Kyung Hwan Lee

This paper presents a novel family of single-switch resonant dc-dc converters with low switch voltage stress. The single-switch resonant converter which has a ground-referenced switch is advantageous for implementing the gate drive circuit and operating at several-MHz switching frequency. However, the conventional ones mostly have high voltage stress on the switch, roughly 4-5 times the input voltage. In this paper, we propose the single-switch converter topologies derived from the drain-source

This paper proposes a resonant switching cell model to analyze and design the single-ended resonant dc-dc converters. The single-ended zero-voltage switching (ZVS) converters such as the Class E converter are efficient for megahertz switching because they feature low turn-on and turn-off switching losses. Also, they use only a ground-referenced switch, allowing a simple gate drive circuit. In this paper, we investigate the single-ended resonant converter with the small input inductance, whereas

In this paper, we analyzed the characteristics of dominant failure mechanisms in the erased (ERS) state of sub 20-nm NAND Flash memory with an accurate compact model. As a result, it was observed that various charge loss and charge gain mechanisms are mixed together. While the detrapping and the interface trap recovery (N <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">it</inf> ) mechanism contribute to the charge loss, the trap-assisted tunneling (

This paper proposes a novel design of class E dc-dc converter with a resonant rectifier circuit. Class E converter is advantageous in several-MHz switching since it achieves zero voltage switching (ZVS) and has the single ground-referenced switch. In this paper, the resonant rectifier is used to construct a dc-dc converter in conjunction with the class E inverter instead of the conventional rectifiers such as a half-wave rectifier and a full-wave bridge rectifier. The main benefit of the resonan

This paper presents an analysis and a novel design method of the resonant rectifier for dc-dc power converters operating in MHz frequency range. Compared to the conventional rectifier circuits such as a half-wave rectifier and a full-bridge one, the resonant rectifier features zero or low dv/dt at the turn-on and turn-off instant of the diode in the rectifier. Therefore, it significantly reduces undesirable oscillation of parasitic inductance and capacitance caused by high dv/dt and thereby prov

This paper presents a novel design method for class E dc-dc converter and a control scheme capable of operating in a wide load range. The class E converter is suitable for several-MHz switching frequency; however, the conventional design has two drawbacks: high voltage stress on the switch (theoretically about 3.6 times the input voltage), and a large input inductor. Here we propose the design scheme to reduce the peak switch voltage up to 2.2-2.5 times the input voltage without additional circu

Objective : The thyrotoxic periodic paralysis mainly appears in case of hyperthyroidism and the amyotonia is the characteristic main symptom. Through the deteriorated case and treatment by oriental medicine, the purpose of this research is to study the change of symptoms and the treatment effect for one case of a thyrotoxic periodic paralysis patient. Methods and Results : The treatment was carried out with oriental medicine as a main treatment and by the oriental medicinally deteriorated case,

The purpose of this study is to analyze compact city planning indicators that have influence on public transportation commuting of residents in the 54 medium and small-sized cities. In the study, land use and transportation infrastructure of cities and other socio-demographic variables are used as explanatory variables in a causal model. 96,552 subjects from 54 cities in korea are selected as the final sample, and a statistical analysis is carried out by applying Random Intercept Logit Model. An

This paper proposes a novel control scheme for minimizing the line loss of three-phase converters under unbalanced grid voltages. Most prior works focus on balancing phase currents or eliminating dc-link voltage ripples. However, they do not consider rms currents, so the efficiency may be lowered. In this paper, the optimal current reference is proposed to minimize sum of squares of rms currents in three lines. As a result of the proposed strategy, the efficiency of both converter itself and ove

The major issues of managing an organization and its environments are on how to establish a community for their co-survival and collaboration. This study is on the principles and management practices for establishing the community of organization and its environments based on the power circulatory approach, so that it contributes to creation of the social orders for co-survival and collaboration. In order to do this I discussed the theories and practices of the power circulatory approach, and th

In this paper, we propose and analyze an Adaptive Modulation System with optimal Turbo Coded V-BLAST (Vertical-Bell-lab Layered Space-Time) technique that adopts the extrinsic information from MAP (Maximum A Posteriori) Decoder with Iterative Decoding as a priori probability in two decoding procedure of V-BLAST scheme; the ordering and the slicing. Also, comparing with the Adaptive Modulation System using conventional Turbo Coded V-BLAST technique that is simply combined V-BLAST scheme with Turb