• 제목/요약/키워드: 누설모델

검색결과 120건 처리시간 0.024초

평면 매립형 레이저 다이오드의 전기적 등가회로 모델 (Design of Electrical equivalent circuit of Planar Buried Heterostructure Laser Diode)

  • 김정호;박동국
    • 한국정보통신학회논문지
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    • 제10권4호
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    • pp.718-723
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    • 2006
  • 초고속 정보통신망의 구축에 있어 광모듈은 중요한 부분을 차지하고 있다. 그 중에서 광원인 레이저 다이오드는 온도에 변화에 대해 성능이 크게 좌우되므로, 많은 연구가 이루어지고 있다. 본 논문은 평면 매립형 레이저 다이오드를 비율 방정식에 의하여 전기적 등가회로로 변환하였다. 그리고, 누설 경로에 해당하는 활성층 바깥 영역을 다이오드와 두 개의 트랜지스터로 등가화한 후, 시뮬레이션을 통해 누설전류를 해석하였다. 시뮬레이션을 통해 누설전류를 줄이기 위한 전류차단층의 도핑농도를 조사하였다.

축류 회전차 익말단 틈새유동에 대한 수치해석(II) - 틈새변화 및 영각변화에 따른 누설와류의 변화 - (Numerical Analysis on the Blade Tip Clearance Flow in the Axial Rotor (II) - Variation of Leakage Vortex with Tip Clearance and Attack Angle -)

  • 노수혁;조강래
    • 대한기계학회논문집B
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    • 제23권9호
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    • pp.1106-1112
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    • 1999
  • Substantial losses behind axial flow rotor are generated by the wake, various vortices in the hub region and the tip leakage vortex in the tip region. Particularly, the leakage vortex formed near blade tip is one of the main causes of the reduction of performance, generation of noise and aerodynamic vibration in downstream. In this study, the three-dimensional flow fields in an axial flow rotor were calculated with varying tip clearance under various flow rates, and the numerical results were compared with experimental ones. The numerical technique was based on SIMPLE algorithm using standard $k-{\varepsilon}$ model(WFM) and Launder & Sharma's Low Reynolds Number $k-{\varepsilon}$ model(LRN). Through calculations, the effects of tip clearance and attack angle on the 3-dimensional flow fileds behind a rotor and leakage flow/vortex were investigated. The presence of tip leakage vortex, loci of vortex center and its behavior behind the rotor for various tip clearances and attack angles was described well by calculation.

건축물 구획실간 틈새에서의 누설유동에 대한 수치모델 연구 (Study on Numerical Model of Leakage Flow at Gap between Compartments in a Building)

  • 김정엽;김지석
    • 설비공학논문집
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    • 제25권10호
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    • pp.562-567
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    • 2013
  • 1D-numerical analysis of the network algorithm with the orifice equation for the relationship between pressure difference and flowrate has been mostly used to analyse leakage flow at the gap. In this study, a 3D-numerical method applying momentum loss model to the gap region in the computational domain is represented to reflect effectively the effect of leakage flow by determining the proportion of pressure difference to air passage velocity. While the 3D-numerical method is verified through the computation of the two compartments model, the numerical analysis of the stack effect in a building stairway is performed. As the temperature of air outside drops, the pressure in the upper stairway and leakage flowrate through the gap in the door rise. The change of gap area does not have an effect on pressure in the stairway for the analysis conditions.

신경망무고장모델과 이중퍼지로직을 사용한 냉방기 고장진단 알고리즘 (Fault Diagnosis Algorithm of an Air-conditioning System by using a Neural No-fault Model and a Dual Fuzzy Logic)

  • 한도영;정남철
    • 설비공학논문집
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    • 제18권10호
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    • pp.791-799
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    • 2006
  • The fault diagnosis technologies may be applied in order to decrease the energy consumption and the maintenance cost of an air-conditioning system. In this paper, a fault diagnosis algorithm was developed by using a neural no-fault model and a dual fuzzy logic. Five different faults, such as the compressor valve leakage, the liquid line blockage, the condenser fouling, the evaporator fouling, and the refrigerant leakage of an air-conditioning system, were considered. The fault diagnosis algorithm was tested by using a fault simulation facility. Test results showed that the algorithm developed for this study was effective to detect and diagnose various faults. Therefore, this algorithm may be practically used for the fault diagnosis of an air-conditioning system.

누설유량과 회전체동역학적 성능을 고려한 래버린스 씰 설계 (Labyrinth Seal Design Considering Leakage Flow Rate and Rotordynamic Performance)

  • 문민주;이정인;서준호
    • Tribology and Lubricants
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    • 제39권2호
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    • pp.61-71
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    • 2023
  • This study proposes a procedure for designing a labyrinth seal that meets both leakage flow rate and rotordynamic performance criteria (effective damping, amplification factor, separation margin, logarithmic decrement, and vibration amplitude). The seal is modeled using a one control volume (1CV) bulk flow approach to predict the leakage flow rate and rotordynamic coefficients. The rotating shaft is modeled with the finite element (FE) method and is assumed to be supported by two linearized bearings. Geometry, material and operating conditions of the rotating shaft, and the supporting characteristics of the bearings were fixed. A single labyrinth seal is placed at the center of the rotor, and the linearized dynamic coefficients predicted by the seal numerical model are inserted as linear springs and dampers at the seal position. Seal designs that satisfy both leakage and rotordynamic performance are searched by modifying five seal design parameters using the multi-grid method. The five design parameters include pre-swirl ratio, number of teeth, tooth pitch, tooth height and tooth tip width. In total, 12500 seal models are examined and the optimal seal design is selected. Finally, normalization was performed to select the optimal labyrinth seal designs that satisfy the system performance requirements.

