• Tunnel and Underground Space
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• v.5 no.2
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• pp.144-154
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• 1995

In this paper, we make a study on comparison and evaluation of the seoul granite properties, which are unit weight, uniaxial compressive strength, Brazilian tensile strength and, point load strength. The typical result are as follow- 1. From the measured value of point load strength anisotropy index, the seoul granite is considered to be homogeneous. 2. There is a linear relationship between uniaxial compressive strength and size corrected point load strength index. 3. Brazilian tensile strength and size corrected point load strength index are closely tied together.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.47 no.4
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• pp.136-143
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• 2015

It is well known that the use of PCC as a filler for printing paper making brought about the serious deterioration of strength properties of paper, although PCC could be helpful to reduce the energy consumption. The use of modified PCC with NCC was tried to solve and/or reduce the strength deterioration problem. NCC was prepared from SwBKP by the acid hydrolysis. There was no significant changes in chemical properties and crystalline structure. However the cyrstallinity of NCC was higher than those of SwBKP. The different dosage of NCC was applied to modify the properties of PCC. 0.1% of NCC dosage was enough to improve ash retention and paper properties. The use of modified PCC with NCC as a filler improved ash retention, bulk, opacity and formation without the serious deterioration of strength properties. Thus the use of modified PCC with NCC might be helpful for not only reduction of energy consumption but also increase of filler dosage without the significant sacrifice of strength properties by the optimization of retention system.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.48 no.1
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• pp.61-66
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• 2016

In order to improve the bonding efficiency of starch adhesives and water resistance of corrugated board, mixing ratio of additives dosage was changed and its effects were analyzed. When the additives dosage was increased, bonding strength, vertical compression strength, bursting strength and water resistance were increased, because of hydroxyl groups or acetyl groups in starch adhesives and cellulose fibers of corrugated board were cross-linked by additives. When 1.0% glyoxal dosage was added, flat crush strength and vertical compression strength were increased. With 1.5% glyoxal, bonding strength and bursting strength were increased. However, 2.0% glyoxal dosage was added, most of strength except bursting strength were decreased. Thus, when the appropriate amount of additives are added during corrugated board production process, increased bonding efficiency of starch adhesives and higher water resistance of corrugated board can be achieved.

• Proceedings of the Korea Concrete Institute Conference
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• 1994.10a
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• pp.356-361
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• 1994

From the previous experimental test results, it has shown that shear that shear strength in lightweight concrete beams was about 85% on that in normal concrete beams. It is speculated that shear connectors in composite beams of steel and lightweight concrete associated with the longitudinal shear strength decrease more in strength than those in normal concrete. So this paper, as a study on strength of shear connectors in composite beams of steel and lightweight concrete slabs, has a purpose to compare the strength formula resulted from the push-out test of thirteen solid slab and four deck Plate slab with the established ones, and then to suggest a proper strength formula of the shear connectors. The established strength formula of the shear connectors is prescribed for $P_ps = 0.50A_s . \sqrt{f_C . E_C}$by AISC coed, but from the experimental test results the strength values of the shear connectors in lightweignt concrete slabs shows about 70% on those of the shear connectors in normal concrete slabs by AISC code. Therefore, as a strength formula this paper suggests to multiply the established strength formula by reduction factor$(\varphi=0.7)$.

• Steel and Composite Structures
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• v.1 no.2
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• pp.171-185
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• 2001

The design of tall buildings has recently provided many challenges to structural engineers. One such challenge is to minimise the cross-sectional dimensions of columns to ensure greater floor space in a building is attainable. This has both an economic and aesthetics benefit in buildings, which require structural engineering solutions. The use of high strength steel in tall buildings has the ability to achieve these benefits as the material provides a higher strength to cross-section ratio. However as the strength of the steel is increased the buckling characteristics become more dominant with slenderness limits for both local and global buckling becoming more significant. To arrest the problems associated with buckling of high strength steel, concrete filling and encasement can be utilised as it has the affect of changing the buckling mode, which increases the strength and stiffness of the member. This paper describes an experimental program undertaken for both encased and concrete filled composite columns, which were designed to be stocky in nature and thus fail by strength alone. The columns were designed to consider the strength in axial compression and were fabricated from high strength steel plate. In addition to the encased and concrete filled columns, unencased columns and hollow columns were also fabricated and tested to act as calibration specimens. A model for the axial strength was suggested and this is shown to compare well with the test results. Finally aspects of further research are addressed in this paper which include considering the effects of slender columns which may fail by global instabilities.

