• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.55-55
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• 2010

We use ab initio density functional theory to determine the effect of bundling on the equilibrium structure, electronic and magnetic properties of $Mo_6S_{9-x}I_x$nanowires with x = 0, 3, 4.5, 6. Each unit cell of these systems contains two $Mo_6S_{6-x}I_x$ clusters connected by S3 linkages to form an ordered linear array. Due to the bi-stability of the sulfur linkages, the total energy of the nanowires exhibits typically many minima as a function of the wire length. We find that nanowires can switch over from metallic to semiconducting by applying axial stress. Structural order is expected in bundles with x=0 and x=6, since there is no disorder in the decoration of the Mo clusters. In bundles with other stoichiometries, we expect structural disorder to occur. We find the optimum inter-wire distance to depend sensitively on the orientation of the wires, but only weakly on x. It is also found that the electronic properties of nanowires are affected strongly due to bundling of nanowires exhibiting very unusual Fermi surfaces. Furthermore, ferromagnetic behaviors are observed in selected stable and many more unstable atomic arrangements in nanowire bundles.

• Bulletin of the Korean Chemical Society
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• 제10권1호
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• pp.50-57
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• 1989

A pressure effect of the dehydrogenation of ethylalcohol catalyzed by alcoholdehydrogenase was observed in Tris-HCl buffer, pH 8.8 from $25^{\circ}C$ to $35^{\circ}C$ under high pressure system by using our new theory. The theory makes it possible for us to obtain all rate and equilibrium constants for each step of all enzymatic reaction with a single intermediate. We had enthalpy and volume profiles of the dehydrogenation to suggest a detail and reasonable mechanism of the reaction. In these profiles, both enthalpy and entropy of the reaction are positive and their values decrease with enhancing pressure. It means that the first step is endothermic reaction, and its strength decrease with elevating pressure. At the same time, all activation entropies have large negative values, which prove that not only a ternary complex has a more ordered structure at transition state, but also water molecules make a iceberg close by the activated complex. In addition to this fact, the first and second step equilibrium states are controlled by enthalpy. The first step kinetic state is controlled by enthalpy but the second step kinetic state is controlled by entropy.

• 대한조선학회 특별논문집
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• 대한조선학회 2015년도 특별논문집
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• pp.34-40
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• 2015

The design, procurement and fabrication of FPSO project ordered by Inpex Browse, Ltd. have been currently carried out by DSME(Daewoo Shipbuilding Marine and Engineering Co.). The unit will be installed and operated in the Ichthys field offshore of North-Western Australia and there are the particular design requirements to do with performance on the environment loads corresponding to max. 10,000 years return period wave. Also, the operational life of FPSO has to be over 40 years. With this background, this paper introduces the structural design procedure of crane pedestal foundation operated in north-western Australia offshore. The design of crane pedestal foundation structure is basically based on international design code (i.e. API Spec. 2C), Classification society's rule and project specifications. The design load cases are mainly divided into the crane normal operating conditions and crane stowed conditions according to environment conditions of the offshore with 1-year, 5-year, 10-year, 200-year and 10,000-year return period wave. This design experience for crane pedestal foundation operated in north-western Australia offshore will be useful to do engineering of other offshore crane structures.

• 한국자기학회지
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• 제17권3호
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• pp.137-140
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• 2007

레이저 간섭 석판 장비(Laser Interference Lithography; LIL)를 이용하여, Anodic Aluminum Oxide(AAO) 나노기공의 배열을 향상 시켰다. 이후 진공에서 Fe와 Cu를 AAO/Si에 성장하고, AAO를 제거하여 Cu/Fe(20 nm) 나노구조를 제작하였다. AAO의 나노기공과 나노구조는 전처리 과정에서 제작된 PR(photoresist) 나노선을 따라 1차원으로 배열되었다. 자성 나노구조의 자기이력곡선으로부터 이들이 vortex 구조를 가지며, 쌍극자 상호작용이 지배적임을 확인하였다.

