• 한국신재생에너지학회:학술대회논문집
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• 2008.10a
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• pp.149-152
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• 2008

Three properties of food waste are water 80%, ash 3%, volatile matter 17%. When food waste goes through treatment process such as removal of foreign substances, removal of water as well as sodium, dryness, and pulverization, it transforms into 4,000Kcal/kg purverized fuel if moisture content is below 13%. Fuel ratio(fixed carbon/volatile matter) of purverized fuel is low compared with bituminuous coal. Ignition temperature measured by thermogravimetry analyzer is about $460^{\circ}C$. Combustion test of purverized fuel have been performed using energy recovery facility which include storage tank of dewatered cake, dryer, hammer mill, combuster including burner, boiler, flue gas treatment equipment. When 160-180 kg/hr of fuel is steadily supplied to burner for 3 hours, combueter temperature reaches about $1000^{\circ}C$ and CO is 77-103ppm at 1.55 excess air ratio and SOx and Cl are under 2ppm and 1ppm, respectively. This experiment demonstrate that purverized fuel made from food waste could be an alternative clean energy for high oil price era

• Journal of the Korean Ceramic Society
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• v.28 no.1
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• pp.46-52
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• 1991

The hydroxyapatite powders were prepared by the reaction of Ca(CH3COO)2$.$H2O and H3PO4 in aqueous solution. Effect of Ca/P mole ration and pH value on the powder characteristics were investigated. For phosphoric acid was dissociated to PO43- ion above pH 10, the preparation condition of hydroxyapatite by H3PO4 solution had this value. Dried powders were agglomerated each other. The mean agglomerate particle diameter was minimum when the condition was pH 11, Ca/P=1.75 and its specific surface area was 97㎡/g. All powders had poor crystallinity and small CO2. It prevented CaCO3 from using aspirator in preparation and maturing time. In most cases, hydroxyapatite was decomposed into ${\beta}$-TCP at more than 800$^{\circ}C$, into ${\alpha}$-TCP at 1200$^{\circ}C$. However non-decomposed hydroxyapatite was remained in Ca/P=1.85.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2013.11a
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• pp.68-71
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• 2013

Reactive Powder Concrete (RPC) is an ultra high strength and high ductility cement-based composite material and has shown some promise as a new generation concrete in construction field. It is characterized by a silica fume-cement mixture with very low water-binder (w/b) ratio and very dense microstructure, which is formed using various powders such as cement, silica fume and very fine quartz sand (0.15~0.4mm) instead of ordinary coarse aggregate. However, the unit weight of cement in RPC is as high as 900~1,000 kg/㎥ due to the use of very fine sand instead of coarse aggregate, and a large volume of relatively expensive silica fume as a high reactivity pozzolan is also used, which is not produced in Korea and thus must be imported. Since the density of RPC has a heavy weight at 2.5~3.0 g/㎤. In this study, the modified RPC was made by the combination of ternary pozzolanic materials such as blast furnace slag and fly ash, silica fume in order to economically and practically feasible for Korea's situation. The fire resistance and structural behavior of the modified RPC exposed to high temperature were investigated.

• Journal of the Korean Ceramic Society
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• v.29 no.8
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• pp.667-673
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• 1992

The alumina-zirconia composite powders of core particle ZrO2 coated with Al2O3 were prepared by the hydrolysis-deposition of the mixed aluminum salt solution of Al2(SO4)3-Al(NO3)3-Urea. The effects of hydrolysis reaction and coating parameters on characteristics of coated powders and composites were also investigated. The degree of coating could be estimated from the ratio of tetra-/mono-ZrO2 present at the room temperature after heat-treating coated powders at 120$0^{\circ}C$ and the result of TEM observations. When the content of ZrO2 in the dispersed coating system, the coating time, and the volume ratio of water/solution were 50 mg/g, 180 min, and 5, respectively the coating efficiency was maximum (the ratio of tetra-/mono-ZrO2 was 87/13). The relative densities of coated Al2O3-ZrO2 composites sintered at 1$650^{\circ}C$ for 4 hrs were about 91~98% and the maximum ratio of tetra-/mono-ZrO2 in Al2O3-20wt% ZrO2 composites was 62/38.

