• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2004년도 학술대회지
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• pp.212-219
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• 2004

The effect of frequency and amplitude of the OWC (Oscillating Water Column) motion on the nonlinear reaction forces in an air duct arc studied experimentally. Experimental OWC model is idealized as a simple circular cylinder with an orifice type air duct located at the middle of the top rid. Reaction forces due to forced heave oscillation are measured and analyzed. By subtracting the effect of inertia forces and restoring forces, pneumatic damping force and added spring force are deduced. The effects of the frequency and amplitude of the heave motion are discussed. Also, the effects of solidity of the duct on the reaction forces are discussed.

• 조명전기설비학회논문지
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• 제13권4호
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• pp.21-26
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• 1999

지하공간에 있어 자연채광의 도입 효과는 쾌적한 실내 조명환경의 조성과 함께 인공조명 에너지 절감에 따른 실내조명 전력부하를 줄일 수 있을 것이다. 본 논문은 지하공간 Perimeter Occupied Zone에 있어 자연채광 에너지의 적극적 활용을 목적으로 채광덕트 시스템의 이용가능성을 제시하였으며, 컴퓨터 시뮬레이션을 위한 실내면의 상오반사 특성을 고려한 수치해석 프로그램을 개발하였다.

• 국제학술발표논문집
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• The 10th International Conference on Construction Engineering and Project Management
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• pp.645-652
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• 2024

Building Information Modeling (BIM) involves the integration of equipment information and component parameters across various engineering disciplines. The complex processes during model construction can lead to human errors. Furthermore, design changes often occur at various stages of the building's lifecycle, requiring designers and modelers to make timely modifications, resulting in significant costs and time consumption. Mechanical, electrical, and plumbing (MEP) design is considerably more complex than architectural design. Therefore, this study focuses on the automatic generation of a heating, ventilation, and air conditioning (HVAC) ductwork model with MEP design through BIM. Dynamo, a visual programming language (VPL), offers features such as arrangement, connectivity, and scalability. Thus, this research applied Dynamo to develop the Automatic Ductwork BIM Model Generation System. The BIM model generated by the system facilitates collaborative efforts and enables the analysis of HVAC System Conflicts. The system extracts coordinates for air handling units, supply air, and exhaust air outlets. The equipment is automatically positioned based on these coordinates, and the corresponding duct paths are generated by reading CAD files. At each duct connection point, appropriate fittings are fabricated according to specifications and dimensions. The duct system is configured with distinct colors, and the results are visualized in Revit, facilitating HVAC system clash detection in the future. This study undertakes a real project to validate the proposed system and processes and assesses its impact on modeling efficiency, real-time responsiveness, and accuracy, realizing automated ductwork generation.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 춘계학술대회 논문집
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• pp.919-922
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• 2008

The objective of this study is to design the full-scale fire test facility of the railroad vehicle with CFD simulation. In the results, the step expansion system should be good enough for the measuring system. Uniform flow is achieved at eight-to-ten diameters of the expanded duct behind the step for moderate expansion ratios($D_{orifice}/D_{duct}$ = 2 being a good choice). To optimization of the fire products collector system with 5 dampers, the additional CFD simulation was also carried out. These results will be help for the railroad fire safety research.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2005년도 제24회 춘계학술대회논문집
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• pp.219-224
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• 2005

본 연구는 CRW형식 무인항공기 추진시스템의 밸브 작동을 고려한 비행모드에 따른 천이성능특성을 파악하기 위해 SIMULINK를 이용하여 모델링 하였다. 주 엔진시스템의 천이모사에는 ICV 방법이 적용되였다. 그리고 밸브 시스템은 로터리 덕트와 메인 덕트로 빠져나가는 유량을 제어하는 시스템으로서 밸브를 통해 로터리 덕트로 빠져나가는 유량과 메인 덕트를 빠져나가는 유량이 합은 터빈의 출구 유량과 같다는 가정하에 수행 되었으며, 이때 밸브각 변화에 따른 손실, 유량 및 유효 면적 등이 고려되었다. 성능해석은 비행 천이 영역인 고도 1Km 비행 마하수 0.1에서 엔진최대회전수시 회전익 모드에서 고정익 모드로 변환시외 고정익 모드에서 회전익 모드로 변환 경우들이 수행되였다.

