• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.12
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• pp.1813-1819
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• 2012

This paper presents vector magnetic properties of an electrical steel sheet (ESS) employed for electric machine and iron loss analysis considering the vector magnetic properties of the ESS. The vector magnetic properties of the ESS are measured by using a two-dimensional single sheet tester and modeled by an E&S vector hysteresis model to be applied to finite element method. The finite element analysis considering the vector magnetic properties is applied to iron loss analysis of a three-phase induction motor model, and the influences of the vector magnetic properties on the iron loss distribution are verified by comparing with numerical results from a typical B-H curve model.

• The Korean Journal of Applied Statistics
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• v.22 no.5
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• pp.943-960
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• 2009

This study suggests an algorithm for generating TMY(typical meteorological year) for the Korean peninsula, and generates the TMY based on the algorithm using 11 years(1998~2008) wind data observed at 77 sites of Regional Meteorological Offices(RMO). The algorithm consists of computing TMM scores based on the various statistics defined by the Fikenstein-Shafer statistical model and, in turn, generating TMY based on the TMM scores. Also the algorithm has two stages designed to yield the best representation of the regional wind characteristics appeared during the 11 years(1998~2008). The first stage is designed for the representation of each of 77 regions of RMO and the second is for the Korean peninsula. Various comparison studies are provided to demonstrate the properties of the TMY like its utility and typicality.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.50 no.3
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• pp.186-190
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• 2005

This experiment was conducted to collect the basic information on the varietal diversity in amylogram properties of 3 different rice sub-species under tropical conditions in IRRI 2001 wet season based upon correlation and principal component analysis. The peak viscosity and breakdown property of Tongil type, i.e.; temperate Indica species showed higher similarity with Japonica type species rather than typical Indica and tropical japonica types. The amylogram properties such as final viscosity, pasting consistency and setback of Tongil type varieties were lower than those of typical Indica and tropical japonica types. The peak viscosity showed positive correlation with trough, while the breakdown showed negative correlation with setback in all tested 3 rice subspecies. The first principal component was applicable to increase the gelatinization temperature, final viscosity, pasting consistency and setback, and applicable to decrease the peak viscosity and breakdown. Varietal classification by the principal component score of each pedigree could be applied to the interpretation of the community by the scatter diagram for the amylogram properties to the different sub-species of rice at IRRI conditions.

• KSTLE International Journal
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• v.6 no.1
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• pp.8-12
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• 2005

The electrorheological properties pertaining to the electrorheological (ER) bebaviour of chitin and chitosan suspensions in silicone oil were investigated. Chitosan suspension showed a typical ER response (Bingham flow behavior) upon application of an electric field, while chitin suspension acted as a Newtonian fluid. The difference in behaior results from the difference in the conductivity of the chitin and chitosan particles, even though they have a similar chemical structure. The shear stress for the chitosan suspension exhibited a linear dependence on the volume fraction of particles and a 1.18 power of the electric field. The experimental results for the chitosan suspension correlated with the conduction model for ER response.

• KSTLE International Journal
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• v.4 no.1
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• pp.14-17
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• 2003

The electrical and rheological properties of a chitosan malonate suspension in silicone oil was investigated by varying the electric fields, volume fractions of particles, and shear rates, respectively, The chitosan malonate susepnsion showed a typical electrorheological (ER) response caused by the polarizability of an amide polar group and shear yield stress due to the formation of multiple chains upon application of an electric field. The shear stress fur the suspension exhibited a linear dependence on the volume fraction and an electric field power of 1.88. On the basis of the experimental results, the newly synthesized chitosan malonate suspension was found to be an anhydrous ER fluid.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.123-128
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• 2001

