• 한국결정학회지
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• 제15권2호
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• pp.74-77
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• 2004

Dinitroethylenediaminepalladium(II), $Pd(C_2H_8N_2)\;(NO_2)_2$의 결정구조는 a=7.425(3), b=8.480(4), c=11.885(2)${\AA}$, 사방정계(Orthorhombic), 공간군 $A2_1ma$, 공간군 번호 36이며, Z=4, V=748.3(4)${\AA}^3,\;D_c=2.295\;gcm^{-3},\;{\mu}=2.457mm^{-1}$이었다. 구조분석은 중금속법으로 풀었으며, 최소 자승법으로 정밀화하였고, 최종 신뢰도 값들은 377개의 회절반점에 대하여 $(R_1=0.0306,\;R_w=0.0802,\;R_{all}=0.0320,\;S=1.166)$이었다. 최종 분석한 착염의 결합거리와 각들은 기존에 알려진 해당 자료들에 상응하였다. 착염의 구조는 Reiset's salt type 유사체와 같은 일차원 구조로써 c축을 따라서, Pd-Pd 거리가 3.762(2) $(\AA)$이고, 각 $161.41(5)^{\circ}$인 지그재그 사슬구조를 형성하고 있다. 사슬내에서나 사슬간에는 질소와 산소사이에 각각 3.05(1)과 3.15(1) ${\AA}$인 수소결합으로 연결되어 있다.

• 한국생물물리학회:학술대회논문집
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• 한국생물물리학회 2003년도 정기총회 및 학술발표회
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• pp.75-75
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• 2003

We report here the results on N-acetyl-N'-dimethylamide of proline (Ac-Pro-NM $e_2$) calculated using the ab initio molecular orbital method with the self-consistent reaction field (SCRF) theory at the HF level with the 6-31+G(d) basis set to investigate the conformational preference of polyproline depending on the cis/trans peptide bonds and down/up puckerings along the backbone torsion angle $\square$ in the gas phase, chloroform, and water. In the gas phase, Ac-Pro-NM $e_2$ has seven local minima of tFd, tFu, cFd, cFu, cAu, tAu, and cAd conformations. In particular, polyproline conformations tFd, tFu, cFd, and cFu are found to be more stable than $\square$-helical conformations cAu, tAu, and cAd. In contrast, Ac-Pro-NHMe has seven local minima of tCd, tCu, cBd, cAu, tAu, cFd, and cFu conformations. Conformations tCd and tCu are found to be most stable, which is ascribed to the intramolecular hydrogen bond between C=O of acetyl group and $N^{~}$ H of N'-methyl amide group. The stability of the cFd conformation (i.e., the polyproline I structure) in chloroform is somewhat increased, relative to that in water, although tFd and tFu conformations (i.e., the polyproline II structure) are dominate both in chloroform and water. The population of backbone conformations feasible in chloroform and water is consistent with the experiments. This work is supported by a Korea Research Foundation Grant (KRF-2002-041-C00129).

• 한국결정성장학회지
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• 제24권1호
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• pp.41-45
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• 2014

다양한 공정 조건으로 $SiN_x$와 $SiO_2$ 박막을 형성하고 이에 대한 패시베이션 특성에 대한 연구를 수행하였다. Plasma enhanced chemical vapor deposition(PECVD)을 이용하여 증착된 $SiN_x$ 박막의 경우, 증착 두께가 증가함에 따라 페시베이션 특성이 향상되는 것을 관찰하였다. 이는 PECVD 증착 공정 중 유입되는 수소 원자들이 실리콘 표면에 존재하는 Dangling bond와 결합하여 소수 캐리어의 재결합 현상을 효과적으로 감소시켰기 때문이다. 건식 산화법으로 형성된 $SiO_2$ 박막은 습식 산화법으로 형성된 것 보다 치밀한 계면 구조를 가짐으로 인하여 약 20배 이상 우수한 패시베이션 특성을 나타내었다. 건식 산화 공정 온도가 증가함에 따라 패시베이션 특성이 열화되는 현상이 발생하였고, Capacitance-voltage(C-V) 및 Conductance-voltage(G-V) 분석을 통하여 $SiO_2$/실리콘 계면에 존재하는 계면 결함 밀도 증가에 의해 나타나는 현상임을 알 수 있었다.

