• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 추계학술대회 논문집 전력기술부문
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• pp.38-40
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• 2003

This paper describes the integrated dynamic stability(IDS) program for tuning the power system controllers, such as PSS, AVR and so on. IDS consists of three modules; power flow module, PWRLF, to calculate large scale power system load flow solutions, IDS/PSS module to calculate eigenvalues and frequency response in the range of frequency from 0.2Hz to 2Hz, and IDS/NEA module to calculate eigenvalues in the range of frequency from 5.0Hz to 55Hz. In addition, IDS provides graphic user interface(GUI) in order to let the user handle and analyze the input data and the results of calculation with convenience.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 II
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• pp.1097-1100
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• 2003

Tunable thermo-optic filter for WDM system was designed and fabricated. The basic structure of the filter was a Fabry-Perot resonator and the center cavity layer was poly-Si. Quardraple layers of low and high refractive index materials were used as DBR mirrors. Tuning and transmission efficiencies was measured and compared with the simulation results. Tuning range of 9.4 nm can be obtained by 64.7$^{\circ}C$ temperature changes and tuning efficiency was 0.144nm/K. The filter is to be assembled onto the micro optical bench with fiber optical path.

• 대한전자공학회논문지
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• 제17권2호
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• pp.1-9
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• 1980

채널튜닝전압 자체를 기억시키는 종래의 전압합성방식을 개선, 10키이를 통하여 입력시킨 채널번호에 의해 튜닝전압을 계산하여 VHF 및 UHF 전대역에 실제채널번호를 표시하면서 직접접근선국(direct access channel selection)할 수 있는 회로를 설계하였다. 또한 본 회로는 택안(search)에 의한 미세튜닝 및 방송이 없을 경우의 표시를 자동적으로 행하며, 2개의 키이로 채널 전반을 순차적으로 선국할 수 있는 기능도 가지게 하였다.

• 한국통신학회논문지
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• 제22권1호
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• pp.81-88
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• 1997

Wavelength tunable, narrowbandwidth wvelength filters in compound semiconductor have been modeled, fabricated, and characterized. In order to obtain a narrow bandpass characteristics at 1.55.$\mu$m, a highly asymmertrical directional coupler structure composed of a strongly guided ridge waveguide and a weakly guided strip-loaded waveguide was used. The optimized filter structure modeling has been obtained by using the spectral index method, effective index method, and the coupled mode theory. Operation at a center wavelength a 1.537.mu.m with a bandwidth of 1.8nm and transfer efficiency of 50-70% is experimentally achieved. For the purpose of center wavelength tuning, the carrier injection in p-n diode structure has been theoretically investigated. It has been found that the tuning range of nanometer can be easily obtained by moderate amount carrier injection. We also found that the bandwidth becomes broad as the center wavelength tuning increases.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 C
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• pp.1143-1146
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• 1998

Static excitation systems with high gain and fast response times greatly aid transient stability. but at the same time tend to reduce small signal stability. The objective of the power system stabilizer(PSS) control is to provide a positive contribution to damping of the generator rotor angle swings, which are in a broad range of frequencies in the power system. Therefore, this paper shows the field test results for the GE's EX2000 PSS tuning on units at Seo-Incheon power plant. The test is to verify that the PSS response meets GE's design, criteria. The responses of generator terminal voltage, active power, field voltage and current were analyzed and PSS gain was tuned by 10 finally.

• Structural Engineering and Mechanics
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• 제33권3호
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• pp.339-355
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• 2009

The sealed, tuned liquid column gas damper (TLCGD) with gas-spring effect extends the frequency range of application up to about 5 Hz and efficiently increases the modal structural damping. In this paper the influence of several TLCGDs to reduce coupled translational and rotational vibrations of plan-asymmetric buildings under wind or seismic loads is investigated. The locations of the modal centers of velocity of rigidly assumed floors are crucial to select the design and the optimal position of the liquid absorbers. TLCGD's dynamics can be derived in detail using the extended non-stationary Bernoulli's equation for moving reference systems. Modal tuning of the TLCGD renders the optimal parameters by means of a geometrical transformation and in analogy to the classical tuned mass damper (TMD). Subsequently, fine-tuning is conveniently performed in the state space domain. Numerical simulations illustrate a significant reduction of the vibrations of plan-asymmetric buildings by the proposed TLCGDs.

