• Applied Chemistry for Engineering
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• v.29 no.3
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• pp.356-361
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• 2018

It is common to analyze volatile organic compound (VOC) or semi-VOC (SVOC) in a sample composed of a complex matrix consisting of multiple components such as bloods through a separation process. Adsorption is a physical phenomenon in which certain components accumulate on the surface of other phases. In order to overcome difficulties in the pretreatment process, an adsorption is frequently used. Solid phase microextraction (SPME) equipment with porous carbon carboxen (CAR) is an example of adsorption application. In this study, the adsorption of 4-octylphenol to carboxen was examined. To do so, the extraction efficiency for such solvents as dichloromethane ($CH_2Cl_2$, DCM), ethylacetate ($CH_3COOC_2H_5$, EA) and diethylether ($C_2H_5OC_2H_5$, $Et_2O$) was studied and also the derivatization reaction for 4-octylphenol with reagents of bistrimethylsilyltrifluoroacetamide (BSTFA), methylchloroformate (MCF) and pentafluorobenzylbromide (PFBBr) was compared. The combination of DCM and BSTFA showed good performance thus they were adopted for this study. Thermodynamic adsorption experiments showed that the adsorption process was endothermic and Freundlich isotherm equation was more suitable than Langmuir isotherm. It was also found that the adsorption followed a pseudo-$2^{nd}$ order kinetic model.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.26 no.2
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• pp.77-83
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• 2020

A series of foamed plastic sheets containing biomass (as HMR container) were developed via different foaming process temperatures, and their density, porosity, WVTR, and pore morphology were evaluated. Thermal stability of samples during re-heating the food in oven, change in morphology, density, porosity, and WVTR were investigated using a simulated thermal shock process according to MIL-STD-883E assay. As such, the pore size of samples was generally increased with increasing temperature of the foaming process. It can be explained that as foaming temperature increased, the viscosity of molten resins and the repulsive force against pore expansion decreased. In addition, an increase in the thermal shock cycle reduced the pore size and WVTR, while density increased because high temperature treatment that softened the sheet matrix was followed by a low temperature incubation, which contracted the matrix, thereby changing the physical and morphological properties of samples. However, an insignificant change in density was observed and WVTR tended to be decreased, indicating that as-prepared foamed plastic sheets could be used as a high thermal stable container for HMR application. Therefore, it found that the properties of newly developed HMR containers containing biomass were dependent on the foaming process temperature. Moreover, to better understanding of these newly developed containers, further investigations dealing with foaming process temperature based on various food items and cooking conditions are needed.

• Journal of the Korean Ceramic Society
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• v.32 no.5
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• pp.626-634
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• 1995

The SiC-porcelain powder mixtures containing 51.9wt% SiC are produced as by-products from the surface abrasion process of porcelain cores. This raw powders were used as starting materials for the synthesis of SiC containing ceramics. The specimen, which was fired at 135$0^{\circ}C$ from raw powders, had SiC, $Al_{2}O_{3}$, , cristobalite, mullite as crystalline phases, and the fractured microstructure showed dispersed SiC crystalline particles almost wetted with glassy matrix and spherical pores. Although the oxidation of SiC containing powder compacts wetted with glassy matrix and spherical pores. Although the oxidation of SiC containing powder compacts started at the range of 600~80$0^{\circ}C$ form the analysis of weight gain, the presence of $SiO_{2}$ crystallien phase and cristobalite was confirmed at 100$0^{\circ}C$ by XRD analysis. Mullitization of specimens was accelerated by preheating before the final firing. The specimen sintered at 135$0^{\circ}C$ after 100$0^{\circ}C$ preheating consisted of SiC, cristobalite, mullite as crystalline phases, and revealed 2.24g/$cm^{3}$ bulk density, 11.73% water adsorption, porous microstructure with small amount of glassy phase. SiC contents of specimens, which was 51.9 wt% in the raw powders, reduced to 37~22 wt% after firing at 135$0^{\circ}C$ depending on the preheating condition.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.109.2-109.2
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• 2010

