• 한국전산유체공학회지
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• 제19권2호
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• pp.93-98
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• 2014

In the present study, CFD methods are applied in the design procedure of rotor blades in a axial-flow fan and the aerodynamic performances are predicted. The blade profiles initially determined by the free vortex method and empirical formula are modified to match the target value of the rotor work load through the analysis of 3D Navier-Stokes solver. The corrected shapes of the rotor blade showed the increase of the efficiency and the pressure simultaneously.

• 대한기계학회논문집B
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• 제20권11호
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• pp.3639-3648
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• 1996

The effect of 15% pinched diffuser in a centrifugal air compressor with a cascade airfoil diffuser on the aerodynamic performance is investigated using a numerical approach. The commercial CFD code for three-dimensional, turbulent, compressible flow fields is executed for various mass flow rates at a design speed which can be obtained as long as the calculation succeeds. The pinched diffuser is found to help improve the instability of flow within vaneless diffuser space, especially the reverse flow near shroud, and to change both stall/surge line and choking line to increase the surge margin. It is also found to generate more favorable increase of static pressure in diffuser region, and to increase the resulting pressure ratio and efficiency.

• 반도체디스플레이기술학회지
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• 제3권2호
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• pp.1-4
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• 2004

An experimental study was conducted on the optimal configuration and size of ADFL(Aerodynamic Focusing Lens) which used in modified ISPM(In-Situ Particle Monitoring). The particle counting efficiency has been known as a function of distance and size of ADFL, thus we varied these parameters to find out the optimum values. From a result of experiment, it was found that two lenses and 6mm space between them showed a maximum particle measuring efficiency. To apply this modified ISPM to semiconductor manufacturing field, we need more experiment about the pressure change, flow rate, and input particle size.

• 동력기계공학회지
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• 제17권3호
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• pp.35-43
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• 2013

Generally, the chassis of an indoor RAC is composed of a rear-guider and a stabilizer. The aerodynamic performance of a cross-flow fan is strongly influenced by the various design factors of the chassis of an indoor RAC. The purpose of this paper is to select the optimum design factors through the aerodynamic performance of a cross-flow fan. The design factors are the leading angle of a rear-guider (${\theta}_1$), a stabilizer setup angle(${\theta}_2$), a rear-guider clearance(${\epsilon}_1$), and a stabilizer clearance(${\epsilon}_2$), respectively. As a result, the optimum design factors of an indoor RAC can be presented as a combination of ${\theta}_1=33^{\circ}$, ${\theta}_2=55^{\circ}$, ${\epsilon}_1=6{\sim}8mm$, and ${\epsilon}_2=7mm$ through the analysis of a static pressure coefficient and a static pressure efficiency.

• Wind and Structures
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• 제31권1호
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• pp.15-20
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• 2020

The aircraft industry supports aviation by building aircraft and manufacturing aircraft parts for their maintenance. Fuel economization is one of the biggest concerns in the aircraft industry. The reduction in specific fuel consumption of aircraft can be achieved by a variety of means, simplest and more effective is the one to impose minor modifications in the aircraft main wing or the parts which are exposed to the air flow. This method can lead to a reduction in aerodynamic resistance offered by the air and have a smoother flight. The main objective of this study is to propose geometric design modifications on an existing aircraft wing which acts as a vortex generator and it can reduce the drag and increase lift to drag ratio, leading to lower fuel consumption. The NACA 2412 aircraft wing is modified and designed. Rigorous flow analysis is carried out using computational fluid dynamics based software Ansys Fluent. Results show that saw tooth modification to the main wing shows the best aerodynamic efficiency as compared to other modifications.

• 한국입자에어로졸학회지
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• 제13권2호
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• pp.53-63
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• 2017

As semiconductor process was highly integrated, particle contamination became a major issue. Because particle contamination is related with process yields directly, particles with a diameter larger than half pitch of gate should be controlled. PBMS (Particle beam mass spectrometry) is one of powerful nano particle measurement device. It can measure 5~500 nm particles at ~ 100 mtorr condition in real time by in-situ method. However its usage is restricted to research filed only, due to its big device volume and high price. Therefore aperture changeable aerodynamic lenses (ACALs) which can control particle focusing characteristics by changing its aperture diameter was proposed in this study. Unlike conventional aerodynamic lenses which changes particle focusing efficiency when operating condition is changed, ACALs can maintain particle focusing efficiency. Therefore, it can be used for a multi-monitoring system that connects one PBMS and several process chambers, which greatly improves the commercialization possibility of the PBMS. ACALs was designed based on Stokes number and evaluated by numerical method. Numerical analysis results showed aperture diameter changeable aerodynamic lenses can focus 5 to 100 nm standard particles at 0.1 to 10 torr upstream pressure.

