• 한국소음진동공학회논문집
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• 제19권4호
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• pp.363-369
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• 2009

A vibration analysis for a rotating cantilever beam with the tapered cross section is presented in this study. The stiffness changes due to the stretching caused by centrifugal inertia forces when a tapered cantilever beam rotates about the axis perpendicular to its longitudinal axis. When the cross section of cantilever beam are assumed to decrease constantly, the mass and stiffness also change according to the variation of the thickness and width ratio of a tapered cantilever beam. Such phenomena result in variations of natural frequencies and mode shapes. Therefore it is important to the equations of motion in order to be obtained accurate predictions of these variations. The equations of motion of a rotating tapered cantilever beam are derived by using hybrid deformation variable modeling method and numerical results are obtained along with the angular velocity and the thickness and width ratio.

• 한국언어정보학회지:언어와정보
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• 제4권1호
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• pp.97-109
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• 2000

Application systems of natural language processing such as machine translation system must deal with actual texts including the full range of linguistic phenomena. But it seems to be impossible that the existing grammar covers completely such actual texts because they include disruptive factors such as long sentences, unexpected sentence patterns and erroneous input to obstruct well-formed analysis of a sentence. In order to solve analysis failure due to the disruptive factors or incorrect selection of correct parse tree among forest parse trees, this paper proposes two-level computational grammar which consists of a constraint-based grammar and an error-tolerant grammar. The constraint-based computational grammar is the grammar that gives us the well-formed analysis of English texts. The error-tolerant computational grammar is the grammar that reconstructs a comprehensible whole sentence structure with partially successful parse trees within failed parsing results.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 추계학술대회 논문집
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• pp.573-576
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• 2007

가스 하이드레이트의 구조-I 및 구조-H의 공존 현상을 13C NMR과 Raman spectroscopy를 이용하여 분석하였다. 하이드레이트 생성 조건이 구조-H 영역에만 있을 때는 CH4+neohexane 혼합 하이드레이트가 구조-H만을 나타냈지만, 구조-I의 영역에서는 구조-H의 혼합 하이드레이트와 구조-I의 순수 메탄 하이드레이트가 공존하는 것을 $^{13}C$ NMR spectra를 통해 확인하였다. 이러한 현상은 구조-H 생성자로 알려진 isopentane, MCP, MCH 에서도 관찰되었으며, Raman spectroscopy를 이용해서도 확인할 수 있었다.

• 대한한방내과학회지
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• 제19권1호
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• pp.477-487
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• 1998

To clarify the activating effects of Scolopendrae corpus on immunological function, its effect on primary and secondary antibodies production in mice of various ages was investigated. Scolopendrae corpus increased the number of both antibody producing cells(anti-IgM and anti-IgG producing plaque forming cells, PFC) and phagocytic activity of peritoneal macrophage. Futhermore, these phenomena were significantly increased with aging in mice. Scolopendrae corpus also increased natural killer cell activity concerning to cancer immunology. These results suggest that Scolopendrae corpus markedly increases the reduced activity in the elderly and activates the immune response in senescence mice.

• 한국세라믹학회지
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• 제17권3호
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• pp.151-157
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• 1980

Crystallization phenomena of glasses of fused natural basalt rocks were studied by DTA, X-ray phase analysis, electron microscopy, and other techniques. Crystallization was catalyzed by the addition of either chromite ore or $P_2O_5$, both up to 5 wt %. Various heat treatments were used, and their influences on controlling the microstructures and properties of the products were studied to develop high strength glass-ceramic material of the $CaO-Al_2O_3(Fe_2O_3)-MgO(FeO)-SiO_2$ system from the domestic basalts. Magnetite precipitates were found to be a nucleation initiator in every case of the crystallization. Diopside, anorthite, clinoenstatite and monticellite were identified as silicate crystalline phases contained in the crystallized products. The crystallite size was in the range of 0.1-2.5$\mu\textrm{m}$. The fine crystallites were approximately cubic, but large crystallites were either plate or needle shape. The thermal expansion coefficient, microhardness and modulus of rupture of glass-ceramics were ranged from 78.5 to 81.8$\times$10-7 cm/cm/$^{\circ}C$, from 820 to 930kg/$\textrm{mm}^2$, and from 1800 to 2800kg/$\textrm{cm}^2$, respectively.

