• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2000.10a
• /
• pp.186-189
• /
• 2000

In this paper, we have designed a bandpass filter to apply the downconverter of the K-band Mu-hung-hwa satellite. To pass only the 25-30% of the bandwidth at the center frequency of 19.6GHz, we have designed a six-order interdigital bandpass filter using microstrip lines. Simulation result of optimization show that insertion loss is -0.275dB and reflection coefficient is -20.95dB at the passband frequency. measurement is determined center frequency, 19.150Hz, insertion loss, -4.1dB, input reflection coefficient. -l5dB and output reflection coefficient -l6dB.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.45 no.2
• /
• pp.135-139
• /
• 2008

In this paper, tunable SC(switched capacitor) 2nd order bandpass $\Sigma-\Delta$(Sigma-Delta) modulator with novel architecture that can adjust the IF band center frequency by one coefficient value is proposed for data conversion in the IF(Intermediate Frequency) band. Its architecture can optionally adjust all the 2nd order noise transfer function in comparison with the conventional architecture. In order to adjust the center frequency, the conventional architecture needs the two variable coefficient values, basic clock and eight clocks. On the other hand, the proposed architecture can adjust the center frequency by one variable coefficient value and basic clock only.

• Journal of Korea Multimedia Society
• /
• v.7 no.11
• /
• pp.1515-1520
• /
• 2004

In this paper, a new continuous-time bandpass active filter for lour-voltage applications is proposed. The active filter is composed of the CMOS complementary cascode circuit which can increase trans-conductance of an active element. These results are verified through the 0.25$\mu\textrm{m}$ CMOS n-well parameter hspice simulation. As a result, the gain and the unity gain frequency is 42dB and 200MHz respectively in the integrator. Additionally, center frequency of the bandpass active filter is 747kHz. And also bandwidth of the filter is 649kHz on 2V supply voltage.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.46 no.9
• /
• pp.74-80
• /
• 2009

This paper describes a $2{\sim}6GHz$ CMOS frequency synthesizer that employs only one LC-tank voltage controlled oscillator (VCO). For wide-band operation, optimized LO signal generator is used. The LC-tank VCO oscillating in $6{\sim}8GHz$ provides the required LO frequency by dividing and mixing the VCO output clocks appropriately. The frequency synthesizer is based on a fractional-N phase locked loop (PLL) employing third-order 1-1-1 MASH type sigma-delta modulator. Implemented in a $0.18{\mu}m$ CMOS technology, the frequency synthesizer occupies the area of $0.92mm^2$ with of-chip loop filter and consumes 36mW from a 1.8V supply. The PLL is completed in less than $8{\mu}s$. The phase noise is -110dBC/Hz at 1MHz offset from the carrier.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.25 no.5
• /
• pp.362-367
• /
• 2005

Ultrasonic backward radiation profile is frequency-dependent when the incident region has deptional gradient of acoustical properties or multi-layers. Until now, we have measured the profiles of principal frequencies of an used transducers so that it was not easy to characterize the frequency dependence of the SAW(surface acoustic wave) from the backward radiation profile. We tried to measure the spectral backward radiation profiles using DFP(digital filer package) in a Lecroy DSO(digital storage oscilloscope). The measured spectral profiles showed that the steel specimen of #1200 surface treatment have 2% SAW velocity dispersion of the loaded case and the severly rusty steel specimen have the very big changes in the shape and pattern of the spectral profile. It is concluded that the spectral backward radiation profiles could be very effective tool to evaluate the frequency dependence of surface area.

• Proceedings of the KIEE Conference
• /
• 2004.07d
• /
• pp.2164-2166
• /
• 2004

QFT는 플랜트의 변동을 고려하여 주파수 영역에서 설계하는 제어기법으로 파라미터의 변화 및 외란에 강인한 제어기 설계에 적합한 제어기 설계 방법이다. 본 논문에서는 종축 방향의 항공기 무게 중심이 변화하는 범위에 대하여 요구 비행성(Flying Quality)을 만족하도록 하는 강인한 QFT 제어기의 설계기법을 제안하였다. 시뮬레이션을 통하여 제안한 QFT 제어기가 무게중심의 변화 범위에서 주어진 비행성능을 만족함을 확인하였다.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.43 no.2
• /
• pp.339-345
• /
• 1994

A new filter-bank is proposed in order to track center frequency of narrow band signal. The two banks are connected in series-parallel. The master filter bank which is made of traditional filter bank detects the center frequency roughly. And the performance for tracking center frequency is greatly improved by the slave filter bank which is based on energy-difference estimator. Computer simulations show that it achieves a good tracking accuracy.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2001.05a
• /
• pp.823-827
• /
• 2001

인체에 영향을 미치는 진동을 분류하는데 가장 중요한 기준은 주파수이다. ISO의 인체진동관련 규격에서는 인체에 영향을 미치는 거동을 저주파수 운동(0.63Hz이하)과 진동(1~80Hz)으로 나누고 있다［1］. ISO 2631에서는 주파수별로 인체에 미치는 영향을 그림1과 같이 가중치로 정의하여 제시하고 있다. 저주파수 영역의 운동은 외부 거동(주로 수평방향)에 대하여 자세를 유지하기 위해 힘Tm게 되므로 물리적인 피로감을 줄 뿐만 아니라 'Motion sickness'란 증상을 유발한다.(중략)

• The Journal of the Acoustical Society of Korea
• /
• v.17 no.3
• /
• pp.37-46
• /
• 1998

본 연구에서는 압전 세라믹인 PZT를 이용하여 두께 진동모드의 다중모드 필터를 설계, 제작하였다. 다중모드 세라믹필터의 등가회로를 설계하였고, 이를 이용하여 설계변수 인 물성변수와 형상변수에 따른 필터전달특성의 경향을 분석하였다. 이를 바탕으로 10.7MHz의 중심주파수를 가지는 세라믹필터를 제작하였고, 설계변수 중에서 압전세라믹 기 판과 전극형상의 변화에 따른 필터의 전달특성의 변화를 실험적으로 검증하였다. 본 연구를 통한 경향분석결과는 다양한 진동모드와 다양한 주파수대를 가지는 다중모드 필터를 설계하 는데 있어서 유용한 도구로 사용될 수 있을 것이다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2003.10a
• /
• pp.637-640
• /
• 2003

무선인식기술은 제품에 부착된 칩의 정보를 주파수를 이용해 읽고 쓸 수 있는 무선주파수인식으로 사람, 상품, 차량 등을 비 접촉으로 인식하는 기술이다. 이러한 무선인식관련 기술의 급격한 발달로 RFID(Radio Frequency IDentification) 시스템이 기존 바코드 중심의 상품식별시스템을 대체할 것으로 판단되므로 이에 대한 무선인식 구성과 기능, 적용분야, 표준화 등을 검토하기로 한다.