• Publications of The Korean Astronomical Society
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• v.8 no.1
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• pp.199-206
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• 1993

We review recent systematic investigation of the X-ray spectra of early type galaxies by using the Einstein data base and present new results by the ROSAT observations. The Einstein data suggested that the galaxies with low X-ray to optical luminosity ratio may have another very soft component. ROSAT observations confirm its presence and call for further study to understand the nature of this very soft emission. The X-ray bright galaxies have emission temperature of ${\sim}\;0.8\;keV$ and show radial gradients in the sense that X-ray emission is softer and more absorbed in the inner region.

• Journal of applied mathematics & informatics
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• v.22 no.1_2
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• pp.467-474
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• 2006

We present and study the stability and convergence of a deflation-preconditioned conjugate gradient(PCG) scheme for the interior generalized eigenvalue problem $Ax = {\lambda}Bx$, where A and B are large sparse symmetric positive definite matrices. Numerical experiments are also presented to support our theoretical results.

• Communications of the Korean Mathematical Society
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• v.14 no.2
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• pp.429-440
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• 1999

In this paper an electrochemistry model which consists of three charged species is considered. A dissociation-association reaction is allowed to take place between these species. The species of ions diffuse owing to concentration gradients and migrate because of electric forces. We prove that any initial distribution of species concentrations will settle down to the unique steady state as time becomes large.

• Proceedings of the Korean Fiber Society Conference
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• 2003.10b
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• pp.114-117
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• 2003

Conventional heating the heat source cause the molecules to react from the surface toward the center so that successive layers of molecules heat in turn. The product surfaces may be in danger of over heating by the time heat penetrates the material. Microwave, however, produce a volume heating effect. All molecules are set in action at the same time. It also evens temperature gradients and offers other important benefits such as selective heating. (omitted)

• Journal of The Korean Astronomical Society
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• v.34 no.4
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• pp.289-291
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• 2001

To study the structure and dynamics of a cosmic-ray-plasma system, hydrodynamic approach is a fairly good approximation. In this approach, there are three basic energy transfer mechanisms: work done by the plasma flow against pressure gradients, cosmic ray streaming instability and stochastic acceleration. The interplay between these mechanisms gives a range of structures. We present some results of different version of the hydrodynamic approach, e.g., flow structure, injection, instability, acceleration with and without shocks.

• YAKHAK HOEJI
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• v.27 no.3
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• pp.221-227
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• 1983

New lectins, lymphoagglutinating lectins from mung beans (MBLA) have been isolated and purified. Mung beans crude extracts were made with 0.15M NaCl and these were purified through anionic exchange chromatography. Four fractions were obtained from DEAE Sephadex A-50 by salt gradients elution. Lectin activity, enzyme activity, protein assay, identification of purity by polyacrylamide gel electrphoresis and immunochemical studies were carried out with these four fractions. Through these results, it can be suggested that 0.2M fraction is newly found potent MBLA. There were some relationships with MBLA and L-PHA but no similarities were observed between MBLA and E-PHA.

• Proceedings of the KSR Conference
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• 2002.10b
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• pp.954-961
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• 2002

Ventilation system on passenger rooms should be designed for the health and comfort of the passengers. One of the main aim is to create an acceptable thermal environment without draught problems. The draught sensation increases when the air temperature decreases and the air velocity increases. Airflow in passenger rooms is turbulent. Lateral temperature and humidity gradients in the electric rolling stock have been studied. And, the difference in the mean temperatures measured at 0.7, 0.9, 1.2, 1.7 m above the floor. It has been found that temperature with large fluctuations caused more draught complains.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.10a
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• pp.352-357
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• 1996

In hardening massive concrete, the heat of hydation gives rise to considerable thermal gradientsand thermal stresses, which might cause early age cracking. This paper deals with the results of evaluation of hydration heat of low hear concrete, using Belite rich cement (low heat cement) and compared with OPC, slag added cement and fly ash addedcement. Result of evaluation of hydration are presented in this paper. The concrete made with Belite rich cement gets low temperature of center point and low thermal gradients between surface and center points.

• Proceedings of the Korean Fiber Society Conference
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• 2001.10a
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• pp.403-404
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• 2001

In conventional heating, the heat source causes the molecules to react from the surface toward the center so that successive layers of molecules heat in turn. In the microwave heating, which is produced a volume heating effect, all molecules are set in action at the same time. And, It also evens temperature gradients without the concern of material thickness. (omitted)

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2003.10a
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• pp.383-388
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• 2003

This paper deals with the singular stresses developed in a polymer coating on concrete due to temperature change. The boundary element method is employed to investigate the behavior of interface stresses. Numerical results show that very large stress gradients are present at the interface comer and such stress singularity dominates a very small region relative to layer thickness. Since the exceedingly large stresses at the interface corner cannot be borne by coating materials, local yielding or delamination can occur in the vicinity of free surface.