• JSTS:Journal of Semiconductor Technology and Science
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• 제16권1호
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• pp.1-10
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• 2016

Drivers for LED MR16 retrofit lamps need to be compatible with the dimmers and electronic transformers which originally operated with the halogen lamps to be replaced. We present a two-stage MR16 LED driver consisting of a boost converter in the first stage and a buck converter in the second stage. Our design has been analyzed in the frequency domain using simulations to demonstrate that it effectively suppresses the high-frequency components of the AC output of the electronic transformer. Experiment results with a driver prototype verify the simulation results as well as dimmability.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2002년도 종합학술발표회 논문집 Vol.12 No.1
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• pp.241-245
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• 2002

Dual-band microstrip antenna is designed for industrial-scientific-medical(ISM) band of 2.4㎓ and 5.8㎓ using finite-difference time-domain method(FDTD). Cross Patch fed by aperture in the ground plane of microstrip line is proposed as radiation element of antenna, which is 2 rectangular Patch is overlapped. To design antenna, change of input impedance by aperture and stub length change is examined. And it is investigated that center frequency and -10 ㏈ bandwidth by Length of radiation element and width change. Experimental result about reflection Loss confirmed that agree well with analysis results of FDTD and IE3D, And -3 ㏈ beam width, front to back ratio and gain in frequency 2.43㎓ and 5.79㎓ is presented by measuring radiation Pattern of antenna.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2003년도 종합학술발표회 논문집 Vol.13 No.1
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• pp.454-458
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• 2003

It is well known that the antenna for wireless Tx/Rx isolation detector should have the broadband characteristics. Such antennas can be applied in all the frequency ranges such as Cellular, PCS, IMT-2000. In this paper, using the Finite-Difference Time-Domain(FDTD) method, one design example is given for the antenna operating in the frequency ranges of $800MHz{\sim}900 MHz$, $1.7GHz{\sim}2.2GHz$.

• 한국군사과학기술학회지
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• 제5권1호
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• pp.75-82
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• 2002

In this paper, the robust PID(Proportional-Integral-Derivative) controller was designed for speed control of BLDC motors using the frequency region model matching method. It was designed the robust PID controller satisfying disturbance attenuation and robust tracking performance using an H$\infty$ control method. The robust PID controller gains with the performances of the designed H$\infty$ controller are determined using the model matching method at frequency domain. Consequently, simulation results show that the proposed PID speed controller satisfies load torque disturbance attenuation and robust tracking performance, and this study has usefulness and applicability for the speed control system design of BLDC motors.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 D
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• pp.1803-1804
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• 2006

The purpose of this paper is to implement a Labview based TFDR Real Time system through the instruments of Pci eXtensions for Instrumentation(PXI). The proposed load impedance measurement algorithm was verified by experiments via the implemented real time system. The TFDR real time system consisted of the reference signal design, signal generation, signal acquisition, algorithm execution and results display parts. To implement real time system, all of the parts wore programmed by the Labview which is one of graphical programming languages. In the application software implemented by the Labview we were able to design a suitable reference signal according to the length and frequency attenuation characteristics of the target cable and controled the arbitrary waveform generator(ZT500PXI) of the signal generation part and the digital storage oscilloscope(ZT430PXI) of the signal acquisition part. By using the TFDR real time system with the terminal resistor on the target cable, we applied to the load impedance measurements. In the proposed load impedance algorithm a normalized time-frequency cross correlation function and a cross time-frequency distribution function was employed to calculate the reflection coefficient and phase difference between the input and the reflected signals.

• 한국음향학회지
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• 제29권5호
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• pp.339-346
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• 2010

음향 간섭제거기는 머리전달함수 (head-related impulse response; HRIR)의 길이에 큰 영향을 받게 되어, 일반적으로 큰 차수의 필터를 필요로 한다. 간섭제거필터의 길이를 줄이기 위한 방법으로 주파수 워핑, 공통 극점과 영점 (common acoustical pole and zero; CAPZ) 모델링 등의 방법들이 제안되었는데, 본 논문에서는 이 두 가지 방법을 결합한 방법을 제안한다. 이를 위해, 주파수 워핑 영역에서 공통 극점과 영점 모델링을 통해 필터를 설계하며, 디워핑 과정을 통해 종래의 선형 영역에서 안정된 필터를 구현한다. 제안된 방법은 주파수 워핑을 통한 간섭제거 성능 향상과 공통 극점 모델링을 통한 필터 계수 감소를 함께 제공할 수 있다. 이러한 성능을 검증하기 위해 다양한 컴퓨터 모의 실험을 진행하였다.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2008년도 춘계종합학술대회 A
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• pp.213-217
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• 2008

