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Finite Element Analysis of Tire Traction Using a Rubber-Ice Friction Model

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Open Journal of Applied Sciences 2018年第11期8卷 495-505页

作者： hyun Chul Jung woo Cheol Park Kyoung moon Jeong R&D Center Kumho Tire Co. Inc. Yongin South Korea

The friction of road surface covered by snow or ice is very low and that results in reducing vehicle traction forces and potential traffic accidents. In general, to establish a master curve on a rubber-ice friction model is difficult because the ice surface, being not far removed from its melting point, reacts itself very sen-sitively to pressure, speed, and temperature changes. In this paper, an accepta-ble frictional interaction model was implemented to finite element method to rationally examine the frictional interaction behavior on ice between the tire and the road surface. The formula of friction characteristic according to tem-perature and sliding velocity on the ice surface was applied for tire traction analysis. Numerical results were verified by comparing the outdoor test data and it was confirmed to indicate similar correlation. It is found that the rub-ber-ice friction model will be useful for the improvement of the ice traction performance of tire.

关键词： Tire Ice Surface Finite Element Method Frictional Model Temperature Slid-ing Velocity

Antimicrobial effect of alexidine and chlorhexidine against Enterococcus faecalis infection

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International Journal of Oral Science 2013年第1期5卷 26-31页

作者： hyun-Shik Kim Seok woo Chang Seung-Ho Baek Seung hyun Han Yoon Lee Qiang Zhu Kee-Yeon Kum Department of Conservative Dentistry Dental Research Institute and BK21 ProgramSeoul National University Dental HospitalSeoul National University School of Dentistry Department of Conservative Dentistry School of DentistryKyung Hee University Department of Oral Microbiology and Immunology Dental Research Institute and BK21 ProgramSeoul National University Dental HospitalSeoul National University School of Dentistry Department of Dentistry Wonju College of Medicine Yonsei University Division of Endodontology School of Dental MedicineUniversity of Connecticut Health Center

A previous study demonstrated that alexidine has greater affinity for the major virulence factors of bacteria than *** aim of this study was to compare the antimicrobial activity of 1%alexidine with that of 2%chlorhexidine using Enterococcus faecalis-infected dentin *** bovine dentin blocks were prepared and randomly divided into six groups of 10 *** was inoculated on 60 dentin blocks using the Luppens apparatus for 24 h and then the dentin blocks were soaked in 2%chlorhexidine or 1%alexidine solutions for 5 and 10 min,*** saline was used as a *** antimicrobial efficacy was assessed by counting the number of bacteria adhering to the dentin surface and observing the degradation of bacterial shape or membrane rupture under a scanning electron *** fewer bacteria were observed in the 2%chlorhexidine-or 1%alexidine-soaked groups than in the control group(P0.05).Ruptured or antiseptic-attached bacteria were more frequently observed in the 10-min-soaked chlorhexidine and alexidine groups than in the 5-min-soaked chlorhexidine and alexidine *** conclusion,10-min soaking with 1%alexidine or 2%chlorhexidine can be effective against *** infection.

关键词： alexidine antibacterial effect chlorhexidine Enterococcus faecalis Luppens apparatus root canal soaking scanning electron microscope

Does hemispheric lateralization influence therapeutic effects of transcranial direct current stimulation?

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Neural Regeneration Research 2016年第1期11卷 126-129页

作者： Yong hyun Kwon Kyung woo Kang Na Kyung Lee Sung Min Son Department of Physical Therapy Yeungnam University College Department of Physical Therapy College of Rehabilitation Science Daegu University Department of Physical Therapy College of Health Science Cheongju University

This study investigated the effect of transcranial direct current stimulation（t DCS） polarity depending on lateralized function of task property in normal individuals performing visuomotor and simple repetitive tasks. Thirty healthy participants with no neurological disorders were recruited to participate in this study. Participants were randomly allocated into active or control condition. For the active condition, t DCS intensity was 2 m A with stimulation applied for 15 minutes to the right hemisphere（t DCS condition）. For the sham control, electrodes were placed in the same position, but the stimulator was turned off after 30 seconds（sham condition）. The tapping and tracking task tests were performed before and after for both conditions. Univariate analysis revealed significant difference only in the tracking task. For direct comparison of both tasks within each group, the tracking task had significantly higher Z score than the tapping task in the t DCS group（P 〈 0.05）. Thus, our study indicates that stimulation of the right hemisphere using t DCS can effectively improve visuomotor（tracking） task over simple repetitive（tapping） task.

