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1.
After the remarkable increase of Internet users and broadband Internet subscribers at the end of the 20th century, the size of Korean Internet and e-commerce market steadily increased but the growth rate has been either stagnant or decreased. Trends of Korean Internet and e-commerce market are summarized in this paper the trends on Internet usage are introduced. Trends of online games, blogs and wireless Internet are introduced. The trends of Korean Internet market may have implications for China and Japan. 相似文献
2.
The numerical solution of Dirichlet's problem for a second-orderelliptic operator in divergence form with arbitrary nonlinearitiesin the first- and zero-order terms is considered. The mixedfinite-element method is used. Existence and uniqueness of theapproximation are proved and optimal error estimates in L2 aredemonstrated for the relevant functions. Error estimates arealso derived in Lq, 2q+ 相似文献
3.
High‐Performance Transition Metal Dichalcogenide Photodetectors Enhanced by Self‐Assembled Monolayer Doping
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Dong‐Ho Kang Myung‐Soo Kim Jaewoo Shim Jeaho Jeon Hyung‐Youl Park Woo‐Shik Jung Hyun‐Yong Yu Chang‐Hyun Pang Sungjoo Lee Jin‐Hong Park 《Advanced functional materials》2015,25(27):4219-4227
Most doping research into transition metal dichalcogenides (TMDs) has been mainly focused on the improvement of electronic device performance. Here, the effect of self‐assembled monolayer (SAM)‐based doping on the performance of WSe2‐ and MoS2‐based transistors and photodetectors is investigated. The achieved doping concentrations are ≈1.4 × 1011 for octadecyltrichlorosilane (OTS) p‐doping and ≈1011 for aminopropyltriethoxysilane (APTES) n‐doping (nondegenerate). Using this SAM doping technique, the field‐effect mobility is increased from 32.58 to 168.9 cm2 V?1 s in OTS/WSe2 transistors and from 28.75 to 142.2 cm2 V?1 s in APTES/MoS2 transistors. For the photodetectors, the responsivity is improved by a factor of ≈28.2 (from 517.2 to 1.45 × 104 A W?1) in the OTS/WSe2 devices and by a factor of ≈26.4 (from 219 to 5.75 × 103 A W?1) in the APTES/MoS2 devices. The enhanced photoresponsivity values are much higher than that of the previously reported TMD photodetectors. The detectivity enhancement is ≈26.6‐fold in the OTS/WSe2 devices and ≈24.5‐fold in the APTES/MoS2 devices and is caused by the increased photocurrent and maintained dark current after doping. The optoelectronic performance is also investigated with different optical powers and the air‐exposure times. This doping study performed on TMD devices will play a significant role for optimizing the performance of future TMD‐based electronic/optoelectronic applications. 相似文献
4.
ABSTRACT Superporous hydrogels, hydrogels with pore sizes in the range of 100 μm and larger, were synthesized using N-isopropyl-acrylamide (NIPAM) and acrylamide (AM). The superporous hydrogels were synthesized by crosslinking polymerization of monomers in the presence of gas bubbles. The pores of superporous hydrogels were connected to each other to form open capillary channels, which provided fast response to the changes in the environmental temperature. Upon increase in temperature from 10°C to 65°C, the superporous hydrogel made from a monomer solution of NIPAM:AM = 9:1 shrank from the fully swollen state (volume of 36 cm3) to the fully collapsed state (volume of 6.5 cm3) in 72±14 sec. When the temperature was changed back to 10°C, the superporous hydrogel swelled to 36 cm3 in 78±15 sec. This deswelling-swelling cycle was repeated many times without changes in the thermo-reversible property of the superporous hydrogel. The response time of the superporous hydrogels was thousand times faster than that of conventional hydrogels. The fast response of the superporous hydrogels is due to the rapid uptake or exclusion of water molecules through the extensive capillary channels. Because superporous hydrogels still maintain the open capillary structure even after drying, the dried superporous hydrogels can also swell to the equilibrium swelling state within minutes. These fast responsive hydrogels can find many pharmaceutical and medical applications. 相似文献
5.
