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See-Hoon Jeong,Ju-Il Jin,Hwa-Pyeong Park,Jee-Hoon Jung 전력전자학회 2022 JOURNAL OF POWER ELECTRONICS Vol.22 No.6
Nowadays all-metal induction heating (IH) cooktops have become popular for heating various pots quickly and safely. A load adaptive modulation (LAM) method was proposed to improve the IH power delivery capability and the cost-eff ectiveness of an all-metal IH system. However, this method shows poor power conversion effi ciency under light-load conditions since a high switching loss is induced using the pulse frequency modulation (PFM) method in the series resonant inverters for IH applications. In this paper, a multi-mode control strategy for an IH system employing the LAM method is proposed to improve light-load effi ciency when compared with the conventional LAM method. The proposed multi-mode control algorithm automatically changes its modulation according to the pots’ material-dependent resistance. The modulation method is selected to improve the light-load effi ciency using the proposed control strategy. Experimental results demonstrate the validity and performance of the proposed multi-mode control algorithm with a 2-kW prototype IH series resonant inverter and various-material pots.
Analytic solutions for variance swaps with double-mean-reverting volatility
Kim, See-Woo,Kim, Jeong-Hoon Elsevier 2018 Chaos, solitons, and fractals Vol.114 No.-
<P><B>Abstract</B></P> <P>A three factor variance model introduced by Gatheral in 2008, called the double mean reverting (DMR) model, is well-known to reflect the empirical dynamics of the variance and prices of options on both SPX and VIX consistently with the market. One drawback of the DMR model is that calibration may not be easy as no closed form solution for European options exists, not like the Heston model. In this paper, we still use the double mean reverting nature to extend the Heston model and study the pricing of variance swaps given by simple returns in discrete sampling times. The constant mean level of Heston’s stochastic volatility is extended to a slowly varying process which is specified in two different ways in terms of the Ornstein-Uhlenbeck (OU) and Cox-Ingersoll-Ross (CIR) processes. So, two types of double mean reversion are considered and the corresponding models are called the double mean reverting Heston-OU model and the double mean reverting Heston-CIR models. We solve Riccati type nonlinear equations and derive closed form exact solutions or closed form approximations of the fair strike prices of the variance swaps depending on the correlation structure of the three factors. We verify the accuracy of our analytic solutions by comparing with values computed by Monte Carlo simulation. The impact of the double mean reverting formulation on the fair strike prices of the variance swaps are also scrutinized in the paper.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Double-mean-reverting volatility is considered for variance swaps. </LI> <LI> We obtain closed form exact solutions or approximations. </LI> <LI> The characteristic function is exploited to derive the prices. </LI> <LI> Numerical tests show the validity and sensitivity of the prices. </LI> </UL> </P>
Lee, See Hoon,Lee, Tae Hee,Jeong, Sang Mun,Lee, Jong Min Pergamon 2019 RENEWABLE ENERGY Vol.138 No.-
<P><B>Abstract</B></P> <P>In recent years, circulating fluidized bed combustor (CFBC) has been regarded as a viable alternative to the conventional pulverized coal combustor (PCC) for utility-scale coal power generation owing to its superior technology for fuel flexibility and supercritical (SC)/ultra supercritical (USC) steam circuit adaptability. The objective of this study is to analyze the economic feasibility of a 600MWe USC CFB boiler, in which coal or a mixture of coal and biomass would be used as fuel. After the demonstration and commercialization of SC CFBC units had succeeded up to 600MWe, USC CFBCs have been widely developed throughout the world. Although high capital costs, high auxiliary power use, and technology maturity have hindered the adoption of USC CFBC for utility power generation, the demand of cleaner environments and energy conversion have driven communities to develop and adopt USC CFBC. Its economic feasibility was evaluated in terms of net present value (NPV), benefit/cost ratio (B/C ratio), and internal rate of return (IRR). In particular, the effect of coal tax and domestic biomass co-combustion on economic efficiency was analyzed.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The economic feasibility of 600MWe USC CFB power plant were investigated. </LI> <LI> The economic efficiency of biomass co-combustion could be higher than that of coal combustion due to carbon trade exchange. </LI> <LI> The 600MWe USC CFB power plant with biomass co-combustion could be feasible in spite of coal tax or carbon tax. </LI> </UL> </P>