• 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.

• 한국세라믹학회지
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• 제27권7호
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• pp.869-876
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• 1990

Hexagonal boron nitride was synthesized from boron oxide and sodium amide in ammonia gas stream. The reaction mechanisms and characteristics of as synthesized boron nitride was investigated by means of TG, DTA, IR, XRD, SEM and PSA. The results are ; 1) hexagonal boron nitride was synthesized from reactions at temperatures above 40$0^{\circ}C$ 2) Sodium metaborate was present as by-product after reaction so that the reaction mechanism is reduced as follows : 2B2O3＋3NaNH2longrightarrowBN＋3NaBO2＋2NH3. 3) boron nitride obtained at the reaction temperature below 40$0^{\circ}C$ is found to have random layer strudcture but the structure transits to ordered layer structure rapidly with increasing reaction temperature, showing separation of (101) differaction line from (10)band in XRD pattern of the reaction product at 50$0^{\circ}C$.

• BMB Reports
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• 제35권6호
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• pp.590-594
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• 2002

To elucidate the effect of gamma-irradiation on the molecular properties of myoglobin, the secondary and tertiary structures, as well as the molecular weight size of the protein, were examined after irradiation at various irradiation doses. Gamma-irradiation of myoglobin solutions caused the disruption of the ordered structure of the protein molecules, as well as degradation, cross-linking, and aggregation of the polypeptide chains. A SDS-PAGE study indicated that irradiation caused initial fragmentation of the proteins and subsequent aggregation, due to cross-linking of the protein molecules. The effect of irradiation on the protein was more significant at lower protein concentrations. Ascorbic acid protected against the degradation and aggregation of proteins by scavenging oxygen radicals that are produced by irradiation. A circular dichroism study showed that an increase of the irradiation decreased the a-helical content of myoglobin with a concurrent increase of the aperiodic structure content. Fluorescence spectroscopy indicated that irradiation increased the emission intensity that was excited at 280 nm.

• Journal of applied mathematics & informatics
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• 제5권2호
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• pp.433-448
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• 1998

In this study we use inexact Newton-like methods to find solutions of nonlinear operator equations on Banach spaces with a convergence structure. Our technique involves the introduction of a generalized norm as an operator from a linear space into a par-tially ordered Banach space. In this way the metric properties of the examined problem can be analyzed more precisely. Moreover this approach allows us to derive from the same theorem on the one hand semi-local results of kantorovich-type and on the other hand 2global results based on monotonicity considerations. By imposing very general Lipschitz-like conditions on the operators involved on the other hand by choosing our operators appropriately we can find sharper error bounds on the distances involved than before. Furthermore we show that special cases of our results reduce to the corresponding ones already in the literature. Finally our results are used to solve integral equations that cannot be solved with existing methods.

• 한국세라믹학회지
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• 제48권6호
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• pp.625-629
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• 2011

In this study, we show that by anodization of Nb in NaF electrolytes microcone niobium oxide layers can be formed under a range of experimental conditions. It is found that a single NaF electrolyte leads to the formation of microcones. At 1 M NaF, 40 V, 1 h, well-ordered microcones were generated on Nb discs. XRD results show that the initially formed anodic oxide is amorphous, but an amorphous to crystalline transition occurs during anodization. For the formation of favorable microcones, it is considered that proper parameters such as electrolyte concentration, voltage, anodizing time are necessary according to the kind of electrolytes.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.191.1-191.1
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• 2014

Crystallization has become the most popular technique for the separation of enantiomers since the Pasteur's discovery. To investigate mechanism of crystallization of chiral molecules, it is necessary to study self-assembled structures on two-dimensional surface. Here, we have studied two-dimensional self-assembled structures of an unnatural amino acid, (S)-${\beta}$-methyl naphthalen-1-${\gamma}$-aminobutyric acid (${\gamma}^2$-1-naphthylalanine) on Au(111) surface at 150 K using scanning tunneling microscopy (STM). At initial stage, we found two chiral honeycomb structures which are counter-clockwise and clockwise configurations in one domain. The molecules are arranged around molecular vacancies, dark hole. By further increasing the amounts of adsorbed ${\gamma}^2$-1-naphthylalanine, a well-ordered square packed structure was observed. In addition, we found the other structure that molecules were trapped in the pore of the hexagonal molecular assembly.

• Preventive Nutrition and Food Science
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• 제7권2호
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• pp.184-187
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• 2002

Blood products from slaughterhouses that are not hygienically prepared for disposal or food consumption pose a human health hazard. Gamma irradiation is an effective method for sterilization of blood products, but may introduce changes in the molecular characteristics of proteins. This study evaluated the effects of irradiation on animal plasma proteins. Bovine and porcine blood was obtained from a slaughterhouse and the plasma proteins purified and lyophilized. The secondary structure and molecular weight distribution of the plasma protein solutions and powders were examined after ${\gamma}$-irradiation at 1, 5, 7 and 10 kGy. Gamma-irradiation affected the molecular properties of the protein solutions, but not the protein powders. Circular dichroism and sodium dodecyl sulfate-polyacrylamide gel electrophoresis studies showed that increased doses of ${\gamma}$-irradiation decrease the ordered structure of plasma proteins in solution, and cause initial fragmentation of the polypeptide chains and subsequent aggregation.

• 대한의용생체공학회:의공학회지
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• 제15권4호
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• pp.389-394
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• 1994

The age-hardening behavior and the structural changes in a commercial dental Au-Ag-Cu-Pd alloy were investigated by means of hardness test, optical and scanning electron microscopic observation, energy dispersive spectroscopy and X-ray diffraction study. The drastic reduction in hardness by prolonged aging occurred after a rapid increase in hardness at the initial stage by the isothermal aging at $350^{\circ}C$. This softening was due to the broad precipitates formation of the lamellar structure which was composed of the f.c.t. AuCu I ordered f.c.t. phase containing Pd and the f.c.c. Ag-rich $\alpha$1 solid solution f.c.c.phase containing Au.

• 센서학회지
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• 제27권1호
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• pp.36-39
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• 2018

Transparent olivine $LiNiPO_4$ thin films on sapphire substrates were fabricated by radio frequency (RF) magnetron sputtering. The X-ray diffraction patterns show these thin films have the phase of $LiNiPO_4$ with an ordered olivine structure indexed to the orthorhombic Pmna space group. $LiNiPO_4$ thin films deposited on sapphire substrates exhibit transmittance of about 83 %. It was confirmed that the $LiNiPO_4$ thin film exhibits a high potential of 5 V-class.

• 한국신뢰성학회:학술대회논문집
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• 한국신뢰성학회 2004년도 정기학술대회
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• pp.201-206
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• 2004

The linear consecutive-k-out-of-n:F system consists of n components ordered linearly and fails if and only if at least k consecutive components fail. We assume that the failure times of components are independent and identical exponentially distributed. This paper develops a model to calculate the expected cost per unit time of a linear consecutive-k-out-of-n:F system. The optimization problem to find the system structure parameter k to minimize the expected cost per unit time is considered.