• Journal of the Korean Society of Industry Convergence
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• v.23 no.1
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• pp.83-91
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• 2020

The evaluation of the compression behavior of the cushioning material is of importance to achieve appropriate packaging design. In order to change packaging design from polymeric-based to more eco-friendly cellulose-based nire effectively, comparative study on the compression behavior between these two packaging materials is crucial. In this study, the stress-strain behavior, hysteresis loss, and response characteristics for cyclic loading were analyzed through compression tests on multi-layered corrugated structure (MLCS) and expanded polystyrene (EPS) packaging materials. MLCS produced in Korea is produced by winding a certain number of single-faced corrugated paperboard, and the compression behavior of this material was turned out to be 6 stages: elastic stage, first buckling stage, sub-buckling stage, densification stage, last buckling stage and high densification stage. On the other hand, EPS's compression behavior was in 3 stages: linear elastic stage, collapse plateau, and densification stage. The strain energy per unit volume (strain energy density) of MLCS did not differ depending on the material thickness, but it showed a clear difference depending on the raw material and flute type. Hysteresis loss of MLCS ranged from 0.90 to 0.93, and there were no significant differences in the raw material and flute type. These values were about 5 to 20% greater than the hysteresis of the EPS (about 0.78 to 0.87).

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.05a
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• pp.118-121
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• 2007

Bulk metallic glass (BMG)/crystalline composites comprising a copper based BMG alloy and crystalline nickel were produced by means of eloctroless plating of nickel on $Cu_{54}Zr_{22}Ti_{18}Ni_6$ BMG powder and subsequent consolidation using spark plasma sintering. The plastic deformation behavior of BMG/crystalline composites was examined by uniaxial compression test at various temperatures in the supercooled liquid region (SLR) of the BMG alloy. The evolution of strain states during uniaxial compression was tackled by microstructure observations. Deformation temperature played an important role in the deformation behavior of BMG/crystalline composites, which was attributed to a strong temperature dependence of the flow stress of the BMG alloy in the SLR. BMG/crystalline composites deformed homogenously in the temperature range where the flow stress of the BMG alloy was close to that of crystalline nickel. In contrast, inhomogeneous deformation was observed in the temperature range where the flow stress of the BMG alloy largely differs from that of crystalline nickel.

• Advances in concrete construction
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• v.9 no.3
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• pp.249-256
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• 2020

This paper aims at investigating the effect of crumb rubber size and content on compressive behaviors of concrete under axial compression. Concrete specimens are designed and produced by replacing natural aggregate with crumb rubber content of 0%, 5%, 10%, 15% and three different sized crumb rubbers (No. 20, No. 40, No. 80 crumb rubber). And the failure mode, compressive strength, elastic modulus, stress-strain curves, peak strain and ultimate strain are experimentally studied. Based on the test results, formulas have been presented to determine the compressive strength, elastic modulus, the relationship between prism compressive strength and cube compressive strength, stress-strain curves and peak strain of crumb rubber concrete (CRC). It is found that the proposed formulas agree well with the test result on the whole, which may be used to practical applications.

• Journal of the Korean Society for Heat Treatment
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• v.33 no.4
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• pp.180-184
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• 2020

The crystallographic texture plays an important role in both the plastic deformation and the macroscopic anisotropy of magnesium alloys. In previous study for AZ80 magnesium alloy, it was found that the main texture components of the textures vary with the deformation conditions at high temperatures. Also, the basal texture was formed at stress of more than 15-20 MPa and the non-basal texture was formed at stress of less than 15-20 MPa. Therefore, in this study, uniaxial compression deformation of AZ80 magnesium alloy was carried out at high temperature (stress of 15-20 MPa). The uniaxial compression deformation is performed at temperature of 723 K and strain rate 3.0 × 10^-3s^-1, with a strain range of between -0.4 and -1.3. Texture measurement was carried out on the compression planes by the Schulz reflection method using nickel filtered Cu Kα radiation. EBSD measurement was also conducted in order to observe spatial distribution of orientation. As a result of high temperature deformation, the main component of texture and its development vary depending on deformation condition of this study.

• Journal of Korean Society of Steel Construction
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• v.16 no.4 s.71
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• pp.433-442
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• 2004

This paper discusses the development of a computer program to analyze elastic local buckling stress based on Eurocode 3 Part 1.3 for the flange and web of cold-formed channel columns under compression at elevated temperatures. The high-temperature, stress-strain relationships of the steel used in this paper were determined according to Eurocode 3 Part 1.2. The critical temperatures and the elastic local buckling stresses of cold-formed channel columns under compression at elevated temperatures were analyzed with the computer program developed in this study. Analysis examples were given to show the applicability of the computer program.

