• Korean Journal of Metals and Materials
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• v.48 no.3
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• pp.241-247
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• 2010

In order to develop the vacuum distillation process of magnesium alloy scrap, a fundamental study on the evaporation behavior of magnesium alloy (AM50) scrap melt was carried out. Melt temperature, pressure, reaction time, and initial specific surface area of melt were considered as experimental variables. The evaporation rate of magnesium increased with the increase of melt temperature and initial specific surface area of melt, and with the decrease of the pressure. The activation energy of magnesium evaporation reaction calculated by an Arrhenius plot decreased with the decrease of the pressure and with the increase of the initial specific surface area of melt. An empirical equation was derived for the evaporation rate of magnesium from AM50 alloy melt.

• The Korea Journal of Herbology
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• v.38 no.1
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• pp.45-53
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• 2023

Objectives : Network pharmacology-based research is one of useful tool to predict the possible efficacy and molecular mechanisms of natural materials with multi compounds-multi targeting effects. In this study, we investigated the functional underlying mechanisms of Astragalus membranaceus Bunge (AM) on its anti-obesity effects using a network pharmacology analysis. Methods : The constituents of AM were collected from public databases and its target genes were gathered from PubChem database. The target genes of AM were compared with the gene set of obesity to find the correlation. Then, the network was constructed by Cytoscape 3.9.1. and functional enrichment analysis was conducted to predict the most relevant pathway of AM. Results : The result showed that AM network contained the 707 nodes and 6867 edges, and 525 intersecting genes were exhibited between AM and obesity gene set, indicating that high correlation with the effects of AM on obesity. Based on GO biological process and KEGG Pathway, 'Response to lipid', 'Cellular response to lipid', 'Lipid metabolic process', 'Regulation of chemokine production', 'Regulation of lipase activity', 'Chemokine signaling pathway', 'Regulation of lipolysis in adipocytes' and 'PPAR signaling pathway' were predicted as functional pathways of AM on obesity. Conclusions : AM showed high relevance with the lipid metabolism related with the chemokine production and lipolysis pathways. This study could be a basis that AM has promising effects on obesity via network pharmacology analysis.

• Journal of Korea Foundry Society
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• v.30 no.6
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• pp.217-223
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• 2010

Foamed metal has become an attractive material, which has unique physical, thermal, acoustic, damping and mechanical properties, because large amount of pores are distributed in the metal matrix. Therefore, metal foam can be used for the light weight application in automotive, locomotive, aerospace fields. Aluminum foams have been developed successfully and will be employed in the next generation of energy absorption boxes. Magnesium alloys are most eligible candidate to substitute aluminum alloy, especially for lower density and higher damping properties in wide industrial fields. Magnesium alloy foams are expected to be particularly advantageous due to two thirds the density of aluminum. However, foaming magnesium have been weakness of high activity, difficult processing and very dangerous. In order to upgrade this problem, AM50 magnesium alloy which has better characteristic is safe to use through foaming time and alloying element in this study.

• Journal of Korea Foundry Society
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• v.18 no.4
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• pp.364-372
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• 1998

Effects of Si and Ca additions on the mechanical properties of AM60 based Mg alloys have been investigated. Hardness of the AM60 based Mg alloys reached a maximum value after aging for approximately 33 hours but the amount of hardness increase was negligible. The poor age hardening response of the alloys was due to low Al content, which implies that Al content must be >6 wt.% to observe age hardening effect. The tensile and yield strength increased with increasing Al, Si, and Ca content but elongation decreased with increasing Al and Si content. The best mechanical properties obtained in AM 40-2.5Si-0.2Ca alloy after T4 heat treatment were as follows; tensile strength 193.4 MPa, yield strength 79.2 MPa, and elongation 11.2%. High temperature property obtained from creep test was also improved by introducing $Mg_2Si$ which has high hardness, high melting temperature and low thermal expansion coefficient.

• Journal of Korea Foundry Society
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• v.18 no.4
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• pp.383-388
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• 1998

Effects of $CaCN_2$ addition on the grain refinement in the AM60 magnesium ingots were investigated. The effects of the $CaCN_2$ are estimated with different inoculation temperatures, inoculation contents, and holding time to find out the optimum condition. AM60 alloy was melted in the low carbon steel crucible by cylindrical electric furnace under an argon atmosphere. The melting and casting apparatus is specially designed for magnesium alloys. The grain size of AM60 magnesium alloy decreased significantly with an increase in $CaCN_2$ content and, at 0.8 wt% $CaCN_2$ or more, grain size becomes constant at about $85 {\mu}m$. The optimum condition was obtained in the 0.8 wt% $CaCN_2$ for holding molten metal of 30 min. at the temperature of $710^{\circ}C$. The tensile properties of AM60 magnesium alloys were improved due to grain refinement by addition of $CaCN_2$. In the optimum condition, the yield strength, tensile strength and elongation were ${\sigma}_{0.2}=107 MPa$, ${\sigma}_{T.S}=234 MPa$ and e=14.2%. The variation of stress with strain obeyed the relationship of the ${\sigma}=K{\varepsilon}^n$. The strain-hardening exponent, n and strength coefficient, K obtained in the 0.8 wt% $CaCN_2$ added AM 60 magnesium alloy were n=0.21 and K=390 MPa.

