• Journal of the Korean Society of Propulsion Engineers
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• v.16 no.2
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• pp.10-16
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• 2012

A computational analysis of nozzle flow characteristics and plume structure is conducted to examine performance of the supersonic nozzle employed in a thruster for ground firing test. At first, flow simulations in two-dimensional converging-diverging nozzle are performed for the verification of computational capability as well as turbulence model validity. Axisymmetric converging-diverging nozzles for ground firing test are analyzed with the k-${\omega}$ SST model. A performance penalty caused by flow separation in a diverging section is observed in initially-designed nozzle. The performance could be enhanced by the modification of the diverging section of nozzle contour.

• The Journal of Korea Assosiation for Disability and Oral Health
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• v.3 no.2
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• pp.87-90
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• 2007

It's important that detect early caries of deciduous and permanent teeth to prevent dental caries and prevserve teeth, especially on proximal surface of deciduous teeth. The reason is that their prominent pulp horn lead to pulp treatment easily due to rapid caries progression. There are conventional exploring, visual inspection and radiographic exam for early caries detection. But, the standard method for diagnosing dental caries is subject and cavitation may be accelerated during exploring procedure. Caries can be diagnosed up to 40% mineral loss with radiograph. $DIFOTI^{(R)}$ (Digital Imaging Fiber-Optic TransIllumination) is diagnostic imaging system for early caries detection using fiber-optic illumination. It is possible that remineralize the tooth surface without tooth preparation and conserve the tooth structure by using $DIFOTI^{(R)}$.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.439-442
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• 2005

An airborne radar performance can be sensitive to the variation of the Doppler center frequency and the spectral spread of the ground clutter return due to the radar platform moving and aspect angle of the scanning beam to the target. In this paper, for the performance test of the airborne pulsed Doppler radar system developed, the high-speed radar data acquisition system is implemented for acquiring the raw radar signal in real-time. Based on the various test scenarios from airborne-platform to the moving platform, the various radar target and clutter signals are collected and their spectrum is analyzed for the verification of the radar performance in the real-time flight test environments.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.443-446
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• 2005

This paper presents the results of the design and implementation of the airborne pulse doppler radar signal processor using high multi-DSP for the multi-function radar capability such as short-range, midium-range, and long-range depending on the mission of the vehicle. Particularly, the radar signal processor is developed using two DSP boards in parallel for the various radar signal processing algorithm. The key algorithms include LFM chirp waveform-based pulse compression, MTI clutter filter, MTD processor, adaptive CFAR, and clutter map. Especially airborne moving clutter Doppler spectrum compensation algorithm such as TACCAR is implemented for the multi-mode airborne radar system. The test results shows the good Doppler spectral separation for the clutter and the moving target in the flight test environment using helicopter

• Journal of the Korean Chemical Society
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• v.31 no.2
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• pp.178-183
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• 1987

The kinetics of the reaction of $[Mo_3O_4(H_2O)_9]^{4+}$ with $VO_2^+$have been studied at $25^{\circ}C$ by spectrophotometric method. With$VO_2^+$ in excess, the $[Mo_3O_4(H_2O)_9]^{4+}$ reaction can be expressed as $Mo^{IV}_3+6V^V{\rightleftarrows}3Mo^{IV}+6V^IV}$. Observed rate constants for the reaction are dependent on [$H^+$] and [$VO_2^+$]. Mechanism for the redox of $[Mo_3O_4(H_2O)_9]^{4+}$and $VO_2^+$ is proposed and discussed.

• Proceedings of the Korea Contents Association Conference
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• 2006.11a
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• pp.599-603
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• 2006

Korea Information Security Agency has executed the certification system for the information security management since 2002 and examines the conformance of the IDCs'total management system including the technical and the physical protection measure. However, this certification system has the standard only for the IDC in the wire/wireless segregated and the evaluation method for the wire/wireless integrated has not been suggested yet. This paper is on the basis of "Accumulation Information Communication Facility Secure Principle", guidelines of Wireless LAN security operation, the existing principles and recommendations of the information security and the data on IDC environment. And the paper suggests the IDC network model in the wire/wireless integrated and the IDC evaluation method.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.1
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• pp.262-273
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• 1991

