• Journal of Electrical Engineering and Technology
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• v.1 no.2
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• pp.246-250
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• 2006

Highly ordered gold nanodot arrays have been successfully obtained by vacuum evaporation using an anodic aluminum oxide (AAO) as a shadow mask. An AAO mask with the thickness of 300 um was prepared through an anodization process. The structure of the nanodot arrays was studied by a field- emission scanning electron microscope (FE-SEM) equipped with an energy dispersive spectrometer (EDS). A tapping mode atomic force microscope (AFM) was employed for studies of height and phase feature. The nanodot arrays were precisely reproduced corresponding to the hexagonal structure of the AAO mask in a large area. In the gold nanodot arrays, the average diameter of dots is approximately the same as the AAO pore size in the range from 70 um to 80 nm and 100 nm center-to-center spacing. EDS analysis indicated that the gold dots were almost entirely consisted of gold, a highly demanded material.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.170-170
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• 1999

We studied Nb growth mode on Cu(100) surface by scanning tunneling microscopy (STM) at room temperature. Nb/Cu is immiscible at room temperature and thus is an ideal system for studying surface alloy formation. Initially deposited Nb atoms are incorporated subsurface on Cu(100). After annealing, they are preferentially found at step edges and appear as bright dots surrounded by dark rings. Ordering emerges from step edges as annealed. Ordered ({{{{ SQRT { 5} }$\times${{{{ SQRT { 5} }}}})R 26.6$^{\circ}$phase Nb structure is formed at $\theta$<0.2ML after annealing to 50$0^{\circ}C$. At higher coverage, $\theta$>0.25, annealing leads to p(2$\times$2) phase. due to large mismatch in lattice parameters, the domain is limited to a few tens of nm2. Growth kinetics of the system will be discussed.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.173-173
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• 1999

The initial growth mode of Nb on Ag(110) in sub-monolayer region is studied using Scanning Tunneling microscopy. E-beam evaporated Nb is deposited onto the substrate at RT, and STM measurements are carried out at RT and 78K. With Nb being immiscible in bulk Ag, 3D islands formation begins at early stage and no particular ordered structure is found. At very low coverages, however, many interesting phenomena are observed in association with Nb clusters. Small Nb clusters as deposited displays very strong size dependence against atom-manipulation by the STM tip. In addition, the apparent corrugation of clusters below the critical size exhibits dramatic dependence on the imaging bias, disappearing completely over a wide range of the bias. Possible physical mechanism responsible for such behavior will be discussed.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.9
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• pp.801-806
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• 2003

In recent years, there has been large interest in the fabrication of the self organized nanoscale structures since not only their potential utilization in electronic, optoelectronic, and magnetic devices but also their fundamental interest such as uniformity and regularization. An attractive candidate of these materials is anodic porous alumina film(Al$_2$O$_3$) which is formed by the anodization of aluminum in an appropriate acid solution. In this study to fabricate the porous alumina film with very uniform and nearly parallel pores the anodization was carried out under constant voltage mode in 0.3M oxalic acid as an electrolyte. The hexagonally ordered arrays with a few $\mu\textrm{m}$ in size two-dimensional polycrystalline structure were obtained of which pore densities were 1.1${\times}$10$\^$10//$\textrm{cm}^2$.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.140-140
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• 2000

The initial growth mode of Nb on Ag(11) in sub-monolayer regime and the influence of subsequent 520K annealing are studied using UHV Scanning Tunneling Microscopy. E-beam evaporated Nb is deposited onto the substrate at RT, and STM measurements are carried out at RT and 78 K. With Nb being immiscible in bulk Ag, 3D islands formation begins at early stage and no particular ordered structure is found. After annealing to 520K, most of islands are disappeared from terrace. There exist 2 possibilities. : (1) Diffusion of Nb into the 2nd or 3rd layer of Ag substrate or (2) agglomeration of Nb on Ag at higher temperature. A model will be given to explain the evidence. In addition, we investigated the change of STM image according to bias voltage depending on island size. Possible physical mechanism responsible for such behavior together with interaction between Nb islands and reactive gases will be also discussed.

• International journal of advanced smart convergence
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• v.12 no.1
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• pp.76-81
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• 2023

Journaling file systems are widely used to keep file systems in a consistent state against crash situations. As traditional journaling file systems are designed for block I/O devices like hard disks, they are not efficient for emerging byte-addressable NVM (non-volatile memory) media. In this article, we present a new in-memory journaling file system for NVM that is different from traditional journaling file systems in two respects. First, our file system journals only modified portions of metadata instead of whole blocks based on the byte-addressable I/O feature of NVM. Second, our file system bypasses the heavy software I/O stack while journaling by making use of an in-memory file system interface. Measurement studies using the IOzone benchmark show that the proposed file system performs 64.7% better than Ext4 on average.

