• Bulletin of the Korean Chemical Society
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• v.32 no.3
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• pp.921-926
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• 2011

This study investigates a root cause of the improved rate performance of $LiFePO_4$ after metal doping to Fesites. This is because the metal doped $LiFePO_4$/C maintains its initial capacity at higher C-rates than undoped one. Using $LiFePO_4$/C and doped $LiFe_{0.97}M_{0.03}PO_4$/C (M=$Al^{3+}$, $Cr^{3+}$, $Zr^{4+}$), which are synthesized by a mechanochemical process followed by one-step heat treatment, the Li content before and after chemical delithiation in the $LiFePO_4$/C and the binding energy are compared using atomic absorption spectroscopy (AAS) and X-ray photoelectron spectroscopy (XPS). The results from AAS and XPS indicate that the low Li content of the metal doped $LiFePO_4$/C after chemical delithiation is attributed to the low binding energy induced by weak Li-O interactions. The improved capacity retention of the doped $LiFePO_4$/C at high discharge rates is, therefore, achieved by relatively low binding energy between Li and O ions, which leads to fast Li diffusivity.

• Composites Research
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• v.26 no.3
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• pp.189-194
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• 2013

This paper deals with the study of mechanical properties and impact energy absorbed by composites, made by using thermoplastic and thermoset as matrix, flax fiber and nanoclay as reinforcements. The nanoclay was sprayed on the fiber laminate directly after mixing with ethanol. This experiment designed by Taguchi method and have variable factors, i.e three types of fiber direction(F), three different nanoclay wt%(N) and three spray gun hole shapes(S). According to these conditions, composites were made and the optimum conditions were found to be F1N3S1, F1N2S1, F1N2S1 and F3N2S1 for thermoplastic, and F1N3S2, F1N3S2, F1N2S2 and F3N2S1 for thermoset which were matched with tensile strength, modulus, total impact absorbed energy and heat release rate respectively.

• Culinary science and hospitality research
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• v.4
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• pp.249-269
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• 1998

What satisfies the desire of human beings about taste most easily is sweet taste, and it has seemed that the pronoun of sweet taste is sugar. Sugar is used in confectionery and bread-making essentially, and it has influence on the structure and touch of baked confectionery. In addition, if we soften the and apply heat, coloring is made. Thus, it colors good. It doesn't have a sweet taste, but it has the effect to emit fragrance variously, balance and soften the product. The kinds of sugar are very diverse, and it is sugar to be referred to as white sugar is used most frequently. In this study, this researcher examined the classification of physicochemical property and melting point etc. of sugar in confectionery and bread-making through theoretical study, about the simple classification of sugar. In addition, this researcher approached about the role of sugar in confectionery and bread-making and about the influence to have when it is more or less than proper quantity, centering around function. As the result, this researcher extracted the importance of sugar in confectionery and bread-making. It means that the increase of 5% of sugar quantity decreases the absorption quantity of moisture by 1% in bread-making and that the excess of 8% of sugar slow the action of yeast in straight method. Besides, there are the properties such as absorptive property, permeability, storage nature, aging prevention of starch, oxidation restraint of oils and fats, the gelation action of pectin, the fermentation acceleration of yeast, and the emulsification-maintaining-nautre and antiseptics effect of fat-soluble material. And in confectionery, sugar makes fragrance and peel color, increases the storage nature with moisture maintenance and has the softening effect. So, it is considered that the attitude to study and make efforts continuously on the basis of the role of sugar will have to be unfolded in confectionery and bread-making.

