• 제목/요약/키워드: Formation mechanism

검색결과 2,626건 처리시간 0.031초

BONDING PHENOMENON IN TRANSIENT LIQUID PHASE BONDING OF NI BASE SUPERALLOY GTD-111

  • Kang, Chung-Yun;Kim, Dae-Up;Woo, In-Soo
    • 대한용접접합학회:학술대회논문집
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    • 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
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    • pp.798-802
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    • 2002
  • Metallurgical studies on the bonded interlayer of directionally solidified Ni-base superalloy GTD111 joints were carried out during transient liquid phase bonding. The formation mechanism of solid during solidification process was also investigated. Microstructures at the bonded interlayer of joints were characterized with bonding temperature. In the bonding process held at 1403K, liquid insert metal was eliminated by well known mechanism of isothermal solidification process and formation of the solid from the liquid at the bonded interlayer were achieved by epitaxial growth. In addition, grain boundary formed at bonded interlayer is consistent with those of base metal. However, in the bonding process held at 1453K, extensive formation of the liquid phase was found to have taken place along dendrite boundaries and grain boundaries adjacent to bonded interlayer. Liquid phases were also observed at grain boundaries far from the bonding interface. This phenomenon results in liquation of grain boundaries. With prolonged holding, liquid phases decreased gradually and changed to isolated granules, but did not disappeared after holding for 7.2ks at 1473K. This isothermal solidification occurs by diffusion of Ti to be result in liquation. In addition, grain boundaries formed at bonded interlayer were corresponded with those of base metal. In the GTD-ll1 alloy, bonding mechanism differs with bonding temperature.

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CH4/Air 예혼합화염의 하류영역에서 체류시간 및 열손실에 의한 NOx의 생성특성 (The Effect of Residence Time and Heat Loss on NOx Formation Characteristics in the Downstream Region of CH4/Air Premixed Flame)

  • 황철홍;현승호;탁영조;이창언
    • 대한기계학회논문집B
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    • 제31권1호
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    • pp.99-108
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    • 2007
  • In this study, the NOx formation characteristics of one-dimensional $CH_4$/Air premixed flame using detailed-kinetic chemistry are examined numerically. The combustor length and the amount of heat loss are varied to investigate the effect of residence time and heat loss on the NOx formation in a post-flame region. In the flame region, NO is mainly produced by the Prompt NO mechanism including $N_2$O-intermediate NO mechanism over all equivalence ratios. However, thermal NO mechanism is more important than Prompt NO mechanism in the post-flame region. In the case of adiabatic condition, the increase of combustor length causes the remarkable increase of NO emission at the exit due to the increase of residence time. On the other hand, NO reaches the equilibrium state in the vicinity of flame region, considering radiation and conduction heat losses. Furthermore the NO, in the case of $\phi$=1.2, is gradually reduced in the downstream region as the heat loss is increased. From these results, it can be concluded that the controls of residence time and heat loss in a combustor should be recognized as an important NOx reduction technology.

인센티브 매커니즘에 기반한 효율적인 이동 크라우드소싱 기법에 대한 연구 (A New Effective Mobile Crowdsourcing Control Scheme Based on Incentive Mechanism)

  • 박광현;김승욱
    • 정보처리학회논문지:컴퓨터 및 통신 시스템
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    • 제8권1호
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    • pp.1-8
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    • 2019
  • 본 논문에서는 모바일 크라우드소싱 환경에서 게임이론의 인센티브 매커니즘 기법과 중복 연합 형성 게임(Overlapping Coalition Formation Game)을 적용하여 시스템의 진실성을 보장하고 모바일 노드의 이득을 극대화하는 효율적인 기법을 제안한다. 제안된 매커니즘 기법은 노드가 자신의 정보를 솔직하게 드러냈을 때 가장 높은 보상을 지급함으로써 노드가 진실된 정보를 보고하도록 한다. 또한 중복 연합 형성 게임을 적용함으로써 노드들은 자신 주변의 가장 높은 보상을 지급하는 연합을 선택하고 자신의 자원이 허락하는 한 다수의 연합에 참가하여 업무를 수행함으로써 효율성을 높일 수 있었다. 컴퓨터 시뮬레이션을 통해 기존에 제안된 다른 기법에 비해 제안된 기법은 모바일 노드들이 높은 보상을 얻기 위해 자신의 정보를 솔직하게 드러냈고 자신의 성능과 남은 자원에 따라 더 높은 보상을 받을 수 있음을 확인할 수 있었다.