• Journal of the Korea Society of Computer and Information
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• v.12 no.2 s.46
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• pp.123-130
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• 2007

The aim of this study was to propose a fusion and registration method with heterogeneous small animal acquisition system in small animal in-vivo study. After an intravenous injection of $^{18}F$-FDG through tail vain and 60 min delay for uptake, mouse was placed on an acryl plate with fiducial markers that were made for fusion between small animal PET (microPET R4, Concorde Microsystems, Knoxville TN) and Discovery LS CT images. The acquired emission list-mode data was sorted to temporally framed sinograms and reconstructed using FORE rebining and 2D-OSEM algorithms without correction of attenuation and scatter. After PET imaging, CT images were acquired by mean of a clinical PET/CT with high-resolution mode. The microPET and CT images were fusion and co-registered using the fiducial markers and segmented lung region in both data sets to perform a point-based rigid co-registration. This method improves the quantitative accuracy and interpretation of the tracer.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.171-171
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• 1999

We studied the charge redistribution in the Pt-M (M=Cu, Co) alloys by X-ray Absorption Near Edge Spectroscopy(XANES) and X-ray Photoelectron Spectroscopy(XPS). These analysis tools provide us information about the charge transfer in the valence band of intermetallic bonding. The samples were prepared by arc-melting method. After annealing this samples in vacuum for several hours, we cold get the ordered samples, which were confirmed with XRD analysis. the core and valence level energy shift in these system were investigated by Mg $K\alpha$(1253.6eV) x-ray source for Pt-Co alloys and monochromatized Al $K\alpha$ (1486.6eV) for Pt-Cu alloys. Pt L2, L3-edge, and Cu, Co K-edge XANES spectra were measured with the total electron-yield mode detector at the 3Cl beam line of the PLS (Pohang light source0. from the changes of White line (WL) area and the core level shifts of the each metal sites, we can obtain the information about the electrons participating in the intermetallic bonding of the Pt-Cu and Pt-Co alloys.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.554-554
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• 2000

To improve mechanical properties of Cu-Al-Ni alloy by the grain refinement, Cu-Al-Ni SMA ribbons were fabricated by melt spinning apparatus. The variations of microstructure, mechanical properties and transformation characteristics with the condition of rapid solidification and annealing time-temperature were investigated in Cu-Al-Ni SMA ribbons. The ribbons fabricated by melt spinning obtained around 1.5nm in width and 50-60${\mu}{\textrm}{m}$ in thickness. With increasing wheel speed in order of 10m/s, 15m/s, 20m/s, 30m/s and 3m/s, the grain size was decreased in order of 10${\mu}{\textrm}{m}$, 6.25${\mu}{\textrm}{m}$, 5.5${\mu}{\textrm}{m}$, 3${\mu}{\textrm}{m}$ and 3${\mu}{\textrm}{m}$. $M_{s}$ and $A_{s}$ temperature were decreased with decreasing grain size. By X-ray diffraction test, ordered $\beta$$_1$ phase was observed in all the SMA ribbons and the volume friction of it was increased with increasing wheel speed. With increasing wheel speed, strain was increased from 4.2% to 5.8% and fracture mode has changed from mixture of intergranular and dimple fracture to mixture of fiber structure and dimple fracture. The grain size of ribbon heat-treated at $600^{\circ}C$ was increased with increasing time. In the heat-treated ribbons at 55$0^{\circ}C$, ${\gamma}$$_2$ phases were observed.d.d.

• Journal of Technologic Dentistry
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• v.20 no.1
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• pp.37-49
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• 1998

The specimens used were Ag-25 Pd-15 Cu ternary alloy and Au addition alloy. These alloys were melted and casted by induction electric furnace and centrifugal casting machine in Ar atmosphere. These specimens were solution treated for 2hr at $800^{\circ}C$ and were then quenched into iced water, and aged at $350{\sim}550^{\circ}C$ Age- hardening characteristics of the small Au-containing Ag-Pd-Cu dental alloys were investigated by means of hardness testing. X-ray diffraction and electron microscope observations, electrical resistance, ergy dispersed spectra and electron probe microanalysis. Principal results are as follows : Hardening occured in two stages, i.e., stage I in low temperature and stage II in high temperature regions, during continuous aging. The case of hardening in stage I was due to the formation of the $L1_0$ type face-centered tetragonal PdCu-ordered phase in the grain interior and hardening in stage I was affected by the Cu concentration. In stage II, decomposition of the ${\alpha}$ solid solution to a PdCu ordered phase($L1_0$ type) and an Ag-rich ${\alpha}2$ phase occurred and a discontinuous precipitation occurred at the grain boundary. From the electron microscope study, it was conclued that the cause of age-hardening in this alloy is the precipitation of the PdCu ordered phase, which has AuCu I type face-centered tetragonal structure. Precipetation procedure was ${\alpha}{\to}{\alpha}+{\alpha}_2+PdCu {\to}{\alpha}_1+{\alpha}_2+PdCu$ at Pd/Cu = 1.7 Ag-Pd-Cu alloy is more effective dental alloy as ageing treatment and is suitable to isothermal ageing at $450^{\circ}C$.