• Bulletin of the Korean Chemical Society
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• 제33권11호
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• pp.3777-3787
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• 2012

Three kinds of 3D isomorphous and isostructural coordination polymers, namely, $\{[Ln_2(PDA)_3(H_2O)_3]{\cdot}0.25H_2O\}_{\infty}$ (Ln = La(1), Sm(2), and Gd(3)) ($PDA^{2-}$ = pyridine-2,6-dicarboxylate anion) have been synthesized under hydrothermal conditions and characterized by elemental analyses, IR spectroscopy, thermal analyses and single crystal X-ray diffraction. In these MOFs, Ln(III) centers adopt eight-coordinated and nine-coordinated with the $N_1O_7$ and $N_2O_7$ donor sets to construct distorted trianglar dodecahedron geometry and tricapped trigonal prism configurations, respectively. Based on the building block of tetranuclear homometallic $Ln_4C_4O_8$ unit (16-membered ring), 1-3 are connected into highly ordered 2D sheets via O-C-O linkers and further constructed into 3D architectures through hydrogen bonds. Crystallographic parameters suggest that the lanthanide contraction effect exist in these coordination polymers. Luminescent properties of the lanthanide-based MOFs (metal-organic frameworks) have been measured at room temperature, which reveal that they presenting ionselective characters toward certain metals, such as $Mg^{2+}$, $Cd^{2+}$ and $Pb^{2+}$ ions.

• ETRI Journal
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• 제16권1호
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• pp.45-57
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• 1994

The effects of reactive ion etching (RIE) of $SiO_2$ layer in $CHF_3/C_2F_6$ on the underlying Si surface have been studied by X-ray photoelectron spectroscopy (XPS), secondary ion mass spectrometer, Rutherford backscattering spectroscopy, and high resolution transmission electron microscopy. We found that two distinguishable modified layers are formed by RIE : (i) a uniform residue surface layer of 4 nm thickness composed entirely of carbon, fluorine, oxygen, and hydrogen with 9 different kinds of chemical bonds and (ii) a contaminated silicon layer of about 50 nm thickness with carbon and fluorine atoms without any observable crystalline defects. To search the removal condition of the silicon surface residue, we monitored the changes of surface compositions for the etched silicon after various post treatments as rapid thermal anneal, $O_2$, $NF_3$, $SF_6$, and $Cl_2$ plasma treatments. XPS analysis revealed that $NF_3$ treatment is most effective. With 10 seconds exposure to $NF_3$ plasma, the fluorocarbon residue film decomposes. The remained fluorine completely disappears after the following wet cleaning.

• 한국재료학회지
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• 제5권6호
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• pp.706-714
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• 1995

원거리 플라즈마 화학증착법을 이용하여 저온에서 이산화규소박막을 제조하였다. 본 연구 에서는 공정변수인 기판의 온도, 반응기체의 조성 및 분압과 플라즈마 전력에 따른 산화막의 재료적인 물성을 평가하였다. XPS결과에서 산화막은 양론비(O/Si=2)보다 약간 적어 실리콘이 많이 함유된 막으로 나타났다. 이 경우 굴절율과 ESR분석에 의해 미결합된 실리콘의 양이 증가함을 알 수 있었다. SIMS분석에 의해 미량의 질소성분이 계면에 존재하는 것과 실리콘 미결함을 관찰하였다. FT-IR로부터 막내 수소량을 정량화하였으며 결합각 분포는 20$0^{\circ}C$이상에서 열산화막과 비슷한 값을 얻었다. 하지만 열산화막에 비해 높은 식각율을 보여 계면 스트레스에 의해 막내의 결합력이 약해진 것으로 생각된다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.285-285
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• 2013

Recently, hexagonal boron nitride (h-BN), which is III-V compound of boron and nitride by strong covalent sp2 bonds has gained great interests as a 2 dimensional insulating material since it has honeycomb structure with like graphene with very small lattice mismatch (1.7%). Unlike graphene that is semi-metallic, h-BN has large band gap up to 6 eV while providing outstanding properties such as high thermal conductivity, mechanical strength, and good chemical stability. Because of these excellent properties, hBN can potentially be used for variety of applications such as dielectric layer, deep UV optoelectronic device, and protective transparent substrate. Low pressure and atmospheric pressure chemical vapor deposition (LPCVD and APCVD) methods have been investigated to synthesize h-BN by using ammonia borane as a precursor. Ammonia borane decomposes to polyiminoborane (BHNH), hydrogen, and borazine. The produced borazine gas is a key material that is a used for the synthesis of h-BN, therefore controlling the condition of decomposed products from ammonia borane is very important. In this paper, we optimize the decomposition of ammonia borane by investigating temperature, amount of precursor, and other parameters to fabricate high quality monolayer h-BN. Synthesized h-BN is characterized by Raman spectroscopy and its absorbance is measured with UV spectrophotometer. Topological variations of the samples are analyzed by atomic force microscopy. Scanning electron microscopy and Scanning transmission Electron microscopy are used for imaging and analysis of structures and surface morphologies.

