• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.11
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• pp.1862-1870
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• 1997

A fast and precise technique to measure 3-dimensional coordinates of an object is proposed. It is essential to take the 3-dimensional measurements of the object in design and inspection. Using this developed system a surface model of a complex shape can be constructed. 3-dimensional world coordinates are projected onto a camera plane by the perspective transformation, which plays an important role in this measurement system. According to the shape of the object two measuring methods are proposed. One is rotation of an object and the other is translation of measuring unit. Measuring speed depending on image processing time is obtained as 200 points per second. Measurement resolution i sexperimented by two parameters among others; the angle between the laser beam plane and the camera, and the distance between the camera and the object. As a result of these experiments, it was found that measurement resolution ranges from 0.3mm to 1.0mm. This constructed surface model could be used in manufacturing tools such as rapid prototyping machine.

• Journal of the Korean Society of Clothing and Textiles
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• v.30 no.11 s.158
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• pp.1598-1607
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• 2006

The purpose of this study was to analyze the proportion of gathered skirts using a three-dimensional measurement system. And in this experiment, we have attempted to accumulate three-dimensional data of wearing model and find out adequate methods for analyzing shape of clothes. The experimental design consists of two factorial designs. We established three different kinds of fabrics, ratio of gathers. The measurement tool for three-dimensional model was whole body 3D scanner(Exima-WBS2H). Analysis program used in experiment is RapidForm 2004 PP1 and Pattern Design 2000. Data analysis utilizes SPSS WIN 10.0 Package. As the results show, there were different effect of gather and proportion of shapes among the measurements of width, thickness and areas made by different lines of vision in cross-sectional silhouette. And there were difference shapes of section area at each part of gathered skirts between vertical-outline silhouette and vortical-plane silhouette made by gathering conditions. And also the cross-sectional silhouettes and vertical silhouettes were related to shape of clothes.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2005.11a
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• pp.64-71
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• 2005

To achieve efficient supersonic combustion within a manageable length, a successful fuel injection scheme must provide rapid mixing between fuel and airstream. In former days, various injection concepts have been investigated. Cavity flow is the open type, that is, length-to-depth ratio L/D=4.8, aft ramp angle is $22.5^{\circ}$. An experimental study on a transverse cross jet injection into a Mach 1.92 supersonic main stream which flows over a cavity was carried out to investigate the effect of the momentum flux ratio(J), the jet interaction characteristics, and the pressure distribution in the combustor and using the primary diagnostics : schlieren visualization and wall static pressure measurements. Fuel penetration height and jet interaction characteristics depend strongly on the momentum flux ratio.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.696-698
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• 2001

This paper considers the research of the hybrid interrupter which adopts both rotating arc and thermal expansion technology. The operating principle of this device depends on rapid arc rotation due to the magnetic field created by the fault current through a coil which is mounted on contacts and also relies on the principle of thermal expansion created by arc energy in extinguishing chamber and finally causes pressure rise in expansion volume. To develope this type of interrupter, we introduced analytical analysis including electromagnetic and arc fluid simulation and experimental analysis including construction of current source generation facility and arc behavior measurements. In this research, the principle of the interrupting techniques are given and analytical and experimental results of hybrid interrupter which is developed by new technology is introduced.

• Journal of the Korean Ceramic Society
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• v.31 no.7
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• pp.753-758
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• 1994

(100) Si and 4$^{\circ}$off (100) Si were oxidized in dry oxygen, and the differences in thermal oxidation behavior and electrical characteristics between two specimens were investigated. Ellipsometer measurements of the oxide thickness produced by oxidation in dry oxygen from 1000 to 120$0^{\circ}C$ showed that the oxidation rates of the 5$^{\circ}$ off (100) Si were more rapid than those of the (100) Si and the differences between them decreased as the oxidation temperature increased. The activation energies based on the parabolic rate constant, B for (100) and 4$^{\circ}$off (100) Si were 25.8, 28.6 kcal/mol and those on the linear rate constant, B/A were 56.8, 54.9 kcal/mol, respectively. Variation of C-V characteristics with the oxidation temperature showed that the flat band voltages were shifted positively and surface state charge densities decreased as the oxidation temperature increased, and the surface state charge density of the 4$^{\circ}$off (100) Si was lower than that of the (100) Si. Also considerable decrease in the density of oxidation induced stacking faults (OSF) for the 4$^{\circ}$off (100) Si was observed through optical microscopy after preferentially etching off the oxide layer.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.1576-1579
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• 2005

