• Title/Summary/Keyword: stiffness requirements

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A Study on the Optical Bench for LEO Earth Observation Satellite (저궤도 지구관측위성의 광학탑재체 지지구조물 설계 연구)

  • Kim, Kyung-Won;Kim, Jin-Hee;Rhee, Ju-Hun;Jin, Ik-Min;Kim, Jong-Wo
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2005.05a
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    • pp.805-808
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    • 2005
  • This paper is a study on an optical bench satisfying stiffness and thermal pointing error requirements for LEO earth observation satellite. According to shape and stiffness requirements, optical bench type 1 is designed. Because type 1 does not satisfy the thermal pointing error requirement, an optical bench type 2 is suggested. Although the type 2 has better results than type 1, it still does not meet the thermal pointing error requirement. Using the results of optical bench type 1&2, the optical bench type 3 is finally designed, which satisfies both the stiffness and thermal pointing error requirements.

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Development of Drift Design Methods with Weight Modification Factors (중량 수정계수를 고려한 변위조절설계법 개발)

  • 서지현;박효선
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2003.10a
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    • pp.161-168
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    • 2003
  • In the drift design of high-rise buildings, once the geometry and dimensions of a structure are predetermined, engineer's remaining work is determination of the member size to satisfy the strength and the stiffness requirements. For the case of highrise buildings, designs are determined by the stiffness requirements at the final stage of structural design. Thus, engineers try to find a minimum weight design with maximum lateral stiffness. However, there is no guideline for engineers on the required weight of structures per unit area to satisfy the stiffness requirements. In this study, drift design method considering weight modification factors are presented and applied to a 20-story structure. The proposed drift design method considering weight modification factors may give the guideline for engineers on the amount of structural weight to attain target displacement.

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Comparative Study of Design Codes on the Transverse Steel Amount of Circular Reinfored Concrete Columns (철근콘크리트 원형단면교각의 횡방향철근량에 관한 설계비교)

  • 배성용;곽동일;김희덕
    • Journal of Ocean Engineering and Technology
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    • v.15 no.1
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    • pp.98-103
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    • 2001
  • This paper is conducted to compare the seismic design standard of a bridge column such as the Korean Bridge Design Standard(KBDS), EC 8, NZS 3101 and ATC 32. The KBDS adopted the seismic design requirements in 1992. The earthquake magnitude in Korea is compared with those in the west coast of the USA. It may be said that the current seismic design requirements of the KBDS provides design results, that are too conservative especially for transverse reinforcement details and amounts in reinforced concrete columns. This fact usually creates construction problems in concrete casting, due to congestion of transverse reinforcement. Furthermore, the effective stiffness; $I_{eff}$ depends on both the axial load P/$A_gF_{ck}$ and the longitudinal reinforcement ratio $A_{st}/A_g, so it is the conservative to use the effective stiffness I$_{eff}$ than the gross section stiffness Ig. Seismic design for the transverse reinforcement content of the concrete column was analyzed and considered to have an extreme-fiber compression strain, response modification factor, axial load and effective stiffness etc.c.

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A Study on the Dynamic Characteristics of the Composite Boring Bar (복합재료 보링바의 동적 특성에 관한 연구)

  • 황희윤;김진국;이대길
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2003.04a
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    • pp.206-210
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    • 2003
  • Machining of deep holes with conventional boring bars frequently induce chatter vibration because of their low dynamic stiffness which is defined as the product of static stiffness and damping of conventional boring bar materials. In addition, the specific stiffness ($E/{\rho}g$) of boring bars is more important than the static stiffness to increase the fundamental natural frequency of boring bars in high speed machining. Therefore, boring bar materials should have high static stiffness and high damping as well as high specific stiffness. The best way to meet requirements is to employ fiber reinforced composite materials for high speed boring bars because composite materials have high static stiffness, high damping and high specific stiffness compared to conventional boring bar materials. In this study, the dynamic characteristics of carbon fiber epoxy composite boring bars were investigated. From the metal cutting test, it was found that the chatter was not initiated up to the ratio of length to diameter of 10.7 at the rotating speed of 2,500 rpm.

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comparative Study on confinement Steel Amount of RC Column Bent (철근콘크리트 교각 심부구속철근량의 비교연구)

  • 이재훈
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • 1999.04a
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    • pp.239-246
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    • 1999
  • recently there have been many destructive seismic events in Kobe Japan in 1995 and in Northridge California USA in 1994. etc. The Korean Bridge Design Standard Specifications adopted the seismic design requirements in 1992. Comparing the earthquake magnitude in Korea with those in the west coast of the USA it may be said that the current seismic design requirements of the Korean Bridge Design Standard Specifications provides too conservation design results especially for transverse reinforcement details and amount in reinforced concrete columns. This fact usually makes construction problems in concrete casting due to transverse reinforcement congestion. And the effective stiffness Ieff depends on the axial load P(Ag{{{{ {f }_{ck } }}) and the longitudinal reinforcement ratio Ast/Ag and it is conservative to use the effective stiffness Ieff than the gross section moment Ig. Seismic design for transverse reinforcement content of concrete column is considered of extreme-fiber compression strain R-factor axial load and stiffness etc.

