• 한국식품과학회지
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• 제34권6호
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• pp.1023-1029
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• 2002

본 연구는 천연전분과 hydroxypropyl화 전분에 가소제를 0, 16, 33, 50, 66% 비율로 첨가하여 RVA점도를 측정하고 필름을 제조한 후 물성을 측정하여 두 물성 사이의 상관관계를 알아보고자 행하였다. 필름의 인장강도는 가소제의 함량이 높아질수록 감소하였고 신장율과 수증기투과도는 증가하였으며 glycerol이 sorbitol보다 큰 변화를 보이는 것으로 나타났다. Hydroxypropyl화 전분이 천연전분에 비해 강도는 떨어지나 신장율은 높아지는 것으로 나타났고 수증기투과도는 2배 큰 것으로 나타났다. 가소제를 혼합하여 필름의 물성을 측정한 결과 sorbitol은 유연성보다는 필름의 강도를 유지하는 역할을 그리고 glycerol은 필름의 신장율을 증가시키는 역할을 하는 것으로 나타났다. RVA물성과 필름 물성의 관계에서 가장 연관성이 높은 것은 peak viscosity, 인장강도, 수증기투과도인 것으로 판명되었고 peak viscosity와 인장강도, peak viscosity와 수증기투과도의 관계는 각각 직선적인 것으로 나타났다. 따라서 RVA 물성 중 peak viscosity를 활용하여 필름의 인장강도, 수증기투과도를 예측할 수 있다고 판단되었다.

• 한국인쇄학회지
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• 제18권1호
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• pp.95-102
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• 2000

This paper presents the second part of a study of deinking using wort. Physical properties of deinked pulps such as tensile strength, bursting strength and tearing resistance were investigated. In order to analyze the properties, the fiber length and coarseness of deinked pulp was also measured. Results of deinking experiments showed that the deinking efficiency of enzyme treatments was higher than that of chemical treatments in strength properties such as tensile strength, bursting strength and tearing resistance on the the whole. we think that the reason why is that the fiber length and coarseness of deinked pulp with wort are more increased and decreased than those of deinked pulp with chemicals individually.

• Design & Manufacturing
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• 제8권2호
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• pp.23-29
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• 2014

Salt bath heat treatment is usually used but recently vacuum heat treatment is increased for the heat treatment of hot work die steels. The differences in two heat treatment processes were compared by testing the mechanical properties of heat treated products. With two different features of processes, mechanical properties such as hardness, tensile strength and impact strength of products show very different results. In this study salt bath heat treated products showed higher tensile strength and impact strength than vacuum heat treated products but hardness was not much different. These lower mechanical properties of vacuum heat treated products are due to differences in heating and quenching process.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2021년도 봄 학술논문 발표대회
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• pp.133-134
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• 2021

In this study, the effects of aggregates on the properties of concrete as a study to determine the mechanical properties of high-temperature damaged concrete were examined. The samples to be reviewed are cement paste, mortar, and concrete, and the strength characteristics were reviewed after heating the compression strength and tensile strength properties. The increase in magnetic shrinkage at around 100℃ showed a significant drop in strength in mortar, which does not contain aggregates or has a small diameter, and after 300℃, concrete showed a sharp drop in strength due to the hydration and aggregation of cement.

• Advances in concrete construction
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• 제13권 2호
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• pp.123-132
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• 2022

This paper aims to adapt Multilinear regression (MLR) to predict the strength and toughness of SIFCON containing various pozzolanic materials. Slurry Infiltrated Fibrous Concrete (SIFCON) is one of the most common terms used in concrete manufacturing, known for its benefits such as high ductility, toughness and high ultimate strength. Assessment of compressive strength (CS.), flexural strength (F.S.), splitting tensile strength (STS), dynamic elasticity modulus (DME) and impact energy (I.E.) using the experimental approach is too costly. It is time-consuming, and a slight error can lead to a repeat of the test and, to solve this, alternative methods are used to predict the strength and toughness properties of SIFCON. In the present study, the experimentally investigated SIFCON data about various mix proportions are used to predict the strength and toughness properties using regression analysis-multilinear regression (MLR) models. The input parameters used in regression models are cement, fibre, fly ash, Metakaolin, fine aggregate, blast furnace slag, bottom ash, water-cement ratio, and the strength and toughness properties of SIFCON at 28 days is the output parameter. The models are developed and validated using data obtained from the experimental investigation. The investigations were done on 36 SIFCON mixes, and specimens were cast and tested after 28 days of curing. The MLR model yields correlation between predicted and actual values of the compressive strength (C.S.), flexural strength, splitting tensile strength, dynamic modulus of elasticity and impact energy. R-squared values for the relationship between observed and predicted compressive strength are 0.9548, flexural strength 0.9058, split tensile strength 0.9047, dynamic modulus of elasticity 0.8611 for impact energy 0.8366. This examination shows that the MLR model can predict the strength and toughness properties of SIFCON.

