• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 봄 학술발표회 논문집
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• pp.834-839
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• 2003

Previous research has been conducted on an ultrasonic wave reflection method that utilizes a steel plate embedded in the concrete to measure the reflection loss of shear waves at the steel-concrete interface. The reflection loss has been shown to have a linear relationship to compressive strength at early ages. The presented investigations continue this research by examining the fundamental relationship between the reflection loss, measured with shear waves, and the hydration kinetics of Portland cement mortar, represented by dynamic elastic moduli, compressive strength and degree of hydration. Dynamic elastic moduli are measured by fundamental resonant frequency and degree of hydration is determined by thermogravimetric analysis. The water/cement ratio was varied for the tested mixture compositions. The results presented herein show that compressive strength, dynamic shear modulus and degree of hydration have a linear relationship to the reflection loss for the tested mortars at early ages.

• 한국경영과학회지
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• 제22권1호
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• pp.75-85
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• 1997

A stable algorithm for computing the fundamental matrix (I-Q)$^{-1}$ of a Markov chain is proposed, where Q is a substochastic matrix. The proposed algorithm utilizes the GTH algorithm (Grassmann, Taskar and Heyman, 1985) which is turned out to be stable for finding the steady state distribution of a finite Markov chain. Our algorithm involves no subtractions and therefore loss of significant digits due to concellation is ruled out completely while Gaussian elimination involves subtractions and thus may lead to loss of accuracy due to cancellation. We present numerical evidence to show that our algorithm achieves higher accuracy than the ordinagy Gaussian elimination.

• Journal of Electrical Engineering and Technology
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• 제5권3호
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• pp.484-492
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• 2010

Magnetic switch is a kind of saturable inductor, which utilizes nonlinearity of the magnetization curve of ferromagnetic materials. The right understanding of the saturation phenomena, magnetic properties, voltage-time product, and switching characteristics of the magnetic switch is essential in designing the magnetic pulse compressor (MPC). In this paper, the historical background of research on the MPC, fundamental physical properties of the magnetic switches, and application fields of the MPC are presented. Further, an in-depth analysis of pulse compression in series and parallel MPCs is incorporated. As practical application examples, a series MPC used for water treatments and a parallel MPC used for pulsed electric field (PEF) inactivation of bacteria are cited.

• Food Science and Biotechnology
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• 제14권6호
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• pp.783-787
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• 2005

Fraction (PMEx-AH-${\beta}$) of water-soluble polysaccharide, showing stimulating activity against macrophages, was isolated from mycelia of solid cultured Phellinus linteus by hot-water extraction, ethanol precipitation, and chromatography. Chemical characteristics of PMEx-AH-${\beta}$ were as follows: carbohydrate content, 71%; monosaccharide composition, Man:Glu:Gal (9:64:27); molecular weight, $1-7{\times}10^4$; uronic acid content, 6.8%. Fundamental structure of PMEx-AH-${\beta}$ is deduced as ${\beta}$-($1{$\rightarrow}6$)-D-glucan with ${\beta}$-($1{\rightarow}3$)-D-glucosidic side chains based on methylation analysis.

• International Journal of Naval Architecture and Ocean Engineering
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• 제5권3호
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• pp.392-403
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• 2013

For the analysis of radiating noise problems in medium-to-high frequency ranges, the Energy Flow Boundary Element Method (EFBEM) was developed. EFBEM is the analysis technique that applies the Boundary Element Method (BEM) to Energy Flow Analysis (EFA). The fundamental solutions representing spherical wave property for radiating noise problems in open field and considering the free surface effect in underwater are developed. Also the directivity factor is developed to express wave's directivity patterns in medium-to-high frequency ranges. Indirect EFBEM by using fundamental solutions and fictitious source was applied to open field and underwater noise problems successfully. Through numerical applications, the acoustic energy density distributions due to vibration of a simple plate model and a sphere model were compared with those of commercial code, and the comparison showed good agreement in the level and pattern of the energy density distributions.

• 말소리와 음성과학
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• 제1권1호
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• pp.9-22
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• 2009

This paper first presents the author's personal view on the importance of modeling in scientific research in general, and then describes two of his works toward modeling certain aspects of human speech communication. The first work is concerned with the physiological and physical mechanisms of controlling the voice fundamental frequency of speech, which is an important parameter for expressing information on tone, accent, and intonation. The second work is concerned with the cognitive processes involved in a discrimination test of speech stimuli, which gives rise to the phenomenon of so-called categorical perception. They are meant to illustrate the power of models based on deep understanding and precise formulation of the functions of the mechanisms/processes that underlie observed phenomena. Finally, it also presents the author's view on some models that are yet to be developed.

• 천문학논총
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• 제30권2호
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• pp.363-365
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• 2015

We study galaxies drawn from the semi-analytic models of Guo et al. (2011) based on the Millennium Simulation. We establish a set of four observationally measurable parameters which can be used in combination to identify a subset of galaxy groups which are old, with a very high probability. We therefore argue that a sample of fossil groups selected based on the luminosity gap will result in a contaminated sample of old galaxy groups. By adding constraints on the luminosity of the brightest galaxy, and its offset from the group luminosity centroid, we can considerably improve the age-dating.

• Elastomers and Composites
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• 제18권3호
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• pp.87-98
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• 1983

Fundamental properties and surface treatment effects of domestic kaolin calcined at higher temperature were studied to develop reinforcing fillers for rubbers. The results obtained are as follows: (i) X-ray diffraction and scanning electron microscopy studies revealed kaolinite as a major constituent of the raw kaolin used in this study. (ii) Physical properties of natural rubber vulcanizates compounded with the calcined kaolin fillers treated with poly(maleic anhydride) and sodium polyphosphate are favorably improved. Particularly, the kaolin filler treated with sodium polyphosphate(designated as PT series) shows excellent physical properties compared with hydrated silica.

• Food Science and Biotechnology
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• 제18권3호
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• pp.667-671
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• 2009

Extract of water-soluble polysaccharide (CFWx), showing inhibiting activity on ${\alpha}-glucosidase$, was prepared from the fruiting bodies of Cordyceps militaris by hot-water extraction, and ethanol precipitation. Chemical characteristics of CFWx were as follows: carbohydrate content 30% including 16% of uronic acid; 51% protein content; monosaccharide composition, Man:Glu:Gal (30:43:27); molecular weight $3-5{\times}10^4$. CFWx was further purified by ion-exchange, gel-permeation, and affinity chromatography and $CFWx-AH-{\alpha}$ fraction was isolated. Fundamental structure of $CFWx-AH-{\alpha}$ was deduced as ${\alpha}-(1{\to}4$)-D-glucan with ${\alpha}-(1{\to}3$)- and/or ${\alpha}-(1{\to}6$)-D-glycosidic side chains based on methylation analysis.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1990년도 가을 학술발표회 논문집
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• pp.157-162
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• 1990

Recently, the multistory building construction of reinforced concrete has increased year by year, trended to be high rise in the view of effective land use planning, costing down of building construction and residential conditions. For this urgent need in construction industry, research and development of workability and engineering properties of high strength concrete has been closed up as one of the big world wide problems to be solved reasonably. It is aim of this study to provide the fundamental data the workability and engineering properties of steel-fiber reinforced high strength concrete containing silica-fume and fly-ash comparing with plain concrete for the practical use and research data accumulation in the side of development of new material in the building construction.