• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.45 no.5
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• pp.44-48
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• 2013

Ultrasonic treatment of KOCC was tried to explore the possibility for improvement of KOCC quality as a raw material for making industrial packaging paper and paperboard. The effect of pH, stock consistencies and treatment times on the ultrasonic response of KOCC were investigated. WRV, apparent density, tensile index and burst index were improved as pH of KOCC slurry is increased. However highest tear index and stiffness were obtained at pH 8. It was also found that the highest WRV and strength properties could be obtained at 0.5% of KOCC consistency during ultrasonic treatment. WRV and most strength properties were improved with ultrasonic treatment time. It was found that ultrasonic treatment can be used as a useful mean for KOCC modificaton.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.48 no.2
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• pp.28-33
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• 2016

This study was conducted to investigate the effects of deep eutectic solvent (DES) treatment on properties of TMP fibers and handsheets. DES was prepared by mixing of lactic acid and betaine (L and B), and the molar ratio of these two components mixtures was controlled to 2:1 (L:B=2:1) and 5:1 (L:B=5:1). As results, lignin was partly extracted from the TMP fibers. Especially, the delignification of TMP samples was promoted according to the increase of the molar ratio of lactic acid. Except for tear index, both tensile index and burst index of handsheets were increased when higher molar ratio of lactic acid was mixed for DES preparation. However, the LB DES treatment of TMP fibers didn't give any effect on the optical properties of TMP handsheets. The plausibility of TMP fiber was to be enhanced by LB DES treatment.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.29 no.3
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• pp.43-50
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• 1997

The purpose of this study was to decrease pollutants of effluents from KP bleaching. Multistage bleaching that combined with O, Eo, and C/D stage was conducted, after optimum bleaching conditions of O, Eo, and C/D stage were determined. Moreover the properties for bleached pulps and pollution level of bleaching effluent were measured by each standard method. Due to increase on the brightness and delignification of pulps by O, Eo, and C/D stage bleaching. It was possible that bleaching sequences were reduced from five stage to four stage. In addition to, OC/DEoD and OC/DEopD bleaching sequences had higher brightness than CEDED bleaching sequence. The pulps bleached by O and Eo stage had higher in tensile index than conventional bleaching sequences with the similar results in burst and tear index. While each bleaching sequences had little differences, bleaching sequences with Eo stage had higher in physical properties than with Eop stage. The pollution level measured by Chemical Oxygen Demand(COD), Biochemical Oxygen Demand(BOD) and Color of bleaching effluents were much lower in combined bleaching sequences of O, Eo and C/D stage than that of CEDED sequence. Particularly, a pollution index of bleaching effluents generated by C/DEoDEB and OC/DEopDED bleaching sequences were lower than that from the other bleaching sequences.

• Geomechanics and Engineering
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• v.14 no.5
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• pp.491-498
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• 2018

The Earth Mechanics Institute (EMI) was established at the Colorado School of Mines (CSM) in 1974 to develop innovations in rock mechanics research and education. During the last four decades, extensive rock mechanics research has been conducted at the EMI. Results from uniaxial compressive strength (UCS), Brazilian tensile strength (BTS), point load index (PLI), punch penetration (PP), and many other types of tests have been recorded in a database that has been unexamined for research purposes. The EMI database includes over 20,000 tests from over 1,000 different projects including mining and underground construction, and analysis of this database to identify relationships has been started with preliminary results reported here. Overall, statistically significant correlations are identified between bulk density and mechanical strength properties through UCS, BTS, PLI, and PP testing of sedimentary, igneous, and metamorphic rocks. In this paper, bulk density is considered as a surrogate metric that reflects both mineralogy and porosity. From this analysis, sedimentary rocks show the strongest correlation between the UCS and bulk density, whereas metamorphic rocks exhibit the strongest correlation between UCS and PP. Data trends in the EMI database also reveal a linear relationship between UCS and BTS tests. For the singular case of rock coral, the database permits correlations between bulk density of the core versus the deposition depth and porosity. The EMI database will continue under analysis, and will provide additional insightful and comprehensive understanding of the variation and predictability of rock mechanical strength properties and density. This knowledge will contribute significantly toward the increasingly safe and cost-effective geostructures and construction.

• Tunnel and Underground Space
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• v.25 no.1
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• pp.24-36
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• 2015

The Geochang granite widely used in construction works is one of the most popular dimension stones in Korea. In order to evaluate the physical properties of rock, a lot of laboratory tests for the Geochang granite were conducted to find unit weight, absorption ratio, P wave velocity, S wave velocity, uniaxial compressive strength, Young's modulus, Poisson's ratio, tensile strength, cohesion, friction angle and point load strength index. The uniaxial compressive strength of the Geochang granite was 19.5 times tensile strength and also 8.6 times cohesion, besides P wave velocity was 1.5 times S wave velocity. Correlation analyses were also conducted to find the correlation among 11 different physical properties, where the uniaxial compressive strength showed Pearson correlation coefficient of more than 0.8 with Poisson's ratio, point load strength index and Young's modulus, respectively. Regression analyses were finally conducted by means of both linear and multiple analysis and the brief results including coefficient of determination of more than 0.7 were presented.

