• 한국정보통신학회논문지
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• 제14권11호
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• pp.2397-2402
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• 2010

본 논문에서는 800MHz 대역에서 다양한 시간자연 특성을 갖는 유전체 공진기 대역통과 필터를 설계 및 제작하였다. 각각의 경우에 삽입손실은 모두 2dB 이내이었고 ripple은 0.2dB 이내이었으며 반사손실은 20dB 이상의 값을 가지는 우수한 특성을 보였다. 지연시간의 경우에는 각각 6ns, 12ns, 20ns를 구현하였으며 이때 평탄도의 범위는 1ns 이내이었다. 또한 유전체 블록이 2-hole을 갖는 경우에는 2~4ns의 범위를 갖는 것을 확인하였으며 각각의 유전체 필터를 조합하여 다양한 지연시간을 갖는 유전체 공진기 필터를 구현하였다.

• International Journal of Fluid Machinery and Systems
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• 제3권1호
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• pp.11-19
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• 2010

The performance of the crossover system of a centrifugal compressor stage consisting of static components of $180^{\circ}$ U-bend, return channel vanes and exit ducting with a $90^{\circ}$ bend is investigated. This study is confined to the assessment of performance of the crossover system by varying the shape of the return channel vanes. For this purpose two different types of Return Channel Vanes (RCV1 and RCV2) were experimentally investigated. The performance of the crossover system is discussed in terms of total pressure loss coefficient, static pressure recovery coefficient and vane surface pressure distribution. The experimentation was carried out on a test setup in which static swirl vanes were used to simulate the flow at the exit of an actual centrifugal compressor impeller with a design flow coefficient of 0.053. The swirl vanes are connected to a mechanism with which the flow angle at the inlet of U-bend could be altered. The measurements were taken at five different operating conditions varying from 70% to 120% of design flow rate. On an overall assessment RCV1 is found to give better performance in comparison to RCV2 for different U-bend inlet flow angles. The performance of RCV2 was verified using numerical studies with the help of a CFD Code. Three dimensional sector models were used for simulating the flow through the crossover system. The turbulence was predicted with standard k-$\varepsilon$, 2-equation model. The iso-Mach contour plots on different planes and development of secondary flows were visualized through this study.

• 한국전자파학회논문지
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• 제24권3호
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• pp.259-269
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• 2013

본 논문에서는 다양한 기판 집적 도파관 전송선 두께를 가지는 시스템에 적용을 위해서 천공된 기판 집적 도파관 다단 E-plane 변환기를 제안한다. 본 제안 구조는 ${\lambda}_g/4$ 임피던스 변환기 원리를 적용하여 ${\lambda}_g/4$ 길이 내에 천공을 삽입한다. 천공된 기판 집적 도파관은 도파관 내부의 낮아진 capacitance를 통해 특성 임피던스가 증가되어 E-plane 변환기로 구현된다. 또한, 체비셰프 다항식을 적용하여 구현한 천공된 기판 집적 도파관 다단 E-plane 변환기는 대역폭을 개선하였다. 천공된 기판 집적 도파관 2단 E-plane 변환기는 11.45~13.6 GHz의 주파수 대역에서 삽입 손실 $1.57{\pm}0.11$ dB, 입력 반사 손실은 15 dB 이상으로 나타났다.

• ETRI Journal
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• 제26권6호
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• pp.589-596
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• 2004

Packaging technologies for a broadband and narrowband modulator with a traveling wave electro-absorption modulator (TWEAM) device were developed. In developing a broadband modulator, the effects of the device and packaging designs on the broadband performance were investigated. The optimized designs were obtained through a simulation with the result that we developed a broadband modulator with a 3 dB bandwidth of 38 GHz in the electrical-to-optical (E/O) response, an electrical return loss of less than -10 dB at up to 26 GHz, an rms jitter of 1.832 ps, and an extinction ratio of 5.38 dB in a 40 Gbps non-return to zero (NRZ) eye diagram. For analog application, the effect of the RF termination scheme on the fractional bandwidth was studied. The microstrip line with a double stub as a matching circuit and a laser trimming process were used to obtain an $S_{11}$ of -34.58 dB at 40 GHz and 2.9 GHz bandwidth of less than -15 dB.

