• Applied Chemistry for Engineering
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• v.8 no.5
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• pp.811-815
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• 1997

The present work describes the effect of dry grinding of a mixture composed of $Y_2O_3$, $BaCO_3$ and CuO powders with a planetary ball mill before heat treatment on crystal structure and superconductivity in the $YBa_2Cu_3O_{7-y}$. The specific surface area of the ground product of mixture decreased with an increase in the grinding time, after showing an upward trend up to 60 minutes of grinding. The critical current density, which was influenced by the grinding time of mixture, indicates the maximum value of about $150A/cm^2$ in the case of 60 minutes grinding, while the critical temperature, which were around 90K, for the sintered bodies were almost independent of the grinding time.

• Proceedings of the Korean Nuclear Society Conference
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• 2001.10a
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• pp.222.2-222
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• 2001

• Journal of the Korean Society of Food Science and Nutrition
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• v.41 no.11
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• pp.1596-1602
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• 2012

Eight rice cultivars grown in Korea were analyzed to investigate the quality of flour prepared using wet and dry grinding methods. The hardness of the kernel was related with starch damage following dry grinding but not following wet grinding. Although Chenmaai had the hardest steeped kernel, its flour exhibited minimal starch damage, a lower water absorption index (WAI), and a smaller difference between the RVA properties of wet and dry ground flour. However, Seolgan and Suweon517 are soft grains, and their flours had more starch damage and a higher WAI. In general, soft kernels produce better grinding characteristics. However, our wet grinding results indicated that grain hardness was not the main factor affecting the grinding characteristics. Even Chenmaai, with its hard kernels, had good grinding characteristics, whereas the softer kernels of Seolgan and Suweon517 did not show the appropriate grinding characteristics.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.27 no.2
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• pp.70-74
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• 2017

Two milling methods, dry vibration milling and wet ball milling, were used to prepare $Na_{2/3}(Ni_{1/3}Mn_{2/3})O_2$ powders as a cathode material for sodium ion batteries. The morphology and electrochemical property of the two powders with different milling processes were compared to each other. The particle size is less than $1{\mu}m$ in the dry vibration milled powder, while lots of larger particles than $1{\mu}m$ were found in the wet ball milled one. The single phase of $Na_{2/3}(Ni_{1/3}Mn_{2/3})O_2$ was obtained in the temperature range of $875{\sim}900^{\circ}C$. The discharge capacity and discharge voltage of the powder prepared by the dry process were higher than those of one prepared by the wet process.

• Journal of the Korean Ceramic Society
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• v.34 no.2
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• pp.195-201
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• 1997

The present paper describes the effect of dry mixed grinding on kaolinite-aluminum trihydroxide mixture with a planetary ball mill before sintering and its influence on mullite formation during sintering. The size reduction of the mixture is market in the early stage of grinding and the obtained fine particles agglomerate subsequently with an increase of grinding time. The crystal structure of the mixture is collapsed easily into an amorphous one by planetary ball milling, of which amount increases with an increase of grinding time. Only mullite phase except for anatase as an inherent impurity in kaolinite appeared in the sintered body of the mixtures with mixed grinding as relatively lower temperature 1523K, while corundum, cristobalite, and Al-Si spinel phases, besides mullite were formed in the sintered body of the mixture without mixed grinding. Therefore, the mixed grinding treatment is very effective to improve the homogeneous mixing and disp-ersion of the mixture of raw materials on a micro scale and to decrease the thermal decomposition tem-perature by crystal structure change of them so as to obatin direct preparation of mullite with high purity at relatively low temperature.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2013.05a
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• pp.211-211
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• 2013

Ru-Cr은 차세대 반도체 메모리(RAM, MRAM, FeRAM), 헤드(MR, TMR), 캐피시터의 웨이퍼 등에 전극층이나 시드층 형성을 위해 스퍼터링 타겟으로 제조되며, IT산업이 발달함에 따라 수요가 증가하고 있다. 기존의 스퍼터링 타겟은 산처리와 주조와 같은 습식법이 주를 이루었으나, 긴 제조시간과 강산사용의 위험성화 강산폐유의 처리가 문제되고 있다. 최근에는 습식공정을 보완하기 위한 건식법의 연구가 진행 중이며, 합금소재에 대한 건식법의 연구가 필요하다. 본 연구에서는 폐 Ru-Cr 금속합금 스퍼터링 타겟을 Hammer-mill, jet-mill 등 건식으로 분쇄하고 RF-Plasma를 이용하여 소결에 용이한 구형, 고순도 Ru-Cr금속합금분말을 제조하였다.

