• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.6
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• pp.612-619
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• 2010

In this paper, an elastomeric bearing for a helicopter rotor hub is designed using nonlinear finite element method. The elastomeric bearing is the main component of the helicopter rotor hub that acts as a hinge to three motions(flapping, lagging and pitching) of rotor blade. The elastomeric bearing consists of rubber and metal plates. The stiffness design of the elastomeric bearing is important because elastic deformation of rubber is served to hinge. Accordingly, the elastomeric bearing is designed to satisfy the stiffness requirements for rotor hub bearing. In this study, a FE model generation algorithm is developed and stiffness characteristic of a rubber plate is analyzed for an efficient design of the spherical elastomeric bearing. It is proven that the elastomeric bearing satisfies stiffness requirements of the spherical bearing for a helicopter rotor hub.

• Journal of Information Technology Services
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• v.13 no.4
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• pp.341-357
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• 2014

Service R&D that adds high value to existing products and service by scientification, IT convergence, intellectualization is a core business of creative economy. It is necessary to examine the service R&D revitalization plan by establishing service R&D hub researching the service R&D because a shortage of facility and infrastructure makes impossible to turn ideas into products (service). This research aims at establishing the implementation plan of service R&D hub that invigorates local service industries and contributes to carry out the plan. Service R&D hub is a focal point of service R&D activities which inter-connects service R&D activities distributed across ministries of central government and fields of studies, and which invigorates service R&D activities and enhances competitive power of service industries in Korea. It is necessary to establish main hub like Service Engineering Research Center in Japan and Fraunhofer IAO in Germany which take the lead in national service R&D activities, and make it build the solid foundation of service R&D activities in public sector and also create service innovation ecosystem. Considering the interdisciplinary characters of service R&D, it is essential to establish additional sub-hubs to meet a variety of demands of service R&D. It is also necessary to establish 'Living Lab', an open innovation system, which connects research institutions, universities, and corporates to make them target the specific fields of their own, and enhance open R&D and innovation in service industries.

• Transactions of Materials Processing
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• v.17 no.2
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• pp.124-129
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• 2008

Net shape forging technologies give many effects into the costs and qualities for the finished products. So, the studies to reduce the additional machining amount are very important in forging industry. Specially, there are two main topics in cold forging industry, such as, tool life and precision forging. In this study, new forging technique was proposed to eliminate the machining process for fixing up the length and improve the lead accuracy of gear. The luck-up hub is manufactured through many processes, such as upsetting, piercing and direct extrusion. The gear is formed in direct extrusion process; however, lead accuracy of the gear is over allowance limit. Therefore, the additional sizing process must be added. In this study, process design for closed-die forging of a lock-up hub used for a component of automobile transmission was made using three-dimensional finite element simulations, and the strain distributions and velocity distributions are investigated through the post processor. The rigid-plastic finite-element method for back pressure forging has been used in order to reduce development time and die cost. Using the FEM simulation, we found the optimum value of back pressure. The prototypes of lock-up hub parts were forged into the net-shape. In the experiment, lead precision of tooth are measured by the CCMM(Contact Coordinate Measuring Machine). The dimensional accuracy of forged part was improved up to the 40% when back press was applied.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.05a
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• pp.163-166
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• 2005

A hole expansion process is an important process in producing a hub-hole in a wheel disc of a vehicle. In this process, the main parameter is the formability of a material that is expressed as the hole expansion ratio. The hub-hole expansion process is different from conventional forming processes or hole flanging processes from the view-point of its deformation mode and forming of a thick plate. In the process, a crack is occurred in the upper edge of a hole as the hole is expanded. Since prediction of the forming limit by hole expansion experiment needs tremendous time and effort, an appropriate fracture criterion has to be developed fur finite element analysis to define forming limit of the material. In this paper, the hole expansion process of a hub-hole is studied by finite element analysis with ABAQUS/standard considering several ductile fracture criteria. The fracture mode and hole expansion ratio is compared with respect to the various fracture criteria. These criteria do not predict its fracture mode or hole expansion ratio adequately and show deviation from experimental results of hole expansion. A modified ductile fracture criterion is newly proposed to consider the deformation characteristics of a material accurately in a hole expansion process. A fracture propagation analysis at the hub-hole edge is also performed for high accuracy of prediction using the new fracture criterion proposed.

• Transactions of the Korean hydrogen and new energy society
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• v.35 no.2
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• pp.162-167
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• 2024

Fossil fuels have been main energy source to people. However, enormous amount of CO₂ was emitted over the world , resulting in global climate crisis today. Recently, solid oxide electrolyzer cell (SOEC) is getting attention as an effective way for producing H₂, a clean energy resource for the future. Also, SOEC could be applicable to reverse water-gas shift reaction process due to its high-temperature operating condition. Here, SOEC system was utilized for both H₂ production and CO₂ reduction process, allowing product gas composition change by controlling operating conditions.