• 한국표면공학회지
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• 제51권6호
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• pp.387-392
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• 2018

Nanopatterning is one of the essential nanotechnologies to fabricate electronic and energy nanodevices. Therefore, many research group members made a lot of efforts to develop simple and useful nanopatterning methods to obtain highly ordered nanostructures with functionality. In this study, in order to achieve pattern formation of three-dimensional (3D) hierarchical nanostructures, we introduce a simple and useful patterning method (nano-transfer printing (n-TP) process) consisting of various linewidths for diverse materials. Pt and $WO_3$ hybrid line structures were successfully stacked on a flexible polyimide substrate as a multi-layered hybrid 3D pattern of Pt/WO3/Pt with line-widths of $1{\mu}m$, $1{\mu}m$ and 250 nm, respectively. This simple approach suggests how to fabricate multiscale hybrid nanostructures composed of multiple materials. In addition, functional hybrid nanostructures can be expected to be applicable to various next-generation electronic devices, such as nonvolatile memories and energy harvesters.

• International Journal of Internet, Broadcasting and Communication
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• 제14권2호
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• pp.89-97
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• 2022

The growth of online market is accelerating due to the development of technology and the era of pandemic. In order to deliver the ordered product to customers courier service should be used. In addition, the courier logistics market is growing with the growth of the online market. With the growth of the logistics market, traffic and environmental problems are emerging as social issues. Logistics technology of urban community logistics courier terminal system utilizing vacant space in the city has been developed as a new alternative to environment and traffic problems by increasing logistics efficiency in the city area. In this study, we propose a concept of a system that performs operational concept definition and scenario analysis by applying model-based perspective analysis to urban community logistics courier terminal system under development. Through this study, we defined the operating concept of the urban community logistics courier terminal, which is the target of development, and defined the scenario for system operation by grasping the structure and function of the system and applied it to system development.

• 한국진공학회지
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• 제6권S1호
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• pp.53-58
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• 1997

It is well known that the equiatomic FeAl alloy crystallizes in a paramagnetic CsCl structure and is very stable in a wide temperature range owing to a significant charge transfer from Al to Fe. A presence of structural defects normally enhances the magnetic and magneto-optical properties of this alloy. In this study spin-resolved photoemission and magnetic circular dichroism (MCD) were carried out on both ordered and disordered $Fe_{0.52}Al_{0.48}$ alloy films. The disordered state in the alloy films was obtained by a vapor quenching deposition on cooled substrates. It is shown that the order-disorder transition in the Fe0.52Al0.48 alloy films leads to a significant change in the spin polarization. Form the MCD results the orbital and spin magnetic moments of the constituent atoms are obtained. According to the sum rule the spin and orbital magnetic moments of Fe in the disordered FeAl film are $\mu\frac{SR}{spin}=0.8\mu_B$ and $\mu\frac{SR}{orb}=0.14\mu_B$ respectively. The spin magnetic moment is also evaluated to be $\mu\frac{BR}{spin}=0.77\mu_B$ by the branching ration method employing a photon polarization of 90%.

• Journal of Photoscience
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• 제9권2호
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• pp.66-69
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• 2002

