• 공업화학
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• 제32권1호
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• pp.10-14
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• 2021

DsRed에서 유래한 적색 형광 단백질들 중 하나인 mCherry는 GFP와 유사한 3차 구조를 가진 잘 알려진 적색 형광 단백질 중 하나이며, 수소결합 네트워크를 형성하고 있지 않아서 pH 변화에 민감하지 않다. 반면 mCherry의 발색단 근처에서 돌연변이를 야기 시켜 만든 mCherry-I202T는 mCherry 단백질의 202번째 아미노산인 이소루신(Ile)을 트레오닌(Thr)으로 치환함으로써 모체와는 다르게 추가적인 수소결합을 형성하여, 주위 pH에 더욱 민감하게 반응할 뿐 아니라 적색 편이된 형광을 보였다. 수소결합이 확장된 I202T의 pH 민감성을 검증하기 위해 산성과 염기성 pH 범위에서 I202T의 UV-vis 흡광 스펙트럼 변화와 가역성을 확인하고, 그를 pH sensor에 적용 가능한지 그 가능성을 검증하고자 하였다.

• 한국자기공명학회논문지
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• 제11권2호
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• pp.64-72
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• 2007

[ $^1H$ ] nuclear magnetic resonance (NMR) experiments have been performed at 30 - 300 K and 7 T to investigate dynamics of hydrogen bond network in the single crystal $(NH_4)_3H(SO_4)_2$. The two proton sites, ammonium proton and hydrogen-bond proton, are identified from the $^1H$ NMR MAS spectrum at 340 K. As temperature decreases, the $^1H$ NMR spectrum shifts to the higher frequency side with a larger linewidth. The spectrum at 65 K shows a distinctive change in line shape toward the ferroelectric transition at 63 K. The measured values of $T_1$ for ammonium and hydrogen-bond protons are similar in the whole range of temperature. $T_1$ of $^1H$ NMR shows a gradual decrease down to 120 K and starts to steeply increase below 100 K. Then $T_1$ shows abrupt decrease below 70 K with a sharp minimum at 63 K, where the ferroelectric transition occurs. This temperature dependence of spectrum and $T_1$ clearly prove that the large change in the dynamics of hydrogen bond network is associated with the ferroelectric phase transition at 63 K.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 1996년도 추계학술대회발표논문집; 고려대학교, 서울; 26 Oct. 1996
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• pp.19-22
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• 1996

A traditional approach to the prediction of economic and financial variables takes the form of statistical models to summarize past observations and to project them into the envisioned future. Over the past decade, an increasing number of organizations has turned to the use of neural networks. To date, however, many spheres of interest still lack a systematic evaluation of the statistical and neural approaches. One of these lies in the prediction of corporate bond yields for Korea. This paper reports on a comparative evaluation of ARIMA models and neural networks in the context of interest rate prediction. An additional experiment relates to an integration of the two methods. More specifically, the statistical model serves as a filter by providing estimtes which are then used as input into the neural network models.

• Bulletin of the Korean Chemical Society
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• 제7권5호
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• pp.331-334
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• 1986

The crystal structure of thiamin tetrahydrofurfuryl disulfide, one of the ring-opened derivatives of thiamin, has been determined by the X-ray diffraction methods. The crystal is monoclinic with cell dimensions of a = 8.704 (1), b = 11.207 (2), c = 21.260 (3) ${\AA}$ and ${\beta}$ = 92.44 (2)$^{circ}$, space group P2$_{1}$/c and Z = 4. The structure was solved by direct methods and refined to R = 0.076 for 1252 observed reflections measured on a diffractometer. The molecule assumes a folded conformation in which the pyrimidine and the tetrahydrofurfuryl rings are on the same side of the ethylenic plane. The pyrimidinyl, N-formyl and ethylenic planes are mutually perpendicular to each other and the N(3)-C(4) bond retains a single bond character. The structure is stabilized by an intramolecular N(4'${\alpha})-H{\cdots}O(2{\alpha}$) hydrogen bond. The molecules are connected via N(4'${\alpha}$)-H{\cdots}(N3')$ and O(5${\gamma})-H{\cdots}(N1')$ hydrogen bonds, forming a two-dimensional hydrogen-bonding network. The tetrahydrofurfuryl ring is dynamically disordered. The overall conformation as well as the packing mode is very similar to that of thiamin propyl disulfide.

• 대한화학회지
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• 제57권6호
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• pp.721-725
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• 2013

Reaction between 2-pyridinecarboxylic acid (Hpic) and $K_3[Cr(O_2)_4]$ give complex $[Cr(pic)_3].H_2O$ (1) which is characterized by elemental analysis and spectroscopic methods (FT-IR, Raman) and X-ray crystallography. In the crystal structure of 1, chromium atom with coordinated by three nitrogen and three oxygen atoms has a distorted octahedral geometry. Also a water molecule is incorporated in crystal network. Each water molecule acts as hydrogen bond bridging and connects two adjacent complexes by two $O-H{\cdots}O$ hydrogen bonds.

