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LOCAL REGULARITY CRITERIA OF A SUITABLE WEAK SOLUTION TO MHD EQUATIONS

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Acta Mathematica Scientia 2017年第4期37卷 1033-1047页

作者： jae-Myoung KIM Department of Mathematical Sciences Seoul National UniversitySeoul 08826Republic of Korea

We present a regularity condition of a suitable weak solution to the MHD equations in three dimensional space with slip boundary conditions for a velocity and magnetic vector fields. More precisely, we prove a suitable weak solution are HSlder continuous near boundary provided that the scaled mixed Lx,t^p,q-norm of the velocity vector field with 3/p ＋ 2/q 〈 2, 2 〈 q 〈 ∞ is sufficiently small near the boundary. Also, we will investigate that for this 3 2〈3 solution U ∈ Lx,t^p,q with 1 〈 3＋p ＋2/q＋≤3/2, 3 〈 p 〈 ∞, the Hausdorff dimension of its singular set is no greater than max{p, q}（3/q＋2/q- 1）.

关键词： local regularity criteria suitable weak solution MHD equations

Distributional Methods for a Class of Functional Equations and Their Stabilities

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Acta Mathematica Sinica,English Series 2007年第11期23卷 2017-2026页

作者： jae Young CHUNG Department of Mathematics Kunsan National UniversityKunsan 573-701South Korea

We consider a class of n-dimensional Pompeiu equations and that of Pexider equations and their Hyers Ulam stability problems in the spaces of Schwartz distributions. First, reducing the given distribution version of functional equations to differential equations we find their solutions. Secondly, using approximate identities we prove the Hyers Ulam stability of the equations.

关键词： Pompeiu equations Pexider equations distributions Hyers Ulam stability

LOCAL EXISTENCE AND BLOW-UP CRITERION OF 3D IDEAL MAGNETOHYDRODYNAMICS EQUATIONS

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Acta Mathematica Scientia 2018年第6期38卷 1759-1766页

作者： jae-Myoung KIM Center for Mathematical Analysis & Computation Yonsei University

We investigate the local existence of smooth solutions of a 3D ideal magneto-hydrodynamics （MHD） equations in a bounded domain and give a blow-up criteria to thisequations with respect to vorticists.

关键词： ideal magnetohydrodynamics equations blow-up criterion bounded domain

Observation of baroclinic eddies southeast of Okinawa Island

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Science China Earth Sciences 2008年第12期51卷 1802-1812页

作者： PARK jae-Hun Graduate School of Oceanography University of Rhode Island

In the region southeast of Okinawa, during May to July 2001, a cyclonic and an anticyclonic eddy were observed from combined measurements of hydrocasts, an upward-looking moored acoustic Doppler current profiler (MADCP), pressure-recording inverted echo sounders (PIESs), satellite altimetry, and a coastal tide gauge. The hydrographic data showed that the lowest/highest temperature (T) and salinity (S) anomalies from a 13-year mean for the same season were respectively ?3.0/+2.5°C and ?0.20/+0.15 psu at 380/500 dbar for the cyclonic/anticyclonic eddies. From the PIES data, using a gravest empirical mode method, we estimated time-varying surface dynamic height (D) anomaly referred to 2000 dbar changing from ?20 to 30 cm, and time-varying T and S anomalies at 500 dbar ranging through about ±2 and°C ±0.2 psu, respectively. The passage of the eddies caused variations of both satellite-measured sea surface height anomaly (SSHA) and tide-gauge-measured sea level anomaly to change from about ?20 to 30 cm, consistent with the D anomaly from the PIESs. Bottom pressure sensors measured no variation related to these eddy activities, which indicated that the two eddies were dominated by baro-clinicity. Time series of SSHA map confirmed that the two eddies, originating from the North Pacific Subtropical Countercurrent region near 20°–30°N and 150°–160°E, traveled about 3000 km for about 18 months with mean westward propagation speed of about 6 cm/s, before arriving at the region southeast of Okinawa Island.

关键词： baroclinic eddy southeast of Okinawa Island PIES ADCP

Stability of a Generalized Quadratic Functional Equation in Schwartz Distributions

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Acta Mathematica Sinica,English Series 2009年第9期25卷 1459-1468页

作者： jae-Young CHUNG Department of Mathematics Kunsan National University Kunsan 573-701 Republic of Korea

We consider the Hyers-Ulam stability problem of the generalized quadratic functional equationuoA＋voB-2woP1 - 2ko P2 =0, which is a distributional version of the classical generalized quadratic functional equation f（... 详细信息

关键词： Hyers-Ulam stability generalized quadratic functional equation distribution heat kernel

Central Aggregator Intrusion Detection System for Denial of Service Attacks

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Computers, Materials & Continua 2023年第2期74卷 2363-2377页

作者： Sajjad Ahmad Imran Raza MHasan Jamal Sirojiddin Djuraev Soojung hur Imran Ashraf Department of Computer Science COMSATS University IslamabadLahore CampusLahore54000Pakistan Department of Software Engineering New Uzbekistan UniversityTashkent100007Uzbekistan Department of Information and Communication Engineering Yeungnam UniversityGyeongsan-si38541Korea

Vehicle-to-grid technology is an emerging field that allows unused power from Electric Vehicles(EVs)to be used by the smart grid through the central *** the central aggregator is connected to the smart grid through a wireless network,it is prone to cyber-attacks that can be detected and mitigated using an intrusion detection ***,existing intrusion detection systems cannot be used in the vehicle-to-grid network because of the special requirements and characteristics of the vehicle-to-grid *** this paper,the effect of denial-of-service attacks of malicious electric vehicles on the central aggregator of the vehicle-to-grid network is investigated and an intrusion detection system for the vehicle-to-grid network is *** proposed system,central aggregator–intrusion detection system(CA-IDS),works as a security gateway for EVs to analyze andmonitor incoming traffic for possible DoS *** are registered with a Central Aggregator(CAG)to exchange authenticated messages,and malicious EVs are added to a blacklist for violating a set of predefined policies to limit their interaction with the CAG.A denial of service(DoS)attack is simulated at CAG in a vehicle-to-grid(V2G)network manipulating various network parameters such as transmission overhead,receiving capacity of destination,average packet size,and channel *** proposed system is compared with existing intrusion detection systems using different parameters such as throughput,jitter,and *** analysis shows that the proposed system has a higher throughput,lower jitter,and higher accuracy as compared to the existing schemes.