• Applied Chemistry for Engineering
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• v.18 no.1
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• pp.41-47
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• 2007

Crude copper phthalocyanine (Cupc) was synthesized by Wyler process, then grounded using various methods such as acid pasting, kneader, attritor and SC-mill. Particle size, shape and crystalline structure were compared and evaluated after particle size reductions. Cupcs prepared by acid pasting and kneader methods that are excellent manufacturing processes in industry were used as our standards. Particle properties of Cupcs prepared either by attritor or by SC-mill were compared with particle size analyzer, scanning electron microscopy (SEM) and X-ray diffraction (XRD). Particle size analyzer and SEM were used to analyze the variation of particle sizes of Cupc with milling time. Particle size was initially decreased up to the 90 min of milling time, thereafter it reversely began to increase in case of SC-mill. Cupc obtained from dry milling with attritor displayed strong cohesion so that particle size was not possible to determine with particle size analyzer. However, the optimum milling time was indirectly approximated from the analysis of XRD peak intensity.

• Journal of the Mineralogical Society of Korea
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• v.21 no.2
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• pp.129-138
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• 2008

The characteristics of beneficiating kaolin mineral by liberation (selective grinding) and air classification have been investigated, comparing the grinding rates of ball mill and impact mill. The ore was ground using a ball mill and a impact mill to evaluate the grindability of the two grinding methods based on the constant production amount of fine particles in size less than 325 mesh. Then, the fine product was further separated into two fractions using an air-classifier and each fraction was chemically analyzed to compare the beneficiation efficiency of the two grinding methods. The chemical grade of kaolin mineral decreased as increasing the grinding rate of both the mills. particularly in the case of ball mill because of overgrinding impurities such as quartz and feldspar. In the case of the ball milling, the fine fraction less than 325 mesh was air-classified at a cutting point of $43\;{\mu}m$. The production rate of the air-classified concentrate was found to be 66.2 wt%, removing 5.3% of $Fe_2O_3$ and 34.6% of CaO. Under the same conditions mentioned above with the impact mill, the production rate of the air-classified concentrate was 64.4 wt%, removing 34.2% of $Fe_2O_3$, 67.6% of CaO and 25.0% of $TiO_2$. Therefore, our results indicate that impact mill is superior to ball mill in terms of impurity removal.

• Korean Journal of Materials Research
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• v.25 no.6
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• pp.305-316
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• 2015

The study of grinding behavior characteristics on the metal powders has recently gained scientific interest due to their useful applications to enhance advanced nano materials and components. This could significantly improve the property of new mechatronics integrated materials and components. So, a new evaluation method for standardizing grinding equipment and a comparative study for the grinding experiment during the grinding process with various grinding mills were investigated. The series of grinding experiments were carried out by a traditional ball mill, stirred ball mill, and planetary ball mill with various experimental conditions. The relationship between the standardization of equipment and experimental results showed very significant conclusions. Furthermore, the comparative study on the grinding experiment, which investigated changes in particle size, particle morphology, and crystal structure of materials with changes in experimental conditions for grinding equipment, found that the value of particle size distribution is related to the various experimental conditions as a revolution speed of grinding mill and media size.

• Clean Technology
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• v.24 no.4
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• pp.332-338
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• 2018

Currently graphite is used as an anode active material for lithium ion battery. However, since the maximum theoretical capacity of graphite is limited to $372mA\;h\;g^{-1}$, a new anode active material is required for the development of next generation high capacity and high energy density lithium ion battery. The maximum theoretical capacity of Si is $4200mA\;h\;g^{-1}$, which is about 10 times higher than the maximum theoretical capacity of graphite. However, since the volume expansion rate is almost 400%, the irreversible capacity increases as the cycle progresses and the discharge capacity relative to the charge is remarkably reduced. In order to solve these problems, it is possible to control the particle size of the Si anode active material to reduce the mechanical stress and the volume change of the reaction phase, thereby improving the cycle characteristics. Therefore, in order to minimize the decrease of the charge / discharge capacity according to the volume expansion rate of the Si particles, the improvement of the cycle characteristics was carried out by pulverizing Si by a dry method with excellent processing time and cost. In this paper, Si is controlled to nano size using vibrating mill and the physicochemical and electrochemical characteristics of the material are measured according to experimental variables.