• Bulletin of the Korean Chemical Society
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• 제34권12호
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• pp.3591-3596
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• 2013

The enantioselective aza-Morita Baylis Hillman reaction of nitroalkene and N-tosylimine catalyzed by thiourea-tertiary amine has been investigated using density functional theory. Enantioselectivity is dominated by the cooperative effect of non-covalent and weak covalent interactions imposed by different units of catalyst. As Lewis base, the tertiary amine unit activates nitroalkene via weak covalent bond. The weak covalent interaction orients the reaction in a major path with smaller variations of this bond. The aromatic ring unit activates N-tosylimine via ${\pi}-{\pi}$ stacking. The non-covalent interaction selects the major path with smaller changes of the efficient packing areas. Thiourea unit donates more compact H-bonded network for species of the major path. The calculated ee value in xylene solution phase (97.6%) is much higher than that in N,N-Dimethylformamide (27.2%). Our conclusion is also supported by NBO analysis.

• 분석과학
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• 제15권3호
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• pp.317-320
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• 2002

The layer structure of the title compound, $[Ni(en)_2(H_2O)_2](CH_3C_6H_4SO_3)_2(H_2O)$ (en = ethylenediamine), consists of discrete cations, anions, and solvate water molecules linked by a hydrogen bonding network. The central Ni atom of the cation layer has a slightly distorted octahedral coordination geometry with the ethylenediamine ligands functioning as a N,N'-bidentate and the water ligands bonding through oxygen in a trans arrangement. The p-toluenesulfonate of the anion layer has an alternate sulfonate group directed toward opposite side of the cation layer. This layer structure is stabilized by a hydrogen bond involving the O atoms of the sulfonate, the water ligand, solvate water molecule, and the N atoms of the ethylenediamine.

• 대한화학회지
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• 제47권4호
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• pp.334-338
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• 2003

$[Co(phen)_2(Cl)(H_2O)] Clㆍ2H_2O$(phen=1,10-phenanthroline)의 결정구조는 X-ray에 의하여 결정되었다. 그 결정은 a=9.662(2), b=11.445(1), c=13.037(2)${\AA}$ ${\alpha}$=64.02(1), ${\beta}$=86.364(9), ${\gamma}=78.58(2)^°$ 그리고 Z=2의 격자인자를 갖는 triclinic계와 space group이 P1의 구조로 결정화 되었다. 배위된 양이온은 두개의 Phen 리간드, 하나의 chloride이온과 하나의 $H_2O$ 리간드가 cis 배열로 킬레이크된 6배위 코발트 원자가 포함된다. 코발트에 배위된 chloride에 더해서, 결정구조를 이루는 하나의 chloride이온과 네개의 물분자가 있다. 고체상태에서, 제목의 화합물은 수소결합을 통하여 3차원 그물구조를 갖는다.

• 대한화학회지
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• 제18권5호
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• pp.329-340
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• 1974

X-선 회절법을 이용하여 sulfadiazine, $C_{10}H_{10}N_4O_2S$, 의 결정 및 분자 구조를 규명하였다. Acetone 과 ethanol의 혼합용액으로 부터 얻은 결정은 일사축계에 속하며, 단위세포에는 4분자가 있고, 공간군은 P21/c이다. 단위세포 상수는 $a=13.71{\pm}0.04,\;b=5.84{\pm}0.03,\;c=15.11{\pm}0.05{\AA},\;{\beta}=115.0{\pm}0.3^{\circ}$이다. 결정구조는 3차원적인 와이센버그사진으로 부터 얻어진 실험치를 이용하여 패터슨합성과 프리에합성을 하고 이를 해석하여 밝혀냈다. 수소원자를 제외한 원자들의 좌표치는 최소자승법으로 정밀화 하였으며, 최종 R값은 관측된 1517개의 독립반사에 대하여 0.15이다. 벤젠고리와 피리미딘고리의 두 평면이 이루는 각은 $76^{\circ}$이고, S-N(1)결합을 중심으로 한 N(1)-C(1) 결합과 S-C(5)결합이 이루는 conformational angle은 $77^{\circ}$로서 gauche형을 하고 있다. 이미노기의 질소원자, N(1)은 대칭중심에 의하여 옮겨지는 다른 분자의 피리미딘고리의 질소원자, N(3)와 $N-H{\cdots}N$형의 수소결합을 이루고 있으며, 아미노기의 질소원자, N(4)는 b축의 거리만큼 떨어져 있는 다른분자의 산소원자, O(1) 및 O(2)와 두개의 $N-H{\cdots}O$형 수소결합을 이루고 있다. 이들 수소결합의 2차원적 그물은 (100)면에 평행한 무한한 분자층을 형성하며 인접분자층 사이에는 van der Waals의 힘에 의하여 결합되어 있다

• Bulletin of the Korean Chemical Society
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• 제33권6호
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• pp.2028-2030
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• 2012

The single-crystal structure of $CaCl_2{\cdot}2C_6H_{12}O_6{\cdot}3H_2O$ was determined with Mr=525.34, a=16.054(7) ${\AA}$, b=7.864(4) ${\AA}$, c=10.909(5) ${\AA}$, ${\beta}=127.894(8)^{\circ}$, V=1086.9(9) ${\AA}^3$, C2, Z=2 and $R$=0.0227 for 1727 observed reflections. The fructose moiety of the complex exists as a ${\beta}$-D-pyranose. The calcium ion is surrounded by eight oxygen atoms, These are arranged in symmetry-related pairs derived from four sugar and two water molecules. Three nonvicinal hydroxyl groups of fructose are involved in calcium binding. All the hydroxyl groups and water molecules are involved in forming an extensive hydrogen-bond network.