• Applied Chemistry for Engineering
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• v.19 no.3
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• pp.264-269
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• 2008

For the synthesis of lead chromate pigments, we investigated the characteristics of particle growth with reacting conditions in the synthetic process, the effect of additives, and its micro-capsulation. The more tiny and uniform dispersion particles could be obtained at a lower pH and diluter intial concentration. The variation range of average pigment size was increased with the agitating speed. The pigment size could be controlled by adding aluminum sulfate as an additive, which maintained the optimum particle dispersion. It was found that the optimum micro-capsulation conditions were pH 9~10 and above $90^{\circ}C$ during the micro-capsulation of lead chromate pigment, and below 0.5% humidity after micro-capsulation.

• Resources Recycling
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• v.28 no.2
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• pp.23-30
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• 2019

An color sorting technique was introduced to recycle End-of-life automobile shredded bumpers. The color sorting is a innovate method of separating the differences in the color of materials which are difficult to separate in gravity and size classification by using a camera and an image process technique. Experiments were planned and optimal conditions were derived by applying BBD (Box-Behnken Design) in the reaction surface method. The effects of color sensitivity, feed rate and sample size were analyzed, and a second-order reaction model was obtained based on the analysis of regression and statistical methods and $R^2$ and p-value were 99.56% and < 0.001. Optimum recovery was 94.1% under the conditions of color sensitivity, feed rate and particle size of 32%, 200 kg/h, and 33 mm respectively. The recovery of actual experiment was 93.8%. The experimental data agreed well with the predicted value and confirmed that the model was appropriate.

• Journal of the Korean Society of Propulsion Engineers
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• v.20 no.3
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• pp.25-31
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• 2016

This research investigated the manufacturing process and characteristics analysis of ZPP(Zirconium Potassium Perchlorate) as pyrotechnic are commonly found in the aerospace, defense, and automotive industries. A solid pyrotechnic mixture is composed of an oxidizing agent, fuel, and binder. Precipitation process was used to uniformly mix the raw material. Through the analysis of the material characteristics and thermal response is designed optimum ratio by NASA CEA program. It was compared by performing the evaluation of these size, shape and calorimetry characteristics.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2002.11a
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• pp.165-169
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• 2002

BaTiO$_3$ 분말을 Ba(OH)$_2$ㆍ8$H_2O$와 아나타제형의 TiO$_2$ㆍ$\chi$$H_2O$를 이용하여 광화제 첨가 없이 열수처리에 의한 탈수(dehydration) 및 재결정화(recrystallization) 과정을 통한 수열합성법에 의해 제조하였다. Autoclave 반응기를 이용한 실험의 경우, BaTiO$_3$ 분말을 생성하기 위한 최적 반응온도 및 시간은 각각 21$0^{\circ}C$, 4시간으로 확인되었으며, 이 때 생성된 BaTiO$_3$ 분말의 크기는 0.1~0.2$mu extrm{m}$로 입도분포가 양호하였다. 그리고, 바륨과 티타늄의 농도비가 증가됨에 따라 결정화도(tetragonality)가 증가하는 경향을 나타내고 있다. 이는 반응하지 않고 남아 있는 바륨의 영향으로 생각되며, 이는 반응물의 pH와도 관련이 있다. 또한, 반응온도 및 시간도 결정화도에 커다란 영향을 미치는 변수로 주로 반응온도 및 시간이 증가함에 따라 결정화도도 함께 증가하는 추세를 나타내고 있다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.7 no.2
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• pp.292-300
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• 1997

PSZT powders having the particle size of 0.5~5 $\mu\textrm{m}$ with cubic shapes, were prepared by a hydrothermal reaction in the temperature range of 150~$^{\190circ}C$ for a 2 h reaction. Experimental results showed that as the reaction temperature increased, the nucleation and crystal growth were accelerated and the the particle size became larger. However, the particle size became smaller with its narrow distribution as the concentration of a mineralizer (KOH) increased. It was possible to reduce the reaction temperature by increasing mineralizer concentrations. With increase in Zr/Ti ratio, the major crystal phase of synthetic PSZT powders was seen to change from tetragonal phase to rhombohedral phase.

• Geotechnical Engineering
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• v.11 no.2
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• pp.107-120
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• 1995

The purpose of this study is to investigate the effects of fiber on engineering properties of Fiber-Reinforced Soil. Engineering properties of soil reinforced with discrete randomly oriented inclusion depend on soil density, particle size, grading, fiber length, tensile strength and stiffness of fiber, mixing ration of fiber, confining stress, etc.. in this paper, the influence of fiber shape, fiber length, fiber diameter, fiber content, cement content and curing duration on engineering characteristics(compaction, shear & permeability) were evaluated for typical soils produced from construction works through uniaxial compression tests and triaxial compression tests. From the experimental results, it was also investigated if there is an optimal range of fiber lengths and fiber contents for the tested soils and tested mono-filament fibers.

• Resources Recycling
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• v.2 no.2
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• pp.39-44
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• 1993

This study was carried out to remove the water from low grade anthracite slurry produced at Eoryong coal mine by the oil agglomeration process. 80% of Anthracite as a coal oil mixture (COM) was separated from water by the difference of specific gravity. Then, the amount of kerosene, diesel oil, and heavy oil forming COM was 10% of the amount of sample, respectively. The recovery rate of combustibles and ash content of agglomerated anthracite were affected largely by the amount of added oil, pulp density, particle size, mixing time, and impeller speed. The recovery rate of combustibles was increased to 95% and ash content was decrea-sed from 30% to 13.5% under the optimum conditions.

• Resources Recycling
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• v.11 no.6
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• pp.24-30
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• 2002

Reduced and modified converter slag was ball milled and sieved to -200/+325 mesh. CaO,$SiO_2$, $Fe_2$$O_3$ was added to slag powder and mixed to make it similar to the composition of normal portlant cement. The pellet made of this powder was heated from $1250^{\circ}C$ to $1450^{\circ}C$ for 15 min～45 min. Most feasible condition for making slag cement clinker is the heating more than 20 min at $1450^{\circ}C$. The compressive strength of the mortar made of this slag cement clinker was better than that of normal port-lant cement in long time curing.

• Resources Recycling
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• v.6 no.4
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• pp.31-37
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• 1997

The Mg-ferrite powders were recovered from acid leaching Mg waste by hydrothermal method. Recovering conditions ofMg-Ferrite were investigated m this system and the powders prepared were characterized, using X-ray analysis, chemicalanalysis, SEM. TEM, and VSM. In this study, pH of solution and the kind of neutralizer wcre important factors on thecharacteristics of the product. The optimum condition of recovering MgPenite was the mole ratio of Fe" : Mg"=2'1, reactiontemperature : ZOWC, reaction time.lhr, at pH=lZ, and Oi partial pressure af 2000 psi. And the powders ~ccovered have amonodispersed and spherelike shapes with the narrow sue distribulion.ow sue distribulion.

• Resources Recycling
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• v.12 no.2
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• pp.36-44
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• 2003

The present work relates to the recovery of dissolved Mo from spent mandrel dissolving acid solution by injecting ammonia gas. In order to optimize the process parameters for high yield and high purity of recovered Mo products, a bench scale and a pilot scale experiments were carried out. As a result, more than 99.5% of Mo in spent acid was recovered in the form of ammonium molybdate(4MoO$_3$.$2NH_3$.$H_2$O). The purity of Mo products recovered was higher than 99.5%. In addition, the mother liquor, residual solution after precipitation and filtration of ammonium molybdate solid particles, could be utilized as fertilizers.