밀링가공시 버 형성 예측을 위한 전문가 시스템 개발 (II) - 복잡한 형상의 피삭재와 다중경로에 의한 밀링가공시 (Development of Expert System for Burr Formation Prediction in Face Milling (II) - In Milling Multi Featured workpiece with Multi)

  • 고성림;김영진;장재은;이장범;김지환
    • 한국정밀공학회지
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    • 제20권12호
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    • pp.25-33
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    • 2003
  • A burr has been defined as undesirable projection of material formed as a result of plastic flow from a cutting or shearing operation. It is unavoidable in all kinds of machining operation. As a result, burr makes troubles on manufacturing process due to deburring cost, quality of products and productivity. In this study, the primary interest is about exit burr. The burr formation mechanism in each type of burr is classified. Data bases are developed to predict burr formation result. In the milling operation, we develop an algorithm to analyze the burr formation mechanism by the geometrical analysis on the multi featured workpiece with multi cutting path. The algorithm includes three steps, i. e., the feature identification, the cutting condition identification, and the analysis on exit burr formation. We can predict which portion of workpiece would have the exit burr in advance so that we can manage to find a way to minimize the exit burr formation in an actual cutting. Also, this algorithm can be implemented in a commercial CAM package so that we can simulate the NC code to review the burr formation in advance.

The Personal Data Protection Mechanism in the European Union

  • Syroid, Tetiana L.;Kaganovska, Tetiana Y.;Shamraieva, Valentyna M.;Perederiі, Оlexander S.;Titov, Ievgen B.;Varunts, Larysa D.
    • International Journal of Computer Science & Network Security
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    • 제21권5호
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    • pp.113-120
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    • 2021
  • The adoption of the General Data Protection Regulation (EU) 2016/679 transformed approaches and concepts to the implementation of the personal data protection mechanism in the European Union. Within the EU, almost all countries have adapted a new protection mechanism, which requires a study of the specifics of its use. The article intends to assess the legal provisions of the current mechanism of personal data protection in the EU. The author studied the mechanism of personal data protection under the General Data Protection Regulation (EU) 2016/679 (GDPR) based on the concept of contextual integrity and analysis of EU legislation on personal data protection. The scientific publications for 2016-2020 were reviewed for the formation of ideas of a new personal data protection mechanism in the EU, informative and transparent analysis of legal provisions. The article notes that the personal data privacy and protection is increasing, there is an ongoing unification of the legal status of personal data protection and the formation of a digital market for dissemination, exchange, control, and supervision of data. Cross-border cooperation is part of the personal data protection mechanism. The author proved that the GDPR has changed approach to personal data protection: the emphasis is now shifting to the formation of a digital market, where the EU's role in ensuring regulation is crucial. The article identifies the emergence of a new protectionist legal system and strengthening of legal provisions regarding privacy. This legal system needs unification and harmonization in accordance with national legislation, is territorially fragmented and differentiated within the EU.

칩브레이커 사용에 따른 밀링버의 생성특성 연구 (Burr Formation Characteristics due to Chip Breaker in Milling Process)

  • 황덕철;황준;우창기
    • 한국공작기계학회:학술대회논문집
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    • 한국공작기계학회 2001년도 춘계학술대회 논문집(한국공작기계학회)
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    • pp.78-82
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    • 2001
  • This paper presents the numerical analysis and experimental verification to know the metal cutting burr formation mechanism in face milling operation. Finite element method are applied to predict the 2-D burr formation process prediction. Face milling process are adjusted to analyze the characteristics of burr shapes according to various cutting conditions. The cutting parameters were investigated with cutting speed, feed rate, depth of cut. Through a few experiments, various burr types are classified according to its shape and properties.