The Purpose of this study is to clarify the effect of the monomer ratio on properties of the polymer-modified mortars using methyl methacrylate-butyl acrylate latexes, and to obtain basic data necessary to develop appropriate latexes for cement modifiers. This paper deals with the effect of the monomer ratio on the typical properties of polymer-modified mortars with methyl methacrylate-butyl acrylate latexes. The polymer latex-modified mortars are prepared with 5, 10, IS and 20% of polymer cement ratio respectively, and properties of modified mortars such as water absorption, compressive and flexural strengths, chloride-ion penetration depth are tested. The test results indicate that the monomer ratio is very important factors to characterize the strength properties of polymer-modified mortars, but the water absorption and chloride-ion penetration depth are influenced by polymer-cement ratio rather than monomer ratios.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.7 no.1
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• pp.9-16
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• 2008

It is important not only to reduce the casting defects of piston but also to improvement in the mechanical properties(hardness) of piston for the air compressor. The blow hole is typical casting defects in the conventional cast of aluminium alloy(AC8A-T6) piston. Because of the heat treatment method, mechanical properties of the aluminium alloy for piston was decided on the heat treatment method and cycle. Therefore, we tested on the development of mechanical properties and on the casting defects of piston for the air compressor in accordance with the heat treatment and casting condition. After the heat treatment and casting was carried out as several times, and was compared with the imported piston. As a result of several investigations; microstructure, hardness and casting defects of piston was changed under the influence of the heat treatment and casting method. When the cooling rate was controlled and the uni-cast method used, it bas the same mechanical properties and microstructure.

• Journal of Applied Biological Chemistry
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• v.43 no.4
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• pp.207-210
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• 2000

As a typical example of the screening for a microbial biocatalyst from nature, isolation of nitrilesynthesizing microorganisms, characterization of a new enzyme aldoxime dehydratase, and its function in the aldoxime-nitrile pathway are introduced. Catalytic properties of some of our enzymes were improved through a direct evolutionary approach.

• Applied Chemistry for Engineering
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• v.10 no.8
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• pp.1216-1220
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• 1999

Different amounts of zinc stearate were incorporated as a plasticizer into poly(styrene-co-sodium methacrylate) ionomers prepared by bulk-suspension plymerization and neutralization with sodium hydroxide and effects of the zinc stearate on the thermal and rheological properties were investigated. It was obseved that the crystallization of zinc stearate in the ionomers were partially suppressed depending on the content of ionic moieties. It is postulated that the ionic moieties dissolved zinc stearate and suppressed crystallization of the zinc stearates. We speculated that 0.4~0.6 mole of zinc stearate was dissolved by one mole of the ionic moiety. Poly(styrene-co-sodium methacrylate) containing only the dissolved zinc stearates showed typical rheological properties of homogeneous systems in Cox-Mertz plots. However, poly(styrene-co-sodium methacrylate) containing crystallizable zinc stearates as well as dissolved ones showed typical rheological properties of heterogeneous systems.

• Journal of Korean Society on Water Environment
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• v.23 no.4
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• pp.482-489
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• 2007

Fluorescence properties and carbohydrate content were investigated using ultrafiltrated size fractions of dissolved organic matters (DOM) originated from different sources. The materials included a treated sewage, an algal organic matter, and a soil leachate, all of which are major constituents of dissolved organic matter in a typical urban river. Four different size fractions were separated from the three sources of each DOM. The size distribution demonstrated that a higher molecular weight fraction was more present in soil leachate compared to two other source DOMs. A higher content of carbohydrates was observed in the following order - algal DOM > treated sewage > soil leachate. A wide range of specific UV absorbance was observed from size fractions of a single source DOM, indicating that aromatic carbon structures are heterogeneously distributed within one source of DOM. The structural heterogeneity was the most pronounced for the soil leachate. The fluorescence index ($F_{450}/F_{500}$) of the treated sewage was similar to that (2.0) typically obtained from autochthonous DOM, suggesting that the treated sewage exhibited autochthonous organic matter-like properties. No protein-like fluorescence intensities were observed for all of the soil leachate size fractions whereas they were observed with two other source DOMs. Based upon the fluorescence peak ratios from fluorescence excitation-emission matrix (EEM), two discrimination indices could be suggested to distinguish three different source DOMs. It is expected that the suggested discrimination indices will be useful to predict the sources of DOM in a typical urban river affected by treated sewage.