• Journal of the Korean Ceramic Society
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• v.31 no.1
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• pp.79-87
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• 1994

Aluminum nitride was hydrolyzed in contact with water, evolving the reaction heat of 172 cal/g within 12 hours to form alumina trihydrates. At 4$0^{\circ}C$ >, amorphous alumina hydrate was easily produced by the spontaneous breaks of AlN particle at the beginning of the hydrolysis process, while bayerite was formed by the dissolution-recrystallization processes of amorphous alumina hydrate at the temperature between 4$0^{\circ}C$ and 6$0^{\circ}C$, and pseudo-boehmite was generated on the surface of AlN particle by the condensation process of the corresponding phase at 6$0^{\circ}C$ <. The longer the hydrolysis timje or the higher the value of pH in solution, the more the bayerite phase was produced. However, pseudo-boehmite was easily generated under the following favorable conditions; when the hydrolysis reaction occured rapidly at the beginning and when the absorption of OH radical on the surface of AlN particle was disturbed by ethyl alcohol in a solution. However, aluminum nitride was hardly hydrolyzed in a solution of pH 2.0.

• Journal of Hydrogen and New Energy
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• v.27 no.6
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• pp.642-650
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• 2016

One of the most feasible solution for reducing the excessive energy consumption and carbon dioxide emission is usage of more efficient fuel such as hydrogen. As is well known, there are three viable technologies for storing hydrogen fuel: compressed gas, metal hydride absorption, and cryogenic liquid. In these technologies, the storage for liquid hydrogen has better energy density by weight than other storage methods. However, the cryogenic liquid storage has a significant disadvantage of boiling losses. That is, high performance of thermal insulation systems must be studied for reducing the boiling losses. This paper presents an experimental study on the effective thermal conductivities of the composite layered insulation with aerogel blankets($Cryogel^{(R)}$ Z and $Pyrogel^{(R)}$ XT-E) and Multi-layer insulation(MLI). The aerogel blankets are known as high porous materials and the good insulators within a soft vacuum range($10^{-3}{\sim}1$ Torr). Also, MLI is known as the best insulator within a high vacuum range(<$10^{-6}{\sim}10^{-3}$ Torr). A vertical axial cryogenic experimental apparatus was designed to investigate the thermal performance of the composite layered insulators under cryogenic conditions as well as consist of a cold mass tank, a heat absorber, annular vacuum space, and an insulators space. The composite insulators were laminated in the insulator space that height was 50 mm. In this study, the effective thermal conductivities of the materials were evaluated by measuring boil-off rate of liquid nitrogen and liquid argon in the cold mass tank.

• Resources Recycling
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• v.18 no.3
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• pp.27-35
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• 2009

To solve resource exhaustion and waste management problems caused by mass consumption, there are many efforts to change from resource consumption system to recycling system. Specially, interests about management of construction waste have increased, but efficient recycling system of waste concrete is not established yet. In this study, high quality recycled aggregate processing circuit was developed to recycle waste concrete. From the waste concrete which is a hydrated compound with coarse aggregate, fine aggregate, and cement material, high quality recycled coarse aggregate for concrete making was produced by autogenous milling and heat pretreatment method. After then, refinement process was performed to separate fine aggregate and cement material from waste concrete fines by sink float separation and hindered-settling separation. As a result, high quality recycled aggregate was produced from waste concrete by developed processing circuit.

• Journal of the Korean GEO-environmental Society
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• v.2 no.1
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• pp.91-101
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• 2001

This paper investigates the effectiveness of quick lime piles for soft ground improvement. The field tests based on the results of the laboratory test were performed, and the results of field tests were compared with those of numerical analyses(FEM). The results of the field test showed that the domestic quick lime was very effective in reducing the water contents of the surrounding ground quickly due to its characteristics such as digestion, absorption, and exothermic reactions. Accordingly, consolidation occurred without any additional load increment and the shear strength of surrounding ground was increased more than twice. Therefore the quick lime pile method could be considered as an excellent improvement technique reducing the improvement period for soft ground. For the practical applications of the quick lime pile method, issues such as hydration heat, particulation and equipment enhancement should be solved through continuous research and development.

