• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.2
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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.

• Design & Manufacturing
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• v.16 no.3
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• pp.16-21
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• 2022

In order to reduce the weight of parts and materials for the development of high-efficiency engines in accordance with the strengthening of automobile fuel efficiency regulations, the existing casting material is changed to a iron plate material, and plastic processing and turning operations are performed to lighten the weight and reduce the manufacturing cost. Among the pulley components applied to the damper pulley, the HUB product was manufactured by plastic machining instead of the existing casting process, and the inspection standardized for automating the inner diameter and parallelism measurement of the turning result of the new hub part with improved quality, and the inspection system for this Development of design and operation software to automate the inspection of the inner diameter and parallelism of the hub was described. The representative specifications of the development equipment are a hub inner diameter 22mm inspection system, a three-point inspection system with a parallelism of 0.15mm on the top.

• Transactions of the Korean Society of Automotive Engineers
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• v.23 no.3
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• pp.352-359
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• 2015

This study investigates the analysis result of structure and fatigue due to the models of the hub space with bolt joint at wheel and the existence or nonexistence of hub ring as the part of suspension system of vehicle. As the static analysis result, the structural vulnerability can be found at hub bolt and the center of wheel at three models. Model 2 and 3 have nearly same deformation and model 1 can be endured at the least load among three models. As the fatigue analysis result, fatigue lives of three models are same at the severest load of SAE bracket history. As many screw threads of weak bolts are jointed in case of model 1, model 1 is shown to be the weakest at fatigue damage among three models. By the result of this study, model 1 with bolt joint becomes most weakest among three models. As model 2 with no hub ring and model 3 with hub ring have the nearly same states of analysis results, hub ring is shown to have no influence on the safety of automotive driving.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.39 no.2
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• pp.103-112
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• 2016

As supply chains are globalized, multinational companies are trying to optimize distribution networks using a hub and spoke structure. In this hub and spoke network structure, multinational companies locate regional distribution centers at hub airports, which serve demands in their corresponding regions. Especially when customers put higher priority on the service lead-time, hinterlands of international hub airports become ideal candidate locations for the regional hub distribution centers. By utilizing excellent airport and logistics services from hub airports, regional distribution centers in the hub airports can match supply with demand efficiently. In addition, regional hub distribution centers may increase air cargo volume of each airport, which is helpful in the current extremely competitive airport industry. In this paper, we classified locational preferences into three primary categories including demand, service and risk and applied the analytic hierarchy process methodology to prioritize factors of locational preferences. Primary preference factors include secondary factors. Demand factor contains access to current and prospect markets. Service factor comprises airport and logistics perspectives. Service factor in terms of airport operations includes secondary factors such as airport service and connectivity. Service factor in terms of logistics operations contains infrastructure and logistics operations efficiency. Risk factor consists of country and business risks. We also evaluated competitiveness of Asian hub airports in terms of candidate location for regional hub distribution centers. The candidate hub airports include Singapore, Hong Kong, Shanghai, Narita and Incheon. Based on the analytic hierarchy process analysis, we derived strategic implications for hub airports to attract multinational companies' regional hub distribution centers.

• Structural Engineering and Mechanics
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• v.30 no.4
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• pp.427-444
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• 2008

A mathematical model for the nonlinear dynamics of a rotating beam with flexible root attached to a rotating hub with elastic foundation is developed. The model is developed based on the large planar and flexural deformation theory and the potential energy method to account for axial shortening due to bending deformation. In addition the exact nonlinear curvature is used in the system potential energy. The Lagrangian dynamics and the assumed mode method is used to derive the nonlinear coupled equations of motion hub rotation, beam tip deflection and hub horizontal and vertical displacements. The derived nonlinear model is simulated numerically and the results are presented and discussed for the effect of root flexibility, hub stiffness, torque type, torque period and excitation frequency and amplitude on the dynamic behavior of the rotating beam-hub and on its stability.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.680-685
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• 2006

