• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.435-438
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• 1999

Nowadays, the inverter for CCFL(Cold-Cathode Fluorescent Lamp) driver is needed as form of compact size, low loss and high efficiency. This paper deals with comparison of characteristics of the electromagnetic push-pull type inverter and the piezoelectric half-bridge inverter for a CCFL driver. From the experimental results, the piezoelectric inverter is proven as more efficient than conventional electromagnetic inverter.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2000.11a
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• pp.229-232
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• 2000

In this study, An active band grass filter for 2.14GHz have been designed with MMIC using negative resistance circuit. The negative resistance element was realized with a common-drain FET with series inductive feedback. The designed active filter showed an insertion loss of 0dB at 2.14GHz and a 3-dB bandwidth of 125MHz.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2000.11a
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• pp.238-242
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• 2000

In this paper, the method for dielectric constant and less tangent measurements of microwave substrates using a microstrip line is presented. The two samples of an open-ended line and a short-ended tine are made and complex propagation constant is evaluated from the one-port scattering parameter measurements. This method has been automated fully using a personal computer and a vector network analyzer.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2001.11a
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• pp.161-164
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• 2001

본 논문에서는 주어진 주파수대역에서 우수한 원편파 특성을 가지고 광대역에서 저반사 손실을 가지는 이종대역 안테나 피드용 원형도파관 유전체 편파기의 설계기법을 제시하였다. 양호한 편파특성을 위한 유전체판 두께와 원형 도판관 직경의 결정방법을 제시하였다. 또한 이종 대역 안테나 피드용으로 광대역에서 저반사 손실을 가지기 위한 유전체 형상 설계기법을 제시하였다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.5
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• pp.680-687
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• 1999

An extensive study on miniaturized bandpass filter(BPF) appropriate for mobile communication systems is presented in this paper. The miniaturization has been accomplished by incorporating low-loss high-index materials inside a resonating cavity fabricated in silicon substrate using micromachining etching techniques. By use of materials with dielectric constant $\varepsilon_r$=500, filters with volume less than 0.11 $mm^3$ have been designed at the center frequency of 5.8 GHz with 3.3% bandwidth. The electrical performances and design tolerances of these filters for a variety of materials and shapes are discussed and design guidelines are presented herein.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.2014-2015
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• 2007

This paper deals with design and analysis of thrust magnetic bearing. Using the solutions obtained from equivalent magnetic circuit, we predict the electromagnetic characteristics such as thrust, time constant and power loss according to design parameters. And then, using non-linear finite element analysis, a detailed design is performed considering saturation in order to meet requirements.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.8 s.99
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• pp.790-796
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• 2005

In order to accomplish a wireless communication of capsule endoscopy, an environment study in the human body and receiving antenna design have been performed. The proposed antenna is the loop antenna designed to minimize the propagation loss in multi-loss layer such as the human body and utilize the magnetic field. Considering the propagation loss in the human body, the frequency range is from 400 MHz to 500 MHz. Acorrrding to the FCC regulations, the permittivity and conductivity for each human tissue were extracted. We set up an equivalent model and make an aqueous solution which is replaced with the human body. Due to movement of capsule in the human body which propagation loss is extremly severe, an array antenna is required. Irrespective of the location of transmission antenna transmitting a signal of 1 mW, we confirme what it is possible for the enough signal detection as the average signal level of array antenna is -60 dBm.

• Journal of electromagnetic engineering and science
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• v.3 no.2
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• pp.86-90
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• 2003

A flat conversion loss in microwave mixer is hard to achieve if integrating with an image rejection filter(IRF). This is due to the change of termination condition with respect to the LO and IF frequency at RF port where the filter has 50 ohm termination property only in the RF band. This paper describes a flatness maintenance in the down mixer concerning a diode matching condition as well as an electrical length of embedding line at RF port. The implemented single balance diode mixer is suitable for a 23 ㎓ European Terrestrial Radio. RF, LO and fixed IF frequency chosen in this paper are 21.2∼22.4 ㎓, 22.4∼23.6 ㎓ and 1.2 ㎓, respectively. The measured results show a conversion loss of 8.5 ㏈, flatness of 1.2 ㏈ p-p, input P1㏈ of 7㏈m, IIP3 of 15.42 ㏈m with nominal LO power level of 10㏈m. The return loss of RF and LO port are less than - 15 ㏈ and - 12 ㏈, respectively and IF port is less than - 6 ㏈. LO/RF and LO/IF isolation are 18 ㏈ and 50 ㏈, respectively. This approach would be a helpful reference for designing up/down converter possessing a filtering element.

• Journal of Electrical Engineering and Technology
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• v.12 no.1
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• pp.91-99
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• 2017

In order to meet the thermal performance analysis accuracy requirements of high density permanent magnet synchronous motor (PMSM), a method of multi physical domain coupling thermal analysis based on control circuit, electromagnetic and thermal is presented. The circuit, electromagnetic, fluid, temperature and other physical domain are integrated and the temperature rise calculation method that considers the harmonic loss on the frequency conversion control as well as the loss non-uniformly distributed and directly mapped to the temperature field is closer to the actual situation. The key is to obtain the motor parameters, the realization of the vector control circuit and the accurate calculation and mapping of the loss. Taking a 48 slots 8 poles high density PMSM as an example, the temperature rise distribution of the key components is simulated, and the experimental platform is built. The temperature of the key components of the prototype machine is tested, which is in agreement with the simulation results. The validity and accuracy of the multi physical domain coupling thermal analysis method are verified.

• Journal of electromagnetic engineering and science
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• v.8 no.3
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• pp.129-133
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• 2008

An integrated passive device(IPD) technology by semi-insulating(SI)-GaAs-based fabrication has been developed to meet the ever increasing needs of size and cost reduction in wireless applications. This technology includes reliable NiCr thin film resistor, thick plated Cu/Au metal process to reduce resistive loss, high breakdown voltage metal-insulator-metal(MIM) capacitor due to a thinner dielectric thickness, lowest parasitic effect by multi air-bridged metal layers, air-bridges for inductor underpass and capacitor pick-up, and low chip cost by only 6 process layers. This paper presents the Wilkinson power divider with excellent performance for digital cellular system(DCS). The insertion loss of this power divider is - 0.43 dB and the port isolation greater than - 22 dB over the entire band. Return loss in input and output ports are - 23.4 dB and - 25.4 dB, respectively. The Wilkinson power divider based on SI-GaAs substrates is designed within die size of $1.42\;mm^2$.