• Communications for Statistical Applications and Methods
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• 제28권4호
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• pp.351-368
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• 2021

For a probabilistic model with positively skewed data, a lognormal distribution is one of the key distributions that play a critical role. Several lognormal models can be found in various areas, such as medical science, engineering, and finance. In this paper, we propose a new estimator for a lognormal mean and depict the performance of the proposed estimator in terms of the relative mean squared error (RMSE) compared with Shen's estimator (Shen et al., 2006), which is considered the best estimator among the existing methods. The proposed estimator includes a tuning parameter. By finding the optimal value of the tuning parameter, we can improve the average performance of the proposed estimator over the typical range of σ². The bias reduction of the proposed estimator tends to exceed the increased variance, and it results in a smaller RMSE than Shen's estimator. A numerical study reveals that the proposed estimator has performance comparable with Shen's estimator when σ² is small and exhibits a meaningful decrease in the RMSE under moderate and large σ² values.

• 대한전자공학회논문지SD
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• 제47권5호
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• pp.94-99
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• 2010

본 논문에서는 디지털 제어 발진기의 전력소모를 최적화하는 설계기법을 제안한다. 디지털 제어 발진기의 Coarse tuning 비트수와 Fine tuning 비트수를 조절하여 LSB Resolution, 주파수 범위, 선형성, 이식성에는 영향을 주지 않고 전력소모를 최적화한다. 이를 위해 제어 비트에 따른 디지털 제어 발진기의 전력소모 변화를 분석하였다. 본 논문에서는 0.13um 1.2V CMOS 라이브러리를 이용하여 제안한 설계기법을 적용한 경우와 그렇지 않은 경우를 모두 설계, 모의실험 및 검증하였다. 제안한 설계기법을 적용한 디지털 제어 발진기는 모의실험결과 283MHz부터 1.1GHz의 클록을 생성할 수 있으며, LSB Resolution은 1.7ps이다. 디지털 제어 발진기의 출력 주파수가 1GHz일 때 전력소모는 2.789mW이다.

• 전기전자학회논문지
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• 제28권3호
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• pp.445-450
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• 2024

본 논문에서는 0.15-㎛ GaAs pHEMT 공정을 이용하여 설계된 버랙터 없는 W-band(75-110 GHz) 전압제어 발진기(VCO)를 소개한다. 능동 인덕터를 활용하여 버랙터 없는 주파수 조절을 구현하였으며 능동 인덕터 회로는 게이트가 종단된 공통 게이트 스테이지를 이용하였다. 해당 능동 인덕터는 시뮬레이션 결과 기존의 버랙터 다이오드와 비교하여 넓은 주파수 조절 범위와 높은 Q-인자를 갖는다. 발진기 코어는 소스 피드백이 포함된 Colpitts 구조를 사용하였다. 구현된 버랙터 없는 W-band VCO의 측정 결과 88 GHz에서 5.7 dBm의 높은 출력 전력과 5.8 %의 주파수 조절 범위를 얻었으며 이 때 dc 전력 소모는 146 mW였다. 또한 해당 회로는 컴팩트한 레이아웃 디자인을 통해서 0.48 mm²의 작은 사이즈로 구현되었다.

• Journal of information and communication convergence engineering
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• 제15권1호
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• pp.1-6
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• 2017

In this study, we develop and experimentally evaluate an ultra-wideband (UWB) slot antenna with a polygon tuning stub. The proposed antenna consists of a polygon slot with a $50-{\Omega}$ feed line. The effects of various parameters of the polygon-shaped slot and the polygon tuning stub on UWB applications are investigated. The optimum parameters were obtained using the Ansys HFSS software. The results of the studies on the surface current distributions of the operating frequency bands were discussed. The proposed antenna is fabricated on an inexpensive FR-4 substrate with the overall dimensions of $28.0mm{\times}30.0mm$. The measured results confirm that the proposed antenna covers frequencies from 2.58 GHz to 13.27 GHz, which is the UWB frequency range. Further, the proposed UWB antenna also exhibited that omni-directionality in the H-plane gain varied from 1.185 to 7.246 dBi. The good antenna characteristics of the proposed antenna make it suitable for UWB system applications.