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Impedance spectroscopy study on Mn_(1+x)Fe_(2-2x)Ti_xO_4(0≤x≤0.5) ferrites

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journal of Central South University 2010年第6期17卷 1133-1138页

作者： kUMAR S BATOO k M PRAkASh R ChOI h k kOO B h SONG j I chung h jEONG h LEE C G School of Nano and Advanced Materials Engineering Changwon National UniversityChangwon 641773Korea king Abdullah Institute for Nanotechnology King Saud UniversityRiyadh 11451Saudi Arabia Department of Mechanical Engineering Changwon National UniversityChangwon 641773Korea Department of Precision & Mechanical Engineering and Bk21 Eco-Friendly heat & Cold Energy Mechanical Research Team Gyeongsang National U niversityTongyeong 650160Korea

The complex impedance spectroscopy and surface morphology of Mn1+xFe2-2xTixO4(0≤x≤0.5) system,prepared using a conventional solid state reaction technique,were *** impedance spectroscopy measurements were carried out at room temperature in the frequency range of 42-5 *** electrical processes in the samples were modeled in the form of an equivalent circuit made up of a combination of two parallel RC circuits attributed to grain and grain *** DC conductivity obtained by extrapolation of AC data using impedance spectroscopy and four-probe method increases at 10% doping of Ti *** energy-dispersive X-ray(EDX) pattern confirmed the homogeneous mixing of the Mn,Fe,Ti and O atoms in pure and doped ferrite samples.

关键词： spinel ferrite magnetic properties impedance spectroscopy Ti4+ ions doping

Conformable fractional heat equation with fractional translation symmetry in both time and space

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Chinese Physics B 2023年第4期32卷 125-129页

作者： W S chung A Gungor j krız B C Lutfuoglu h hassanabadi Department of Physics and Research Institute of Natural Science College of Natural ScienceGyeongsang National UniversityJinju 660-701Korea Mechanical Engineering Akdeniz UniversityAntalyaTurkey Department of Physics University of Hradec KraloveRokitanskeho 6250003 Hradec KraloveCzech Republic Department of Physics Akdeniz UniversityAntalyaTurkey Faculty of Physics Shahrood University of TechnologyShahroodIran

We investigate the fractional heat equation with fractional translation in both time and position with different fractional *** examples,we consider a rod and anα-disk with an initial constant temperature and discuss... 详细信息

关键词： fractional derivative heat equation conformable symmetry

Influence of Ti^(4+) doping on hyperfine field parameters of Mg_(0.95)Mn_(0.05)Fe_(2-2x)Ti_(2x)O_4(0≤x≤0.7)

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journal of Central South University 2010年第6期17卷 1139-1143页

作者： kUMAR S PRAkASh R ALIMUDDIN ChOI h k kOO B h SONG j I chung h jEONG h LEE C G School of Nano and Advanced Materials Engineering Changwon National UniversityChangwon 641773Korea Department of Mechanical Engineering Changwon National UniversityChangwon 641773Korea Department of Applied Physics Aligarh Muslim UniversityAligarh 202002India Department of Precision & Mechanical Engineering and Bk21 Eco-Friendly heat & Cooling Energy Mechanical Research Team Gyeongsang National U niversityTongyeong 650160Korea

The mixed spinel ferrite system Mg0.95Mn0.05Fe2-2xTizxO4 （0 ≤x ≤ 0.7） was synthesized by the conventional solid-state reaction technique. The effect of Ti^4＋ doping was studied by using the Moessbauer spectroscopy measurements at room temperature. From the analysis of the Moessbauer spectra, it is observed that s-electron density, electric field gradient （EFG）, quadrupole coupling constant （QCC） and the net hyperfine magnetic fields acting on the Moessbauer nuclei-FeA^3＋ and FeB^3＋ change with the increase of Ti^4＋ doping in Mg0.95Mn0.05Fe2O4. The hyperfine magnetic field decreases with the increase of Ti^4＋ doping.

