• 대한화학회지
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• 제29권5호
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• pp.482-489
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• 1985

오클로로옥소몰리브덴(V)산의 치환퀴놀린윰염을 합성하고 착물의 원소분석, 적외선흡수 스펙트럼, 전자스펙트럼, 전기전도도를 측정하였다. 착물은 2:1전해질이고 치환퀴놀린류는 양이온 상태로 존재하고 있으며 착물의 음이온은 단위체이다. 착물의 결정장전이와 전하이동전이를 해석하였다.

• Bulletin of the Korean Chemical Society
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• 제24권6호
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• pp.829-831
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• 2003

Various theoretical studies of σ-bond activation of organic molecules by transition metal complexes arereviewed. In the homolytic σ-bond activation, the d orbital energy level of the central metal is an importantfactor, as well known. At the same time, the electron-withdrawing substituent which stabilizes the sp3 orbitalaccelerates the homolytic σ-bond activation. In the heterolytic C-H σ-bond activation of RH by $MXL_n$, the XHbond formation is an important driving force, where $MRL_n$ and HX are formed as products. The heterolytic σ-bond activation is also understood in terms of the electrophilic attack of the metal center to the substrate.

• Bulletin of the Korean Chemical Society
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• 제24권8호
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• pp.1215-1218
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• 2003

An analysis of the bonding situation in CaM₂P₂ (M=Fe, Ni) with ThCr₂Si₂ structure is made in terms of DOS and COOP plots. The main contributions to covalent bonding are due to M-P and P-P interactions in both compounds. Particularly, the interlayer P-P bonding by variation in the transition metal is examined in more detail. It turns out that the shorter P-P bonds in CaNi₂P₂ form as a result of the decreasing electron delocalization into ${{\sigma}_p}^*$ of P₂ due to the weaker bonding interaction between the metal d and ${{\sigma}_p}^*$ as the metal d band is falling from Fe to Ni.

• 한국세라믹학회지
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• 제26권5호
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• pp.670-676
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• 1989

The PbTiO3 is well known materials having remarkable ferroelectric, piezoelectric, and pyroelectric properties. PbTiO3 thin films with a perovskite structure were successfully fabricated on titanium substrate by chemical vapor deposition. These films were characterized according to composition, crystal structure, and electrical properties. Semi-quantitative compositional analysis of the deposited films was made by Auger Electron Spectroscopy(AES). The PbTiO3 film deposited on titanium substrate at the deposition temperature 75$0^{\circ}C$, the Ti(C2H5O)4 fraction 0.15, and O2 partial pressure 0.06atm, has a columnar structure and grows with(001) preferred orientation, and has stoichiometric composition. A clear dielectric transition and offset in the dc conductivity near the transition temperature(48$0^{\circ}C$) were observed in the deposited lead titanate film.

• 한국자기공명학회논문지
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• 제12권2호
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• pp.103-110
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• 2008

Spin Hamiltonian for the paramagnetic center with a three-fold symmetry and high spin ($S{\geq}2$) multiplicity should contain the fourth order zero-field splitting (ZFS) terms. Electron magnetic resonance transition lines of the center with S = 5/2 are expected to split in a pair when the magnetic field is applied off the principal axes of ZFS, while they are superimposed when the magnetic field is applied parallel to the principal axes of ZFS. In this study we report that the transition lines of $Mn^{2+}$ centers at the three-fold symmetric sites in $LiNbO_3$, chemically equivalent but physically different, split in two due to the nonzero fourth order ZFS term.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 1991년도 추계학술발표회논문집
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• pp.18-22
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• 1991

Far Infrared radiators should have functionality to convert thermal energy into electron wave. In order to apply the Far Infrared to the substance, the absorption characteristics of the substance should be considered. In this paper, interrelation of emissivity with emission energy according to temperature in the range of 2.5$\mu$m to 25$\mu$m after the transition element oxides (MnO2, Fe2O3, CuO, Co3O4) of first grade reagent were molded in press, then they were calcinated in 1050˚C, and they were used as samples.

• 한국고분자학회:학술대회논문집
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• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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• pp.155-155
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• 2006

The most commercially and academically advanced catalysts of late transition metals are diimine complexes based on Pd(II)/Ni(II) and bis(imino)pyridyl complexes based on Fe(II)/Co(II). It is well known that the former systems yield branched polyethylenes and the latter linear PEs. In this presentation, effect of extremely bulky ligands with electron withdrawing/donating substituents at a remote position from Ni(II) metal center and of using multi-nuclear homo or hetero multi-metal on the ethylene polymerization is to be paged.

• Tribology and Lubricants
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• 제8권1호
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• pp.70-77
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• 1992

Al-Pb-Si bearing alloys were produced by a forced stirring method and a rapid solidification process to study wear properties of bearing alloys. A homogeneous distribution of Pb particles in Al matrix could be obtained by means of the forced stirring and the rapid cooling during the casting. The wear properties of bearing alloys were tested by a pin-on-disc wear tester. The change in microstructure according to the alloy manufacturing variables was observed by the backscattered electron images. Al-Pb and Al-Si binary alloys showed a transition from mild to severe wear. The transition was not found in Al-Pb-Si ternary alloys. It could be concluded that the lubricatioin effect of Pb and the strengthening effect of Si in the ternary alloys enhanced the bearing properties. A Al-25%Pb-13%Si alloy showed the lowest coefficient of friction in this experiment. It indicated that the optimum concentration of alloy was 25% Pb and 13% Si when the forced stirring of melt and water-cooled-copper-mold solidification were adopted.

• 한국자기학회지
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• 제21권1호
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• pp.1-4
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• 2011

정육면체 전이금속 산화물 FeO, MnO의 자기적 상호작용을 제1원리의 범밀도함수법을 이용하여 계산하였다. 그 결과, 모두 초교환작용으로 인해 반강자성적 상호작용이 가장 낮은 에너지를 가지고 있었다. 자기이방성은 반강자성 스핀 배열의 FeO 클러스터에서만 발견되었다. 그 원인은 <111> 방향으로 각운동량을 가지는 3d down-spin 전자의 스핀-궤도 결합에 기인하였다.

• 한국생산제조학회지
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• 제21권6호
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• pp.976-981
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• 2012

In this study, hardness, microstructure and temperature of glass transition are measured respectively by using SEM (Scanning electron microscope) and DSC (Differential scanning calorimeter) to analyze the effects on material properties by after-curing in the epoxy resin. As the result of hardness test according to the after-curing conditions, the higher the temperature of after-curing, hardness and heat resistance are, the higher hardness is. As a result of microstructure for each specimen by SEM, it could be confirmed that the specimen with after-curing has more dense fracture surface. It is also found that temperatures of glass transitions by DSC are comparatively higher in the specimens with after-curing, and the differences between after-curing conditions are negligible.