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11.
Sun-Hwa Yeon Jeasung Park Youngjune Park Sukjeong Choi Kyuchul Shin Jiwoong Seol Minjun Cha Huen Lee 《Korean Journal of Chemical Engineering》2008,25(1):154-157
Clathrate compounds are crystalline materials formed by a physical interaction between host and relatively light guest molecules.
Various types of nano-sized cages surrounded by host frameworks exist in the highly unique crystalline structures and free
guest molecules are entrapped in an open host-guest network. Recently, we reported two peculiar phenomena, swapping and tuning,
naturally occurring in the hydrate cages. Helium, one of the smallest light guest molecules, must be the challengeable material
in the sense of physics and moreover possesses versatile applications in the field of superconductivity technology and thermonuclear
industry. In this regard, we attempted for the first time to synthesize helium hydrates at moderate temperature and pressure
conditions. According to inclusion phenomena, helium itself normally cannot form clathrate hydrates due to being too small
molecularly without the help of hydrate former molecules (sI, sII, and sH formers). In this study, the hydrate equilibria
of the binary clathrate hydrate containing tetrahydrofuran, helium, and water were determined at 2, 3, 5.56 THF mol%. Direct
volumetric measurements were also carried out to confirm the exact amount of helium captured in the hydrate cages. Finally,
the crystalline structure of the formed mixed hydrates was identified by powder X-ray diffraction, resulting in structure
II. 相似文献
12.
R. M. Hwang K. C. Cha 《The International Journal of Advanced Manufacturing Technology》2008,37(11-12):1093-1104
Learning and prediction capability of the backpropagation neural network (BPNN) have been used to build the prediction model for the structural stability of a surface grinder. The Lagrange energy method is applied to derive the dynamic equation of the lumped parameter model of the surface grinder. The major factors influencing the structural stability of the system can be determined after the ratio of kinetic energy of the sub-structure and the ratio of potential energy of the sub-structure interface are obtained. An orthogonal rotatable central composite design is adopted to dispose the treatment combinations of the major factors. The BPNN model is constructed by the treatment combinations of the training patterns and verified by the treatment combinations of the test patterns. In this paper, a 3-layer BPNN model with a 10-neuron hidden layer which converged after 4,072 learning cycles is selected to predict the structural stability of a surface grinder within the planned ranges. The percentage residuals of both training patterns and test patterns are all within 3.41%, thus the prediction accuracy of the BPNN model is excellent so that the engineering demands are well satisfied. 相似文献
13.
TheCubooctahedronShape──ASuboptimalCellShapefor3-DimensionalCellularSystemChaGuangming;LiZhengmao;LuFan(UniversityofElectroni... 相似文献
14.
Long-term exposure to cocaine can cause persistent behavioral changes and alterations in neuronal function. One cocaine-regulated mRNA in the rat brain is the beta-1 subunit of the Na+/K(+)-ATPase pump. We examined both Na+/K(+)-ATPase function and expression after cocaine treatment of pheochromocytoma cells. One-hour exposure to cocaine did not alter Na+/K(+)-ATPase activity, as measured by the ouabain-sensitive component of rubidium uptake. Four days of cocaine resulted in an approximately 30% decrease in Na+/K(+)-ATPase activity. Western blot analyses demonstrated an approximately 25% decrease in levels of the beta-1 isoform, without changes in pump total alpha subunit levels. Treatment with dopamine type 1 or type 2 receptor agonists for the same period did not affect Na+/K(+)-ATPase activity. The serotonin-selective reuptake inhibitor paroxetine caused an approximately 45% decrease in rubidium uptake after 4 days, whereas pump function was not altered after treatment with either the dopamine-selective reuptake blocker nomifensine or the norepinephrine-selective reuptake blocker desipramine. Chronic treatment with both cocaine and LY 278,584, a serotonin type 3 receptor antagonist, did not replicate the cocaine-associated decrease in pump function. Long-term cocaine exposure regulates expression and function of the Na+/K(+)-ATPase pump in neuronal-like cells; this regulation is mediated in part via the serotonin type 3 receptor. Similar Na+/K(+)-ATPase pump regulation in vivo may selectively alter neuronal function in the mammalian brain. 相似文献
15.
16.
