• Journal of Korea Foundry Society
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• v.32 no.5
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• pp.219-224
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• 2012

The effects of Mg and Si contents on the microstructure and mechanical properties in Al-Mg alloy (ALDC6) were investigated. The results showed that phase fraction and size of $Mg_2Si$ and $Al_{15}(Fe,Mn)_3Si_2$ phase in the microstructure of Al-Mg alloy were increased as the Mg and Si contents were raised from 2.5 to 3.5 wt%. With Si content of 1.5 wt%, freezing range of the alloy was significantly reduced and solidification became more complex during the final stage of solidification. While there was no significant influence of Mg contents on mechanical properties, Si contents up to 1.5 wt%, strongly affected the mechanical properties. Especially elongation was reduced by about a half with more than 1.0 wt%Si in the alloy. The bending and impact strength were decreased with increased amount of Si in the alloy, as well. The lowered mechanical properties are because of the growth of particle shaped coarse $Mg_2Si$ phase and precipitation of the needle like $\beta$-AlFeSi in the microstructure at the last region to solidify due to presence of excess amount of Si in the alloy.

• Journal of Welding and Joining
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• v.30 no.5
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• pp.34-39
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• 2012

This study was conducted to investigate the microstructure and mechanical properties of friction stir lap joints. Invar 42 and SS 400 were selected as the experimental materials, and friction stir welding was carried out at a tool rotation speed of 200 rpm and welding speed of 100 mm/min. The application of friction stir welding to Invar 42 effectively reduced the grain size in the stir zone; the average grain size of Invar 42 was reduced from $11.5{\mu}m$ in the base material to $6.4{\mu}m$ in the stir zone, which resulted in an improvement in the mechanical properties of the stir zone. The joint interface between Invar 42 and SS 400 showed a relatively sound weld without voids and cracks, and the intermetallic compounds with $L1_2$ type in lap jointed interface were partially formed with size of 100 nm. Moreover, the hook in the advancing side of Invar 42 was formed from SS 400, which contributed to maintenance of the tensile strength. The evolution of microstructures and mechanical properties of friction stir lap jointed Invar 42 and SS 400 are also discussed herein.

• Journal of Powder Materials
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• v.14 no.5
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• pp.298-302
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• 2007

In recent years, a rapid increase in demands for the soft magnetic composite parts has been created and it has been tried to improve their properties by various processing methods, alloying elements and compaction parameters. Warm compaction method has been used for the reduction of residual stress, the improvement of magnetic properties and the higher densities. In this work, the effects of warm compaction and polymer binder on magnetic properties of Fe powder core were investigated. The sintering powder, Fe oxide, was ball-milled for 30n hours. And then ball-milled Fe oxide powder was reduced through hydrogen reduction process. The hydrogen reduced Fe powder and polymer binder were mixed by 3-D turbular mixer. And then the mixed powder was warm-compacted. The magnetic properties such as core loss and permeability were measured by B-H curve analyzer.

• Food Science and Biotechnology
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• v.18 no.5
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• pp.1138-1144
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• 2009

This study was carried out to investigate the cooking properties and lipid oxidation stability during storage at $4{\pm}1^{\circ}C$ when the various levels (5 to 20%) of doenjang (Korean fermented soybean paste) were added to pork patties cooked by pan frying (PF) and convection oven (CO). With increasing the addition of doenjang, cooking properties of pork patties revealed the improved cooking yield, less diameter reduction, and less thickness increase. Also, the shear force, hardness, and chewiness of pork patties were reduced. The PF cooking method showed better cooking properties than CO. Lipid oxidation expressed by the thiobarbituric acid reactive substances (TBARS) values was significantly reduced by the addition of more than 5% doenjang (p<0.05). The TBARS values of cooked pork patties by PF were significantly lower than CO during the 8 days of the storage (p<0.05). The development of warmed-over flavor (WOF) in cooked pork patties was delayed as the amount of the doenjang was increased. It was suggested that the addition of doenjang and PF favorably affected the cooking properties and stability of lipid oxidation in pork patties.

