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Takeharu HAYASHI,Yoshihiko TAKAHASHI,Keigo HARA,Yasunori TAKEMURA,Satoru YAMAGUCHI 제어로봇시스템학회 2022 제어로봇시스템학회 국제학술대회 논문집 Vol.2022 No.11
To develop sustainable societies, it is necessary to reduce the use of fossil fuels. Therefore, widespread use of electric vehicles (EVs) is the need. Many subjects such as mathematics-and physics-based-mechanics of machine taught at the universities are useful to meet this problem. However, to design EVs, the ability to unify such knowledge along with the fabrication cost, time management, and teamwork management is necessary. We think that EV competition is a useful exercise in design education that helps develop this ability. Considering the energy problem, we proposed an official competition for small EVs, named “pico-EV Eco Challenge”, as an exercise in engineering design education. In this competition, a small one-person EV using only small rechargeable batteries (7.2 V, 1000 mAh in total) is fabricated and the fabricated EVs run a 60 m circuit. The competition in the years 2021 and 2022 was held on online due to COVID19 pandemic. In this paper, the competition criteria, the flow and the analyses of EVs on 2021 competition are described.
Yoshihiko TAKAHASHI,Takeharu HAYASHI,Yasunori TAKEMURA,Keigo HARA,Satoru YAMAGUCHI 제어로봇시스템학회 2019 제어로봇시스템학회 국제학술대회 논문집 Vol.2019 No.10
Many skills such as machine design, electronic circuit design, microcomputer programming are taught in mechatronics lectures at universities. Parts are given and students assemble the parts according to set examples. However, students cannot develop creativity simply by following fixed examples. In order to foster creativity, it is necessary to make mechatronic systems based on students’ own ideas. Students also need to study production costs, schedule management, team work etc. These skills are important when becoming engineers in companies after graduation. In order that students can use their own ideas, fabricate mechatronic systems, understand production costs, deal with deadlines and develop a team ethos, we have started a compact electric vehicle competition, named “pico-EV Eco Challenge”, and implemented it. In the competition, a one person small electric vehicle using only small rechargeable batteries (7.2V, 1000mAh in total) is fabricated and runs a 60m circuit. In this paper, the history, regulation and management of the competition, examples of participating vehicles, results and benefits of participation, etc. are discussed.
Development of Sintered Ti-30mass%Mo Alloy and Its Corrosion Properties
Sakaguchi, Shigeya,Nakahara, Kenji,Hayashi, Yasunori 대한금속재료학회(대한금속학회) 1999 METALS AND MATERIALS International Vol.5 No.2
Ti-30mass%Mo alloy is characterized by far better corrosion resistance than pure titanium in non-oxidizing acid such as 35% HCl solution. This alloy was newly developed in this work by a powder metallurgical process, because the conventional melting-casting process had difficulties in manufacturing the alloy owing to its heavy gravity segregation. The corrosion behavior of sintered Ti-30Mo alloy was studied by both immersion test and electro-chemical measurement. The corrosion rate of 1.3×10^(-2)[mm/year] was obtained by immersion test in 35% HCl solution, which was 10³ times superior to that of pure titanium. The potentio-dynamic polarization curve of this alloy in 35% HCl solution showed more noble corrosion potential and lower anodic current density than those of pure titanium. The passive film formed on the alloy, in which Mo was enriched by preferential dissolution of titanium, thought to suppress the anodic reaction and improve its corrosion resistance.
Corrosion Protection of Stainless Steel by Double-Layered Oxide Films
Masuda, Masataka,Sakamoto, Hirotoshi,Harada, Kohichiro,Hayashi, Yasunori 한국부식방식학회 2002 Corrosion Science and Technology Vol.31 No.5
Double-layered oxide films of different pH_pzc (pH for point of zero charge) were deposited on stainless steels using RF magnetron sputtering. Anodic polarization measurements in buffer solutions were employed to evaluate the effect of oxide films on the films. The test solution pH was adjusted between the values of pH_pzc of both oxides, so one oxide had positive surface charge and the other had negative surface charge. The corrosion behaviors of coated steels were affected by the stacking order of oxide films. The higher pitting resistance was obtained for the specimens of stacking lower pH_pzc oxide film as an over layer than an under layer. This was explained by the reason that surface charge of the oxide films affected migration of ions in the corrosive solution. We proposed new method of measuring pH_pzc of oxide film with electrochemical AFM (Atomic Force Microscope). The Coulomb force cause by surface fixed charge was detected with AFM in the test solution. This force was varied with the solution pH, and showed minimum value of pH_pzc of oxide film. We showed the oxide double-layer of suitable staking order enhanced remarkably the corrosion resistance of the stainless steels.
