• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.34 no.5
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• pp.333-336
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• 2021

Oxide YBCO bulk superconductors are manufactured using the melt process. Because seed crystal growth method utilizes a slow-spreading layer-by-layer reaction, a long-term heat treatment is required to manufacture a single-crystal specimen of several cm. In this study, the melt process method was applied to compensate for the shortcomings of the seed crystal growth method. The thickness of the upper and lower pellets of the YBCO bulk was molded to 40 mm, and YBCO superconductor was produced by heat treatment. The measurement results of capture magnetism was in line with the literature. This results in a relationship that the higher the growth of Y211 particle in the YBCO, the higher the superconducting properties. We analyzed the YBCO superconductor, focusing on the Y₂BaCuO₅ particle distribution.

• Applied Chemistry for Engineering
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• v.23 no.1
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• pp.77-85
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• 2012

Production process of the flexible ceramic foamed body through the complexation with the fiberous sepiolite and expanded pearlite was researched. The processing of fibrillation of the inorganic mineral fiber sepiolite is the most important whole processing for manufacturing of the ceramic foamed body consisting of the expanded perlite and sepiolite. The fibrous sepiolite and expanded pearlite are blended and becomes the slurry phase. And this slurry phase is converted to a massive foamed body through the low temperature heat treatment process less than $300^{\circ}C$. The heat-treatment process of the slurry phase composite has to be designed to include the evaporation step of the moisture remaining among the slurry composition, foaming step by the decomposition of the foaming agent, and resolution removal step of the organic material which was added in the composite remained after the foaming step. The heat treatment process should be considered as significant factors in design of total process. As to the condition of heat treatment process and foaming agent, there was the a correlation. An organic type foaming agent like DSS (dioctyl sodium sulfosuccinte) was effective in foaming of the slurry compound consisting of the expanded perlite and sepiolite fiber.

• Fashion & Textile Research Journal
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• v.25 no.6
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• pp.673-689
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• 2023

To realize the traceability of sustainable textile products, this study presents a low-carbon process through energy savings in the textile material manufacturing process. Traceability is becoming an important element of Life Cycle Assessment (LCA), which confirms the eco-friendliness of textile products as well as supply chain information. Textile products with complex manufacturing processes require traceability of each step of the process to calculate carbon emissions and power usage. Additionally, an understanding of the characteristics of the product planning-manufacturing-distribution process and an overall understanding of carbon emissions sources are required. Energy use in the textile material manufacturing stage produces the largest amount of carbon dioxide, and the amount of carbon emitted from processes such as dyeing, weaving and knitting can be calculated. Energy saving methods include efficiency improvement and energy recycling, and carbon dioxide emissions can be reduced through waste heat recovery, sensor-based smart systems, and replacement of old facilities. In the dyeing process, which uses a considerable amount of heat energy, LNG, steam can be saved by using "heat exchangers," "condensate management traps," and "tenter exhaust fan controllers." In weaving and knitting processes, which use a considerable amount of electrical energy, about 10- 20% of energy can be saved by using old compressors and motors.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.6
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• pp.29-35
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• 2020

Transition Nozzles are used in industrial air-cooled heat exchangers and widely used in industrial sites as an important component in the heat energy transfer between a heat source and an actuating fluid. There is a worldwide demand for transition nozzles with various materials and shapes, depending on the use environment. This paper aims to improve the transition nozzle forging process suitable for the production of many varieties using Steps 1 to 6 of the TRIZ Methodology for Problem Solving. By utilizing the TRIZ Methodology, this study derives a method to design a variable mold, which is more efficient and can reduce costs compared with having to use several molds. To verify the suitability of the methods derived using the TRIZ technique, a forging analysis is performed on a transition nozzle using DEFORMⓇ, a commercial program for plasticity analysis, and the nozzle material is evaluated for damage as a result of deformation of the transition nozzle thickness. The derived methods can be applied to transition nozzle formation equipment to improve the efficiency of the formation process.

• Proceedings of the KSME Conference
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• 2001.06c
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• pp.525-530
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• 2001

As a part of efforts to examine feasibility of warm forging near-net-shape process for non-heat-treated steel to replace quenched and tempered S45C steel, the optimized process condition has been determined to be $820^{\circ}C$ for heating, 10/sec for strain rate of forging and approximately 250MPa for flow stress from observed results such as the $A_{3}$ transformation temperature of about $790^{\circ}C$, the fully dynamic recrystallized behavior between $800^{\circ}C\;and\;850^{\circ}C$ when compressed up to 63% engineering strain at 10/sec strain rate, and the high temperature microsturctural stability. Also, controlled cooling rate of $6.3^{\circ}C/sec$ by water-spraying at a rate of $0.10cc/sec-cm^{2}$ for 60seconds followed by air-cooling right after forging process has been considered in this study as a feasible approach based on examination of the microsturcture of mixed ${\alpha}-ferrite$ and pearlite, the hardness and tensile properties meeting specification, and the reduced total cooling time to room temperature. Successive works would be carried out for the impact strength, machinalility, and forgeability at this process in the near future.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.96-101
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• 2004