• Journal of Arbitration Studies
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• v.29 no.4
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• pp.101-120
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• 2019

This study examines the development strategies of the arbitration industry in Singapore and Hong Kong, and its purpose is to provide implications for the development of the arbitration industry in South Korea. The main strategies implemented by Singapore and Hong Kong to develop the arbitration industry are as follows: first, improvement of the arbitration law system; second, active support of the government for promoting the arbitration industry; third, build up of an effective arbitration expert training system; and fourth, an arbitration-friendly attitude of the court. In order for South Korea to become an international arbitration hub in Northeast Asia, it is necessary to refer to the above-mentioned strategies. In addition, South Korea needs to develop marketing strategies that can differentiate itself from Singapore and Hong Kong, such as the development of an arbitration system in connection with the 4th Industrial Revolution, differentiation of the disputes sector, use of geographical advantages and a penetration pricing strategy, and support of the Korean Commercial Arbitration Board. In terms of marketing strategy, there are few studies on the development strategy of the arbitration industry in South Korea. In this respect, this study has academic value and differentiation.

• The KSFM Journal of Fluid Machinery
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• v.3 no.4 s.9
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• pp.38-43
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• 2000

Recently, KARI(Korea Aerospace Research Institute, Korea) and CIAM(Central Institute of Aviation Motors, Russia) have made an effort in developing a centrifugal compressor for a small gas turbine engine as part of a collaboration program. This compressor has been designed as a sub-component for an axial-centrifugal compression system for a small turbo-shaft engine aiming adiabatic efficiency higher than 0.81. The geometrical design requirement imposes restrictions to have high inlet hub-to-tip ratio and inlet swirl flow. In this study, the compressor has been designed using the generalized experimental data established from those compressors having pressure ratio of 3.7 to 5. From this generalized empirical correlation, desirable values of design parameters could be obtained. Subsequently, quasi-3D and 3D viscous flow analyses have been performed to ensure the adopted methodology. It is expected that the centrifugal compressor provides total pressure ratio of 4.89, corrected mass flow-rate of 1.64kg/sec, and adiabatic efficiency of 0.815 with inlet hub-to-tip ratio of 0.641. These relatively high total pressure ratio and inlet hub-to-tip ratio are the main distinctive features in this design. Besides, one of the main features of this centrifugal compressor is the adoption of a double-row bladed diffuser to effectively decelerate the transonic flow leaving the impeller. The compressor has been manufactured and will be tested in the near future.

• THE INTERNATIONAL COMMERCE & LAW REVIEW
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• v.16
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• pp.117-154
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• 2001

The objective of the study is to propose to the strategy to make korean main ports to international logistics center in Northeast Asia. so this study's construction is constructed four steps. First, analysis the environment of economy, business and logistics industry in Northeast Asia. Second, analysis the constructions and characters of Free Zone Act. Third, analysis of Korean Government's policy about Free Zone. Forth, propose the growing strategy of Free Zone. In 1999 Northeast Asia was adopted in Korea, which will facilitate the process and strengthen the international logistics capability as a international logistics hub in Northeast Asia. But only adoption in the point of law is not enough to growing korean main seaport and airport to a international logistics hub. so various strategies are needed. In this study, we propose the growing strategies that are to establish and manage the free zone of ports and its hinterland are: the establishment of a long-term vision of international logistics complexes, the improvement of the proximity to markets/customers by way of linkage of global networks, the activation of the industrial complex in hinterland, the development of the skilled labor and the labor climate, the cooperation between governmental bodies and government/provincial bodies, continuous development of logistics infrastructure and so on.

• Journal of Mechanical Science and Technology
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• v.14 no.2
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• pp.226-235
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• 2000

The performance prediction of an airfoil fan using a commerical code, STAR/CD, is verified by comparing the calculated results with measured performance data and velocity fields of an airfoil fan. The effects of inlet tip clearance on performance are investigated. The calculations overestimate the pressure rise performance by about 10-25 percent. However, the performance reduction due to tip clearance is well predicted by numerical simulations. Main source of performance decrease is not only the slip factor but also impeller efficiency. The reduction in performance is 12-16 percent for 1 percent gap of the diameter. The calculated reductions in impeller efficiency and slip factor are also linearly proportional to the gap size. The span-wise distributions of phase averaged velocity and pressure at the impeller exit are strongly influenced by the radial gap size. The radial component of velocity and the flow angle increase over the passsage as the gap increases. The slip factor decreases and the loss increases with the gap size. The high velocity of leakage jet affects the impeller inlet and passage flows. With a larger clearance, the main stream moves to the impeller hub side and high loss region extends from the shroud to the hub.

• Journal of Korea Port Economic Association
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• v.20 no.2
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• pp.19-33
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• 2004

Recognizing that the main container ports' status is gradually inclining, the Japanese government is driving forward the super hub port project. This project has three goals, unifying Japanese ports separating nationally, diminishing the port costs by 30 percents less than the current port costs of their competitors, and cutting down the lead time of processing import-export freight into 24 hours, Singaporean level. The project will work to some extent, if succeeding, but the effect is doubtful if it will be the fundamental solution of Japanese ports' crisis. I wrote this paper since I thought that this Japanese policy would serve as a good reference of Korea, which had two container ports system and its prospect was not good through the fact that the Busan ports' rank of dealing with containers fell down to the fifth in 2003.