• Journal of the Computational Structural Engineering Institute of Korea
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• v.25 no.5
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• pp.447-454
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• 2012

Considering that the weight of a hollow slab system is not increased with an incremental increase in its thickness, and that the flexural stiffness of a hollow slab is not significantly lower than that of a general slab, there has been a growing need for hollow slab system, because long span structures are in great demand. In a long span structure, the problem of vibration of floor slabs frequently occurs, and the dynamic characteristics of a hollow slab system are quite different from the conventional floor system. It is required to investigate the safety and the serviceability of hollow slab. Therefore, there exists a necessity for accurate vibration analysis. Hollow slab should be modeled by refined mesh for accurate vibration analysis. For the efficiency of the Eigenvalue Analysis, an equivalent plate slab model when can relatively precisely represent the dynamic behavior of a one-way hollow slab system is used. In conclusion, equivalent plate models relatively precisely presented the dynamic characteristics of one-way hollows.

• Bulletin of the Korean Chemical Society
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• v.35 no.12
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• pp.3583-3589
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• 2014

This study evaluated a simple and useful route to the synthesis of mesoporous $TiO_2$ microcapsules with a hollow macro-core structure. A hydrophilic precursor sol containing the surfactants in the hydrophobic solvents was deposited on PMMA polymer surfaces modified by non-thermal plasma to produce mesoporous shells after calcination. The surface of the PMMA polymer spheres was coated with $NH_4F$ and CTAB to control the interfacial properties and promote the subsequent deposition of inorganic sols. These hollow type mesoporous $TiO_2$ microcapsules could be applied as an efficient substrate for the immobilization of DNA oligonucleotides.

• Journal of the Optical Society of Korea
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• v.20 no.1
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• pp.1-7
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• 2016

Using coherence theory, the partially coherent flat-topped vortex hollow beam is introduced. The analytical equation for propagation of a partially coherent flat-topped vortex hollow beam in turbulent atmosphere is derived, using the extended Huygens-Fresnel diffraction integral formula. The influence of coherence length, beam order N, topological charge M, and structure constant of the turbulent atmosphere on the average intensity of this beam propagating in turbulent atmosphere are analyzed using numerical examples.

• Journal of Forest and Environmental Science
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• v.18 no.1
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• pp.97-105
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• 2001

The main objective of this study was to investigate effects of pigment mixed with different ratio on the double coated paper. Mineral pigments such as clay and ground calcium carbonate(GCC) as well as hollow sphere plastic pigment were used to evaluate the physical, optical properties and printabilities of double coated paper. The physical properties such as gloss and smoothness, and the printability(ink gloss) of double coated paper were measured to evaluate the effects of the bottom layer on improving the properties of top layer. The data indicated that the usage of hollow sphere plastic pigment for the bottom layer coating improved the surface properties of double coated paper, and that ink gloss was significantly influenced by the structure of bottom layer even when hollow sphere plastic pigment was used for the bottom layer coating.

• Journal of the Korean Institute of Intelligent Systems
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• v.20 no.6
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• pp.843-847
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• 2010

Recently, one of the most interesting issue in the intelligent robot and the industrial robot area is the design and an implementation of servo driver module based on motion network for hollow type joint module of all-in-one structure. In this paper, we designed and implemented for hollow type driver, and also verified the performance of the developed module through the experiment.

• Elastomers and Composites
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• v.55 no.4
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• pp.277-280
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• 2020

In this study, mesoporous hollow silica spheres were synthesized using a polystyrene core and cetyltriammonium chloride (CTACl) as a pore template, and a low-cost water glass instead of expensive tetraethyl orthosilicate (TEOS) as a precursor. In addition, the material was synthesized by varying the concentration of polystyrene. Later, the polystyrene core and CTACl were removed by firing in a high-temperature heat-treatment process. The synthesized product was analyzed by various methods, such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffractometry (XRD), and N2-sorption analysis. It was confirmed that the hollow silica sphere had a hexagonal structure with a Brunauer-Emmett-Teller (BET) specific area of 1623 ㎡/g.

