• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.13 no.2
• /
• pp.208-216
• /
• 2002

In this paper, the design method of a waveguide broad-wall longitudinal slot array monopulse antenna of X-type monopulse axes is presented, and the method is verified through manufacture and measurement. In the antenna design of this paper, the antenna size is small and the monopulse axes are X-type. Thus, the common continuous aperture distribution fuction is not suitable and the power balance among antenna quadrants should be considered. Also, since the waveguide height is reduced into 0.1 wavelength, the modelling of the slot characteristics is not simple. Thus, in this paper, the aperture distribution is optimized by using random number, and the balance among the quadrants is achieved by applying the quadrant weighting factor during the aperture optimization process. Also, the moment method procedure is accelerated by applying the interpolation technique to some part of the moment matrix, and the moment method procedure is added to the array synthesis program as a subroutine so that the slot characteristics can be calculated directly when it is required. Based on this method, a antenna of 28dBi is designed and manufactured. It is found that the antenna characteristics is similar to design data.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2016.10a
• /
• pp.61-62
• /
• 2016

In this paper, a design method for a compact stepped open slot antenna for an operation in the UWB band is studied. The proposed antenna is miniaturized by inserting L-shaped slots on the ground plane of the stepped open slot antenna through the creation of a resonance in the low frequency, and a strip director is appended to the antenna in order to increase the gain in the middle and high frequency regions. The effects of varying the length of the L-shaped slots, the distance between the director and the slot antenna, and the director length on input reflection coefficient and realized gain characteristics of the proposed antenna are analyzed. The optimized antenna with the size of $30mm{\times}30mm$ is fabricated on an FR4 substrate, and the experiment results show that the antenna has a frequency band of 3.02-11.04 GHz for a VSWR < 2, which assures the operation in the UWB band.

• 한국전산유체공학회:학술대회논문집
• /
• 2010.05a
• /
• pp.187-194
• /
• 2010

Shape optimization of an upper plenum of PBMR type gas cooled nuclear reactor has been performed by using three-dimensional Reynolds-Averaged Navier-Stokes (RANS) analysis and surrogate modeling technique. The objective function is defined as a linear combination of uniformity of flow distribution in the core and pressure drop in the upper plenum and the core. The ratio of thickness of slot to diameter of rising channels, ratio of height of upper plenum to diameter of rising channels, and ratio of eight of the slot at inlet to outlet, are used as design variables for optimization. Design points are selected through Latin-hypercube sampling. The optimal point is determined through surrogate-based optimization method which uses 3-D RANS analyses at design points. The results show that the optimum shape represent remarkably improved performance in flow uniformity and friction loss than the reference shape.

• Journal of computational fluids engineering
• /
• v.15 no.3
• /
• pp.16-23
• /
• 2010

Shape optimization of an upper plenum of a PBMR type gas cooled nuclear reactor has been performed by using three-dimensional Reynolds-Averaged Navier-Stokes (RANS) analysis and surrogate modeling technique. The objective function is defined as a linear combination of uniformity of flow distribution in the core and pressure drop in the upper plenum and the core. The ratio of thickness of slot to diameter of rising channels, ratio of height of upper plenum to diameter of rising channels, and ratio of height of the slot at inlet to outlet, are used as design variables for optimization. Design points are selected through Latin-hypercube sampling. The optimal point is determined through surrogate-based optimization method which uses 3-D RANS analyses at design points. The results show that the optimum shape represent remarkably improved performance in flow uniformity and friction loss than the reference shape.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.14 no.1
• /
• pp.55-60
• /
• 2019

Because of an rapid increase of using a wireless Internet, the originally used communication of 2.4 GHz band was saturated and crossed and there were some problems. According to this, the development of a wireless Internet technology of 5 GHz Band proceeded. In the thesis we researched a Square Slot Microstrip Patch Antenna available in 5 GHz band of wireless communication. The research designed and analyzed the Antenna through HFSS. Ultimately, we compared and analyzed made Antenna through a Network Analyzer.

• 한국전산유체공학회:학술대회논문집
• /
• 2003.10a
• /
• pp.91-92
• /
• 2003

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.4
• /
• pp.683-688
• /
• 2018

Recently, the demand for electric energy has been increasing due to the spread of hybrid electric vehicles. In this study, to meet this demand, the ANSYS MAXWELL electromagnetic simulation system was used to compare the power generation characteristics of three types of suspension system that can generate electricity using energy harvesting technology. Next, the optimal design was determined for each model by using the commercial PIDO (Process Integration and Design Optimization) tool, PIANO (Process Integration, Automation and Optimization). We selected three design variables and constructed an approximate model based on the experimental design method through electromagnetic analysis for 18 experimental points derived from Orthogonal Arrays among the experimental design methods. Then, we determined the optimal design by applying the Evolutionary Algorithm. Finally, the optimal design results were verified by electromagnetic simulation of the optimum design result model using the same analysis conditions as those of the initial model. After comparing the power generation characteristics for the optimal structure for each linear generator model, the maximum power generation amounts in the 8pole-8slot, 12pole-12slot, and 16pole-16slot structures were 366.5W, 466.7W and 579.7W, respectively, and it was found that as the number of slots and poles increases, the power generation increases.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.16 no.1
• /
• pp.31-40
• /
• 1992

This paper presents an automatic feature recognition system for recognizing and extracting feature information needed for the process planning input from a 3D CAD system. A given part is modeled by using the AutoCAD and feature information is automatically extracted from the AutoCAD database. The type of parts considered in this study is prismatic parts composed of faces perpendicular to the X, Y, Z axes and the types of features recognized by the proposed system are through steps, blind steps, through slots, blind slots, and pockets. Features are recognized by using the concept of convex points and concave points. Case studies are implemented to evaluate feasibilities of the function of the proposed system. The developed system is programmed by using Turbo Pascal on the IBM PC/AT on which the AutoCAD and the proposed system are implemented.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.21 no.8
• /
• pp.1517-1530
• /
• 2017

Traditional anti-collision algorithms determine slot size of initial frame based on the information of number of collision slots, idle slots, and success slots. Since there is no information about collision at the beginning of tag information collection, traditional anti-collision algorithms can not determine the initial frame size. Considering that performance of anti-collision algorithm is very sensitive to initial slot size traditional anti-collision algorithms need some improvements. In this study two methods are proposed to determine slot size of initial frame efficiently, through which we can improve the performance of dynamic frame slotted aloha algorithm. To verify the performance of proposed algorithms, 2.4GHz RFID system is used. Throughput and delay time are derived through simulation, which is developed using JAVA. We have seen that proposed algorithm improves throughput by 9.6% and delay time by 9.8%.

• Transactions of Materials Processing
• /
• v.18 no.2
• /
• pp.156-159
• /
• 2009

Slot coating has been wide spread in photo-resist coating on the glass for liquid crystal display. Die in slot coater consists of manifold and land. Material comes in inlet of the die and flow into the manifold and then flow out through the land. The coating thickness variations along the die length depend upon inside of die design such as manifold and die land. However the coating thickness variations along the moving direction(coating direction) of the coater depend upon the operational conditions of coater as well as die lip design. The coating behaviors including atmospheric air have been investigated in this study. Die geometries considered in this study were nozzle gap and length of the die lip. Coating gap and coating speed were the variables fur coating operational conditions. When the nozzle gap and length of die lip increased climbing effect of PR on the downstream die lip was reduced. Subsequently uniformity of coating thickness improved. Uniformity of coating thickness also enhanced as coating gap and coater speed increased. The uniformity of coating gap was related to the velocity vector distributions on the coating surface.