• 제목/요약/키워드: micro modeling

검색결과 436건 처리시간 0.027초

소형화된 배전선로의 실험적 제작을 위한 기초 연구 (A Study on Basic Technology for the Experimental Making of Miniaturized Electrical Power Distribution Line)

  • 오세필;최성철;김영민;강하나;고윤석
    • 한국전자통신학회논문지
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    • 제12권6호
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    • pp.1107-1114
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    • 2017
  • 본 논문에서는 소형화된 배전선로의 실험적 제작에 대한 연구를 수행하였다. 배전계통을 분석하여 스마트 그리드 배전계통을 모델링하였으며, 소형화된 마이크로 3상 배전계통 리클로저를 설계하였다. 마이크로 리클로저는 센서부, 주제어부 그리고 릴레이부로 설계하였으며, 주제어부는 DSP를 기반으로 입력전류로부터 고장여부를 판별하여 고장전류를 차단하도록 설계하였다. 끝으로 설계 결과를 기반으로 마이크로 3상 배전계통과 마이크로 3상 리클로저를 실험적으로 제작함으로서 기초 제작 기술을 확보하였다.

검출기 측정 용적에 따른 Dosimetric Leaf Gap 변화와 정확성 검증에 대한 연구 (Assessment of Dosimetric Leaf Gap According to Measuring Active Volume of Detector)

  • 김대현
    • 한국방사선학회논문지
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    • 제16권7호
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    • pp.863-870
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    • 2022
  • DLG (Dosimetric Leaf Gap)와 투과계수는 방사선치료계획 시스템에서 MLC 모델링의 중요 매개변수이다. 본 연구에서는 측정 용적이 다른 검출기를 이용하여 HD-MLC의 DLG와 투과계수를 측정하였고, DLG의 최적화를 통해 방사선 치료계획의 정확성을 평가하였다. 용적이 작은 Semiflux3D, MicroDiamond 검출기로 Dynamic Sweeping Gap 방법을 통해 DLG를 측정하였다. 측정된 DLG 값을 최적화할 수 있도록 10개의 방사선치료계획을 생성하고 QA결과와 비교하였다. 6, 8, 10 MV에서 Semiflux3D로 측정한 DLG는 0.76, 0.83, 0.85 mm 였고, MicroDiomond로 측정한 DLG는 0.78. 0.86, 0.9 mm 였다. 방사선치료계획 시스템에서 검출기로 측정한 DLG와 최적화된 DLG 값으로 생성한 10개의 치료계획을 Postal dosimetry로 QA하여 감마분석 하였다. 6 MV 광자선의 감마분석결과 2 mm/2% 기준에서 DLG 0.78 mm는 평균 94.3%였고, DLG 1.15 mm는 평균 98.4%였다. 10 MV 광자선에서도 DLG 0.9 mm는 평균 91.2%, DLG 1.25 mm는 97.6%였다. HD-MLC의 사용은 방사선치료계획 시스템에 정확한 모델링이 완성되어야 한다. DLG 값을 검출기로 측정하여 임상에 사용할 수 있지만, DLG 값의 최적화가 이루어진다면 환자에게 더 유용한 방사선 치료를 전달할 수 있을 것이다.

Structural modeling of actuation of IPMC in dry environment: effect of water content and activity

  • Swarrup, J. Sakthi;Ranjan, Ganguli;Giridhar, Madras
    • Smart Structures and Systems
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    • 제19권5호
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    • pp.553-565
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    • 2017
  • Structural modeling of unencapsulated ionic polymer metal composite (u-IPMC) actuators that are used for flapping the insect scale-flapping wing of micro air vehicles (FMAV) in dry environmental conditions is carried out. Structural modeling for optimization of design parameters for retention of water, maximize actuation performance and to study the influence of water activity on the actuation characteristics of u-IPMC is explored for use in FMAV. The influence of equivalent weight of Nafion polymer, cations, concentration of cations, pre-treatment procedures on retention of water of u-IPMCs and on actuation parameters, flapping angle, flexural stiffness and actuation displacement are investigated. IPMC designed with Nafion having equivalent weight 900-1100, pre-heated at $30^{\circ}C$ and with sodium as the cations is promising for optimum retention of water and actuation performance. The actuation parameters while in operation in dry and humid environment with varying water activity can be tuned to desirable frequency, deflection, flap angle and flexural stiffness by changing the water activity and operational temperature of the environment.