Conventionally, SMAW process was applied to join pipes of RCL, which caused lot of loss in time and cost due to excessive heat input and defects in joining section. Recently, narrow-gap welding(NGW) process was introduced to overcome the disadvantages of SMAW. However, the application of NGW to nuclear power plant is not yet common because safety of NGW process is not proven. In present paper, the welded coupons are made of carbon steel. They are manufactured under different processes; general welding(GW), post-weld heat treatment(PWHT) after GW, repair welding after GW and PWHT with repair welding after GW in carbon steel. Performed are various mechanical tests investigation of microstructure, hardness test, tensile test at room and high temperature, bending test, impact test and J-R test. It is verified that the mechanical properties of carbon steel are greatly changed after repair welding process due to applied heat flux, and that the effect of PWHT is beneficial.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.292-292
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• 2000

Since high-power CO$_2$ Laser can be make a high densed energy to Local processing area, manufacturing processes using the laser can be processed for very Localized areas at a very fast rate with minimal or no distortion. Accordingly, the laser has been widely used in the fields of thermal manufacturing processes such as welding, fusion cutting, grooving, and heat treatment of metals. In particular, interest in the laser heat treatment process has grown tremendously in the past few years. In this process, maintaining the uniform hardening depth is important problem to obtain good quality products and to reduce heat induced distortion and residual stress. For achieving this objective, we introduced a new design technique of a fuzzy logic controller that greatly simplified the design procedure by defining several simplified design parameters. In the design procedure, the major design parameters of the controller are characterized by identifying several common aspects. From a series of simulation results, we found that the proposed design technique can be effectively used to design of a fuzzy logic controller for the LASER surface hardening process.

• Journal of Welding and Joining
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• v.15 no.6
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• pp.49-56
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• 1997

Effect of process parameters on the quality of condenser discharge weld for coated sheet steels was discussed. The welding specimens were coated with pure Zn of 20/20 g/m2 in the production line. Direct measurements of welding parameters such as the discharge current, the pressures and the voltage drop across the electrodes were carried out with welding process monitoring system. High speed camera was also utilized to analyze the weld formation process. Test results indicated that the relation between weld strength and applied energy was stabilized at the acceptable welding heat input range. It was thought that the acceptable welding heat input should be redefined based on the monitored data because the calculated value of the welding heat input could hardly be utilized if the discharge condition was changed. Mechanical test results and high speed photographs showed that expulsion deteriorated the weld quality and the strength at the same time especially when the size of the spatter was large enough to carry the molten metal, which should form the nugget, out of the welding spot. Results also demonstrated that the discharge current should be applied at the appropriate time during the process because sufficient nugget was not produced if the time was deviated from the optimum range.

• Korean Journal of Materials Research
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• v.19 no.4
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• pp.207-211
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• 2009

In this study, we attempted to develop a convenient aluminizing process, using Al-Ti mixed slurry as an aluminum source, to control the Al content of the aluminized layer as a result of a one-step process and can be widely adopted for coating complex-shaped components. The aluminizing process was carried out by the heat treatment on disc and rod shaped S45C steel substrates with Al-Ti mixed slurries that were composed of various mixed ratios (wt%) of Al and Ti powders. The surface of the resultant aluminized layer was relatively smooth with no obvious cracks. The aluminized layers mainly contain an Fe-Al compound as the bulk phase. However, the Al concentration and the thickness of the aluminized layer gradually decrease as the Ti proportion among Al-Ti mixed slurries increases. It has also been shown that the Al-Ti compound layer, which formed on the substrate during heat treatment, easily separates from the substrate. In addition, the incorporation of Ti into the substrate surface during heat treatment was not observed.

• International Journal of Naval Architecture and Ocean Engineering
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• v.10 no.2
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• pp.141-152
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• 2018

The heating process such as line heating, triangular heating and so on is widely used in plate forming of shell plates found in bow and stern area of outer shell in a ship. Local shrinkage during heating process is main physical phenomenon used in plate forming process. As it is well appreciated, the heated plate undergoes the change in material and mechanical properties around heated area due to the harsh thermal process. It is, therefore, important to investigate the changes of physical and mechanical properties due to heating process in order to use them plate the design stage of shell plates. This study is concerned with the development of formula of plastic hardening constitutive equation for steel plate on which line heating is applied. In this study the stress correction formula for the heated plate has been developed based on the numerical simulation of tension test with varying plate thickness and heating speed through the regression analysis of multiple variable case. It has been seen the developed formula shows very good agreement with results of numerical simulation. This paper ends with usefulness of the present formula in examining the structural characteristic of ship's hull.