• Journal of the Korean Ceramic Society
• /
• v.51 no.5
• /
• pp.380-385
• /
• 2014

Clay-based membranes with submicron pore size were successfully prepared by a simple pressing process using low-cost starting materials(e.g., kaolin (K), bentonite (B), talc (T), and sodium borate). The green bodies were sintered at $1000^{\circ}C$ for 2 h in air. The effect of clay-mineral composition on the flexural strength of clay-based membranes was investigated. The porosity of the clay-based membranes could be controlled within the range of 34 - 42% by adjusting the starting composition. The flexural strength of the low-cost membranes depended on both the porosity and the ${\alpha}$-quartz content. In turn, the porosity and ${\alpha}$-quartz content were affected by the (B+T) /(K+B+T) ratio. The plot of strength relative to this ratio, showed a maximum when the ratio was 0.4. The typical flexural strength of these clay-based membranes (with ratio 0.4) was 28 MPa at 34% porosity.

• Textile Coloration and Finishing
• /
• v.31 no.4
• /
• pp.354-362
• /
• 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.

• Steel and Composite Structures
• /
• v.44 no.5
• /
• pp.691-705
• /
• 2022

Shear failure in reinforced concrete (RC) structures is very hazardous. This failure is rarely predicted and may occur without any prior signs. Accurate shear strength prediction of the RC members is challenging, and traditional methods have difficulty solving it. This study develops a JAYA-GBRT model based on the JAYA algorithm and the gradient boosting regression tree (GBRT) to predict the shear strength of RC slender beams without stirrups. Firstly, 484 tests are carefully collected and divided into training and test sets. Then, the hyperparameters of the GBRT model are determined using the JAYA algorithm and 10-fold cross-validation. The performance of the JAYA-GBRT model is compared with five well-known empirical models. The comparative results show that the JAYA-GBRT model (R² = 0.982, RMSE = 9.466 kN, MAE = 6.299 kN, µ = 1.018, and Cov = 0.116) outperforms the other models. Moreover, the predictions of the JAYA-GBRT model are globally and locally explained using the Shapley Additive exPlanation (SHAP) method. The effective depth is determined as the most crucial parameter influencing the shear strength through the SHAP method. Finally, a Graphic User Interface (GUI) tool and a web application (WA) are developed to apply the JAYA-GBRT model for rapidly predicting the shear strength of RC slender beams without stirrups.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.39 no.9
• /
• pp.901-907
• /
• 2015

The Vickers hardness test is a common method used to characterize the hardness of ceramic materials. However, the hardness is not a deterministic value, but is a random variable. The objective of this paper is to investigate the statistical properties of the bending strength and a set of Vickers hardness values in single $ZrO_2$ and composite $ZrO_2/SiC$ with a SiC additive. In this work, we compare the characteristic value and variation with the results based on Weibull statistical analysis. The probability distributions of the bending strength and Vickers hardness agreed relatively well with the Weibull distribution. We evaluate the scale parameter and shape parameter in asreceived $ZrO_2$ and $ZrO_2/SiC$ composite ceramics, as well as in their heat treated ceramics.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.6 no.3
• /
• pp.110-117
• /
• 2011

This study investigated possibilities for a new reducing shrinkage method of soybean oil(SO) and waste oil(WO) to compare with shrinkage reducing agent(RS) and expansion additive(EA). There was no big difference to flow, air contents, and compressive strength of plain to use SO and WO. For the reducing shrinkage performance, SO and WO was more effective than RS and EA, because their fatty acid reacted with calcium hydroxide of concrete to turn soap. For the pore distribution by porosimter, $0.01{\sim}0.1{\mu}m$ pores of SO and WO were 0 ml/g, and $10{\sim}100{\mu}m$ also remarkably lower than any others. In these results, it inferred that they filled up capillary pore and mitigated autogenous shrinkage by their saponification of their fatty acid and calcium hydroxide.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2008.11a
• /
• pp.67-71
• /
• 2008

