• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 연구회 합동 학술발표회 논문집
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• pp.18-22
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• 1998

A PWM inverter with an induction motor often has a problem with a high frequency leakage current that flows through stray capacitor between stator windings and a motor frame to ground. This paper presents an equivalent circuit for high frequency leakage currents in PWM inverter feeding an induction motor, which forms an LCR series resonant circuit. A conventional common mode ckoke or reactor in series between the ac terminals of a PWM inverter and those of an ac motor is not effective to reduce the rms and average values of the leakage current, but effective to reduce the peak value. Furthermore, this paper proposes a leakage current damper which is different in damping principle from the conventional common mode choke. It is shown theoretically and experimentally that the leakage current damper is able to reduce the rms value of the leakage current to 25%, where the core used in the leakage current damper is smaller than that of the conventional common-mode choke

• E2M - 전기 전자와 첨단 소재
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• 제3권2호
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• pp.123-130
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• 1990

본 논문은 페라이트의 온도특성을 측정하기 위한 다중측정시스템의 설계에 관하여 연구한 것이다. 본 시스템은 전기로의 온도를 제어하기 위한 열전대 콘트롤러, 릴레이 동작을 제어하기 위한 릴레이 콘트롤러 및 릴레이를 구동시키기 위한 스윗칭부, 그리고 GPIB를 이용한 LCR메터 제어부와 이들을 마이크로 컴퓨터와 통신하기 버스 라인으로 구성하였다. 열전대 콘트롤러와 릴레이 콘트롤러는 8255A(Intel LSI)를 주로 이용하여 설계하였으며 릴레이로는 고주파용 릴레이를 사용하여 스윗칭 트랜지스터로 구동시키는 방법을 택하였다. 그리고 LCR-메터에는 GPIB(AD50488)보드를 사용하였다. 측정시료로서는 복합첨가제방식에 의하여 제작된 Mn-Zn-Fe계 페라이트의 시편을 사용하였으며 시료의 특성측정은 자체 제작한 자동계측시스템을 이용하여 분석하였다. 측정결과 온도보상점 T$_{o}$ 와 큐리온도 T$_{c}$ 바로 아래에서 투자율의 급격한 변화를 확인할 수 있었다. 그리고 특성의 계측에 있어서 일관성이 있고 정확한 자료를 얻을 수 있었으며 따라서 본 시스템이 인터페이스와 컴퓨터 사이의 연결성이 좋은 자동다중계측시스템으로 활용 할 수 있음을 확인한다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.234-234
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• 2008

Chemically homogeneous $Ba_{0.6}Sr_{0.4}TiO_3$ (BST) sols were synthesized using barium acetate, strontium acetate, and titanium isoproxide as starting materials. BST thin films of thickness 340 nm were deposited on Pt/$TiO_2/SiO_2$/Si and alumina substrates using spin coating method. The technique used for the processing of these films was Ultraviolet (UV) sol-gel photoannealing, using phto-sensitivity precursor solutions and UV-assisted rapid thermal processing(UV-RTP). The crystallization behaviour of the BST sols and thin films was studied by differential thermal analysis (DTA) and X-ray diffraction (XRD). Variation of permittivity and dielectric loss were measured in LCR-meter, model HP 4394A.

• 전기학회논문지P
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• 제57권3호
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• pp.279-284
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• 2008

We have developed two absolute evaluation technology of inductor using current transformer (CT) comparator. One is the method that the reactance of inductor is obtained by analysing the equivalent circuit of CT with inductor connected to series at secondary terminal of CT. The other is the method that the reactance of inductor is obtained by comparing phase displacement of current flowing on inductor by using CT comparator. These technologies have the advantage to apply up to rated current and voltage of inductor. The method was applied to inductors under test in the range of $100 {\mu}H{\sim}1\;H$. The inductance of the inductor under test obtained in this study are consistent with those measured by LCR meter using the same inductor within an expanded uncertainty (k = 2) in the overall range of inductance.

