• 한국소음진동공학회논문집
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• 제23권2호
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• pp.105-111
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• 2013

Whirl tower test is conducted basically during helicopter rotor system development process. And for whirl tower test of rotor hub system, new design blade or existing blade which is remodeled for new rotor hub system is used. Because of simple shape and efficient aerodynamic characteristic, BO-105 helicopter blade is used for helicopter rotor hub development project widely. Originally BO-105 blade is used for hingeless hub system and blade root is used to flexure. So flap stiffness and lag stiffness at blade root area is relatively low compare with airfoil area. So, in order to apply the BO-105 blade to bearingless hub, blade root area have to be reinforced. And in this process, blade root area's section property is changed. In this paper, we suggest reinforcement method of BO-105 blade root area and study dynamic characteristic of bearingless rotor system with reinforcement BO-105 blade.

• 소성∙가공
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• 제21권7호
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• pp.397-402
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• 2012

The flange hub is a main component in an automotive steering system. In general, the flange hub are fabricated by mechanical machining, which is a process where material waste is inevitable. It is well-known that a net-shape cold forging cannot only reduce material waste but can also improve the mechanical strength of the final product. Thus, a forging process design was conducted for production of a flange hub. Significant spring-back occurs around the flange due to its small thickness in conjunction with the residual stresses after forging. In order to achieve the required dimensional accuracy, a process design with appropriate spring-back control is needed. In this study, a modification of the forging die was designed based on FE analysis with the purpose of spring-back compensation. Four kinds of different die designs were evaluated and the optimum design has two times less spring-back than the initial design. The compensation angle of the optimum design is 0.5 degrees. The results have been experimentally confirmed by cold forging of a flange hub and comparing the amount of spring-back between the actual component and the FE analysis.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2005년도 춘계학술대회
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• pp.25-32
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• 2005

The aerodynamic loads at the blade hub and the drive shaft for 1MW horizontal axis wind turbine are calculated numerically. The geometric shape of the blade such as chord length and twist angle can be obtained fran the aerodynamic optimization procedure. Various airfoil data, that is thick airfoils at hub side and thin airfoils at tip side, are distributed along the spanwise direction of the rotor blade. Under the wind data fulfilling design load cases based on the IEC61400-1, all of the shear forces, bending moments at the hub and the low speed shaft of the drive train are obtained by using the FAST code. It shows that shear forces and bending moments have a periodic. trend. These oscillating aerodynamic loads will lead to the fatigue problem at both of the hub and drive train From the load analysis the maximum shear forces and bending moments are generated when wind turbine generator system operates in the case of the extreme speed wind condition.

• 한국유체기계학회 논문집
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• 제14권3호
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• pp.59-64
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• 2011

Wind turbine frame will be required to be longer, lighter, more reliable and more consistent. Therefore it is necessary to lose weight of the wind turbine hub. Light-weight Design of a wind turbine is required to be at least 20 years. Therefore, this paper investigates the development for wind turbine rotor hub using design of topology optimization. The model is a pitch regulated wind turbine with three rotor blades where the main frame is made of nodular iron. For optimization, calculating stresses based on displacements and based on these data to carry out a verification of static and fatigue strength carried out. For this verification, two kind of analysis is used. One is static analysis and the other is fatigue analysis. Then the rotor hub of wind turbine frame is optimized using topology method.

• 한국정밀공학회지
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• 제15권2호
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• pp.28-34
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• 1998

Powder metallurgy processes are able to form Net-Shape products and have been widely used in the production of automobile parts to improve its productivity. However, because of pores in powder products, the toughness of powder products are generally poor. Therefore, forged products are used in parts which suffer severe fatigue loads. In this paper, the choice of powder materials and production processes such as mixing, compaction, sintering, heat treatment to produce automobile spline hub are studied. Three type of materials are selected and processed and its microstructure and properties are investigated by tensile test, compression ring test, and impact test. Materials and processing methods are selected from the results. Finally, experimental spline hubs are manufactured by selected processes from selected powders and proved by torsional durability test.

