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Kim, Yoon Young,Kim, Mi-Yeon,Park, Young Min,Kim, Hyung Ok,Koh, Cjae Sook,Lee, Hae Kwang The Korean Academy of Medical Sciences 2008 JOURNAL OF KOREAN MEDICAL SCIENCE Vol.23 No.2
<P>Many patients are currently suffering from nickel (Ni)-induced allergic contact dermatitis (ACD). There have been few Korean studies dealing with the threshold of Ni-induced ACD and quantifying the total amount of Ni in the metal alloys. The aim of this study is to evaluate the amount of Ni leached from metal alloys and Ni contents in metal alloys, and to estimate the threshold of Ni-induced ACD. All the earrings we examined leached below 0.5 µg/cm<SUP>2</SUP>/week, the upper limit of European Union (EU) regulation, but the other metal alloys leached a much higher amount of Ni than the limit. Likewise, all the earrings we examined contained less than 0.05% Ni (500 µg/g), the upper limit of EU regulation, but the other metal alloys exceeded this limit. Twenty Ni-sensitive subjects, who were patch-tested with various concentrations of Ni sulphate, showed positive reactions to 5% and 1% Ni sulphate, 10 subjects showed positive reactions to 0.01%, and the most sensitive subject showed reaction even to 0.0001%. The subjects in this study were more sensitive to Ni than those in the previous studies done in Europe. Taken together, strictly regulating the Ni-containing alloys that are made in Korea is needed to lower the occurrence of Ni-induced ACD.</P>
An Adaptive Control Approach for Improving Control Systems with Unknown Backlash
Kwang Ho Han,Gi Ok Koh,Jaemin Sung,Byoung Soo Kim 한국항공우주학회 2011 International Journal of Aeronautical and Space Sc Vol.12 No.4
Backlash is common in mechanical and hydraulic systems and severely limits overall system performance. In this paper, the development of an adaptive control scheme for systems with unknown backlash is presented. An adaptive backlash inverse based controller is applied to a plant that has an unknown backlash in its input. The harmful effects of backlash are presented. Compensation for backlash by adding a discrete adaptive backlash inverse structure and the gradient-type adaptive algorithm, which provides the estimated backlash parameters, are also presented. The supposed adaptive backlash control algorithms are applied to an aircraft with unknown backlash in the actuator of control surfaces. Simulation results show that the proposed compensation scheme improves the tracking performance of systems with backlash.
Ok, Seon-Yeong,Cho, Kwon-Koo,Kim, Ki-Won,Ryu, Kwang-Sun Royal Swedish Academy of Sciences 2010 Physica scripta Vol.2010 No.t139
<P>Well-ordered TiO<SUB>2</SUB> nanotube arrays were fabricated by the potentiostatic anodic oxidation method using pure Ti foil as a working electrode and ethylene glycol solution as an electrolyte with the small addition of NH<SUB>4</SUB>F and H<SUB>2</SUB>O. The influence of anodization temperature and time on the morphology and formation of TiO<SUB>2</SUB> nanotube arrays was examined. The TiO<SUB>2</SUB> nanotube arrays were applied as a photoelectrode to dye-sensitized solar cells. Regardless of anodizing temperature and time, the average diameter and wall thickness of TiO<SUB>2</SUB> nanotube arrays show a similar value, whereas the length increases with decreasing reaction temperature. The conversion efficiency is very low, which is due to a morphology breaking of the TiO<SUB>2</SUB> nanotube arrays in the manufacturing process of a photoelectrode.</P>