• 소성∙가공
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• 제19권1호
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• pp.44-49
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• 2010

It has been widely reported that carbide-free bainitic steels or super-bainite TRIP (SB-TRIP) steels for the automotive industry are a new family of steels offering a unique combination of high strength and ductility. Hence, it is important to exactly evaluate the volume fraction of RA and to identify the 3-D morphology of constituent phases, because it plays a crucial role in mechanical properties. Recently, as electron back-scattered diffraction (EBSD) equipped with focused ion beam (FIB) has been developed, 3-D EBSD technique for materials science are used to these steels. Moreover, newly developed atom probe tomography (APT) technique can provide the exact distribution and chemical concentration of alloying elements in a sub-nm scale. The APT analysis results indicate exactly the distribution and composition of alloying elements in the austenite and bainite phases of SB-TRIP steels with the atomic-scale resolution. And thus, no partitioning of aluminum and manganese atoms was showed between the austenite containing $7.73{\pm}0.39$ at% C and the bainitic ferrite associated with $0.22{\pm}0.06$ at% C in SB-TRIP steel.

• Nuclear Engineering and Technology
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• 제44권5호
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• pp.491-500
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• 2012

The dissimilar metal joints welded between Ni-based alloy, Alloy 690 and low alloy steel, A533 Gr. B with Alloy 152 filler metal were characterized by using optical microscope, scanning electron microscope, transmission electron microscope, secondary ion mass spectrometry and 3-dimensional atom probe tomography. It was found that in the weld root region, the weld was divided into several regions including unmixed zone in Ni-base alloy, fusion boundary, and heat-affected zone in the low alloy steel. The result of nanostructural and nanochemical analyses in this study showed the non-homogeneous distribution of elements with higher Fe but lower Mn, Ni and Cr in A533 Gr. B compared with Alloy 152, and the precipitation of carbides near the fusion boundary.

• Macromolecular Research
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• 제16권2호
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• pp.169-177
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• 2008

This paper reports a facile synthesis of new water-soluble poly(ethylene oxide) (PEO)-based amphiphilic block copolymers showing pH sensitive phase transition behaviors. The copolymers were prepared by atom transfer radical polymerization (ATRP) of methacrylamide type of monomers carrying a sulfonamide group using a PEO-based macroinitiator and a Cu(I)Br/$Me_6TREN$ catalytic system in aqueous media. The resulting polymers were characterized by a combination of $^1H$-NMR, size exclusion chromatography, and UV/Visible spectrophotometeric analysis. The micellization of the block copolymers as a drug-loading mechanism in aqueous media using fluorescein salt was examined as a function of pH. The stable micelle formation and its loading efficacy suggest that the block copolymers can be used as precursors for drug-nanocontainers.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.61-62
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• 2002

In order to clarify the contact mechanism between specimen surface and probe tip in the surface observation by the AFM (atomic force microscope) or the FFM (friction force microscope), several molecular dynamics simulations have been performed. In the simulation, a 3-dimensional simulation model is proposed where the specimen and the probe are assumed to consist of mono-crystal line copper and a carbon atom respectively and the effect of cantilever stiffness is also taken into considered. The surface observation process on a well-defined Cu{100} is simulated. The influences of cantilever stiffness on the reactive force images and the behavior of probe tip were evaluated. As a resuIt, several phenomena similar to those observed by the actual surface observation experiment, such as double-slip behavior and dispersion in the stick-slip wave period were observed.

• 반도체디스플레이기술학회지
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• 제7권1호
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• pp.7-10
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• 2008

Effect of Pd addition on crystal structures of two nickel silicides, NiSi and $NiSi_2$, is investigated by using an ab initio calculation. A Pd atom substitutes a Ni and Si site, respectively, to evaluate the preferable site between them. Pd prefers Ni site to Si site in NiSi, while it prefers Si site to Ni site in $NiSi_2$. The calculated total energy also indicates that the Pd substitution to Si site stabilizes the $NiSi_2$ structure. This calculated data matches well with the experimental data obtained from Atom probe.

