• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.11
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• pp.1774-1784
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• 1993

This paper presents the design, fabrication and measured results of the broadband microstrip array with a conical radiation pattern and the circular array composed of six square microstrip antenna elements. Each element antenna has the stacked structure with a parasitic element to achieve a broadband characteristic and a branch line quadrature hybrid is attached to it for the circular polarization. The design procedures and measured results of the scheme for obtaining the conical radiation pattern which is useful for the mobile communication via the satellite. Finally, the performance of the fabricated antenna is measured and compared with the theory.

• Journal of Dental Rehabilitation and Applied Science
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• v.36 no.2
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• pp.95-103
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• 2020

Purpose: The purpose of this study was to compare the axial displacement of the hexagonal and conical abutment in internal conical connection implant after screw tightening and cyclic loading. Materials and Methods: Internal conical connection implants were divided into two groups (n = 10): group HEX, hexagonal abutment; and group CON, conical 2-piece abutments. The axial displacement and removal torque values were measured after 30 Ncm torque tightening and 250N loading test of 100,000 cycles. The Student t test with 5% significance level was used to evaluate the data. Results: HEX group demonstrated significantly higher axial displacement values after 30 Ncm tightening in comparison to the CON group (P < 0.05). No significant difference was found in axial displacement after cyclic loading (P = 0.052). Removal torque loss before and after the cyclic loading both revealed no significant difference between groups (P = 0.057 and P = 0.138). Removal torque value decreased after cyclic loading in both groups (P < 0.05). Conclusion: Overall, both abutment with or without hexagon index presented similar biomechanical performance except HEX group demonstrated significantly more axial displacement after applying tightening torque.

• Proceedings of the IEEK Conference
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• 2000.09a
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• pp.763-766
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• 2000

본 논문에서는 해저 고정형 선배열센서를 이용하여 다중경로 신호를 이용한 근거리표적의 위치 추정 알고리즘을 제안하였다. 다중경로를 통하여 근거리 표적의 신호가 센서에 도달하는 경우 각 신호의 원추각이 다르므로 신호들의 원추각과 시간차를 추정해서 3차원 표적의 위치를 추정할 수 있다. 원거리표적으로 가정하고 추정한 원추각과 신호들의 시간차에 대한 관계식을 유도하였으며 이들을 연립하여 표적의 위치를 추정하였다. 그러나 표적이 위치한 기하학적인 위치에 따라 신호들의 원추각이 거의 같아지는 지점이 존재한다. 이 경우 부가적인 1차원 탐색으로 표적의 위치를 추정하였다.

• Journal of Technologic Dentistry
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• v.27 no.1
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• pp.193-198
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• 2005

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.2
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• pp.101-107
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• 2016

This paper presents the characteristics of a double-cone broadband antenna with compact and three-dimensional structure that can be used in UWB system. The theoretical analysis is conducted using a finite difference time domain(FDTD) method. The parameters are the radius, a height of broadband double-cone antennas with shorting plate, and the number of plates on a ground plane. This paper examines influence of structural parameters on return loss. The results show that a condition for an optimum structure of broadband double-cone antennas with shorting plate exists. It also shows that the broadband double-cone antennas with shorting plate have radiation patterns similar to those of a dipole antenna. To verify the theoretical analysis, computed results are compared to experimental results.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.04a
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• pp.196-199
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• 2011

Subscale high-pressure injection system which use two-stage light gas gun composed with high-pressure tube, pump tube and launch tube can make supersonic liquid jet. The supersonic liquid jet enhances droplet atomization by shockwave in front of the jet. In this study, the experiments was executed to identify the atomization characteristics of the supersonic liquid jet using straight cone nozzle. SMD which presents the atomization characteristics was decreased from $151.2{\mu}m$ to $52.25{\mu}m$ by increasing of L/d.

• Journal of Power System Engineering
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• v.12 no.2
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• pp.35-40
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• 2008

This paper deals with the free vibrations of conical shells with linearly variable thickness by the transfer influence coefficient method. The classical thin shell theory based upon the Flugge theory is assumed and the governing equations of a conical shell are written as a coupled set of first order matrix differential equations using the transfer matrix. The Runge-Kutta-Gill integration method is used to solve the governing differential equation. The natural frequencies and corresponding mode shapes are calculated numerically for the conical shells with linearly variable thickness and various boundary conditions at the edges. The present method is applied to conical shells with linearly varying thickness, and the effects of the semi-vertex angle, the number of circumferential waves and thickness ratio on vibration are studied.

• Proceedings of the KSME Conference
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• 2001.06e
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• pp.499-505
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• 2001

The objective of the paper was to measure the pressure drop and to investigate the recirculation region of the conical orifices used in Kwang-yang Iron & Steel Company. The flow field with water used as a working fluid was the turbulent flow for Reynolds number of $2{\times}10^4$. The effective parameters for the pressure drop and the recirculation region were the conical orifice's inclined angle (${\theta}$) against the wall, the interval(L) between orifices, the relative angle of rotation(${\alpha}$) of the orifices, the shape of the orifice's hole(circle, rectangle, triangle) having the same area. It was found that the shape of the orifice's hole affected the pressure drop and the flow field a lot, But the other parameters did not make much differences to the pressure drop. The PISO algorithm with FLUENT code was employed.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.12
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• pp.3073-3082
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• 1993

A magnetically suspended robot joint is developed, which is free of dust and oil generation. Two radial bearings consisting of cone-shaped magnet cores control the rotor motion in the axial and radial directions. A linearized dynamic model is developed for active control of the magnetic bearing system. The control algorithm is constructed such that the axial displacement of the joint is controlled by radial control current to the pairs of facing radial bearings. The stability and control performance is tested through numerical simulation based on the nonlinear model. Experiments are also performed to verify the theoretical development.

• Journal of ILASS-Korea
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• v.2 no.1
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• pp.8-17
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• 1997

A study has been carried out on the instability of a conical liquid sheet by using the linear instability theory. Various analytical methods using the Kelvin-Helmholtz instability theory were tried to examine the wave growth on cylindrical liquid sheets. Cylinderical liquid sheets were extended to the case with the conical sheets. Perturbations due to tangential motion as well as longitudinal one were taken into account. And it was assumed the the breakup occurs when amplitude ratio exceeds exp(12), drop sizes were predicted only by theoretical approach. The predicted drop size agreed well with the measured Sauter mean diameter, $D_{32}$.