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The Immersed Interface Hybridized Difference Method for Parabolic Interface Problems

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Numerical Mathematics(Theory,Methods and Applications) 2022年第2期15卷 336-359页

作者： youngmok Jeon son-young Yi Department of Mathematics Ajou UniversitySuwon 16499Republic of Korea Department of Mathematical Sciences The University of Texas at El PasoEl PasoTX 79968USA

We propose several immersed interface hybridized difference methods(IHDMs),combined with the Crank-Nicolson time-stepping scheme,for parabolic interface *** IHDM is the same as the hybrid difference method away from the interface cells,but the finite difference operators on the interface cells are modified tomaintain the same accuracy throughout the entire *** themodification process,we consider virtual extensions of two sub-solutions in the interface cells in such a way that they satisfy certain jump equations between *** propose several different sets of jump equations and their resulting discrete methods for one-and two-dimensional *** numerical results are presented to demonstrate the accuracy and robustness of the proposed methods.

关键词： Parabolic interface problem hybrid difference method immersed interface

A facile synthesis of hierarchical Sn3O4 nanostructures in an acidic aqueous solution and their strong visible- light-driven photocatalytic activity

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Nano Research 2015年第11期8卷 3553-3561页

作者： Hui song Su-young son Seul Ki Kim Gun young Jung School of Materials Science and Engineering Gwangju Institute of Science and Technology (GIST) Gwangju 500-712 Republic of Korea Carbon Convergence Materials Research Center Institute of Advanced Composite Materials Korea Institute of Science and Technology (KIST) Jeollabuk-do 565-905 Republic of Korea

Hierarchical tin（Ⅲ） oxide, Sn3O4, nanospheres were synthesized via hydrothermal reaction under strongly acidic ambient conditions. The morphology of Sn3O4 varied with decreasing pH. The prickly SnaO4 nanospheres changed into SnaO4 nanospheres covered with single-crystalline nanoplates having a high BET surface area of ca. 55.05 m^2·g^-1 and a band gap of ca. 2.25 eV. Small amounts （0.05 g） of the hierarchical Sn3O4 nanostructures completely decomposed a 30% methyl orange （MO） solution in 100 mL deionized water within 15 min under one sun condition （UV ＋ visible light）. The Sn3O4 photocatalyst exhibited a fast decomposition rate of 1.73 ×10^-1 min^-1, which is a 90.86% enhancement relative to that of the commercially available P25 photocatalyst. The high photocatalytic activity of the hierarchical Sn3O4 nanostructures is attributed to its ability to absorb visible light and its high surface-to-volume ratio.

关键词： Sn3O4 hierarchical structure hydrothermal morphology engineering photocatalyst

Fast ethylamine gas sensing based on intermolecular charge-transfer complexation

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Chinese Chemical Letters 2012年第4期23卷 484-487页

作者： Eun Mi Lee Seon young Gwon young A son Sung Hoon Kim BK21 FTIT Department of Advanced Organic Materials and Textile System EngineeringChungnam National UniversityDaejeon 305-764Republic of Korea Department of Textile System Engineering Kyungpook National UniversityDaegu 702-701 Republic of Korea School of Chemistry Science & Technology Zhanjiang Normal UniversityZhanjiang 524048China

We have investigated the fast ethylamine gas sensing of 2-chloro-3,5-dinitrobenzotrifluoride（CDBF） loaded poly（acrylonitrile） nanofiber based on an intermolecular charge-transfer *** response and recovery were ach... 详细信息

关键词： Ethylamine gas Fast gas sensing 2-Chloro-3 5-dinitrobenzotrifluoride(CDBF) Electrospinning PAN nanofiber Intermolecular charge-transfer(CT) complexation

Uniform assembly of gold nanoparticles on S-doped g-C3N4 nanocomposite for effective conversion of 4-nitrophenol by catalytic reduction

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Journal of Materials Science & Technology 2020年第5期40卷 176-184页

作者： Vellaichamy Balakumar Hyungjoo Kim Ji Won Ryu Ramalingam Manivannan young-a son Department of Advanced Organic Materials Engineering Chungnam National University220 Gung-dongYuseong-guDaejeon305-764South Korea

In this work,a simple synthesis of sulfur doped graphitic carbon nitride(S-g-C3N4)act as a support cum stabilizers for gold nanoparticles(Au)and its was characterized by UV–vis and XRD to measure the absorbance and crystallinity,*** functional group and morphology of the samples were identified using FT-IR and ***,the Au@S-g-C3N4 nanocatalyst exhibits good catalytic performance and stability in the reduction of hazardous 4-nitrophenol(NP)compared to S-g-C3N4 using Na ***,the Au@S-g-C3N4 nanocomposite holds a good catalytic efficiency(near 100%)achieved by within 5 *** highest catalytic reduction of NP is due to the synergistic effect of Au nanoparticles decorated on *** fast electron transfer reduction mechanism was elucidated and *** reusability and stability of the developed nanocomposites were also observed in consecutive reduction *** filtering and catalyzing device was used for the direct conversion of NP polluted *** method can open a new avenue for the metal nanoparticles based carbon materials heterogeneous catalyst and its reduction of toxic contaminants.