Study on the micro-scale simulation of wind field over complex terrain by RAMS/FLUENT modeling system

  • Li, Lei;Zhang, Li-Jie;Zhang, Ning;Hu, Fei;Jiang, Yin;Xuan, Chun-Yi;Jiang, Wei-Mei
    • Wind and Structures
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    • 제13권6호
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    • pp.519-528
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    • 2010
  • A meteorological model, RAMS, and a commercial computational fluid dynamics (CFD) model, FLUENT are combined as a one-way off-line nested modeling system, namely, RAMS/FLUENT system. The system is experimentally applied in the wind simulation over a complex terrain, with which numerical simulations of wind field over Foyeding weather station located in the northwest mountainous area of Beijing metropolis are performed. The results show that the method of combining a meteorological model and a CFD model as a modeling system is reasonable. In RAMS/FLUENT system, more realistic boundary conditions are provided for FLUENT rather than idealized vertical wind profiles, and the finite volume method (FVM) of FLUENT ensures the capability of the modeling system on describing complex terrain in the simulation. Thus, RAMS/FLUENT can provide fine-scale realistic wind data over complex terrains.

공기 중 광대역 초음파 방사용 압전 박막 기반 초소형 초음파 트랜스듀서의 설계 (Design of piezoelectric micro-machined ultrasonic transducer for wideband ultasonic radiation in air)

  • 안홍민;진재혁;문원규
    • 한국음향학회지
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    • 제39권2호
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    • pp.87-97
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    • 2020
  • 본 논문에서는 공기 중 광대역 초음파 방사용 압전 박막 기반 초소형 초음파 트랜스듀서(piezoelectric Micro-machined Ultrasonic Transducer, pMUT)의 설계 연구가 진행되었다. 하나의 트랜스듀서로 광대역을 달성하는 방법 중 하나는 다공진 시스템으로 설계하는 것이다. 새로운 pMUT은 박막 구조의 앞면과 뒷면에 적절한 음향 구조를 추가하여 다공진 시스템을 구현하도록 설계되었다. 박막 앞쪽은 도파관 구조로 모델링된 방사 파트로, 박막 뒷쪽은 음향 공동으로 모델링된 패키징 파트로 이루어져있다. 박막 파트, 방사 파트, 패키징 파트로 구성된 새로운 pMUT은 집중 변수 모델로 설계되었으며, 최종적으로 유한요소해석으로 검증되었다. 최종 설계된 pMUT은 102 kHz ~ 132 kHz (-3 dB)의 주파수 대역을 달성하였다.

유한요소 모델 변수의 역 추정법을 이용한 생체의 물성 규명 (Biomechanical Characterization with Inverse FE Model Parameter Estimation: Macro and Micro Applications)

  • 안범모;김영진;신현정;김정
    • 대한기계학회논문집A
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    • 제33권11호
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    • pp.1202-1208
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    • 2009
  • An inverse finite element (FE) model parameter estimation algorithm can be used to characterize mechanical properties of biological tissues. Using this algorithm, we can consider the influence of material nonlinearity, contact mechanics, complex boundary conditions, and geometrical constraints in the modeling. In this study, biomechanical experiments on macro and micro samples are conducted and characterized with the developed algorithm. Macro scale experiments were performed to measure the force response of porcine livers against mechanical loadings using one-dimensional indentation device. The force response of the human liver cancer cells was also measured by the atomic force microscope (AFM). The mechanical behavior of porcine livers (macro) and human liver cancer cells (micro) were characterized with the algorithm via hyperelastic and linear viscoelastic models. The developed models are suitable for computing accurate reaction force on tools and deformation of biomechanical tissues.

