• Proceedings of the Optical Society of Korea Conference
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• 2008.07a
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• pp.157-158
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• 2008

High-order harmonics from gaseous atoms driven by an intense femtosecond laser pulse can form an attosecond pulse train. By selecting suitable harmonic generation conditions, the harmonic spectrum can be broad enough to form sub-hundred attoseconds. One serious limitation, however, comes from the inherent attosecond chirp originating from the harmonic generation process. We have proposed to compensate for the positive attosecond chirp by making use of negative group delay dispersion of a metallic x-ray filter or a noble gas. We generated 241-as pulses from neon and compressed them to 106 as after propagating through argon, close to the transform-limited duration of 98 as.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.5
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• pp.453-458
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• 2011

We study the effect of mechanical machining and heat treatment on the surface residual stress of TP 316L stainless steel. Electrical discharge machining (EDM), milling and grinding were applied to TP 316L plate specimens. The residual stress and hardness were measured and the effect of heat treatment on the surface residual stress was examined. The residual stress was measured by the X-ray diffraction method, which showed that the surface residual stress was related only to the stress magnitude and was independent of the compressive or tensile component. The surface residual stress was greatly decreased by the heat treatment, but it was not removed completely.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.2092-2094
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• 2000

As a next generation lithography (NGL) technology for VLSI semiconductor fabrication, electron beam, ion beam, X-ray and extreme ultraviolet(EUV) are considered as possible candidates. Among these methods, EUV lithography(EUVL) is thought to be the most probable because it is easily realized by improving current optical lithography technology. In order to set EUV radiation which can be applied to EUVL, it is essential to generate very high density and high temperature plasma stably. The method using a pulse power laser and a high voltage pulse discharge is commonly used to accomplish such a high density and high temperature plasma. In this paper we review the recent trends of the EUV generation technique by high density and high temperature plasma.

• Korean Journal of Chemical Engineering
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• v.35 no.12
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• pp.2379-2383
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• 2018

We report a facile one-pot aqueous-phase synthesis of PdAu bimetallic nanoparticles with different Pd/Au ratio. The synthesis was conducted by co-reduction of Pd and Au precursor using ascorbic acid as a reducing agent and in the presence of polyallylamine hydrochloride (PAH). By high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM) and energy-dispersive X-ray spectrometry (EDS) analyses, we found that the synthesized nanoparticles had an onion-like core/shell/shell/shell structure with Au-rich core, Pd-rich shell, Au-rich shell, and Pd shell, respectively. We also investigated the catalytic performance of the synthesized PdAu nanoparticles toward hydrogen peroxide generation reaction.

• Proceedings of the Optical Society of Korea Conference
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• 2002.07a
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• pp.228-229
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• 2002

강한 세기의 레이저가 원자에 입사하여, 조사된 레이저 파장의 홀수 배에 해당하는 파장을 가진 빛이 여러 차수에 걸쳐 발생하는 것을 고차조화파(high-order harmonics)라고 한다. (1.2) 고차조화파를 이용하면 고가의 방사광 가속기로 발생시키는 연엑스선 영역의 빛을 작은 비용과 작은 규모의 장비로 발생시킬 수 있으므로 많은 주목을 받고 있다. 고차조화파는 기본적으로 원자의 공간적인 대칭성과 레이저 전기장의 시간적 주기성에 의해 홀수 차수에서 발생하게 된다. (중략)

• Proceedings of the Korean Nuclear Society Conference
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• 2005.05a
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• pp.1044-1045
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• 2005

• Journal of the Korean Graphic Arts Communication Society
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• v.9 no.1
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• pp.1-11
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• 1991

In this reseach, double-layered photoconductor consist of the carrier generation layer(CGL) of $\varepsilon$ type copper phthalocyanine thin film by an aqueous coating method and the carrier transport layer(CGL) of polyvinyl carbazol(PVK) by spin coating. We inverstigated effect of the surfactant solution and cathod electrolysis to the crystal type of $\varepsilon$-CuPc in CGL with TEM, SEM and X- ray diffraction spectroscopy and studied the mechanism of an aqueous coating for the preparation of CGL. The effect of the washing of CGL about the electrophotographic characteristics of the $\varepsilon$-CuPc/PVK doublelayered photoconductors is studied also.