• 대한기계학회논문집B
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• 제22권2호
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• pp.139-152
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• 1998

In the present study, the flow characteristics of developing laminar oscillatory flows in a square -sectional 180 deg. curved duct are investigated experimentally. The experimental study using air in a square-sectional 180 deg. curved duct is carried out to measure velocity distributions with a data acquisition and LDV (Laser Doppler Velocimetry) processing system. In this system, Rotating Machinery Resolver (RMR) and PHASE program are used to obtain the results of unsteady flows. The major flow characteristics of developing oscillatory flows are found by analyzing velocity curves, mean velocity profiles, time-averaged velocity distribution of secondary flow, wall shear stress distributions, and entrance lengths. In a lower dimensionless angular frequency, the axial velocity distribution of laminar oscillatory flow in a curved duct shows a convex shape in a central part and axial symmetry. The maximum value of wall shear stress in a lower dimensionless angular frequency is located in an outside wall, but according to increasing the dimensionless angular frequency, the maximum of wall shear stress is moved to inner wall. The entrance lengths of laminar oscillatory flows in a square-sectional 180 deg. curved duct is obtained to 90 deg. of bended angle of duct in this experimental conditions.

• 한국추진공학회지
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• 제7권4호
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• pp.19-26
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• 2003

본 논문에서는 팁제트 로터를 사용한 CRW 비행체의 추진시스템에 대한 개념연구 결과를 다루었다. 비행체 중앙에 위치한 엔진으로부터 배기가스를 로터나 주 추력노즐까지 공급하기 위해서 길고 복잡한 내부덕트 시스템이 필요하며 배기가스 분배장치 등이 필요하다. 추진시스템의 성능해석을 위해 엔진운전특성과 내부덕트 시스템 특성을 함께 해석하였다 본 연구에서는 회전익모드에서 내부덕트 시스템의 형상변화에 따른 엔진 및 전체 추진시스템의 운전특성을 분석하여 추진시스템 설계를 위한 중요설계변수를 도출하였으며 파라매트릭 연구를 수행하여 향후 설계방향설정에 기여하였다.

• 한국추진공학회지
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• 제9권3호
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• pp.127-132
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• 2005

본 연구는 CRW형식 무인항공기 추진시스템의 밸브 작동을 고려한 비행모드에 따른 천이 성능 특성을 파악하기 위해 SIMULINK를 이용하여 모델링 하였다 그리고 밸브 시스템은 로터리 덕트와 메인덕트로 빠져나가는 유량을 제어하는 시스템으로서 밸브를 통해 로터리 덕트로 빠져나가는 유량과 메인덕트를 빠져나가는 유량의 합은 터빈의 출구 유량과 같다는 가정 하에 수행되었으며, 이때 밸브 각 변화에 따른 손실, 유량 및 유효 면적 등이 고려되었다. 성능 해석은 비행 천이 영역인 고도 1km 비행 마하수 0.1에서 엔진 최대회전수시 회전익 모드에서 고정익 모드로 변환되는 경우와 고정익모드에서 회전익 모드로의 변환되는 경우들이 수행되었다.

• 한국유체기계학회 논문집
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• 제19권5호
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• pp.12-19
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• 2016

In present study, a parametric study of a centrifugal compressor with inlet treatment has been performed numerically using three-dimensional Reynolds-averaged Navier-Stokes equations. The shear stress transport turbulence model was used for analysis of turbulence. The finite volume method and unstructured grid system were used for the numerical solution. Tested parameters were related to the geometry of the inlet duct. It was found that the application of circumferentially distributed holes in the inlet duct improves operational stability of the compressor compared to that with conventional inlet duct.

• 한국전산유체공학회지
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• 제2권2호
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• pp.44-50
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• 1997

Accurate simulation of jet plume exhausting into the open space as well as onto the opposing wall is of interest both numerically and physically; the latter, from a system designer's point of view. In the current work, Navier-Stokes computation is undertaken to capture the flow pattern of a supersonic jet impinging onto a rectangular duct which deflects the vertical jet horizontally. Of particular interest are the flow structure in the jet exhaust area, pressure pattern and the magnitude of pressure force at the bottom wall. Usefulness of present characteristic boundary condition applied at the exiting plane of the duct is demonstrated by capturing such complex flow structures for different lengths of the deflection duct.