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International Journal of Information Security - Machine learning techniques have been widely used and shown remarkable performance in various fields. Along with the widespread utilization of... 相似文献
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Jae Hyeok Park Chang-Ha Lee Young Cheol Park Dowon Shun Dal-Hee Bae Jaehyeon Park 《Drying Technology》2014,32(3):268-278
This research explores the production of low-moisture, high-rank coal using a batch-type, laboratory-scale, circulating fluidized bed to dry low-rank Indonesian coal with a high moisture content of 35 wt%. The operation was performed using air as a fluidization gas in a riser (a 4-m-tall pipe with an inner diameter of 0.04 m) at a gas velocity ranging from 2.0 to 2.7 m/s and a riser temperature of 80 to 150°C. The electric heaters were installed in the upper part of a downcomer to prevent the condensation of the evaporated moist- ure. The drying rate of the coal was investigated in terms of the inlet gas temperature, the gas velocity, and the drying time in order to determine the optimum operating conditions. Changes in the moist- ure content of the coal, before and after the experiments, were char- acterized by a proximate analysis, an ultimate analysis, the higher heating value (HHV), the lower heating value (LHV), a particle size analysis, and by the equilibrium moisture content. The results show that 70 to 80 wt% (wet basis, wb) of the total moisture can be reduced when the gas velocity of the riser is 2.0 m/s and the gas temperature is 150°C. In experiments, a simple mathematical model based on the heat and mass balances and a thin-layer drying model were simul- taneously used to predict the drying behavior of coal under the given operating conditions. The results of the model are similar to those of the experiment. 相似文献
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Seungchan Cho Kenta Takagi Hansang Kwon Dowon Seo Kazuhiro Ogawa Keiko Kikuchi Akira Kawasaki 《Surface & coatings technology》2012
Multi-walled carbon nanotube (MWCNT)-reinforced copper (Cu) nanocomposite coatings were successfully deposited on aluminum (Al) substrate by a cold spraying process at a low pressure. The microstructure and the Raman spectrum of the low-pressure-cold-sprayed MWCNT–Cu nanocomposite coating showed that the MWCNTs maintained their tube structure in the Cu matrix, even though structural damage to the MWCNTs increased slightly. MWCNT–Cu nanocomposite-coated Al exhibits higher thermal diffusivity than pure-Cu-coated Al with a comparable hardness. The higher thermal diffusivity of the MWCNT–Cu coating could be explained by the dispersion of MWCNTs within the clean and closed CNT/Cu interfaces, which were achieved with the aid of compressive stress during the cold spraying. 相似文献
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Byun et al. suggested keyword guessing attacks and showed that some PEKS (public-key encryption with keyword search) schemes are not secure to keyword guessing attacks, when the number of possible keywords is bounded by some polynomial. Abdalla et al. showed that robust PEKS schemes should satisfy consistency which ensures the PEKS schemes fulfil their functions. In the paper, we show a negative result about the open problem to construct secure PEKS schemes against keyword guessing attacks. Our result shows that consistency implies insecurity to keyword guessing attacks in PEKS. This means that constructing secure and consistent PEKS schemes against keyword guessing attacks is impossible, when the number of possible keywords is bounded by some polynomial. 相似文献
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Jae Hyeok Park Chang-Ha Lee Ji Bong Joo Dal-Hee Bae Dowon Shun Jong-Ho Moon 《Drying Technology》2016,34(9):1095-1106
Upgrading low-rank coal (LRC) through various strategies is always an important issue. Here, we report the production of hybrid coals and an evaluation of their characteristics for use as a fuel in power plants. The hybrid coals (HCKs) were prepared by a combination of drying and biomass impregnation into an Indonesian LRC followed by a precarbonization process. We used a top-spray fluidized-bed reactor for drying, biomass impregnation, and precarbonization to produce hybrid coals that have improved fuel characteristics in terms of heating value, moisture readsorption, and combustion patterns. A systematic study reveals that experimental parameters, such as a bed temperature, bioliquid spraying procedure, and precarbonization temperature strongly influence the characteristics of the resulting hybrid coal, meaning that they have an important role in upgrading LRC. In particular, the hybrid coal prepared by a process of simultaneous drying and bioliquid spraying followed by precarbonization at 200–300°C showed high contents of fixed carbon, an improved heating value, lower moisture adsorption, and single combustion patterns in which the characteristics were dramatically upgraded for practical use as a fuel in power plants. In addition, the simultaneous process using a fluidized-bed reactor has great potential because it can achieve process simplification, reduce manufacturing costs, and handle coal particles easily. 相似文献
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Subquadratic space complexity multipliers for optimal normal bases (ONBs) have been proposed for practical applications. However, for the Gaussian normal basis (GNB) of type t > 2 as well as the normal basis (NB), there is no known subquadratic space complexity multiplier. In this paper, we propose the first subquadratic space complexity multipliers for the type 4 GNB. The idea is based on the fact that the finite field GF(2n) with the type 4 GNB can be embedded into fields with an ONB. 相似文献
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The rotation‐based transformation (RBT) for privacy preserving data mining is vulnerable to the independent component analysis (ICA) attack. This paper introduces a modified multiple‐rotation‐based transformation technique for special mining applications, mitigating the ICA attack while maintaining the advantages of the RBT. 相似文献
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Dowon Shun Hyo Sup Chang Yeong Seong Park Dal-Hee Bae Gyoung Tae Jin 《Korean Journal of Chemical Engineering》2001,18(5):630-634
A study of N2O decomposition reaction in a fixed bed a reactor over bed of CaO particles has been conducted. Effects of parameters such
as concentration of inlet N2O gas, reacting temperature and content of CO2/ CO gas present in the reacting materials on the decomposition reaction have been investigated. The results showed that the
conversion of N2O decomposition was accelerated by the increase of reaction temperature, and the existence of CO, while the rate was hindered
by the existence of CO2. Heterogeneous gas solid reaction kinetics was proposed for N2O decomposition and compared with homogeneous reaction kinetics.
Presented at the Int’l Symp. on Chem. Eng. (Cheju, Feb. 8–10, 2001), dedicated to Prof. H. S. Chun on the occasion of his
retirement from Korea University. 相似文献