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991.
G. Y. Kim J. S. Oh E. H. Choi G. S. Cho S. O. Kang J. Cho 《Materials Science and Engineering: B》2003,100(3):275-279
The change in work function was studied on Indium–tin-oxide (ITO) surface after O-plasma treatment using γ-focused ion beam (γ-FIB). As the surface of ITO experienced more O-plasma treatment, both the surface resistivity and the work function got higher. Auger electron spectroscopy identified the increase of oxygen as well as the decrease of Sn. The rise of work function and surface resistivity is considered to be due to the change in oxygen and Sn on the surface of ITO. 相似文献
992.
Seong-Jin Jang Young-Hyun Jun Soo-In Cho 《Electronics letters》2003,39(2):189-190
A virtual fine delay line (VFDL) using only two ring oscillators and counters can cover a wide frequency operation range clock without adding any additional delay line stage. The proposed ring oscillator can easily make a unit delay as a one-stage inverter. The VFDL achieves fine resolution of less than 60 ps and small circuit area with two clock cycles lock-in time. 相似文献
993.
This letter presents an approximation of the outage probability of the pilot channel that can be used for CDMA cell planning. The approximation can determine system parameters for soft handover in IS‐95‐based cellular CDMA downlink design. Computer simulations show that our analytical results agree with empirical results. 相似文献
994.
Two antimicrobial substances in rice hull were isolated and identified as 4-hydroxybenzoic acid and trans 4-hydroxycinnamic acid by LC-MS, and 1H- and 13C-NMR. An evaluation of 50% inhibition of growth (IC50) revealed that the two substances had different inhibition profiles against various microorganisms. Most of the gram-positive and some gram-negative bacteria were sensitive to trans 4-hydroxycinnamic acid and 4-hydroxybenzoic acid at IC50 concentrations of 100-170 and 160 micrograms/ml, respectively. 相似文献
995.
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
996.
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
997.
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
998.
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
999.
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
1000.
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