• Proceedings of the Korean Nuclear Society Conference
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• 2002.05a
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• pp.142.2-142
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• 2002

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2006.07a
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• pp.706-706
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• 2006

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2006.07a
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• pp.697-697
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• 2006

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2006.07a
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• pp.711-711
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• 2006

• Journal of the Korean Institute of Telematics and Electronics A
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• v.30A no.2
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• pp.22-28
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• 1993

In this paper, the ultrasonic transducer with a spherical liquid lens is designed and an efficient method to calculate the acoustic field radiated from the transducer is presented. A prototype ultrasonic transducer with a spherical liquid lens is constructed and tested. The experimental results are compared with those of the computer simulations and good agreements are achieved. The dynamic control of the geometric focus is obtained by adjusting the radius of curvature of the lens membrane with the volumetric control of the liquid in the lens.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.7 no.4
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• pp.328-335
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• 1996

The numerical dispersive characteristics and the numerical stability confition of the Multi-Resolution Time-Domain(MRTD) method are calculated. A dispersion analysis of the MRTD schemes including a comparison to Yee's Finite-Difference Time-Domain(FDTD) method is given. The superiority of the MRTD method to the spatial discretization is shown. The required computational memory can be reduced by using the MRTD method. We expect that the MRTD method will be very useful method for numerical modelling of electromagnetics.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2002.11a
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• pp.398-401
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• 2002

본 논문은 최근 사용이 증가하고 있는 1㎓ 이상 장해파의 허용 기준안을 정하기 위한 측정에 이용되는 피시험체의 최적 회전 스텝 크기를 결정하고 방사 패턴의 측정 및 결과를 나타내었으며 기가헤르츠 대역의 CISPR 허용기준치와 비교하였다. 실제 피시험체를 측정한 결과, 가장 좁은 3㏈ 빔폭은 수평편파에서 약 18도, 수직편파에 대해 약 20도 정도이다. 최대 방사 방향에서 3㏈ 빔폭의 경우 수평편파에서는 60도이며 수직 편파에 대해서는 50도를 보였고, 적절한 스텝 크기는 40개였다. 또한 CISPR에서 제안한 허용기준치에 측정값이 만족하는 것을 알 수 있었다.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2004.11a
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• pp.411-411
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• 2004

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.11
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• pp.9-16
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• 1995

In this paper, an ultrasonic phased array transducer with spherical liquid lens, which utilizes both electronic focusing by linear phased array and variable geometric focusing by spherical lens. is investigated. This system reduces the elevational beamwidth which is disadvantage of the 1-dimensional linear phased array, and adds real-time dynamic focusing capability by controlling the volume of liquid in the lens. A prototype of this transducer is constructed and tested. The experimental results are compared with those of computer simulations. The range of applications are in the hyperthermia applicators or ultrasonic image system with narrow beam and rapid scanning characterisitcs.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.7
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• pp.677-684
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• 2004

This paper presents direct T $M_{01}$-T $E_{11}$ small mode converter using circular waveguide with tilted structure for X-band high power system. It is designed to transmit microwave energy from Relativistic Backward-Wave Oscillator(RBWO) source to hem antenna effectively, with optimized geometry a parameter study The simulated and measured results of return loss, fractional power of each mode, impedance bandwidth and mode pattern are provided.d.