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객체 지향적 슬레이브 로봇들로 구성된 홈서비스 로봇 시스템의 구현
고창건(Chang-gun Ko),고대건(Dae-gun Ko),권혜진(Hye-jin Kwan),박정일(Jung-il Park),이석규(Suk-gyu Lee) 대한전기학회 2007 대한전기학회 학술대회 논문집 Vol.2007 No.4
This paper proposes a new paradigm for cooperation of multi-robot system for home service. For localization of each robot, the master robot collects information of location of each robot based on communication of RFID tag on the floor and RFID reader attached on the bottom of the robot. The Master robot communicates with slave robots via wireless LAN to check the motion of robots and command to them based on the information from slave robots. The operator may send command to slave robots based on the HRI(Human - Robot Interaction) screened on masted robot using information from slave robots. The cooperation of multiple robots will enhance the performance comparing with single robot.
Ko, Young Gun,Chun, Yong Jin,Kim, Choong Hyun,Choi, Ung Su Elsevier 2011 Journal of hazardous materials Vol.194 No.-
<P><B>Graphical abstract</B></P><P><ce:figure id='fig0005'></ce:figure></P><P><B>Highlights</B></P><P>► The crystal growth of Cu(II) ions on the novel chelating fiber. ► Adsorption capacity of Cu(II) and Cr(VI) ions in the chelating fiber packed column. ► This work demonstrates the adsorption process system with the chelating fiber for the removal of Cu(II) and Cr(VI) ions in the aqueous solution.</P> <P><B>Abstract</B></P><P>Herein, we demonstrate the adsorption process system with the diethylenetriamne coupled polyacrylonitrile fiber for the removal of Cu(II) and Cr(VI) ions in the aqueous solution. The synthesized chelating fiber showed a high adsorption capacity of 11.4mequiv/g. Interestingly, the crystal growth of copper ions on the chelating fiber was observed during the adsorption process. The chelating fiber packed column showed the high performance of the removal of Cu(II) in the aqueous solution due to the distinct characteristic of the crystal growth of metal ions on the chelating fiber. After Cu(II) adsorption on the chelating fiber, the color of the fiber changed to light blue from yellow. The isotherm parameter <I>n</I> of 1.991 was obtained with Freundlich isotherm model for the adsorption equilibrium study which indicates that Cu(II) adsorption on the chelating fiber is very favorable due to <I>n</I>>1. The pseudo-first-order and pseudo-second-order model equations were used for the kinetic study.</P>
Cavitation Behavior of Ultra-Fine Grained Ti-6Al-4V Alloy Produced by Equal-Channel Angular Pressing
Ko, Young Gun,Kwon, Yong Nam,Lee, Jung Hwan,Shin, Dong Hyuk,Lee, Chong Soo Trans Tech Publications, Ltd. 2007 Materials science forum Vol.551 No.-
<P>Cavitation behavior during superplastic flow of ultra-fine grained (UFG) Ti-6Al-4V alloy was established with the variation of grain size and misorientation. After imposing an effective strainup to 8 via equal-channel angular pressing (ECAP) at 873 K, alpha-phase grains were markedly refined from 11 μm to ≈ 0.3 μm, and misorientation angle was increased. Uniaxial-tension tests were conducted for initial coarse grained (CG) and two UFG alloys (ε = 4 and 8) at temperature of 973 K and strain rate of 10-4 s-1. Quantitative measurements of cavitation evidenced that both the average size and the area fraction of cavities significantly decreased with decreasing grain size and/or increasing misorientation. It was also found that, when compared to CG alloy, cavitation as well as diffused necking was less prevalent in UFG alloys, which was presumably due to the higher value of strain-rate sensitivity. Based on the several theoretical models describing the cavity growth behavior, the cavity growth mechanism in UFG alloys was suggested.</P>
Ko, Young Gun,Lee, Dong Seong,Lee, Gil Sun,Choi, Ung Su,Park, Yong Sung,Yoo, Ki Pung WILEY‐VCH Verlag 2011 Macromolecular Chemistry and Physics Vol.212 No.14
<P><B>Abstract</B></P><P>The synthesis of ionic polymer, its solvent‐induced switching behavior, the fabrication of membranes with the thermal‐induced phase separation method (TIPS), and Li<SUP>+</SUP> adsorption isotherm on the membranes are described. The polymer membranes prepared with TIPS method show various textures with polymer concentrations. The adsorption isotherm curves of Li<SUP>+</SUP> on PEVSA samples show that good adsorption capacity is shown at high pH values, according to the S‐shape of the adsorption isotherm. The ionic polymer film displays the different wettability and morphology after treatments in DI water, dichloromethane, and toluene, and its solvent‐induced surface properties are reversible corresponding to solvents. </P>
Ko, Young Gun,Lee, Hyun Jeong,Park, Yong Sung,Woo, Je Wan,Choi, Ung Su The Royal Society of Chemistry 2013 Physical chemistry chemical physics Vol.15 No.39
