• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.349-349
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• 2008

유비쿼터스 시대를 맞이하여 현재의 전자제품은 고주파 환경에서의 소형화된 마이크로파 소자를 요구하고 있다. 현재 구현되고 있는 마이크로파 소자의 형태는 여러 가지 전송선로 중에 하나로서 금속의 그라운드면 위에 유전체 막을 형성하고 그 위에 금속선을 정밀하게 패터닝하여 각 종 소자를 연결하는 microstrip line의 형태가 많이 사용된다. 이러한 microstrip line 형태의 소자를 설계할 시에 소자 자체의 구조나 유전체 막이 그 소자의 성능을 크게 좌우한다. 여기서 유전체 막은 신호선과 그라운드면 간의 전자파를 집중시켜주어 방사손실을 줄여주는 역할을 한다. 유전체 막의 두께는 소자의 전체적인 크기를 결정하는 요인이 된다. 이는 유전체 막의 두께가 감소할 경우 50 $\Omega$ 임피던스 매칭을 위해 막 위에 형성되는 소자들의 선폭도 동시에 줄여야 하므로 소자의 소형화도 가능 하여진다. 하지만 유전체 막의 두께가 감소할 경우 전자파가 유전체 막에 집중되지 못하여 방사손실이 커지게 되고 소자의 성능이 저하된다. 이런 점을 고려할 때 소자의 소형화를 만족시키면서 동시에 소자의 성능을 유지할 수 있는 유전체 막의 최적화 두께에 대한 연구가 필요하다. 볼 연구에서는 유전체 막의 최적화 두께를 제시하기 위해 대표적 마이크로파 소자인 Edge-Coupled Filter에 대하여 3-D Electromagnetic Simulator로 설계하고 유전체 막의 두께와 Filter 성능 간의 관계를 연구하였다. Filter의 성능은 유지하도록 하면서 유전체 막의 두께를 감소시켜 나간 결과, 약 30 ~ 40 ${\mu}m$ 의 최적화 두께를 얻을 수 있었다. 한편 30 ~ 40 ${\mu}m$ 두께의 후막 공정을 고려할 때 기존의 성막공정으로는 성막시간, 공정의 난이도, 공정온도 등의 면에서 난점이 존재하며 이러한 점들을 극복할 수 있는 Aerosol Deposition Method의 적용 가능성에 대해서 연구하였다.

• Journal of electromagnetic engineering and science
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• v.16 no.1
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• pp.7-12
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• 2016

This paper presents the design of a negative group delay circuit (NGDC) using the filter synthesis approach. The proposed design method is based on a frequency transformation from a low-pass filter (LPF) to a bandstop filter (BSF). The predefined negative group delay (NGD) can be obtained by inserting resistors into resonators. To implement a circuit with a distributed transmission line, a circuit conversion technique is employed. Both theoretical and experimental results are provided for validating of the proposed approach. For NGD bandwidth and magnitude flatness enhancements, two second-order NGDCs with slightly different center frequencies are cascaded. In the experiment, group delay of $5.9{\pm}0.5ns$ and insertion loss of $39.95{\pm}0.5dB$ are obtained in the frequency range of 1.935-2.001 GHz.

• Proceedings of the Optical Society of Korea Conference
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• 2009.10a
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• pp.373-374
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• 2009

• Proceedings of the Optical Society of Korea Conference
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• 2006.07a
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• pp.55-56
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• 2006

• Journal of the Optical Society of Korea
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• v.17 no.1
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• pp.109-109
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• 2013

• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.10
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• pp.1169-1174
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• 2014

In this paper, for improving the performance of selecting and the sensitivity of the L-Band microwave radiometer for remote sensing of soil-moisture, the harmonic-suppressed hairpin bandpass filter is described. As the harmonic frequencies of the SIR can be controlled by the ratio of the impedance and electrical length, SIRs are used in the hairpin BPF for suppressing harmonics. Manufactured harmonic-suppressed hairpin BPF has the SIRs of three types and its harmonic is suppressed under 35 [dB] until 5 times of the center frequency of 1390 [MHz].

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.2
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• pp.122-127
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• 2013

Layered-type dielectric waveguide filters were designed. As the order of layers increased the fabrication process for dielectric waveguide filters which the resonator parts were connected by the lateral direction has many difficulties. The proposed structure in this report was designed based on the layered-type for the some parts of resonators. The size of layered-type dielectric waveguide filters installed on the PCB surface were reduced at 25% as compared with the usual waveguide filters by using a relative dielectric constant 22.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.581-584
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• 2002

In this work, a CPW resonator was designed and fabricated to investigate the basic microwave properties, such as effective dielectric constant, of BST thin films. Their properties were used as basic data to simulate and design CPW tunable bandpass filter. We also report on gold/$Ba_{0.5}Sr_{0.5}TiO_3$(BST) ferroelectric thin film C-band tunable bandpass filters(BPFs) designed and fabricated on magnesium oxide substrates using CPW structure. The 2 pole filter was designed for a center frequency of 5.88 GHz with a bandwidth of 9 %. The BST based CPW filter offers a high sensitivity parameter as well as a low loss parameter. The tuning range for the bandpass filter with CPW structure was determined to be 170 MHz.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.26 no.1
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• pp.48-57
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• 2016

Objectives: This study was conducted to evaluate the accuracy and precision of airborne metal analysis using polyvinyl chloride(PVC) membrane filter by pretreatment methods. Methods: A total of 75 spiked PVC samples for Cr, Fe and Mn ranged from 6 ug/sample to 40 ug/sample were used to evaluate recovery rates for three pretreatment methods: acid extraction, hot plate ashing and microwave digestion. For Mn, an additional 75 spiked mixed cellulose ester(MCE) membrane filters were analysed to compare the recovery rates of PVC samples. All samples were analysed with an inductively coupled plasma optical emission spectrometer(ICP-OES) and manganese samples were additionally analyzed by atomic absorption spectrometer(AAS). Results: The overall mean recovery rates of PVC samples for Cr, Fe and Mn were 90% or higher regardless of pretreatment methods, but there were statistically significant differences in recovery rates for Cr(p<0.05) and Mn(p<0.01) samples by pretreatment methods. The biases and the coefficient variations of PVC samples for three metals pretreated with three kinds of pretreatment methods ranged from 1.7% to 4.7% and from 1.6% to 6.5%, respectively. The manganese PVC samples pretreated by microwave digestion and analyzed with ICP-OES had the lowest bias at 1.9% and also showed lower bias than the bias for MCE samples, 2.7%. Conclusions: In order to accurately analyze the metals sampled with PVC membrane filters, microwave digestion and ICP-OES can be recommended.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.10
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• pp.958-963
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• 2013

Ceramic dielectric waveguide duplexer was developed. Duplexer was designed in order to minimize the muture interferences between transmission port and receive port of bandpass filter. The design method for antenna port was determined by the transmission loss and calibrated the length of resonator of recriving filter. We used the ceramic powder of dielectric constant 9.46 and installed SMD type on PCB board.