• The Pure and Applied Mathematics
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• v.17 no.2
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• pp.131-136
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• 2010

Throught this paper, we will investigate some properties of left regular and strongly reduced near-rings. Mason introduced the notion of left regularity and he characterized left regular zero-symmetric unital near-rings. Also, this concept have been studied by several authors. The purpose of this paper is to find some characterizations of the strong reducibility in near-rings, and the strong regularity in near-rings which are closely related with strongly reduced near-rings.

• 제어로봇시스템학회:학술대회논문집
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• 1994.10a
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• pp.690-695
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• 1994

We propose a method to reduce the marking expression about the places when we model a discrete-event system using the Petri net. The net with reduced marking expression has the same dynamic behavior as the original model. The number of the places can be reduced by the number of the resource places of the Petri net, and consequently the net can be significantly simplified, still preserving the dynamic properties of the net.

• East Asian mathematical journal
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• v.22 no.1
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• pp.61-69
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• 2006

A near-ring N is reduced if, for $a{\in}N,\;a^2=0$ implies a=0, and N is left strongly regular if for all $a{\in}N$ there exists $x{\in}N$ such that $a=xa^2$. Mason introduced this notion and characterized left strongly regular zero-symmetric unital near-rings. Several authors ([2], [5], [7]) studied these properties in near-rings. Reddy and Murty extended some results in Mason to the non-zero symmetric case. In this paper, we will define a concept of strong reducedness and investigate a relation between strongly reduced near-rings and left strongly regular near-rings.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2012.05a
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• pp.235-235
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• 2012

Reduced graphene oxide (rGO) 물질을 사용하여 전계효과 트랜지스터를 제작하였고 이의 광전기적 특성을 펄스 레이저와 진공 저온 측정을 통하여 분석하였다. 이를 통하여 rGO 소자의 광소자로써의 이용 가능성에 대하여 고찰하였다.

• Coupled systems mechanics
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• v.7 no.1
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• pp.61-77
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• 2018

This paper establish a high concentration ratio approximation of linear elastic properties of materials with periodic microstructure with cubic inclusions. The approximation is derived using first few terms of power series expansion of the solution of the equivalent eigenstrain problem with a homogeneous eigenstrain approximation. Viability of the approximation at high concentration ratios is proved by comparison with a numerical solution of the homogenization problem. To this end some theoretical result of symmetry properties of the homogenization problem are given. Using these results efficient numerical computation on a reduced computational domain is presented.

• Asian-Australasian Journal of Animal Sciences
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• v.19 no.3
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• pp.450-458
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• 2006

The present study was carried out to investigate the changes in chemical and sensory properties, and cholesterol lowering effect of evening primrose oil (EPO) addition in cholesterol-reduced Cheddar cheese. The cholesterol removal rate reached 92.07% by ${\beta}$-cyclodextrin in the cheese before EPO addition. The thiobarbituric acid (TBA) value of cholesterol-reduced and EPO-added cheese increased with both ripening time and amount of EPO addition. Addition of 5% EPO resulted in a significant difference in TBA value after 4-week ripening, compared with no addition of EPO. The production of short-chain free fatty acids (FFAs) increased with ripening period in all treatments. From 4 week of ripening, the amounts of short-chain FFA in 3 and 5% EPO-added groups were significantly higher than those in other groups. Among sensory characteristics, rancidity was mostly affected by EPO addition, however, the rancidity value of 1% EPO-added was not significantly different from that of EPO-free and cholesterol-reduced cheese. Also, Cheddar cheese flavor was not profoundly affected by 1% EPO addition in all ripening periods. Total blood cholesterol dramatically decreased from 184.0 to 137.1 mg/dL with 5% EPO-added and cholesterol-reduced cheese following 8 weeks of feeding. The present results indicated that 5% EPO addition resulted in a profound lowering effect on blood total cholesterol with some adverse effects on chemical and sensory properties.