• 약학회지
• /
• 제18권4호
• /
• pp.236-242
• /
• 1974

Extrusion-spheronization processing combination was used to produce spherical granules with experimental formulations which contain microcrystalline cellulose as a diluent. The produced granules were compared on the basis of the following physical properties ; (a) bulk density, (e) porosity, (f) friabillity and (g) dissolution rate. With the specific experimental formulations used in this study, the increased plate rotational speeds of Marumerizer (400-1200rpm) produced continually more spherical material and also the obtained data indicated that the particle size distribution and dissolution rate depend upon the amount of microcrystalline cellulose used. As a result, the spherical granule preparation with microcrystalline cellulose has good properties in flow rate, packing propertyu and friability and offers a suitable method of granule preparation in pharmaceutical industry.

• 공업화학
• /
• 제22권6호
• /
• pp.631-635
• /
• 2011

직접산화법으로 제조한 구형 실리카졸과 비구형 실리카졸의 입자크기와 형상에 따른 산화막의 기계화학적 연마율에 미치는 영향을 연구하였다. 구형 실리카졸은 금속 실리콘 분말로부터 직접산화법에 의해 10~100 nm까지 크기별로 제조하였다. 직접산화법으로 제조한 10 nm 크기의 실리카졸에 산, 알콜, 실란과 같은 응집유도제에 의한 첨가하여 입자간 응집을 유도한 시드 졸을 제조하고, 여기에 실리콘 분말과 알칼리 촉매를 투입하여 직접산화법으로 입자를 성장하여, 두 개 이상의 입자가 응집되어 있는 실리카 시드의 형상이 유지된 상태에서 성장한 응집 비구형 실리카졸을 제조하였다. 이를 산화막 CMP에 적용하여 구형 및 비구형 실리카졸의 입자형상 및 크기에 따른 연마율을 비교하였다. 구형 실리카의 경우, 입자크기가 증가할수록 연마율은 높아졌고, 비구형 실리카졸은 평균입경이 유사한 크기의 구형 실리카 보다 더욱 높은 연마율을 나타내었다.

• 대한기계학회논문집A
• /
• 제38권9호
• /
• pp.1037-1041
• /
• 2014

반도체 연마용 슬러리를 이온교환법, 가압방법 및 다단계 주입방법으로 제조하여 입자 크기와 형상에 따른 화학적 기계적 연마에 미치는 영향을 연구하였다. 이온교환법을 이용하여 구형의 콜로이달실리카를 크기별로 입자로 제조하였다. 이렇게 제조한 구형의 실리카를 다시 가압방법을 이용해 입자간의 결합을 유도해 비구형의 형상을 가진 콜로이달 실리카를 제조하였고, 이온교환법과 가압방법의 특징을 살려 실리식산을 다단계로 주입하여 입자 표면과 실리식산의 반응으로, 2~3 개의 입자가 결합한 형상의 콜로이달 실리카를 제조하였다. 이렇게 제조한 입자를 CMP 에 적용하여 콜로이달 실리카의 입자 형상에 따른 연마율을 기존의 상용 슬러리와 비교하였다. pH 가 높을수록 연마율은 높아졌고, 입자가 결합한 비구형의 콜로이달 실리카는 가장 높은 연마율과 양호한 비균일도를 나타내었다.

• 설비공학논문집
• /
• 제10권4호
• /
• pp.475-482
• /
• 1998

In this paper, an experimental study was conducted to investigate the performance of the spherical ice particle production system which uses the technology of water spray in a vacuum chamber for increasing the heat transfer area. As a result, following conclusions were obtained. The diffusion-controlled evaporation model agreed relatively well with experiments. The spray flow rate influences the performance of the system rather than any other factors, for example, the spray nozzle position, the nozzle number. As the spray rate increases, the system efficiency increases. It is due to the entrainment of small droplets among the spray with the exhausted vapor. Thus the system should be designed and operated to prevent the entrainment. Assuming the compressor efficiency to be 70%, the COP of the system reaches highly up to 6 at a maximum spray rate. Under the conditions, however, the rigid ice layer is obtained because ice particles bond together with increase of the spray rate. Therefore, the spray rate should be controlled properly to make the spherical ice particles.

• Archives of Pharmacal Research
• /
• 제7권2호
• /
• pp.145-151
• /
• 1984

A novel agglomeration technique, termed "Spherical Crystallization Process", which can transform directly the fine crystals produced in the crystallization or the reaction process into a spherical shape was developed. By this technique, needle like crystals such as salicylic acid were transformed into free flowing and directly compressible agglomerates. Sphericaly agglomerated aminophyline crystals were obtained directly from the reaction system, which could reduce the preparation processes, e. g. synthesis, crystallization and agglomeration, into only one step. Sodium theophyline monohydrate agglomerates were prepared by salting out, the rate process of which was described by a first order kinetics. Agglomerated crystals of ndw complex of indo-methacin-mepirizole were prepare with this technique; an improved therapeutic effect of the resultant crystals was expected. expected.

