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The Minimal Free Resolution of a Fat star-Configuration in Pn

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Algebra Colloquium 2014年第1期21卷 157-166页

作者： Jeaman ahn Yong su shin Department of Mathematics Education Kongju National University 182 Shinkwan-dong Kongju Chungnam 314-701 Korea Department of Mathematics Sungshin Women's University Seoul 136-742 Korea

Abstract. We find the minimal free resolution of a fat star-configuration X in Pn of type （r, s,t） defined by general forms of degrees d1,...,dr, and show that a fat linear star- configuration X in P2 never has generic hilbert function if （s,t） ≠ （1, 1） or （2, 2）. These two results generalize the interesting results of [2].

关键词： hilbert functions minimal free resolutions weak Lefs.h.tz property fat star-configurations

An efcient GP approach to recognizing cognitive tasks from fNIRs neural signals

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science China(Information sciences) 2013年第10期56卷 277-283页

作者： AN Jinungn LEE Jonghyun ahn ChangWook Robotics Research Division Daegu Gyeongbuk Institute of Science & Technology Department of Computer Engineering Sungkyunkwan University

This paper presents a new genetic programming(GP)approach to accurately classifying cognitive tasks from non-stationary and noisy fNIRs neural *** this end,a new GP that efectively handles multiclass problems is *** accordance with multi-tree structure,GP operators are innovated:crossover exchanges every subtree of parents without sufering from any incongruity problem and mutation fne-tunes candidate solutions by a less destructive *** results verifes the efectiveness of the proposed GP classifer over existing references.

关键词： classifcation cognitive task genetic programming fNIRs multi-tree representation

stabilization of linear systems with distributed input delay using reduction transformation

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Chinese science Bulletin 2011年第13期56卷 1413-1416页

作者： ChOON Ki ahn Faculty of the Department of Automotive Engineering Seoul National Universty of Science and Technology

We propose a new stabilization method for linear systems with distributed input delay via reduction transformation and Riccati equation *** the presented stabilization s.h.me,the gain matrix of controller is constructed by the well-known linear control technique for delay-free *** transformation kernel matrix can be determined by solving the non-symmetric matrix Riccati equation backward with the boundary *** point delay systems are considered,it will be shown that the proposed control law degenerates to the standard one for input delay systems.

关键词：延迟系统线性系统分布式输入稳定 Riccati方程非线性控制技术矩阵构造

Field-dependent resistive transitions in YBa_2Cu_3O_(7-δ) thin films:Influence of the pseudogap on vortex dynamics

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Chinese Physics B 2015年第1期24卷 467-473页

作者： s.h.Naqib R s Islam Department of Physics University of RajshahiRajshahi-6205 Bangladesh

The nature of resistive transition of high-quality crystalline thin films of YBa2Cu3O7-δhas been studied under magnetic fields.h. applied along the c direction over a wide range of doped holes, p, in the Cu O2 planes. The field- and temperature-dependent in-plane resistivity, ρab（T, h）, has been analyzed within the thermally assisted flux-flow（TAFF）formalism. The flux activation energy, U（T, h）, has been extracted from this analysis. The low-T part of the ρab（T, h）data can be described by an activation energy having the functional form of U（T, h） =（1- t）m（h-0/h）β, where t = T /Tc（reduced temperature）, and h0 is a field scale that primarily determines the magnitude of U（T, h）. The temperature exponent, m, shows a systematic variation with p, whereas the field exponent, β, is insensitive to the p values and is close to unity. The h0, on the other hand, changes rapidly as p is varied. U（T, h） is linked to the pinning potential and consequently on the superconducting condensation energy. since the normal state pseudogap directly affects superconducting condensation energy, a clear correspondence between h0 and the PG energy scale, ε g, is found. Possible implications of these results are discussed.

关键词： Y123 superconductors thermally assisted flux-flow model activation energy pseudogap

Adaptive h∞ Chaos Anti-synchronization

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Chinese Physics Letters 2010年第3期27卷 64-67页

作者： Choon Ki ahn Faculty of the Division of Electronics and Control Engineering Wonkwang University 344-2 Shinyong-dong Iksan 570-749 Korea

A new adaptive h∞ anti-synchronization （AhAs） method is proposed for chaotic systems in the presence of unknown parameters and external disturbances. Based on the Lyapunov theory and linear matrix inequality formulation, the AhAs controller with adaptive laws of unknown parameters is derived to not only guarantee adaptive anti-synchronization but also reduce the effect of external disturbances to an h∞ norm constraint. As an application of the proposed AhAs method, the h∞anti-synchronization problem for Genesio-Tesi chaotic systems is investigated.