This paper describes the aeroelastic stability test of the small-scaled 'Next-Generation Blade(NRSB)' with NRSH (Next-Generation Hub System) and HCTH hingeless hub system in hover and forward flight conditions. Excitation tests of rotor system installed in GSRTS(General Small-scale Rotor Test System) at KARI(Korea Aerospace Research Institute) were tarried out to get lead-lag damping ratio of blades with flexures as hub flexure. MBA(Moving Block Analysis) technique was used for the estimation of lead-lag damping ratio. First, NRSB-1F blades with HCTH hub system, Then NRSB-1F with NRSH hub system were tested. Second, NRSB-2F blades with NRSH hub system were tested. Tests were done on the ground and in the wind tunnel according to the test conditions of hover and forward flight, respectively. Non-rotating natural frequencies, non-rotating damping ratios and rotating natural frequencies were showed similar level fir each cases. Estimated damping ratios of NRSB-1F, NRSB-2F with HCTH and NRSH were above 0.5%, and damping ratio increased by collective pitch angle increasement. Furthermore damping ratios of NRSB-2F were higher than damping ratios of NRSB-1F in high pitch angle. It was confirmed that the blade design for noise reduction would give observable improvement in aeroelastic stability compared to paddle blade and NRSB-1F design.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.8 s.113
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• pp.848-856
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• 2006

This paper describes the aeroelastic stability test of the small-scaled 'Next-generation Blade(NRSB)' with NRSH (next-generation hub system) and HCTH hingeless hub system in hover and forward flight conditions. Excitation tests of rotor system installed in GSRTS (general small-scale rotor test system) at KARI (Korea Aerospace Research Institute) were carried out to get lead-lag damping ratio of blades with flexures as hub flexure. MBA(moving block analysis) technique was used for the estimation of lead-lag damping ratio. First, NRSB-1F blades with HCTH hub system, then NRSB- 1F with NRSH hub system were tested. Second, NRSB-2F blades with NRSH hub system were tested. Tests were done on the ground and in the wind tunnel according to the test conditions of hover and forward flight, respectively. Non-rotating natural frequencies, non-rotating damping ratios and rotating natural frequencies were showed similar level for each cases. Estimated damping ratios of NRSB-1F, NRSB-2F with HCTH and NRSH were above 0.5%, and damping ratio increased by collective pitch angle increasement. Furthermore damping ratios of NRSB-2F were higher than damping ratios of NRSB-1F in high Pitch angle. It was confirmed that the blade design for noise reduction would give observable improvement in aeroelastic stability compared to paddle blade and NRSB-1F design.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.2
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• pp.98-105
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• 2005

This paper presents the result of the aeroelastic stability test of the small-scaled hingeless hub system with composite paddle blades in hover and forward flight conditions. Excitation tests of hingeless hub system installed in GSRTS(General Small-scale Rotor Test System) at KARI(Korea Aerospace Research Institute) were carried out to get lead-lag damping ratio of blades with flexures as hub flexure. MBA(Moving Block Analysis) technique was used for the estimation of lead-lag damping ratio. First, blades with metal flexures, then with composite flexures of the same dynamic properties of rotor system as metal one were tested. Tests were done on the ground and in the wind tunnel according to the test conditions of hover and forward flight, respectively. Composite flexures were found to have better damping characteristics over metal ones in the non-rotating vibration test, and it was confirmed that the use of composite flexures would give observable improvement in aeroelastic stability compared to metal ones in all test conditions.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2003.10a
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• pp.119-122
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• 2003

This report describes the procedure of detailed design and structural test for the composite flexure which is a part of the hingeless hub system. First, stacking sequence design for composite flexure was done, and structural analysis by using NASTRAN was made to verify structural stability and safety. Using FPS installed at KIMM, composite flexure was laid up and cured using a autoclave. Before rotor ground test, the basic structural tests such as a bench test, tensile strength test and shear strength test, for flexure, were accomplished. Through replacing existing metal hub part with new fabricated composite flexure, improvement of aeroelastic stability and weight reduction were achieved. This result will be applied to composite rotor system design fur helicopter.

• Korean System Dynamics Review
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• v.5 no.1
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• pp.111-126
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• 2004

Many countries in the North East Asia are competing with each other in order to become a centre of international logistics activities. The competition to become a hub port in Far East region is now fierce. The anticipated investments on improving port facilities and attracting the mega carriers are immense for all the ports in the region and the extent of the effort could cripple the local ports and region's economy given the limited financial resources. It is, however, impossible to avoid the disastrous possibility that the massive investments could be channeled into the port, which will never become a hub port, as no port is ready to currently admit defeat and settle as a small regional port. In an attempt to minimise such disastrous waste of resources, ports need to verify the eligibility of their own. This paper tests a system dynamics model using the Port of Busan to understand and illustrate the principle guideline of investment decision making for ports.