Zinc chlorin 1 possessing tertiary 3$^1$_hydroxy and 13$^1$-oxo groups was synthesized as a model for the antenna chlorophylls of photosynthetic green bacteria. Self-aggregation of 1 in nonpolar organic solvents was examined and compared to 2 and 3 possessing a secondary and primary 3$^1$_hydroxy group, respectively. Zinc chlorin 1 self-aggregated in I％(v/v) CH$_2$Cl$_2$-hexane to form oligomers and showed a red-shifted Qy maximum at 704 nm compared to the monomer (648 nm in CH$_2$CI2$_2$). This red-shift is larger than that of 3$^1$S-2 (648 to 697 nm) and comparable to that of3$^1$R-2 (648 to 705 nm), but smaller than that of 1 (648 to 740 nm), indicating that while a single 3$^1$-methyl group (primary to secondary OH) suppressed tight and/or extended aggregation, the additional 3$^1$-methyl group (secondary to tertiary OH) did not further suppress aggregation. The relative stability of the aggregates was in the order 3> 3$^1$R-2∼ 1 > 3$^1$S-2 as determined by visible spectral analyses. Molecular modeling calculations on oligomers of zinc chlorins 1, 3$^1$ R-2 and 3 gave similar well-ordered energy-minimized structures, while 3 stacked more tightly than 3$^1$ R- 2 and 1. In contrast, 3$^1$S-2 gave a relatively disordered (twisted) structure. The calculated oligomeric structures could explain the visible spectral data of 1-3 in nonpolar organic solvents. Moreover, self- aggregation of synthetic zinc 13$^1$_oxo-hlorins 4-6 possessing a 2-hydroxyethyl, 3-hydroxypropyl and 3- hydroxy-I-propenyl group at the 3-position in nonpolar organic solvents was discussed.

• 보존과학연구
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• 통권22호
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• pp.115-132
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• 2001

No. 3 Tomb of Bogam-ri, in Naju City, Chollanam-do Province, was a site excavated and inspected from 1996 to 1998 and had a various grave forms, including jar-coffins, stone-chambers and stone-cists. Although most of the metal artifacts excavated from it were severely corroded, we could implement microstructure investigation by collecting samples from the iron axes, iron coffin-nails and iron clamps in which the metal parts were remained. The metal structures were inspected by using metallographic microscope and SEM, and fine components analysis was implemented by ICP. To examine the hardness differences in accordance with the structure distribution, we measured the hardness by structures with Vickers hardness testing machine. As a result of the metal structure inspection, most of them were pure iron, ferrite, and also pearlite, cementite and widmannstaten structures were displayed. We could confirm carbonization was formed on the surface of the iron axes-B, iron coffin-nails-B, and iron clamps-A. There was no carbonization in the rest of the artifacts, and it is not certain that whether the carbonized parts were peeled off through extreme corrosion or they were not carbonized when they were made. In the particular part of a blade, the quality of the material was strengthened through processing. Due to the processing re-grain was caused and fine grain particles were formed. As a result of the ICP component analysis, there were no addition atoms because pure irons were used as materials. In the mean time, No. 17 jar-coffin where the iron axes-A are excavated, is chronologically ordered as from the late-fourth century to the mid-fifth century, and No. 1 and No. 2 stone chambers, where the rest of the artifacts were excavated, as the early-sixth century. It was difficult to relate the periodic differences with the manufacture technique artifacts which we inspected because there were no distinct characteristics of the manufacture technique of the metal structures and it is impossible to conclude the artifacts and sites are at the same period although their periods are different.

• 한국자기학회지
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• 제19권5호
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• pp.171-175
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• 2009

Ir(001) 표면 위에 얹혀진 철 단층의 자성을 제일원리 전자구조 계산방법을 이용하여 이론적으로 탐구하였다. 비교를 위하여 Fe와 Ir이 규칙적으로 반반 섞인 위층에 대하여도 계산하였다. 모두 Fe로 이루어진 단층의 경우 철원자의 자기모멘트는 2.95 보어마그네톤으로 비교적 큰 값을 가졌으며, Fe와 Ir이 반반 섞인 위층에서 Fe의 자기모멘트는 2.83 보어마그네톤이었다. 이러한 자성과 전자구조의 자세한 면은 계산된 상태밀도와 스핀밀도를 통하여 논의한다. 각 위층 원자의 평형위치를 구하기 위해 총에너지와 원자힘 계산을 하였다. 그 결과 Fe 위층에서의 Fe 원자위치가 Fe와 Ir이 반반 섞인 위층의 Fe 위치보다 Ir 기판에 다소 가까웠다.