关键词： synchronization Methods Adaptation Adaptability

Piezoelectric polarization and quantum size effects on the vertical transport in AlGaN/GaN resonant tunneling diodes

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Chinese Physics B 2016年第6期25卷 483-488页

作者： Dakhlaoui h Almansour s Department of Physics College of Science for GirlsUniversity of Dammam (UOD)

In this work,the electronic properties of resonant tunneling diodes（RTDs） based on GaN-AlxGa（1-x）N double barriers are investigated by using the non-equilibrium Green functions formalism（NEG）.These materials each present a wide conduction band discontinuity and a strong internal piezoelectric field,which greatly affect the electronic transport *** electronic density,the transmission coefficient,and the current–voltage characteristics are computed with considering the spontaneous and piezoelectric *** influence of the quantum size on the transmission coefficient is analyzed by varying GaN quantum well thickness,AlxGa1-xN width,and the aluminum concentration *** results show that the transmission coefficient more strongly depends on the thickness of the quantum well than the barrier;it exhibits a series of resonant peaks and valleys as the quantum well width *** addition,it is found that the negative differential resistance（NDR） in the current–voltage（I–V） characteristic strongly depends on aluminum concentration *** is shown that the peak-to-valley ratio（PVR） increases with xAlvalue *** findings open the door for developing vertical transport nitrides-based IsB devices such as Thz lasers and detectors.

关键词： nitride semiconductor resonant tunneling diode current density

Determination of recovery factor for simulation of non-equilibrium sedimentation in reservoir

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International Journal of sediment Research 2015年第1期30卷 68-73页

作者： Jungkyu ahn ChihTed YANG Civil and Environmental Engineering Department Seoul National University hydroscience and Training Center Civil and Environmental Engineering DepartmentColorado State University

It is generally acceptable to assume that bed material load is equal to sediment transport capacity,if the exchange between bed and flow occurs ***,for non-equilibrium sediment transport process,there are spatial and temporal delay *** is especially true for reservoir sedimentation *** factor is a coefficient for non-equilibrium sediment *** detemiination of recovery factor can be obtained either experimentally or *** is no consensus on the value of recovery factor in previous *** simulations with a semi-two dimensional sediment transport model,GsTARs4,were conducted in this study using various methods for the determination of recovery factor proposed by previous *** results of a reservoir geometric change were sensitive to the selection of recovery *** was found that the recovery factor as a function of sediment size provided the most reasonable result.A functional relationship between recovery factor and sediment size was determined by comparing simulated and measured reservoir geometric *** sediment has small value of recovery factor.

关键词： Non-equilibrium sediment transport Recovery factor GsTARs Reservoir sedimentation sediment transport

Integration of earth-abundant cocatalysts for high-performance photoelectrochemical energy conversion

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Journal of Energy Chemistry 2024年第1期88卷 336-355,I0008页

作者： Joonhee Ma sang hyun ahn soo Young Kim Department of Materials science and Engineering Korea UniversitySeoul 02841Republic of Korea s.h.ol of Chemical Engineering and Materials science Chung-Ang University84 Heukseok-roDongjak-guSeoul 06974Republic of Korea

Photoelectrochemical(PEC)energy conversion has emerged as a promising and efficient approach to sustainable energy harvesting and *** utilizing semiconductor photoelectrodes,PEC devices can harness solar energy and drive electrochemical reactions such as water splitting or carbon dioxide(CO_(2))reduction to generate clean fuels and value-added ***,PEC energy conversion faces several challenges such as.h.gh overpotential,sluggish reaction kinetics,charge carrier recombination,and stability issues,which limit its practical ***,significant research has been conducted to improve the overall conversion efficiency of PEC *** particularly promising approach is the use of cocatalysts,which involves introducing specific cocatalysts onto the photoelectrode surface to promote charge separation,improve reaction kinetics,and reduce the overpotential,thereby enhancing the overall performance of PEC energy *** review provides a comprehensive overview of the recent developments in the earth-abundant cocatalysts for PEC water splitting and CO_(2) *** main earth-abundant catalysts for the PEC water splitting include transition-metal dichalcogenide(TMD)-based materials,metal phos.h.des/carbides,and metal oxides/***,PEC-CO_(2)RR was divided into C_(1) and C_(2+)based on the final product since various products could be produced,focusing on diverse earth-abundant materials-based *** addition,we provide and highlight key advancements achieved in the very recent reports on novel PEC system design engineering with ***,the current problems associated with PEC systems are discussed along with a suggested direction to overcome these obstacles.

关键词： solar energy Photo-electrochemical Water splitting CO_(2)reduction Cocatalysts

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