• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.06a
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• pp.339-340
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• 2008

• Journal of Electrical Engineering and Technology
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• v.1 no.4
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• pp.455-460
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• 2006

This paper presents the convergency property of the Auxiliary Problem Principle when it is applied to large-scale Optimal Power Flow problems with Distributed or Parallel computation features. The key features and factors affecting the convergence ratio and solution stability of APP are also analyzed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.11a
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• pp.657-658
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• 2010

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.1
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• pp.36-44
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• 2005

Nowadays, various kind of rubber-like materials are used in industry. These are usually installed in automobiles, trains, etc. They work as dampers or important parts in the system, and the applications for rubber-like materials are increasing. In the past days, rubber engineers and designers predicted rubber material behaviors by the analytic method for limited problems. With the progress of digital computers, Finite Element Methods is widely used for analyzing the rubber-like materials. The popular methods predicting rubber material property are curve fitting and least square method, but there are some problems such as low precision and tedious solving process. Here, we introduce a method estimating rubber material property by successive zooming genetic algorithm(SZGA). The proposed algorithm offers more precise rubber property. To demonstrate the effectiveness of the proposed algorithm, we compared this method with Haines & Wilson's method, MARC, ABAQUS.

• Textile Coloration and Finishing
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• v.24 no.1
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• pp.91-96
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• 2012

The physical properties of recycled polyester yarns according to recycling methods were investigated. Virgin polyester draw texturized yarn(DTY), material-recycled(MR) polyester DTY and chemical-recycled(CR) polyester DTY were prepared. Surface morphology, thermal property, micro-structure and mechanical property of recycled polyester yarns were estimated. SEM-EDS analysis showed that the CR PET yarn had better crimp and more stable structure than MR PET yarn. Tm of the MR PET yarn was higher than that of the CR PET yarn. The intensity of the crystallization peak of the CR PET yarn was a little higher than that of the MR PET yarn. Tensile strength of the MR PET yarn was slightly higher than that of the CR PET yarn. Breaking elongation of the CR PET yarn was slightly higher than that of the MR PET yarn.

• Journal of Adhesion and Interface
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• v.6 no.4
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• pp.12-17
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• 2005

Natural fiber/phenolic biocomposites with chopped henequen fibers treated at various levels of electron beam irradiation (EBI) were made by means of a matched-die compression molding method. The interfacial property was explored in terms of interfacial shear strength measured by a single fiber microbonding test. The thermal properties were studied in terms of storage modulus, tan ${\delta}$, thermal expansion and thermal stability measured by dynamic mechanical analysis, thermomechanical analysis and thermogravimetric analysis, respectively. The result showed that the interfacial and thermal properties depend on the treatment level of EBI done to the henequen fiber surfaces. The present result also demonstrates that 10 kGy EBI is most preferable to physically modify the henequen fiber surfaces and then to improve the interfacial property of the biocomposite, supporting earlier results studied with henequen/poly (butylene succinate) and henequen/unsaturated polyester biocomposites.

• Composites Research
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• v.36 no.2
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• pp.86-91
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• 2023

Thermoplastic polyurethane (TPU) is a material whose mechanical properties change according to the phase separation of its unique internal microstructure and is therefore used in various industries. Use of TPU as composites helps in improving the desirable characteristics and properties in accordance with usage. Eco-friendly fillers one of the fillers are on the rise and those are mostly used for reinforcing role. Suberin, which can be extracted from cork, is the main component of cork. It is known to serve high damping property of elastomer composite. The original chemical structure of Suberin is an aliphatic polyester aggregate. In this research, Suberin is obtained after depolymerization into an oligomer having 2 or 3 ester bonds through alkaline hydrolysis. The extracted suberin was added to the matrix which is thermoplastic polyurethane as an eco-friendly filler for improving vibration damping property. As a result, when 10 wt% of suberin was added into thermoplastic polyurethane the existing trade-off relationship was overcome. And it is attained the elastic modulus and damping factor at room temperature improving 92 and 59%, respectively, compared to the original matrix. Those results are from the interaction between the microstructure of TPU and suberin.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.19 no.3
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• pp.135-143
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• 2009

To study possibility of $Cr^{6+}$ solid solution and efficiency of admixture, leaching property of Portland cement mortar was investigated by using KSLT (Korea Standard Leaching Test), TCLP (Toxicity Characteristic Leaching Procedure), Soacking procedure, as adding excess $Cr^{6+}$. As a result, admixture of lignin type showed high compressive strength of mortar but no changing leaching property.

• Journal of Power System Engineering
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• v.15 no.1
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• pp.45-50
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• 2011

The effect of Mn and Ti contents in filler wire on the microstructure and mechanical property of weld metal has been investigated after hybrid welding with ultra fine grained (UFG) steel. The microstructure and distribution of alloy compositions at the top region of weld zone were quite different with those at the bottom region after hybrid welding. The bottom region of weld zone contained higher Mn and Ti contents, and consequently the hardness of bottom region was higher than that of top region. With the increase of Mn and Ti contents in filler wire, the volume percent of acicular ferrite in weld metal decreased, and the weld zone showed higher hardness and better impact property.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.217-222
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• 2004

The aim of this paper is to investigate the effect of micro-dimple size on reduction friction and to understand the potential of friction reduction through micro-scale dimple to fabricate by photolithography on pin-on-disk test using flat-on-flat contact geometry. It was verify that the friction property with respect to the same pitch has been influence on the size of dimple under lubricated sliding contact. Also, we can recognize from Stribeck curve that the friction property has a connection with the size of dimple. It can explain a relationship between the friction coefficient and a dimensionless parameter for lubrication condition. The friction property has been an effect on the size of surface texture on reduction friction, not only because the density of dimple, but also because the ratio of diameter/pitch. This ratio of approximately 0.5 is recommend under the tested friction condition. It suggested that the ratio of d/p is an important parameter for surface texture design.