• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 하계종합학술대회 논문집(2)
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• pp.249-252
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• 2002

we have studied the characteristics of PHEMT's with gate recess etching method. The DC characterization of PHTMT fabricated with the wide single recess methods is a maximum drain current density of 319.4 ㎃/mm and a peak transconductance of 336.7 ㎳/mm. The RF measurements were obtained in the frequency range of 1~50GHz. At 50GHz, 3.69dB of 521 gain were obtained and a current gain cut-off frequency(f$_{T}$) of 113 CH and a maximum frequency of oscillation(f$_{max}$) of 172 Ghz were achieved from this device. On the other hand, a maximum drain current of 367 mA/mm, a peak transconduclancc of 504.6 mS/mm, S$_{21}$ gain of 2.94 dB, a current gain cut-off frequency(f$_{T}$) of 101 CH and a maximum frequency of oscillation(f$_{max}$) of 113 fa were achieved from the PHEMT's fabricated by the .narrow single recess methods.methods.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.809-812
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• 2001

We were fabricated of NiCr thin film resistors on A1$_2$O$_3$and SiO$_2$/Si substrates by dc magnetron sputtering system. The AC characteristics of resistors were studied. The cut-off frequency were found >10 MHz for the resistors with 39 ohm value of Alumina substrates, but the cut-off frequency were found 400 kHz for the resistors with 168 ohm value of SiO$_2$/Si substrates. In high frequency applications, the substrate selection is the most important factor.

• 제어로봇시스템학회논문지
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• 제17권2호
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• pp.125-130
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• 2011

This paper shows a method to design complementary filter using least square. The complementary filter is one of useful filters estimating angle. The basic concept of this filter is to enhance advantages of each sensor that angle detecting using a gyroscope has good accuracy at a high frequency and an accelerometer at a low frequency. When designing complementary filter, the most commonly used method is using cut-off frequency. However, it may be not easy to obtain a cut-off frequency. This paper presents a systematic method to determine the coefficients of the complementary filter using well-known linear least squares minimizing error between estimating angle and true angle.

• 대한전자공학회논문지
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• 제21권1호
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• pp.32-37
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• 1984

본 논문에서는 저역 통과 특성을 나타내는 것으로 알려져 있는 이동 평균 여파기의 마이크로프로세서 구성에 대한 실제적이고 간단한 기법을 연구한 것이다. 설계의 편의를 위하여 이동 평균 여파기에 대한 차단 주파수의 근사식과 필터링 알고리즘도 제시하였다. 상용 마이크로프로세서 Z-80을 사용한 실험 시스템의 몇 가지 실험결과를 제시했다. 고주파 잡음이 효과적으로 제거된 것이 확인되었으며 차단 주설수의 근사식의 결과는 실측결과와 거의 일치됨이 확인되었다.

• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2004년도 춘계학술대회
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• pp.172-175
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• 2004

This paper analyzes the effects of Ge profiles shape of SiGe heterojunction bipolar transistors (HBT's) for high frequency application. Device simulations using ATLAS/BLAZE for the SiGe HBT with trapezoidal or triangular Ge profile are carried out to optimize the device performance. An HBT with $15\%$ triangular Ge profile shows higher cut-off frequency and DC current gain than that with $19\%$ trapezoidal Ge profile. The cut-off frequency and DC gain are increased from 42GHz to 84GHz and from 200 to 600, respectively. The SiGe HBT has been fabricated using a production CVD reactor.

• 한국강구조학회 논문집
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• 제8권4호통권29호
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• pp.19-29
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• 1996

In this paper, it is presumed that the stress time history was generated by simulation method and investigated compatibility in regard to the reappearance of stress time history. In this procedure, the identified frequency distribution of stress range of the steel railroad bridge varies with the rational values of cut off point and bar width. Thus, we show variable aspect of the equivalent stress range results from change of cut off point and bar width. In addition, we analyze the variable of RMC and RMS model due to the cut off point and bar width of the measured stress history which influencs the prediction of fatigue life in the steel railroad bridge. The simulated stress time history is carried out by the superposition method incorporating the vertical load with rotation moment obtained from the Hermition interpolation function, and compared with developing stress results from measured maxi mum stress. Through this study, we can estimate the remaining fatigue life from a safety point of view and comparative accuracy.

• 한국정보통신학회논문지
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• 제16권3호
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• pp.565-570
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• 2012

본 논문은 LTE-Advanced 시스템을 위한 멀티채널을 선택할 수 있는 저역통과 필터를 제안한다. 제안하는 저역통과 필터는 5 MHz, 10 MHz, 그리고 40 MHz의 3가지 모드의 차단주파수를 제공하며 Active-RC 5차 Chebyshev 구조로 설계되었다. 저전력을 확보하면서 40 MHz의 높은 차단 주파수를 확보하기 위해서 부성 저항을 가지는 PMOS Cross-Connection Load를 사용한 연산증폭기를 필터에 적용하였다. 더불어 공정, 전압, 그리고 온도에 의한 각각의 차단주파수 변화에 대응할 수 있도록 각각 3-bit 제어 가능한 튜닝회로를 추가하였다. 제안하는 필터는 0.13-${\mu}m$ CMOS 공정을 사용하여 설계하였으며 1.2 V 전압에서 총 20.9 mW 전력을 소모한다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 C
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• pp.1835-1837
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• 2004

The UHF electromagnetic waves excited by PD pulses propagate along the GIS busbar not only TEM mode, but also TE and TM mode. Generally the waves detected by the UHF sensors are those of high order modes and such waves can only propagate the higher than cut-off frequency. In this paper, computed cut-off frequency of 362[kV] GIS by each modes and simulated electromagnetic field of each propagation modes by FEM(Finite Element Method) program. Frequency band of each TEmn/TMmn modes were determinated by simulation results and were discussed optimal position of UHF sensor from this results.

• 대한전기학회논문지:전력기술부문A
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• 제53권11호
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• pp.624-629
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• 2004

The UHF electromagnetic waves excited by PD pulses propagate along the GIS busbar not only TEM mode, but also TE and TM mode. Generally the waves detected by the UHF sensors are those of high order modes and such waves can only propagate higher than cut-off frequency. In this paper, the cut-off frequency of 362[kV] GIS for each modes is computed and the electromagnetic field of each propagation modes is simulated by FEM(Finite Element Method) program. Frequency band of each TEmn/TMmn modes was determinated by simulation results and was discussed optimal position of UHF sensor from this results.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2005년도 전기학술대회논문집
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• pp.1166-1169
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• 2005

This paper describes a new transient voltage suppressor(TVS) with a low insertion loss and a high cut-off frequency to protect antenna circuit from transient voltages. Conventional protection devices have some problems such as a low frequency bandwidth and a high insertion loss. In order to improve these limitations, a coaxal type TVS, which consists of a gas tube is developed. The performance of the proposed transient voltage suppressor is tested by using a combination surge generator specified in IEC 61000-4-5 standard and by using a network analyzer of 40 MHz ${\sim}$ 5 GHz bandwidth. From the experimental results, it is confirmed that the proposed TVS has an enough protection performance in a low insertion loss and a high cut-off frequency.