• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1996.06c
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• pp.283-292
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• 1996

This study was performed to determine the physical properties of rice hull and straw which could be used for an optimum design and operation of the handling facilities for these rice crop by-products. The properties measured were kinetic friction coefficient , bulk density, and dynamic and static angle of repose. Rice hulls with moisture content of 13% and 21% were used throughout the test while rice straws of 10% and 16% moisture were chopped into 10mm length and used for the test. Friction coefficient was calculated from the horizontal traction forces measurement when a container holding the mass of rice hull and straw was pulled over mild steel. PVC, stainless steel, and galvanized steel surface by a universal testing machine. Bulk density was measured by an apparatus consisting of filling fundel and a receiving vessel. Dynamic angle of repose which is the angle at which the material will stand when piled was calculated from the photos of bulk samples after they were flowed by gravity and accumulated on a circular surface. Static angle of repose which is the angle between the horizontal and the sloping side of the material left in the container when discharging was also measured in the similar way. Results and conclusions from this study are summarized as follows . 1. Kinetic friction coefficient of both rice hull and straw were in the range of 0.26 -0.52 and increased with the moisture content. The magnitude of friction increased in the order of galvanized steel, stainless steel, PVC ,and mild steel. 2. Bulk densities of rice hull decreased while those of rice straw increased with moisture content increase . Average bulk densities of rice hull and straw were 96.8 and 74.7kg/㎥, respectively. 3. Average dynamic angle of repose for rice straw was 32.6$^{\circ}$ and those for 13% and 21% moisture rice hull were 38.9$^{\circ}$ and 44.9$^{\circ}$ , respectively. 4. Static angles of repose for both rice hull and straw showed increase with the moisture content. The values were 75.2\ulcorner and 80.2$^{\circ}$ for 13% and 21% moisture rice hull, respectively. Rice straws having 10% and 16% moisture content showed 87.3% and 89.2$^{\circ}$ static angle of repose, respectively.

• Progress in Superconductivity
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• v.11 no.1
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• pp.42-46
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• 2009

With an aim of comparison, single grain Y-Ba-Cu-O (YBCO) bulk superconductors were fabricated using a liquid infiltration growth (LIG) process and a conventional melt growth (MTG) process with top seeding. The MTG process uses an $YBa_2Cu_3O_{7-x}$(Y123) powder as a precursor, while the LIG process uses $Y_2BaCuO_5(Y211)/Ba_3Cu_5O_8(Y035)$ pre-forms. The growth of a single Y123 domain on the top seed was successful in the both processes. Different feature between the two processes is the interior microstructure regarding the critical current density ($J_c$). The LIG-processed YBCO sample showed a lower porosity, more uniform distribution of Y211 particles and the enhanced Y211 refinement compared to the conventional MTG process. The $J_c$ improvement in the LIG process is attributed to the dispersion of finer Y211 particles as well as lower porosity within the Y123 superconducting matrix.

• Journal of Powder Materials
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• v.13 no.5 s.58
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• pp.351-359
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• 2006

Ni based($Ni_{57}Zr_{20}Ti_{18}Si_2Sn_3$) bulk metallic glass(BMG) powders were produced by a gas atomization process, and ductile Cu powders were mixed using a spray drying process. The Ni-based amorphous powder and Cu mixed Ni composite powders were compacted by a spark plasma sintering (SPS) processes into cylindrical shape. The relative density varied with the used SPS mold materials such as graphite, hardened steel and WC-Co hard metal. The relative density increased from 87% to 98% when the sintering temperature increased up to $460^{\circ}C$ in the WC-Co hard metal mold.

• The Journal of the Acoustical Society of Korea
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• v.25 no.2E
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• pp.49-55
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• 2006

Compressional wave velocity (Vp), shear wave velocity (Vs), elastic and physical properties, and electrical resistivity for two core sediments obtained from Southeastern Yellow Sea Mud (SEYSM) were measured and computed. The sediments consist of homogeneous mud (mostly silt and clay) with shells and shell fragments. As a result, the mean grain size is uniform ($7.5-8.5{\Phi}$ throughout the core sediments. However, physical properties such as wet bulk density and porosity show slightly increasing and decreasing patterns with depth, compared to the mean grain size. The compressional (about 1475 m/s in average) and shear wave (about 60 m/s in average) velocities with depth accurately reflect the pattern of wet bulk density and porosity. Electrical resistivity is more closely correlated with compressional wave velocity than physical properties. The computed Vp/Vs and Poisson's ratios are relatively higher (more than 10) and lower (approximately 0.002) than Hamilton's (1979) data, respectively, suggesting the typical characteristics of soft and fully water-saturated marine sediments. Thus, the Vp/Vs ratio in soft and unconsolidated sediments is not likely sufficient to examine lithology and sediment properties. Relationships between the elastic constant and physical properties are correlated well. The elastic constants (Poisson's ratio, bulk modulus, shear modulus) given in this paper can be used to characterize soft marine sediments saturated with seawater.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.47 no.3
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• pp.18-23
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• 2015

In this study, the effects of cationic fatty acid bulky promotor on the properties of BCTMP (bleached chemithermomechnical pulp) handsheet including bulk and strength were elucidated. As results, it was observed that the bulk of BCTMP handsheet increased with the increases of the concentration of cationic fatty acid bulky agent, while mechanical properties such as tensile strength and burst strength decreased. The opacity of BCTMP handsheet also increased with the increases of the concentration of cationic fatty acid bulky agent, while brightness was almost not changed. The effectiveness of bulky agent with SwBCTMP (softwood) was higher than that with HwBCTMP (hardwood). Compared with previous research on the effect of bulky agent on BKP handsheet, the bulk increase of BCTMP handsheet was greater compared to that of BKP handsheet. However, the reduction of mechanical property in BCTMP handsheet was lower than that of BKP handsheet.

