• Korean Journal of Materials Research
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• v.8 no.7
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• pp.596-600
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• 1998

Reaction bonded $AI_2O_3$(RBAO)-SiC ceramics were prepared from the Al/$AI_2O_3$/SiC powder mixture. The calcined alumina and fused alumina were used as the raw $AI_2O_3$ powder. The same sized (3mm) and differently sized (3mm + Smm) $Zr0_2$ balls were used in attrition milling of starting powders. The effect of $AI_2O_3$ powder shapes on the milling efficiency and reaction sintering was investigated. After attrition milling, isopressed compacts were preheated to 1l00$^{\circ}$C with a heating rate l.5$^{\circ}C$/min and then sintered at the temperature range 1500 to 1$600^{\circ}C$ for S hours with a heating rate 5$^{\circ}C$/min. The powder mixture with fused alumina was effectively comminuted than the mixtures with calcined alumina. And the same sized balls milled more effctive than the differently sized balls. The reaction sintering behavior differed not depending on the shapes of $AI_2O_3$ powder.

• Journal of the Korean Geotechnical Society
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• v.26 no.2
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• pp.55-62
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• 2010

This paper investigates the shear properties of waste tire-bottom ash mixture with various particle size of waste tire powder. Test specimens were prepared at 5 different percentages of waste tire powder content (i.e., 0%, 25%, 50%, 75%, 100% by weight of the dry bottom ash), and with three different particle sizes of waste tire powder (i.e., 0.1 mm~2.0 mm, 0.9 mm~5 mm and 2 mm~10 mm). In this study several series of direct shear tests were carried out. The experimental results indicate that the mechanical characteristics of waste tire-bottom ash mixture are strongly influenced by the particle size as well as waste tire powder content. It is shown that the shear strength and internal friction angle of waste tire-bottom ash mixture decrease with an increase in waste tire powder content. However, the shear strength and internal friction angle of the mixture increase due to interlocking effect between waste tire powder and bottom ash as the particle size of waste tire powder increases.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.4C
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• pp.247-253
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• 2008

This paper investigates the mechanical characteristics of waste tire powder-added lightweight soil in which dredged soils, waste tire powder and bottom ash were reused. In this study, 5 groups of soil samples were prepared with varing contents of waste tire powder ranged from 0% to 100% at 25% intervals by the dredged soil weight. The mixed soil samples were subjected to unconfined compression and elastic wave tests to investigate their unconfined compressive strengths and dynamic properties. Test results showed that the unconfined compressive strength and unit weight decreased as the waste tire powder contents increased, but axial strain at failure increased. Also stress-strain relationship of waste tire powder-added lightweight soil showed a ductile behavior rather than a brittle behavior. The result of elastic wave tests indicated that the higher waste tire powder content, the lower elastic wave velocity and the lower shear modulus (G).

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2000.04a
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• pp.42-42
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• 2000

• Korean Journal of Materials Research
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• v.4 no.2
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• pp.213-218
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• 1994

제올라이트 분말을 기본재료로 하는 전기유변유체의 전기 및 유변학적 특성이 연구되었다. 전기장 인가시 높은 한계응력을 얻기 위하여 비교적 유전상슈가 큰 5종류의 유전유체를 선택하여 제올라이트 분말과 혼합하여 전기유변유체를 준비하였다. Couette형 rheometer를 이용하여 유변유체의 한계응력을 인가된 전기장 및 온도의 함수로서 측정하였다. 이중 chlorinate hydrocabon oil과 제올라이트 분말을 혼합한 전기유변유체의 한계응력은 6KPa(E=4KV/mm, T=$25^{\circ}C$)로서 최대치를 기록하였다. 측정된 한계응력은 온도가 상승하면 점차 감소하는 반면 전류밀도는 온도에 따라 증가하였다. 전류밀도에 대한 Arrhenius 그라프에서 전기전도에 대한 활성화 에너지는 약 0.7eV였으며 이는 제올라이트 분말에 포함된 $Na^{+}$ 이온의 확산에 기인하는 것으로 분석되었다.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 1994.10b
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• pp.18-18
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• 1994

• Journal of the Korean Wood Science and Technology
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• v.12 no.1
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• pp.3-10
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• 1984

