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Miniature Ultrasonic and Tactile Sensors for Dexterous Robot
Okuyama, Masanori,Yamashita, Kaoru,Noda, Minoru,Sohgawa, Masayuki,Kanashima, Takeshi,Noma, Haruo The Korean Institute of Electrical and Electronic 2012 Transactions on Electrical and Electronic Material Vol.13 No.5
Miniature ultrasonic and tactile sensors on Si substrate have been proposed, fabricated and characterized to detect objects for a dexterous robot. The ultrasonic sensor consists of piezoelectric PZT thin film on a Pt/Ti/$SiO_2$ and/or Si diaphragm fabricated using a micromachining technique; the ultrasonic sensor detects the piezoelectric voltage as an ultrasonic wave. The sensitivity has been enhanced by improving the device structure, and the resonant frequency in the array sensor has been equalized. Position detection has been carried out by using a sensor array with high sensitivity and uniform resonant frequency. The tactile sensor consists of four or three warped cantilevers which have NiCr or $Si:B^+$ piezoresistive layer for stress detection. Normal and shear stresses can be estimated by calculation using resistance changes of the piezoresitive layers on the cantilevers. Gripping state has been identified by using the tactile sensor which is installed on finger of a robot hand, and friction of objects has been measured by slipping the sensor.
Miniature Ultrasonic and Tactile Sensors for Dexterous Robot
Masanori Okuyama,Kaoru Yamashita,Minoru Noda,Masayuki Sohgawa,Takeshi Kanashima,Haruo Noma 한국전기전자재료학회 2012 Transactions on Electrical and Electronic Material Vol.13 No.5
Miniature ultrasonic and tactile sensors on Si substrate have been proposed, fabricated and characterized to detect objects for a dexterous robot. The ultrasonic sensor consists of piezoelectric PZT thin film on a Pt/Ti/SiO2 and/or Si diaphragm fabricated using a micromachining technique; the ultrasonic sensor detects the piezoelectric voltage as an ultrasonic wave. The sensitivity has been enhanced by improving the device structure, and the resonant frequency in the array sensor has been equalized. Position detection has been carried out by using a sensor array with high sensitivity and uniform resonant frequency. The tactile sensor consists of four or three warped cantilevers which have NiCr or Si:B+ piezoresistive layer for stress detection. Normal and shear stresses can be estimated by calculation using resistance changes of the piezoresitive layers on the cantilevers. Gripping state has been identified by using the tactile sensor which is installed on finger of a robot hand, and friction of objects has been measured by slipping the sensor.
Zhiqiang Wei,Masanori Okuyama,Minoru Noda 한국물리학회 2003 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.42 No.IV
BaTiO3 thin lms with perovskite structure have been prepared on Pt/Ti/SiO2/Si substrate using a combined process of conventional MOD process and a hydrothermal treatment using TiO2 precursor. The BaTiO3 thin lms were crystallized on silicon by hydrothermal treatment at temperature of 140 C. The structure development, stoichiometry, spectroscopic, and dielectric properties of BaTiO3 thin lms have been systematically investigated. X-ray diraction patterns show that well-developed crystallites with perovskite phase have been formed. BaTiO3 thin lm obtained by the mono-treatment process shows (100) preferred orientation, but TiO2 peak still exists which indicated that the reaction is not completed. The stoichiometric BaTiO3 thin lms with a (110) preferred orientation were obtained by the multi-treatment process. AFM observation shows that the roughness of surface is improved with the multi-treatment process.The electric properties of the sample prepared by the multi-treatment process is better than that prepared by the mono-treatment process.
Yoshihide Toyoshima,Masanori Okuyama,Minoru Noda,Mitsue Takahashi 한국물리학회 2003 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.42 No.IV
SrBi2Ta2O9-Bi2SiO5 (SBT-BSO) thin lms have been prepared on Pt/Ti/SiO2/Si substrate by pulsed laser deposition at low temperature, 300 to 450 C . We succeeded in crystallizing SBT at 350 C and P-E hysterisis loops of SBT-BSO thin lm were observed and the curve was almost the same as that of SBT. Binding state of BSO has been investigated by XPS spectra, Raman spectra and AFM. As a result it is conrmed that the binding state of BSO in ceramics is dierent from that in lms prepared by PLD. Moreover we tried to anneal SBT and SBT-BSO thin lms in high pressure O2 atmosphere, and succeeded in improve ferroelectric properties about SBT.
