• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 추계학술대회 논문집
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• pp.301-305
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• 1996

$\mu$ theory can handle the parametric uncertainty and produces more non-conservative controller than H$_{\infty}$ control theory. However an existing solution of the theory, D-K iteration, creates a controller of huge order and cannot handle the real or mixed real-complex perturbation sets. In this paper, we use genetic algorithms to solve these problems of the D-K iteration method. The Youla parameterization is used to obtain all stabilizing controllers and the genetic algorithms determines the values of the state feedback gain, the observer gain, and Q parameter to minimize $\mu$, the structured singular value, of given system. From an example, we show that this method produces lower order controller which controls a real parameter-perturbed plant than D-K iteration method.

• 한국전자파학회논문지
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• 제11권3호
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• pp.445-453
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• 2000

본 논문에서는 MMlC 설계에서 필요한 능동 인덕터의 설계 방법을 제시하였다. 제안된 가변 능동 인덕터는 궤환 커패시터와 궤환 저항을 가진 종속접속된 2개의 FET로 구성을 하였다. 제안된 가변 능동 인덕터는 낮은 직렬 저항을 가져서 상대적으로 높은 Q 값을 얻을 수 있고 높은 주파수대에서 사용이 가능한 우수한 동작 특성 을 가진다. 인덕턴스 값은 궤환 커패시터와 궤환 저항 및 바이어스 전압에 의하여 변화되어지며 궤환 저항과 회 로내 병렬 저항을 가변하였을 때 1 GHz에서 15 GHz까지 범위에서 인덕턴스 값이 0.2nH에서 L7nH까지 변화하 였다. 또한 제안된 능동 인덕터를 사용하여 대역통과 필터를 설계하였을 때 삽입손실은 약 0.4 dB이고 반사 손실은 20dB 이상의 우수한 결과를 얻을 수 있었다

• Transactions on Electrical and Electronic Materials
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• 제13권6호
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• pp.283-286
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• 2012

(1-X)$(Na_{0.5}K_{0.5})NbO_3-XK_{5.4}Cu_{1.3}Ta_{10}O_{29}$ (NKN-KCT) lead-free piezoelectric ceramics have been synthesized by the conventional solid state sintering method, and their sinterability and piezoelectric properties were investigated. Typically, this material is sintered between 1,025 and $1,100^{\circ}C$ for 2 hours to achieve the required densification. Crystalline structures and Microstructures were analyzed by X-ray diffraction and scanning electron microscope. The density, dielectric constant (${\varepsilon}_r$), piezoelectric constant $d_{33}$, electromechanical coupling factor $k_p$ and mechanical quality factor $Q_m$ value of the NKN ceramics depended upon the KCT content and the sintering temperature. In particular, the KCT addition to NKN greatly improved the mechanical quality factor $Q_m$ value. The ceramic with X = 1.0 mol% sintered at $1,050^{\circ}C$ exhibited optimum properties (${\varepsilon}_r$=246, $d_{33}$=95, $k_p$=0.38 and $Q_m$=1,826). These results indicate that the ceramic is a promising candidate material for applications in lead free piezoelectric transformer and filter materials.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1999년도 전력전자학술대회 논문집
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• pp.252-255
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• 1999

A new dead-time compensation method using a disturbance observer is proposed. The dead-time causes the voltage distortion and it can be considered as the disturbance voltage. In this paper, the disturbance voltage is estimated by minimal order observer in the d-q frame and the estimated disturbance voltage is summed with voltage command by a feed-forward. The experiments are carried out for the DSP-based BLDC motor drive system and the results show the effectiveness of the proposed method.

• The Korean Journal of Ecology
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• 제23권4호
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• pp.315-321
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• 2000

The occurrence and distribution of Dictyostelid cellular slime molds on Mt. Mukak soils with two different vegetation types were investigated. Two plating methods were used for the isolation of dictyostelids following Dr. Hagiwara's method. Dictyostelium and Polysphondylium were isolated in these soils. D. purpureum (subtropical form ) and D. giganteum were observed in both Quercus variabilis and Pinus thunbergii communities soils. D. delicatum, B. sp-1 (D. brefeldianum complex). D. sp-2 (D. brefeldianum complex), D. minutum and P. pallidum complex occurred only in Q. variabilis soil. D. macrocephalum, D. purpureum (temperate form ), D. robustum, D. polycephalum, P. violaceum, and P. pallidium occurred only in P. thunbergii soil. P. pallidium complex is being identified.