关键词： spinel ferrite Moessbauer spectroscopy hyperfine magnetic field isomer shift Ti^4+ doping

Mssbauer spectra of MnFe_(2-2x)Al_(2x)O_4(0≤x≤0.4) ferrites

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journal of Central South University 2010年第6期17卷 1129-1132页

作者： BATOO k M kUMAR S PRAkASh R ALIMUDDIN SONG j I chung h jEONG h kOO B h LEE C G king Abdullah Institute for Nanotechnology King Saud UniversityRiyadh 11451Saudi Arabia School of Nano and Advanced Materials Engineering Changwon National UniversityChangwon 641773Korea Department of Mechanical Engineering Changwon National UniversityChangwon 641773Korea Department of Applied Physics Aligarh Muslim UniversityAligarh 202002India Department of Precision & Mechanical Engineering and Bk21 Eco-Friendly heat & Cooling Energy Mechanical Research Team Gyeongsang National U niversityTongyeong 650160Korea

The effect of non-magnetic Al^3＋ ion doping on the magnetic properties of MnFe2-2x Al2xO4 （0 ≤x≤ 0.4） spinel ferrites was studied using Moessbauer spectroscopy measurements at room temperature. From the Moessbauer study, it is observed that the ：esolved hyperfine sextets are due to the distribution of Fe ions on the two sublattices of the spinel ferrites. The value of the isomer shift obtained from the fitting of the Moessbauer spectra indicates that Fe ions are in ＋3 state. A paramagnetic doublet is observed at ：iegree of inversion x=0.4, superimposed on the hyperfine sextets, indicating that the super-exchange interaction A-B decreases due to ：he dilution of sublattice by Al^3＋ ions. The hyperfine magnetic field decreases at both interstitial sites of tetrahedral （A） and 3ctahedral （B） with the increase in Al concentration.

关键词： ferrites hyperfine interactions Moessbauer spectroscopy isomer shift

hetero-deformation promoted strengthening and toughening in BCC rich eutectic and near eutectic high entropy alloys

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journal of Materials Science & Technology 2023年第15期146卷 1-9页

作者： D.h.chung j.Lee Q.F.he Y.k.kim k.R.Lim h.S.kim Y.Yang Y.S.Na Department of Special Alloys Extreme Materials Research InstituteKorea Institute of Materials ScienceChangwonThe Republic of Korea Department of Mechanical Engineering City University of Hong KongKowloon TongKowloonHong KongChina Graduate Institute of Ferrous Technology Pohang University of Science and TechnologyPohangThe Republic of Korea Center for heterogenic Metal Additive Manufacturing Pohang University of Science and TechnologyPohangThe Republic of Korea Department of Materials Science and Engineering City University of Hong KongKowloon TongKowloonHong KongChina

heterostructured eutectic high-entropy alloys(EhEAs)have attracted significant attention owing to their novel properties,such as balanced combinations of strength and fracture ***,the toughening/strengthening mechanisms of these EhEAs have not been thoroughly *** this study,we developed a series of dual-phase Al_((18–2x))Co_(30)Cr_((11+x))Fe_((11+x))Ni_(3)0(x=-1,0,1)eutectic and neareutectic hEAs containing face-centered cubic(FCC)and body-centered cubic(BCC)*** the high amount of BCC,which is referred to as the brittle phase,newly developed EhEAs exhibited superior fracture ***,we discovered that a fully eutectic hEA exhibited further improvements in both yield stress and fracture toughness,outperforming our off-eutectic and other previously reported *** combining experiments and theoretical models,we demonstrated that the synergistic increase in both strength and toughness in our fully eutectic hEA was derived from the high hetero-deformationinduced(hDI)strengthening/toughening associated with a high misorientation angle at the grain/phase boundaries.

关键词： Eutectic high entropy alloy Fracture toughness heterogeneous structure hetero deformation induced strengthening Misorientation angle

The Formation of Nano-Size SiO_2 Thin Film on an Aluminum Plate with hexamethyldisilazane (hMDSA) and hexamethyldisiloxane (hMDSO)

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journal of Thermal Science 2003年第1期12卷 89-96页

作者： h.k.Ma E.Zhao k.M.chung C.L.Yeh Dept of Mechanical Engineering National Taiwan UniversityDept of Mechanical Engineering National Taiwan UniversityDept of Mechanical Engineering National Taiwan UniversityDept of Mechanical Engineering Da-Yeh University 112 Taipei Taiwan 10764 China Taipei Taiwan 10764 ChinaTaipei Taiwan 10764 ChinaShan-Jeau Rd Dah-Tsuen Chang-Hwa Taiwan 51505 China

This study is using hMDSA (C6h19NSi2) or hMDSO (C6h18OSi2) vapor into C3h8/air premixed flames to form SiO2 thin film on the surface of an aluminum plate. With the addition of hMDSO or hMDSA to premixed flames, an orange secondary flame or a flame brush appeared and was contributed to the formation of Sio2 particles. Based upon the EDS, XPS and FTIR analysis, it is believed that the synthesized products consist of mainly SiO2 and a small amount of SiO. The pure SiO2 crystal structure, was proved by XRD analysis, which may form from the SiO2 amorphous structure after high temperature (1300C) thermal treatment. The nano-size SiO2 particles, which ranged from 2.5-25 nm, are proved by analysis of the BET and TEM. A 2-D CFD-RC code with 12 reduced chemical reaction mechanism, based upon the SIMPLER procedure, was successfully employed to predict the flame temperature and both of the SiO2 and SiO concentration profiles. Compared with the experimental results, the calculated temperature profiles in the post-flame region are in good agreement with the measured data and observation phenomena.