Blast Furnace slag a pigiron waste that is produced more than 800 thousand tons per year, and micronized double quenching blast furnace slag improves flexibility of concrete, and even shows improvement effect of long-term intensity. However, the concrete that used micronized double quenching blast furnace slag is restricted in its use because of many problems to assure early intensity. Even micronized blast furnace slag can assure its early intensity of concrete when maximizing, and is considered that can be applied in high strength of blast furnace slag as an alternation material for Silica-fume that depends on overall import. Hereby this paper is revised activity index and fluidity of mortar that used Nano Slag that is produced by rotten Nano crush equipment to propose its size, and possible utility of Nano Slag that was produced by blast furnace slag made in Korea as an alternation material, with the conclusion as following. 1. To measure micronized Nano slag, it is judged that it should be in progress with BET method that is based on micronized Silica-fume for concrete. 2. As a result, the test based on KS L ISO 679 is shown to satisfy the basic additive size of KS F 2563 and of KS F 2567, and to determine new combination of stipulations. 3. The strength development of Nano Slag was shown excellent in the daily initial installment of 1, 3, 7 days against the basic additive. This is judged that contains CaO controlling initial strength against Silica-fume, and contributes to higher fineness than the basic blast furnace slag 1 type.

• Resources Recycling
• /
• v.26 no.6
• /
• pp.50-57
• /
• 2017

In this study, characteristics of Mongolian fly ash and the possibility of its use as a cement additive through grinding process were examined. Mongolian fly ash was larger than domestic fly ash and less spherical. The CaO content of Mongolian fly ash was higher than domestic fly ash and the other components were similar. After vibratory milling, the mean particle size of fly ash decreased to $7.9{\mu}m$ and the blaine increased. When milled fly ash was mixed with cement, it showed the best compressive strength value at 60 min. These strength values were higher than OPC at all curing times.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.24 no.5
• /
• pp.143-149
• /
• 2020

The purpose of this study is to manufacture a variable density - hybrid lattice structure control by filling the pore of the metal addictive manufactured lattice structure with lightweight reactive acrylic compounds(RAC). To apply the variable density - hybrid lattice structure to the construction industry, the enhancing adhesion - reactive acrylic compounds(EA-RAC) which increased the adhesion strength was manufactured by adding ordinary portland cement to the RAC. Finally, the EA-RAC was filled into the lattice structure to test the specific density, water absorption, and adhesion strength of the variable density - hybrid lattice structure. The results were obtained with density controllable, water absorption less than 1.0%, and 1-day bonding strength of 1.78 MPa to 1.98 MPa.

• Geomechanics and Engineering
• /
• v.8 no.1
• /
• pp.67-79
• /
• 2015

This article presents the result of laboratory study conducted on expansive soil specimens treated with lignin, rice husk powder (RHP) and rice husk ash (RHA). The amount of lignin produced from paper industry and RHP were varied from 0 to 20% and RHA from 0 to 10% by weight. The treated specimens were subjected to unconfined compressive strength (UCS),swelling test and Atterberg limit tests. The effect of additives on UCS and atterberg limit test results were reported. It was observed that the additives and curing duration had a significant effect on the strength value of treated specimens. Generally (except the sample treated with 20% RHP for 3-day) with increasing additive and curing duration the UCS value increases. A RHP content of 15% was found to be the optimum with regard to 3-day cure UCS.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2000.10a
• /
• pp.134-137
• /
• 2000

A study on the development of material for a light weight partition wall using material of gypsum and waste paper is be considered to improve workability, setting time, properties of strength by use of $\beta$-Gypsum for controling setting time. According th the experiments, as quantity of gypsum in binder increase, workability and strength of specimens deteriorate. Appropriate quantity of $\beta$-Gypsum was 3~6% of binder and When it was used more than 10%, setting time was so fast. When additive quantity of waste paper has increased to 1%, flexural strength decreased to some 8~12% and density decreased abort 3% in comparison with otherwise specimen.