Jung Nam Bae Jin Young Kim Geon Kim Yong Tae Lee Jae Sang Cha 《Multimedia Tools and Applications》2012,57(2):359-372
Recently, watermarking based data transmission techniques using terrestrial digital TV signal have been proposed since they
are also cost-free and can overcome the limitations of GPS. However, in the previous watermarking based methods, the detection
accuracy is low and additional data rate is too low. Thus, we propose the throughput enhancement method by employing the TZCD-MBOK
watermarking technique in T-DMB system. By applying the proposed scheme to T-DMB, it allows additional data transmission for
disaster broadcasting and improves efficiency of data transmission in shadow region and indoor to mobile environment through
watermarking spread code. From the simulation results, we confirm the proposed watermarking scheme affected on the existing
T-DMB signal. Moreover, it was also confirmed that the system capacity increases as the power of additional watermarking signal
rose. The results of the paper can be applied to wireless multimedia digital broadcasting systems. 相似文献
17.
The shear strength and aging characteristics of 63Sn–37Pb solder bumps were characterized with variation in solder ball and
UBM pad sizes. The shear strength increased with shorter effective crack size,a
effs
which was determined with the solder ball and pad sizes. The shear strength of the solder bumps on Au/Ni/Cu and Ni/Cu did
not change significantly with reflow time. Substantial decrease in the shear strength occurred for the solder bumps formed
on Au/Ni/Cu with aging treatment, and the shear strength after aging was also related to the bump shape which was determined
with the solder ball and pad sizes. 相似文献
18.
Pil-Ryung Cha Ho-Seok Nam Dae-Yeong Jeon Jong-Kyu Yoon 《Metals and Materials International》2002,8(1):119-127
This study presents a simple and robust algorithm for the optimal design of the system with coupled complex transport phenomena:
the transport phenomena comprise fluid flow, heat and mass transfer. The (1+1)-Evolution Strategy method is adopted as the optimization method. In order to analyze the transport phenomena in the complex geometry generated
during the optimization procedure, thefinite volume method with a boundary fitted curvilinear coordinate system is used. To confirm the validity of the present method, the optimal
design for the inner shape of the simplified two-dimensionalSubmerged Entry Nozzle in the continuous slab caster is conducted. It is shown that the resulting design of the nozzle is consistent with the purpose
and constraints of the design. 相似文献
19.
Gil-Young Song Youngjoon Cheon Kihwang Lee Heuiseok Lim Kyung-Yong Chung Hae-Chang Rim 《Personal and Ubiquitous Computing》2014,18(6):1387-1403
As various forms of social media are spreading, we often witness that an idea of an individual user drives macroscopic changes. From the perspectives of product development and marketing, the opinions left by potential consumers in online social network can generate big ripple effects. This study analyzes the user opinions in online space to grasp preferences toward various products psychologically categorized by users. We also suggest an aspect of the market mentally configured by users using network modeling while following the framework of economic sociology. Existing analyses on online market place are mainly dealing with structural issues such as inter-actor relationships and status measurement. This study, however, analyzes complex preferences regarding diverse products and brands and derives a new model for inter-market connections. We expect that our study will provide important consequences on digital marketing and community design of corporations planning word of mouth effect in online space. 相似文献
20.
Chang‐Gyu Kim Sung‐Hoon Joo Cheol Hong Cheon Mi‐Yun Jeong Soon‐Wook Cha Byung‐Hee Sohn Jung‐Il Jin 《应用聚合物科学杂志》2006,100(1):307-317
Three new soluble polyconjugated polymers, all of which emitted blue light in photoluminescence and electroluminescence, were synthesized, and their luminescence properties were studied. The polymers were poly{1,1′‐biphenyl‐4,4′‐diyl‐[1‐(4‐t‐butylphenyl)]vinylene}, poly((9,9‐dioctylfluorene‐2,7‐diyl)‐alt‐{1,4‐phenylene‐[1‐(4‐t‐butylphenyl)vinylene‐1,4‐phenylene]}) [P(DOF‐PVP)], and poly([N‐(2‐ethyl) hexylcarbazole‐3,6‐diyl]‐alt‐{1,4‐phenylene‐[1‐(4‐t‐butylphenyl)]vinylene‐1,4‐phenylene}). The last two polymers had alternating sequences of the two structural units. Among the three polymers, P(DOF‐PVP) performed best in the light‐emitting diode devices of indium–tin oxide/poly(ethylenedioxythiophene) doped with poly(styrene sulfonate) (30 nm)/polymer (150 nm)/Li:Al (100 nm). This might have been correlated with the balance in and magnitude of the mobility of the charge carriers, that is, positive holes and electrons, and also the electronic structure, that is, highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) levels, of the polymers. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 307–317, 2006 相似文献