关键词： nano size thin film SiO2.

Extraction of Nuclear Matter Properties from Nuclear Masses by a Model of Equation of State

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Communications in Theoretical Physics 2001年第11期36卷 583-588页

作者： k.C.chung C.S.Wang A.j.Santiago Instituto de Fisica Universidade do Estado do Rio de JaneiroRio de Janeiro-RJ 20559-900Brazil Instituto de FisicaUniversidade do Estado do Rio de JaneiroRio de Janeiro-RJ 20559-900Brazil Instituto de FisicaUniversidade do Estado do Rio de JaneiroRio de Janeiro-RJ 20559-900Brazil

The extraction of nuclear matter properties from measured nuclear masses is investigated in the energy density functional formalism of *** is shown that the volume energy a1 and the nuclear incompressibility ko depend essentially on μnN -+- pZ - 2EN,whereas the symmetry energy j and the density symmetry coefficient L as well as symmetry incompressibility ks depend essentially on μn - μp,where μp ＝μp - Ec/ Z,μn and μp are the neutron and proton chemical potentials respectively,EN the nuclear energy,and Ec the Coulomb *** obtained symmetry energy is j ＝ 28.5 MeV,while other coefficients are uncertain within ranges depending on the model of nuclear equation of state.

关键词： nuclear matter properties,nuclear matter equation of state

Design Features and Commissioning of the Versatile Experiment Spherical Torus (VEST) at Seoul National University

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Plasma Science and Technology 2013年第3期15卷 244-251页

作者： k.j.chung Y.h.AN B.k.jUNG h.Y.LEE C.SUNG Y.S.NA T.S.hAhM Y.S.hWANG Department of Nuclear Engineering Seoul National University

A new spherical torus called VEST （Versatile Experiment Spherical Torus） is designed, constructed and successfully commissioned at Seoul National University. A unique design feature of the VEST is two partial solenoid coils installed at both vertical ends of a center stack, which can provide sufficient magnetic fluxes to initiate tokamak plasmas while keeping a low aspect ratio configuration in the central region. According to initial double null merging start-up scenario using the partial solenoid coils, apprdpriate p6wer supplies for driving a toroidal field coil, outer poloidal field coils, and the partial solenoid Coils are fabricated and successfully commissioned. For reliable start-up, a pre-ionization system with two cost-effective homemade magnetron power supplies is also prepared. In addition, magnetic and spectroscopic diagnostics with appropriate data acquisition and control systems are well prepared for initial operation of the device. The VEST is ready for tokamak plasma operation by completing and commissioning most of the designed components.

关键词： spherical torus partial solenoids double null merging start-up

hard Winter Wheat and Flour Properties in Relation to Breadmaking Quality of Straight-dough Bread:Flour Particle Size and Bread Crumb Grain

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食品科学 2006年第11期27卷 164-170页

作者： S h Park O k chung P A Seib USDA-ARS Grain Marketing and Production Research Center Manhattan KS 66502 USA Department of Grain Science and Industry Kansas State University Manhattan KS 66506 USA

Samples of 12 hard winter wheats and their flours that produced breads varying in crumb grain scores were studied for 38 quality parameters including: wheat physical and chemical characteristics; flour ash and protein contents,starch damage,swelling power,pasting characteristics,and flour particle size distribution; dough properties determined by a mixograph; and breadmaking properties for pup loaves (100g flour). Only two parameters,the protein content of wheat and the granulation of flour,showed significant correlations with bread crumb grain scores. Protein content of wheat ranging 12.9%～14.5% determined by an NIR method showed a weak inverse relationship (r =-0.61,ph bread crumb grain score. Flour particle size distribution measured by both Alpine Air jet Sieve and NIR methods revealed that the weight wt % of particles less than 38μm in size and representing 9.6%～19.3% of the flour weights was correlated positively (r =0 .78,ph crumb grain score,whereas wt % of flour particles larger than 125μm had an inverse relationship (r =-0.60,ph crumb grain score.

关键词： hard Winter Wheat and Flour Properties in Relation to Breadmaking Quality of Straight-dough Bread