• Journal of the Korea Institute of Military Science and Technology
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• v.8 no.3 s.22
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• pp.64-72
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• 2005

In this paper, we propose a design method of the millimeter-wave(W-Band) waveguide cavity harmonic voltage controlled oscillator(VCO) using a Gunn diode for the armor sensor. Using the 3-dimensional simulation tool(Ansoft $HFSS^{TM}$), we were able to find the impedance matching point between waveguide and Gunn diode and estimate the oscillation frequency. A varactor diode is used for the frequency tuning, and we find out the equation for the calculation of the tunable frequency range. The designed VCO shows good performances; 17dBm output power at 94GHz center frequency, 520MHz frequency tuning range similar to the estimated value(480MHz).

• The Transactions of the Korean Institute of Electrical Engineers
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• v.40 no.12
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• pp.1211-1217
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• 1991

A three dimensional magnetostatic probodm is analyzed using the boundary element method and the magnetic scalar potential are employed in order to reduce the size of system matrix. Although the total magnetic scalar potential gives very accurate solutions at inner and outer regions of magnetic materal, the method has limitation on application because the magnetic scalar potential due to applied magnetic field sources is hard to be obtained. The reduced magnetic scalar potential gives more or less inaccurate solutions inside the magnetic material but very accurate solutions outside. Hence it can be concluded that the reduced magnetic scalar potential is very useful when the magnetic fields of outside of magnetic fields of outside of magnetic material are interested. It is also shown, from the numerical example, that the linear shape function gives more efficient solutions than the constant shape functions.

• Proceedings of the KIEE Conference
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• summer
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• pp.1058-1060
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• 2004

This paper presents a characteristic analysis method for an air gap flux density of axial-flux type brushless dc (BLDC) motor. The magnetic flux density for the torque, and vertical force characteristics is calculated by using analytical method, based on the concept of magnetic charge. The calculated results by the presented method is compared with those by 3 dimensional finite element method (3D FEM). Using the presented method, the characteristics of single and double sided axial-flux type BLDC motors are investigated through distributions of air gap flux density.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.2265-2267
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• 2005

We present detailed studies of externally applicable UHF PD sensors for a metal covered epoxy barrier with a small opening of epoxy injection-hole. The sensors were attached at the surface of injection hole of a metal covered epoxy barrier. 3-Dimensional electro magnetic simulations were performed to analyze electric-field distribution of the GIS and epoxy barrier with injection hole. Sensor structures were designed and analyzed using the 3-D EM simulator then fabricated for experimental verification. Sensor performance was measured in terms of spectral response and detected peak power. Real scale GIS and epoxy barriers were used to test and measure various aspect of performance of the sensors.

• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.894-896
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• 2003

This paper present the design algorithm using torque and rotor volume(TRV). And, this paper introduce that how to applying the 3-Dimensional Equivalent Magnetic Circuit Network(3D EMCN) and brushless motor circuit simulator. This algorithm is applied the design program, the design shape is compared with existed brushless motor.

• Journal of Powder Materials
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• v.8 no.1
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• pp.20-25
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• 2001

Most of mold manufacturing procedures have been automated by the introduction of NC machine tool and CAD/CAM system. But the three-dimensional surface curvature of the mold must be done by hand work of well-skilled workers. Magnetic abrasive polishing powders were investigated for surface polishing for 3D curvature. This study aims to investigate homogeneously distributed hard phase in Fe matrix and strong bonding between Fe-matrix and hard phase. The NbC powder, $B_4C$ powder and $Al_2O_3$ powder were mixed in Fe-matrix respectively. Mixed Fe-hard phase powders were compacted by press and then these were melted by plasma melting. According to SEM, XRD and OM observation, Fe-NbC magnetic abrsive powder had the most homogeneous distribution and strong bonding. As a result of magnetic polishing, the surface roughness before magnetic polishing, 1 ${\mu}m$ $R_{max}$, was reduced to 0.2 ${\mu}m$ $R_{max}$ over the entire inner surface of the tube.

• Proceedings of the KIEE Conference
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• 2007.11a
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• pp.163-164
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• 2007

In this study, we developed intelligent spacer built in the internal type UHF PD sensors. 3-Dimensional electro-magnetic simulations were performed to analyze electric-field distribution of the single-phase GIS and three-phase GIS. After considering the spacer's specification, Sensor structures were designed and analyzed using the 3-D EM Simulator. As a result of the simulation the internal type UHF PD sensors were built in. Performance of the sensor built into real scale GIS spacer was measured in terms of return loss and detected Max voltage. And we identified a character of the intelligent spacer by using 5pC partial discharge ceil.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.1
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• pp.107-113
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• 2017

Unlike regular images, there is no ground truth for bio surface images. Result of biosurface imaging is not only significantly affected by the environment and the condition of the bio surface, it requires more detailed expression than regular images. Therefore, unlike algorithms tested on regular images, studies on bio surface images requires a highly precise optimization process. We aim to optimize the graph cut algorithm, known to be the most outstanding among the stereo visions, by considering baseline, lambda, and disparity range. Optimal results were in the range of 1~10 for lambda. The disparity ranged from -30 to -50, indicating an optimal value in a slightly higher range. Furthermore, we verified the tested optimization data using SIFT.

• Nuclear Engineering and Technology
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• v.29 no.1
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• pp.58-67
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• 1997

A numerical study has been peformed to investigate the flow and mixing characteristics of a chemical injection tank in the chemical and volume control system (CVCS) of Yonggwang 5&6 (YGN 5&6). This study was undertaken to provide a basis for modification of the previous design (YGN 3&4) which gave a lot of difficulties in installation and operation of the chemical injection system during the start-up test because it needs a special reciprocating pump with a high actual head. For the tank of length-to-diameter ratios (L/D) of 1,2 and 3, each with and without a baffle inside, calculation results were obtained by solving the unsteady laminar two-dimensional elliptic forms of governing equations for the mass, momentum and species concentration. Finite-difference method was used to obtain discretized equations, and the SIMPLER solution algorithm, which was developed based on the staggered grid control volume, was employed for the calculation procedure. Results showed that the baffle is very effective in enhancing the mixing in the tank and that a baffle should be installed near the tank entrance in order to 110 chemicals into the reactor coolant system (RCS) within the operating time required.

• 한국가시화정보학회:학술대회논문집
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• 2002.11a
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• pp.11-14
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• 2002

A new high-definition stereoscopic PTV was constructed using two CCD cameras, stereoscopic photogrammetry based on a 30-PTV principle. The arrangement of the two cameras was based on angular position. The calibration of cameras and the pair-matching of the three-dimensional velocity vectors were based on Genetic Algorithm based 30-PTV technique. The constructed Stereoscopic PTV technique was tested on the standard images of the Impinging jet proposed by VSJ. The results on the turbulent properties of the jet obtained by the constructed system showed a good agreement with the original LES data.