With varying rapid thermal annealing (RTA) temperature, luminescence properties of $Zn_{0.75}Mg_{0.25}S:Mn$ thin film deposited by RF-magnetron sputtering technique were investigated. In this study, $Zn_{0.75}Mg_{0.25}S:Mn$ thin film phosphor showed more red emission than those of the previous studies when annealed around 600 or $650^{\circ}C$. Although all samples were deposited from identical source composition, a main peak wavelength of photoluminescence spectra of $Zn_{0.75}Mg_{0.25}S:Mn$ shifted toward shorter wavelengths depending upon increase of RTA temperature. The same dependence of wavelength on RTA temperature was also observed in cathodoluminescence as well as electroluminescence measurements. It was revealed that the change of the luminescence properties were originated from structural changes in $Zn_{0.75}Mg_{0.25}S:Mn$ thin film phosphor from cubic to hexagonal phases analyze using conventional X-ray pole figure mapping. The phase transition would be the origin of luminescence property changes with respect to RTA temperature.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.5
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• pp.102-107
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• 1996

Use of a rapid thermal annealing (RTA) technique is shown to improve the properties of metal-ferroelectric BaMgF$_{4}$-silicon structures. The fluoride film was deposited in an ultra-high vacuum system at asubstrate temperature of 300$^{\circ}C$. A post-deposition annelaing was conducted for 10 seconds at 600.deg. C in a vacuum of 0.1 Torr, using a home-made RTA apparatus. The results showed that the resistivity of the ferroelectric BaMgF$_{4}$ film from a typical value of 1-2${\times}10^{11}{\Omega}{\cdot}cm$ before the annealing to about 5${\times}10^{13}{\Omega}{\cdot}cm$ and reduce the interface state density of the BaMgF$_{4}$/Si interface to about 8${\times}10^{10}cm^{2}{\cdot}$eV. Ferroelectric hysteresis measurements using a sawyer-tower circuit yielded remanent polarization and coercive field values of about 0.5$\mu$C/cm$^{2}$ and 80 kV/cm, respectively. the typical remanent polarization of the BaMgF$_{4}$ films ont he (100) and (111) oreientated silicon wafers were 0.5 - 0.6 $\mu$C/cm$^{2}$ and that of th efilms on the (110) wafers was 1.2$^{\circ}C$/cm$^{2}$.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.11 s.254
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• pp.1051-1056
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• 2006

The mean and RMS velocity field of the respiratory gas flow in the human airway was studied experimentally by particle image velocimetry (PIV). Some researchers investigated the airflow for the mouth breathing case both experimentally and numerically. But it is very rare to investigate the airflow of nose breathing in a whole airway due to its geometric complexity. We established the procedure to create a transparent rectangular box containing a model of the human airway for PIV measurement by combination of the RP and the curing of clear silicone. We extend this to make a whole airway including nasal cavities, larynx, trachea, and 2 generations of bronchi. The CBC algorithm with window offset (64 $\times$ 64 to 32 $\times$ 32) is used for vector searching in PIV analysis. The phase averaged mean and RMS velocity distributions in Sagittal and coronal planes are obtained for 7 phases in a respiratory period. Some physiologic conjectures are obtained. The main stream went through the backside of larynx and trachea in inspiration and the frontal side in expiration. There exist vortical motions in inspiration, but no prominent one in expiration.

• Journal of Preventive Medicine and Public Health
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• v.19 no.1 s.19
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• pp.76-84
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• 1986

Analyses of lead and zinc were made by means of standard addition method using atomic absorption spectrophotometer(Baird Ltd., Model A5100) with flameless method for lead and flame method for zinc. The blood samples used were merely diluted with triton x-100, because it was simple, rapid and minimal risk of contamination. Mean recovery rate for lead added to the blood ranged from 97.7 to 101.3% with coefficient of variation ranging from 1.9 to 10.7%, and that for the added zinc ranged from 99.0 to 102.2% with coefficient of variation ranging from 2.1 to 9.1%. In repeated measurements of zinc in the blood, good reproducibility and interindividual variation were proved(p<0.01). In comparison of the lead and zinc concentrations in the blood determined by the standard addition method and standard method, there were good correlations between 2 sets of data (r=0.9731 for lead and r=0.9785 for zinc), although lead levels were estimated higher by the former method(p<0.01) and zinc levels by the latter method(p<0.01). It can be concluded that lead and zinc levels in blood standard addition method is reliable for determination of lead and zinc in the blood with good accuracy and reproducibility.

• Transactions of the Korean Society of Mechanical Engineers
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• v.9 no.4
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• pp.403-413
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• 1985

Hot-wire measurements of second and third-order mean products of velocity fluctuations have been made in the separated, reattached, and redeveloping boundary layer behind a vertical fence. Mean velocity, wall static pressure distributions have also been measured in the whole flow field. Upstream of the reattachment point, the separated shear layer developes as a free mixing layer, but the gradient of the maximum slope thickness, turbulent intensities and the Reynolds shear stress are higher than that of the mixing layer due to initial streamline curvature and the effects of highly turbulent recirculating flow region. In the reattachment region, Reynolds shear stress and triple products near the surface is far more rapid than the decrease of the shear stress; that is the presence of the solid wall has a marked effect on the apparent gradient diffusivity of intensity or shear stress and throws doubts upon the usefulness of the simple gradient diffusivity model in this region.