• Journal of Powder Materials
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• v.18 no.4
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• pp.332-339
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• 2011

Cemented tungsten carbide has been used in cutting tools and die materials, and is an important industrial material. When the particle size is reduced to ultrafine, the hardness and other mechanical properties are improved remarkably. Ultrafine cemented carbide with high toughness and hardness is now widely used. The objective of this study is synthesis of nanostructured WC-Co powders by liquid phase method of tungstate. The precursor powders were obtained by freezen-drying of aqueous solution of soluble salts, such as ammonium metatungstate, cobalt nitrate. the final compositions were WC-10Co. In the case of liquid phase method, it can be observed synthesis of WC-10Co. The properties of powder produced at various temperature, were estimated from the SEM, BET and C/S analyser.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.10a
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• pp.407-408
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• 2006

• International Journal of Precision Engineering and Manufacturing
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• v.7 no.3
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• pp.39-46
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• 2006

This paper presents an elastic deformation model of a spindle unit (S/U), which takes into account the non-linear properties of high-speed ball bearings (particularly the effect of high rotational speed). For this, a software for the estimation of the S/U elastic deformation properties was developed and intended for use by S/U designers. A computer aided analysis of the model using the developed software was carried out and experiments showed the significant effect of rotational speed, cutting load and bearing axial preload, and showed some new phenomena, from which the criteria for the choice of bearing axial preload is given.

• Journal of Korea Foundry Society
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• v.18 no.4
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• pp.373-382
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• 1998

Particulate reinforced aluminum alloys produced by indirect squeeze casting are difficult to shape by cutting or milling. Therefore near net shape forming of complex shapes is of high economic and technical interest. The complex shape products of $SiC_p/6061$ Al composites are fabricated by the melt-stirring and indirect squeeze casting process. The mold temperatures are $200^{\circ}C$ and $300^{\circ}C$ and applied pressures are 70, 100, and 130 MPa. The volume fractions of the reinforcements are in the range of 5 vol% to 15 vol%. The reinforcement dispersion state are observed using on optical microscope. By employing observed results systematically a correlation is demonstrated among the microstructure, particles behavior, mechanical properties and processing parameters for an optimum melt-stirring(compocasting) and indirect squeeze casting process of MMCs. A procedure to establish the optimum squeeze casting of Al-MMCs is proposed.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1858-1863
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• 2003

The properties of a machine tool greatly affect machining quality since a machine tool has large variance in its features. Machine tool makers want to find best machining condition with the one that they have built. Machine builders need to develop test specimen since it helps finding characteristics of machine tools when the machining properties of the specimen are analyzed. This paper develops test specimen to identify features of the main spindle, the feeding device, and the frame of a machine tool. The specimen is machined with a high speed machine and the features of the machine are analyzed with test items. They are surface roughness, overshoot in axial movement, errors in circular movement, feeding with small movement, and compensational error. This work can improve usability for a machine tool in machining practice.

• Language and Information
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• v.20 no.1
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• pp.1-24
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• 2016

Korean is well-known for its topic-prominent properties. In this paper, we look into several subtypes of topic constructions whose grammatical complexities have received much attention in generative grammar. From a semantic/pragmatic view, topics in Korean can be classified into three different types: aboutness, contrastive, and scene-setting. Meanwhile, syntax can classify topic constructions into two types, depending on whether or not the comment clause following topic has a syntactic gap linked to the topic. In this paper, we review some key properties of these topic constructions in Korean, and suggest that each type is licensed by tight interactions between syntactic and semantic constraints. In particular, the paper tries to offer a Construction Grammar analysis where each grammatical component is interacting in non-modular ways and in which the multiple inheritance network of constructions plays an important role in capturing cross-cutting generalizations of the topic constructions.

• Journal of the Korean Society of Food Science and Nutrition
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• v.27 no.2
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• pp.281-285
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• 1998

For the purpose of improving the qualities of carrot, spinach and cooked rice, the effects of food height(0mm: H0, 5mm: H5, 10mm: H10, 15mm: H15) for microware blanching and reheating on physicochemical properties were investigated. In carrot blanching, color values of each treatment were not different, and cutting forces of microware blanching carrots were decreased as carrot height increased. In spinach blanching, the shape of orignal form was changed as height increased. In cooked rice reheating, H10 had the highest overall acceptance score. Physicochemical properties were changed by food hight of microwave blanching and reheating on food.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.18 no.6
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• pp.658-663
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• 2009

Metal/ceramic composites structures have many attractive properties with great potential for applications that demand high stiffness as well as chemical and biological stability, thermal and electrical insulation. They are currently in use for mechanical and thermal protection in cutting tool and engine parts. Thus, determination of adhesive properties for coating part is one of the most important problems for the extension of the use of coated materials. In this work, bending strength of Functionally Graded Materials(FGM) are evaluated by means of bending strength tester. The graded layer according to the load condition showed the change of the bend strength.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.644-645
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• 2006

TiC-and Ti(C,N)-based cermets are excellent in semi-and final finishing of work piece during cutting operations. Typical microstructure of the cermets is a core/rim structure. The undissolved Ti(C,N) cores contribute to their high hardness while the rim phases, (Ti,M1,M2)(C,N)-type solid solutions, play great roles in enhancing the toughness. In this paper, various ultrafine pre-mixed MeC-Ni powders were synthesized and the powders were sintered or hot pressed after mixing in order to control the size and volume fractions of core and rim phases in the system. This paper will present the factors determining the microstructure along with mechanical properties.

• Journal of Powder Materials
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• v.3 no.3
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• pp.188-195
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• 1996

In recent times the potential application of the high speed steel produced by HIP process for wear resistant and cutting materials are increasing. In this work the microstructure of Anval 30 produced by HIP process was investigated and the effect of WC, TiC addition on microstructure formation and wear properties were studied. After HIP process at 1150 $^{\circ}C$, the original feature of spherical raw powders was not removed and consequently, nonuniform microstructure was formed. However the WC added by simple powder mixture incereased the sinterbility of high speed steel and uniform microstructure formed. The wear characteristics of Anval 30 with carbide addition were tested at RT and $600^{\circ}C$. The uniform microstructure played an more important role in wear resistance as compared with the hardness.