• Journal of Welding and Joining
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• 제15권1호
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• pp.116-124
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• 1997

A scope of this study is to establish the optimum plasma spray conditions for fine ($5\mu\textrm{m}$) $Al_2O_3$ powder. However, the flowability of the $Al_2O_3$ powder is not so good because of irregular particle shape and fine particle size. Therefore, powder feeding system was modified by 1) change of powder feeding line material from polymer to copper 2) shorten the powder feeding tube length 3) heating the powder feeding system to $80^{\circ}C$4) vibrating the powder feeding line continuously, in order to feed the fine powder homogeneously. The homogeneous powder feeding conditions were obtained with the modified powder feeding system by controlling the powder carrier gas flow and the powder flow rate indicator. The best plasma spraying conditions for the fine $Al_2O_3$ powder were found out as 40kw gun power, 80 g/min. powder feed rate and 50 mm working distance after characterizing the microstructure, hardness and wear loss of the $Al_2O_3$ coating layer.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 1998년도 공동 심포지엄 및 추계학술발표회
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• pp.97-105
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• 1998

The goal of this study is to investigate the potential application of triboelectrostatic separation process for removing unburned carbon from fly ash. The process utilizes the difference in electrical charging characteristics between the organic material (carbon) and the mineral matter (fly ash). In the present work, dry separation tests have been conducted on Samchunpo fly ash samples using a bench - scale analytic separator. The test variables studied include air rate, feed rate, electric field strength, particle size, charger material and length, etc. The best separation results were obtained at the air rate 501/min, feed rate 15 g/min and voltage 15 ㎸. The fly ash with carbon content below 1 % was obtained with over 65% recovery.

• 산업기술연구
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• 제15권
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• pp.175-185
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• 1995

Under the new environmental regulations announced by the government, utilities will have to cut their sulfur dioxide emissions by 60% from 1991 levels by the year of 1999. Sulfur dioxide emissions can be reduced prior to combustion by physical, chemical or biological coal cleaning. The new technology of high gradient magnetic separation (HGMS) offers the potential of economic separatoins of a variety of fine, weakly magnetic minerals including inorganic sulfur and many ash-forming minerals from coals. In the present paper, magnetic separation tests have been conducted on Korean anthracite and high-sulfur Chinese coal to investigate the feasibility of these techniques for reducing sulfur content from coals. In wet magnetic separation, the studied operating parameters include particle size, pH, matrix types, feed solids content, feed rate, number of cleaning stages and etc. The results shows that for wet separation, 60~70% of total sulfur was removed from coals with over 80% combustible recovery, on the other hand, for dry separation, 47.6% of total sulfur was removed from coals with 75% recovery.

• 한국환경과학회지
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• 제1권2호
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• pp.105.1-113
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• 1992

The present study was performed to develop the removal system of the offensive gases, including hydrogen sulfide of acid gas, ammonia or amice of base gas, from the nightsoil treatment plant. In order to remove the offensive gases, the Fe-EDTA system liquid phase catalytic oxidation method with the bubble lift column reactor was employed. From the results obtained, it was confirmed that the offensive gases can be deodorized simultaneously and also hydrogen sulfide of acid gas, ammonia of base gas completely removed at pH 6.45. In addition, as input gases feed rate the efficiency of acid gas did not change but the efficiency of base gases decreased to approximately 90 % at pH 6, 0. From the result of particle size analyzer, it was found that the particle sizes including sulfur and other impurites grew up to $21{\mu}m$ over 72hour reaction time.

• Journal of Advanced Marine Engineering and Technology
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• 제28권5호
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• pp.773-781
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• 2004

This research was Performed to raise grade efficiency of Sturtevant type air classifier. to treat powder less than $74\mu\textrm{m}$ particle produced at the crushing process of the dry aggregates manufacturing system or concrete wastes recycling system. The experimental conditions were in the ranges. 0.85 to 5.15 $m^3$/s of primary air flow rate. 0.005 to 0.015 $m^3$/s of secondary air flow rate $30^{\circ}$ to $70^{\circ}$ of auxiliary blades angle. respectively. for 1.7~3.3 kg/min of the powder feed rate. It was found that the grade efficiency of the air classifier was increased as the baffle plate was attached at the expansion region. and the optimal operating conditions of the air flow rates and the blade angle were obtained. The fractional recovery curves from the experiments were well agreement with the theoretical one of Molerus model.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.2423-2428
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• 2008

A turbo classifier having a rotating rotor of two stage classification region has been developed to have a cut size of 1 micro meter. Particle number concentrations were counted using Aerosol Particle Sizer (APS, TSI co., USA) at inlet and outlet of the classifier. Partial classification efficiency was obtained at various rotation speeds, total flow rates, and feed rates of powders, and classification characteristic depending on design parameters was discussed. Classification performance was enhanced as rotation speed of rotor increased and total flow rate decreased.

• 한국축산식품학회지
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• 제41권5호
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• pp.855-868
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• 2021

The present study was designed to investigate the effects of protein formula with different casein (C) to whey protein (W) ratios on dispersion stability, protein quality and body composition in rats. Modification of the casein to whey protein (CW) ratio affected the extent of protein aggregation, and heated CW-2:8 showed a significantly increased larger particle (>100 ㎛) size distribution. The largest protein aggregates were formed by whey protein self-aggregation. There were no significant differences in protein aggregation when the CW ratios changed from 10:0 to 5:5. Based on the protein quality assessment (CW-10:0, CW-8:2, CW-5:5, and CW-2:8) for four weeks, CW-10:0 showed a significantly higher feed intake (p<0.05), but the high proportion of whey protein in the diet (CW-5:5 and CW-2:8) increased the feed efficiency ratio, protein efficiency ratio, and net protein ratio compared to other groups. Similarly, CW-2:8 showed greater true digestibility compared to other groups. No significant differences in fat mass and lean mass analyzed by dual-energy x-ray absorptiometry were observed. A significant difference was found in the bone mineral density between the CW-10:0 and CW-2:8 groups (p<0.05), but no difference was observed among the other groups. Based on the results, CW-5:5 improved protein quality without causing protein instability problems in the dispersion.