Ceramic coatings on 6061 Al alloys by plasma electrolytic oxidation under different AC voltages
Kai Wang,Young Joo Kim,Yasunori Hayashi,이찬규,구본흔 한양대학교 세라믹연구소 2009 Journal of Ceramic Processing Research Vol.10 No.4
Ceramic coatings have been produced on 6061 Al alloy substrates in a weak alkaline-silicon electrolyte under different AC voltage at 60 Hz combined with a 200 V DC voltage for 5 minutes by a plasma electrolytic oxidation process. The surface morphology, composition, structure and microhardness analysis of layers were carried out by an X-ray diffractormetor, optical microscopy, scanning electron microscopy, an energy dispersive X-ray spectrometer and a microhardness tester. Analysis shows that a two-layer structure coating consist of different states of α-Al2O3, β-Al2O3 and γ-Al2O3, where Si concentrates in the hard outer layer, and Cl predominates in the soft internal layer. The influence of deposition AC voltages on the kinetics of coating formation, coating microhardness, the number and size of the discharging channels was investigated.
Interdiffusion in Co/Ta Multilayer Thin Films
Lee, Hui Myeong,Lee, Byeong Seon,Lee, Chan Gyu,Hayashi, Yasunori,Koo, Bon Heun Trans Tech Publications 2005 Defect and Diffusion Forum Vol.237 No.-
<P>We will discuss the stress release phenomena, structural relaxation and interdiffusion processes during annealing. The [Co(4nm)/Ta(4nm)]38 multilayers were prepared by dc magnetron sputtering on Si substrate. The multilayers were annealed at various temperatures (523 - 673K) in vacuum (under 10-5 torr) furnace. The effective interdiffusion coefficients were determined from the slope of the best straight line fit of the first peak intensity versus annealing time [d ln(I(t)/I(0)) /dt] by X-ray diffraction (XRD) low angle measurements. The drastic decrease of the relative intensity in the initial stage shown due to the structural relaxation was excluded in the calculation of effective interdiffusion coefficients. The temperature dependence of interdiffusion in the range of 523 - 673K is described by D = 3.2×10-19 exp(-0.51±0.11 eV/kT) m2s-1.</P>
( Kai Wang ),( Xiao Dong Du ),( Kuk Tae Youn ),( Yasunori Hayashi ),( Chan Gyu Lee ),( Bon Heun Koo ) 대한금속재료학회 ( 구 대한금속학회 ) 2008 METALS AND MATERIALS International Vol.14 No.6
The impact-wear properties of low carbon high manganese alloy steel were tested under three different impact energies (0.7 J, 1.2 J and 1.7 J) using a modified MLD-10 wear tester. SEM inspection of the wear surface and subsurface optical metallographic analysis reveal the impact wear mechanism. Under corrosive conditions we observe a shift from single micro-cutting to impact-flaking, after the appearance of vertical section micro-cracks, while at higher impact energies fatigue corrosion and abrasion are observed.
IrMn 교환결합층을 갖는 스핀밸브막에서의 열적안정성과 자구구조 관찰
이병선,정정규,이찬규,구본흔,야스노리 하야시,Lee Byeong-Seon,Jung Jung-Gyu,Lee Chang-Gyu,Koo Bon-Heun,Hayashi Yasunori 한국재료학회 2004 한국재료학회지 Vol.14 No.2
We have investigated the magnetic domain structure and the thermal stability of magnetotransport properties of IrMn biased spin-valves containing Co, CoFe and NiFe. The magnetic domain structures were imaged using a magneto-optical indicator film(MOIF) technique. To investigate the thermal stability, magnetoresistance(MR) was measured at annealing temperature(TANN) and room temperature($T_{RT}$) followed by the annealing. Domain imaging reveal that the increase of annealing temperature led to changes in the exchange coupling between the two ferromagnet(FM) layers through nonmagnetic layer rather than between FM and antiferromagnet. unlike the NiFe biased IrMn spin valve with large domains, MOIF pictures of Co and CoFe biased IrMn spin valve structures show the formation of many small microdomains. The magnetic structure, as revealed by the domain images, appeared unchanged while the MR dropped dramatically. From the combined giant magnetoresistance(GMR) and MOIF results, it was apparent that the decrease of MR ratio was not related to the spin valve magnetic structure up to about $350^{\circ}C$($T_{RT}$ ).
Co/IrMn 이층막의 자기적 특성과 Co 두께 및 어닐링의 영향
정정규,이찬규,구본흔,이건환,야스노리하야시,Jung, Jung-Gyu,Lee, Chan-Gyu,Koo, Bon-Heun,Lee, Gun-Hwan,Hayashi, Yasunori 한국재료학회 2003 한국재료학회지 Vol.13 No.7
Effects of annealing and thickness of Co layer in Co/IrMn bilayers on the magnetic properties have been investigated. The highest interfacial exchange coupling energy($J_{K}$ = 0.12 erg/$\textrm{cm}^2$) was obtained for 10 nm Co layer thickness. Exchange bias field is inversely proportional to the magnetization, the thickness of the pinned layer, and the grain size of antiferromagnetic layer. Also it is related to the interfacial exchange energy difference, which is expected to depend on the surface roughness. These results almost agree with the random-field model of exchange anisotropy proposed by Malozemoff. Exchange bias field decreased slowly with increasing annealing temperature up to X$300^{\circ}C$. However, exchange bias field increased above $300^{\circ}C$.