• Korean Chemical Engineering Research
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• v.60 no.2
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• pp.229-236
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• 2022

An experimental investigation was conducted on the influences of median size, dust concentration, dust condition (cloud and layer) for the fire and explosion hazard assessment of dusts with the same powder property. For this purpose, tests have been performed in accordance with 20 L explosion sphere, thermogravi- metric analyze, combustion rate tester (UN method). We investigated the explosion characteristics and flame propagation velocity (FPV) in dust cloud and the flame spread velocity(FSV) over dust layer on 8 dust samples with different particle sizes of 4 types of dusts (Sugar, Mg, Al, Zr). An explosion hazard increased with decreasing particle size in Mg and Al dust clouds, but sugar did not show the effect of explosion hazard due to particle size change in dust clouds. The flame propagation velocity (FPV) of suspended dusts increased significantly when the particle size decreased from micro to nano than the variation of particle size in micro range. The flame spread velocity (FSV) over dust layer showed a tendency to increase over the inclined dust layers (30° slope) rather than the horizontal dust layers (0° slope). The flame spread rate (FSV) over dust layers increased on the inclined dust layer (30° slope) rather than the horizontal dust layer (0° slope) and was higher upward flame than the downward flame in condition of inclined dust layers(30° slope).

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.35 no.12
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• pp.165-172
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• 2019

The aim of the research is to evaluate the influence of various replacing ratios of supplementary cementitious materials(SCMs) such as fly ash(FA), blast furnace slag(BS), and both FA and BS on general properties including segregation resistance as a powder based high fluidity concrete of normal strength grade with water-to-cement ratio 0.40. Specifically, by replacing the SCMs with low density powders, it was assessed that the decreased segregation resistance due to the decreased viscosity by J-ring test. As a result of the experiment, from the general test, the mixtures with SCMs showed increased segregation resistance by increased viscosity as the references, while some segregation was shown from J-ring test due to the decreased density of fresh state mixture related with the capacity of delivering coarse aggregate.

• Proceedings of the KSEEG Conference
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• 2001.04a
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• pp.308-310
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• 2001

유기물질이 오랜 기간동안 고온 고압하에서 탄화작용을 받아 생성된 천연흑연은 단위구조가 탄소육각망평면(炭素六角網平面)이 평행하게 배열된 층상으로 전기전도도 및 윤할성이 우수하나 소수성이 매우 강하며 표변화학적 특성이 거의 없기 때문에 다른 물질과 표면흡착이 매우 어려운 물질이다. 따라서 본 연구에서는 흑연의 표면특성을 변화시키고자 유기물(ABDM)을 흡착시키고 표면흡착 매커니즘 및 표면특성을 해석하였다. 흑연 입자 표면 위의 ABDM흡착은 두 단계의 서로 다른 게에서 이루어졌다. 첫 번째 단계는 흡착 초기 흑연입자와 ABDM의 표면전위 특성차이에 의한 1차 흡착으로 흑연표면 소수성이 더욱 증가하는 상태이고, 두 번째 단계는 1차 흡착된 ABDM 과 용액중의 ABDM chain 상호간의 steric 작용에 의한 2차 흡착이었다. 2차 흡착이 완료된 흑연입자 표면은 ABDM 이중층을 형성하게 되고 이에 따라 흑연의 표면전위 특성을 변화시킬 수 있었다.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 1999.06a
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• pp.237-242
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• 1999

산업이 고도화되고 다양화됨으로써 그로 인한 대형사고의 발생위험은 계속 커져가고 있으며, 아울러 분진에 의한 재해의 위험이 커지고 있다. 최근에는 플라스틱 공업, 유기합성 공업, 분말금속 공업, 식료품 공업, 사료 공업 및 제약 산업 등에서 기술의 진보에 따라 원료ㆍ제품을 취급하는 공정이 많아졌으며, 이와같은 분체 취급분야의 확대, 취급량의 증대, 공정의 연속화, 생산속도의 가속화의 경향은 분진폭발의 잠재 위험성을 증대시키는 결과를 초래했다. (중략)

• Journal of the Korean Ceramic Society
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• v.33 no.10
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• pp.1147-1155
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• 1996

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 1998.11a
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• pp.105-108
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• 1998

Dust explosion은 combustible solid의 미세한 입자가 공기 혹은 산소중에서 폭발범위의 농도에서 부유할 때 화염 혹은 spark 등의 에너지 공급에 의해 폭발하는 현상이며 plastic 공업, 금속분말, 유기약품, 무기약품, 안료, 농수산건조물 등에서 분체취급 분야의 확대 및 취급량의 증가에 따라 분진폭발의 잠재 위험성이 급증하고 있어 화학적 성질, 농도, 입경, 폭발 압력 등의 분진특성과 함께 분진폭발의 착화온도와 상한 및 하한 농도에 대해 이론 및 실험적으로 광범위하게 연구가 진행되어져 왔다. (중략)