• Journal of electromagnetic engineering and science
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• 제5권3호
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• pp.112-116
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• 2005

This paper presents a broadband two-stage low noise amplifier(LNA) operating from 3 to 10 GHz, designed with 0.18 ${\mu}m$ RF CMOS technology, The cascode feedback topology and broadband matching technique are used to achieve broadband performance and input/output matching characteristics. The proposed UWB LNA results in the low noise figure(NF) of 3.4 dB, input/output return loss($S_{11}/S_{22}$) of lower than -10 dB, and power gain of 14.5 dB with gain flatness of $\pm$1 -dB within the required bandwidth. The input-referred third-order intercept point($IIP_3$) and the input-referred 1-dB compression point($P_{ldB}$) are -7 dBm and -17 dBm, respectively.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 하계종합학술대회 논문집(2)
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• pp.61-64
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• 2002

We have optimally designed and implemented by a monolithic microwave integrated circuit(MMIC) the low noise amplifier(LNA) of 5.8GHz band composed of receiver front-end(RFE) in a on-board equipment system for dedicated short range communication using a depletion-mode GaAs MESFET. The LNA is provided with two active devices, matching circuits, and two drain bias circuits. Operating at a single supply of 3V and a consumption current of 18㎃, The gain at center frequency 5.8GHz is 13.4dB, Noise figure(NF) is 1.94dB, Input 3rd order intercept point(lIPS) is 3dBm, and Input return loss(5$_{11}$) and Output return loss(S$_{22}$) is -l8dB and -13.3dB, respectively. The circuit size is 1.2$\times$O.7$\textrm{mm}^2$.EX>.>.

• Journal of electromagnetic engineering and science
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• 제19권1호
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• pp.64-70
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• 2019

In this study, a compact series-fed center-fed open-stub (SFCFOS) linear array antenna for K-band applications is presented. The antenna is composed of a single-line 10-element linear array. A symmetrical Chebyshev amplitude distribution (CAD) is used to obtain a low sidelobe characteristic against a uniform amplitude distribution (UAD). The amplitude is controlled by varying the width of the microstrip patch elements, and open-ended stubs are arranged next to the last antenna element to use the energy of the radiating signal more effectively. We insert a series-fed stub between two patches and obtain a low mutual coupling for a 4.28-mm center-to-center spacing ($0.7{\lambda}$ at 21 GHz). A prototype of the antenna is fabricated and tested. The overall size of the uniform linear array is $7.04{\times}1.05{\times}0.0563{\lambda}_g^3$ and that of the Chebyshev linear array is $9.92{\times}1.48{\times}0.0793{\lambda}_g^3$. The UAD array yields a ${\mid}S_{11}{\mid}$ < -10 dB bandwidth of 1.33% (20.912-21.192 GHz) and 1.45% (20.89-21.196 GHz) for the CAD. The uniform array design gives a -23 dB return loss, and the Chebyshev array achieves a -30.68 dB return loss at the center frequency with gains of 15.3 dBi and 17 dBi, respectively. The simulated and measured results are in good agreement.

• 방송공학회논문지
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• 제16권3호
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• pp.483-489
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• 2011

본 논문에서는 광대역, 양호한 복사패턴, 그리고 고이득 특성을 갖는 새로운 안테나를 제안하였다. FDTD(Finite Difference Time Domain) 법을 이용하여 본 안테나를 해석하였으며, 안테나의 파라메타는 최대대역폭을 갖도록 최적화 설계하였다. 측정한 결과, 안테나의 대역폭은 0.839 옥타브(S11${\leq}$-10 dB). 그리고 제안된 안테나의 측정된 교차편파 복사패턴은 -25dB이하의 우수한 특성을 보였다. 안테나의 측정된 반사손실과 복사패턴 특성도 나타내었으며, 측정된 대역폭 특성은 FDTD 결과와 비교적 잘 일치하였다. 제안된 안테나는 MIMO, LAN, 의료기기, 그리고 방송용 시스템에 적용할 수 있다.

• 한국실내디자인학회논문집
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• 제13권3호
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• pp.11-16
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• 2004

Adolf Loos studied at the Dresden Institute of Technology. He lived in America from 1893 to 1896. On his return to Vienna, hi worked for a year with the architect, Carl Mayreder. From 1897, he wrote extensively on design and architectural matters. In 1908, his famous article "Ornament and Crime"(Ornament und Verbrechen) was published, in which he linked the use of excessive decoration to a debasement of society. For Adolf Loos, it was a question not of renunciation of every ornament, but of the liberation from superfluous ornament. Where ornament was pastes on only, without connection with the subject or the building, and where ornament was not honest with the hand put on, the ornament is supposed to be removed. Onto the place of the ornament the joy of the material and the shaping should step. That the opinion of Adolf Loss is not correctly understood Is due on the one hand to the concentration on the 'ornament and crime' too very much. On the other hand his extreme Position is supposed to be understood more as thinking-impulse, more as provocation.ovocation.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2007년도 춘계종합학술대회
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• pp.441-444
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• 2007

In this paper, the resonance characteristics of ZnO-based film bulk acoustic resonator (FBAR) devices with high-quality multi-layer reflectors are proposed. The ultrathin Cr film $(300\;\AA-thick)$ between $SiO_2$ film and W film is formed by a sputtering-deposition in order to enhance the adherence at their interfaces. The resonance frequency was observed to vary with the number of the reflectors. This seems to be attributed to the change in the effective thickness of the ZnO film. Also, increasing the number of layers has led to a significant improvement of the series/parallel quality factor.