关键词： nerve regeneration transcranial direct current stimulation visuomotor task tracking task task property hemispheric lateralization neural regeneration

Structural considerations in friction welding of hybrid Al_2O_3-reinforced aluminum composites

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Transactions of Nonferrous Metals Society of China 2011年第A1期21卷 42-46页

作者： In-Duck PARK Choon-Tae LEE hyun-Soo KIM woo-Jin CHOI Myung-Chang KANG Busan Metropolitan City Hall Fundamental Industries Division 2001 Jungang-ro Yeonje-gu Busan 611-735 Korea Department of Automotive & Mechanical Engineering Silla University Research & Development Center Sam-Ho precision 1256-1 Daejeo2-dong Gangseo-gu Busan 618-807 Korea National Core Research Center for Hybrid Materials Solution Pusan National University

Comparative studies on the relationship between the welding parameters and joining efficiency in the friction welding of hybrid Al203-reinforced aluminum composites were conducted. Metal matrix composites （MMCs） with 37% （volume fraction） aluminum particle were joined by friction welding. The results show that the effects of the rotation speed on the reduction rate of particle size are greater than those of the upset pressure, and the area of the MMC weld zone decreases as the joining efficiency increases, while it is considered that the joining efficiency does not increase as the reduction rate of particle size decreases. During the macro-examination of the bonding interlace, a gray discolored region was observed on the bonding interface, and the center of the region was dark gray. After the micro-examination of the bonding interface, base metal made some second particulate formed by condensed alumina particulate but discoloration part distributed minute alumina particulate without second particulate. Consequently, it was also observed that rotational speed of 3 000 r/min and upset pressure of 63.6 MPa showed a very ***.

关键词： friction welding hybrid aluminum composite bonding interface joining efficiency metal matrix composite

Neuroprotective effects of roasted licorice,not raw form,on neuronal injury in gerbil hippocampus after transient forebrain ischemia

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Acta Pharmacologica Sinica 2006年第8期27卷 959-965页

作者： In-koo HWANG Soon-sung LIM Kyu-hyun CHOI Ki-yeon YOO hyun-kyung SHIN Eun-ji KIM Jung-han YOONPARK Tae-cheon KANG Young-sup KIM Dae-young KWON Dong-woo KIM Won-kook moon Moo-ho WON Korea Central Research Institute.Natural F&P Co Ltd Chunchon 200-160Korea Silver Biotechnology Research Center Korea Silver Biotechnology Research Center Department of Food Science and Nutrition Hallym UniversityChunchon 200-702Korea Medical Science Division Korea Research Institute of Chemical TechnologyYuseong.Daejeon 305-343Korea Korea Central Research Institute.Natural F&P Co Ltd Chunchon 200-160Korea Korea Silver Biotechnology Research Center

