• 펄프종이기술
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• 제35권2호
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• pp.26-32
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• 2003

For the purpose of manufacturing water-resistant corrugated board boxes for agricultural products in the cold chain system, the effects of fiber types, wet strength agents and a moisture-proof chemical on the properties of the base papers were investigated first. PAE(polyamide amine epichlorohydrin) showed better performance than MF(melamine formalde-hyde) over broad stock pH ranges, which was prefered as wet strength agent for the paper grade. When short fibers(AOCC, KOCC) were mixed with long fiber(UKP) in certain ratios, some physical properties of the paper made with mixed fibers were similar to those of the paper made with UKP only. Paper containing AOCC showed the biggest increase in water resistance when PAE was added to the stock. Synergistic effects in moisture-proof and some mechanical properties of paper were appeared when PAR was added internally, together with the coating of a moisture proof chemical on the sheets.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2007년도 추계 학술논문 발표대회
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• pp.37-40
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• 2007

This study investigates the effect of the pre-mix cement to the physical properties of the concrete according to the various combinations of the binders and the silica fume types. The results are summarized as following. For the properties of the fresh, the fluidity in the case that OPC+cilica fume-blast-furnace slag is appropriate compared to OPC+cilica fume+fly ash. Expecially, it is favorable when pre-mix is used. The fluidity time of the A, B depending on silica fume types is favorable, but it is decreased on C. The air content depending on silica fume types is low when the fly ash is used. Specially, the air content in the case that pre-mix is used is low caused by the dispersion of the silica fume. For the properties of the hardened concrete, the compressive and flexible strength when the blast-furnace slag is pre-mixed are high, and they exceed OPC. The strength depending on the silica fume types is high on B, and the strength of the others is similar.

• 대한치과기공학회지
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• 제35권4호
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• pp.313-320
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• 2013

Purpose: The purpose of this study was to know the physical properties of UDMA dental composite resins containing two photosensitizers, PD, DA, as a photosensitizer instead of CQ. We want to know Remaining Double Bond(RDB) of UDMA unfilled resin and diametral tensile strength and flexural strength of composite resin containing PD and DA were compared with those of CQ, most widely used photosensitizer for dental composite resins. Methods: The RDB of UDMA studied by FT-IR spectroscopy increased with irradiation time. The composite resins were tested for their physical properties. The dental composite resins were made with UDMA as a monomer, silanized silica as filler, N,N-dimethylaminoethyl methacrylate (DAEM) as amine initiator, and one of the two kinds of new photosensitizers. Results: The relative RDB of UDMA was in the order: DA > CQ > PD but the physical properties of the composite resins show PD and DA with higher results compared with that containing CQ. The reason for the results is that PD and DA serve not only as a photosensitizer but also as a photo-crosslinking agent. Conclusion: PD and DA show as effective photosensizers, suitable for UDMA dental composite resin compare with a higher efficiency than CQ.

• 한국가구학회지
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• 제18권1호
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• pp.39-46
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• 2007

This study was carried out to investigate the wood properties for efficient utilization of warm temperate tree species of Quercus acuta Thunb. grown in Korea. Fundamental wood properties in the anatomical, physical, mechanical and chemical characteristics were examined. Quercus acuta Thunb. is a radial-porous, straight grained and fine textured wood. The heartwood is not clearly distinguished from the sapwood. In physical properties, it has a high oven-dry specific gravity of $0.85{\pm}0.02$, and high shrinkage from green to air-dried condition of $7.05{\pm}0.52%$ in radial and $11.13{\pm}0.48%$ in tangential direction. Mechanical properties determined are strong with the MOR of $1,065{\pm}90kgf/cm^2$, and tensile strength parallel to grain of $1,490{\pm}258kgf/cm^2$ and shear strength of $175{\pm}13kgf/cm^2$. Also, this wood has high extractive contents: 11.11% for cold and 13.51% for hot water.

• 한국안전학회지
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• 제19권2호
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• pp.104-111
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• 2004

The aim of this study was to investigate the influence of inorganic pigments on the physical properties of cement mortar. For this purpose, the compressive strength and absorption test were carried out on cement mortar imxed with inorganic pigments by changing the proportion of cement mortar, water-cement ratio, and ratio of pigment. The result of this study can be summarized as follows: the compressive strength of colored mortar rapidely increased in red and yellow mortar, as the mix ratio of pigment increased. In case of green and black mortar, however, the compressive strength decresed as the mix ratio incresed. In case of red and yellow mortar, the absorption of colored mortar increased as the mixing ratio increased, if the mean particle diameter of the pigment is small. In case of green and black mortar, the absorption ratio decreased as the mix ratio increased. After investigating the overall physical properties of colored mortar, it was confirmed that the proper mix ratio of pigment securing the properties of colored mortar was below 6% of the weight of the cement to be used.