In the present study, the steady, incompressible, isothermal, developing flow in a 90.deg. rectangular cross sectional strongly curved duct with aspect ratio 1:1.5 and Reynolds number of 9.4*10$^{4}$ has been investigated. Measurements of components of mean velocities, pressures, and corresponding components of the Reynolds stress tensor are obtained with a hot-wire anemometer and pitot tube. In general, flow in a curved duct is characterized by the secondary vortices which are driven mainly by centrifugal force-radial pressure gradient imbalance, and the stress field stabilizing effects near the convex wall and destablizing effects close to the concave wall. It was found that the secondary mean velocities attain values up to 39% of the bulk velocity and are largely responsible for the convections of Reynolds stress in the cross stream plane. Therefor upstream of the bend the Reynolds stress are low. Corresponding to the small boundary layer thickness. At successive planes, large values of Reynolds stress were observed near the concave surface and the side wall.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.1
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• pp.274-284
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• 1991

Mean flows and Reynolds stresses through circular and elliptic wire-mesh screens in the wind tunnel are measured by using the hot-wire system, and flow structures are investigated. Flow in the core of the wake are nearly uniform and the shear layer is developed along the edge of the screen The turbulent kinetic energy in the core decreases at the fast rate. However turbulence components are not in local equilibrium in the shear layer. The shear layer of the circular screen develops outward according to the radial mean motion. On the other hand, 3-dimensional transverse mean motion was turned to the main mechanism for the elliptic shape of the wake to be circular at the downstream.

• Koreanishche Zeitschrift fur Deutsche Sprachwissenschaft
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• v.2
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• pp.343-370
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• 2000

Im Rahmen der Prinzipien- und Parametertheorie (PPT) stellt man sich vor, $da\ss$ dem Menschen die Universalgrammatik (UG) angeboren ist, die aus einer kleinen Anzahl sprachuniversieller Prinzipien und je nach der Sprache unterschiedlich zu belegender offener Parameter besteht. Die UG Prinzipien $m\"{u}ssen$ demnach nicht gelemt werden; sie bilden von vomherein eine invariante Komponente des sprachlichen Wissens. $Demgegen\"{u}ber$ sollen die jeweilige Parameter der UG im Verlauf des Spracherwerbs aufgrund des sprachlichen Inputs mit Werten der Zielsprache belegt werden. Nach dieser Ansicht ist der Spracherwerb im Grunde als $Proze{\ss}$ der 'Parameterbelegungen' aufzufassen. In der vorliegenden Arbeit ist demonstriert worden, $da{\ss}$ die PPT eine vielversprechende Grundlage fur die empirische Untersuchung zum Erwerb des Deutschen bietet. Bisherige Ergebnisse aus Untersuchungen zum Erwerb der Reflexiv-Bindung beim Erst- sowie Zweitspracherwerb wurden vorgestellt und im Hinblick auf die $M\"{o}glichkeit$ der weiteren Untersuchung zum Zweitspracherwerb des Deutschen durch Koreaner diskutiert. Der Schwerpunkt der Diskussion wurde auf die Frage gelegt, wie die Theorie des Parameters mit Ergebnissen aus Untersuchungen zur Parameterbelegung beim Spracherwerb interagiert. Auf psychologisch bzw. kognitionswissenschaftlich orientierte $Ans\"{a}tze$ zum Spracherwerb konnte in der vorliegenden Arbeit nicht eingagangen werden. Durch die $Mitber\"{u}cksichtigung\;beider\;Ans\"{a}tze\;w\"{u}rde$ jedoch das Thema 'der Erwerb des Deutschen' die Angewandte Deutsche Sprachwissenschaft in Korea noch mehr anreichern.

• Journal of the Society of Naval Architects of Korea
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• v.44 no.2 s.152
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• pp.139-147
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• 2007

The ultimate goal of structural design is to find the optimal design results which satisfies both safety and economy at the same time. Optimum design has been studied for the last several decades and is being studied. in this study, an optimum algorithm which is based on the genetic algorithm has been applied to the multi-object problem to obtain the optimum solutions which minimizes structural weight and construction cost of panel blocks in ship structures at the same time. Mathematical problems are dealt at first to justify the reliability of the present optimum algorithm. And then the present method has been applied to the panel block model which can be found in ship structures. From the present findings it has been seen that the present optimum algorithm can reasonably give the optimum design results.