• Transactions of Materials Processing
• /
• v.21 no.5
• /
• pp.305-311
• /
• 2012

One of the main methods of building LNG tankers uses the Moss spherical tank design since it can be precisely analyzed with respect to reliability and safety of construction by stress analysis. Aluminum alloy 5083 is generally used in the Moss spherical tank design for the wall in constructing the LNG tanker. This aluminum alloy does not have low temperature brittleness, but has good corrosion resistance, good weldability, and excellent material properties for the application. The Moss spherical tank is constructed with several sections of A5083 thick plate with curved surfaces, which are welded together. It is essential to predict the amount of springback for the deformed thick plates in design to insure a reliable construction because the structure needs to be assembled into a perfect sphere. Unless the initial construction meets the design, there are additional processing costs for reworking to meet the specifications as well as a cost penalty paid to a consumer. In this paper, FE analyses were conducted to predict the amount of springback for various forming conditions and forming processes. The various forming processes were evaluated with respect to reducing springback and compared with the conventional forming process used for curved surfaces of thick Al plate.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.61 no.1
• /
• pp.50-56
• /
• 2012

The Multi D.O.F spherical motor can drive rotating as well as tilting three degree of freedom with one motor. Existing three degree of freedom to drive with three motors that are connected by gears and belts, that will be too large size and big loss at gears and belts. So Reducing system size and improving efficient is using the Multi D.O.F spherical motor in three degree of freedom systems. For this reason, efficiency of Multi D.O.F spherical motor is one of the important performance indiccators. In this paper presented that how to improve the efficiency of the Multi D.O.F spherical motor. The fist of method is using the stator iron core's material with high permeability and resistivity for reducing the eddy current loss. However, it was the disadvatages of motor-making and economic. So author propose the resonable method of reducing the eddy current loss in the stator iron core. That is using the rotor with double-air gap.

• Journal of the Korean Ceramic Society
• /
• v.30 no.7
• /
• pp.563-570
• /
• 1993

Spherical, monosized gadolinium compound was prepared by the reaction of Gd(NO3)3 solution with decomposition products of urea in the solution at evaluated temperature. Chemical composition and calcination characteristics of spherical gadolinium compound prepared were investigated by X-ray IR and TG-DTA. The approximate chemical composition of the spherical particle precipitated was Gd(OH)CO3.1.5H2O. Gd(OH)CO3.1.5H2O was calcined to monoclinic type Gd2O3 at 115$0^{\circ}C$ via cubic type Gd2O3 near $600^{\circ}C$. The effects of various parameters such as pH, temperature, concentration ratio of urea to gadolinium precusor, ageing time, and others material (CCl3COOH and HOCNH2) in stead of urea as precipitating agent on the properties of the resulting precipitates were studied systematically.

• Preventive Nutrition and Food Science
• /
• v.18 no.1
• /
• pp.60-66
• /
• 2013

The whole saltwort plant (Salicornia herbacea) was micronized to develop the table salt substitute. The micronized powder was mixed with distilled water and made into a spherical granule by using the fluid-bed coater (SGMPDW). The SGMPDW had superior flowability to powder; however, it had low dispersibility. To increase the dispersibility of SGMPDW, the micronized powder was mixed with the solution, which contained various soluble solid contents of saltwort aqueous extract (SAE), and made into a spherical granule (SGMPSAE). The SGMPSAE prepared with the higher percentages of solid content of SAE showed improved dispersibility in water and an increase in salty taste. The SGMPSAE prepared with 10% SAE was shown to possess the best physicochemical properties and its relative saltiness compared to NaCl (0.39). In conclusion, SGMPSAEs can be used as a table salt substitute and a functional food material with enhanced absorptivity and convenience.

