• Composites Research
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• 제29권5호
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• pp.231-235
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• 2016

본 연구에서는 동일한 구조의 모자형 보강재를 이용하여 일체형 동시접착 구조의 보강패널시편을 제작하였다. 일반적인 동시접착 보강패널 시편과 탄소에폭시 복합재를 이용하여 제작된 카울플레이트(Caul Plate)를 적용한 동시접착 보강패널 시편의 2가지 형태 시편을 제작하였으며 일반 동시접착 보강패널 시편에서는 패널 상에서 보강재가 적용되지 않은 부위가 적용된 부위보다 더 두꺼운 패널 두께를 가지고 그 연결부위에는 0.61 mm 높이 및 3.29 mm 길이의 플라이웨이브 현상이 나타났다. 카울플레이트가 적용된 보강패널 시편에서는 보다 균일한 압력 전달로 인하여 0.22 mm 높이와 1.37 mm 길이의 완화된 웨이브 현상을 보이면서 약 50% 이상 개선된 결과를 얻을 수 있었다.

• Bulletin of the Korean Chemical Society
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• 제26권9호
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• pp.1421-1426
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• 2005

The stationary point structures and relative energies between them as well as binding energies of $(CO)_2$ have been investigated at the CCSD(T) level using the correlation-consistent basis sets aug-cc-pVXZ(X=T,Q,5). It is found that while the equilibrium structure corresponds to the C-bonded T-shaped configuration with intermolecular distance of 4.4 $\AA$, there exists another minimum, slightly higher in energy ($\sim$10 $cm^{-1}$) than the global minimum, corresponding to the O-bonded T-shaped configuration with the intermolecular distance of 3.9 $\AA$. The CCSD(T) basis set limit binding energy of $(CO)_2$ is estimated to be 132 $cm^{-1}$.

• 한국항공우주학회지
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• 제42권10호
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• pp.809-815
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• 2014

큰 온도 변화를 받는 이종 접합 복합재는 재료의 서로 다른 열팽창 특성으로 인해 열에 의한 형상 왜곡이 발생되기 쉽다. 성형 과정에서 이종 접합 복합재 구조물의 제작 공정 중의 형상 왜곡 현상을 고려하기 위해서 구성하는 각각의 복합재료들에 대한 열팽창 특성 분석이 우선적으로 요구된다. 본 논문에서는 Carbon/Epoxy와 Silica/Phenolic의 이종접합 복합재료 시편의 열변형 특성을 측정하기 위해 디지털 영상 상관 기법(DIC)을 활용하였다. 이종 접합 복합재 시편의 열변형에 대해 수치 해석을 수행하였고 이를 실험 결과와 비교하였다. 수치해석을 통한 예측 결과는 실험을 통하여 입증되었다.

• 한국재료학회지
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• 제3권2호
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• pp.175-184
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• 1993

Nd-Fe-B계에 Co와 Al을 첨가한 자석합금을 진공유도용해로에서 제조하여 이들 합금을 단롤법으로 melt-spun시켜 급냉리본을 얻었다. 제작된 급냉리본의 냉각속도에 따른 자기적 성질의 변화를 조사하였고, 최적의 급냉속도에서 제작된 리본을 파쇄하여 resin bond 자석을 제조하였으며, 이들 급냉리본 및 bond자석의 자기적 성질, 미세구조, 결정구조에 관하여 연구, 조사하였다. 이들 급냉리본의 자기적 성질은 급냉속도에 따라 크게 변하였으며 20m/sec전후에서 최적의 자기적 성질을 보였다. 이때의 급냉리본의 미세조직은 Nd-rich의 입계상이 미세한 N$d_2$F$e_14$B결정립을 둘러싼 cell 형의 구조였으며, 특히 Al이 2.1at%첨가된 리본시료에서는 iHc=15.5KOe, Br=7.8KG, (BH)max=8.5MGOe의 자기적 성질을 나타내었다. 최적의 급냉속도에서 제작된 리본을 polyamide resin과 2.5wt%의 비율로 혼합하여 상온에서 성형, 결합시켜 제작한 bond자석에서 보다 현저히 향상되었으며 유지시간이 8분인 경우 iHc=10.8KOe, Br=7.3KG, (BH)max=8.0MGOe의 값을 가졌다. 한편, 자구구조는 maze pattern이 주로 관찰되어 자화용이축인 C축이 배열되었으며 bond자석에서보다 hot-press 자석에서 자구폭이 보다 작았다.

• Bulletin of the Korean Chemical Society
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• 제7권6호
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• pp.413-421
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• 1986

Hydrocarbon solution of $Cp_2Zr(CH_3)Cl$ react rapidly with $Na_2Fe(CO)_4$ (1/2 equiv.) to yield $[Cp_2Zr(CH_3)]_2Fe(CO)_4$ and NaCl. The more soluble metal-metal bonded complex $[Cp_2ZrC_8H_{17}]_2Fe(CO)_2$ has also been prepared through the reaction of $Cp_2Zr(C_8H_{17})BF_4$ and $Na_2Fe(CO)_4 (1/2 equiv.). The complexes were characterized by IR, $^1H$ NMR, ^{13}C$ NMR, and elemental analysis. The infrared spectrum of $[Cp_2ZrR]_2Fe(CO)_4$ shows four bands, which is indicative of a cis-structure. The $^{13}C$ NMR spectrum provides evidence for the cis-structure.

