• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.36 no.2
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• pp.17-23
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• 2004

The effects of refining consistency and plate gap on the specific energy consumption and physical properties of liner were investigated. Higher refining consistency and narrower plate gap brought about the reduction of specific energy consumption to decrease the freeness. Refining consistency and plate gap did not affect the bulk, Taber stiffness and compression index. The reduction of freeness and/or the increase of specific energy consumption caused the decrease of bulk and Taber stiffness, but increased the compression index. The effect of grammage on bulk was not observed, but Taber stiffness and compression index were increased with grammage. The bulk was decreased with the reduction of freeness rapidly at the above 400 mL CSF, and then levelled off. It is expected that the reduction of energy consumption could be obtained from the application of higher refining consistency and narrower plate gap during refining.

• Journal of Ginseng Research
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• v.17 no.3
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• pp.224-227
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• 1993

Weight (g/root) and bulk density (g/$cm^3$) of tap root in 15-root-grade of 4-year-old white ginseng were investigated by specific gravity and weight-volume method. Bulk density measured by specific gravity ranged from 0.8 to 1.2g/$cm^3$ with almost normal distribution in frequency (number 1 of roots). Bulk density measured by volume-weight method had significant correlation with root weight. The percentage of high bulk density root (above 1.0) showed significant positive correlation with mean root weight or mean bulk density of root weight, indicating that the growth conditions for large root provide the better compactnes of root tissue.

• Explosives and Blasting
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• v.24 no.1
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• pp.29-37
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• 2006

The demand of the bulk emulsion explosives is being increased more and more by using the mechanization loading system in a domestic tunnel sites. Thus, a rational design criteria that is suitable for rock and circumstance condition has been required. In this study, authors investigated a optimum specific charging weight and resonable charging weight based on domestic blasting construction cases, which were performed by using a mechanization bulk emulsion explosives loading system up to now. Authors also analyzed the blasting results and got the following formula $({\Upsilon}= 0.669 + (0.0154{\times}RMR),\;r=0.81)$ from the relationship between a optimum specific charging weight of bulk exp. and rock mass rating. A range of resonable charging weight with a drilling depth is calculated considering a rock conditions.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2002.05a
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• pp.66-69
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• 2002

In the ideal forming theory(1), which has been deviously developed as a direct method for optimizing forming process, material elements are required to deform following the minimum plastic work path (or the proportional true strain path). Besides the general theory(2,3), specific ideal forming theories have been developed for membrane sheet forming(4) as well as two-dimensional steady bulk forming(5-7). In this work, the ideal forming theory was successfully applied for non-steady bulk forming under the plane strain condition. Here, the shape change complying with the minimum plastic work path, was effectively described by developing a numerical code based on the characteristic method. Numerical results obtained for a specific industrial part also include the optimum pre-forming shape and its evolving shape change to the final shape as well as the boundary traction history.

• Korean Journal of Materials Research
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• v.31 no.2
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• pp.101-107
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• 2021

Pores produced by carbonization in bulk graphite process degrade the mechanical and electrical properties of bulk graphite. Therefore, the pores of bulk graphite must be reduced and an impregnation process needs to be performed for this reason. In this study, bulk graphite is impregnated by varying the viscosity of the impregnant. The pore volume and pore size distribution, according to the viscosity of the impregnant, are analyzed using a porosimeter. The total pore volume of bulk graphite is analyzed from the cumulative amount of mercury penetrated. The volume for a specific pore size is interpreted as the amount of mercury penetrating into that pore size. This decreases the cumulative amount of mercury penetrating into the recarbonized bulk graphite after impregnation because the viscosity of the impregnant is lower. The cumulative amount of mercury penetrating into bulk graphite before impregnation and after three times of impregnation with 5.1cP are 0.144 mL/g and 0.125 mL/gm, respectively. Therefore, it is confirmed that the impregnant filled the pores of the bulk graphite well. In this study, the impregnant with 5.1 cP, which is the lowest viscosity, shows the best effect for reducing the total pore volume. In addition, it is confirmed by Raman analysis that the impregnant is filled inside the pores. It is confirmed that phenolic resin, the impregnant, exists inside the pores through micro-Raman analysis from the inside of the pore to the outside.

