• Journal of Powder Materials
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• v.27 no.3
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• pp.210-218
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• 2020

A T-800 (Co-Mo-Cr) coating material is fabricated using Co-Mo-Cr powder feedstock and laser cladding. The microstructure and melted Al erosion properties of the laser-cladded T-800 coating material are investigated. The Al erosion properties of the HVOF-sprayed MoB-CoCr and bulk T-800 material are also examined and compared with the laser-cladded T-800 coating material. Co and lave phases (Co₂MoCr and Co₃Mo₂Si) are detected in both the laser-cladded T-800 coating and the bulk T-800 materials. However, the sizes of the lave phases are measured as 7.9 ㎛ and 60.6 ㎛ for the laser-cladded and bulk T-800 materials, respectively. After the Al erosion tests, the erosion layer thicknesses of the three materials are measured as 91.50 ㎛ (HVOF MoB-CoCr coating), 204.83 ㎛ (laser cladded T-800), and 226.33 ㎛ (bulk T-800). In the HVOF MoB-CoCr coating material, coarse cracks and delamination of the coating layer are observed. On the other hand, no cracks or local delamination of the coating layer are detected in the laser T-800 material even after the Al erosion test. Based on the above results, the authors discuss the appropriate material and process that could replace conventional bulk T-800 materials used as molten Al pots.

• Korean Journal of Food Science and Technology
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• v.24 no.2
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• pp.137-141
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• 1992

To investigate some factors on oleoresin extraction from red pepper, the content of yield, capsanthin and capsaicin in oleoresin extracted under various factors such as solvent, variety of materials, extraction time and temperature, storage condition of dried red pepper and its parts, particle size of raw material powder and the ratios of red pepper powder to extraction solvent were investigated. Ethyl alcohol and ethylene dichloride were effective in extracting capsanthin and capsaicin from red pepper, respectively. Mixed-solvent bore fruitful in increasing of oleoresin yield, but was fruitless in extracting capsanthin and capsaicin in comparison with single-solvent. In three varieties such as Juktoma, Jinsol and Dabok, Jinsol was excellent in oleoresin extraction. Optimum extracting temperature and time was $20^{\circ}C$ and three to five hours, respectively. Oleoresin quality from long-term storage and/or coarse red pepper were low in point of yield, capsanthin and capsaicin. Capsanthin and capsaicin were distributed into pericarp and seed in abundance, respectively. Optimum mixing ratio of red pepper powder to extracting solvent was suitable for one to three(1 : 3) or one to four(1 : 4) in oleoresin extraction.

• Advances in concrete construction
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• v.8 no.1
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• pp.65-76
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• 2019

This paper investigates the effect of recycled glass powder (RGP) on flowing properties of self-compacting mortars (SCMs) containing different ratios of fillers and superplasticizer dosages. Fly ash (FA), nano-silica (NS), micro-silica (MS), metakaolin (MK) and rice husk ash (RHA) are used as fillers and their synergistic effect with RFP is studied. The effects of fillers and high-range water reducer (HRWR) on flowing ability of mortars are primarily determined by slump flow and V-funnel flow time tests. The results showed that for composites with a higher RGP content, the mortar flowing ability increased but tended to decrease when the composites containing 10% MK or 5% RHA. However, the flowing ability of samples incorporating 5% RGP and 10% SF or 25% FA showed an opposite result that their slump flow spread decreased and then increased with increasing RGP content. For specimens with 3% NS, the influence of RGP content on flowing properties was not significant. Except RHA and MS, the fillers studied in this paper could reduce the dosage of HRWR required for achieving the same followability. Also, the mixture parameters were determined and indicated that the flowability of mixtures was also affected by the content of sand and specific surface area of cement materials. It is believed that excess fine particles provided ball-bearing effect, which could facilitate the movement of coarse particles and alleviate the interlocking action among particles. Also, it can be concluded that using fillers in conjunction with RGP as cementitious materials can reduce the material costs of SCM significantly.

• Journal of the Korea Institute of Building Construction
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• v.14 no.1
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• pp.11-20
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• 2014

This research examined the effect of the quality of aggregate on concrete workability and compressive strength through an investigation into regional aggregate used in domestic ready mixed concrete plants. Through the research, it was found that aggregate for ready mixed concrete shows poor quality overall. The main factor of deterioration in the quality of the concrete is the particle size of fine aggregate and fine particle content in coarse aggregate. The quality of aggregate significantly influences concrete's workability, which is defined based on 0.08mm passage related with powder and absorption. In addition, poor aggregate quality leads to increased water content in concrete to secure workability, which is related with a decline in the compressive strength and durability of concrete.

