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Developing a New Carrier System with Throwing and Catching Robot
Yutaka Sameshima,Ryuichi Oguro 제어로봇시스템학회 2008 제어로봇시스템학회 국제학술대회 논문집 Vol.2008 No.10
Control of an object-throwing and catching robot is examined in this paper. We develop a new carrier system which uses two robots, thrower robot and catcher robot. In order to realize this system, we need to know problems which could happen in throwing and catching motion of these robots. Therefore, we have to produce a preliminary experiment system by a linear slider which has two sliders, thrower slider and catcher slider. In this experiment, the thrower slider throws a ball by inertial force, and the catcher slider moves automatically to point of fall of the ball with information about velocity of the thrower side. The experiment has following results. First, points of the thrown ball differ a little from each result in spite of the same condition. Second, we can find it is important to improve the accuracy of throwing a ball to a target position. In this paper, we show the structure of the prelimin ary system, and the verified problems about this system.
Enhancement of strength of SiC by heat-treatment in air
Naoki Matsunaga,Soichiro Sameshima,Kyosuke Nakahama,Yoshihiro Hirata 한양대학교 세라믹연구소 2009 Journal of Ceramic Processing Research Vol.10 No.3
An 800 nm-SiC powder (75 vol%) was mixed with a 30 nm-SiC powder (25 vol%) in a 0.3 mol/l Y(NO3)3 solution containing an Al2O3 powder of median size 200 nm at pH 5 to distribute homogeneously the sintering additives (Al2O3+Y3+ ion) around the SiC particles. Polyacrylic acid of 1.0 mg/m2-SiC surface was added as a dispersant. This suspension was consolidated by casting in a gypsum mold. The green compacts of 43% theoretical density were hot-pressed to a relative density 98.1 ± 2.1% at 1950℃ in an Ar atmosphere. The strength of the dense SiC was in the range from 560 to 1080MPa (average strength 810MPa, Weibull modulus 5.9). The as-hot-pressed SiC was heat-treated in air for 24 h at 1100˚ and 1300 ℃. The heat-treatment at 1100℃ improved the strength in the low fracture probability range (< 40%) and narrowed the strength range (700-1250MPa, average strength 820 MPa). On the other hand, the heat-treatment at 1300℃ shifted greatly the strengths in all the fracture probability range to higher values (750-1180 MPa, average strength 960MPa). The Weibull modulus was also increased to 8.3. The above results may be related to the decrease of size and shape factor of fracture origins near the SiC surfaces by the formation of SiO2. A compressive stress may be also produced on the surface region of the dense SiC which contributes to the increased strength. An 800 nm-SiC powder (75 vol%) was mixed with a 30 nm-SiC powder (25 vol%) in a 0.3 mol/l Y(NO3)3 solution containing an Al2O3 powder of median size 200 nm at pH 5 to distribute homogeneously the sintering additives (Al2O3+Y3+ ion) around the SiC particles. Polyacrylic acid of 1.0 mg/m2-SiC surface was added as a dispersant. This suspension was consolidated by casting in a gypsum mold. The green compacts of 43% theoretical density were hot-pressed to a relative density 98.1 ± 2.1% at 1950℃ in an Ar atmosphere. The strength of the dense SiC was in the range from 560 to 1080MPa (average strength 810MPa, Weibull modulus 5.9). The as-hot-pressed SiC was heat-treated in air for 24 h at 1100˚ and 1300 ℃. The heat-treatment at 1100℃ improved the strength in the low fracture probability range (< 40%) and narrowed the strength range (700-1250MPa, average strength 820 MPa). On the other hand, the heat-treatment at 1300℃ shifted greatly the strengths in all the fracture probability range to higher values (750-1180 MPa, average strength 960MPa). The Weibull modulus was also increased to 8.3. The above results may be related to the decrease of size and shape factor of fracture origins near the SiC surfaces by the formation of SiO2. A compressive stress may be also produced on the surface region of the dense SiC which contributes to the increased strength.
Choroidal Venous Pulsations at an Arterio-venous Crossing in Polypoidal Choroidal Vasculopathy
Akiko Okubo,Munefumi Sameshima,Taiji Sakamoto 대한안과학회 2013 Korean Journal of Ophthalmology Vol.27 No.5
It has been reported that pulsations in abnormal vessels are observed on indocyanine green (ICG)angiography in half of patients with polypoidal choroidal vasculopathy (PCV), although the mechanism of the pulsation is unknown. In this study, we report a case of PCV showing venous pulsations at an arteriovenous (A-V) crossing, and discuss a possible mechanism of polypoidal vessel formation and pulsations in PCV. A 66-year-old female presented with a reddish-orange elevated lesion and serous retinal detachment in the macula of her left eye, and was diagnosed as PCV. She was treated with photodynamic therapy (PDT),and followed-up through routine examinations, including ICG angiography. ICG angiography at presentation showed a branching vascular network and choroidal venules with dye leakage (polypoidal vessels) in the left eye. Pulsations, supposedly of venous origin, were observed at an A-V crossing in the abnormal vessels. Within 3 months after PDT, the polypoidal vessel ceased to leak and the pulsations vanished. The reddish-orange lesion gradually decreased in size with complete disappearance of retinal detachment. This study suggests that an unusual compression at an A-V crossing may make a venule polypoidal, and fluctuations of blood flow and pressure in the venule may cause pulsatile movements of the vessel wall.
Yoshihiro Hirata,Soichiro Sameshima,Keisuke Higashinakagawa 한양대학교 세라믹연구소 2004 Journal of Ceramic Processing Research Vol.5 No.1
This paper reports the preparation, microstructures and electrical properties of a Ni (55 vol%)/Sm-doped ceria cermet. A nickel powder of median size 14 μm or a NiO powder of median size 2.5 μm was mixed with Sm-doped ceria (SDC) powder(median size 0.87 μm) with a composition of Ce0.8Sm0.2O1.9, which was produced by the calcination of an oxalate solid solution (Ce0.8Sm0.2)2(C2O4)3 at 600캜. The mixtures of Ni/SDC (sample A) and NiO/SDC (sample B) were sintered at 1300 캜 in air to a relative density of 58.6% and 97.3%, respectively. During the sintering of the cermet, the Ni powder was oxidized to NiO in sample A. The NiO component in the as-sintered cermet was reduced to Ni in a H2-H2O atmosphere of an oxygen partial pressure ~10.20 atm at 700캜. Both the cermets showed a high stability of high electronic conduction to 100 h of heating at 700캜 in a low oxygen partial pressure atmosphere. Sample A with large Ni particles was too brittle to handle after the heating. Sintering of the fine Ni grains in sample B proceeded at 700C
Interaction between ultrafine ceria particles and glycine
Yoshihiro Hirata,Hisanori Shimazu,Hideyuki Takahashi,Soichiro Sameshima 한양대학교 세라믹연구소 2004 Journal of Ceramic Processing Research Vol.5 No.1
An ultrafine ceria powder of 15 nm equivalent spherical particle diameter was dispersed at 2 vol% solid in aqueous solutions with and without glycine (H2NCH2COOH) of 0.05-5.0 mass% against ceria. The addition of glycine increased the zeta potential of the ceria toward positive values in acidic suspensions. The phase separation of ceria suspensions due to the decreased repulsive energy with decreasing particle size, was suppressed by the steric stabilization effect of the adsorbed glycine. No significant influence of the glycine addition on the zeta potential and phase separation of the basic suspension was measured.