• 한국공작기계학회논문집
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• 제11권1호
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• pp.120-126
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• 2002

The near net shape forging of gears offers significant technical and economic advantages ever other forms of manufacture. These potential benefits can however only be realized by careful die design. This paper describes a computer-based methodology fur achieving this. A Visual-BASIC program has been developed on a rule based system that enables optimal design of the dies taking into account the elastic deflections generated in shrink-fitting the die inserts and that caused by the stresses generated in the forging process. The method also enables the profile of the spark erosion electrode to be determined. An example of the application to forging spur gears is given.

• 한국광학회:학술대회논문집
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• 한국광학회 2000년도 제11회 정기총회 및 00년 동계학술발표회 논문집
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• pp.192-193
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• 2000

We studied the characteristics and fabricated the plano-convex refractive microlenses using the thermal reflow method. The exposed resist was resolved in a standard developing process. The remaining resist of circle pattern was melted in an oven 12$0^{\circ}C$ to 15$0^{\circ}C$. The shape of the melted resist microlenses is ruled by surface tension. Diameter and hight of the fabricated microlenses were 250${\mu}{\textrm}{m}$ to 325${\mu}{\textrm}{m}$ and 15${\mu}{\textrm}{m}$ to 22${\mu}{\textrm}{m}$, respectively. The surface profile was calculated using data curve-fitting method with circle equation. The optical characteristics was analysed using optical simulation program.

• 천문학회보
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• 제35권1호
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• pp.91.2-91.2
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• 2010

We present far-ultraviolet (FUV) observations of comet C/2001 Q4 (NEAT) obtained with Far-ultraviolet Imaging Spectrograph (FIMS, also called SPEAR) around perihelion between 8 and 15 May 2004. Several important emission lines, including S I (1425, 1474 ${\AA}$), C I (1561, 1657 ${\AA}$), CO (1087.9, 1340-1680 ${\AA}$) were detected. Especially, the spectral features of CO are its electronic transitions belongings to the A-X, C-X systems. We also obtained radial profile of S I, C I, H I $Ly{\beta}$ with line fitting from central coma. The production rate of several spectral lines calculated from observed FUV photon flux. FUV spectral images of S I, C I, H I $Ly{\beta}$ emission lines were obtained.

• 천문학회보
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• 제35권2호
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• pp.81.1-81.1
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• 2010

We present a study of five open clusters (Alessi 53, Berkeley 49, Berkeley 84, Czernik 5, Pfleiderer 3) based on ugriz images of the Sloan Digital Sky Survey (SDSS). Physical properties of these clusters are not yet well known. The center and size of these clusters are determined using the radial number density profile. Using the proper motion data, we select the members of the target clusters. We estimate physical parameters of the clusters based on the isochrone fitting in the Color-Magnitude Diagram (CMD) : reddening, distance, and age. The foreground reddening is determined to be E(B-V)=0.71-1.55 mag. The distances to target clusters are derived to be 2.0-4.4 kpc, corresponding to the galactocentric distances of 7.5-11.9 kpc. Their ages are in the range of 280 to 1000 Myr. Their spatial distribution in our Galaxy is similar to that of other intermediate-age open clusters. We find ten blue straggler star candidates in Berkeley 49. This number of blue stragglers is a typical value for the age of Berkeley 49.

• 수산해양기술연구
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• 제33권3호
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• pp.248-258
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• 1997

The analytical solutions of the Fraunhofer Diffraction(FD) theory and the principle for measurement of the dispersion relation of plasma wave is presented. Especially, the method for measurement of low-frequency wave is discussed. The wavenumbers of the density fluctuations are obtained from the curve fitting between the expremental FD profile and theoretical one for each frequency component. In measurement of the wavenumber of the low -frequency region, the information of the wavenumber is easily obtained from the ratio of the intensity at = 0 to the intensity at =0.5. The millimeter wave FD apparatus was designed to measure low-frequency density fluctuations. The determined wavenumbers are in the range of =0.1~ 1.0cm. Thus, the millimeter wave FD method was shown to be useful for the measurement of low-frequency density fluctuations, which are impossible to be measured by using a convention. Thomson scattering. The obtained dispersion relations will be useful information for plasma waves.

• Journal of the Optical Society of Korea
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• 제9권2호
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• pp.49-53
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• 2005

We report a new configuration of a reflection-type confocal scanning optical microscope system for measuring the refractive index profile of an optical waveguide. Several improvements on the earlier design are proposed; a light emitting diode (LED) at 650 nm wavelength instead of a laser diode (LD) or He-Ne laser is used as a light source for better index precision, and a simple longitudinal linear scanning and curve fitting techniques are adapted instead of a servo control for maintaining an optical confocal arrangement. We have obtained spatial resolution of 700 nm and an index precision of $2\times10^{-4}$. To verify the system's capability, the refractive index profiles of a conventional multimode fiber and a home-made four-mode fiber were examined with our proposed measurement method.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 C
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• pp.2297-2299
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• 2005

In this paper, a finite element (FEM) investigation of composite materials is studied. A pemittivity profile of the material is implemented to correspond to the Packing fraction of the physical composite. Curve fitting is applied to the standing wave pattern to determine the effective attenuation coefficient and propagation constant in the composite. The complex permittivity as a function of packing density is then determined. A comparison between the two dimensional and three dimensional measurement simulations is presented. An adaptive scheme is implemented to improve resolution of the finite element particulates.