세라믹 필터는 여러 종류의 분진제거 시스템에서 연소 배가스 정제를 위한 가장 적절한 소재로 알려져 있다. 현재까지 다양한 형태의 세라믹 필터가 개발되고 있는데, 캔들 타입(candle type), 튜브 타입(tubular type), 평판 타입(parallel flow type) 등이 그 예이다. 통상적으로 세라믹 캔들 필터는 가압유동층복합발전(PFBC, Pressurize Fluidized-Bed Combustion), 석탄가스화복합발전(IGCC, Integrated coal Gasification Combined Cycle), 석탄가스화연료전지복합발전(IGFC, Integrated coal Gasification Fuel cell Combined cycle)에서 고온 배가스 정제용으로 사용되고 있다. 일반적으로 IGCC나 CTL 합성가스 정제시스템의 경우에는 높은 고압(약 25기압)과 미세분진이 함유되어 있는 분위기에서 운전된다. 그러므로 이때 사용되는 초청정용 세라믹 집진필터는 고온, 고압 및 부식 환경에서 50 MPa 이상을 갖는 높은 강도와 내식성을 갖도록 개발되어야 하기 때문에 SiC(Silicon Carbide)가 가장 적절한 캔들 필터 소재로 적용되고 있다. 이에 따라 집진용 SiC 세라믹 캔들 필터를 개발하기 위해서는 고온에서 내산화성이 우수하고, 부피팽창에 의한 균열이 발생하지 않는 무기결합재의 선정 및 이를 통한 소재의 특성 최적화가 가장 중요한 부분이라 할 수 있다. 본 연구에서는 IGCC나 CTL 공정에 적용하기 위한 SiC 캔들 필터 소재 개발을 위해 래밍성형 공정으로 1m급의 탄화규소 캔들 필터 시작품을 제작하여 SiC 출발입자 크기와 무기계 결합재인 스트론튬 카보네이트의 첨가량 변화에 따른 필터 소재의 특성 평가를 수행하였다.

• Journal of the Korean Ceramic Society
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• v.45 no.9
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• pp.561-566
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• 2008

Carbon fiber fabric-silicon carbide composites were fabricated by liquid silicon infiltration (LSI) process. The porous two-dimensional carbon fiber fabric performs were prepared by 13 plies of 2D-plain-weave fabric in a three laminating method, [0/90], [${\pm}45$], [$0/90/{\pm}45$] lay-up, respectively. Before laminating, a thin pyrolytic carbon (PyC) layer deposited on the surface of 2D-plain weave fabric sheets as interfacial layer with $C_3H_8$ and $N_2$ gas at $900^{\circ}C$. A densification of the preforms for $C_f-Si-SiC$ matrix composite was achieved according to the LSI process at $1650^{\circ}C$ for 30 min. in vacuum atmosphere. The bending strength of the each composite were measured and the microstructural consideration was performed by a FE-SEM.

• Journal of Welding and Joining
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• v.15 no.4
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• pp.126-135
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• 1997

$H_2/O_2$ 비에 따른 Hybrid HVOF 용사된 $Cr_3C_2$-7wt%(NiCr) 용사층의 특성 및 산화거동 This study was performed to investigate the influence of fuel/oxygen ratio (F/O=3.2, 3.0, 2.8) on the characteristics and the oxidation behavior of the hybrid-HVOF sprayed $Cr_3C_2$-7wt%NiCr coatings. Decomposition and the oxidation of the $Cr_3C_2$was occured during spraying. The degree of transformation from $Cr_3C_2$to $Cr_7C_3$ was increased with decreasing the F/O ratio. The microstructural differences of the as sprayed coating with F/O ratio can not be distinguished, However, large pores were diminished and then the coatings became dense by heat treatment. Microhardness of the as-sprayed specimen which sprayed with F/O=3.0 condition was hightest ($Hv_{300}$=1140) and the hardness was increased to 1500 after heat treatment at $600^{\circ}C$ for 50hrs in air. It was supposed that hardness was increased due to the formation of $Cr_2O_3$ within $Cr_3C_2$/$Cr_7C_3$matrix and the densification of coating layer during heat treatment. Apparent activation energy for oxidation was varied from 21.2 kcal$mol^{-1}K^{-1}$ to 23.8 kcal$mol^{-1}K^{-1}$ with respect to the F/O ratio. The surface morphology was changed to porous and oxide chusters were grown after oxidation $1000^{\circ}C$ for 50 hours by the aggressive evolution of gas phase ($CrO_3$ and$CO_2$). The oxide cluster was composed of Ni and Cr.