Taro-UF mixed type resin system was developed for gluing plywoods. The taro adhesive that was activated with sodium hydroxide was mixed with the definite ratios of UF resin adhesive. At the sametime, wheat-UF mixed type resin was also applied with the same method as taro-UF mixed type resin The mixing ratios of taro or wheat adhesive: UF resin were 0:100, 10:90, 20:80, 30:70, 40:60, 50:50, 60:40, 80:20, and 100:0 by weight. In addition, the UF resins extended with wheat powder at the extending ratios of wheat powder UF resin, 10:90, 20:80, 30:70, 40:60, and 50:50 by weight, were also used. The dry and wet shear strengths of the plywoods of 30:70 (taro adhesive : UF resin) mixing ratio were highest. The dry shear strengths of the plywoods manufactured with the UF resin-mixing taro adhesive were higher than those of the plywoods with the UF resin-mixing wheat adhesive at 10:90, 20:80, 30:70, 40:60, 50:50, and 60:40 (taro or wheat adhesive: UF resin) mixing ratios. At all mixing ratios, the wet shear strengths of the plywoods manufactured with the UF resin-mixing taro adhesive were higher than those of the plywoods with the UF resin-mixing wheat adhesive. The dry and wet shear strengths of the plywoods manufactured with the UF resin-mixing wheat adhesive were higher than those of the plywoods with the wheat powder-extending UF resin at the mixmg ratios, 10:90, 20:80, 30:70, and 40:60 (wheat adhesive or wheat powder: UF resin). So, it was found that the plywoods manufactured with the UF resin-mixing taro adhesive and the UF resin mixing wheat adhesive had better shear strength than the plywoods with the wheat powder-extending UF resin. It was because the taro adhesive and wheat adhesive themselves took the bonding properties after being activated with alkali.

• Proceedings of the Korean Nuclear Society Conference
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• 1995.05a
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• pp.747-752
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• 1995

핵융합로 증식재용 ${\gamma}$-LiAlO$_2$ 분말을 자발착화 연소반응법을 적용하여 합성하였다. LiAlO$_2$분말을 합성하는데 이 방법을 적용하면 다른 분말 합성법과 달리 짧은 시간 내에 미세한 ${\gamma}$상을 쉽게 형성할 수 있었다. 최적의 ${\gamma}$-LiAlO$_2$ 분말을 합성하려면 구연산과 우레아의 혼합연료가 가장 적절하다고 판단되며, 이 연료로 합성된 ${\gamma}$-LiAlO$_2$ 분말을 24시간 볼분쇄하면 비표면적 값이 15.8 m$^2$/g인 미세한 분말을 얻을 수 있었다.

• The Korean Journal of Food And Nutrition
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• v.17 no.1
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• pp.8-17
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• 2004

The effect of chlorella extract on the growth and acid production of yoghurt starter was investigated in order to prepare the yoghurt added with chlorella extract. The various levels of chlorella extract powder were added to skim milk medium and the medium was fermented by single or mixed culture of 4 types of lactic acid bacteria such as Streptococcus thermophilus, Lactobacillus acidophilus, Lactobacillus casei, and Lactobacillus bulgaricus. The changes in acid production(pH, titratable acidity) and number of viable cells of the medium during fermentation in skim milk added with chlorella extract powder have determined. When chlorella extract powder was added to skim milk medium at the levels of 0.5%, 1.0%, 2.0%, and 3.0%, the addition of 0.5% chlorella extract powder with the single culture of Str. thermophilus, Lac. casei, and Lac. bulgaricus showed the highest number of viable cell counts after 9 hours incubation. And also all single cultures of the yoghurt starter produced the higher amounts of acid with the addition of 0.5% chlorella extract powder. When chlorella extract powder was added to the medium at the levels of 0.25%, 0.5%, 1.0%, and 2.0%, the addition of lower lever(0.25∼0.5%) of chlorella extract powder with the mixed culture of the lactic acid bacteria showed more the acidity of pH and the number of viable cell counts. Among the treatments tested, the addition of 0.25% chlorella extract powder with the mixed culture of Str. thermophilus and Lac. casei produced the highest number of viable cell counts after 12 hours incubation. Therefore it was suggested to manufacture the yoghurt with the addition of 0.25% chlorella extract powder and the inoculation of mixed culture of Str. thermophilus and Lac. casei for on the stimulation of growth of the yoghurt starter.

• Journal of the Korea Concrete Institute
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• v.18 no.4 s.94
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• pp.517-526
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• 2006

In this study, in order to utilize waste concrete powder(WCP) which is occurred in manufacturing high quality recycled aggregate as an admixture for self-compacting concrete(SCC), the properties of cement paste, mortar, and concrete that were mixed two types of WCP, 928 and 1,360 $cm^2/g$ of surface area, were analyzed. As a result of experiment, we have found that WCP was a porous material with angle. When WCP was utilized as an admixture for SCC, its flowability and viscosity increased in proportion to the increase of a replacement ratio, and that a replacement ratio of WCP was proper within 15%. The compressive strength at 28 days mixed respectively with WCP2, 15 and 30%, showed about 36 and 28 MPa, and it showed a similar trend with a function suggested in CEB-FIP for the relationship of compressive strength and elastic modulus. According to the results, it is judged that WCP2 can be utilized as an mineral admixture of normal strength SCC.