• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.538-540
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• 2008

본 논문은 조명용 RGB LED 구동 장치를 위한 새로운 방식의 Two-stage RGB LED 구동 회로를 제안한다. 제안된 회로는 PFC Flyback Converter의 다중 출력을 이용하여 LED 구동 회로의 전압 스트레스를 줄이면서 효율을 높일 수 있는 새로운 방식의 LED 구동회로이다. 제안된 회로는 Universal Input에서 25W 이상 조명 장치에 적용되는 IEC61000-3-2 Class C 규제를 만족하며, RGB LED의 개별적인 Digital Dimming을 사용하여 다양한 색을 구현할 수 있다. 본 논문에서는 제안된 회로의 동작 원리를 설명하고, 시뮬레이션 및 RGB LED에 실제 적용 실험하여 제안 회로의 유용성을 입증하였다.

• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.283-285
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• 2008

본 논문은 조명용 LED 구동 장치를 위한 새로운 방식의 Two-stage LED 구동 회로를 제안한다. 제안된 회로는 PFC Flyback 회로의 다중 출력을 이용하여 LED 구동 회로에 사용된 소자의 내압 저하가 가능하고, 기존의 Two-stage LED 구동 회로에 비해 높은 효율을 갖는다. 제안된 회로는 Universal Input에서 25W 이상 조명 장치에 적용되는 IEC61000-3-2 Class C 규제를 만족하고, Digital Dimming을 사용하여 넓은 범위의 휘도 조절이 가능하다. 본 논문에서는 제안 회로의 동작 원리를 설명하고, 시뮬레이션 및 LED에 실제 적용 실험하여 제안 회로의 유용성을 입증하였다.

• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.693-696
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• 2005

We propose a robust adaptive fuzzy controller for the transient stability and voltage regulation of a single-machine inflnite bus power system. The proposed control scheme is based on the input-output linearization to eliminate the system nonlinearities. To deal with uncertainties due to a parameter variation or a fault, we introduce fuzzy systems with universal function approximating capability which estimate the uncertainties on-line.

• Proceedings of the KIPE Conference
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• 2013.07a
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• pp.337-338
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• 2013

Combination the several type of single phase power conversion utilized simply topology are proposed in this paper. Totally four kind of converter are investigated, they are Boost AC/AC Converter, Buck AC/AC Converter, Boost AC/DC Converter, and Buck DC/AC Converter. Two types action mode are presented to determine the functional of circuit. First is AC chopper action mode, representation of the AC/AC converter. AC chopper action mode offered the sinusoidal current waveform, better power factor, faster dynamics, and smaller input/output filter. They present high robustness, offer safe commutation and have high efficiency. The second is full bridge action mode, determined the transformation AC to DC power and otherwise. Four switching devices and one magnetic contactor will establish the mode operation of circuit and manage the flow of power proceed in proper. The correction and advance of the kind of converter are verified by simulation.

• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.162-163
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• 2017

본 논문에서는, 유니버셜 입력 전압에서 높은 효율을 가지는 새로운 구조의 브리지리스 부스트 PFC 컨버터를 제안한다. 제안하는 컨버터는 두 개의 인덕터와 네 개의 GaN 스위치, 두 개의 다이오드와 SPDT 릴레이를 사용하여 입력 전압에 따라 토폴로지 변환이 가능하다. 로우라인 입력전압이 인가될 경우, 제안하는 컨버터는 기존의 인터리브드 토템폴 브리지리스 PFC 컨버터로 동작하는 반면, 하이라인 입력전압이 인가될 경우, 제안하는 컨버터는 하나의 부스트 컨버터로 동작하게 된다. 따라서 제안하는 컨버터는 유니버셜 입력전압에서 높은 효율을 가지며, 고효율을 요구하는 서버용 전원장치나 유니버셜 입력을 요구하는 기타 PFC 어플리케이션에 적용될 수 있다. 제안하는 컨버터는 유니버셜 라인 입력 ($90V_{AC}{\sim}265V_{AC}$), 400V / 1.6kW 출력의 프로토타입 컨버터를 통해 동작을 검증하였다.