Aim:To observe neuroprotective effects of raw and roasted licorice against hy-poxia and ischemic ***:When elucidating the protective effects ofraw and roasted licorice,we analyzed the lactate dehydrogenase (LDH) releaseusing PC12 cells after hypoxia in an in vitro study and after transient forebrainischemia in an in vivo study on Mongolian ***:Raw and roastedlicorice significantly reduced LDH release from PC12 cells exposed to an hypoxicchamber for *** the roasted licorice-treated group,the decrease of LDH releasewas more pronounced compared to that of the raw licorice-treated *** licorice-treated animals,approximately 66%-71% of CA1 pyramidal cellsin the ischemic hippocampus were stained with cresyl violet compared to thecontrol ***,in the raw licorice-treated animals,no significantneuroprotection against ischemic damage was *** addition,ischemic ani-mals in roasted licorice-treated group maintained the Cu,Zn-superoxide dismutase(SOD1) activity and protein levels compared to the control group,while in rawlicorice-treated group SOD1 activity and protein levels were reduced *** pressure liquid chromatography analysis showed that non-polar compoundscontaining glycyrrhizin-degraded products,such as glycyrrhetinic acid (GA) andglycyrrhetinic acid monoglucuronide (GM),were increased in roasted ***:Roasted licorice had neuroprotective effects against ischemic dam-age by maintaining the SOD1 *** addition,the difference in protectiveability between raw and roasted licorice may be associated with non-polarcompounds,such as GA and GM.

关键词： transient ischemic attack roasted licorice raw licorice neurons PC12 cells hippocampus pyramidal cells Gerbillinae superoxide dismutase

Distribution of electric field for carbon nanotube assembly: Experiments (II)

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Transactions of Nonferrous Metals Society of China 2011年第A1期21卷 121-125页

作者： Soongeun KWON Soo-hyun KIM Kwang-ho KIM Myung-chang KANG hyung-woo LEE Department of Mechanical Engineering Korea Advanced Institute of Science and Technology (KAIST) Daejeon 305-701 Korea National Core Research Center for Hybrid Materials Solution Pusan National University

The distribution effect of electric field on the alignment and attachment of carbon nanotubes （CNTs） were investigated. The experimental results were compared with the simulation results according to three different shaped electrodes. In previous simulation, the round shaped electrodes were expected to be more effective for aligning and attaching a single CNT between two electrodes than conical or rectangular shaped electrodes. To verify the simulation results, three different shaped electrodes were introduced and a single multi-walled carbon nanotube （MWNT） was attached. The optimal conditions for aligning and attaching MWNTs such as the frequency, applied voltage and concentration of MWNTs solution were investigated. Through repeated experiments, frequency of 100 kHz-10 MHz, applied voltage of 0.3-1.3 V^s/~m, concentration of 5 ktg/mL in MWNTs solution were obtained as a possible condition range to attach MWNTs. Under these conditions, the yield of MWNTs attachment between two electrodes was up to 70%. In previous simulation, furthermore, it was verified that the size of the stable or quasi-stable region made CNTs aligned and attached on different shaped electrodes from the comparison of the experimental and simulation results. Most single MWNT attachment was accomplished on the round shaped electrodes.

关键词： carbon nanotubes dielectrophoresis round shaped electrode simulation

Is effect of transcranial direct current stimulation on visuomotor coordination dependent on task difficulty?

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Neural Regeneration Research 2015年第3期10卷 463-466页

作者： Yong hyun Kwon Kyung woo Kang Sung Min Son Na Kyung Lee Department of Physical Therapy Yeungnam University College Department of Physical Therapy College of Rehabilitation ScienceDaegu University Department of Physical Therapy College of Health Science Cheongju University

Transcranial direct current stimulation （tDCS）, an emerging technique for non-invasive brain stimulation, is increasingly used to induce changes in cortical excitability and modulate motor behavior, especially for upper limbs. The purpose of this study was to investigate the effects of tDCS of the primary motor cortex on visuomotor coordination based on three levels of task difficulty in healthy subjects. Thirty-eight healthy participants underwent real tDCS or sham tDCS. Using a single-blind, sham-controlled crossover design, tDCS was applied to the primary motor cortex. For real tDCS conditions, tDCS intensity was 1 mA while stimulation was applied for 15 minutes. For the sham tDCS, electrodes were placed in the same position, but the stimu- lator was turned off after 5 seconds. Visuomotor tracking task, consisting of three levels （levels 1, 2, 3） of difficulty with higher level indicating greater difficulty, was performed before and after tDCS application. At level 2, real tDCS of the primary motor cortex improved the accurate index compared to the sham tDCS. However, at levels 1 and 3, the accurate index was not significantly increased after real tDCS compared to the sham tDCS. These findings suggest that tasks of mod- erate difficulty may improve visuomotor coordination in healthy subjects when tDCS is applied compared with easier or more difficult tasks.