• Bulletin of the Korean Chemical Society
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• 제15권1호
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• pp.64-74
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• 1994

The nonstoichiometric chalcogenides with NaCl-type structure were prepared and the physical and structural properties were studied. The homogeneous range and the structural change were studied based on X-ray powder diffractions using Rietveld-type full-profile fitting technique. Wide homogeneous ranges were observed in Y-S and Y-Se systems, and relatively narrow homogeneous ranges were observed in Yb-S and Yb-Se systems. Both in $Yb_{1-x}S\;and\;Yb_{1-x}Se$, a vacancy ordering transition occurred in (111) plane direction. The ordered superstructure had cubic symmetry(Fm$\bar{3}m) with doubled unit cell "a" parameter compared to the original NaCl-type. The superlattice developed in a continuous second-order transitiion was characterized by the reduced waved vector k= $(a^*+b^*+c^*)/2$. Y-S system had metallic, and YSe, YbSe system had semiconducting properties in their homogeneous ranges. It was observed that the change of electronic transport properties in extended homogeneous range did not depend on the relativeratio of metal to nonmetal, but on the quantities of vacancies.

• 한국자동차공학회논문집
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• 제24권2호
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• pp.242-254
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• 2016

This paper is the forth investigation on the evaluation methods of flow characteristics in a steady flow bench. In the previous works, it was concluded that the assumption of the solid rotation might cause serious problems and both of the eccentricity and the velocity profile distort the flow characteristics when using the ISM at 1.75B plane. Also particle image velocimetry (PIV) measurement at this position showed that the real velocity profile was far from the assumption of ISM evaluation. In this paper, the planar velocity profiles were measure from 1.75B to 6.00B position by PIV and the characteristics were examined according to the valve angles and lifts for further investigations about the effect of the position on the velocity profile. The results show that $26^{\circ}$ valve angle is always an unique exceptional case in all aspects. If the valve angle is $21^{\circ}$ and below, the planar velocity profiles according to the lift and the position are similar to each other, however, the tangential velocity curves along with the radial direction have common tendencies up to $16^{\circ}$ angle. Also the well arranged swirl behaviors are generally observed at the position above 3.00B and the velocity contour lines come closer to the concentric circle as the valve lift increases. In addition, the gradient of tangential velocity along with the radial direction from the swirl center becomes stable and constant as the position goes downstream. Concurrently the velocity gradient is larger to the eccentric direction of the center. In the meantime the tangential velocity curves along with the radial direction are irregular and various at 1.75B, however, they become regular and reach higher level as the evaluation position goes downstream. At this time the curves of 4.50B are the best fitted to the ideal one. On the other hand in an exceptional case, $26^{\circ}$, the velocity contours are very complicated over 6mm valve lift regardless the position and the gradient increases to the opposite direction of the eccentric center. Also, 6.00B is a best fitting position in the geometrical cylinder center base. With respect to the swirl center, the distribution range of centers for 1.75B is different to that for the other positions and the eccentricities of this plane are larger regardless the valve angle. After 1.75B, there is no certain tendency in the center position change according to the valve angle and lift. Additionally, the eccentricities are not sufficiently small to neglecting the effect on ISM measurement.

• Journal of Pharmaceutical Investigation
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• 제25권1호
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• pp.1-7
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• 1995

After oral administration of various drinking solutions, the initial absorption rate of water through gastrointestinal tract of the rabbits was evaluated using tritinated water $(^3H_2O)$ as a marker to develop the sports drinking beverage for Korean people. The polynomial curve fitting over 20 min was performed using computer program to obtain the initial absorption rate of water from the tangent line of the fitted equation because initial absorption rate of water was more critical compared to elimination rate during exercise. The amount of water absorbed was increased but a large variation was observed among testing preparations in a small study group $(2{\leq}n{\leq}6)$. The initial absorption rate of water from isotonic sports drinking beverages was statistically significant when compared to hypertonic cola but was not significant when compared to hypotonic solutions (potable water and barley water). In case of hypertonic sports dringking beverages (i.e. Takeda), initial absorption rate of water was not improved and efficient when compared to other isotonic sports dringking beverages. The initial absorption rate of water from prescribed isotonic sample solution containing electrolytes, carbohydrates, and vitamins was not statistically significant when compared to other isotonic drinking beverages but showed similar absorption profile. It was obvious that isotonic solutions simultaneously containing electrolytes, vitamins and carbohydrates (sugar and glucose) had a tendency to increase the initial absorption of water compared to hypotonic (potable water and barley water) and hypertonic preparations (orange juice and cola). Although statistical significance of initial absorption rate of water between isotonic sports drinking beverages and hypotonic potable and barley water was not observed, unlike the hypertonic solutions, isotonic sports drinking beverages may aid not only to replenish loss of water, electrolytes and other nutrients during the exercise but also to prevent dehydration and muscle fatigue, resulting in improved physical performance in an exhausted condition.