• 자원리싸이클링
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• 제33권3호
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• pp.38-47
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• 2024

몰리브데나이트는 몰리브덴의 주요 광물자원으로 고유의 소수성 표면으로 인해 부유선별을 통해 회수된다. 한편, 채광되는 몰리브데나이트의 결정크기 및 품위가 낮아지고 있다. 이로 인해, 단체분리에 요구되는 광물 크기가 작아짐으로써, 부유선별에 투입되는 원광 크기 또한 미립화되고 있다. 미립자는 기포와의 충돌확률이 낮아, 부유선별할 때 효율 감소를 유발시킨다. 이에 따라, 몰리브덴 확보를 위해서는 미립 몰리브데나이트에 대한 부유선별 연구가 필요한 실정이다. 본 연구에서는 5-30 ㎛의 미립 몰리브데나이트의 부유선별 효율을 향상시킬 수 있는 방안을 제안하였다. 기포크기 축소와 입자응집을 통한 효율 증진으로 접근하였다. 기포-입자 충돌확률을 시뮬레이션과 부유선별 실험을 통해, 미립자의 부유선별 효율이 향상될 수 있는 기포크기 및 입자응집체 크기에 대한 범위를 정량적으로 결정하였다. 결과적으로 본 연구에서 제공한 미립 몰리브덴광 부유선별 조건은 향후 몰리브덴 선광 플랜트의 부유선별 공정을 향상시키는 데 활용될 예정이다.

• 한국재료학회지
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• 제4권7호
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• pp.808-816
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• 1994

본 연구에서는 안정제를 이용하는 반회분식 분산 중합(semi batch dispersion polymerization)공정으로 전도성 고분자인 p-Doped polypyrrole 입자를 제조하였다. 반회분식 분산 중합은 단량체를 monomer starved 조건하에서 연속 주입하여 중합시키는 방법으로써 polyvinylalcohol(PVA)을 안정제로 사용한 경우 평균 50nm, methylcellulose를 안정제로 사용한 경우평균 95nm 정도의 입자 크기를 갖는 dispersion을 제조할 수 있었으며, 이의 입자 크기 및 전도도는 단량체 투입 속도, 개시제 농도와 안정제의 종류, 분자량 및 농도에 따라 변화하였다. 이는 도입 성분중 개시제와 안정제의 역할(친수성 정도, 분자량)에 따라 달라지는 것으로, 이에 따른 물성의 최적점을 찾을 수 있었다.

• Journal of Animal Science and Technology
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• 제45권5호
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• pp.813-818
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• 2003

본 시험은 자가제조 TMR 농가의 TMR 배합기 운용실태와 국내에서 생산 이용되고 있는 TMR을 대상으로 TMR 배합소에서 생산되는 20개 유통 TMR과 농가에서 직접 제조하여 이용하는 20개 자가 TMR의 입자도를 Penn State Particle Size Separator를 이용하여 측정하여 TMR 입자도의 분포를 측정한 결과, 자가 TMR 배합기를 이용하여 TMR을 제조하는 농가의 1일 총 배합에 소요되는 시간은 48.6${\pm}$28.0분으로 나타났으며, 자가 TMR 농가의 보유 배합기 형태는 2오거가 55.5%로 가장 많았고, 여름철 및 다른 계절에 1일 2회 배합하는 농가가 44.4 및 22.2%였다. 자가 TMR 농가의 배합기 가동시간별 상위 체에 남아 있는 비율이 21.5~25.6%, 중간 체에 남아 있는 비율이 16.0~25.8% 그리고 바닥 체에 남은 사료의 비율은 52.8~61.4%로 많은 차이가 있었다. 자가 및 유통 TMR의 입자 길이가 19mm 이상인 사료의 비율이 각각 24.9${\pm}$1.4 및 26.2${\pm}$1.7%, 입자 길이가 8~19mm미만인 사료의 비율이 각각 22.8${\pm}$1.0 및 12.8${\pm}$1.2% 그리고 입자 길이가 8mm 미만인 사료의 비율이 52.3${\pm}$1.7 및 61.0${\pm}$1.5%였다. 이는 자가 TMR과 유통 TMR 모두에서 8~19mm미만 범위에 있는 입자는 Penn State Separator에서 추천하는 비율보다 각각 82.6%, 100%가 낮은 것으로 나타났는데, 이는 전체적으로 국내에서 생산 이용되고 있는 TMR의 입자도가 긴 것과 짧은 것의 적절한 조화가 이루어지지 않고 있음을 알 수 있다. 따라서 TMR을 급여하고 있는 농가에서 TMR중 입자도가 적정한지를 평가하기 위한 가장 기본적인 일은 우군의 반추행동을 모니터링하는 일이다. 즉, 전체 우군중 사료를 섭취하고 있는 소를 제외하고 휴식중에 있는 소들중 반추를 하고 있는 소가 40%가 안된다면 전체적으로 입자도가 너무 적거나 조사료의 비율이 너무 낮지 않은지 검토하여 배합시간을 조정하거나 배합비를 재조정해 주어야 할 것이다.