본 논문에서는 표준 IMC-PID 제어기에 시스템 식별상의 위상 조절 인자를 설계 변수로 추가함으로 새로운 IMC-PID 제어기 설계 방법을 제안한다. 제안된 제어기의 동조법으로 해석적으로 구해진 주파수 영역 특성을 통해 주파수 영역 성능을 보장하도록 하는 설계 변수의 구속 조건 하에서 시간영역의 적분 오차 지표를 가격함수로 최소화하는 최적 해를 얻는다. 이 제안된 동조법은 다양한 설계 사양을 동시에 고려하도록 하여 기존의 IMC-PID의 단일 설계 변수 동조가 갖는 비유연성 문제를 개선하였다. 사례 연구에서 기존의 동조법들과의 성능 비교를 통해 그 유용성을 검토했다.

• Nuclear Engineering and Technology
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• 제55권5호
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• pp.1577-1586
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• 2023

Safety qualification of a steam generator is a crucial issue related to faulted condition design loads, including earthquake loads, and it should be ensured that the structural integrity of a steam generator does not exceed its design load. Using data from the Gyeongju and Pohang earthquakes, the two most powerful recorded seismic events in Korea, seismic analyses of a typical steam generator are conducted in this study. The modal characteristics are used to develop an input deck for these analyses. With a time history analysis, the responses of the steam generator in the event of an earthquake are obtained. In particular, the displacement, velocity, and acceleration responses are obtained in the time domain, with these outcomes then used for a detailed structural analysis as part of the ensuing assessment. The response spectra are also generated to determine the response characteristics in the frequency domain, focusing on the response comparisons between the Gyeongju and Pohang earthquakes. Structural integrity can be ensured by performing additional analysis using results obtained from the time history analysis considering the input excitations of various earthquakes considered in the design.

• 융합정보논문지
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• 제10권7호
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• pp.131-137
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• 2020

가진 정현파 강제력에 의한 강제 진동의 특성이 연구되었고 또한, 주파수 영역에서 FRF의 수치 분석을 자세히 수행하였다. 이와 관련하여 강제 진동 모델에서 변위, 속도 및 가속도의 응답을 구하였다. 고유 주파수 주변의 실수부와 허수부의 FRF 특성도 각 경우에 따라 구하였다. 시간 영역에서의 강제 진동의 응답분석은 정현파 강제 진동의 특성을 식별할 수 있다. 변위, 속도 및 가속도 등의 응답을 얻기 위해 Runge-Kutta-Gill 방법의 수치해석 기법을 수행하여 강제력 주파수에 따른 응답을 얻었고 이 주파수는 응답에 큰 영향을 미치지 않았다. 또한, FRF는 강제 진동의 고유 특성을 나타내고 있으며 이러한 강제 진동 모델의 각 감쇠 조건에서 이러한 응답분석을 성공적으로 자세하게 얻을 수 있었다. 상이한 질량, 감쇠 및 강성에 대한 수치 분석 후, 정현파 강제력에 의한 강제 진동 응답 특성을 강제력의 진폭 및 주파수를 동시에 고려하여 분석되었다.

• 동력기계공학회지
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• 제17권3호
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• pp.72-81
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• 2013

Many articles have been published about a 2-degree of freedom model that includes the lateral and yaw motions for controller synthesis in intelligent transport system applications. In this paper, a 3-degree of freedom linear model that includes the roll motion is developed to design a robust steering controller for lane following maneuvers using ${\mu}$-synthesis. This linear perturbed system includes a set of parametric uncertainties in cornering stiffness and unmodelled dynamics in steering actuators. The state-space model with parametric uncertainties is represented in linear fractional transformation form. Design purpose can be obtained by properly choosing the frequency dependent weighting functions. The objective of this study is to keep the tracking error and steering input energy small in the presence of variations of the cornering stiffness coefficients. Furthermore, good ride quality has to be achieved against these uncertainties. Frequency-domain analyses and time-domain numerical simulations are carried out in order to evaluate these performance specifications of a given vehicle system. Finally, the simulation results indicate that the proposed robust controller achieves good performance over a wide range of uncertainty for the given maneuvers.