• Bulletin of the Korean Chemical Society
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• v.17 no.8
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• pp.686-688
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• 1996

We have produced nanophase iron clusters inside a gas cell by decomposing iron pentacarbonyls from the mixture of ~20 Torr Fe(CO)5/~3 Torr SF6 with a pulsed CO2 laser. The product displayed a black tint. Its composition was identified to be mostly iron from an inductively coupled plasma (ICP) atomic emission spectrum. The X-ray diffraction (XRD) pattern indicates a body-centered cubic structure for the cluster. A transmission electron micrograph proves that their diameter ranges between 50 and 70 Å and their average diameter is 60 Å.

• Journal of The Korean Astronomical Society
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• v.21 no.1
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• pp.79-95
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• 1988

To examine relations between stellar activity and rotation we estimated parameters of stellar activity such as $R'_{HK}$, $R'_{MgII}$, $R'_{CII}$, $R'_{CIV}$ and $R'_{X-ray}$ from the published data which measure the activity levels of stellar chromospheres, transition regions and coronae. In the present study we considered only the main sequence stars in an attempt to minimize the influence of other stellar parameters such as radius, age and stellar convection on stellar activity since they are also known to affect the magnetic field generation. In the present analysis we selected only those stars that satisfy the following conditions: (1) flux measurements are available together with Ca II fluxes and (2) rotation periods are determined by Ca II observations. We derived relations between the ${\bar{R}}ossby$ number $R_o$ and stellar activity $R'_{HK}$, $R'_{MgII}$, $R'_{CII}$, $R'_{CIV}$ and $R'_{X-ray}$ and assessed the relations by plotting $R'_{HK}$, $R'_{MgII}$ and $R'_{X-ray}$ against rotation period $P_{rot}$ for comparison with observations. From the comparison it is found that as far as the rotation-activity relation is concerned, (1) normalized surface flux $R'_{HK}$ is better than the surface flux $F'_{HK}$, in the sense that $R'_{HK}$ differentiates the color dependence better and (2) $R'_{HK}$ defined by Rutten (1984) describes the observations notably better than $R'_{HK}$ of Noyes et al. (1984).

• Smart Structures and Systems
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• v.8 no.1
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• pp.17-37
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• 2011

The microcantilever (MCL) sensor is one of the most promising platforms for next-generation label-free biosensing applications. It outperforms conventional label-free detection methods in terms of portability and parallelization. In this paper, an overview of recent advances in our understanding of the coupling between biomolecular interactions and MCL responses is given. A dual compact optical MCL sensing platform was built to enable biosensing experiments both in gas-phase environments and in solutions. The thermal bimorph effect was found to be an effective nanomanipulator for the MCL platform calibration. The study of the alkanethiol self-assembly monolayer (SAM) chain length effect revealed that 1-octanethiol ($C_8H_{17}SH$) induced a larger deflection than that from 1-dodecanethiol ($C_{12}H_{25}SH$) in solutions. Using the clinically relevant biomarker C-reactive protein (CRP), we revealed that the analytical sensitivity of the MCL reached a diagnostic level of $1{\sim}500{\mu}g/ml$ within a 7% coefficient of variation. Using grazing incident x-ray diffractometer (GIXRD) analysis, we found that the gold surface was dominated by the (111) crystalline plane. Moreover, using X-ray photoelectron spectroscopy (XPS) analysis, we confirmed that the Au-S covalent bonds occurred in SAM adsorption whereas CRP molecular bindings occurred in protein analysis. First principles density functional theory (DFT) simulations were also used to examine biomolecular adsorption mechanisms. Multiscale modeling was then developed to connect the interactions at the molecular level with the MCL mechanical response. The alkanethiol SAM chain length effect in air was successfully predicted using the multiscale scheme.