H. P. FREUND A. K. GANGULY R. K. PARKER N. R. VANDERPLAATS S. AHN S. Y. PARK 《International Journal of Electronics》2013,100(6):1125-1139
A review of the recent research at the Naval Research Laboratory into gyrotron and ubitron amplifiers is given. In particular, we discuss applications to gyro-klystrons, tapered gyrotrons and gyro-harmonitrons. Ubitron work is devoted to the collective regime of operation and the effects of an axial guide field on the interaction. 相似文献
6.
PARK Kyewon Koh 《中国科学 数学(英文版)》2011,(3):531-538
We introduce the notion of entropy generating sequence for infinite words and define its dimension when it exists. We construct an entropy generating sequence for each symbolic example constructed by Cassaigne such that the dimension of the sequence is the same as its topological entropy dimension. Hence the complexity can be measured via the dimension of an entropy generating sequence. Moreover, we construct a weakly mixing example with subexponential growth rate. 相似文献
7.
Youngchul Cho Nacer-Eddine Zergainoh Sungjoo Yoo Ahmed Amine Jerraya Kiyoung Choi 《Design Automation for Embedded Systems》2007,11(2-3):167-191
In multiprocessor system-on-chip, tasks and communications should be scheduled carefully since their execution order affects
the performance of the entire system. When we implement an MPSoC according to the scheduling result, we may find that the
scheduling result is not correct or timing constraints are not met unless it takes into account the delays of MPSoC architecture.
The unexpected scheduling results are mainly caused from inaccurate communication delays and or runtime scheduler’s overhead.
Due to the big complexity of scheduling problem, most previous work neglects the inter-processor communication, or just assumes
a fixed delay proportional to the communication volume, without taking into consideration subtle effects like the communication
congestion and synchronization delay, which may change dynamically throughout tasks execution. In this paper, we propose an
accurate scheduling model of hardware/software communication architecture to improve timing accuracy by taking into account
the effects of dynamic software synchronization and detailed hardware resource constraints such as communication congestion
and buffer sharing. We also propose a method for runtime scheduler implementation and consider its performance overhead in
scheduling. In particular, we introduce efficient hardware and software scheduler architectures. Furthermore, we address the
issue of centralized implementation versus distributed implementation of the schedulers. We investigate the pros and cons
of the two different scheduler implementations. Through experiments with significant demonstration examples, we show the effectiveness
of the proposed approach. 相似文献
8.
D. H. BOO C. G. PARK 《数学年刊B辑(英文版)》2000,(4)
1. IntroductionGiven a locally compact abelian group G and a multiplier p on G, one can associate tothem the twisted group C*-algebra C*(G, p), which is the universal object for unitary prepresentations of G. C* (Zm, p) is said to be a noncommutative torns of rank m and denotedby A.. The multiplier p determines a subgroup S. of G, called its symmetry group, andthe multiplier p is called totally skew if the symmetry group S. is trivial. And A. is calledcompletely irrational if p is totally… 相似文献
9.
10.
G. S. PARK V. L. GRANATSTEIN J. McADOO C. M. ARMSTRONG A. H. McCURDY S. Y. PARK 《International Journal of Electronics》2013,100(5-6):909-920
A fast feedback loop is employed to reduce conventional phase fluctuation in a klystron and a gyroklystron using both proportional and proportional-integral type feedback circuits. Phase fluctuation of less than one degree is achieved in both the klystron and gyroklystron by using a proportional type feedback circuit; in the klystron, 1.8 degrees of phase jitter is reduced to 0.8 degrees and in the gryroklystron 1.9 degrees to 0.9 degrees. These results agree well with theory. A superior phase jitter reduction ratio of approximately 0.3 is demonstrated in both the klystron and gyroklystron by adding an integrating circuit. 相似文献