• 패션비즈니스
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• 제14권6호
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• pp.39-52
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• 2010

Interests in creating three-dimensionally designed fabric materials are growing rapidly in the sectors of the fashionable textiles with the creativity, new functions, and aesthetics. A number of finishing methods have been developed and proposed to add or create new functions and designs for silk fabrics. Due to the strong hydrogen bonds between the molecules of silk fibroins, the thermal treatment methods used in thermoplastic fiber processing, which can easily deform the synthetic filament fabrics to endow three-dimensional appearance to the fabrics, are not applicable to the silk fabric treatment. In order to modify the fine structure of silk fiber, neutral salt solution treatment methods have been suggested. In this study, the effect of the calcium nitrate solution on the physical and mechanical properties of silk fabrics was investigated by using the KES(Kawabata Evaluation System) equipment. Based on these findings, relationships between parameters, for example, the thickness and the compressional energy, the thickness and the compressional linearity, and the air permeability and the pore area statistical analysis were investigated. The relationships between the process parameters such as treatment temperature/time and the resulting fabric property parameters were also analyzed by using several SAS procedures.

• 생체재료학회지
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• 제22권4호
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• pp.235-248
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• 2018

Background: Injectable hydrogels have been extensively researched for the use as scaffolds or as carriers of therapeutic agents such as drugs, cells, proteins, and bioactive molecules in the treatment of diseases and cancers and the repair and regeneration of tissues. It is because they have the injectability with minimal invasiveness and usability for irregularly shaped sites, in addition to typical advantages of conventional hydrogels such as biocompatibility, permeability to oxygen and nutrient, properties similar to the characteristics of the native extracellular matrix, and porous structure allowing therapeutic agents to be loaded. Main body: In this article, recent studies of injectable hydrogel systems applicable for therapeutic agent delivery, disease/cancer therapy, and tissue engineering have reviewed in terms of the various factors physically and chemically contributing to sol-gel transition via which gels have been formed. The various factors are as follows: several different non-covalent interactions resulting in physical crosslinking (the electrostatic interactions (e.g., the ionic and hydrogen bonds), hydrophobic interactions, ${\pi}$-interactions, and van der Waals forces), in-situ chemical reactions inducing chemical crosslinking (the Diels Alder click reactions, Michael reactions, Schiff base reactions, or enzyme-or photo-mediated reactions), and external stimuli (temperatures, pHs, lights, electric/magnetic fields, ultrasounds, or biomolecular species (e.g., enzyme)). Finally, their applications with accompanying therapeutic agents and notable properties used were reviewed as well. Conclusion: Injectable hydrogels, of which network morphology and properties could be tuned, have shown to control the load and release of therapeutic agents, consequently producing significant therapeutic efficacy. Accordingly, they are believed to be successful and promising biomaterials as scaffolds and carriers of therapeutic agents for disease and cancer therapy and tissue engineering.

• 접착 및 계면
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• 제22권4호
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• pp.128-135
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• 2021

본 연구에서는 acid group을 포함하는 acid 폴리올을 합성하였고, acid 폴리올을 함량별로 도입하여 신규 폴리우레탄 접착제를 개발하였다. Acid 폴리올 도입하였을 때 acid content가 0.1~0.3 wt%일 때 기계적 물성이 최댓값을 나타냈으며, 0.5 wt% 이상의 함량에서는 기계적 물성 및 접착 강도가 감소하는 것을 확인하였다. Acid group으로는 carboxylic acid와 sulfuric acid를 도입하여 특성을 비교하였으며, carboxylic acid가 sulfuric acid보다 강한 수소 결합력을 보이며 기계적 물성을 향상시켰다. 또한, ZnO와 CaCO₃를 도입하여 입자의 크기와 물성의 상관관계를 확인하였다. ZnO와 CaCO₃를 도입한 경우 acid group과 이온결합이 형성되어 기계적 물성이 증가하는 것을 확인하였다.