• Korean Journal of Agricultural Science
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• v.38 no.3
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• pp.533-540
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• 2011

This study is to develop a mulit-layer glued columns for construction of Korean-style houses by using domestic small diameter logs. Dried small square lumber glued each other to develop a multi-layer glued columns and evaluated its performance of strength. Then, predicted the design load of multi-layer glued columns and make a comparison between actual load and design load of multi-layer glued columns. In the results, allowable load by allowable stress of multi-layer glued columns was measured one-third of actual columns load and prediction load was measured less than 10~30% of the actual load. Therefore, muilt-layer glued member has a standard allowable stress of compressive of 13 MPa (Larix leptolepis) and 19 MPa (Chamaecyparis obtusa) when used as columns. Also, using compression strength of small diameter square logs could calculate maximum loads of multi-layer glued member as column.

• Transactions of Materials Processing
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• v.21 no.4
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• pp.228-233
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• 2012

In this study, powder compaction of AZO (alumina doped zinc oxide) powder was performed with a MTS 810 test system using a cylindrical die having a diameter of 10mm. Pressure-density curves were measured based on the load cell and displacement of the punch. The AZO powder compacts with various densities were formed to investigate the mechanical properties such as fracture stress of the AZO powder as a function of the compact density. Two types of compression tests were conducted in order to estimate the fracture stress using different loading paths: a diameteral compression test and a uniaxial compression test. The pressure-density curves of the AZO powder were obtained and the fracture stress of the compacted powders with various densities was estimated. The results show that the compact pressure dramatically increases as the density increases. Based on the experimental results, calibration of the modified Drucker-Prager/Cap model of the AZO powder for use in FE simulations was developed.

• Korean Journal of Metals and Materials
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• v.50 no.2
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• pp.100-106
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• 2012

This study was performed to fabricate porous titanium foam by three-dimensional layer manufacturing process, and to evaluate the porosities, compressive stress, Young's modulus and fracture pattern. Porous titanium foam was made of CP(Commercial Pure) titanium powder (${\leq}5{\mu}m$). Total porosities of titanium foam were in the range of 55-68%. Pore size distribution was $200-440{\mu}m$ for coarse pores, $50-100{\mu}m$ for intermediate pores and $5-10{\mu}m$ for fine pores. Compression elastic modulus and compression stress were decreased with increasing porosity. Young's modulus ranged from 1.04-5.62 GPa and maximum stress ranged from 20-241 MPa. Regarding the mechanical properties, 3D(Three Demensional) porous titanium fabricated layer manufacturing is a promising material for human bone replacement.

• Journal of The Korean Society of Agricultural Engineers
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• v.65 no.6
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• pp.51-63
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• 2023

To improve the problem that the settlement curve of the consolidation theory of Terzaghi does not match well with the actual settlement curve, we included a secondary compression settlement and analyzed it by varying the beginning point and then obtained the following results. The current methods of calculating the compression index from the  log𝜎 curve and the coefficient of consolidation from the time-dependent settlement curve for each consolidation pressure proved that the final settlement amount will be consistent after a long time, but the actual settlement amount will always be smaller than the predicted settlement amount during the settlement progress stage. The consolidation factors estimated by the curve fitting with the condition that the secondary compression begins in the second half of the primary compression showed similar values to the consolidation factors estimated by the curve fitting for the primary compression only, and the settlement curves were in better agreement throughout the compression. It showed different values, showing low validity. It can be inferred that secondary compression acts from the point when a significant portion of the excess pore water pressure is dissipated, and the loading stress begins to have more influence on the skeletal structure of the soil. Analysis results show that secondary compression begins at the range of 91 % to 98 % on the average degree of primary consolidation.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1994.03a
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• pp.139-148
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• 1994

An experimental study on material characterization and mechanical properties of SMC(Sheet Molding Compounds) compression molding parts was carried out. Simple compression test using grease oil as a lubricant was carried out to characterize flow stress of SMC at elevated temperatures. Two different mold temperatures, 130$^{\circ}C$ and 150$^{\circ}C$ and two different mold speeds, 15, 45mm/min were used for preparing the specimen of SMC compression molding parts. Surface roughness, tensile, and 3-point bending tests were used to determine the effects of molding temperatures and speeds on mechanical properties of compression molded SMC parts.