of the train when the number is bigger than three. The maximum force of the first coupler, however, increases along the stiffness of the cars because the maximum force increases as the period of the impact is shorten. The period approximately can be acquired from the stiffness of the coupler systems and the stiffness of the cars, so the maximum force, which affects the life time of the coupler systems, can be optimized if the coupler system is well designed.
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.
김남욱(Namwook Kim),양시우(Siu Yang),양호림(Horim Yang),조성태(Sungtae Cho),임원식(Wonsik Lim),차석원(Suk won Cha) 한국자동차공학회 2007 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Dual mode hybrid systems are composed of few combined planetary gear sets. One planetary gear set has two DOF(degree of freedom) and the DOF increases when planetary gear sets are added, so it is complicate to analyze the systems. Methodologies of combining the planetary gear sets can be various methods, but it is needed that the methodologies have consistency. To the consistency, the equivalent parameters, α', β', R'a, R'b are introduced in this paper, and the arbitrary system, E-IVT(Electric Infinitely Variable Transmission) developed by Renault, is converted to the equivalent system with these parameters. Furthermore, the system efficiency can be represented by these parameters at hybrid mode, and the strategies of controlling the compound split can be improved by the analysis of the compound splits in this paper.
김남욱(Namwook Kim),이대흥(Dae Heung Lee),양시우(Siu Yang),박영일(Yoeng-il Park),차석원(Suk Won Cha) 한국자동차공학회 2008 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Hybrid system has two compatible power resources, an engine and a battery, and the strategies to control these two power resources cannot be simplified as an explicit algorithm because we'd like to sustain the state of charge of the battery within reasonable revel. Expect debating on how we can make optimal controllers, we might be able to draw the optimal trajectory with optimization methods if we already knew about the schedule of the driving cycle. These paper studies the optimization method of the fuel consumption for hybrid electrical vehicles with the method of Dynamic Programming, which was introduced Richard Bellman. DP is an effective method to get optimal trajectories when the systems have complicated and nonlinear behavior, and where there are several intricate constraints for control variables. We also discussed about the analytical approach for these optimal problems with a method of calculus of variation, which gives us the intuition about the optimal control of the hybrid system.