영광-1, 2호기 2차계통 복수기누설의 이론적 분석 및 영향평가 (Theoretical Analysis and Effect of Condenser In-leakage in the Secondary Systems of YGN-1, 2)

  • Suk, Tae-Won;Lee, Yong-Woo;Kim, Hong-Tae;Park, Sang-Hoon
    • Nuclear Engineering and Technology
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    • 제23권3호
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    • pp.299-305
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    • 1991
  • 복수기를 통한 해수유입은 증기발생기내에 부식환경을 조성시키게 한다. 이론적 분석을 통하여 복수기누설시에 해수증의 불순물인 염소가 2차계통내에 누적되는 경향을 영광원전을 모델로하여 평가하였다. 분석결과 해수누설시에 고농도의 염소가 증기발생기내에 누적되는 것으로 나타났으나, 이는 증기 발생기내의 수질을 산성분위 기로 조성시킬 것으로 판단되었다. 복수기의 최대허용 설계누설(0.5 gpm)시에는 증기발생기 취출수량을 최대로 늘리고, 복수기정화계통을 가동하더라도 증기발생기에 2.3 ppm 및 복수기집수정에 0.6 ppm의 염소가 누적되는 것으로 나타났다. 또한 증기발생기에서의 염소농축계수는 아래와 같이 전적으로 취출수량 및 정화계통효율에만 의존하는 것으로 나타났으며,(equation omitted)취출수 및 정화계통은 2차계통내의 불순물을 제거하는데 효과적인 것으로 평가되었다.

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CFD를 사용한 터보기계 비접촉식 실의 누설량 예측 (Prediction of Non-Contact-Type Seal Leakage Using CFD)

  • 하태웅
    • 한국유체기계학회 논문집
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    • 제9권3호
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    • pp.14-21
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    • 2006
  • Leakage reduction through annular type seals of turbomachinery is necessary for enhancing their efficiency and the precise prediction method of seal leakage is needed. The analysis based on Bulk-flow concept has been mainly used in predicting seal leakage. However, full Navier-Stokes Equations with turbulent model derived in the seal flow passage have to be solved for improving the prediction of seal leakage. FLUENT 6 which is commercial CFD(Computational Fluid Dynamics) code based on FVM(Finite Volume Method) and SIMPLE algorism has been used to analyze leakage of various non-contact-type seals in this presentation. Comparing with the results of Bulk-flow model analysis and experiment, the result of CFD analysis shows good agreement with that of existing theoretical analysis for the incompressible grooved seal and compressive plain and staggered seal. The CFD analysis also shows improvement on the leakage prediction of the incompressible plain seal and compressive see-through-type labyrinth seal.

고정자 권선 사양에 따른 10kW급 고속 유도전동기의 전자기적 특성 및 가진력 분석 (Electromagnetic Characteristic and Excitation Force Analysis of 10kW High Speed Induction Motor According to Stator Winding Specifications)

  • 이지영;장대규;장정환
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2015년도 제46회 하계학술대회
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    • pp.748-749
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    • 2015
  • 본 논문에서는 권선사양에 따른 10kW급 동 다이캐스팅 고속 유도전동기의 전자기적 특성과 전기기기의 진동을 발생시키는 고정자 치의 가진력을 분석하였다. 회전자 모델과 코일의 점적률은 일정하게 유지하면서 턴 수, 코일단면적, 고정자 슬롯의 형상을 변경하였다. 이에 따라 1, 2차 측 저항과 누설리액턴스 성분이 변화함을 확인하였고, 저항과 누설리액턴스 성분의 변화가 유도전동기의 토크, 자속밀도, 효율 특성 및 고정자 치의 가진력에 미치는 영향에 대해 분석하였다.

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3차원 CFD를 사용한 환상 실의 누설량 예측 (Prediction of Annular Type Seal Leakage Using 3D CFD)

  • 석희수;하태웅
    • Tribology and Lubricants
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    • 제25권3호
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    • pp.150-156
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    • 2009
  • Precise leakage prediction for annular type seals of turbomachinery is necessary for enhancing their efficiency and various prediction methods have been developed. As the seal passage is designed intricately, the analysis based on Bulk-flow concept which has been mainly used in predicting seal leakage is limited. In order to improve the seal leakage prediction, full Navier-Stokes Equations with turbulent model derived in the seal flow passage have to be solved. In this study, 3D CFD (Computational Fluid Dynamics) analysis has been performed for predicting leakage of various non-contact type anular seals using FLUENT. Compared to the results by Bulk-flow model analysis, experiment, and 2D CFD analysis, the result of 3D CFD analysis shows improvement in predicting seal leakage, especially for the parallel grooved pump seal.