• Journal of the Korean Institute of Gas
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• v.19 no.1
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• pp.23-27
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• 2015

The stress and deformation behavior safeties of cylindrical hollow rollers have been analyzed by the finite element method, and investigated for over design capability based on the computed results. According to the stress analysis result which is related to the strength of a hollow roller, the maximum stress of 39.8MPa in which is operated near the bearing for supporting a hollow roller structure is overestimated design as 15.9% level compared with a yield strength, 250MPa of a steel material. And the maximum deformation of 0.032mm in which is operated at the middle span of a total length of cylindrical hollow rollers is very small and sufficiently safe compared with a total length and a thickness of a hollow roller. Thus, the FEM computed results for a stress and deformation indicate that a current FEM analysis model of cylindrical hollow rollers is over designed.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.39 no.3
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• pp.230-238
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• 2003

An effect on the enhancing production of hollow 'jumbo' structures and the condition of artificial reefs (dice and hollow jumbo structure) by side scan sonar were described. The experiment of the capture of fish in the jumbo structures and control site (non-artificial site) by trammel net and traps was done twice every year from 1998 to 2000. The relative catches by trammel net between in the jumbo structure and in the control site was significantly different in number and in weight at 5% level and also that by traps significantly different in weight. The t-test of the catch of finespotted flounder showed that the hollow jumbo structure was regarded as a breeding field because the average size of the flounder in the jumbo site was smaller than that in the control site. The search on the condition of the artificial reefs (dice and hollow jumbo structure) was performed by side scanning sonar which showed various phase of it such as accumulated, dispersed, scouring and partly buried. The result implied that in the area of sand bottom with strong tide like the western sea of Korea, the current criterion for constructing artificial reef should be modified because of the sand moving on the bottom.

• Korean Journal of Materials Research
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• v.19 no.10
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• pp.517-521
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• 2009

Si-C composite with hollow spherical structure was synthesized using ultrasonic treatment of organosilica powder formed by hydrolysis of phenyltrimethoxysilane. The prepared powder was pyrolyzed at various temperatures ranging from 900 to 1300 $^{\circ}C$ under nitrogen atmosphere to obtain optimum conditions for Li-ion battery anode materials with high capacity and cyclability. The XRD and elemental analysis results show that the pyrolyzed Si/C composite at 1100 $^{\circ}C$ has low oxygen and nitrogen levels, which is desirable for increasing the electrochemical capacity and reducing the irreversible capacity of the first discharge. The solid Si-C composite electrode shows a first charge capacity of $\sim$500 mAhg$^{-1}$ and a capacity fade within 30 cycles of 0.93% per cycle. On the other hand, the electrochemical performance of the hollow Si-C composite electrode exhibits a reversible charge capacity of $\sim$540 mAhg$^{-1}$ with an excellent capacity retention of capacity loss 0.43% per cycle up to 30 cycles. The improved electrochemical properties are attributed to facile diffusion of Li ions into the hollow shell with nanoscale thickness. In addition, the empty core space provides a buffer zone to relieve the mechanical stresses incurred during Li insertion.

• Korean Journal of Materials Research
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• v.23 no.12
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• pp.667-671
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• 2013

We present an easy method of preparing two-dimensional (2D) periodic hollow tin oxide ($SnO_2$) hemisphere array gas sensors using polystyrene (PS) spheres as a template. The structures were fabricated by the sputter deposition of thin tin (Sn) metal over an array of PS spheres on a planar substrate followed by calcination at an elevated temperature to oxidize Sn to $SnO_2$ while removing the PS template cores. The $SnO_2$ hemisphere array structures were examined by scanning electron microscopy and X-ray diffraction. The structures were calcined at various temperatures and their sensing properties were examined with varying operation temperatures and concentrations of nitric oxide (NO) gas. Their gas-sensing properties were investigated by measuring the electrical resistances in air and the target gases. The measurements were conducted at different NO concentrations and substrate temperatures. A minimum detection limit of 30 ppb, showing a sensitivity of S = 1.6, was observed for NO gas at an operation temperature of $150^{\circ}C$ for a sample having an Sn metal layer thickness corresponding to 30 sec sputtering time and calcined at $600^{\circ}C$ for 2 hr in air. We proved that high porosity in a hollow $SnO_2$ hemisphere structure allows easy diffusion of the target gas molecules. The results confirm that a 2D hollow $SnO_2$ hemisphere array structure of micronmeter sizes can be a good structural morphology for high sensitivity gas sensors.