• 한국전기전자재료학회논문지
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• 제18권8호
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• pp.759-765
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• 2005

In this paper, developed isolator for gap filler is analyzed and designed using the simulation tool. Using the designed parameters, isolator is fabricated and tested in gap filler band. Temperature characteristics of isolator depend on magnet, YIG ferrite, and conductor etc. These require temperature stability and possible method of compensation for the temperature dependent effects. The temperature stabilization tries to use Ni-alloy. Developed isolator that compare with room temperature and high temperature characteristics has change fewer than 20 MHz. Implemented isolator shows more than 20 dB isolation characteristic at center frequency(2,650 MHz) and has 0.2 dB insertion loss in overall 100 MHz operating bandwidth. Return losses of input and output port are measured below -20 dB.

• 대한전기학회논문지
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• 제39권2호
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• pp.149-156
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• 1990

In DC electric railway systems, the feeding currrnt is not permitted to flow backward in almost all the substations and the pantograph voltages at the regenerating cars rise extremely by the voltage drop of the resistance of the feeder line. In order to prevent the overrise of the pantograph voltage in power regenerating cars, the squeezing circuits for the regenerative current are equipped and this leads to double losses, which are an extra worn-out of the brake-shoes and an ineffective use of regenerative power. In this study, the insertion of resistors in the feeder line system is proposed as a possible method for the effective utilization of the regenerative power in the electric railways. Also it is investigated how the output voltages of substations affect the effective use of regenertive capability. The investigation results show that the energy savings and the reduction of the worn-out of the brake-shoe can be achieved at the same time by the insertion of resistors in the feeder line system.

• 센서학회지
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• 제19권4호
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• pp.320-327
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• 2010

In this paper, electrostatically actuated direct contact type RF MEMS switches have been designed and demonstrated. As driving structures of the switch, cantilever, bridge, and torsion spring beam structures are used and the actuation voltage characteristics of the switches have been compared and discussed. The designed RF switches are fabricated with the surface micromachining technology using the electroplated gold and nickel structures. The characteristics of the fabricated switches are measured and analyzed. The switch, which is fabricated using the 510 ${\mu}m$-length bridge structure with the thickness of 1.5 ${\mu}m$, is actuated with 15 V driving voltage. The insertion losses are less than 0.2 dB over the measured frequency ranges from 0 to 20 GHz and the isolations are more than 30 dB.

• Journal of the Optical Society of Korea
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• 제9권3호
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• pp.99-102
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• 2005

Directional couplers of gradient-index plastic optical fibers were fabricated and characterized. In particular, we have employed a core-facet technique to make the directional couplers, which require mechanical side polishing and linkage. We have measured insertion loss, excess loss, and coupling ratio of the fabricated couplers as a function of polishing depth and coupling length. We found that polishing depth of $\~300{\mu}m$ and coupling length of $\~35mm$ are optimum conditions for minimizing the insertion and excess losses and for achieving 1: 1 coupling ratio.

• 한국ITS학회 논문지
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• 제12권6호
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• pp.37-43
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• 2013

본 논문에서는 SIR(Stepped Impedance Resonator) 구조를 이용한 초광대역(UWB:Ultra Wide Band) 개방형 스터브 대역통과 여파기를 제안한다. 제안한 개방형 스터브 대역통과 여파기는 초광대역을 구현하기 위해 스터브 위치에 SIR 구조를 적용하였으며 낮은 삽입손실을 갖는다. 제안된 대역통과 여파기의 대역폭은 중심 주파수 5.8GHz에서 103% 이고, 삽입 및 반사손실은 각각 0.17dB 및 13.1dB이며 전체의 크기는$21.6{\times}17.8mm^2$ 이다.

• 한국소음진동공학회논문집
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• 제21권4호
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• pp.357-364
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• 2011

In this study, ring-shaped acoustic resonators were proposed to be installed in a silencer to increase the acoustic performance of silencer in the low-frequency range. Evaluation of noise reduction performance of acoustic resonator arrays was carried out by measuring the random-incidence absorption coefficient. It was found that the absorption coefficient of resonator array was measured up to 1 at 125 Hz of 1/3-octave band center frequency. Insertion losses of silencers with ring-shaped acoustic resonator arrays were measured based on ISO 7235. The results were shown that the ring-shaped resonator could increase the insertion loss up to 13 dB without flow, whereas 7 dB when flow speed reached 15 m/s. As increasing the flow speed above 15 m/s, the effect of acoustic resonator decreased due to the effect of nonlinear air damping of the resonator. It was also found that the increment of pressure drop by the presence of resonator arrays was about 9 % at flow speed of 25 m/s.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.1
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• pp.119-122
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• 2003

This paper describes characteristics for insertion losses of Isolator have an effect on material parameter. One purpose of the paper is to present insertion loss on this resonator for magnetic loss, dielectric loss, magnetic field and saturation magnetization. Another is to study the effect of propeller resonator on response characteristics. In this paper, the analysis and measurement of the response characteristics were carried out for the isolator prototype. The measurement results agreed on the simulation results and acquire insertion loss $0.18\;{\sim}\;0.24dB$, return loss 27dB, isolation 27dB and bandwidth 500MHz on this condition saturation magnetization 550G, dielectric loss 0.0004, magnetic loss 20 and dielectric constant 14.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.951-954
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• 2006

This Study introduces the design of a reactive type silencer for reducing impulse noises emitted from a high voltage COS fuse of a transformer. When a high voltage COS fuse becomes a short circuit by the over current, the peak sound pressure level above 150dB(A) is generated at the distance of 2m from a COS Fuse. For the purpose of the reduction of impulse noise, in this study. the reactive type silencers have been utilized. The performance of noise reduction for them can be expressed by insertion loss. The reactive silencers have been tested for 23 different types with each different porosity, hole diameter and depth. From the experimental results, it is found that the reactive silencer has an excellent performance to greatly suppress the impulse noise. The one-stage, two-stage and three-stage reactive type silencers have been shown to have the insertion losses of about from 35dB (A) to 25dB(A).

• 한국전자파학회논문지
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• 제13권8호
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• pp.819-826
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• 2002

본 논문은 $Ba_{0.5}$Sr$_{0.5}$TiO$_3$(BST) 박막을 이용한 대역 통과 여파기를 설계, 제작한 것으로 마이크로스트립 과 코플래너 웨이브가이드(CPW), CBCPW 전송 선로 구조에서 각 구조의 여파기 특성을 비교하였다. 제작된 여파기는 전압 0V 인가시 각각 6.4 GHz, 6.14 GHz, 6.04 GHz의 중심 주파수와 6 dB, 4.41 dB, 5.41 dB의 삽입 손실이 측정되었으며, 40V 인가시 중심 주파수 6.61 GHz, 6.31 GHz, 6.21 GHz와 삽입 손실 7.33 dB, 5.83 dB, 6.83 dB로 나타났다. 본 논문에서 제작된 각각의 대역 통과 야파기는 가변 범위가 약 3 % - 8 %이며, 무선랜 대역에 응용할 수 있도록 설계 및 제작되었다.다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.385-386
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• 2008

In this paper, a simple dual band filter chip is designed with 0603 case size using IPD technology. The dual-band filter achieves high frequency band at 2.5 GHz and low frequency band at 1.8 GHz. The insertion losses in high frequency band and low frequency band are -0.195 dB and -0.146 dB, respectively. The return losses in these bands are -22.7 dB and -22.8 dB, respectively. The simple dual-band filter based on SI-GaAs substrate is designed within die size of about 1.3 $mm^2$.