• 전력전자학회논문지
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• 제5권2호
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• pp.123-129
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• 2000

본 논문은 실용화 보급단계에 있는 대표적인 대체에너지 전원으로서, 태양전지, 직·교류(DC/AC) 인버터, 전력계통으로 구성되는 계통연계형 태양광발전시스템의 설계 및 시험결과에 대하여 기술하고자 한다. 계통연계를 위한 시스템 특성을 검증하기 위해 3상 직·교류 인버터를 포함한 50kW 계통연계 태양광발전시스템이 설계 제작되었다. 또한 d-q 변환을 이용한 PI 제어기를 갖는 전류제어방식의 3상 PWM 인버터 제어기법이 제시되었다. 실험결과들은 제안된 시스템이 계통연계 동작에 있어서 단위 역율로 안정하게 동작함을 보여준다.

• 반도체디스플레이기술학회지
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• 제14권3호
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• pp.45-50
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• 2015

This paper suggests the sensor-less speed control of PMSM (Permanent Magnet Synchronous Motor) without the position sensor of oil-free air compressor. It estimated d and q axis back electro motive force using Back-EMF (Electro motive Force) observer to control sensor-less speed of PMSM. Also it used the method that tracks the information of rotor position and speed using PLL (Phase Locked Loop) based on estimated d and q axis Back-EMF. The sensor-less speed control of PMSM for oil air compressor application is carried out with the introduced rotor position and speed tracking method. In this paper, the experimental characterization of the sensor-less drive is provided to verify the accuracy of the estimated position and the performance of sensor-less control is analyzed by results obtained from the experiment. Moreover, the potential of PMSM sensor-less drive in industrial application such as compressor drive is also examined.

• 한국진공학회지
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• 제7권2호
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• pp.112-117
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• 1998

TiN을 Cu의 확산방지막으로 사용하기 위해 많은 연구가 되어왔는데, 이 연구에서는 특히 X-ray photoelectron spectroscopy(XPS)를 이용하여 TiN박막에서의 Cu의 확산현상을 연구하였다. TiN박막은 일반적으로 columnar grain을 형성하면서 성장을 하는데, 녹는점의 1/3에 해당하는 비교적 낮은 온도에서는 grain들의 경계를 따라 Cu가 확산함을 확인하였다. Atomic force microscopy(AFM)를 이용하여 grain의 모양을 관찰하였고, 이 grain boundary 를 통한 확산 현상을 연구하기 위하여, modified surface accumulation method를 이용하였 다. 연구 결과, TiN박막에서의 Cu의 grain boundary diffusion의 활성화 에너지 $Q_b$는 0.23 eV, Diffusivity $D_{bo}$는 $5.5\times10^{-12{\textrm{cm}^2$/sec의 값을 얻었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1988년도 추계학술대회 논문집 학회본부
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• pp.193-195
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• 1988

The native oxide films were thermally and anodically formed on the n-GaP substrates grown by SSD method and measured this oxide thickness and the chemical composition and the electrical properties with formation condition. The chemical composition of themally oxidized GaP film was composed of mostly $GaPO_4$ at temperature below $800^{\circ}C$ and mostly $\beta-Ga_{2}O_{3}$ above $800^{\circ}C$. But The chemical composition of anodically oxidized GaPfilm was composed of the mixture of $Ga_{2}O_{3}$ and $P_{2}O_{5}$. The barrier height of Al/oxide/n-Gap which was formed at $700^{\circ}C$ by thermal oxidation method were 1.10eV, 1.03eV in Current-Voltage measurement. Interface charge density were $4{\times}10^{12}q(C/cm^2)$ and $3{\times}10^{12}q(C/cm^2)$ in Capacitance-Voltage measurement respectively.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 A
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• pp.58-60
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• 1999

This paper presents dynamic performance prediction using Matlab / simulink after parameter estimation of synchronous reluctance motor considering iron loss. Test motor is 3 phase SynRM with the segmental rotor, rating power is 0.175KW. Experiment equipment is consists of testing motor, dynamometer, vector invertor dynamocontroller, and power analyser. The stator iron loss and rotor iron loss are modelled by additional windings on three-phase winding axis. These windings are transformed into d-q axis, and are represented as equivalent eddy current windings. P-Q circle diagram method and single phase standstill method are used to measure motor parameters considering iron loss.