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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,Hamad, Kotiba Elsevier 2018 Materials science & engineering. properties, micro Vol.733 No.-
<P><B>Abstract</B></P> <P>In the present work, we investigated the effect of annealing on microstructural evolution and associated mechanical properties of 5052 Al alloy samples subjected to a severe plastic deformation by differential speed rolling (DSR) process. To achieve that, the DSR-deformed samples were isochronally annealed for 1 h at temperatures from 423 K to 523 K with intervals of 25 K. The results clearly indicated that the severe plastic deformation by the DSR followed by the annealing can significantly change the structure, and thus, enhance the related performance of the 5052 Al alloy.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Ko, Young Gun,Lee, Kang Min,Shin, Dong Hyuk The Japan Institute of Metals 2011 MATERIALS TRANSACTIONS Vol.52 No.8
<P>The paper demonstrated the electrochemical corrosion properties of the oxide film of AZ91 Mg alloy subjected to plasma electrolytic oxidation (PEO) coating in an electrolyte containing zirconia and additional heat treatment. Surface observation revealed that a number of zirconia particles were successfully incorporated and were also uniformly distributed throughout the oxide film. After subsequent heat treatment, the relative fraction of Mg(OH)<SUB>2</SUB> decreased whilst the fraction of MgO increased in the oxide film due to the dehydration reaction at 423 K. From the results of electrochemical impedance spectroscopy, the excellent corrosion resistance of AZ91 Mg alloy could be achieved via PEO coating together with annealing treatment. Electrochemical response underlying corrosion response of the present alloy was discussed in relation to equivalent circuit model.</P>
Ko, Young Gun,Hamad, Kotiba Elsevier 2018 Materials science & engineering. properties, micro Vol.726 No.-
<P><B>Abstract</B></P> <P>This work studied the thermal stability of ultrafine grain interstitial-free (IF) steel fabricated by differential speed rolling. The IF steel samples were rolled with the total strain of ~ 1.7 and annealed at 773 K for 30 min - 4 h. The high thermal stability was achieved after annealing for 30 min. Thermal stability was also analyzed by the calculations of activation energy for grain growth of ultrafine grain IF steel and the mechanical behaviors into consideration.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Microstructural influence on low-temperature superplasticity of ultrafine-grained Ti–6Al–4V alloy
Ko, Young Gun,Kim, Woo Gyeom,Lee, Chong Soo,Shin, Dong Hyuk Elsevier 2005 Materials science & engineering. properties, micro Vol.410 No.-
<P><B>Abstract</B></P><P>Microstructural influence on low-temperature superplastic behavior of ultrafine-grained Ti–6Al–4V alloy fabricated by equal channel angular pressing (ECAP) was investigated. The deformed structures were analyzed with the increment of strain by transmission electron microscopy. Also, a series of tensile tests were carried out on ultrafine-grained (UFG) samples to measure elongation at temperature of 973K and at strain rates of 10<SUP>−4</SUP> to 10<SUP>−2</SUP>s<SUP>−1</SUP>. The results indicated that elongation was significantly increased with increasing ECAP straining from 4 to 8 revealing more high-angle grain boundaries. Deformation mechanisms for UFG structure were analyzed in the context of inelastic deformation theory, which consisted of dislocation glide and grain boundary sliding.</P>
Pinecone-like Cu(II) crystal growth on the surface of amine-group-immobilized polymers
Ko, Young Gun,Shin, Dong Hun,Choi, Ung Su Wiley Subscription Services, Inc., A Wiley Company 2005 Journal of polymer science Part A, Polymer chemist Vol.43 No.6
<P>Field-emission scanning electron microscopy (FESEM) was used to monitor pinecone-like Cu(II) crystal growth on polymeric fibers for various growth times. In FESEM images, Cu(II) complexes and Cu(OH)<SUB>2</SUB> crystal growth on poly(acryloamidino ethylene amine) and poly(acryloamidino diethylenediamine) were observed. Up to an elapsed time of 16 min, crystal growth was observed in only one direction. However, after an elapsed time of 20 h, pinecone-like crystals covered the entire surfaces of the synthesized polymers. Fourier transform infrared spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy were used for analysis. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1238–1247, 2005</P> <B>Graphic Abstract</B> <P>Cu(II) complexes and Cu(OH)<SUB>2</SUB> crystal growth on poly(acryloamidino ethylene amine) (a chelating polymer) were observed at various elapsed growth times. Up to an elapsed time of 16 min, crystal growth was observed in only one direction. After an elapsed time of 20 h, pinecone-like crystals covered the entire surface of synthesized poly(acryloamidino ethylene amine) fiber. <img src='wiley_img/0887624X-2005-43-6-POLA20619-gra001.gif' alt='wiley_img/0887624X-2005-43-6-POLA20619-gra001'> </P>
Ko, Young Gun,Hamad, Kotiba Elsevier 2018 Journal of alloys and compounds Vol.744 No.-
<P><B>Abstract</B></P> <P>In this work, we investigated a differential speed rolling (DSR) process as a possible strategy to improve the mechanical properties of AZ31 Mg alloy. For this purpose, the effect of four different routes on microstructure and properties of the alloy were investigated: forward rolling (FR), reverse rolling (RR), turned rolling (TR), turned-reverse rolling (TRR). The microstructure features of the DSR-deformed alloy, including microstructure homogeneity, grain size and grain boundaries revealed that the TR route, in which the sample is rotated 180° around its rolling direction, is the most effective route to obtain an equiaxed, homogenous and fine-grained structure. This was attributed to the intersecting of shear bands during the successive DSR passes. In addition, this route resulted in a weak basal texture. The evolution of such structural features figured out the improved performance, in which a combination of high yield strength (∼295 MPa) and improved ductility (∼21%) were obtained.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The effect of the DSR route on the structure and properties of AZ31 Mg alloy was studied. </LI> <LI> Four different DSR routes were investigated: FR, RR, TRR and TR. </LI> <LI> The results showed that the TR route is the most effective to refine the structure and to enhance the properties. </LI> </UL> </P>