• Title/Summary/Keyword: 분리요소모델

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Elastoplastic Behavior and Creep Analysis of Solder in a FC-PBGA Package (플립 칩 패키지 솔더의 탄소성 거동과 크립 해석)

  • Choi, Nam-Jin;Lee, Bong-Hee;Joo, Jin-Won
    • Journal of the Microelectronics and Packaging Society
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    • v.17 no.2
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    • pp.21-28
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    • 2010
  • Creep behaviors of the solder balls in a flip chip package assembly during thermal cycling test is investigated.. A material models used in the finite element analysis are viscoplastic model introduced by Anand and creep model called partitioned model. Experiment of two temperature cycles using moir$\acute{e}$ interferometry is conducted to verify the reliability of material models for the analysis of thermo-mechanical behavior. Bending deformations of the assemblies and average strains of the solder balls due to temperature change and dwell time are investigated. The results show that time-dependent shear strain of solder by the partitioned model is in excellent agreement with those by moir$\acute{e}$ interferometry, while there is considerable difference between results by Anand model and experiment. In this paper, the partitioned model is employed for the time-dependent creep analysis of the FC-PBGA package. It is also shown that the thermo-mechanical stress becomes relaxed by creep behavior at high temperature during temperature cycles.

ISDN에서의 통신망 구조 모델

  • Choe, Yang-Hui
    • ETRI Journal
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    • v.9 no.4
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    • pp.15-25
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    • 1987
  • 일반적으로 ISDN의 망구조는 4가지의 주요원칙에 의거 형성되며 발전된다고 볼 수 있다. .데이터 정보와 콘트롤 정보간의 분리 .Basic 및 advanced 서비스의 효율적인 적용 .가입자와 망간의 상호독립성 유지 .망의 계층적 구조 그러고 ISDN은 정보통화로 네트워크, 콘트롤 네트워크 및 서비스 네트워크로 구성되며 이들의 효율적인 운용으로 ISDN의 망 및 서비스기능이 설정 된다. 따라서 본 고는 이상의 사항을 구체적으로 분석하고, 그 구조모델을 검토하기 위하여 ISDN의 주요 요구사항, 기능요소, 교환구조, 기능요소들간의 통신에 관해 살펴보았다.

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단섬유강화 금속복합재료의 계면분리 및 균열

  • Kim, Jin;Koh, Byeong-Cheon
    • Journal of the KSME
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    • v.31 no.3
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    • pp.293-299
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    • 1991
  • 단섬유보강 금속복합재료의 2차가공은 금속복합재료의 넓은 범위 응용을 위해 필히 요구된다. 여러 가공방법 중 하나인 열간압출시 보강섬유파괴 및 계면에서의 접합분리 및 균열발생이 없는 제조공정의 최적화를 위해서 가공시 내부조직의 소성변형 기구 규명보다 압출력에 의한 응력분 포와 기지재료와 보강섬유 사이 계면 변화 및 기계적 특성 관계규명이 정량적으로 요구된다. 본 글에서는 유한요소법을 이용하여 계면에서의 접합상태를 임의로 가정하여 압출조건에 따른 압 출후의 보강섬유 방향 및 계면균열 및 접합분리를 거시적으로 예측하고, advanced shear-lag을 이용하여 균열 전, 후의 응력. 변형관계를 미시적으로 규명할 수 있음을 제시하였다. 그러나 향후 현상적 모델인 shear-lag 모델을 수학적 모델인 균질화법에 도입하면 미시적. 거시적 거 동해석이 함께 요구되는 금속복합재료의 열간압출거동 해석을 일체적으로 행할 수 있어 효율적 이고 정확한 예측이 가능하리라고 사료된다.

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A Simulation of Advanced Multi-dimensional Isotachophoretic Protein Separation for Optimal Lab-on-a-chip Design (최적화된 Lab-on-a-chip 설계를 위한 향상된 다차원 프로틴 등속영동 시뮬레이션)

  • Cho, Mi-Gyung
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.13 no.7
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    • pp.1475-1482
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    • 2009
  • In this paper, a computer simulation is developed for isotachophoretic protein separation in a serpentine micro channel for optimal lab on a chip design using 2D Finite Element Method. This 2D ITP model is composed of 5 components such as hydrochloric acid as Leader, caproic acid as terminator, acetic acid and benzoic acid as two proteins, and histindine as background electrolyte. The computer model is based on mass conservation equation for 5 components, charge conservation equation for electric potential, and electro neutrality condition for pH calculation. For the validation of the 2D spatial ITP model, the results are compared with the Simul5 developed by Bohuslav Gas Group. The simulation results are in a good agreement in a ID planar channel. This proves the precision of our model. The 2Dproteinseparation is conducted in a 2D curved channel for Lab on a chip design and dispersions of proteins are revealed during the electrophoretic process in a curved shape.

Application Method of Dragonfly Effect Model to SNS-based Classes (SNS 활용 교육을 위한 Dragonfly Effect 모델 적용 방안)

  • Kim, Ji-Yun;Lee, Tae-Wuk
    • Proceedings of the Korean Society of Computer Information Conference
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    • 2018.01a
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    • pp.219-222
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    • 2018
  • 최근 SNS의 부정적 활용에 관한 사례들이 증가하면서, 청소년들의 모방 가능성에 대한 우려도 함께 커졌다. 본 논문에서는 청소년들의 긍정적 SNS 활용 경험 제고를 위한 방안으로 SNS 활용 교육에 Dragonfly Effect 모델의 적용을 제안하였다. Dragonfly Effect 모델은 작은 생각을 SNS를 통해 큰 변화로 바꾸는 방법에 관한 모델이며, 본 논문에서는 이를 교육에 적용하기 위한 방안으로 요소 분리형 교육 프로그램과 요소 통합형 교육 프로그램 구성을 예시 프로그램과 함께 제안하였다. Dragonfly Effect 모델을 적용한 수업은 청소년들이 SNS를 통한 선한 사례의 주인공이 되도록 할 것이며, 또한 이것은 SNS 상에 선순환 구조가 만들어지는 작은 단초가 될 것이다.