• Journal of the Korean Vacuum Society
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• v.16 no.3
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• pp.221-226
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• 2007

DBR (distributed Bragg reflectors) PSi (porous silicon) composite films displaying dual optical properties, both optical reflectivity and photoluminescence had been developed. DBR PSi samples were prepared by electrochemical etch of heavily doped $p^{++}-type$ silicon wafers (boron doped, polished on the <100> face, resistivity of $0.8-1.2m{\Omega}-cm$, Siltronix, Inc.). Free-standing DBR PSi films were treated with PMMA (polymethyl methacrylate) to produce flexible, stable composite materials in which the PSi matrix is covered with PMMA containing photoluminescent polysiloles. Optical characteristics of DBR PSi/polysilole-impregnated PMMA composite materials exhibit both their photonic reflectivity at 565 nm and photoluminescence at 510 nm, simultaneously. A possible application of this materials will be discussed.

• Korean Journal of Materials Research
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• v.26 no.5
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• pp.250-257
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• 2016

Octahedral $Co_3O_4$/carbon nanofiber (CNF) composites are fabricated using electrospinning and hydrothermal methods. Their morphological characteristics, chemical bonding states, and electrochemical properties are used to demonstrate the improved photovoltaic properties of the samples. Octahedral $Co_3O_4$ grown on CNFs is based on metallic Co nanoparticles acting as seeds in the CNFs, which seeds are directly related to the high performance of DSSCs. The octahedral $Co_3O_4$/CNFs composites exhibit high photocurrent density ($12.73mA/m^2$), superb fill factor (62.1 %), and excellent power conversion efficiency (5.61 %) compared to those characteristics of commercial $Co_3O_4$, conventional CNFs, and metallic Co-seed/CNFs. These results can be described as stemmnig from the synergistic effect of the porous and graphitized matrix formed by catalytic graphitization using the metal cobalt catalyst on CNFs, which leads to an increase in the catalytic activity for the reduction of triiodide ions. Therefore, octahedral $Co_3O_4$/CNFs composites can be used as a counter electrode for Pt-free dye-sensitized solar cells.

• Composites Research
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• v.18 no.1
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• pp.55-66
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• 2005

Beside fire resistance, for Phenolic Composites(here-in-after PCs), in actual, moisture resistance are also needed when they are applied to components in wet uses such as in Naval vessels and in off-shore operations where direct water contact may be expected. PCs have so-called 'Micro-porous' when they are made by normal GRP manufacturing techniques, which causes much larger amounts of water absorption in them to higher level of around $7\%$. So, this figure, which indicate impending disaster in a polyester matrix laminate, has made some specifiers suspicious of the effect of the water on mechanical performance of PC in 'wet' service. To solve this problem, a large amount work has been carried out by workers in UK and US. This paper is an attempt to explain that the effect of the high water absorption of PCs is not the disaster that some 'prophets' may foretell. Let's open our next door fur better society much safetyfied by our own efforts with PCs. like in UK.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.8
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• pp.450-457
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• 2015

In this research a adsorbent, PVA-Zeolite bead, was prepared by immobilizing zeolite with PVA. The results of XRD and SEM analysis showed that the prepared PVA-Zeolite beads had porous structure and the zeolite particles were in mobilized within the internal matrix of the beads. The adsorption properties of Sr ion and Cs ion with the adsorbent were studied by different parameters such as effect of pH, adsorption rate, and adsorption isotherm. The adsorption of Sr ion and Cs ion reached equilibrium after 540 minutes. The adsorption kinetics of both ions by the PVA-Zeolite beads were fitted well by the pseudo-second-order model more than pseudo-first-order model. The equilibrium data fitted well with Langmuir isotherm model. The maximum adsorption capacities of Sr ion and Cs ion calculated from Langmuir isotherm model were 52.08 mg/g and 58.14 mg/g, respectively. The external mass transfer step was very fast compared to the intra-particle diffusion step in the adsorption process of Cs ion and Sr ion by the PVA-Zeolite beads. This result implied that the rate controlling step was the intra-particle diffusion step.