• 한국재료학회지
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• 제31권6호
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• pp.339-344
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• 2021

Composite materials offer distinct and unique properties that are not naturally inherited in the individual materials that make them. One of the most attractive composites to manufacture is the aluminum alloy matrix composite, because it usually combines easiness of availability, light weight, strength, and other favorable properties. In the current work, Powder Metallurgy Method (PMM) is used to prepare Al2024 matrix composites reinforced with different mixing ratios of yttrium oxide (Y₂O₃) particles. The tests performed on the composites include physical, mechanical, and tribological, as well as microstructure analysis via optical microscope. The results show that the experimental density slightly decreases while the porosity increases when the reinforcement ratio increases within the selected range of 0 ~ 20 wt%. Besides this, the yield strength, tensile strength, and Vickers hardness increase up to a 10 wt% Y₂O₃ ratio, after which they decline. Moreover, the wear results show that the composite follows the same paradigm for strength and hardness. It is concluded that this composite is ideal for application when higher strength is required from aluminum composites, as well as lighter weight up to certain values of Y₂O₃ ratio.

• Journal of the Korean Wood Science and Technology
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• 제50권2호
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• pp.134-147
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• 2022

The objective of this study is to determine the effect of fiber direction arrangement and layer composition of hybrid bamboo laminate boards on the physical and mechanical properties. The raw material used was tali bamboo (Gigantochloa apus (J.A. & J.H. Schultes) Kurs) rope in the form of flat sheets (zephyr) and falcata veneer (Paraserianthes falcataria (L) Nielsen). Zephyr bamboo was arranged in three layers using water-based isocyanate polymer (WBPI) with a glue spread rate of 300 g/m². There were variations in the substitution of the core layer with falcata veneers (hybrid) as much as two layers and using a glue spread rate of 170 g/m². The laminated bamboo board was cold-pressed at a pressure of 22.2 kgf/cm² for 1 h, and the physical and mechanical properties were evaluated. The results showed that the arrangement of the fiber direction significantly affected the dimensional stability, modulus of rupture, modulus of elasticity, shear strength, and screw withdrawal strength. However, the composition of the layers had no significant effect on the physical and mechanical properties. The bonding quality of bamboo laminate boards with WBPI was considered to be quite good, as shown by the absence of delamination in all test samples. The bamboo hybrid laminate board can be an alternative based on the physical and mechanical properties that can meet laminated board standards.

• Journal of the Korean Wood Science and Technology
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• 제44권6호
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• pp.842-851
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• 2016

The objective of this study was to improve physical and mechanical properties of soft-inner part of oil palm trunk (S-OPT) after impregnation with phenol formaldehyde (PF) resin and densification by close system compression (CSC) method. Effect of different methods of PF resin impregnation (i.e., no vacuum-pressure, vacuum, and vacuum-pressure) was evaluated. The results showed that PF resin impregnation and CSC significantly improved the physical and mechanical properties of S-OPT up to: (1) 176% in density; (2) 309% in modulus of rupture (MOR); (3) 287% modulus of elasticity (MOE); and (4) 191% in the compressive strength. Physical and mechanical properties of S-OPT showed their best performances when PF resin impregnated with vacuum-pressure method as shown by higher weight gain, density, MOR, MOE, compressive strength, and lower recovery of set due to better penetration of PF resin into S-OPT. Combining PF resin impregnation and densification by CSC method could be a good method to improve physical and mechanical properties of S-OPT.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2003년도 학술발표논문집
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• pp.399-402
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• 2003

This study is performed to examine the physical and mechanical properties of the high strength concrete using recycled aggregate. The recycled aggregate is replaced by 0%, 25%, 50%, 75%, 100% of natural crushed aggregate. The compressive strength of the concrete used recycled aggregate is shown in more than $400kgf/cm^2$ at the curing age 28 days. But the pulse velocity and dynamic modulus of elasticity are decreased with increasing the content of recycled aggregate. Accordingly, these recycled aggregate concrete can be used for high strength concrete.

• 한국농공학회논문집
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• 제50권5호
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• pp.73-81
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• 2008

This study evaluated the applicability of in-situ concrete pile as a stabilization materials of embankment slopes including agricultural reservoir and rural road etc. The experimental embankment slopes was constructed to investigate the strength properties of in-situ concrete pile with embankment materials and boring methods. The test variable were applied the boring method(driving and augering) and water-cement ratio. In order to analyze the physical and mechanical properties of embankment materials, permeability and water contents test were was performed. Also, the freshly and harden of in-situ concrete properties were measured by the slump and compressive strength tests. The results showed the water content and permeability of embankment materials and boring methods affected on compressive strength of in-situ concrete pile.