• Journal of the Korean Ceramic Society
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• v.49 no.6
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• pp.620-624
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• 2012

The role of moisture remaining inside the deposition chamber during the formation of the cubic boron nitride (c-BN) phase in BN film was investigated. BN films were deposited by an unbalanced magnetron sputtering (UBM) method. Single-crystal (001) Si wafers were used as substrates. A hexagonal boron nitride (h-BN) target was used as a sputter target which was connected to a 13.56 MHz radiofrequency electric power source at 400 W. The substrate was biased at -60 V using a 200 kHz high-frequency power supply. The deposition pressure was 0.27 Pa with a flow of Ar 18 sccm - $N_2$ 2 sccm mixed gas. The inside of the deposition chamber was maintained at a moisture level of 65% during the initial stage. The effects of the evacuation time, duration time of heating the substrate holder at $250^{\circ}C$ as well as the plasma treatment on the inside chamber wall on the formation of c-BN were studied. The effects of heating as well as the plasma treatment very effectively eliminated the moisture adsorbed on the chamber wall. A pre-deposition condition for the stable and repeatable deposition of c-BN is suggested.

• Journal of Sensor Science and Technology
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• v.17 no.6
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• pp.437-446
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• 2008

Single crystalline ${ZnIn_2}{Se_4}$ layers were grown on thoroughly etched semi-insulating GaAs (100) substrate at $400^{\circ}C$ with hot wall epitaxy (HWE) system by evaporating ${ZnIn_2}{Se_4}$ source at $630^{\circ}C$. The crystalline structure of the single crystalline thick films was investigated by the photoluminescence (PL) and Double crystalline X-ray rocking curve (DCRC). The carrier density and mobility of ${ZnIn_2}{Se_4}$ single crystalline thick films measured from Hall effect by van der Pauw method are $9.41{\times}10^{16}cm^{-3}$ and $292cm^2/V{\cdot}s$ at 293 K, respectively. The temperature dependence of the energy band gap of the ${ZnIn_2}{Se_4}$ obtained from the absorption spectra was well described by the Varshni's relation, $E_g(T)$=1.8622 eV-$(5.23{\times}10^{-4}eV/K)T^2$/(T+775.5 K). After the as-grown ${ZnIn_2}{Se_4}$ single crystalline thick films was annealed in Zn-, Se-, and In-atmospheres, the origin of point defects of ${ZnIn_2}{Se_4}$ single crystalline thick films has been investigated by the photoluminescence (PL) at 10 K. The native defects of $V_{Zn}$, $V_{Se}$, $Zn_{int}$, and $Se_{int}$ obtained by PL measurements were classified as a donors or acceptors type. And we concluded that the heat-treatment in the Se-atmosphere converted ${ZnIn_2}{Se_4}$ single crystalline thick films to an optical p-type. Also, we confirmed that In in ${ZnIn_2}{Se_4}$/GaAs did not form the native defects because In in ${ZnIn_2}{Se_4}$ single crystalline thick films existed in the form of stable bonds.

• Genomics & Informatics
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• v.4 no.2
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• pp.71-76
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• 2006

We have investigated biological responses to radiofrequency (RF) radiation in in vitro and in vivo models. By measuring the levels of heat shock proteins as well as the activation of mitogen activated protein kinases (MAPKs), we could not detect any differences upon RF exposure. In this study, we used more sensitive method to find the molecular responses to RF radiation. Jurkat, human T-Iymphocyte cells were exposed to 1763 MHz RF radiation at an average specific absorption rate (SAR) of 10 W/kg for one hour and harvested immediately (R0) or after five hours (R5). From the profiles of 30,000 genes, we selected 68 differentially expressed genes among sham (S), R0 and R5 groups using a random-variance F-test. Especially 45 annotated genes were related to metabolism, apoptosis or transcription regulation. Based on support vector machine (SVM) algorithm, we designed prediction model using 68 genes to discriminate three groups. Our prediction model could predict the target class of 19 among 20 examples exactly (95% accuracy). From these data, we could select the 68 biomarkers to predict the RF radiation exposure with high accuracy, which might need to be validated in in vivo models.