• Structural Engineering and Mechanics
• /
• 제15권4호
• /
• pp.463-476
• /
• 2003

This paper deals with nonlinear asymmetric dynamic buckling of clamped laminated angle-ply composite spherical shells under suddenly applied pressure loads. The formulation is based on first-order shear deformation theory and Lagrange's equation of motion. The nonlinearity due to finite deformation of the shell considering von Karman's assumptions is included in the formulation. The buckling loads are obtained through dynamic response history using Newmark's numerical integration scheme coupled with a Newton-Raphson iteration technique. An axisymmetric curved shell element is used to investigate the dynamic characteristics of the spherical caps. The pressure value beyond which the maximum average displacement response shows significant growth rate in the time history of the shell structure is considered as critical dynamic load. Detailed numerical results are presented to highlight the influence of ply-angle, shell geometric parameter and asymmetric mode on the critical load of spherical caps.

• 한국재료학회지
• /
• 제15권8호
• /
• pp.496-502
• /
• 2005

Green-light emitting $BaMgAl_{10}O_{19}:Mn^{2+}$ (BAM:Mn) phosphor particles were prepared by spray Pyrolysis. The effect of reactor temperature and flow rate of carrier gas in the spray Pyrolysis on the morphology, crystallinity and photoluminescence characteristics under vacuum ultraviolet were investigated. The morphology of the as-Prepared Particles obtained by spray Pyrolysis had spherical shape and non-aggregation characteristics regardless of the reactor temperature. The spherical shape of the as-prepared Particles obtained by spray pyrolysis at low temperature disappeared after Post-treatment. On the other hand the as-Prepared Particles obtained by spray Pyrolysis at $1600^{\circ}C$ maintained spherical shape and non-aggregation characteristics after post-treatment at $1400^{\circ}C$ for 3 h under reducing atmosphere. The BAM:Mn Phosphor Particles Prepared by spray Pyrolysis at different reactor temperatures had pure crystal structure and high photoluminescence intensities under vacuum ultraviolet after post-treatment. BAM:Mn phosphor particles prepared by spray Pyrolysis at low How rate of carrier gas had complete spherical shape and filed morphology and high photoluminescence intensity after post-treatment under reducing atmosphere.

• 대한기계학회논문집
• /
• 제19권10호
• /
• pp.2647-2656
• /
• 1995

The present work was performed to axially and radially investigate the local cold storage performance in the cylindrical tank with the spherical capsules inserted n-Tetradecane as a new cold storage material. The local cold storage performance of the capsules in the tank was experimentally investigated for the inlet temperature of -7, -5, -3, 0.deg. C, for the flow rate of 0.95, 1.89, 2.84, 6.00 l/min, and for the diameter ratio of 4.9, 9.0, 13.1. The local cold storage performance in the case of using water applied for the commercial ice-ball system was axially investigated by changing the flow rate only with the inlet temperature of -7.deg. C and the diameter ratio of 9.0 in order to compare with the performance in the case of using n-Tetradecane. For the case of using n-Tetradecane, the difference of cold storage period between the first and the seventh story was increased as the inlet temperature was increased and the flow rate was decreased. The capsules at the center of the tank showed the supercooling and the increased cold storage period compared with the capsules at the wall of the tank due to the small porosity and insufficient cold storage performance at the center of the tank as the diameter ratio is increased. The case using water showed worse cold storage performance due to comparatively large supercooling than the case using n-Tetradecane.

• Korea-Australia Rheology Journal
• /
• 제15권1호
• /
• pp.19-25
• /
• 2003

Since the microstructure of functional thin films depends on the dispersion characteristics of dense slurry, it is important to control the agglomerative nature of slurries under processing. The present authors have been discussing the model prediction of agglomerative nature and local rate of agglomeration in dense suspensions. The experiments have been peformed under shear flow using the nearly spherical and oblate type graphite particles. In this study, the experiment has been conducted using water and glycerol as dispersion media. Stress control type rheometer was used to measure the slurry rheology. Local agglomeration of graphite particles has been predicted by using Usui's model. The experimental results show that both the shape and slurry processing method affect on the local dispersion condition. The agglomeration formed by oblate type graphite particles seems to be more difficult to break up than that of spherical particles.

• Journal of Information Display
• /
• 제2권4호
• /
• pp.57-62
• /
• 2001

Green-emitting $Zn_2SiO_4$:Mn phosphor particles having a spherical shape and high luminescence intensities under VUV were prepared by spray pyrolysis process under severe preparation conditions. The type of precursor solutions affected the morphology and luminescence characteristics of the prepared particles. The particles prepared from the clear solution by laboratory-scale process had spherical shape and dense morphology, while the particles prepared from the severe preparation conditions had rough surface and collapsed structure. However, the particles prepared from the colloidal solution utilizing fumed silica were spherical in shape and filled morphology at the severe preparation conditions of high flow rate of carrier gas, high concentration of solution, and large reactor size. The prepared $Zn_2SiO_4$:Mn phosphor particles with complete spherical shape had higher photoluminescence intensity than that of the commercial product prepared by solid state reaction.