• Journal of Sensor Science and Technology
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• v.7 no.3
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• pp.218-224
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• 1998

2nO and $Al_{2}O_{3}$ powder were weighed in 1 : 1 mole ratio and ball-milled in ethanol for 3 h. Dried mixture were pressed and then sintered at $900^{\circ}C{\sim}1200^{\circ}C$ for 3 h in vacuum($3{\times}10^{-5}$ Torr). According to XRD, remnant ZnO and $Al_{2}O_{3}$ not converted to $ZnAl_{2}O_{4}$ were observed up to $1100^{\circ}C$, which were completely changed to$ZnAl_{2}O_{4}$ ternary compound at $1200^{\circ}C$. Optical bandgap is calculated at 4.75 eV. With increasing sintering temperature, PL spectrums shifted to shorter wavelengths and are appeared 430nm at $1200^{\circ}C$.

• Korean journal of food and cookery science
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• v.2 no.1
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• pp.59-64
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• 1986

This study was designed to revive the disappeared Younsa and to investigate the optimum processing condition and characteristics of Younsa nade of the glutinous rice powder. Agitating time of base mixture, thickness of Younsa base, and frying time were examined as the influencing factors in Younsa processings. The textural parameters of Younsa were determined by sensory cvaluation and hardness of Younsa was measured by Rheometer. The results were found as follows; 1. In the sensory evaluation, 1) The Younsa base agitated for 10 minutes by agitating machine was favorable. It, however, did not showed any significant difference among products prepared under varying agitaing time-10 minutes, 20 minutes, and 30 minutes. (p<0.05) 2) The thinnest Younsa base (5 cm$\times$4cm, 1.1-1.5g) showed the most favorable quality and the second quality went to 5cm$\times$4cm, 1.6-2.0g, the third 5cm$\times$4cm, 2.1-2.5g, the fourth 5 cm$\times$4 cm, 2.6-3.0g. (p<0.05) 3) In examination of varying frying time, the optimal time for frying Younsa was 12 minutes was 12 minutes in $150 ^{\circ}C$. However, the quality was found no significant difference between 12 minutes's fried Younsa and 14 minutes's. (p<0.05). 2. The hardness of the most favorable Younsa, agitated for 10 minutes, the thinnest (5 cm$\times$4 cm, 1.1-1.5g), ana fried for 12 minutes in $150^{\circ}C$ was 0.59-0.73 kg/wt measured by Rheometer. The thickest Younsa base (5 cm$\times$4 cm, 2.6-3.0g) is the hardest (1.26 kg/wt). The most optimal conditions in this experiment were found the same ones which was written in historical literature.

• Korean Journal of Food Science and Technology
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• v.27 no.5
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• pp.673-679
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• 1995

Pectinesterase(PE) has been definitively established as the causative agent for clarification of citrus juice and gelation of frozen concentrates. This enzyme is present in multiple forms in citrus fruit. Although representing a minor fraction of the total PE activity, thermostable pectinesterase(TSPE) accounts for the severe time/temperature processing treatment required to inactivate PE. This study was undertaken to separate and purify thermolabile pectinesterase(TLPE) and TSPE from the crude PE extracts of Valencia orange rag-pulp powder. The approach taken was to carry out the three kind of chromatographies of CM-Sephadex C-50, Phenyl Sepharose CL-4B and CM-Biogel A to the unheated crude PE or the heated crude PE. All of them used could increase the purity of PEs and, specially, Phenyl Sepharose CL-4B chromatography could separate crude PE as the mixture of PEs into two forms of TLPE and TSPE. The purified TLPE had specific activity of 1,005 units/mg, yield of 13.6% and purification of 35 fold, while the TSPE separated from the unheated crude PE showed specific activity of 3,115 units/mg, yield of 1.5% and purification of 100.5 fold, and another TSPE from the heated crude PE was found to be specific activity of 1,803 units/mg, yield of 15.4% and purification of 140 fold.