Akira Shibuya,Masanori Okuyama,Minoru Noda 한국물리학회 2003 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.42 No.IV
Bi4Ti3O12-SrBi4Ti4O15 thin lms have been prepared on Pt/Ti/SiO2/Si by pulsed laser deposition (PLD) and their crystalline and electrical properties have been characterized. After oxygen annealing, X-ray diraction (XRD) patterns and grain sizes in atomic force microscopy (AFM) images did not change very much. But P-E hysteresis loop measured at 60 Hz has been improved very much after oxygen annealing. The values of 2Pr and 2Ec were 32 C/cm2 and 190 kV/cm, respectively, after oxygen annealing while 2Pr and 2Ec were 20 C/cm2 and 145 kV/cm, respectively, before oxygen annealing. C-V hysteresis loops shows reasonable results compared with P-E hysteresis loops both before and after oxygen annealing. The relative dielectric constant and dielectric loss were 433 and 0.037, respectively, after oxygen annealing while 595 and 0.071 before post annealing. The dielectric constant of BIT-SBTi lm approaches to that of the ceramics which is around 100 at room temperature after oxygen annealing. This improvement of ferroelectrics is mainly attributed to reduction of oxygen vacancies.p탾
Takeshi Kanashima,Hyun Lee,Masanori Okuyama 한국물리학회 2007 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.51 No.2I
HfO2 thin .lms were prepared by using photoassisted MOCVD with Hf(O-t-C4H9)4 (HTB) and various oxidants. HTB and the oxidizing reagent were supplied alternately. The °at-band shift voltage of the C-V characteristic is about ¡0:3 V in the case of an HfO2 .lm deposited from HTB and H2O2 and is larger than the value for a sample deposited from HTB and H2O. The surface potential (As) of the samples was measured by using photore°ectance spectroscopy. The value of As for the sample deposited from HTB and H2O is a little larger than the value for the sample deposited from HTB and H2O2. This indicates that the amounts of .xed charge in these .lms may be a little large, and that the quality of the .lm is not improved by using H2O2 as an oxidant. On the other hand, the quality was improved by using NH4OH as an oxidant. In this case, the C-V hysteresis is very small and a large accumulation capacitance is observed. The leakage current density is about 1 £ 10¡7 A/cm2 at Vg = 1 V.
Viscous Damping Effect on the CMUT Device in Air
이승목,Bu-sang Cha,Masanori Okuyama 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.58 No.4
Acoustic damping of a capacitive micromachined ultrasonic transducer (CMUT) having a perforated circular membrane in air causes mechanical impedance to the plate vibration. We observed the effect of acoustic damping on the operation of the perforated membrane plate of a CMUT under various geometrical conditions. The damping force of the perforated plate was computed for each area ratio of the acoustic holes (AR) condition, and the results were introduced into calculations of the frequency response function (FRF) using the finite element method (FEM) to take the squeeze-film damping effect into account. The Q factor and the damping ratio of the CMUT under various AR and air-gap height (h) conditions of the device were studied; the acoustic damping effect is discussed in terms of design optimization.
Characterization of Si Interface in FIS Structure by Photoreflectance Spectroscopy
Hirofumi Kanda,Akira Fujimoto,Masanori Okuyama,Masayuki Sohgawa,Takeshi Kanashima,Yoshihide Toyoshima 한국물리학회 2003 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.42 No.IV
SrBi2Ta2O9(SBT) thin lm grown on SiO2/Si by a pulsed laser deposition was evaluated by photore ectance spectroscopy (PRS) which is one of the non-destructive techniques to characterize an interface. The stress of a SiO2/Si interface of ferroelectric-insulator-semiconductor (FIS) structure has been evaluated by using this method. As a result, there is a tensile stress which is larger than that before deposition, and the stress becomes large according to increasing SBT thickness. Moreover, when ferroelectric thin lm is poled, the stress becomes small with increase of the voltage.
Takeshi Kanashima,Koji Ikeda,Masanori Okuyama,Masayuki Sohgawa,Taizo Tada 한국물리학회 2005 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.46 No.1
High-k HfO2 thin lms have been prepared mainly at 400 C in O2 atmosphere by pulsed laser deposition (PLD), and defects in the lm have been characterized by electron spin resonance (ESR). Two ESR peaks are found at g ' 2:003 and 2:006. The g ' 2:006 peak intensity is higher in the sample deposited at target-sample distance of 45 mm than in that deposited at 60 mm. This is because part of the substrate and the lm are exposed to high-energy particles ablated during deposition and are hence damaged. Moreover, the peak at g ' 2:006 is related to the interface state density calculated from the high-frequency C V curve. On the other hand, the peak at g ' 2:003 is related to the thickness of the interfacial layer, and thus may be attributed to defects in the interfacial layer.
Kwi-Young Yun,Masanori Okuyama,Minoru Noda 한국물리학회 2003 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.42 No.IV
BiFeO3 (BFO) thin lms have been prepared on platinized silicon substrates by chemical solution deposition (CSD) and annealed at 600 C for 1 hour under various atmospheres, i.e., O2, Air and N2. Eects of annealing atmospheres on the crystallization and electrical properties of BFO lms were investigated. Crystallization behavior and electrical properties of BFO lms depend on the oxygen partial pressure of the annealing atmosphere. The BFO thin lm annealed in N2 atmosphere showed a good crystallinity. The surface roughness of the BFO lm decreased with lowering oxygen partial pressure of the annealing atmosphere. Low leakage current density and P-E hysteresis were found only in the BFO lm annealed at 600 C under N2 atmosphere. Leakage current density, polarization (at zero electric eld) and electric eld (at zero polarization) of the BFO lm annealed at 600 C under N2 are 510..7A/cm2 at 1 V, 0.2 C/cm2 and 15 kV/cm, respectively.