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유한요소법을 이용한 절삭가공 Burr 예측과 생성특성 연구 (Burr Prediction via Finite Element Method and Burr Formation Characteristics in Metal Cutting Process)

  • 황준;황덕철;우창기;양계준
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 2001년도 춘계학술대회 논문집
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    • pp.1000-1003
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    • 2001
  • This paper presents the numerical analysis and experimental verification to know the metal cutting burr formation mechanism in face milling operation. Finite element method are applied to predict the 2-D burr formation process prediction. Face milling process are adjusted to analyze the characteristics of burr shapes according to various cutting conditions. The cutting parameters were investigated with cutting speed, feed rate, depth of cut. Through the experiments various burr types are classified according to its shape and properties.

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대향류 비예혼합화염과 상호작용하는 단일 와동의 생성특성에 관한 연구 (An Investigation on the Formation Characteristics of a Single Vortex Interacting with Counterflow Nonpremixed Flame)

  • 유병훈;오창보;황철홍;이창언
    • 한국연소학회:학술대회논문집
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    • 한국연소학회 2002년도 제25회 KOSCI SYMPOSIUM 논문집
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    • pp.49-56
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    • 2002
  • A two-dimensional direct numerical simulation is performed to investigate the formation characteristics of a single vortex interacting with $CH_4/N_2$-Air counterflow nonpremixed flame. The numerical method was based on a predictor-corrector scheme for a low Mach number flow. The detailed transport properties and a 16-step augmented reduced mechanism are adopted in this calculation. The budgets of the vorticity transport equation arc examined to reveal the mechanisms leading to the formation, evolution and dissipation of a single vortex interacting with counterflow nonpremixed flame. It is found that the stretching term, which depends on the azimuthal component of vorticity, and radial velocity, mainly generates vortieitv in non-reacting and reacting flows. The viscous and baroclinic torque term destroy the vorticity in non-reacting flow. In addition, the baroclinic torque term due to density and pressure gradient generates vorticity, while viscous and the volumetric expansion terms due to density gradient destroy vorticity in reacting flow.

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Ti 합금의 고속가공시 밀링특성에 관한 연구 (High speed milling titanium alloy)

  • Ming CHEN;Youngmoon LEE;Seunghan YANG;Seungil CHANG
    • 한국공작기계학회:학술대회논문집
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    • 한국공작기계학회 2003년도 춘계학술대회 논문집
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    • pp.454-459
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    • 2003
  • The paper will present chip formation mechanism and surface integrity generation mechanism based on the systematical experimental tests. Some basic factors such as the end milling cutter tooth number, cutting forces, cutting temperature, cutting vibration, the chip status, the surface roughness, the hardness distribution and the metallographic texture of the machined surface layer are involved. the chip formation mechanism is typical thermal plastic shear localization at high cutting speed with less number og shear ribbons and bigger shear angle than at low speed, which means lack of chip deformation. The high cutting speed with much more cutting teeth will be beneficial to the reduction of cutting forces, enlarge machining stability region, depression of temperature increment, auti-fatigability as well as surface roughness. The burrs always exists both at low cutting speed and at high cutting speed. So the deburr process should be arranged for milling titanium alloy in any case.

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소셜 빅데이터 특성을 활용한 ICT 정책 격발 메커니즘 분석방법 제안 (A Study on the Analysis Method of ICT Policy Triggering Mechanism Using Social Big Data)

  • 최홍규
    • 한국멀티미디어학회논문지
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    • 제24권8호
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    • pp.1192-1201
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    • 2021
  • This study focused on how to analyze the ICT policy formation process using social big data. Specifically, in this study, a method for quantifying variables that influenced policy formation using the concept of a policy triggering mechanism and elements necessary to present the analysis results were proposed. For the analysis of the ICT policy triggering mechanism, variables such as 'Scope', 'Duration', 'Interactivity', 'Diversity', 'Attention', 'Preference', 'Transmutability' were proposed. In addition, 'interpretation of results according to data level', 'presentation of differences between collection and analysis time points', and 'setting of garbage level' were suggested as elements necessary to present the analysis results.