• Korean Journal of Food Science and Technology
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• v.21 no.1
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• pp.127-135
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• 1989

The volatile components of nutmeg, cumin, cardamon, turmeric, coriander, clove, allspice, cassia, fennel, celery seed and black pepper, having a characteristic spicy aroma and being used as an ingradient of curry powder, were investigated. After steam distillation followed by extraction with diethyl ether: n-pentane(2:1, v/v) mixture, the volatile components were identified by capillary GC and GC/MS. As a result, following major compounds were identified. ${\alpha}-pinene(11.06%)$, ${\beta}-pinene(11.17%)$ and myristicin(19.98%) in nutmeg, cuminaldehyde(37.68%) in cumin, ${\alpha}-terpineol(47.33%)$ and 1, 8-cineol(20.56%) in cardamon, linalool(61.72%) in coriander, eugenol(63.63%) and eugenol acetate(20.59%) in clove, eugenol(80.12%) and methyl eugenol(10.85%) in allspice, cinnamaldehyde(82.29%) in cassia, anethole(79.92%) in fennel.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2007.04a
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• pp.25-28
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• 2007

In this study we measured the changes according to time respectively on the basis of 0, 30, 60 and 90 minutes, taking into consideration the decline in fluidity of concrete according to elapsed time to analyze manufacturing capability of batcher plant according to elapsed time of ready-mixed concrete manufactured in batcher plant, and offer basic data for mixture design of ultra-high strength concrete. The proportion of water-binder was 23.55, water content was 160kg/m3, proportion of replacement of crushed sand was 0, 20 and 40% at 3 level, and we applied to the same condition of triaxial component using blast furnace slag powder and silica fume as admixture. And to meet the demand of certain fluidity, we measured respectively on property before and after hardening of ultra-high strength concrete using superplasticizer. As a result of experiment, before hardening of ultra-high strength concrete showed the best fluidity in conditions of crushed sand replacement rates of 20% and superplasticizer composition of 1.95%, but it appeared that fluidity drops as time goes by in the same composition condition. And it appeared that when it comes to hardened, the changes of compression strength according to elapsed time by crushed sand replacement rates were within 1MPa. Therefore, it turned out that the difference of strength according to elapsed time was low and compression strength of 280dys in composition mentioned above appeared highly as 88MPa.

• Carbon letters
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• v.16 no.2
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• pp.78-85
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• 2015

Activated carbons (ACs) were prepared by activation of coal tar pitch (CTP) in the range of $700^{\circ}C-1000^{\circ}C$ for 1-4 h using potassium hydroxide (KOH) powder as the activation agent. The optimal activation conditions were determined to be a CTP/KOH ratio of 1:4, activation temperature of $900^{\circ}C$, and activation time of 3 h. The obtained ACs showed increased pore size distribution in the range of 1 to 2 nm and the highest specific capacitance of 122 F/g in a two-electrode system with an organic electrolyte, as measured by a charge-discharge method in the voltage range of 0-2.7 V. In order to improve the performance of the electric double-layer capacitor electrode, various mixtures of CTP and petroleum pitch (PP) were activated at the optimal activation conditions previously determined for CTP. Although the specific capacitance of AC electrodes prepared from CTP only and the mixtures of CTP and PP was not significantly different at a current density of 1 A/g, the AC electrodes from CTP and PP mixtures showed outstanding specific capacitance at higher current rates. In particular, CTP-PP61 (6:1 mixture) had the highest specific capacitance of 132 F/g, and the specific capacitance remained above 90% at a high current density of 3 A/g. It was found that the high specific capacitance could be attributed to the increased micro-pore volume of ACs with pore sizes from 1 to 2 nm, and the high power density could be attributed to the increased meso-pore volume.

