김래영 교수

The analysis and design of an adaptive maximum power point tracking (MPPT) scheme using incremental impedance are presented. A small-signal model is mathematically derived, and the impact of two major design parameters, which are scaling factor and sampling interval, is analyzed in the frequency domain. Four factors which specifically affect the MPPT response are also clearly addressed. Based on this analysis, a design methodology to achieve a desirable transient response, while retaining system

A boost-cascaded-with-buck converter-based power conditioning system employing a seamless mode transfer maximum power point tracking controller is proposed to maximize energy production of a thermoelectric generator while balancing a vehicle battery, alternator output power, and vehicle load. When a vehicle battery is fully charged, the proposed controller switches to a power matching mode seamlessly by a dual loop control system, which detects the input and output voltages and currents of the b

This paper proposes a new instantaneous power control method using the rotating frame with an all pass filter for a single-phase grid tie inverter. The recently proposed single-phase rotating frame is reanalyzed based on the phasor notation that has been widely used to understand linear electrical circuits and then the relationship between them is defined. A grid tie inverter circuit model with a LCL filter is derived in a single-phase rotating frame. A novel average power control method with an

Neuroelectronic interfaces are imperative in investigating neural tissues as electrical signals are the main information carriers in the nervous system and metal microelectrodes have been widely used for recording and stimulation of nerve cells. For high performance microelectrodes, low tissue-electrode interfacial impedance and high charge injection limits are essential and nanoscale surface engineering has been utilized to meet the requirements for microelectrodes. We report a single-cell size

PURPOSE: To evaluate choroidal vascular structure in eyes with central serous chorioretinopathy (CSC) by assessing the choroidal vascular index (CVI). METHODS: We retrospectively analyzed the medical records of 117 eyes with CSC. Subjects were divided into 4 groups according to clinical characteristics: 1) acute CSC (N = 29), 2) non-neovascularized chronic CSC without flat irregular pigment epithelial detachment (N = 49), 3) non-neovascularized chronic CSC with flat irregular pigment epithelial

For a wide output voltage ranged thermoelectric generator, it is necessary to have a dc-dc converter that allows voltage boost and buck functions. In this paper, a boost-buck cascade dc-dc converter is adopted to allow input voltage range from near 0 V to 25 V and output voltage range from 12.3 V to 16.5 V, needed for vehicle battery charging. To ensure a smooth operating mode change, a modified maximum power point tracking controller is used to control the first stage converter duty cycle while

국내 소규모 쌀 가공 산업현장에서 적용될 수 있는 쌀가루의 습식제분방법을 모색하고자 수침시간(3, 6, 9 및 12 hr)을 달리한 세 가지 제분방법에 의해 제조된 쌀가루의 이화학적 특성을 비교분석하였다. 사용된 제분방법은 roller mill, pin mill 그리고 roller & pin mills 등 세 가지이다. 모든 제분기에서 수침시간이 증가할수록 미세입도 분포율이 상승하였다. 쌀가루의 미세 정도는 roller mill의 쌀가루가 가장 거칠었고 roller & pin mills는 중간정도, pin mill의 쌀가루가 가장 미세하였다. 조단백질, 조지방, 조회분은 수침시간 증가에 따라 감소하였다. 조단백질 함량은 pin mill 9, 12시간 수침에서 각각 7.66%와 7.58%로 낮게 나타났다. 수침시간 증가에 따라 L값은 증가하였고, a, b값은 감소하였다. 손상전분은 수침초기 roller mill에서 낮았으나 수침시간이 증가하면서 pin mill이 낮아져 수침 12시간에

OBJECTIVE: Platinum black (PtBK) has long been used for microelectrode fabrication owing to its high recording performance of neural signals. The porous structure of PtBK enlarges the surface area and lowers the impedance, which results in background noise reduction. However, the brittleness of PtBK has been a problem in practice. In this work, we report mechanically stable PtBK microelectrodes using a bioinspired adhesive film, polydopamine (pDA), while maintaining the low impedance of PtBK. AP

A device suitability analysis is performed herein by comparing the performance of a silicon carbide (SiC) metal-oxide-semiconductor-field-effect transistor (MOSFET) and a gallium nitride (GaN) high-electron mobility transistor (HEMT), which are wide-bandgap (WBG) power semiconductor devices in induction heating (IH) systems. The WBG device presents advantages such as high-speed switching owing to its excellent physical properties, and when it is applied to the IH system, a high output power can

A photovoltaic array exhibits several local and single global maximum power points under partial shading conditions. To track the global maximum power point precisely, a novel global maximum power point tracking scheme is proposed in this paper. In the proposed scheme, robustness of the tracking performance has been improved by enhancing searching profile. In addition, the paper addresses the tracking failure condition, and provides the experimental verification with several simulation and exper