• Plant Resources
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• v.2 no.1
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• pp.42-48
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• 1999

This study was undertaken to examine the feasibility of black locust (Robinia pseudoacacia) as substrates for several edible mushrooms. For the cultivation of several edible and/or medicinal fungi on black locust, optimum bulk densities, synthetic or semisynthetic additives, natural additives and pretreatment methods were investigated. Fruit body yields of the fungi on various sawdust media composed of different wood species were also analyzed for testing the capability of black locust as a substrate for mushroom production. Mycelial growths decreased proportional when the bulk density increased. The most suitable carbon and nitrogen sources as additives to promote the mycelial growth were sucrose (2%, w/w) and ammonium phosphate (0.2%, w/w) respectively. When corn-powder and beer-waste as natural additives were added to sawdust of black locust showed the significant growth of mycelia. And the optimum mixing ratio was 10:2:1 (sawdust: corn-powder: beer-waste, w/w). Black locust after cold water treatment showed the outstanding mycelial growths. Any significant changes of pH, moisture content (%) and dry-weight losses (%) could not be found among culture substrates (sawdust of black locust, oak and poplar wood) examined before and after harvesting of fruit bodies. Yield of fruit bodies on black locust culture media were comparable with those culture media composed with oak and poplar wood. The present work indicated strongly the potentiality of black locust as raw materials for edible and medicinal mushrooms.

• Journal of the Korean Ceramic Society
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• v.47 no.6
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• pp.560-565
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• 2010

Nano laminated bulk $Ti_3SiC_2$ was synthesized by hot press process using TiCx/Si powder mixture at the temperature range of $1300^{\circ}C\sim1500^{\circ}C$. pure $Ti_3SiC_2$ was synthesized by a hot pressing above $1400^{\circ}C$, while unreacted TiCx were remained in bulk $Ti_3SiC_2$ which synthesized below $1400^{\circ}C$. The sintering density of bulk $Ti_3SiC_2$ were varied with the amount of TiCx. It was found that the mechanical properties and micro structures of bulk $Ti_3SiC_2$ were closely related to the amounts of TiCx which was controlled by the hot pressing temperature. The TiCx increase the flexural strength of bulk $Ti_3SiC_2$, while the fracture toughness and thermal shock resistance of bulk $Ti_3SiC_2$ were decreased with the content of TiCx. The plastic deformations of bulk $Ti_3SiC_2$ were appeared above $1000^{\circ}C$.

• Journal of the Korean Ceramic Society
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• v.37 no.5
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• pp.497-504
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• 2000

In this study, mullite-zirconia comosite was fabricated by adding ZrOCl2.8H2O using of boehmite gel coating to Hadong kaolin (pink A grade) in order to enhance strength of the mullite specimens. The influence of ZrOCl2.8H2O content and fireing temperature on the crystall phase, microstructure, bulk density, strength of the specimens was investigated. Mullite-zirconia composite was produced in the process of coating zirconia to mullite powder synthesized thereafter and mixing simultaneously of starting materials with boehmite-zirconia gel. Maximum strength with in this study was 251 sintered at 1$600^{\circ}C$ for 2h. Bulk density and strength of the composite with zirconia coated mullite was higher than simultaneous on mixture of starting materials.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.04b
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• pp.76-79
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• 2000

The $Ba(Zn_{1/3}Ta_{2/3})O_3$ ceramics were prepared by conventional mixed oxide method. The structural properties of the BZT ceramics with the sintering temperature were investigated by XRD, SEM. The BZT ceramics have a complex-perovskite structure. The BZT ceramics sintered at $1550^{\circ}C$ had a superstructure plane of BZT(100). Increasing the sintering temperature, the bulk density and ordering were increased. The bulk density of the BZT ceramics sintered at $1550^{\circ}C$ was $7.50[g/cm^3]$. Increasing the sintering temperature, the average grain size were increased and pore were decreased.

• Journal of the Korean Magnetics Society
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• v.4 no.2
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• pp.89-93
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• 1994

Effects of density, inner-stress, and grain size on B-H hysteresis loop properties of Mg-ferrite were investigated. As the sintered bulk density increase, coercive force($H_c$) decreasand squareness ratio increase. Coercive force was very dependent on inner-stress in sintered body, so coercive force increase from 1.95[Oe] to 4.35[Oe] when inner stress present in bulk, however, the squareness ratio was almost not changed Coercive force and squareness ratio were independent on grain size of sintered body which is between 6-11[$\mu\textrm{m}$]