• Journal of the Korean Ceramic Society
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• v.39 no.7
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• pp.663-668
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• 2002

Cation exchange capacity of clay, white clay and zeolite was estimated by performing the powder adsorption test for 6 different heavy metal (Cd, Cr, Cu, Fe, Pb and Zn) standard solutions whose concentrations were varied by 5,10,15 and 20 ppm. The adsorption rate of heavy metals decreased with increasing the concentration of standard heavy metal solutions. The adsorption rate of the clay and the white clay showed more than 80% for the all tested heavy metals except Cr and especially above 99% for the Fe and the Pb. The Cr adsorption rate of the mixture of the clay and the white clay increased, however, that of Zn decreased. The adsorption rate of Cr and Zn showed relatively lower values as compared with those of the other heavy metals because the cation exchange H$\^$+/ ions and heavy metal ions of the clay or the white clay were in competition at low pH region.

• Resources Recycling
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• v.10 no.6
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• pp.29-34
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• 2001

Fly ash powders were refined and separated into fine and coarse size by multi-air classification, and each particle was used for synthesizing mullite and zeolite. Mullite was prepared by sintering the mixture of fine fly ash with mean size of 6.5 $\mu$m and $A1_2$$O_3$powder at above $1450^{\circ}C$. Zeolite was synthesized through hydrothermal reaction with coarse fly ash mean size of $56.3\mu$m in 3.5 M NaOH solution at $120^{\circ}C$. The whole range of particle size can be recycled through size classification into fine and coarse fractions, which are used for syntheses of inorganic materials.

• Food Science and Preservation
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• v.11 no.2
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• pp.154-159
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• 2004

In order to develop of health-oriented convenience foods for rice consumption, functional Misutkaru drink was made by adding several medicinal herbs extracts to fundamental Misutkaru based cereal powder(rice, barley and soybean). Fundamental Misutkaru drink was prepared with the ratio of cereal mixed rice(5g), barley(5g) and soybean(5g) on water (100 mL) and several medicinal herbs extracts. Liriopis Tuber(50%), Omija(15%), Ginseng(10%) and Jujube(25%) were mixed to fundamental Misutkaru as functional Misutkaru. And then it was extracted to added water of 10times during 36hrs at 75$^{\circ}C$. For instant Misutkaru drink of health-oriented convenience foods, mixture of them was made with fundamental Misutkaru drink(80%), extract of several medicinal herbs(20%), and it's sensory score was high. Autoclaved functional Misutkaru drink for long storage period was changed rheological type badly. Overall acceptability and storage period of nonautoclaved functional Misutkaru drink to added extract of several medicinal herbs was higher than fundamental Misutkaru drink.

• Korean Journal of Materials Research
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• v.20 no.8
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• pp.444-449
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• 2010

Transparent ceramics are used in new technology because of their excellent mechanical properties over glasses. Transparent ceramics are nowadays widely used in armor, laser windows, and in high temperature applications. Silicon nitride ceramics have excellent mechanical properties and if transparent silicon nitride is fabricated, it can be widely used. h-BN has a lubricating property and is ductile. Therefore, adding h-BN to silicon nitride ceramics gives a lubricating property and is also machinable. Translucent silicon nitride was fabricated by hot-press sintering (HPS) and 57% transmittance was observed in the near infrared region. A higher wt. % of h-BN in silicon nitride ceramics does not favor transparency. The optical, mechanical, and tribological properties of BN dispersed polycrystalline $Si_3N_4$ ceramics were affected by the density, ${\alpha}:{\beta}$-phase ratio, and content of h-BN in sintered ceramics. The hot pressed samples were prepared from the mixture of $\alpha-Si_3N_4$, AlN, MgO, and h-BN at $1850^{\circ}C$. The composite contained from 0.25 to 2 wt. % BN powder with sintering aids (9% AlN + 3% MgO). A maximum transmittance of 57% was achieved for the 0.25 wt. % BN doped $Si_3N_4$ ceramics. Fracture toughness increased and wear volume and the friction coefficient decreased with an increase in BN content. The properties such as transmittance, density, hardness, and flexural strength decreased with an increase in content of h-BN in silicon nitride ceramics.