• Proceedings of the Korean Institute of Building Construction Conference
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• 2017.11a
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• pp.94-95
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• 2017

Oyster shell is produce by shucking process in oyster farming in southern coast of Korea. In average, about 6.7kg of oyster shell is produced as an industrial waste for 1kg of oyster flesh, and even only in last year, it is estimated that about 150,000ton of oyster shell is produced. Oyster shell is light weighted and the strength characteristic of it is similar to send. We produced mortar test piece using grounded oyster shell powder according to Filler and Fiber. So I wanted to measure the strength and use it as a baseline for follow-up studies.

• Journal of Environmental Science International
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• v.15 no.11
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• pp.1027-1034
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• 2006

Antimicrobial powder was made by exchanging silver ion on calcined oyster shell. On the purpose of application to water clarifier, bail-type media mixed with antimicrobial powder and $0{\sim}30%$ white kaoline were made. The sterilization effect, pore size distribution and zeta potential was tested to indicate the condition for the media of water clarifier. From these tests, it was confirmed that this media have an excellent sterilization power on $G^-\;and\;G^+$ germs. As the concentration of the exchanged silver ion increased, the surface charge density of the anions on the surface of the media also increased. The surface pore size decreased with the concentration of silver ion and 20% more white kaoline ratio. Consequently, mixing ratio of white kaoline would appear to indicate the optimun condition as media have sterilization power.

• Journal of the East Asian Society of Dietary Life
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• v.22 no.6
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• pp.795-801
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• 2012

This study was conducted to investigate the effects of loquat (Eriobotrya japonica Lindl.) leaf powder (LLP) on quality characteristics of dumpling shells. Dumpling shell samples were prepared with wheat flour containing different amounts of LLP, and their characteristics were then investigated. Amylography revealed that the gelatinization temperature of the LLP-wheat flours composite increased, while the initial viscosity at $95^{\circ}C$, viscosity at $95^{\circ}C$ after 15 minutes, and maximum viscosity, all decreased with increasing LLP content. As increasing amounts of LLP were added, the L and a values were reduced, whereas the b value was increased. Moreover, the addition of LLP increased hardness, cohesiveness, and adhesiveness, while it reduced springiness. Overall, sensory evaluation revealed that dumpling shells with 5% LLP were preferred more than other samples.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2007.11a
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• pp.41-44
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• 2007

Recently, the strenuous industrial waste is scattered and one of the oyster also make the serious environmental contamination. The purpose of this study is investigating an utilization ability as calcium binder of the oyster with Hwang-To according to a rate(10%, 20%, 30%, 40%, 50%). This study grasp physical properties of the oyster powder, bake production of the paste, and conduct the flow test, stiff time test and strength test. According to baking condition, strength of $1000^{\circ}C$(120minutes, rate 30%) is higher than any other condition. The oyster powder from above $900^{\circ}C$ seem possibility as binder hereafter. It is thought that the continuous research will be necessary.

• Journal of Powder Materials
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• v.21 no.5
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• pp.360-365
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• 2014

$SnO_2-CoO$/carbon-coated CoO core/shell nanowire composites were synthesized by using electrospinning and hydrothermal methods. In order to obtain $SnO_2-CoO$/carbon-coated CoO core/shell nanowire composites, $SnO_2-Co_3O_4$ nanowire composites and $SnO_2-Co_3O_4$/polygonal $Co_3O_4$ core/shell nanowire composites are also synthesized. To demonstrate their structural, chemical bonding, and morphological properties, field-emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy were carried out. These results indicated that the morphologies and structures of the samples were changed from $SnO_2-Co_3O_4$ nanowires having cylindrical structures to $SnO_2-Co_3O_4/Co_3O_4$ core/shell nanowires having polygonal structures after a hydrothermal process. At last, $SnO_2-CoO$/carbon-coated CoO core/shell nanowire composites having irregular and high surface area are formed after carbon coating using a polypyrrole (PPy). Also, there occur phases transformation of cobalt phases from $Co_3O_4$ to CoO during carbon coating using a PPy under a argon atmosphere.

