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Spike-compensated Low-Voltage Unity-Gain-Reset Switched-Capacitor Cyclic Digital-to-Analog Converter
Kenji OHNO,HirokiMATSUMOTO,Kenji MURAO 대한전자공학회 2008 ITC-CSCC :International Technical Conference on Ci Vol.2008 No.7
As the chip integration advances toward the CMOS VLSI integrated systems, on-chip Digital-to-Analog Converter (DAC) becomes more important building blocks. Key technologies in DAC is fabrication at low-cost and operation on high-performance. Highresolution and Low-Voltage DAC is required in many fields. Their advantage extends to mixed-signal systems where both frequency higher, the device shrinks into deep sub-micrometer. However the shrinking device dimensions also imply proportional scalling of power supply voltage. Advantages of Alogorithmic DAC using Switched-Capacitor (SC) are suitable to the above requirement. SC are small chip area, low consumption of electoric power, and compatibility to MOS IC. To operate under low supply voltage, terminal of NMOS analog switch should connect to ground or virtual ground. However, major performance of conventional algolithmic DAC is limited by offset voltage and spike. In this paper, it shows a Low-Voltage SC cyclic DAC. It is proposed which consists of a switch, capacitor, MOSFET and op-amp. Circuit operation is evaluated on SIMetrix.
Kenji OHNO,Hiroki MATSUMOTO,Kenji MURAO 대한전자공학회 2009 ITC-CSCC :International Technical Conference on Ci Vol.2009 No.7
As the chip integration advances toward the CMOS VLSI integrated systems, on-chip Digital-to-Analog Converter (DAC) becomes more important building blocks. Key technologies in DAC is fabrication at low-cost and operation on high-performance. Highresolution and Low-Voltage DAC is required in many fields. Their advantage extends to mixed-signal systems where both frequency higher, the device shrinks into deep sub-micrometer. However the shrinking device dimensions also imply proportional scalling of power supply voltage. Advantages of alogorithmic DAC using Switched-Capacitor (SC) are suitable to the above requirement. SC operates on small chip area, low consumption of electoric power, and is compatible to MOS IC. To operate under low supply voltage, terminal of NMOS analog switch should connect to ground or virtual ground.[1] However, major performance of conventional algolithmic DAC is limited by offset voltage and spike.[2] In this paper, they shows two Low-Voltage SC cyclic DACs. They are proposed which consists of a switch, capacitor, MOSFET and operational amplifier (op-amp). Circuit operation is evaluated on SIMetrix.
Electroluminescence from n-Zn(Mg,Cd)O/ p-4H-SiC:Al Heterojunctions
Kenji Yamamoto,Toshiya Ohashi,Atsushi Nakamura,Temmyo Jiro 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.5
Electroluminescence (EL) from n-Mg0:18Zn0:82O/ n-Zn(Mg,Cd)O/ p-4H-SiC:Al heterojunction diodes fabricated by using remote-plasma-enhanced metal-organic chemical-vapor deposition was measured to investigate some recombination processes of hole injection by changing the bandgap of n-Zn(Mg,Cd)O. EL emissions from the heterojunction utilizing n-Zn1-xCdxO (x > 0.07) were observed to coincide with the photoluminescence (PL) emission energy of the corresponding alloy content due to hole injection from the p-4H-SiC:Al to the n-Zn1-xCdxO layer in the type-I het-erojunctions. However, broad EL emissions from the type-II heterojunctions utilizing n-ZnO and n-Mg0:12Zn0:88O were observed at around 2.8 eV. These broad ELs were caused by the recombination of carriers in p-4H-SiC:Al due to electron injection from n-Zn(Mg,Cd)O to p-4H-SiC:Al and by the recombination of spatially separated carriers at the heterointerface.