• 한국재료학회지
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• 제10권9호
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• pp.601-606
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• 2000

Ni mono-silicide는 선폭이 0.15$\mu\textrm{m}$이하에서도 전기저항이 커지는 현상이 없고 Ni와 Si이 1:1로 반응하기 때문에 얇은 실리사이드의 제조가 가능하고 도펀트의 재분포 현상을 감소시킬수 있다. 따라서 0.15$\mu\textrm{m}$급 이하 디바이스에 사용이 기대되는 NiSi의 제조를 위한 Ni 박막의 증착조건 확보와 열처리 조건에 따른 NiSi의 기초 물성조사를 수행하였다. Ni mono-silicide는 sputter의 물리적 증착방법으로 Ni 박박을 증착후 관상로를 상용하여 $150~1000^{\circ}C$ 온도 범위에서 제조하였다. 그후 SPM을 이용하여 각 시편의 표면조도를 측정하였고, 미세구조와 성분분석은 EDS가 장착된 TEM을 사용하여 측정하였다. 각 열처리 온도별 생성상의 전기적 성질은 4 point probe로 측정하였다. 본 연구의 결과, SPM은 비파괴 방법으로 NiSi가 NiSi$_2$로 변태되었는지 확인할 수 있는 효과적인 공정모니터링 방법임을 확인하였고, $800^{\circ}C$이상 공온 열처리에 잔류 Ni의 산화방지를 의해 산소분압의 제어가 $Po_2$=1.5$\pm$10(sup)-11색 이하가 되어야 함을 알 수 있었으며, 전지적 특성실험으로부터 본 연구에서 제조된 박막의 NiSi$\longrightarrow$NiSi$_2$ 상태변온도는 $700^{\circ}C$라고 판단되었다.

• 대한기계학회논문집B
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• 제36권1호
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• pp.25-29
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• 2012

탄소나노튜브의 기계적 특성과 금속의 전기적 특성을 이용할 수 있는 나노 복합구조체의 특성은 두 재료 사이의 계면이 중용한 역할을 한다. 본 연구에서는 나노임프린트 패터닝을 이용하여 촉매금속을 패턴하고 이를 이용한 개별 성장된 탄소나노튜브 위에 증기증착법을 이용하여 니켈을 증착한 나노구 조체의 계면을 조사하였다. 이를 위하여 고해상의 투사전자현미경과 3 차원 원자 프로브 분석기를 이용하였다. 탄소나노튜브 위에서 성장된 나노결정의 경우 준 안정 상태인 조밀입방구조의 $Ni_3C$ 를 형성하는 것으로 나타났다. 이러한 특성을 이용한 나노복합체의 응용가능성을 살펴보았다.

• 반도체디스플레이기술학회지
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• 제2권3호
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• pp.19-23
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• 2003

Extended unbalanced magnetron sputtering system based on the cylindrical magnetron with a rotating cathode was developed. The unbalanced configuration of magnetic field was realized by means of additional lines of permanent magnets, placed along both sides of a 89 mm outer diameter and 600 mm long cylindrical cathode. The performance of the unbalanced magnetron was assessed in terms of the ion current density and the ion-to-atom ratio incident at the substrate. Furthermore, the paper presents the comparison of the internal plasma parameters, such as the electron temperature, electron density, plasma and floating potentials, measured by a Langmuir probe in various positions from the cathode, for conventional and unbalanced constructions of the cylindrical magnetron. The plasma density and ion current density are about 3-5 times higher than those of conventional one, in the unbalanced magnetron in a 0.24 Pa Ar atmosphere with a DC cathode power of 3 kW.

• Bulletin of the Korean Chemical Society
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• 제29권1호
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• pp.177-180
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• 2008

Laser induced fluorescence studies of hydrogen atom using four wave mixing technique are reported for the photodissociation of CH4 and its isotopomers at Lya (121.6 nm). The source of dissociating and probe radiation is one and the same (delay time??20 nsec). The average translational energy of ejected hydrogen atoms (50 Kcal/mol) reveals that CH4 + hn??CH3 + H(2S) and CH4 + hn??CH2(a1A1) + H2(1Sg) are the main dissociation processes. The absolute quantum yield for CH4 and CD4 are the same, FH(CH4) = FD(CD4) = 0.31 0.05. If one divides the experimental H/D ratios from the isotopomers CH3D, CH2D2, CHD3 by the isotopic H/D ratios, a value 2 is obtained in all three cases. Overall, the heavier D atoms are more likely than the H atoms to remain attached to the carbon atom.

• IEIE Transactions on Smart Processing and Computing
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• 제6권4호
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• pp.262-268
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• 2017

Intelligent video surveillance systems have been developed to monitor global areas and find specific target objects using a large-scale database. However, person re-identification presents some challenges, such as pose change and occlusions. To solve the problems, this paper presents an improved person re-identification method using sparse representation and saliency-based dictionary construction. The proposed method consists of three parts: i) feature description based on salient colors and textures for dictionary elements, ii) orthogonal atom selection using cosine similarity to deal with pose and viewpoint change, and iii) measurement of reconstruction error to rank the gallery corresponding a probe object. The proposed method provides good performance, since robust descriptors used as a dictionary atom are generated by weighting some salient features, and dictionary atoms are selected by reducing excessive redundancy causing low accuracy. Therefore, the proposed method can be applied in a large scale-database surveillance system to search for a specific object.