• Journal of Powder Materials
• /
• v.22 no.4
• /
• pp.260-265
• /
• 2015

Spherical fine cobalt powders were fabricated by new liquid reduction method. Commercial cobalt sufate heptahydrate was used as raw material. Also ethylene glycol was used as solvent and hydrazine-sodium hypophosphite mixture was used as reduction agent for the new liquid reduction method. A plate shaped cobalt powders with an approximately 300 nm were prepared by a traditional wet ruduction method using distilled water as solvent and hydrazine. Spherical fine cobalt powders with an average size of $1-3{\mu}m$ were synthesized by a new liquid reduction method in 0.3M cobalt sulfate and 1.5M hydrazine-0.6M sodium hypophosphite mixture at 333K.

• YAKHAK HOEJI
• /
• v.18 no.4
• /
• 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.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2010.04a
• /
• pp.268-271
• /
• 2010

In this paper, forward and reverse analysis is introduced in order to estimate the elastic-plastic properties from a power-law hardening bulk specimen materials with one simple spherical indentation impression test. In order to verify the reliability of the reverse analysis, we have simulated about a large range of materials that essentially cover all engineering materials, using ABAQUS(6.91) program. Then, we could obtained the fitting functions and plastic parameters from the numerical analysis results. Next, through the procedure of reverse analysis we can obtain the yield stress and power-law exponent. Finally, obtain good agreement between the result from reverse analysis and initial input data from experiment.

• Transactions on Electrical and Electronic Materials
• /
• v.14 no.2
• /
• pp.101-104
• /
• 2013

The effect of the mixing ratio of spherical silica on the electrical insulation breakdown strength in an epoxy/silica composite was studied. Spherical silicas with two average particle sizes of $5{\mu}m$ and $20{\mu}m$ were mixed in different mixing ratios, and their total filling content was fixed at 60 wt%. In order to observe the dispersion of the silicas and the interfacial morphology between silica and epoxy matrix, scanning electron microscopy (SEM) was used. The electrical insulation breakdown strength was estimated in sphere-sphere electrodes with different insulation thicknesses of 1, 2, and 3 mm. Electrical insulation breakdown strength decreased with increasing mixing ratio of $5/20{\mu}m$ and the thickness dependence of the breakdown strength was also observed.

• Journal of the Korean Ceramic Society
• /
• v.51 no.4
• /
• pp.367-373
• /
• 2014

In this study, the reducing agent hydrazine and precipitator NaOH were used with $NiCl_2$ as a starting material in order to compound Ni-based material with spherical nano characteristics; resulting material was used as an anode for SOFC. Synthetic temperature, pH, and solvent amounts were experimentally optimized and the synthesis conditions were confirmed. Also, a 0 ~ 0.15 mole ratio of metal(Co, Fe) was alloyed in order to increase the catalyst activation performance of Ni and finally, spherical nano $Ni_{(1-x)}-M_{(x=0{\sim}0.15)}$(M = Co, Fe) alloy materials were compounded. In order to evaluate the catalyst activation for hydrocarbon fuel, fuel gas(10%/$CH_4$+10%/Air) was added and the responding gas was analyzed with GC(Gas Chromatography). Catalyst activation improvement was confirmed from the 3% hydrogen selectivity and 2.4% methane conversion rate in $Ni_{0.95}-Co_{0.05}$ alloy; those values were 4.4% and 19%, respectively, in $Ni_{0.95}-Fe_{0.05}$ alloy.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2011.10a
• /
• pp.31.1-31.1
• /
• 2011

$Li_4Ti_5O_{12}$ is emerging as a promising material with its good structure stability and little volume change during the electrochemical reaction. However, its electrochemical performance is significantly limited by low electronic or ionic conductivity. In addition, high tap density is needed forim proving its volumetric energy density and commercialization. To enhance these properties, the spherical-like $Li_4Ti_5O_{12}$ particles were synthesized and carried out doping with yttrium. Prepared Y-doped $Li_4Ti_5O_{12}$ as a anode material showed great capacity retention rate of 92% (5C/0.2C), compared with no dope done. Consequently, it was found that Y doping into $Li_4Ti_5O_{12}$ matrix reduces the polarization and resistance on SEI layer during the electrochemical reaction.