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Investigation of Timbre-related Music Feature Learning using Separated Vocal Signals (분리된 보컬을 활용한 음색기반 음악 특성 탐색 연구)

  • Lee, Seungjin
    • Journal of Broadcast Engineering
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    • v.24 no.6
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    • pp.1024-1034
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    • 2019
  • Preference for music is determined by a variety of factors, and identifying characteristics that reflect specific factors is important for music recommendations. In this paper, we propose a method to extract the singing voice related music features reflecting various musical characteristics by using a model learned for singer identification. The model can be trained using a music source containing a background accompaniment, but it may provide degraded singer identification performance. In order to mitigate this problem, this study performs a preliminary work to separate the background accompaniment, and creates a data set composed of separated vocals by using the proven model structure that appeared in SiSEC, Signal Separation and Evaluation Campaign. Finally, we use the separated vocals to discover the singing voice related music features that reflect the singer's voice. We compare the effects of source separation against existing methods that use music source without source separation.

Investigation on the Accuracy of bundle Adjustments and Exterior Orientation Parameter Estimation of Linear Pushbroom Sensor Models (선형 푸시브룸 센서모델의 번들조정 정확도 및 외부표정요소추정 정확도 분석)

  • Kim Tae Jung
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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    • v.23 no.2
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    • pp.137-145
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    • 2005
  • In this paper, we investigate the accuracy of various sensor models developed for linear pushbroom satellite images. We define the accuracy of a sensor model in two aspects: the accuracy of bundle adjustments and the accuracy of estimating exterior orientation parameters. The first accuracy has been analyzed and reported frequently whereas the second accuracy has somewhat been neglected. We argue that the second accuracy is as important as the first one. The second accuracy describes a model's ability to predict satellite orbit and attitude, which has many direct and indirect applications. Analysis was carried out on the traditional collinearity-based sensor models and orbit-based sensor models. Collinearity-based models were originally developed for aerial photos and modified for linear pushbroom-type satellite images. Orbit-based models have been used within satellite communities for satellite control and orbit determination. Models were tested with two Kompsat-1 EOC scenes and GPS-driven control points. Test results showed that orbit-based models produced better estimation of exterior orientation parameters while maintained comparable accuracy on bundle adjustments.

Numerical Investigation of the Progressive Failure Behavior of the Composite Dovetail Specimens under a Tensile Load (인장하중을 받는 복합재료 도브테일 요소의 점진적인 파손해석)

  • Park, Shin-Mu;Noh, Hong-Kyun;Lim, Jae Hyuk;Choi, Yun-Hyuk
    • Composites Research
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    • v.34 no.6
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    • pp.337-344
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    • 2021
  • In this study, the progressive failure behavior of the composite fan blade dovetail element under tensile loading is numerically investigated through finite element(FE) simulation. The accuracy of prediction by FE simulation is verified through tensile testing. The dovetail element is one of the joints for coupling the fan blade with the disk in a turbofan engine. The dovetail element is usually made of a metal material such as titanium, but the application of composite material is being studied for weight reduction reasons. However, manufacturing defects such as drop-off ply and resin pocket inevitably occur in realizing complex shapes of the fan blade made by composite materials. To investigate the effect of these manufacturing defects on the composite fan blade dovetail element, we performed numerical simulation with FE model to compare the prediction of the FE model and the tensile test results. At this time, the cohesive zone model is used to simulate the delamination behavior. Finally, we found that FE simulation results agree with test results when considering thermal residual stress and through-thickness compression enhancement effect.

S.D.O.F Macro-element for Interaction of Deep Foundation (단자유도 매크로요소를 이용한 깊은기초의 상호작용 모델)

  • Rha, Chang-Soon
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.21 no.4
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    • pp.347-355
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    • 2008
  • In this paper single degree of freedom macro-element model was presented to investigate the interaction between soil and the deep foundation under the lateral loads. It was made by modelling each component related to the soil-structure interaction and combining them into one piece. It enhanced the conventional method that was not able to break down the interaction components in piece due to the usage of simple spring element for interaction. A proposed macro-element classified the stress components in relation to the interaction into frictional and compressive resistance. Each component was modelled using the classical plasticity theory, and finally combined in parallel. An example study was carried out using the proposed macro-element for deep foundation embedded in three layered cohesive soil. It showed improved results compared to the conventional method by producing additional information of the interaction components as well as the overall behavior of foundation.

Dynamic Characteristics Recovery of Delaminated Composite Structure (층간 분리가 있는 복합재 구조물의 동적특성 회복)

  • Sohn, Jung Woo;Kim, Heung Soo
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.28 no.1
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    • pp.47-51
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    • 2015
  • In this paper, feasibility of dynamic characteristics recovery of delaminated composite structure is numerically studied by using active control algorithm and piezoelectric actuator. Macro-fiber composite(MFC), which has great flexibility and high actuating force, is considered as an actuator in this work. After construction of finite element model for delaminated composite structure based on improved layerwise theory, modal characteristics are investigated and changes of natural frequencies and mode shapes, caused by delamination, are observed. Then, active control algorithm is realized and implemented to system model and control performances are numerically evaluated. Dynamic characteristics of delaminated composite structure are effectively recovered to those of healthy composite structure.