• Korean Journal of Optics and Photonics
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• v.11 no.3
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• pp.147-151
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• 2000

We deposited the ion assisted ${Ta_2}{O_5}$ films and conventional thermal evaporated ${Ta_2}{O_5}$ films by using electron beam gun, and measured the optical properties and mechanical properties of the fabricated films according to the evaporation conditions. In the case of the TazOs films by oxygen ion assisted deposition with the anode voltage of 120 V, and current density of $50~500\muA/cm^2$, the refractive index exhibited 2.15 which was higher than the conventionally deposited film index 1.94 and the tensile stress exhibited $5.0\times10^8 dyne/cm^2$ which was lower than $7.0\times10^8 dyne/cm^2$. This properties coincided with the optical and mechanical properties of the films deposited at the elevated substrate temperature of $230^{\circ}C$. In the case of the argon ion assisted films the tensile stress was decreased but the absorption existed at the short wavelength in the visible spectral region. And all the fabricated films were found to be amorphous by the X-ray diffraction analysis. lysis.

• Journal of Forest and Environmental Science
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• v.14 no.1
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• pp.89-100
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• 1998

The study was carried to investigate the change of internal stress and physical properties of paper by the mutiplying of paper structuring that is an useful means to maximize the performance and use of the fiber raw material. The effects of recycled fiber on the physical properties of multiplied paper also were studied. The beating increased the internal stress of single layered paper, while filler loading decreased the internal stress. Multiplying the structure of paper decreased the internal stress and the most of physical properties except for tear index. It was found that the properties of paper could be changed by the pulp type, beating and the combination of raw materials. The introduction of filler in the middle and/or outer layer could improved the internal stress, tensile index, tear index and burst index. The addition of recycled fiber increased the opacity and stiffness of paper in both single layered and multiplied paper. Multiplying the structure of paper improved the air permeability and stiffness, while decreased burst index.

• Structural Engineering and Mechanics
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• v.42 no.2
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• pp.153-174
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• 2012

Micromechanical facture models can be used to predict ductile fracture in steel structures. In order to calibrate the parameters in the micromechanical models for the largely used Q345 steel in China, uniaxial tensile tests, smooth notched tensile tests, cyclic notched bar tests, scanning electron microscope tests and finite element analyses were conducted in this paper. The test specimens were made from base metal, deposit metal and heat affected zone of Q345 steel to investigate crack initiation in welded steel connections. The calibrated parameters for the three different locations of Q345 steel were compared with that of the other seven varieties of structural steels. It indicates that the toughness index parameters in the stress modified critical strain (SMCS) model and the void growth model (VGM) are connected with ductility of the material but have no correlation with the yield strength, ultimate strength or the ratio of ultimate strength to yield strength. While the damage degraded parameters in the degraded significant plastic strain (DSPS) model and the cyclic void growth model (CVGM) and the characteristic length parameter are irrelevant with any properties of the material. The results of this paper can be applied to predict ductile fracture in welded steel connections.

• Journal of The Korean Society of Agricultural Engineers
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• v.54 no.6
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• pp.151-158
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• 2012

This study will not only prove experimental dynamic properties which are classified to slump, compressed strength, bending strength and toughness index blast-furnace cement concrete with polypropylene (PP) fiber that refer properties and volume of it, but also establish a basic data in order to use PP fiber reinforced blast-furnace cement concrete. The slump didn't changed by PP fiber volume $5kgf/m^3$ because of flexibility of fiber in despite of loose mixing. The reason why the slump decreased steadily by PP fiber volume $3kgf/m^3$ was rising contact surface of water. The compressed strength indicated a range of 19.49~26.32 MPa. The tensile strength indicated a range of 2.10~2.44 MPa. The bending strength was stronger about 3~16 % in case of mixing with PP fiber volume than normal concrete. The flexure strength indicated a range of 4.30~4.83 MPa. The toughness indicated a range of $0{\sim}19.88N{\cdot}mm$ and was stronger about 6.7 times in case of PP fiber volume $9kg/m^3$ than PP fiber volume $1kg/m^3$. The pavement with PP fiber volume over such a fixed quantity in the roads of a respectable amount load can have a effect to prevent not only resistance against clack but also rip off failures.

• Transactions of Materials Processing
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• v.27 no.4
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• pp.211-221
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• 2018

To estimate the recycling feasibility of high melt-indexed polycarbonate, 3.5 inch LGP, tensile, flexural and impact specimens were injection-molded and the LGP was shredded into scraps. The scraps were injection-molded again and this process was repeated for 4 times. Properties of the sample, i.e., optical properties, mechanical properties and number average molecular weight were measured at each cycle. Based on the results, as the number of reprocessing increased, transmittance decreased at low wavelength and color coordinate was changed systematically to yellow. Yellow index increased more than twofold during 4 recycling processes. On the other hand, the number average molecular weight decreased during recycling processes. Flexural and impact strength showed no tendency according to the number of recycling, but tensile strength decreased sharply after the third recycling process. Based on these properties, it was concluded that the number of recycling for high melt-indexed polycarbonate allowed in this study was one.