Heteroclinic Turbulence in the Lotka-Volterra Reaction Diffusion Equation
Kenji Orihashi,Yoji Aizawa 한국물리학회 2007 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.50 No.1I
Heteroclinic turbulence in the Lotka-Volterra reaction diusion equation is studied numerically and theoretically, and the statistical feature is analyzed precisely in reference to the onset mechanism of the turbulence. First, the bifurcation diagram is demonstrated in detail, and a variety of attractors are discussed. It is emphasized that the diversity of the attractor enhances when the system size increases. Next, the transition from a regular attractor to a turbulent one is characterized by a correlation function, as well as by the Lyapunov exponent, where one can observe the scaling laws clearly for the correlation length and the maximum Lyapunov exponent.m
Comparative study among Asian Oribatid Fauna. -Is oribatid fauna rich in tropical zone?-
Kenji Fukuyama 한국응용곤충학회 2008 한국응용곤충학회 학술대회논문집 Vol.2008 No.10
It is widely believed that diversity of soil animals are poorer in the tropical zone than in the temperate zone. Is this right? Then, I compared Asian oribatid faunae of the following localities: a tropical lowland rain forest in Pasoh Forest Reserve (Peninsular Malaysia), a subtropical forest in Yunnan Province (China), warm temperate forest in Chiba, a cool temperate forest in Sapporo (Japan), and in a taiga in arctic zone in Siberia (Russia). Samplings in a primary forest and in a 40-year secondary forest, which were 2 ha each and adjacent to each other, showed about 100 oribatid species there. Total species number was estimated at 135 to 150 with Jackknife method. This shows that the species diversity of oribatids are rich in tropics as compared with that in the temperate Japan. Oribatid species richness was even lower in Siberia (Yakutsk) than in Japan. These indicate that oribatid diversity in tropics is higher than in other areas of higher latitudes. Analyses based on Motomura's geometric series rule showed that the inclination became steeper with latitude, also suggesting that a high species diversity in the tropics. Although the number of families did not change greatly with latitude, a DCA analysis showed that composition of families was related with latitude. It was shown that a low latitude area has many winged oribatid mites, such as Haplozetidae, Protoribatidae, and Galumnidae, with many primitive groups in a high latitude area, such as Brachychthoniidae and Hypochthoniidae.
A Proposal for Generating Good Assembly Sequences by Tournament Tree
Kenji Tsuboi,Toshiyuki Matsumoto,Shinji Shinoda,Akira Niwa 대한산업공학회 2011 Industrial Engineeering & Management Systems Vol.10 No.2
In seeking further efficiency in production preparation, it is common to examine assembly sequences using digital manufacturing. The assembly sequences affect the product evaluation, so it is necessary to test several assembly sequences before actual production. However, because selection and testing of assembly sequences depends on the operator"s personal experience and intuition, only a small number of assembly sequences are actually tested. Nevertheless, there is a systematic method for generating assembly sequences using a contact-related figure. However, the larger the number of parts, the larger the number of assembly sequences geometric becomes. The purpose of this study is to establish a systematic method of generating efficient assembly sequences regardless of the number of parts. To generate such assembly sequences selectively, a "Tournament Tree," which shows the structure of an assembly sequence, is formulated. Applying the method to assembly sequences of a water valve, good assembly sequences with the same structure as the Tournament Tree are identified. The structure of such a Tournament Tree tends to have fewer steps than the others. As a test, the structure is then applied for a drum cartridge with 38 parts. In all the assembly sequences generated from the contact-related figures, the best assembly sequence is generated by using the Tournament Tree.
Kenji Naruse,Hong Rye Kim,Young Min Shin,Suk Min Chang,,Hye Ran Lee,Vaishali Tarte,Yan Shi Quan,Beak Chul Kim,Tae Young Park,Su Min Choi,Chang Sik Park,Dong Il Jin 사단법인 한국동물생명공학회 2006 Reproductive & developmental biology Vol.30 No.1
Electrical treatment has been widely used for porcine oocytes activation. However, developmental rates following electrical activation of porcine oocytes is relatively inefficient compared to other domestic animals. To investigate the effects of porcine oocytes on combined activation by both chemical and electrical treatment, in-vitro matured oocytes were activated by combined cycloheximide and electrical pulses treatment. Cumulus-free oocytes were exposed with NCSU-23 medium containing cycloheximide (10 μg/ml) for 0, 5, 10, 20, 30 min and then activated by electrical pulse treatment and cultured in PZM-3 for 8 days. Also effects of exposure to 6.25 μM calcium ionophore for 2 min for cumulus-free oocytes were tested. The percentage of blastocyst formation in 10 min exposure to 10 μg/ml cycloheximide and electrical pulse treatment was significantly increased (P<0.05) than in the control group. And exposure to 6.25 μM calcium ionophore for 2 min with 10 μg/ml cycloheximide for 10min and electrical pulse treatment significantly increased (P<0.05) the percentage of blastocyst developmental rates than the control group. In conclusion, activation by combined cycloheximide and electrical stimulation treatment promoted the subsequent development of porcine oocytes and improved the subsequence blastocyst development.