• International Journal of Concrete Structures and Materials
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• v.4 no.1
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• pp.17-23
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• 2010

The feasibility of the use of scrap tire rubber in concrete was investigated. The tests conducted in two groups: replacing of coarse aggregates with crumb rubber and cement particles with rubber powder. To distinguish the properties of new concrete, the following mechanical and durability tests were designed: compressive, tensile and flexural strength, permeability and water absorption. Rubber addition could affect the concrete properties depend on the type and percentage of the rubber added. Although the rubber addition modifies the mechanical characteristics of concrete in a way, but higher rubber content could not be useful. Concrete durability showed more dependency to the type of rubber instead of percentage of rubber. Moreover, to optimize the mechanical and durability of rubberized concrete, the useful percentage of rubber has been recommended.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.620-623
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• 2004

Waste concrete powder(WCP) has been estimated with a great value-added material as by-product of waste concrete manufactured to fine and coarse aggregate for concrete, because it is able to utilized for cement clinker and concrete admixture. In the experimental results for this study, chemical composition of WCP was similar to that of cement, and specific gravity of WCPs were 2.46 and 2.48 due to internal micro-void of WCP. Final setting of paste with WCP was delayed, and flow value of mortar with WCP was tendency to reduced in comparison with that of paste and mortar with only ordinary portland cement as replacement ratio of WCP increased. Furthermore, sorptivity of mortar with WCP was increased as replacement ratio of WCP increased. Compressive strength of mortar with $15\%$ WCP was developed about 27MPa at 28days.

• Journal of the Korean Ceramic Society
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• v.31 no.7
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• pp.772-776
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• 1994

Using two kinds of ZrO2 powder stabilized by 8 mol% and 3 mol% of Y2O3 several microstructures were designed; two single composition specimens of 8 mol% Y2O3-ZrO3 and 3 mol% Y2O3-ZrO2 and five mixture specimens with multi-layered structure and particulate mixture structure at a mixing ratio of 1:1 by weight. Electrical conductivities were measured from 250 to 75$0^{\circ}C$ in air using an impedance analyser, and fracture toughness at room temperature using the indentation method. Making the mixture structures was more effective in enhancing fracture toughness than electrical conductivity. At low temperatures 3 mol% Y2O3-ZrO2 showed the highest values in both electrical conductivity and fracture toughness, while at high temperature the specimens of alternately stacked planar and coarse granulated structure were most favorable.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.05a
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• pp.195-196
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• 2018

The Research is underway to utilize heavyweight concrete for various applications. One of them is to use heavy concrete as a marine concrete such as a breakwater to resist wave. Marine concrete is often complex in shape and requires high fluidity. When the heavyweight concrete is high fluidity, there is a high risk of segregation due to the high density of the coarse aggregate. Therefore, we evaluate the fluidity of heavyweight concrete using heavy fine aggregate. As a result of the fluidity evaluation of the heavyweight concrete, the fluidity of the heavy fine aggregate was similar to that of ordinary concrete. Therefore, it is considered that the use of heavy fine aggregate in the development of high fluidity heavyweight concrete will be one of the methods.

• Journal of The Korean Society of Agricultural Engineers
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• v.56 no.5
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• pp.45-54
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• 2014

This study was performed to evaluate compressive strength, flexural strength, static modulus of elasticity, stress-strain ratio and durability of abrasion on EVA concrete reinforced steel fiber (SF) in order to use hydraulic structures, underground utilities, offshore structures and structures being applied soil contaminated area. It is used ordinary portland cement, crushed coarse aggregate, nature fine aggregate, EVA redispersible polymer powder, superplasticizer and deforming agent to find optimum mix design of EVA concrete reinforced steel fiber. EVA concrete reinforced SF was effected on the improvement of mechanical properties and durability of abrasion.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2002.05a
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• pp.224-233
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• 2002

A common YBCO powder has been made from a mixture of Y123 and Y211 that heated at different temperatures, respectively. The synthesis temperature of Y211 is lower than Y123. If Y211 has been heated as a synthesis temperature of Y123, a particle size of it may be very coarse. It exist as one of main defects for superconductor. But We simultaneously synthesize a YBCO(its composition is (Y123+0.4Y211)+$lwt%CeO_2$) using polymeric complex method. In the YBCO, the Y123 is synthesized lower temperature than other methodes, and its crystal structure is orthorombic. For measurement of these superconducting properties, we fabricated a YBCO single crystal. The manufactured YBCO single crystal is measured a magnetic distribution device using 0.5Tesla magnet and trapped magnet fields in it are 0.2Tesla.