• Bulletin of the Korean Chemical Society
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• 제25권5호
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• pp.676-680
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• 2004

Complexes M($C_7H_2NO_5)3H_2O{\cdot}H_2O{\cdot}0.25MeCN$ (M=Ni, Co) were crystallized from the reactions of $Ni(CH_3COO)_2{\cdot}4H_2O\;or\;Co(CH_3COO)_2{\cdot}2H_2O$ with KSCN and 2,6-dicarboxy-4-hydroxypyridine (chelidamic acid). The structures were characterized by X-ray crystallography. The crystal structures of 1 and 2 show a distorted octahedral coordination geometry around the M(II) ions, which are chelated by one nitrogen atom and two oxygen atoms of the chelidamic acid and three water molecules. Complexes 1 and 2 display the hydrogen-bonded 3D framework. The magnetic behavior of 2 exhibits antiferromagnetic interaction.

• Bulletin of the Korean Chemical Society
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• 제16권7호
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• pp.634-641
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• 1995

The metal-carbon σ-bond cluster complexes 1-Mn(CO)5-2-R-1,2-C2B10H10 (R=CH3 Ia, C6H5 Ib) have been prepared in good yields from readily available carboranyl lithium complexes, 1-Li+-2-R-1,2-C2B10H10- (R=CH3, C6H5), by direct reaction with (CO)5MnBr. These manganese metal complexes are rapidly converted to the corresponding manganese metal carbene complexes, 1-[(CO)4Mn=C(OCH3)(CH3)]-2-R-1,2-C2B10H10 (R=CH3 IIIa, C6H5 IIIb), via alkylation with methyllithium followed by O-methylation with CF3SO3CH3. The crystal structure of IIIb was determined by X-ray diffraction. Thus, complex IIIb crystallizes in the orthorhombic space group P212121 with cell parameters a=15.5537(5), b=19.0697(5), c=7.4286(3) Å, V=2203.4(1) Å3, and Z=4. Of the reflections measured a total of 3805 unique reflections with F2>3σ(F2) was used during subsequent structure refinement. Refinement converged to R1=0.053 and R2=0.091. Structural studies showed that the manganese atom had a slightly distorted pseudo-octahedral configuration about the metal center with the carbene and ortho-carborane occupying the equatorial plane cis-orientation to each other.

• Journal of Advanced Marine Engineering and Technology
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• 제30권2호
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• pp.304-310
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• 2006

A typical honeycomb sandwich panel consists of two thin, high-strength facings bonded to a thick, light-weight core. Each component by itself is relatively weak and flexible, but when it combined in a sandwich panel they produce a structure that is stiff, strong, and lightweight. To prove the suitability the honeycomb sandwich structure with prepreg, the mechanical properties of the skin materials and honeycomb sandwich structure were evaluated with the static strength tests. Accordingly, the honeycomb sandwich structure made by autoclave process is available for a panel on LCD/PDP assembly line.

• 대한기계학회논문집B
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• 제30권12호
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• pp.1196-1202
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• 2006

A MEMS methanol reformer was fabricated and its performance was evaluated in the present study. Catalytic steam reforming of methanol was selected because the process had been widely applied in macro scale reformers. Conventional Cu/ZnO catalyst that was prepared by co-precipitation method to give the highest coating quality was used. The reactor structure was made by bonding three layers of glass wafers. The internal structure of the wafer was fabricated by the wet-etching process that resulted in a high aspect ratio. The internal surface of the reactor was coated by catalyst and individual wafers were fusion-bonded to form the reactor structure. The internal volume of the microfabricated reactor was $0.3cm^3$ and the reactor produced exhaust gas with hydrogen concentration at 73%. The production rate of hydrogen was 4.16 ml/hr that could generate power of 350 mW in a typical PEM fuel cell.

• Journal of Magnetics
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• 제10권4호
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• pp.137-141
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• 2005

We confirmed that the improvement in properties of magnetic tunnel junctions prepared by radical oxidation after thermal treatment was mostly resulted from the redistribution of oxygen at the $AIOx/Co_{90}Fe_{10}$ interface. The as-deposited Al oxide barrier was oxygen-deficient but most of it re-oxidized into $Al_2O_3$, the thermodynamically stable stoichiometric phase, through thermal treatment. As a result, the effective barrier height was increased from 1.52 eV to 2.27 eV. On the other hand, the effective barrier width was decreased from 8.2 ${\AA}$ to 7.5 ${\AA}$. X-ray absorption spectra of Fe and Co clearly showed that the oxygen in the CoFe layer diffused back into the Al barrier and thereby enriched the barrier to close to a stoichiometirc $Al_2O_3$ phase. The oxygen bonded with Co and Fe diffused back by 6.8 ${\AA}$ and 4.5 ${\AA}$ after thermal treatment, respectively. Our results confirm that controlling the chemical structures of the interface is important to improve the properties of magnetic tunnel junctions.