• 동력기계공학회지
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• 제9권3호
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• pp.33-38
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• 2005

The aerodynamic performance of a cross-flow fan is strongly influenced by the various design factors of a rear-guider and a stabilizer. The purpose of this paper is to investigate the effects of a rear-guider and a stabilizer on the aerodynamic performance of a cross-flow fan. The design factors considered in this paper are a rear-guider clearance, a stabilizer clearance, and a stabilizer setup angle, respectively. This experiment was carried out with a constant revolution number of 700 rpm in a cross-flow fan installed in the fan tester. The static pressure, flowrate, torque, and revolution number were measured in this paper. Also, the pressure coefficient and the efficiency were analysed according to the various assembly conditions using a stabilizer setup angle, a stabilizer clearance, and a rear-guider clearance in the indoor room air-conditioner.

• 항공우주시스템공학회지
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• 제17권6호
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• pp.94-99
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• 2023

최근 신재생에너지는 주로 사용되는 화석연료의 부족과 환경문제로 풍력에너지와 태양에너지 자원으로 널리 사용되고 있다. 이런 상황에서 풍력에너지는 중요한 에너지원으로 떠오르고 있으며, 풍력 발전 시장은 전 세계적으로 급격한 성장을 보여주고 있다. 본 연구에서는 분리형 블레이드의 선행연구를 위해 일체형 블레이드 공력 설계로 고효율 풍력 터빈 블레이드를 설계를 수행하였다. 블레이드 에어포일은 NACA 4418로 적용하였고, 설계된 블레이드를 평가하기 위해 해석 결과와 비교하여 검증하였다.

• 한국음향학회지
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• 제36권2호
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• pp.89-99
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• 2017

멀티로터형 무인항공기는 군사용 목적뿐 아니라 항공 촬영 및 무인 택배 수단 등 민간 산업까지 그 활용 범위를 넓혀가고 있다. 무인항공기의 보다 폭넓은 활용을 위해서는 추진체인 프로펠러의 공력 효율 개선과 소음의 저감을 위한 연구가 선행되어야 하며, 이는 주어진 환경에서 공력 성능 및 소음을 예측할 수 있는 기술이 바탕이 되어야만 가능하다. 본 연구에서는 소형 무인항공기 프로펠러를 대상으로 공력 및 소음 예측 기법을 개발하고, 실제 측정을 통한 결과와의 비교를 통해 검증하였다. 분당 회전수의 변화에 따른 추력 및 토크와 주어진 위치에서의 주파수 스펙트럼 예측에서 모두 예측 기법의 신뢰성을 확보하였으며, 이를 통해 프로펠러의 형상 설계에 기반이 될 수 있는 기틀을 마련하였다.

• 대한기계학회논문집B
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• 제24권3호
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• pp.325-337
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• 2000

A study was done on the numerical and experimental analyses of the aerodynamic characteristics of a counter rotating axial fan. The numerical analysis uses the frequency domain panel method developed for the aerodynamic analysis of interacting rotating systems, which is based on the unsteady lifting surface panel method. Each stage of interaction involves the solution of an isolated rotor, the interaction being done through the Fourier transform of the induced velocity field. Numerical results showed good agreements with other experimental data for single and counter rotating propeller systems. And they were compared with the experimental results of the counter rotating axial fan studied in the present paper. The performance test was carried out based on the Korean Standard (KS B 6311). It was focused on the relative efficiency increase of a counter rotating system for a single rotating one, and effects of the axial distance between the front and rear rotors on overall fan performances were investigated. As a result, it was shown that the counter rotating axial fan has the efficiency 14% higher than the single rotating one at peak efficiency points.