• 한국결정학회지
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• 제3권1호
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• pp.53-66
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• 1992

Extensive research has been perform성 on the property-microstructure-process condition relations of thin films. The various proposed models are mainly based on physical vapor deposition processes. Especially the study on the surface condition of substrates in Zone 1 with low surface mobility has not been sufficient. In this study, therefore, we discussed the mochological changes of TiN films deposited by plusma enhanced chemical vapor deposition process with substrates of different composition and micro-rorghness, and compared it with the Structure Zone Model. We could find out that the growth rate of films increased and micro-grain size decreased with the increase in micro-roughness, but it does not improve the mechanical properties because of many imperfections like voids, micro-cracks, stacking faults, etc. This means that, in these deposition conditions, the increase in shadowing diffect is more effective than the increase in nucleation sites on the growth of films due to the increase in substrate roughness.

• 한국자기공명학회논문지
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• 제2권2호
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• pp.131-140
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• 1998

The calcium-induced structural changes in the skeletal muscle regulatory protein troponin C (NTnC) involve a transition from a ‘closed’to an ‘open’structure with the concomitant exposure of a large hydrophobic interaction site for target proteins. Structural studies have served to define this conformational change and elucidate the mechanism of the linkage between calcium binding and the induced structural changes. There are now several structures of NTnC available from both NMR and X-ray crystallography. Comparison of the calcium bound structures reveals differences in the level of opening. We have considered the concept of a flexible open state of NTnC as a possible explanation for this apparent discrepancy. We also present simulations of the closed-to-open transition which are in agreement with the flexibility concept and with experimental energetics data.

• 통합자연과학논문집
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• 제8권4호
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• pp.250-257
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• 2015

The crystal structure of the potential active 3-(4-ethylphenyl)-3H-chromeno[4,3-c]isoxazole-3a(4H)-carbonitrile ($C_{19}H_{16}N_2O_2$) has been determined from single crystal X-ray diffraction data. In the title compound crystallizes in the monoclinic space group $P2_1/c$ with unit cell dimension a=6.6869 (8) ${\AA}$, b=15.8326 (19) ${\AA}$ and c= 15.237 (2) ${\AA}$ [${\alpha}=90^{\circ}$, ${\beta}=100.663^{\circ}$ and ${\gamma}=90^{\circ}$]. In the structure chromene, isoxazole and carboxylate are almost coplanar each other. All geometrical parameters revelled that chromene ring of pyran ring adopt sofa conformation. The crystal packing is stabilized by intermolecular C-H...N and C-H...O hydrogen bond interaction.

• 전자공학회논문지B
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• 제31B권5호
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• pp.26-33
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• 1994

Phase retrieval is concerned with the reconstruction of a signal from its Fourier transform magnitude (or intensity), which arises in many areas such as X-ray crystallography, optics, astronomy, or digital signal processing. In such areas, the Fourier transform phase of the desired signal is lost while measuring Fourier transform magnitude (F.T.M.). However, if a reference 'signal is added to the desired signal, then, in the Fourier trans form magnitude of the added signal, the Fourier transform phase of the desired signal is encoded. This paper addresses uniqueness and retrieval of the encoded Fourier phase of a multidimensional signal from the Fourier transform magnitude of the added signal along with the Fourier transform magnitude of the desired signal and the information of the additive reference signal. In Part I, several conditions under which the desired signal can be uniquely specified from the two Fourier transform magnitudes and the additive reference signal are presented. In Part II, the development of non-iterative algorithms and an iterative algorithm that may be used to reconstruct the desired signal(s) is considered.

• 전자공학회논문지B
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• 제31B권5호
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• pp.34-41
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• 1994

Phase retrieval is concerned with the reconstruction of a signal from its Fourier transform magnitude (or intensity), which arises in many areas such as X-ray crystallography, optics, astronomy, or digital signal processing In such areas, the Fourier transform phase of the desired signal is lost while measuring Fourier transform magnitude (F.T.M.). However, if a reference 'signal is added to the desired signal, then, in the Fourier trans form magnitude of the added signal, the Fourier transform phase of the desired signal is encoded This paper addresses uniqueness and retrieval of the encoded Fourier phase of a multidimensional signal from the Fourier transform magnitude of the added signal along with Fourier transform magnitude of the desired signal and the information of the additive reference signal In Part I, several conditions under which the desired signal can be uniquely specified from the two Fourier transform magnitudes and the additive reference signal are presented In Part II, the development of non-iterative algorithms and an iterative algorithm that may be used to reconstruct the desired signal (s) is considered

• Bulletin of the Korean Chemical Society
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• 제34권3호
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• pp.773-776
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• 2013

We have prepared 1-D BiSI and 2-D BiOI nanostructures, and characterized them by scanning electron microscopy, transmission electron microscopy (TEM), X-ray diffraction crystallography, thermogravimetric analysis/differential scanning calorimetry, and UV-visible absorption. Here, we first report clear HR-TEM image of BiSI. In addition, we first found that the growth direction of BiSI is [12-1] plane, with the neighboring distance of 0.30 nm. The crystal structures of BiSI and BiOI are found to be orthorhombic (Pnam) and tetragonal (P4/nmm), respectively. The absorption band gaps of BiSI and BiOI are measured to be 1.55 and 1.92 eV, respectively. Our study could further highlight the applications of V-VI-VII compounds.