초소형 고체 추진제 추력기의 내탄도 성능연구 (Internal Ballistic Analysis of Solid Propellant Micro-Thruster)

  • 양준서;이종광;권세진
    • 한국추진공학회:학술대회논문집
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    • 한국추진공학회 2007년도 제29회 추계학술대회논문집
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    • pp.215-218
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    • 2007
  • 고체추진제를 사용한 초소형 추력기의 내탄도 모델링과 성능예측에 관하여 기술하였으며, 특히 초소형화 되면서 고려해야하는 연소실 내의 열손실을 고려하였다. 추진제는 일반 HTPB-AP계열을 선택하였으며, 계산 모델은 간단한 1차원 축대칭 end-burner 모델로 정하였다. 연소실내의 화염에 노출되는 표면과 체적에 대한 비율을 변화시키면서 연소실 가스 온도, 압력, 추력을 계산하여 본 논문의 경우 열손실효과로 약 3%의 총역적 감소가 있음을 확인하였다.

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단층 다결정 실리콘 마이크로머시닝 기술로 제작된 정전형 마이크로 미러 어레이의 모델링 및 측정 (Modeling and Measurement of Electrostatic Micro Mirror Array Fabricated with Single Layer Polysilicon Micromachining Technology)

  • 민영훈;김용권
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 1997년도 추계학술대회 논문집 학회본부
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    • pp.612-614
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    • 1997
  • Silicon based micro mirror array is a highly efficient component for use in optical applications such as adaptive optical systems and optical correlators. A micro mirror array designed, fabricated and tested here is consisted of $5{\times}5$ single layer polysilicon, electrostatically driven actuators. In this paper, deflection characteristics and pull-in behavior of the actuators for analog control was studied and particularly, the influence of the residual stress in flexure beams for the restorative force of actuators was considered. The springs are modeled as a residual stress-free spring and a spring with residual stress. In calculation, a mirror with the residual stress-free springs has 30.3N/m spring constant and 31.1V pull-in voltage. On the other hand, a mirror with the stressed springs has 23.6N/m and 27.4V respectively. The experimental result, which is 20.5N/m and 25.5V, shows that the stressed springs ore well modeled.

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형상 축소된 연소기의 열손실 및 소염해석 모델 (Thermodynamic Modeling of Heat Loss and Quenching in a Down Scaled Combustor)

  • 이대훈;권세진
    • 대한기계학회논문집B
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    • 제26권7호
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    • pp.919-926
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    • 2002
  • Down scaled combustor undergoes increased heat loss that results in incomplete combustion or quenching of the flame as a consequence. Therefore, effect of enhanced heat loss should be understood to design a MEMS scale combustion devices. Existing combustion models are inadequate for micro combustors because they were developed for analysis of regular scale combustor where heat loss can be ignored during the flame propagation. In this research a combustion model is proposed in order to estimate the heat loss and predict quenching limit of flame in a down scaled combustor. Heat loss in the burned region is expressed in a convective form as a product of wall surface area, heat transfer coefficient and temperature difference. Comparison to the measurements showed satisfactory agreement of the pressure and temperature drop. Quenching is accounted for by introducing a correlation of quenching parameter and heat loss. The present model predicted burnt fraction of gases with reasonable accuracy and proved to be applicable in thermal design of a micro combustor.

Parametric Studies and Performance Analysis of a Biplane Micro Air Vehicle

  • Maqsood, Adnan;Go, Tiauw Hiong
    • International Journal of Aeronautical and Space Sciences
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    • 제14권3호
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    • pp.229-236
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    • 2013
  • This paper presents the experimental investigation of a biplane micro air vehicle. The effects of geometric parameters, gap, stagger, and decalage angle are investigated at low Reynolds number (~150,000) in a low-speed wind tunnel. A rigid flat plate with an aspect ratio of one and square planform shape is used to evaluate all three geometric parameters. The side dimension of the single flat plate is 0.15 m. The goal is to find an optimal biplane configuration that should exceed monoplane performance by generating high lift and flying as slow as possible, in order to capture high-quality visual recordings. This configuration will directly help to fly at a lower velocity and to make tighter turns that are advantageous in restricted environments. The results show that the aerodynamic performance of the biplane MAV is significantly enhanced through the combination of gap and stagger effects. A performance comparison demonstrates the superiority of the optimal biplane configuration compared to a monoplane in cruise and glide phases. Moreover, no significant compromise is found for the range, endurance, and climb performance.