• Journal of Powder Materials
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• v.25 no.2
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• pp.132-136
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• 2018

Core/shell CdSe/ZnS quantum dots (QDs) are synthesized by a microfluidic reactor-assisted continuous reactor system. Photoluminescence and absorbance of synthesized CdSe/ZnS core/shell QDs are investigated by fluorescence spectrophotometry and online UV-Vis spectrometry. Three reaction conditions, namely; the shell coating reaction temperature, the shell coating reaction time, and the ZnS/CdSe precursor volume ratio, are combined in the synthesis process. The quantum yield of the synthesized CdSe QDs is determined for each condition. CdSe/ZnS QDs with a higher quantum yield are obtained compared to the discontinuous microfluidic reactor synthesis system. The maximum quantum efficiency is 98.3% when the reaction temperature, reaction time, and ZnS/CdSe ratio are $270^{\circ}C$, 10 s, and 0.05, respectively. Obtained results indicate that a continuous synthesis of the Core/shell CdSe/ZnS QDs with a high quantum efficiency could be achieved by isolating the reaction from the external environment.

• Resources Recycling
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• v.17 no.4
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• pp.21-29
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• 2008

Waste shell powder was added to the high density polyethylene(HDPE), and resultant mechanical properties and flame retardancy were analyzed in terms of shell content. Compatibilizer(PE-g-MA) was used to enhance the mechanical properties of the prepared HDPE/shell composites, and several flame retardant agents($Al_2O_3$, $Sb_2O_3$) were utilized to improve flame retardancy. Addition of the compatibilizer resulted in an improved mechanical properties due to the increased interfacial bonding between HDPE matrix and shell powder. In the case of impact strength, it even reached to the impact strength of pure HDPE. Also the addition of the flame retardant agents did not exhibit mechanical property decrease. UL-94 flammability test on the prepared HDPE/shell composites indicated that at 40wt% of shell only inclusion, time to ignite the flame and the total time of flame duration increased. When flame retardant agents mixed with shell powder were added to the HDPE matrix, improved flame retardancy was observed. Generally, flame retardancy effect of $Al_2O_3$ was better than $Sb_2O_3$. UL-94 V-0 classification was observed for the specimens with $Al_2O_3$ and compatibilizer at more than 40wt% shell, and also for specimens with $Sb_2O_3$ and compatibilizer at all shell content.

• Journal of Powder Materials
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• v.26 no.6
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• pp.463-470
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• 2019

Fe₃O₄/SiO₂/YVO₄:Eu³⁺ multifunctional nanoparticles are successfully synthesized by facile stepwise sol-gel processes. The multifunctional nanoparticles show a spherical shape with narrow size distribution (approximately 40 nm) and the phosphor shells are well crystallized. The Eu³⁺ shows strong photoluminescence (red emission at 619 nm, absorbance at 290 nm) due to an effective energy transfer from the vanadate group to Eu. Core-shell structured multifunctional nanoparticles have superparamagnetic properties at 300 K. Furthermore, the core-shell nanoparticles have a quick response time for the external magnetic field. These results suggest that the photoluminescence and magnetic properties could be easily tuned by either varying the number of coating processes or changing the phosphor elements. The nanoparticles may have potential applications for appropriate fields such as laser systems, optical amplifiers, security systems, and drug delivery materials.

• Journal of Powder Materials
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• v.23 no.6
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• pp.409-413
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• 2016

Electrical wire explosion in liquid media is a promising method for producing metallic nanopowders. It is possible to obtain high-purity metallic nanoparticles and uniform-sized nanopowder with excellent dispersion stability using this electrical wire explosion method. In this study, Ni-Fe alloy nanopowders with core-shell structures are fabricated via the electrical explosion of Ni-Fe alloy wires 0.1 mm in diameter and 20 mm in length in de-ionized water. The size and shape of the powders are investigated by field-emission scanning electron microscopy, transmission electron microscopy, and laser particle size analysis. Phase analysis and grain size determination are conducted by X-ray diffraction. The result indicate that a core-shell structured Ni-Fe nanopowder is synthesized with an average particle size of approximately 28 nm, and nanosized Ni core particles are encapsulated by an Fe nanolayer.

• Korean Chemical Engineering Research
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• v.46 no.1
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• pp.99-105
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• 2008

Core-shell structured $BaTiO_3$ powders were produced via nano-coating of $Cr_2O_3$ and $Mn_2O_3$ to barium titanate powder system for MLCCs. From preliminary experiments, the optimal solution reaction condition employing using $KMnO_4$, $K_2Cr_2O_4$ and sulfur was established. Not only powders of $Cr_2O_3$ and $Mn_2O_3$ were synthesized but also their coating on $BaTiO_3$ powders were peformed under the same reaction condition. The coating was carried out in two ways, one-step and two-step, and its results were characterized for comparison. Conclusively speaking, two oxide additives were coated onto the $BaTiO_3$ powder surface with high quality and excellent reaction yield even under mild condition, which indicates that the contents as well as the properties of additive shell layer can be precisely controlled with rather ease.