关键词： neural regeneration transcranial direct current stimulation visuomotor coordination task difficulty primary motor area motor learning neural regeneration

Rapid detection of influenza A(H1N1)virus by conductive polymer-based nanoparticle via optical response to virus-specific binding

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Nano Research 2022年第3期15卷 2254-2262页

作者： Geunseon Park hyun-Ouk Kim Jong-woo Lim Chaewon Park Minjoo Yeom Daesub Song Seungjoo Haam Department of Chemical&Biomolecular Engineering Yonsei UniversitySeoul 03722Republic of Korea Division of Chemical Engineering and Bioengineering College of Art Culture and EngineeringKangwon National UniversityChuncheon-siGangwon-do 24341Republic of Korea Biohealth-machinery Convergence Engineering Kangwon National UniversityChuncheonGangwon-do 24341Republic of Korea College of Pharmacy Korea UniversitySejong 30019Republic of Korea

A recurrent pandemic with unpredictable viral nature has implied the need for a rapid diagnostic technology to facilitate timely and appropriate countermeasures against viral *** this study,conductive polymer-based nanoparticles have been developed as a tool for rapid diagnosis of influenza A(H1N1)*** distinctive property of a conductive polymer that transduces stimulus to respond,enabled immediate optical signal processing for the specific recognition of H1N1 *** poly(aniline-co-pyrrole)-encapsulated polymeric vesicles,functionalized with peptides,were fabricated for the specific recognition of H1N1 *** low solubility of conductive polymers was successfully improved by employing vesicles consisting of amphiphilic copolymers,facilitating the viral titer-dependent production of the optical *** optical response of the detection system to the binding event with H1N1,a mechanical stimulation,was extensively analyzed and provided concordant information on viral titers of H1N1 virus in 15 *** specificity toward the H1N1 virus was experimentally demonstrated via a negative optical response against the control group,***,the designed system that transduces the optical response to the target-specific binding can be a rapid tool for the diagnosis of H1N1.

关键词： influenza A(H1N1)virus conductive polymer optical property rapid detection

Effect of Post-Rolling after ECAP on Superplastic Behavior of Commercial Al-Mg Alloy

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Journal of Rare Earths 2004年第Z2期22卷 53-56页

作者： Dong Hyuk Shin Byung Du Ahn hyun Soo woo Kyeom Kim Kyung-Tae Park Department of Metallurgy and Materials Science Hanyang UniversityAnsan 425-791Korea Department of Metallurgy and Materials ScienceHanyang UniversityAnsan 425-791Korea Department of Metallurgy and Materials ScienceHanyang UniversityAnsan 425-791Korea Department of Metallurgy and Materials ScienceHanyang UniversityAnsan 425-791Korea Division of Advanced Materials Science & EngineeringHanbat National UniversityTaejon 305-719Korea

A commercial Al-Mg alloy was subjected to equal channel angular pressing of 4 passes with and without postrolling, and the effects of post-rolling on the deformation characteristics of the alloy at 723 K were examined. Post-rolling was found to influence the deformation behavior significantly. The deformation behavior of the alloy processed only by equal channel angular pressing was characterized by (a) localized deformation indicated by severe surface prominence and depression, (b) the strain rate sensitivity of 0.33, and (c) moderate high strain rate superplastic elongations. By contrast, that of the alloy processed by equal channel angular pressing and post-rolling (70 % thickness reduction) was manifested by (a) uniform deformation associated with grain boundary sliding throughout the sample, (b) a sigmoidal behavior showing the strain rate sensitivity of 0.45 at the intermediate strain rates in the logarithmic stress-strain rate curve, and (c) very large high strain rate superplastic elongations.

关键词： high superplasticity equal channel angular pressing rolling deformation mechanisms rare earths