关键词： Denial of service attack vehicle to grid network network security network throughput

Study on adhesively-bonded surface of tapered double cantilever specimen made of aluminum foam affected with shear force

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Journal of Central South University 2015年第12期22卷 4521-4527页

作者：孙洪鹏 CHO jae-ung Division of Mechanical Engineering Graduate School Kongju National University Division of Mechanical and Automotive Engineering Kongju National University

Aluminum foam is widely used in diverse areas to minimize the weight and maximize the absorption of shock energy in lightweight structures and various *** presents a number of advantages,such as low density,incombustibility,non-rigidity,excellent energy absorptivity,sound absorptivity and low heat *** aluminum foam with an air cell structure was placed under the TDCB Mode II tensile load by using Landmark equipment manufactured by MTS to examine the shear failure *** angle of the tapered adhesively-bonded surfaces of specimens was designated as a variable,and three models were developed with the inclined angles differing from one another at 6°,8° and 10°.The specimens with the inclined angles of 6°,8° and 10° have the maximum reaction forces of 168 N,194 N when the forced displacements are 6,5 and 4.2 mm *** are three specimens with the inclined angles of 10°,8° and 6° in the order of maximum reaction *** the analysis result,the maximum equivalent stresses of 0.813 MPa and 0.895 MPa happened when the forced displacements of 6 mm and 5 mm proceeded at the models of 6° and 8°,respectively.A simulation was carried out on the basis of finite element method and the experimental *** results of the experiment and the simulation analysis are shown not different from each other ***,only a simulation could be confirmed to be performed in substitution of an experiment,which is costly and time-consuming in order to determine the shearing properties of materials made of aluminum foam with artificial data.

关键词： adhesive displacement force reaction shearing fracture characteristic tapered double cantilever beam(TDCB)

Synthesis of crystalline g-C_(3)N_(4) with rock/molten salts for efficient photocatalysis and piezocatalysis

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Green Energy & Environment 2024年第5期9卷 890-898页

作者： Tingting Xu Jung hur Ping Niu Shulan Wang Sangwook Lee Sang-Eun Chun Li Li Department of Chemistry College of ScienceNortheastern UniversityShenyang110819China State Key Laboratory of Rolling and Automation Northeastern UniversityShenyang110819China School of Metallurgy Northeastern UniversityShenyang110819China School of Materials Science and Engineering Kyungpook National UniversityDaegu41566Republic of Korea School of Industrial Technology Advances Kyungpook National UniversityDaegu41566Republic of Korea

Graphitic carbon nitride(g-C_(3)N_(4))is emerging as a promising visible-light photocatalyst while the low crystallinity with sluggish charge separation/migration dynamics signiﬁcantly restricts its practical ***,synthesizing highly crystalline g-C_(3)N_(4) with sufﬁcient surface activities still remains ***,different from using alkali molten salts which is commonly reported,we propose an approach for synthesis of highly crystalline g-C_(3)N_(4) with FeCl3/KCl rock/molten mixed *** rock salt can serve as the structure-directing template while molten salt provides the required liquid medium for ***,the synthesized photocatalyst showed further enhanced crystallinity and improved surface area along with high p/p*excitation compared with crystalline C_(3)N_(4) prepared from conventional molten-salt *** catalytically advantageous features lead to its superior photocatalytic and piezocatalytic activities with a high reactivity for overall water splitting that is not commonly reported for C_(3)N_(4).This work provides an effective strategy for structural optimization of organic semiconductor based materials and may inspire new ideas for the design of advanced photocatalysts.

关键词： High crystallinity Carbon nitride Photocatalysis Piezocatalysis Overall water splitting

Efficient multi-response adaptive sampling algorithm for construction of variable-fidelity aerodynamic tables

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Chinese Journal of Aeronautics 2019年第3期32卷 547-558页

作者： Maxim TYAN jae-Woo LEE Department of Aerospace Information Engineering Konkuk University

Adaptive sampling is an iterative process for the construction of a global approximation model. Most of engineering analysis tools computes multiple parameters in a single run. This research proposes a novel multi-response adaptive sampling algorithm for simultaneous construction of multiple surrogate models in a time-efficient and accurate manner. The new algorithm uses the Jackknife cross-validation variance and a minimum distance metric to construct a sampling criterion function. A weighted sum of the function is used to consider the characteristics of multiple surrogate models. The proposed algorithm demonstrates good performance on total 22 numerical problems in comparison with three existing adaptive sampling algorithms. The numerical problems include several two-dimensional and six-dimensional functions which are combined into singleresponse and multi-response systems. Application of the proposed algorithm for construction of aerodynamic tables for 2 D airfoil is demonstrated. Scaling-based variable-fidelity modeling is implemented to enhance the accuracy of surrogate modeling. The algorithm succeeds in constructing a system of three highly nonlinear aerodynamic response surfaces within a reasonable amount of time while preserving high accuracy of approximation.

关键词： Adaptive sampling Aerodynamic database Multi-response system Surrogate modeling Variable fidelity modeling