• 전기학회논문지P
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• 제57권3호
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• pp.285-290
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• 2008

We have developed the absolute evaluation technique of capacitor and inductor by measuring the phase displacement as a function of resistance of employed resistors in voltage transformer(VT) comparator. The methods were applied to the capacitor with the range of 100 nF - $5{\mu}F$ and the inductor with the range of $100{\mu}H{\sim}1\;H$. The capacitance values of capacitor obtained using our method are consistent within the expanded uncertainty those obtained using capacitor bridge. The inductance values of inductor obtained using our method are also consistent within the expanded uncertainty those obtained using LCR meter.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2015년도 제46회 하계학술대회
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• pp.992-993
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• 2015

본 논문은 양방향 전류 제어를 위한 고안정 전류원 전원 장치의 영점 전류 부근에서의 PWM 방법과 출력 필터 설계를 위한 가이드 라인에 대해 기술 하였다. LCR 출력 필터의 공진점에서 전압의 크기를 줄이기 위한 댐핑 저항의 크기에 따라 Bode plot을 통해 임피던스와 전달함수의 주파수 특성을 분석하고 낮은 Q-factor를 갖는 출력 필터의 댐핑 저항 크기를 확인 하였다.

• Korean Journal of Mathematics
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• 제16권4호
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• pp.553-564
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• 2008

We have a concern with the existence of solutions (${\xi},{\eta}$) for perturbations of the parabolic system with Dirichlet boundary condition $$(0.1)\;\begin{array}{lcr}{\xi}_t=-L{\xi}+{\mu}g(3{\xi}+{\eta})-s{\phi}_1-h_1(x,t)\;in\;{\Omega}{\times}(0,2{\pi}),\\{\eta}_t=-L{\eta}+{\nu}g(3{\xi}+{\eta})-s{\phi}_1-h_2(x,t)\;in\;{\Omega}{\times}(0,2{\pi})\end{array}.$$ We prove the uniqueness theorem when the nonlinearity does not cross eigenvalues. We also investigate multiple solutions (${\xi}(x,t),\;{\eta}(x,t)$) for perturbations of the parabolic system with Dirichlet boundary condition when the nonlinearity f' is bounded and $f^{\prime}(-{\infty})<{\lambda}_1,{\lambda}_n<(3{\mu}+{\nu})f^{\prime}(+{\infty})<{\lambda}_{n+1}$.

• Journal of Communications and Networks
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• 제5권3호
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• pp.197-201
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• 2003

We study in this paper both distributed power control and removal algorithms for multimedia CDMA wireless networks. In our study, users can have different data rates as well as different quality of service (QoS) requirements. We derive a necessary and sufficient condition for the fully distributed power control (FDPC) algorithm to find a feasible power set. We also prove that, if the maximal power level is used at the start, then the distributed constrained power control (DCPC) algorithm is equivalent to the FDPC algorithm. For the connection removal algorithm, we prove that the non-reinitialized removal algorithm finds a feasible power set faster and employs smaller power levels than the reinitialized one does. Performances of some connection removal criteria are also studied. Our simulation results reveal that the smallest normalized CIR (SNC) and largest CIR requirement (LCR) criteria result in smaller outage probability than the smallest CIR (SC) criterion in a multimedia environment.

• Journal of Magnetics
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• 제13권4호
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• pp.177-181
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• 2008

A very simple a.c. magnetic susceptometer for use in a helium closed cycle cryostat is reported in this paper. This simple setup has only a single bobbin-less copper coil, instead of the primary coil and two secondary coils typically used in mutual-inductance types. The single bobbin-less copper coil is directly mounted on the cryostat cold head. A sample is attached on the inside wall of the copper coil using a thermal contact material and its a.c. magnetic susceptibility is obtained from the measurement of the self-inductance of the sample coil using an LCR meter or an impedance analyzer. Experimental details are described and illustrative measurements on magnetic and superconducting materials as a function of temperature are included. The performances and limitations of this simple a.c. magnetic suceptometer are also discussed.

• 한국반도체및디스플레이장비학회:학술대회논문집
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• 한국반도체및디스플레이장비학회 2006년도 춘계학술대회
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• pp.131-134
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• 2006

ITO/ polytetrafluorethylene (PTFE)/ Tris(8-hydroxyquinolinato Aluminum ($Alq_3$)/ Al 구조에서 정공 주입층 PTFE 의 두께 변화에 따른 유전특성은 HP 4284A precision LCR Meter 를 이용하여 주파수에 따른 임피던스와 위상각, 유전손실, 그리고 캐패시턴스를 측정하였다. 측정 결과 PTFE 의 두께가 증가할수록 임피던스 값은 증가하고, 위상각은 저주파수 영역에서는 두께가 증가할수록 감소하다가 고주파수 영역에서는 거의 같아지는 것을 확인하였다. 또한, 유전손실($tan{\delta}$)도 저주파수 영역에서는 정공 주입층이 증가할수록 감소하다가 고주파수 영역에서는 거의 같아졌고, 캐패시턴스는 PTFE 의 두께가 증가함에 따라 작아지고 주파수가 높아질수록 감소함을 확인하였다.