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951.
Seung-Moon Yoo Ejaz Haq Seung-Hoon Lee Yun-Ho Choi Soo-In Cho Nam-Soo Kang Daeje Chin 《Solid-State Circuits, IEEE Journal of》1993,28(4):499-503
Wide-voltage-range DRAMs with extended data retention are desirable for battery-operated or portable computers and consumer devices. The techniques required to obtain wide operation, functionality, and performance of standard DRAMs from 1.8 V (two NiCd or alkaline batteries) to 3.6 V (upper end of LVTTL standard) are described. Specific techniques shown are: (1) a low-power and low-voltage reference generator for detecting V CC level; (2) compensation of DC generators, V BB and V PP, for obtaining high speed at reduced voltages; (3) a static word-line driver and latch-isolation sense amplifier for reducing operating current; and (4) a programmable V CC variable self-refresh scheme for obtaining maximum data retention time over a full operating range. A sub-50-ns access time is obtained for a 16 M DRAM (2 M×8) by simulation 相似文献
952.
Intracytoplasmic sperm injection (ICSI) and partial zona dissection followed by insemination (PZD-I) were used to establish a microinjection system in cynomolgus monkeys (Macaca fascicularis), which are potential models for human reproduction. Two experimental systems were studied, in which either hamster oocytes or cynomolgus monkey oocytes were used as the vehicle. When hamster oocytes were used, 66 out of 81 ICSI-treated oocytes (82%) showed sperm head swelling or pronucleus formation. Following PZD-I of hamster oocytes the rates of spermatozoa penetration (85/114; 75%) and fertilization (71/114; 62%) were relatively high. When cynomolgus monkey oocytes were used, 19 out of 31 (61%) were fertilized by ICSI with cynomolgus monkey spermatozoa and, subsequently, two embryos (7%) developed to the morula stage. In total, 94% (15/16) of the PZD-I treated oocytes were penetrated by spermatozoa and 63% (10/16) were fertilized. These results demonstrate that both micromanipulation techniques can be used in assisted fertilization with cynomolgus monkeys. 相似文献
953.
This paper presents a method of classifying solder joints on printed-circuit boards (PCB), using a neural-network approach. Inherently, the surface of the solder joints is curved, tiny and specularly reflective; it induces a difficulty of taking good images of the solder joints. The shapes of the solder joints tend to vary greatly with soldering conditions; solder joints, even when classified into the same soldering quality, have very different shapes. Furthermore, the position of the joints is not consistent within a registered solder pad on the PCB. Due to these aspects, it has been difficult to determine the visual features and classification criteria for automatic solder-joint inspection. In this research, the solder joints, imaged by using a circular, tiered illumination system of three colored lamps, are represented as red, green and blue colored patterns, showing their surface-slopes. Cross-correlation and auto-correlation of the colored patterns are used to classify the 3D shapes of the solder joints by their soldering qualities. To achieve this, a neural network is proposed, based on a functional link net, with two processing modules. The first preprocessing module is designed to implement the calculation of the correlations in functional terms. The subsequent, trainable module classifies the solder joints, based upon the capability learned from a human supervisor. The practical feasibility of the proposed method is demonstrated by testing numerous commercially manufactured PCBs. 相似文献
954.
Kyu - Kab Cho 《Computers & Industrial Engineering》1996,31(3-4):543-549
This article describes a general overview of industry development, present status and future perspectives of manufacturing technology in Korea. The Advanced Manufacturing System project, which is one of the national R&D projects in manufacturing technology, is introduced. The problems for the future development of manufacturing technology in Korea is discussed. 相似文献
955.
Photoaffinity labeling with [gamma-32P]8N3GTP (8-azidoguanosine triphosphate) was used to identify the guanine binding peptides of the GTT binding site within two types of glutamate dehydrogenase isoproteins (GDH I and GDH II) isolated from bovine brain. 8N3GTP, without photolysis, mimicked the inhibitory properties of GTP on GDH I and GDH II activities. Saturation of photoinsertion of GDH isoproteins revealed an apparent Kd of 8 microM (GDH I) and 24 microM (GDH II) for [gamma-32P]8N3GTP. Ion exchange and reversed-phase high-performance liquid chromatography (HPLC) were used to isolate photolabel-containing peptides generated with trypsin. This identified a portion of the guanine binding domain within the GTP binding site is the region containing the sequence I-S-G-A-S-E-X-D-I-V-H-S-A-L-A-Y-T-M E-R (GDH I) and I-S-G-A-S-E-X-D-I-V-H-S-G-L-A-Y-T-M-E-R (GDH II). The symbol X indicates a position for which no phenylthiohydantoin-amino acid could be assigned. The missing residue, however, can be designated as a photolabeled lysine since the sequences including the lysine residue in question have a complete identity with those of the other GDH species known. Also, trypsin was unable to cleave the photolabeled peptide at this site. Photolabeling of these peptides was prevented by the presence of GTP during photolysis, while other nucleotides could not reduce the amount of photoinsertion as effectively as GTP. These results demonstrate selectivity of the photoprobe for the GTP binding site and suggest that the peptide identified using the photoprobe is located in the GTP binding domain of the brain GDH isoproteins. 相似文献
956.
