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Kim B.-S.,Kumoh National Institute of Technology | Park J.-Y.,Kumoh National Institute of Technology | Kim C.-S.,Korea Institute of Energy Research | Kim S.-B.,Kumoh National Institute of Technology | And 4 more authors.
Electrochimica Acta | Year: 2015

Zirconium was newly utilized as a post-treatment material for photoelectrodes in dye-sensitized solar cells (DSSCs), and DSSCs with a high energy conversion efficiency were developed. The Zr oxide-post-treated TiO2 photoelectrodes were prepared by dipping Degussa P25 in a Zr butoxide solution, followed by calcination for 30 min at 475 °C. In the prepared sample, the particle size decreased, and the specific surface area increased, leading to improved dye adsorption. Zr oxide-post-treatment formed ZrO2 on TiO2 surfaces and the electron transport increased by the formation. This post-treatment decreased the recombinant ratio of electrons by reducing resistance in the interparticle electrode/dye/electrolyte. The energy conversion efficiency of Zr oxide-post-treated TiO2 photoelectrodes was 7.03%, which is a 61% improvement over P25 photoelectrodes and is similar to that of TiCl4-post-treated TiO2 photoelectrodes (7.28%). This enhanced energy conversion efficiency could be attributed to the increased surface area, which enabled higher dye loading, and to the improved interparticle connections, which enhanced charge transport and reduced charge recombination. © 2015 Published by Elsevier Ltd.


Han M.K.,Environmental and Energy Systems Research Division | Chang D.L.,Nano Fusion Production System Research Division | Doo H.K.,Nano Fusion Production System Research Division | Kyoung T.P.,Nano Fusion Production System Research Division
ICCAS 2010 - International Conference on Control, Automation and Systems | Year: 2010

This paper deals with a sliding mode impedance control (SMIC) of end-effector of robot manipulator using a tracking control scheme and a real-time artificial intelligence algorithm based on a radial basis function neural networks(RBFNNs). To real-time estimate the design parameters of desired impedance model such as desired inertia, damping, and stiffness desired impedance, SMIC(sliding mode impedance control) with RBFNNs algorithm is proposed. ©ICROS.


Park K.T.,Nano Fusion Production System Research Division | Kim H.M.,Environmental and Energy Systems Research Division
International Conference on Control, Automation and Systems | Year: 2011

This paper deals with robust steering control of 2-DOF(Degree Of Freedom) bicycle model. 2-DOF bicycle model is specialized model for the steering control of vehicle. When the DOF of real vehicle consider more than 2-DOF, 2-DOF model has many system uncertainties. Therefore, to design the steering controller of vehicle based on 2-DOF model, system uncertainty should be included to the process of controller design. Therefore, to satisfy robustness for system uncertainty, sliding mode controller with variable structure controller is designed. In addition, to evaluate the validity of proposed control scheme, computer simulation is executed. © 2011 ICROS.


Park K.T.,Nano Fusion Production System Research Division | Kim D.H.,Nano Fusion Production System Research Division | Kim S.J.,Environmental and Energy Systems Research Division | Kim H.M.,Environmental and Energy Systems Research Division
URAI 2011 - 2011 8th International Conference on Ubiquitous Robots and Ambient Intelligence | Year: 2011

This paper deals with adaptive sliding mode control of servo systems with system uncertainty such as nonlinear friction. In the case of servo systems, friction phenomenon causes the reduction of tracking performance because friction is directly related with various internal and external environment conditions such as the level of lubricant, contamination, and temperature. Therefore, to overcome the problems with friction in servo systems, robust control scheme is required. In addition, to actively compensate system uncertainties, adaptive control scheme can be required. This paper proposes adaptive sliding mode control scheme integrating sliding mode control scheme with robustness property and adaptive control scheme with compensating system uncertainty by on-line estimating unknown parameters. The proposed control scheme is verified through computer simulation. © 2011 IEEE.


Park K.T.,Nano Fusion Production System Research Division | Kim H.M.,Environmental and Energy Systems Research Division
Proceedings of the 28th International Symposium on Automation and Robotics in Construction, ISARC 2011 | Year: 2011

This paper deals with robust position control of electro-hydrostatic actuator (EHA) systems with system uncertainties. EHA systems compared with conventional hydraulic actuator (CHA) systems are controlled by electric motor directly connected to bidirectional pump and its size is much smaller due to the component integration such as a pump, a reservoir, various valves and horses. In addition, EHA systems have fast response property because of high stiffness. Therefore, EHA systems can replace CHA systems as well as satisfy system performance. In spite of the merit of EHA systems, EHA systems in construction field are exposed to many system uncertainties due to the distinct characteristics of construction field. However, it is difficult to measure or estimate system uncertainties. Thus, sliding mode controller (SMC) and radial basis function neural networks (RBFNNs) algorithm are designed to compensate system uncertainties and to achieve robust control performance with EHA systems.


Kim H.M.,Electrical Propulsion Research Division | Lee Y.J.,Autopower Company | Taik P.K.,Environmental and Energy Systems Research Division
International Conference on Control, Automation and Systems | Year: 2012

This paper deals with robust steering control of 2-DOF(Degree Of Freedom) bicycle model. 2-DOF bicycle model is specialized model for the steering control of vehicle. Even if the real vehicles have many system uncertainties such as nonlinearity and disturbance, the 2-DOF bicycle model have been generally used to algorithm development for the steering control of vehicles since the dynamics of the 2-DOF bicycle model is very simple. However, since system uncertainties are omitted to the dynamics of the 2-DOF bicycle model compared with more than 2-DOF vehicle models, it is important to consider the system uncertainties in the design procedure of the steering controller. Therefore, to design the steering controller of vehicle based on 2-DOF model including many system uncertainties, back-stepping control scheme for effectively compensating the system uncertainties is designed in order to compensate the system uncertainties. In addition, to evaluate the validity of proposed control scheme, computer simulation is executed. © 2012 ICROS.


Park C.,Environmental and Energy Systems Research Division | Kim C.,Environmental and Energy Systems Research Division | Choi Y.,Environmental and Energy Systems Research Division | Lee S.,Environmental and Energy Systems Research Division
Journal of Mechanical Science and Technology | Year: 2014

Mixtures of hydrogen and natural gas are promising for improving efficiency and reducing harmful emissions in spark ignition engines, since limits of flammability can be extended while stable combustion is secured. In this research, the combustion characteristics of long electrode spark plugs were evaluated in a hydrogen blended with natural gas (HCNG) engine. Decreases in the flame propagation distance through the use of spark plugs can lead to increased burning rates and further improvement of fuel economy in HCNG engines. An 11-liter heavy duty lean burn engine was employed and performance characteristics including emissions were assessed according to the spark timing of the minimum advance for best torque (MBT) for each operating condition. Retarded MBT spark advance timing with long electrode spark plugs due to increased burning speed supported increases in engine efficiency and reductions of nitrogen oxide (NOx) emissions. The lower positions of initial flame kernels due to the use of long electrode spark plugs were preferable to improvements of cyclic variability due to reduced flame front quenching, and carbon monoxide (CO) emissions at the flammability limit were also improved. © 2014 The Korean Society of Mechanical Engineers and Springer-Verlag Berlin Heidelberg.

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