• 한국안전학회지
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• 제15권1호
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• pp.36-42
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• 2000

An experimental study was carried out to investigate the effects of inclined angles of channel on thermal stability of electronic components. In this study, it is focused on the natural convection heat transfer from an inclined parallel channel with discrete protruding heat sources. The material used for the inclined parallel channel was epoxy-resin, while air as the cooling fluid. Heat transfer phenomena for inclined angles of $\psi$=$15^{\circ}$, $30^{\circ}$, $45^{\circ}$, $60^{\circ}$ and for the range of $9.52{\times}10^5/ were analyzed. The thermal fields in the channel were visualized by Mach-Zehnder interferometer. Also, local temperatures were measured by thermocouples along the channel wall and heat sources surface. As a result, for the range of $4.29{\times} 10^5/, a useful correlation of mean Nusselt number was proposed as a function of modified channel Rayleigh number.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2011년 춘계학술대회논문집
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• pp.259-260
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• 2011

Using modern techniques from scientific computing and numerical analysis, natural phenomena or scientific experiment can be simulated effectively with a computer and used for computer graphics, for example as special effects for the film industry, manufacturing the thin film, multi-phase simulation and image processing. The Level Set method can make those things happen without a lot of difficulties. This method was devised by Osher and Sethian(1988) to represent dynamically moving interfaces as the zero level set of a scalar function that evolves in time. Since then, many researchers have worked on many applications using a Level Set Method. I will give a talk about the applications of the Level Set Method.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2011년 춘계학술대회논문집
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• pp.112-116
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• 2011

In this paper, a preconverter of MCFC for an emergence electric power supplier is numerically simulated to increase the hydrogen production from natural gas (methane). Commercial code is used to simulated the porous catalyst with user subroutine to model three dominant chemical reactions which are Stream Reforming(SR), Water-Gas Shift(WGS), and Direct Stram Reforming(DSR). To get 10% fuel conversion rate in preconverter. the required external heat flux is supplied from outer wall of preconverter. The calculated results show that very nonuniform temperature distribution and chemical reaction happen near the wall of preconverter. These phenomena can be explained by the low heat conductivity of porous catalyst and the endothermic reforming reaction.

• 대한기계학회논문집
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• 제19권7호
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• pp.1709-1719
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• 1995

The primary objective of the paper is to obtain the basic information of the natural convection of a stratified with various parametric conditions related to rotating speed, temperature and concentration gradient. For the purpose of it, experiments are performed in a stably stratified salt-water solution with lateral heating in a stationary or rotating annulus. The experiment covers the ranges of Ar=2, Le=100, R $a_{\ta}$=2 10$^{5}$ and Ta=0, 10$^{5}$ - 2.5*10$^{8}$ . Many interesting flow phenomena are observed and rotation effects are examined. Particularly as Taylor number increases (rotation increases) at a given R $a_{\ta}$, the generation of rolls at hot wall is inhibited and the formation and merging process of layers are delayed.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.408-409
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• 2008

This paper presents a new development for topology optimization of heat-dissipating structure with forced convection. To cool down electric devices or machines, two types of convection models have been widely used: Natural convection model with a large Archimedes number and Forced convection with a small Archimedes number. Nowadays, many engineering application areas such as electrochemical conversion device or fuel cell devices adopt the forced convection to transfer generated heat. Therefore, to our knowledge, it becomes an important issue to design flow channels inside which generated heat transfer. Thus, this paper studies optimal topological designs considering fluid-heat interaction. To consider the effect of the advection in the heat transfer problem, the incompressible Navier-stokes equation is solved. This paper numerically studies the coupling phenomena and presents optimal channel design considering forced convection.