• 한국염색가공학회지
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• 제31권4호
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• pp.354-362
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• 2019

In order to apply thermoplastic composites using PETG resin to various industrial fields such as bicycle frames and industrial parts, it is necessary to verify the impact resistance, durability and mechanical properties of the manufactured composite materials. To improve the mechanical properties, durability and impact resistance of PETG resin, an amorphous resin, in this study, compound and injection molding process were carried out using various additives such as TiO2, carbon black, polyolefin elastomer, and PETG amorphous resin. The thermal and mechanical properties of the thermoplastic composites, and the Charpy impact strength. The analysis was performed to evaluate the characteristics according to the types of additives. DSC and DMA analyzes were performed for thermal properties, and tensile strength, flexural strength, and tensile strength change rate were measured using a universal testing machine to evaluate mechanical properties. Charpy impact strength test was conducted to analyze the impact characteristics, and the fracture section was analyzed after the impact strength test. In the case of POE material-added thermoplastic composites, thermal and mechanical properties tend to decrease, but workability and impact resistance tend to be superior to those of PETG materials.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(II)
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• pp.5-8
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• 2005

This research is to present experimental materials model of high strength concrete for prediction of fire safety of structural members based on mechanical properties of materials during heating up to 800$^{circ}C$. The following conclusions are drawn from this study. First of all, between 100 to 200$^{circ}C$, the high strength concrete show degradation at 100$^{circ}C$ and restoration at 200$^{circ}C$. The high strength concrete show elastic deformation at 20 - 200$^{circ}C$. Second, between 300 to 400$^{circ}C$, the mechanical properties of the high strength concrete which are exposed to fire show $75\~95\%$ as compared to the original properties because the thermally expanded ingredients of concrete, aggregates and cement paste, etc. Finally, beyond 600$^{circ}C$, the high strength concrete shows $75\~80\%$ reduction in thermal properties as compared to the normal concrete in the range of 600 to 800$^{circ}C$ and it shows $10\~30\%$ as compared to the original properties.

• Advances in concrete construction
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• 제7권3호
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• pp.143-150
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• 2019

This study presents the fracture properties of nano modified medium strength concrete (MSC). The nano particle used in this study is nano silica which replaces cement about 1 and 2% by weight, and the micro steel fibers are added about 0.4% volume of concrete. In addition to fracture properties, mechanical properties, namely, compressive strength, split tensile strength, and flexural strength of nano modified MSC are studied. To ensure the durability of the MSC, durability studies such as rapid chloride penetration test, sorptivity test, and water absorption test have been carried out for the nano modified MSC. From the study, it is observed that significant performance improvement in nano modified MSC in terms of strength and durability which could be attributed due to the addition pozzolanic reaction and the filler effect of nano silica. The incorporation of nano silica increases the fracture energy about 30% for mix without nano silica. Also, size independent fracture energy is arrived using two popular methods, namely, RILEM work of fracture method with $P-{\delta}$ tail correction and boundary effect method. Both the methods resulted in nearly the same size-independent $G_F$ irrespective of the notch to depth ratio of the same specimen. This shows evidence that either of the two procedures could be used in practice for analysis of cracked concrete structures.

• Structural Engineering and Mechanics
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• 제62권3호
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• pp.357-364
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• 2017

This paper presents the results of a study that investigated the improvement of the mechanical properties of coarse and fine recycled asphalt pavement (RAP) produced by adding silica fume (SF) with contents of 5%, 10%, and 15% by total weight of the cement. The coarse and fine natural aggregate (NA) were replaced by RAP with replacement ratio of 20%, 40% and 60% by the total weight of NA. In addition, SF was added to NA concrete mixes as a control for comparison. Twenty eight mixes were produced and tested for compressive, splitting tensile and flexural strength at the age of 28 days. The results show that the mechanical properties decrease with as the content of RAP increases. And the decrease in the compressive strength was more in the fine RAP mixes compared to the coarse RAP mixes, while the decrease in the splitting tensile and flexural strength was almost the same in both mixes. Furthermore, using SF enhances the mechanical properties of RAP mixes where the optimum content of SF was found to be 10%, and the mechanical properties enhancement of coarse RAP were better than fine RAP mixes. Accordingly, the RAP has the potential to be used in the concrete pavements or in other low strength construction applications in order to reduce the negative impact of RAP on the environment and human health.

• 한국압력기기공학회 논문집
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• 제8권2호
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• pp.7-13
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• 2012

A spacer grid which is one of the most important structural components in a pressurized water reactor fuel is an interconnected array of slotted grid straps, welded at the intersections to form an egg-crate structure. The spacer grid is required to not only protect fuel rods stably but also have sufficient lateral crush strength for the sake of enabling shut-down of the nuclear reactor during abnormal operating environments. Then, the lateral crush strength of the spacer grid is closely related with welding quality of the spacer grid. Previous research on the crush strength analysis of the spacer grid had been performed using only parent material properties. In this study, to investigate the effect on the crush strength of the spacer grid when used mechanical properties in weld zone instead of parent material properties, crush strength analysis considering mechanical properties in weld zone obtained from the instrumented indentation technique was performed and compared the results with the previous research.