• Horticultural Science & Technology
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• v.16 no.2
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• pp.229-232
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• 1998

This study was conducted to determine the properties of seedling plate papers currently used in commercial production, then to get basic information for manufacturing new seedling plate paper. Imported seedling plate paper had high wet tensile and burst strengths in its usage circumstances. Wet tensile strength was very high with 38.7% of dry tensile strength. Wet burst strength was also very high with 62.4% of dry burst strength. The seedling plate paper contained about 30% of synthetic fibers. It had 10 Gurley sec. in air permeability indicating effective movement of air. Seedling plate papers were' made in laboratory scale. For sufficient sizing degree, the addition of 0.5% AKD (alkylketene dimer) by weight was good enough. Additional amount of AKD more than 0.5% by weight caused strength loss even though improving sizing effect. The addition of wet strength reagent such as Finex-B 2% by weight resulted in good strength and air permeability.

• Structural Engineering and Mechanics
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• v.14 no.2
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• pp.209-221
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• 2002

In this paper a fracture criterion is proposed for cracked cylindrical samples of high-strength prestressing steels of different yield strength. The surface crack is assumed to be semi-elliptical, a geometry very adequate to model sharp defects produced by any subcritical mechanism of cracking: mechanical fatigue, stress-corrosion cracking, hydrogen embrittlement or corrosion fatigue. Two fracture criteria with different meanings are considered: a global (energetic) criterion based on the energy release rate G, and a local (stress) criterion based on the stress intensity factor $K_I$. The advantages and disadvantages of both criteria for engineering design are discussed in this paper on the basis of many experimental results of fracture tests on cracked wires of high-strength prestressing steels of different yield strength and with different degrees of strength anisotropy.

• Journal of the Ergonomics Society of Korea
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• v.16 no.1
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• pp.73-83
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• 1997

It is improtant to get accurate information about the grip strength for designing ergonomic grips and handles. It has been known that the excessive and repetitive use of grip force and unnatural posture of the wrist may cause cumulative trauma disorders (CTDs) such as carpal tunnel syndrome, tendrome, tendonitis, DeQuervan's disease, etc. In this paper we have measured the grip strength for sitting and standing posture for Korean adults ; 114 males and 105 females aged from the 20's to above the 50's. And this paper performed statistical analysis for deriving characteristics between grip strength and anthropometric data. The results are as follows ; (1) The maximum grip strength posture is exerted under standing posture with the elbow in full extension (180 .deg. ) for both males and females (2) There is significant difference among posture, sex and right and/or left handedness (3) Grip strength decreases with age for male, but it traces an inverted U curve for female (4) Grip strength has corre- lations with the age, weight, height, BSA, forearm length, hand length, thickness of wrist, circumference of wrist, and breadth of wrist for males.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.43 no.4
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• pp.1-10
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• 2011

Beating or refining is an energy intensive process in paper industry. In India, most of the paper industries blend long fibered softwood pulps with short fibered hardwood or agro based pulps to get the paper properties of competitive level. Refining characteristics of the blend of pulps is very crucial with respect to freeness and strength properties. This study has been carried out to understand the refining behavior of three hardwood pulps and a softwood pulp. The hardwood and softwood pulps are blended in different proportions in two different ways; a) blending after their separate refining, and b) blending before refining followed by mixed refining of the blended pulps. Freeness of pulp, strength, optical and surface properties of paper along with formation have been determined and compared for both the refining methods. The fiber classification of refined pulps was also carried out to analyze the effect of refining method on fiber morphology. The mixed refining of hardwood and softwood pulps marginally affects the fiber morphology in comparison to separate refining of pulps. The strength and other properties of paper prepared from mixed refining of pulps are either better or comparable than those of separately refined pulps.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.40 no.1
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• pp.15-22
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• 2008

For the improvement of letterpress printing paper quality, special fibers obtained from the sea were used by mixing with wood fibers. The sizes of the special fibers, which were from red algae in the sea, were 0.5-1 mm in length, and 3-7 ${\mu}m$ in width, respectively, and the fibers were supplied by Pegasus Research Inc. for the study. From the study, it was found that 10% addition of algae fibers greatly improved paper surface strength and internal bonding strength. The compressibility was estimated by utilizing 'Print-surf method' at high clamping pressure and with hard backing. Again, 10% addition of algae fibers greatly improved the compressibility of the paper. These results were expected that algae and wood fibers were distributed evenly through the sheet, and integrated one another to leave no empty space inside the paper.