• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.5 s.120
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• pp.511-521
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• 2007

In this paper, we designed and fabricated a Ka-band synthesizer module. In addition, the systematic layout procedure and the test procedure were presented for the construction of compact synthesizer. To implement the Ka-band synthesizer, X-band VCO is employed as VCO and its frequency was multiplied by 3 with frequency tripler. The fabricated frequency synthesizer shows a frequency tuning range of 500 MHz, output power of about 14 dBm, and a phase noise of -96.17 dBc/Hz at the 100 kHz offset frequency.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.2
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• pp.207-213
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• 2013

This study describes an omega-K algorithm for focusing bistatic synthetic aperture radar(SAR) data using bistatic-to-monostatic conversion. Bistatic SAR system considered in this study consists of a transmitting antenna and a physical array of several receiving antennas. The length of the physical array is identical to the SAR synthetic aperture. Unlike the monostatic case, an omega-K algorithm for the bistatic case is difficult to obtain the exact equation in the 2D wavenumber domain. The key of the proposed algorithm is converting the bistatic data into a monostatic one. The effectiveness of the proposed algorithm is proved by simulation and real measurement data.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.8
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• pp.717-724
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• 2016

This paper presents design of a 40 GHz CMOS PLL frequency synthesizer for a 60 GHz sliding-IF RF transceiver. For stable locking over a wide bandwith for a injection-locked frequency divider, an inductive-peaking technique is employed so that it ensures the PLL can safely lock across the very wide tuning range of the VCO. Also, Injection-locked type LC-buffer with low-phase noise and low-power consumption is added in between the VCO and ILFD so that it can block any undesirable interaction and performance degradation between VCO and ILFD. The PLL is designed in 65 nm CMOS precess. It covers from 37.9 to 45.3 GHz of the output frequency. and its power consumption is 74 mA from 1.2 V power supply.

• Aerospace Engineering and Technology
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• v.6 no.1
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• pp.173-181
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• 2007

Radiated emission / susceptibility performance of the KSLV-I 2nd stage which are controlled from the unit level to the system level should be examined and managed all over the frequency ranges in order to ensure the normal operation of the SC, the 1st stage of the KSLV-I, ground support equipments which are installed at the space center, and other wireless communication networks. Not only unintentional electric field emissions from the KSLV-I system and its subsystems should be restricted to the levels less than the limits specified in the EMC requirements, but also proper test and evaluation method should be established, respectively. In this paper, radiated emission/susceptibility test limits, method, and test results of the KSLV-I 2nd stage engineering model are presented.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.7
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• pp.649-656
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• 2002

This paper addresses the phase noise analysis of high-speed DH-PLL(Digital Hybrid Phase-Locked Loops) frequency synthesizer. Because of the additional quantization noise of D/A converter in DH-PLL, the phase noise of DH-PLL is increased than the conventional PLL. Three kinds of noise sources such as reference input, D/A converter, and VCO(Voltage Controlled Oscillator) are considered to analyze the phase noise. It largely depends on the closed loop bandwidth and frequency synthesis division ratio(N) so that we can decide the optimal closed loop bandwidth to minimize the phase noise of DH-PLL. It is shown that the simulation results closely match with the results of analytical approach.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.8
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• pp.758-764
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• 2015

This paper describes the pattern synthesis of array antenna which conforms to a metallic curved surface formed by the rotation of a quadratic function by using EAGA(Enhanced Adaptive Genetic Algorithm). Three rotated-type conformal surfaces are realized by changing the coefficient of the quadratic function and the pattern of each conformal array antenna is synthesized. In order to reduce the overall time of pattern synthesis, the transformed active element pattern obtained by the active element pattern of the 2-dimensional planar array using Euler angles rotation is utilized instead of the active element pattern of the 3-dimensional conformal array antenna itself. To verify validity of the proposed synthesis procedure, the synthesized patterns using EAGA are compared with those obtained by MWS.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.11
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• pp.5442-5446
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• 2012

A u-healthcare remote diagnosis system is proposed for chronic disease and medical vulnerable groups check the health systematically and support for the most optimal environment to improve the quality of life. The u-healthcare remote diagnosis system using wireless measure the thoracic sound in the chest. And this is demonstrated that the system using radio frequency is not be affected by the electromagnetic wave with the use of an experiment and by confirming that this u-healthcare remote diagnosis system can not affect the doctors and the patients.

• Proceedings of the Korean Fiber Society Conference
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• 2002.04a
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• pp.355-358
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• 2002

고분자가 절연재료로서 사용되는 이유는 전기를 통하지 않는 절연특성을 지니고 있기 때문이며 이러한 성질은 고분자가 금속재료와 구별되는 가장 큰 특징이다. 그러나 1964년 W. A. Little 이 발표한 공액 이중결합구조를 가진 화합물은 전도성 고분자가 될 수 있다는 가설을 바탕으로 전도성 고분자에 관한 많은 연구가 진행 중에 있다. 전도성 고분자는 절연체로서의 응용에만 한정되어왔던 기존 고분자물질들과 달리 가볍고 저렴하며 단일결합과 이중결합을 교대로 하고 있는 공액 고분자 구조를 가지고 있어 다양한 화학적 합성방법에 의해 전기전도도, 유전상수, 결정 등의 물리적 성질을 조절할 수 있으며, 금속의 전기적, 자기적, 광학적 특성과 고분자의 기계적 성질을 동시에 가지므로 배터리, 축전기, 트랜지스터, 광전소자, 전자파 차폐제 등 플라스틱 전자소재의 실용적으로 인해 산업체에서도 높은 관심의 대상이다. (중략)

• Journal of the Korean Magnetics Society
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• v.5 no.6
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• pp.947-951
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• 1995

The electromagnetic interference is prevented by the high magnetic loss of the ferrite. The absorbing property of electromagnetic wave could be improved by the ferrite that has a finer and more uniform microstructure. The thermal decomposition of organic acid salt provided the uniform composition and fine powder. The absorbing properties of electromagnetic wave were evaluated by the relative complex permeability, permittivity, and the attenuation which is calculated from the results of network analyzer. The permeability and permittivity were increased with increase of the density and with decrease of the grain size. The matching thickness could be reduced with increasing sintered temperature. The attenuation of the Cu-Ni-Zn ferrite showed over 20dB when the matching thickness and the matching frequency range were 6.75mm and from 160MHz to 640MHz, respectively.

• Aerospace Engineering and Technology
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• v.12 no.1
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• pp.46-53
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• 2013

In this study, the analysis of electromagnetic environment of goheung aviation center was performed. If the test object has restrictions to be tested in indoor test facility, open area test site can be used to perform EMC test. Open area test site shall have no obstacles that can generate or reflect the electric field so as to prevent the measurement result from being influenced by unnecessary field. Goheung aviation center is surrounded by fields, and has no buildings that can reflect electric field, so the center can be a good candidate for open area test site. Ambient noise at Goheung aviation center was measured, and the result show that the center has good electromagnetic environment to perform EMC test for large volume object.