• 한국자동차공학회논문집
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• 제14권1호
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• pp.39-47
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• 2006

Recent trend in pursuit of high performance and effectiveness for automotive cooling system has changed the application of material for impeller of automotive water pump from metal to high ability engineering resin, which can achieve optimization of design of impeller geometry and realize lightweight high efficiency water pump. Closed type water pump improves hydraulic loss of fluid through the clearance between volute casing and impeller compared with that of the existing open type water pump(Although closed type is heavier than open type for the same size and same material, adoption of plastics can solve the problem.). In the present study, the characteristics of hydraulic performance of closed type water pump were investigated with respect to the angle between shroud and hub of impeller and the shape of discharge port of volute casing. Performance tests were carried out for 4 cases, that is, for 2 impellers and 2 casings. The modification of shape of only discharge port can enhance the hydraulic performance by 10 percent and the pump efficiency by 4-6 percent.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2012년도 춘계학술대회 논문집
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• pp.622-627
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• 2012

During helicopter rotor system development process, whirl tower test is conducted basically. For conducting whirl tower test during bearingless hub development process, design new blade or using existing blade with repair or remodeling. Because simple shape and efficient aerodynamic characteristic, BO-105 blade is used for hub system development widely. Originally BO-105 blade is used for hingeless hub, ho flap stiffness and lag stiffness on blade root area is relatively low. So applying BO-105 blade to bearingless hub whirl tower test, root area have to be reinforce. In this process, blade root area's section property will be changed. In this paper, suggest reinforcement method of BO-105 blade root area and study dynamic characteristic of bearingless rotor system with reinforcement BO-105 blade.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2005년도 제25회 추계학술대회논문집
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• pp.34-39
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• 2005

본 논문에서는 3차원 초음속 노즐 형상 변수에 따른 부분입사형 터빈의 유동 및 성능 특성을 알아보기 위하여 3차원 노즐 형상 변수를 노즐 모양 및 노즐 출구 단면 형상으로 설정하여 전산해석을 실시하였다. 먼저 노즐 모양에 따른 유동 및 성능 특성을 비교해 본 결과, 사각형 노즐이 원형 노즐보다 축방향 간극내에서 발생하는 전압력 손실이 적었으며, 이로 인하여 파워가 약 1.5% 증가하였다. 다음으로 사각형 노즐출구단면의 면적에 따른 유동 및 성능 특성을 비교해 본 결과, 노즐 출구 단면과 로터의 hub/tip 사이의 간극과 노즐간의 간격이 터빈 성능에 크게 영향을 줌을 확인할 수 있었다.

• 한국항공우주학회지
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• 제39권5호
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• pp.424-432
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• 2011

원심압축기 임펠러의 최적화연구를 수행하기 위하여 임펠러의 형상변수와 설계변수에 관한 연구를 수행하였다. 최적화된 결과로부터 성능향상이 달성되었는지를 평가하기 위하여 기존에 실험되어진 임펠러를 선택하였으며, 이 임펠러에서 최적화를 위한 설계변수를 선정하였다. 임펠러 유로에서 허브와 쉬라우드에서의 형상은 베지어곡선으로 재설계되었다. 또한 임펠러 허브와 팁에서의 블레이드 캠버선도 베지어곡선으로 표현하였다. 각각의 형상곡선은 6-8개의 조정점으로 충분히 일치하는 곡선을 얻게 되었으며, 이 중 형상의 변화에 큰 영향을 미치는 조정점을 선택하여 8개의 설계변수로 최적화가 가능함을 보여주었다. 따라서 기존에 사용되고 있는 원심압축기 임펠러의 점 데이터를 활용하여 최적화 형상을 위한 연구가 진행될 수 있음을 보여주었다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2010년도 추계학술대회 논문집
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• pp.781-782
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• 2010