• Journal of Ceramic Processing Research
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• 제13권spc2호
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• pp.359-362
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• 2012

We have employed Kelvin force microscopy (KFM) system to measure the potential change of a single SnO2 nanowire which had been synthesized on the Au thin film by a thermal process. By using the KFM probing technique, Rh coated conducting cantilever can approach a single SnO2 nanowire in nano scale and get the potential images with oscillating AC bias between Au electrode and cantilever. Also, during imaging the potential status, we controlled the concentration of oxygen in measuring chamber to change the ionosorption rate. From the results of such experiments, we verified that the surface potential as well as doping type of a single SnO2 nanowire could be changed by oxygen ionosorption.

• 마이크로전자및패키징학회지
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• 제27권4호
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• pp.61-65
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• 2020

열전소재의 격자열전도도 저감은 열전성능 증대를 위해 가장 빈번하게 사용되는 방법이다. 하지만 전체 열전도도에서 다른 열전도도 기여분을 제외하는 방법으로만 격자열전도도를 구할 수 있기 때문에 격자열전도도를 정확하게 분석하는 것을 간단한 작업이 아니다. 본 연구에서는 먼저 전자/홀에 의한 열전도도 기여분 (모든 소재 적용)과 쌍극 전도에 의한 기여분 (작은 밴드 갭 소재 적용)을 정확하게 계산해야만 격자열전도도를 정확하게 분석할 수 있음을 설명한다. 전자/홀에 의한 기여분을 계산하기 위해 필수적인 로렌츠 숫자 계산법 (싱글 파라볼릭 모델링 및 간단한 식 이용)과 쌍극 전도에 의한 기여분 계산법 (투 밴드 모델링) 또한 소개한다. 격자열전도도의 정확한 분석은 격자열전도도 저감을 위한 여러 결함 제어 전략의 효과를 객관적으로 평가할 수 있는 강력한 분석 도구로 사용될 수 있다.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2009년도 추계학술발표대회
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• pp.39.2-39.2
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• 2009

In this work, Poly($\varepsilon$-Caprolactone)(PCL) andpoly(3-hydroxybutyrate-co-3-hydroxyvalerate)(PHBV) mats were fabricated usingelectrospinning process. The electrospinning process is a simple and efficient method to fabricate the nanofibrous mats. PCL and PHBV is a kind of biodegradable polymer but their mechanical properties aren't good. For improving mechanical properties, PHBV mats were coated by TCP. Using PCL mats and TCP-coated PHBV composite mats, a bio-resorbablebone plate were made by pressing. Detailed micro-structural characterization was done by SEM techniques. Tensile strength and bending strength were also evaluated for mechanical properties. The cytotoxicity evaluation ofPCL/TCP-coated PHBV composite multilayer was done by MTT assay. The evidence obtained in this work implies the potential for use as a biodegradable boneplate.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.166-171
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• 2007

The characterization of monolithic SiC and SiCf/SiC composite materials fabricated by NITE and RS processes was investigated in conjunction with the detailed analysis of their microstructure and density. The NITE-SiC based materials were fabricated, using a SiC powder with average size of 30 nm. RS- SiCf/SiC composites were fabricated with a complex slurry of C and SiC powder. In the RS process, the average size of starting SiC particle and the blending ratio of C/SiC powder were $0.4\;{\mu}m$ and 0.4, respectively. The reinforcing materials for /SiC composites were BN-SiC coated Hi-Nicalon SiC fiber, unidirectional or plain woven Tyranno SA SiC fiber. The characterization of all materials was examined by the means of SEM, EDS and three point bending test. The density of NITE-SiCf/SiC composite increased with increasing the pressure holding time. RS-SiCf/SiC composites represented a great decrease of flexural strength at the temperature of $1000\;^{\circ}C.$

• Fibers and Polymers
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• 제2권2호
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• pp.71-74
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• 2001

Surface characterization of materials has been considered critical in the development of biomaterials, as many unfavorable responses from the body occur at the interface between a material and the body component. The contact angle measurement is one means to characterize the surface properties and to correlate them to the biocompatibility of materials. In this paper, surface characteristics of silk fibroin/S-carboxymethyl kerateine, representative fibrous proteins, were investigated by contact angle measurements of ESCA. The biocompatibility of the blends was evaluated based on minimal interfacial free energy concept, and compared with other potential biomaterials. It was also hypothesized that the enhanced surface polarity of the blends was generated from the conformational transition of proteins. This approach to evaluate the biocompatibility of materials based on surface characteristics may find wide utility in many biomedical applications.

• 한국세라믹학회지
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• 제48권2호
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• pp.147-151
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• 2011

In this study, we prepared graphene by using the modified Hummers-Offeman method and then introduced the metals (Pt, Pd and Fe) for dispersion on the surface of the graphene for synthesis of metal-graphene composites. The characterization of the prepared graphene and metal-graphene composites was performed by X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis and transmission electron microscopy (TEM). According to the results, it can be observed that the prepared graphene consists of thin stacked flakes of shapes having a well-defined multilayered structure at the edge. And the metal particles are dispersed uniformly on the surface of the graphene with an average particle size of 20 nm.

• Applied Microscopy
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• 제42권4호
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• pp.223-227
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• 2012

Focused Ion Beam (FIB) systems have incorporated versatile nanomanipulators with inherent sophisticated machining capability to characterize the electrical properties of highly miniature components of electronic devices. Carbon fibers were chosen as a model system to test the applicability of nanomanipulators to microscale electronic materials, with special emphasis on the direct current current-voltage characterizations in terms of electrode configuration. The presence of contact resistance affects the electrical characterization. This resistance originates from either i) the so-called "spreading resistance" due to the geometrical constriction near the electrode - material interface or ii) resistive surface layers. An appropriate electrode strategy is proposed herein for the use of FIB-based manipulators.

• Applied Microscopy
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• 제45권3호
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• pp.131-134
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• 2015

Here we show how by processing energy dispersive X-ray spectrometry (EDS) data obtained using highly sensitive, new generation EDS detectors in the AZtec LayerProbe software we can obtain data of sufficiently high quality to non-destructively measure the number of layers in two-dimensional (2D) $MoS_2$ and $MoS_2/WSe_2$ and thereby enable the characterization of working devices based on 2D materials. We compare the thickness measurements with EDS to results from atomic force microscopy measurements. We also show how we can use electron backscatter diffraction (EBSD) to address fabrication challenges of 2D materials. Results from EBSD analysis of individual flakes of exfoliated $MoS_2$ obtained using the Nordlys Nano detector are shown to aid a better understanding of the exfoliation process which is still widely used to produce 2D materials for research purposes.

• Current Optics and Photonics
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• 제7권2호
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• pp.147-156
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• 2023

Circularly polarized (CP) emission can be achieved by integrating emissive materials into chiral metasurfaces. Such CP light sources in integrated device platforms are desirable for important potential applications. However, the exact characterization of the polarization state in CP emission may include some errors because of the unwanted polarization distortion caused by optical components (e.g., beam splitter) in the optical setup. Here, we consider CP emission measurements from chiral metasurfaces and characterize the polarization distortion caused by the beam splitter. We first detail the procedures for the Stokes parameters and Mueller matrix measurements. Then, we directly measure the Mueller matrix of the beam splitter and retrieve the original polarization state of CP emission from our metasurface sample. Using the measured Mueller matrix of the beam splitter, we specifically identify what contributes to polarization distortion in CP emission. Our work may provide useful guidelines for the characterization and compensation of polarization distortion in general Stokes parameter measurements.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2004년도 International Symposium on Powder Materials and Processing
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• pp.70-70
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• 2004