K. Sambasiva Rao T. N. V. K. V. Prasad N. Vallisnath Joon-Hyung Lee Sang-Hee Cho 《Ferroelectrics Letters Section》2003,30(1):25-39
Present communication describes the preparation and the influence of Pr 2 O 3 and Nd 2 O 3 on structure, ferroelectric, dielectric, pyroelectric and resistivity properties of (Ba 1-x Sr x ) 2 NaNb 5 O 15 [BSNN] compositions at and around x = 0.6, MPB region. Substitution of Pr 2 O 3 /Nd 2 O 3 decrease the cell volume and Curie temperature and enhance the room temperature dielectric constant. The room temperature pyroelectric coefficients are observed to be in the order of 10-9 C/cm 2 °C. Higher figure of merit FM RV , FM RN and FM RI values of the order 10-14 CM/J, 10-12 CM/J and 10-11 CM/J respectively are observed in both Pr/Nd:BSNN compositions. Resistivity studies revealed a PTCR behavior. 相似文献
957.
Adaptive random access and resource allocation scheme based on traffic load in HiperLAN type2 system
Hyun-Ho Choi Gyung-Ho Hwang Dong-Ho Cho 《Communications Letters, IEEE》2003,7(4):192-194
The MAC protocol of HiperLAN type2 is based on TDMA/TDD and provides access control and resource allocation schemes. We propose a scheme that provides adaptive random access and efficient resource allocation according to the traffic load for HiperLAN type2, by using access probability. The analysis and simulation results show that the proposed scheme performs better than the conventional scheme and supports priority services easily. 相似文献
958.
A novel frequency-hopping spread-spectrum multiple-access network using M-ary orthogonal Walsh sequence keying 总被引:1,自引:0,他引:1
Joonyoung Cho Youhan Kim Kyungwhoon Cheun 《Communications, IEEE Transactions on》2003,51(11):1885-1896
A novel frequency-hop spread-spectrum multiple-access network employing M-ary orthogonal Walsh sequence keying with noncoherent demodulation is proposed. The transmitted Walsh sequence is overlaid by a user-specific pseudonoise sequence to reduce the effect of multiple-access hits. Two Gaussian approximations for the multiple-access interference from both the dehopped slot and its neighboring slots are developed and are used to analyze the performance of the proposed network for synchronous and asynchronous hopping under nonfading and Rayleigh fading channels. The effect of imperfect hop timing synchronization at the receiver is also analyzed. It is shown that the proposed network offers significantly improved network throughput compared to networks based on traditional M-ary frequency-shift keying modulation. 相似文献
959.
Kyoung Hwan Yeo Chang Woo Oh Sung Min Kim Min Sang Kim Chang Sub Lee Sung Young Lee Sang Yeon Han Eun Jung Yoon Hye Jin Cho Doo Youl Lee Byung Moon Yoon Hwa Sung Rhee Byung Chan Lee Jeong Dong Choe Ilsub Chung Donggun Park Kinam Kim 《Electron Device Letters, IEEE》2004,25(6):387-389
Highly manufacturable partially insulated field-effect transistors (PiFETs) were fabricated by using Si-SiGe epitaxial growth and selective SiGe etch process. Owing to these technologies, pseudo-silicon-on-insulator (SOI) structures, partially insulating oxide (PiOX) under source/drain (PUSD) and PiOX under channel (PUC), could be easily realized with excellent structural and process advantages. We are demonstrating their preliminary characteristics and properties. Especially, in the PUSD PiFET, junction capacitance, leakage current, and DIBL in bulk devices could be reduced and the floating body problem in SOI devices was also cleared without any area penalty. Thus, this PiFET structure can be a promising candidate for the future DRAM cell transistor. 相似文献
960.
Young-Moon Kim Ki-Pyo You Ji-Eun Cho Dong-Pyo Hong 《Journal of Mechanical Science and Technology》2006,20(6):795-805
Tuned Liquid damper and Tuned Liquid Column are kind of passive mechanical damper which relies on the sloshing of liquid in
a rigid tank for suppressing structural vibrations. TLD and TLCD are attributable to several potential advantages —low costs;
easy to install in existing structures; effective even for small-amplitude vibrations. In this paper, the shaking table experiments
were conducted to investigate the characteristics of water sloshing motion in TLD (rectangular, circular) and TLCD. The parameter
obtained from the experiments were wave height, base shear force and energy dissipation. The shaking table experiments show
that the liquid sloshing relies on amplitude of shaking table and frequency of tank. The TLCD was more effective control vibration
than TLD. 相似文献