• Smart Structures and Systems
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• v.29 no.6
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• pp.767-775
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• 2022

Metal additive manufacturing (AM), also known as metal three-dimensional (3D) printing, produces 3D metal products by repeatedly adding and solidifying metal materials layer by layer. During the metal AM process, products experience repeated local melting and cooling using a laser or electron beam, resulting in product defects, such as warpage, cracks, and internal pores. Such defects adversely affect the final product. This paper proposes the in situ monitoring-based warpage prediction of metal AM products with experimental feature extraction. The temperature profile of the metal AM substrate during the process was experimentally collected. Time-domain features were extracted from the temperature profile, and their relationships to the warpage mechanism were investigated. The standard deviation showed a significant linear correlation with warpage. The findings from this study are expected to contribute to optimizing process parameters for metal AM warpage reduction.

• Korean Journal of Construction Engineering and Management
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• v.23 no.1
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• pp.113-117
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• 2022

Additive manufacturing (AM, also known as 3D printing) technology is digitalized technology, making it easy to predict and manage quality and also, have design freedom ability. With these advantages, AM technology is applied to various industries. In particular, a method of manufacturing buildings and infrastructure with AM technology is being proposed to the construction industry. However, the application of AM technology is restricted due to problems such as insufficient history and quality of technology, lack of construction management methods, and certification of manufacturing products. Therefore, the manufacture of architectural products is implemented with indirect AM technology. In particular, it manufactures formwork using AM and injecting building materials to implement the architectural product. In this study, hybrid type material extrusion AM is used to manufacture large-sized formwork and implement building products. Moreover, we identify factors that can predict productivity and economic feasibility in the additive manufacturing process. As a result, design optimization results are proposed to reduce the production cost and time of architecture buildings.

• Journal of Welding and Joining
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• v.34 no.4
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• pp.9-16
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• 2016

Metal parts are produced by conventional methods such as casting, forging and cutting, extrusion, etc. However, nowadays, with additive manufacturing (AM), it is possible to directly commercialize by means of stacking of equipment to the 3D drawing and use of high precision tools such as laser source. Thus, drawing of materials is an important aspect in delivering good products. AM deals with production of lighter aircraft parts and few more three-dimensional molds, it wish to manufacture special medical parts and want to steadily expand the new market area. The cost of related equipment and materials are still expensive and difficult to obtain on a mass production. However, the ability to make changes and lead the innovation in the paradigm of traditional manufacturing process is still effective. In this paper, we introduce metal AM and the principles of the related devices, metal powder production process, and their application.

• Korean Journal of Materials Research
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• v.7 no.3
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• pp.229-233
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• 1997

Estimation of thermal stability for diglycidy1 ether of bisphenol A(DGEMA)/4, 4'-methylene dianiline (MDA)/pheny1 glycidy1 ether(PGE)-acetamide(AcAm)/carboxy1-terminated acrylonitrile butadiene copolymer (CTBN) system was studied by thermogravimetry(TG) analysis. To get activation energy for thermal degradation, Freeman & Carroll, Kissinger, and Flynn & Wall expressions were used. The activation energy of Freeman & Wall expression was 112.9kj/mol, that of Kissinger expression was 151.5 kj/mol and that of Flynn & Wall was 168.3kj/mol.

• Korean Journal of Medicinal Crop Science
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• v.21 no.4
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• pp.262-267
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• 2013

The purpose of this study was to research for anti-oxidation and anti-wrinkle effects of Acar mono Sap (AM). To cosmetic effect of AM, safety effect (MTT assay), anti-wrinkle effect (elastase, MMP-1 inhibition assay) and anti-oxidant effect (DPPH assay) were measured. When water extract of AM was used for cell viability, it was over 100% at 6% (6 ml/100 ml in phosphate buffer) concentration. AM showed 45.7% elastase inhibition and 23.7% MMP-1 inhibition at 50% (50 ml/100 ml in phosphate buffer) concentration so that it had good anti-wrinkle characteristic. And AM showed 68.9% antioxidation capacity at 50% concentration by using a DPPH assay. Consequently, AM can be used as natural materials or additives for human skin owing to their beneficial biologic functions, including the anti-wrinkle effect, for cosmetic compositions.