• 한국결정학회지
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• 제12권1호
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• pp.5-9
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• 2001

Nd/sub 0.05/Y/sub 0.95/Ca₄O(BO₃)₃(Nd:YCOB) single crystals were grown by the Czochralski method using a iridium crucible under N₂ atmosphere. Optimum growth parameters to get high quality of single crystals were 1.5∼2 mm/hr of growth rate and 10∼20 rpm of rotation rate. The grown crystals were transparent with light purple color and well-developed in cleavage planes. The crystal structure of Nd;YCOB were identified to monoclinic by XRD method. Crystal defects acting as light scattering centers, such as micro-pores, secondary phases, inclusions and cracks were not observed under the He-Ne laser illuminations. Three red, green, blue laser devices for the RGB laser oscillations were designed and then fabricated from the grown Nd:YCOB crystals according to the phase-matching angles of negative type-I which were φ=16.40°, 33.95° and θ=22.59° with the flatness of λ/6 at least, respectively.

• 한국결정학회지
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• 제12권1호
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• pp.20-24
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• 2001

NiZn-ferrite was synthesized usign waste iron oxide catalysts which were produced from styrene monomer process and buried underground as an industrial wastes. The spinel type ferrite was obtained by calcination and sintering of the mixture of finely ground waste catalysts, nickel oxide and zinc oxide powders. The sintered body of Ni/sub 0.5/Zn/sub 0.5/Fe₂O₄ composition at 1230℃ for 5 hours showed the density of 5.38g/㎤, and initial permeability of 59 at 1 kHz. Not only cerium oxide, which existed as a major component in the catalyst, but also unicorporated NiO and ZnO into spinel structure remained as second phases after sintering.

• 한국결정학회지
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• 제12권1호
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• pp.31-36
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• 2001

결정학의 핵심 과제는 위상(phase) 문제의 해결이다. 이 위상 묹를 해결하는 한 방법으로 요즘의 고속 컴퓨터를 사용하는 시행착오법(trial and error method)을 가상해 볼 수 있다. 간단한 예를 들면, centrosymmetric인 삼사정계(triclinic system)에 속한 비교적 작은 유기화합물인 경우, 전형적으로 3000개 정도의 회절 강도가 측정된다. Centrosymmetric 공간군(space group)의 구조 인자(structure factor)는 위상이 0°이거나 180°이기 때문에, 구조 인자는 "+"이거나 "-"부호를 가지므로 3000개 각각에 두 가지 부호를 배당할 수 있다. 이 3000개의 부호를 조합할 수 있는 개수는 2/sup 3000/개로 이 개수만큼의 Fourier 지도들을 작도하면 그 중의 하나는 옳은 것이다. Fourier 지도 한 개를 작도하는데 1분이 소요된다고 가정하면, 이들을 모두 계산하는데 2/sup 2981/년의 계산 시간이 소요된다. (참고로 2/sup 10/=1084). 따라서 시행착오법으로는 도저히 불가능함을 알 수 있다. 더구나, noncentrosymmetricc 공간군에서는 더욱 어렵게 된다. 그리하여 위상 문제를 해결하려는 많은 시도가 행해졌는데, 그것들 중의 하나가 Patterson 방법이다.

• 한국결정학회지
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• 제12권1호
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• pp.37-54
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• 2001

1960년대까지는 단결정 구조를 해석할 때 주로 Patterson 방법으로 중원자(heavy atom)를 찾고 이 중원자에 의한 위상에 기초하여 구조를 해석해 왔다. 회절점의 위상을 수학적으로 결정하는 직접법(direct method)은 1948년 Harker와 Kasper에 의해서 최초의 논문이 발표된 이후, 50∼60년 대에 이론적 기초가 구축되었으며, 70년대부터 컴퓨터 프로그램화되어 실용되기 시작하였다. 본 해설문에서는 직접법에 사용되는 정규화된 구조 인자(normalized structure factor)와 unitary 구조 인자의 정의를 소개한 후, 직접법의 기본식인 Sayre 방정식으로부터 유도되는 반전적 혹은 대칭중심적(centric)인 경우에서 성립하는 부호 관계(sign relationship) 및 ∑₂-관계(∑₂-relation)와 비반전적(acentric)경우에서 성립하는 탄젠트 공식(tangent formula)의 유도 과정을 설명하였고, 부호 관계와 탄젠트 공식이 필요로 하는 처음 몇 개의 회절점의 위상을 정하는 과정도 보였다.