• Current Optics and Photonics
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• v.6 no.1
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• pp.15-22
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• 2022

This paper describes the construction of a phase shifter with low loss and small volume. To construct it, we use the two graphene layers that are separated by a hexagonal boron nitride (hBN) and embedded in a silicon waveguide. The refractive index of the waveguide is adjusted by applying a bias voltage to the graphene sheet to create an optical phase shift. This waveguide is a compact device that only has a radius of 5 ㎛. It has a phase shift of 6π. In addition, the extinction ratio (ER) is 11.6 dB and the insertion loss (IL) is 0.031 dB. Due to its unique characteristics, this device has great potential in silicon on-chip optical interconnection and all-optical multiple-input multiple-output processing.

• Proceedings of the KIPE Conference
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• 2020.08a
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• pp.112-114
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• 2020

기존 위상천이 풀브리지 컨버터는 입력전압 범위가 넓을 경우, 제어변수인 듀티의 변동이 크게 되어 큰 순환전류가 존재하고, 2차측 정류단 전압스트레스가 커지는 문제가 있다. 이러한 문제점을 해결하기 위해 본 논문에서는 위상천이 방식을 적용한 3-레그 인버터 타입의 절연형 컨버터를 제안한다. 제안회로는 턴 비의 변화로 입력전압에 상관없이 항상 최대 듀티로 동작하며, 1차측 전류 및 2차측 정류단 전압스트레스를 감소시킬 수 있다. 제안 회로의 타당성을 검증하기 위해, 입력 311V_DC/622V_DC, 출력 50V 6kW급 사양의 프로토타입 컨버터를 설계·제작하였고, 그 실험 결과를 발표한다.

• Smart Structures and Systems
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• v.23 no.6
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• pp.565-577
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• 2019

One of the most effective countermeasures for mitigating cable vibration is to install mechanical dampers near the anchorage of the cable. Most of the dampers used in the field are so-called passive dampers where their parameters cannot be changed once designed. The parameters of passive dampers are usually determined based on the optimal damper force obtained from the universal design curve for linear dampers, which will provide a maximum additional damping for the cable. As the optimal damper force is chosen based on a predetermined principal vibration mode, passive dampers will be most effective if cable undergoes single-mode vibration where the vibration mode is the same as the principal mode used in the design. However, in the actual engineering practice, multi-mode vibrations are often observed for cables. Therefore, it is desirable to have dampers that can suppress different modes of cable vibrations simultaneously. In this paper, MR dampers are proposed for controlling multi-mode cable vibrations, because of its ability to change parameters and its adaptability of active control without inquiring large power resources. Although the highly nonlinear feature of the MR material leads to a relatively complex representation of its mathematical model, effective control strategies can still be derived for suppressing multi-mode cable vibrations based on nonlinear modelling, as proposed in this paper. Firstly, the nonlinear Bouc-wen model is employed to accurately portray the salient characteristics of the MR damper. Then, the desired optimal damper force is determined from the universal design curve of friction dampers. Finally, the input voltage (current) of MR damper corresponding to the desired optimal damper force is calculated from the nonlinear Bouc-wen model of the damper using a piecewise linear interpolation scheme. Numerical simulations are carried out to validate the effectiveness of the proposed control algorithm for mitigating multi-mode cable vibrations induced by different external excitations.

• The Transactions of the Korean Institute of Power Electronics
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• v.16 no.4
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• pp.382-395
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• 2011

In this paper, for adapter with power level below approximately 60W, a novel LLC resonant converter preceded by diode rectifier with a capacitor filter is presented. Due to the switching operation of the auxiliary switching device, the proposed LLC resonant converter can deliver power with the high efficiency characteristics from the universal line($110V_{AC}$/ $220V_{AC}$) and load conditions. The operating schemes on the proposed converter are analyzed and described. A 60W prototype product is built, tested and verified.