<P>Herein, the mixing effect of amine and carboxyl groups on electrorheological (ER) properties has been presented with the chitosan and alginic acid dispersed suspensions. Chitosan (for the amine group) and alginic acid (for the carboxyl group) are used to investigate the mixing effect of the amine and carboxyl groups on ER properties with the control of their mixing ratio in the silicone oil. The surface-chemical structure of the mixture of the chitosan and alginic acid particles in the silicone oil is demonstrated by <I>in situ</I> Fourier transform infrared (FT-IR) spectroscopy at various electric fields for the first time. This study focuses on whether the mixture of chemical groups in the ER fluid can promote ER properties or not, and <I>in situ</I> FT-IR analysis of the interface between ER particles in the silicone oil at various DC electric fields. The ER fluids exhibited the increase of the yield stress values with the increase of the counter group addition up to the weight ratio of 50 : 50 (chitosan : alginic acid). A noteworthy result is that the mixing effect of the amine and carboxyl groups resulting in enhanced ER properties is clearly proved. In the <I>in situ</I> FT-IR study, the complex form of amine and carboxyl groups of particles in the ER fluid was confirmed under the electric field.</P> <P>Graphic Abstract</P><P>The surface-chemical structure of aligned chitosan–alginic acid particles in the silicone oil under the DC electric field is demonstrated by <I>in situ</I> FT-IR. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c3cp51907d'> </P>
Gelation of natural polymer dispersed suspensions under electric field
Ko, Young Gun,Choi, Ung Su The Royal Society of Chemistry 2012 SOFT MATTER Vol.8 No.2
<p>Potential applications for natural polymers have been intensively researched for a long time. Electrorheological (ER) fluids are a kind of colloidal suspension with rheological properties that can reversibly change over several orders of magnitude under a sufficiently strong electric field within a millisecond. By extension of the study on the properties of natural polymers to enlarge their applications, herein, we briefly review the ER materials based on natural polymers such as cellulose, starch, and chitosan. This highlight focuses on the current research of ER materials based on natural polymers and their perspective.</p> <P>Graphic Abstract</P><P>This highlight briefly reviews the electrorheological materials and the current researches for their applications based on natural polymers such as cellulose, starch, and chitosan. <img src='http://pubs.rsc.org/ej/SM/2011/c1sm06400b/c1sm06400b-ga.gif'> </P>
Hierarchically Porous Aminosilica Monolith as a CO<sub>2</sub> Adsorbent
Ko, Young Gun,Lee, Hyun Jeong,Kim, Jae Yong,Choi, Ung Su American Chemical Society 2014 ACS APPLIED MATERIALS & INTERFACES Vol.6 No.15
<P>A facile strategy is successfully developed for the centimeter-scale preparation of hierarchically porous aminosilica monolith as a CO<SUB>2</SUB> adsorbent just by simple processes of solvent-evaporation-induced coating, self-assembly, and concentration of tetraethyl orthosilicate sol on the surface of a polymer foam template without any adhesive composite material or hydrothermal treatment. (3-Aminopropyl) trimethoxysilane is immobilized on the surface of silica monolith via a gas-phase procedure. The silica frameworks of the monolith mimic those of the polymer foam template at the macroscale, and the frameworks are composed of the SBA-15 structure at the nanoscale. The hierarchically porous structure demonstrates improved properties over the single-mode porous component, with the macroporous framework ensuring mechanical stability and good mass transport properties, while the smaller pores provide the functionality for CO<SUB>2</SUB> adsorption.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2014/aamick.2014.6.issue-15/am5029022/production/images/medium/am-2014-029022_0010.gif'></P>
Superplastic deformation behavior of ultra-fine-grained 5083 Al alloy using load-relaxation tests
Ko, Young Gun,Shin, Dong Hyuk,Park, Kyung-Tae,Lee, Chong Soo Elsevier 2007 Materials science & engineering. properties, micro Vol.449 No.-
<P><B>Abstract</B></P><P>In this study, superplastic deformation behavior of ultra-fine-grained (UFG) 5083 Al alloy was investigated in the context of inelastic deformation theory. By imposing an effective strain of 8 <I>via</I> equal-channel angular pressings, most of the grains were significantly refined to 0.3μm with non-equilibrium boundaries. A series of tension and load-relaxation tests was carried out to measure elongations and to obtain flow curves of UFG alloy at strain rates of 10<SUP>−4</SUP> to 10<SUP>−2</SUP>s<SUP>−1</SUP> and at temperatures of 498–548K corresponding to 0.58–0.65 <I>T</I><SUB>m</SUB>. The UFG alloy exhibited much higher elongations than the coarse grain alloy at the same temperatures and strain rates, indicating that low-temperature superplasticity was achieved by UFG alloy in spite of its non-equilibrium grain boundaries. Quantitative analysis on deformation mechanisms of UFG alloy was made and compared with those of coarse grain alloy.</P>