• Tribology and Lubricants
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• v.30 no.5
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• pp.295-302
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• 2014

The tribological behavior of an Fe-based bulk amorphous alloy while sliding against a AISI 304 disc is investigated using a unidirectional pin-on-disc type tribometer in dry and distilled water environments. The rod-shaped bulk pins are fabricated by suction casting. The crystallinities of the bulk amorphous alloys before and after the friction tests are determined by X-ray diffraction. The friction coefficient and specific wear rate of the amorphous pin in the water environment are found to be twice and thrice as much as in the dry environment at a low applied pressure, respectively. However, at a higher pressure, the friction coefficient and specific wear rate are 0.4 and 1.02 mg/(Nm/s), respectively, in the water environment. A microstructure analysis shows that the worn surface of the alloy is characterized by delamination from the smooth friction surface, and thus delamination is the main wear mechanism during the friction test in dry sliding environment. In contrast, brittle fracture morphologies are apparent on the friction surface formed in distilled water environment. For the sample tested at a lower sliding speed, the XPS data from the oxide layer are similar to those of the pure element with weak suboxide peaks. For higher sliding speeds, all the main sharp peaks representing the core level binding energies are shifted to the oxide region.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.6
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• pp.193-200
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• 2007

Micro forming is a suited technology to manufacture very small metallic parts(several $mm{\sim}{\mu}m$). Al5083 superplastic alloy with very small grains has a great advantage in achieving micro deformation under low stress due to its relatively low strength at a specific high temperature range. Micro forming of $Zr_{62}Cu_{17}Ni_{13}Al_8$ bulk Metallic glass(BMG) as a candidate material for this developing process are feasible at a relatively low stress in the supercooled liquid state without any crystallization during hot deformation. In this study, the micro formability of Al5083 superplastic alloy and bulk metallic glass, $Zr_{62}Cu_{17}Ni_{13}Al_8$, was investigated with the specially designed micro vibration forming system using pyramid-shape, V-shape and U-shape micro die pattern. With these dies, micro vibration forming was conducted by varying the applied load, time. Micro formability was estimated by comparing the hight of formed shape using non-contact surface profiler system. The vibration load effect to metal flow in the micro die and improve the micro formability of Al5083 superplastic alloy and $Zr_{62}Cu_{17}Ni_{13}Al_8$ bulk Metallic glass(BMG).

• Magazine of the Korean Society of Agricultural Engineers
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• v.34 no.E
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• pp.1-11
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• 1992

Increasing national concern on nonpoint source pollution of surface and ground water Systems has led researchers and policy makers to develop certain agricultural Best Management Practices. As an initial step of broad study program above mentioned, this study reflected the effects of different tillage practice on bulk density and degree of saturation on two regional soils, namely Tama silt loam and Catlin silt loam. Results may help to clarify some of the conflicting findings on the impact of tillage systems on these parameters and it may also explain some of the reasons for specific role that different tillage systems play regarding nonpoint source pollution from agricultural fields.

• Korea Trade Review
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• v.43 no.3
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• pp.125-145
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• 2018

The Baltic Shipping Exchange is reporting the Baltic Dry Index (BDI) which represents the average charter rate for bulk carriers transporting major cargoes such as iron ore, coal, grain, and so on. And the current BDI index is reflected in the proportion of capesize 40%, panamax 30% and spramax 30%. Like mentioned above, the capesize plays a major role among the various sizes of bulk carriers and this study is to analyze the influence of the factors influencing on charter rate of capesize carriers which transport iron ore and coal as the major cargoes. For this purpose, this study verified causality between variables using Vector Error Correction Model (VECM) and tried to derive a long-run equilibrium model between the dependent variable and independent variables. Regression analysis showed that every six independent variable has a significant effect on the capesize charter rate, even at the 1% level of significance. Charter rate decreases by 0.08% when capesize total fleet increases by 1%, charter rate increases by 0.04% when bunker oil price increases by 1%, and charter rate decreases by 0.01% when Yen/Dollar rate increases by 1%. And charter rate increases by 0.02% when global GDP increases by one unit (1%). In addition, the increase in cargo volume of iron ore and coal which are major transportation items of capesize carriers has also been shown to increase charter rates. Charter rate increases by 0.11% in case of 1% increase in iron ore cargo volume, and 0.09% in case of 1% increase in coal cargo volume. Although there have been some studies to analyze the influence of factors affecting the charterage of bulk carriers in the past, there have been few studies on the analysis of specific size vessels. At present moment when ship size is getting bigger, this study carried out research on capesize vessels, which are biggest among bulk carriers, and whose utilization is continuously increasing. This study is also expected to contribute to the establishment of trade policies for specific cargoes such as iron ore and coal.

• Journal of the Korean Geotechnical Society
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• v.31 no.11
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• pp.33-40
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• 2015

Volcanic rocks in Jeju Island indicate the differences in geological and mechanical characteristics from region to region, and have vesicular structure caused by various environmental factors. In this study, triaxial compressive strength tests were conducted for intact rocks sampled in northeastern onshore and offshore, southeastern offshore and northwestern offshore of Jeju Island. The estimated cohesion and internal friction angle from the results of triaxial compression tests were compared and analyzed with absorption, a parameter representing the vesicular properties of basalts in Jeju Island. As a result, it was found that the relationship between cohesion and absorption could be classified clearly, considering two different linear relationships in bulk specific gravity and absorption. As the absorption increases, the cohesion decreases exponentially. In addition, the internal friction angle decreases almost linearly with increasing in the absorption, regardless of the relationships in bulk specific gravity and absorption.