关键词： Gold nanoparticles S-doped g-C3N4 Catalytic reduction 4-nitrophenol

Authentication masking code against DoS of T-MAC protocol

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Journal of Central South University 2013年第7期20卷 1889-1895页

作者： son young-ho HONG Jin-keun BAE Keun-sung Attached Institute of ETRI Division of Information & Communication Baekseok University School of Electrical Engineering & Computer Science Kyungpook National University

Security vulnerability of denial of service (DoS) in time out-medium access control (T-MAC) protocol was discussed and analysis of power consumption at each stage of T-MAC protocol was carried out. For power efficient authentication scheme which can provide reliability, efficiency, and security for a general T-MAC communication, a novel synchronization and authentication scheme using authentication masking code was proposed. Authentication data were repeated and masked by PN sequence. The simulation results show that the proposed approach can provide synchronization and authentication simultaneously for nodes in wireless sensor network (WSN). 63 bits AMC code gives above 99.97% synchronization detection and 93.98% authentication data detection probability in BER 0.031 7.

关键词： time out-medium access control (T-MAC) security vulnerability authentication synchronization authenticationmasking code

Improved speech absence probability estimation based on environmental noise classification

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Journal of Central South University 2012年第9期19卷 2548-2553页

作者： son young-ho LEE Sang-min Department of Electronic Engineering Inha University Institute for Information and Electronics Research Inha University

An improved speech absence probability estimation was proposed using environmental noise classification for speech enhancement.A relevant noise estimation approach,known as the speech presence uncertainty tracking method,requires seeking the "a priori" probability of speech absence that is derived by applying microphone input signal and the noise signal based on the estimated value of the "a posteriori" signal-to-noise ratio(SNR).To overcome this problem,first,the optimal values in terms of the perceived speech quality of a variety of noise types are ***,the estimated optimal values are assigned according to the determined noise type which is classified by a real-time noise classification algorithm based on the Gaussian mixture model(GMM).The proposed algorithm estimates the speech absence probability using a noise classification algorithm which is based on GMM to apply the optimal parameter of each noise type,unlike the conventional approach which uses a fixed threshold and smoothing *** performance of the proposed method was evaluated by objective tests,such as the perceptual evaluation of speech quality(PESQ) and composite *** was then evaluated by a subjective test,namely,mean opinion scores(MOS) under various noise *** proposed method show better results than existing methods.

关键词： speech enhancement soft decision speech absence probability Gaussian mixture model (GMM)

Effect of Laser Parameters on Sintered Powder Morphology

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Journal of Materials Science & Technology 2010年第4期26卷 375-378页

作者： Byeong-Don Joo Jeong-Hwan Jang Jae-Ho Lee young-Myung son young-Hoon Moon Engineering Research Center for Net Shape and Die Manufacturing School of Mechanical EngineeringPusan National University

Selective laser sintering is a kind of rapid prototyping process whereby a three-dimensional part is built layerwise by laser scanning a powder. This process is highly inffuenced by powder and laser parameters such as laser power, scan rate, spot size and layer thickness. Therefore a study on fabricating a line with Fe-Ni-Cr powder on AISI H13 tool steel has been performed by selective laser sintering. In this study, fabrication was performed by experimental facilities consisting of a 200W fiber laser which can be focused to 0.08 mm and atmospheric chamber which can control atmospheric pressure with argon. The line was fabricated with various laser power, scan rate and layer thickness. Line width and surface quality were investigated. With power increase or layer thickness decrease, line width was decreased and line surface quality was improved with scan rate optimization.

关键词： Selective laser sintering Direct fabrication Fiber laser

Laser surface hardening of AISI H13 tool steel

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中国有色金属学会会刊：英文版 2009年第4期19卷 917-920页

作者： Jae-Ho LEE Jeong-Hwan JANG Byeong-Don JOO young-Myung son young-Hoon MOON School of Mechanical Engineering Pusan National University

An attempt was made to improve the surface hardness and wear properties of AISI H13 tool steel through solid solution hardening and refinement of microstructures using a 200 W fiber laser as a heat generating *** hardness of laser melted zone was *** order to identify the effect of heat input on the laser melting zone,scanning conditions were *** results show that,the hardness of as-received AISI H13 tool steel is approximately Hv 240,and the hardness after laser surface heat treatment is around Hv *** hardening depth and width are increased with the increase in the heat input *** of experimental results will be considered in tooling industry.

关键词：激光表面硬化工具钢 H13 激光表面热处理表面硬度信息社会光纤激光器固溶强化

Selective laser melting of Fe-Ni-Cr layer on AISI H13 tool steel

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中国有色金属学会会刊：英文版 2009年第4期19卷 921-924页

作者： Byeong-Don JOO Jeong-Hwan JANG Jae-Ho LEE young-Myung son young-Hoon MOON School of Mechanical Engineering Pusan National University

An attempt to fabricate Fe-Ni-Cr coating on AISI H13 tool steel was performed with selective laser ***-Ni-Cr coating was produced by experimental facilities consisting of a 200 W fiber laser which can be focused to 80 μm and atmospheric chamber which can control atmospheric pressure with N2 or *** layer was fabricated with various process parameters such as laser power,scan rate and fill *** quality and coating thickness were measured and *** different surface patterns,such as typeⅠ,typeⅡand type Ⅲ,are shown with various test conditions and smooth regular pattern is obtained under the conditions as 10 μm of fill spacing,50-350 mm/s of scan rate and 40 μm of fill spacing,10-150 mm/s of scan *** maximum coating thickness is increased with power elevation or scan rate drop,and average thickness of 10 μm fill spacing is lower than that of 40 μm fill spacing.

关键词：镍铬涂层工具钢激光熔融社会扫描速度铁涂层厚度光纤激光器