• 제목/요약/키워드: Materials characterization

검색결과 2,929건 처리시간 0.026초

Influence of Silicon and Seed Particles on the Reconstruction Characteristics and Exaggerated Grain Growth of MgO Protective Layer by Over-Frequency Accelerated Discharge in ACPDPs

  • Kwon, Sang-Koo;Kim, Jeong-Ho;Moon, Seung-Kyu;Choi, Jong-Kwon;Park, Kyu-Ho;Han, Sung-Su
    • 한국정보디스플레이학회:학술대회논문집
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    • 한국정보디스플레이학회 2008년도 International Meeting on Information Display
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    • pp.957-960
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    • 2008
  • The influences of silicon and MgO seed particle on the reconstruction characteristics of MgO protective layer were investigated to clarify the mechanism of reconstruction and exaggerated grain growth (EGG) in AC-PDP. The reconstruction and EGG are closely correlated with the driving force for nucleation and growth, interface energy and initial size distribution of MgO protective layer in plasma space during discharge in AC-PDP.

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Reconstruction Characteristics of MgO (111) Textured Protective Layer by Over-Frequency Accelerated Discharge in AC Plasma Display Pannel

  • Kwon, Sang-Koo;Kim, Jeong-Ho;Moon, Seung-Kyu;Kim, Hyun-Ha;Park, Kyu-Ho;Kim, Sung-Tae
    • 한국정보디스플레이학회:학술대회논문집
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    • 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권1호
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    • pp.224-227
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    • 2007
  • The reconstruction characteristics of MgO (111) textured protective layer by over-frequency accelerated discharge in AC-PDP were investigated and correlated to the variations of electronic structures. The reconstruction process and exaggerated grain growth (EGG) were explained by defect-assisted 2-D nucleation and growth mechanism combined with charged cluster model.

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Issues with the electrical characterization of graphene devices

  • Lee, Byoung-Hun;Lee, Young-Gon;Jung, Uk-Jin;Kim, Yong-Hun;Hwang, Hyeon-Jun;Kim, Jin-Ju;Kang, Chang-Goo
    • Carbon letters
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    • 제13권1호
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    • pp.23-28
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    • 2012
  • Graphene is an attractive material for device applications, but device characteristics are very unstable because the graphene is very sensitive to environmental factors such as charges nearby the graphene, metal contacts, defects, contaminants and other adsorbates. Since the interactions between graphene and environmental factors affect the electrical characteristics of graphene devices, the interpretation of electrical characteristics as simple as current-voltage curves is non-trivial, despite the common practice of using well known electrical characterization methods that have been used in silicon MOSFET. This paper addresses major obstacles in the electrical characterization of graphene devices and offers countermeasures to improve the accuracy of electrical characterization methods.

직교 직물 복합재료 물성치 예측을 위한 가상 수치 실험 (Virtual Experimental Characterization of 3D Orthogonal Woven Composite Materials)

  • 이창성;신헌;김승조
    • 한국복합재료학회:학술대회논문집
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    • 한국복합재료학회 2001년도 춘계학술발표대회 논문집
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    • pp.205-210
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    • 2001
  • In this work, virtual material characterization of 3D orthogonal woven composites is performed to predict the elastic properties by a full scale FEA. To model the complex geometry of 3D orthogonal woven composites, an accurate unit structure is first prepared. The unit structure includes warp yarns, filler yarns, stuffer yams and resin regions and reveals the geometrical characteristics. For this virtual experiments by using finite element analysis, parallel multifrontal solver is utilized and the computed elastic properties are compared to available experimental results and the other analytical results. It is founded that a good agreement between material properties obtained from virtual characterization and experimental results. Using the method of this virtual material characterization, the effects of inconsistent filler yarn distribution on the in-plane shear modulus and filler yarn waviness on the transverse Young's modulus are investigated. Especially, the stiffness knockdown of 3D woven composite structures is simulated by virtual characterization. Considering these results, the virtual material characterization of composite materials can be used for designing the 3D complex composite structures and may supplement the actual experiments.

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반용융 재료의 물성치 평가에 관한 연구(II) -모델재료의 후방압출 실험과 상계해석을 통한 반용융 재료의 유동응력식 결정- (A Study on Material Characterization of Semi-Solid Materials(II) -Determination of Flow Stress For Semi-Solid Materials Using Backward Extrusion Experiment with Model Material and Upper Bound Analysis-)

  • 이주영;김낙수
    • 소성∙가공
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    • 제8권4호
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    • pp.374-383
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    • 1999
  • To determine the flow stress of semi-solid materials, a new combined method has been studied by experimental and analytic technique in the current approach. Using backward extrusion experiment and its numerical analysis, the characterization scheme of semi-solid materials according to the change of initial solid volume fraction has been proposed. Because that solid volume fraction is sensitive to temperature change, it is required to precisely control the temperature setting. Model materials can guarantee the establishment of material characterization technique from the noise due to temperature change. Thus, clay mixed with bonded abrasives was used for experiment and the change of initial solid fraction was copied out through the variation of mixing ratio. Upper bound method was adapted to increase in efficiency of the calculation in numerical analysis and new kinematically admissible velocity field was employed to improve the accuracy of numerical solution. It is thought that the material characterization scheme proposed in this study can be applied to not only semi-solid materials, but also other materials that is difficult to obtain the simple stress state.

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Determination of the elastic properties in CFRP composites: comparison of different approaches based on tensile tests and ultrasonic characterization

  • Munoz, Victor;Perrin, Marianne;Pastor, Marie-Laetitia;Welemane, Helene;Cantarel, Arthur;Karama, Moussa
    • Advances in aircraft and spacecraft science
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    • 제2권3호
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    • pp.249-261
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    • 2015
  • The mechanical characterization of composite materials is nowadays a major interest due to their increasing use in the aeronautic industry. The design of most of these materials is based on their stiffness, which is mainly obtained by means of tensile tests with strain gauge measurement. For thin laminated composites, this classical method requires adequate samples with specific orientation and does not provide all the independent elastic constants. Regarding ultrasonic characterization, especially immersion technique, only one specimen is needed and the entire determination of the stiffness tensor is possible. This paper presents a study of different methods to determine the mechanical properties of transversely isotropic carbon fibre composite materials (gauge and correlation strain measurement during tensile tests, ultrasonic immersion technique). Results are compared to ISO standards and manufacturer data to evaluate the accuracy of these techniques.