• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.1
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• pp.90-94
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• 2022

Metal 3D-printing technology enables the manufacture of complex features or internal structures, which is not possible in fabrication by conventional cutting methods. The most successful types of metal 3D printing have been powder bed diffusion and directed energy deposition, which use laser heads exploiting high-power laser sintering metal powder. In this study, a cost-effective optical design was proposed for a 2-kW-level fiber laser head. Only two commercial lenses, a beamsplitter and a window, are used in the laser head, satisfying the technological requirements. According to the optical design, the spot size was 2.54 mm, and the stand-off distance from the laser head was 295 mm. The intensity distribution was Gaussian. Thus, smooth power sintering was possible without any laser spot marks. Monte Carlo analysis was employed to verify the consistency of the optical performance under conventional assembly tolerance.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.17 no.2
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• pp.75-82
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• 2021

The 3D printing technology is one of the fourth industrial revolution technology that drives innovation in the manufacturing process, and should be applied to nuclear industry for various purposes according to the manufacturing trend change. In nuclear industry, it can be applied to manufacture obsolete items and new designed parts in advanced reactors or small modular reactors (SMRs), replacing the traditional manufacturing technologies. A gate valve body was manufactured, which was obsolete in nuclear power plant, using DED(Directed Energy Deposition) metal 3D printing technology after restoring design characteristics including 3D design drawing by reverse engineering. The 3D printed valve body was assembled with commercial parts such as seat-ring, disk, stem, and actuator for performance test. For the valve assembly, including 3D printed valve body, several tests were performed, including pressure test, end-loading test, and seismic test according to KEPIC MGG and KEPIC MFC. In the pressure test, hydraulic pressure of 391kgf/cm² was applied to 3D printed valve body, and no leak was detected. Also the 3D printed valve assembly was performed well in end-loading and seismic tests.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.19 no.1
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• pp.11-19
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• 2023

Additive manufacturing technology, called as 3D printing, is one of fourth industrial revolution technologies that can drive innovation in the manufacturing process, and thus should be applied to nuclear industry for various purposes according to the manufacturing trend change in the future. In this paper, we performed tensile tests of 3D printed stainless steel 316L as-built specimens manufactured by two types of technology; DED (Directed Energy Deposition) and PBF (Powder Bed Fusion). Their mechanical properties (tensile strength, yield strength, elongation and reduction of area) were compared. As a result of comparison, the mechanical properties of the PBF specimens were slightly better than those of DED specimens. In the same additive type of specimens, the tensile and yield strength of specimens in the X and Y direction were higher than those in the Z direction, but the elongation and ROA were lower.

• Asian-Australasian Journal of Animal Sciences
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• v.14 no.5
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• pp.720-732
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• 2001

Skeletal muscle is of major economic importance since it is finally converted to meat for consumers. The increase in meat production with low costs of production may be achieved by optimizing muscle growth, whereas a high meat quality requires, among other factors, the optimization of intramuscular glycogen and fat stores. Thus, research in energy metabolism aims at controling muscle metabolism, but also liver and adipose tissue metabolism in order to optimize energy partitioning in favour of muscles. Liver is characterized by high anabolic and catabolic rates. Metabolic enzymes are regulated by nutrients through short-term regulation of their activities and long-term regulation of expression of their genes. Consequences of liver metabolic regulation on energy supply to muscles may affect protein deposition (and hence growth) as well as intramuscular energy stores. Adipose tissues are important body reserves of triglycerides, which result from the balance between lipogenesis and lipolysis. Both processes depend on the feeding level and on the nature of nutrients, which indirectly affect energy delivery to muscles. In muscles, the regulation of rate-limiting nutrient transporters, of metabolic enzyme activities and of ATP production, as well as the interactions between nutrients affect free energy availability for muscle growth and modify muscle metabolic characteristics which determine meat quality. The growth of tissues and organs, the number and the characteristics of muscle fibers depend, for a great part, on early events during the fetal life. They include variations in quantitative and qualitative nutrient supply to the fetus, and hence in maternal nutrition. During the postnatal life, muscle growth and characteristics are affected by the age and the genetic type of the animals, the feeding level and the diet composition. The latter determines the nature of available nutrients and the rate of nutrient delivery to tissues, thereby regulating metabolism. Physical activity at pasture also favours the orientation of muscle metabolism, towards the oxidative type. Consequently, breeding systems may be of a great importance during the postnatal life. Research is now directed towards the determination of individual tissue and organ energy requirements, a better knowledge of nutrient partitioning between and within organs and tissues. The discovery of new molecules (e. g. leptin), of new molecular mechanisms and of more powerful techniques (DNA chips) will help to achieve these objectives. The integration of the different levels of knowledge will finally allow scientists to formulate new types of diets adapted to sustain a production of high quality meat with lower costs of production.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.3
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• pp.12-21
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• 2022

Directed energy deposition (DED) was adopted as a metal additive manufacturing method to develop a mold for the hot stamping process. The test piece was machined from Heatvar laminate material, and results were obtained through microstructure and defect observations, as well as hardness, tensile strength, and joint strength tests. 1) Spherical pores and irregular-shaped cavities were observed as lamination defects, and columnar dendrites formed in the structure, which tended to become coarse upon heat treatment. 2) The hardness of the heat-treated material (480HV) was slightly lower than that of the non-heat-treated material (500HV). 3) In the tensile test, the maximum tensile stress and strain of the heat-treated material were 1392 MPa and 15%, respectively, which were slightly higher than the values of 1381 MPa and 13%, respectively, for the non-heat-treated material. 4) In the case of the early final fracture in the tensile test, in most cases, pores or irregularly shaped cavities were observed at the fracture surface or near the surface. 5) In the joint strength test, most of the specimens finally fractured in the laminated metal area, and the fracture surface was intragranular. In addition, dimples formed over the entire area on the fracture surface of the fractured specimen after sufficient elongation.