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A Study on the Development of High Stiffness Body for Suspension Performance (서스펜션 성능 확보를 위한 고강성 차페 개발 프로세스 연구)

  • Kim, Ki-Chang;Kim, Chan-Mook
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.15 no.7 s.100
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    • pp.799-805
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    • 2005
  • This paper describes the development process of high stiffness body for ride and handling performance. High stiffness and light weight vehicle is a major target in the refinement of Passenger cars to meet customers' contradictable requirements between ride and handling performance and fuel economy This paper describes the analysis approach process for high stiffness body through the data level of body stiffness. According to the frequency band. we can suggest the design guideline about lg cornering static stiffness, torsional and lateral stiffness, body attachment stiffness. The ride and handling characteristic of a vehicle Is significantly affected by vibration transferred to the body through the chassis mounting points from front and rear suspension. It is known that body attachment stiffness is an important factor of ride and handling performance improvement. And high stiffness helps to improve the flexibility of bushing rate tuning between handling and road noise. It makes possible to design the good handling performance vehicle and save vehicles to be used in tests by using mother car at initial design stage. These improvements can lead to shortening the time needed to develop better vehicles.

A Study on the Development of High Stiffness Body for Suspension Performance (서스펜션 성능 확보를 위한 고강성 차체 개발 프로세스 연구)

  • Kim, Ki-Chang;Kim, Chan-Mook
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2004.11a
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    • pp.358-361
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    • 2004
  • This paper describes the development process of high stiffness body for ride and handling performance. High stiffness and light weight vehicle is a major target in the refinement of passenger cars to meet customers' contradictable requirements between ride and handling performance and fuel economy. This paper describes the analysis approach process for high stiffness body through the data level of body stiffness. According to the frequency band, we can suggest the design guideline about Is cornering static stiffness, torsional and lateral stiffness, body attachment stiffness. The ride and handling characteristic of a vehicle is significantly affected by vibration transferred to the body through the chassis mounting points from front and rear suspension. It is known that body attachment stiffness is an important factor of ride and handling performance improvement. And high stiffness helps to improve the flexibility of bushing rate tuning between Handling and road noise. It makes it possible to design the good handling performance vehicle at initial design stage and save vehicles to be used in tests by using mother car at initial design stage. These improvements can lead to shortening the time needed to develop better vehicles.

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Optimal Redundant Actuation of Parallel Manipulators with High Operational Stiffness (고강성 병렬형 로봇의 최적 여유 구동)

  • Kim, Sung-Bok
    • Journal of Institute of Control, Robotics and Systems
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    • v.6 no.2
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    • pp.181-189
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    • 2000
  • This paper presents the optimal redundant actuation of parallel manipulators for complicated robotic applications such as cutting grinding drilling and digging that require a high degree of operational stiffness as well as the balance between force applicability and dexterity. First by taking into account the distribution(number and location) of active joints the statics and the operational stiffness of a redundant parallel manipulator are formulated and the effects of actuation redundancy are analyzed, Second for given task requirements including joint torque limit task force maximum allowable disturbance and maximum allowable deflection the task execution conditions of a redundant parallel manipulator are derived and the efficient testing formulas are provided. Third to achieve high operational stiffness while maintaining moderate dexterity the redundant actuation of a parallel manipulator is optimized which determines the optimal distribution of active joints and the optimal internal joint torque, Finally the simulation results for the optimal redundant actuation of a planar parallel manipulator are given.

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A Study on the Analysis on Running Safety of Railway Vehicle According to The Change of Suspension Stiffness (현가장치 강성변화에 따른 주행안전성 해석에 관한 연구)

  • Hyun, Seok;Eom, Beom-Gyu;Lee, Hi-Sung
    • Proceedings of the KSR Conference
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    • 2008.11b
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    • pp.1622-1627
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    • 2008
  • A suspension is a core part, determining running stability and riding quality of vehicles and its stiffness is essential parameters in the process of vehicle designing. Suspension stiffness shall be adjusted to meet requirements of running stability and curve running performance, as adding stiffness to primary suspension for running stability in high-speed running results running performance degradation in curved track. The purpose of the report lies in utilization of usable data for optimization of suspension via analyzing running performance through changing stiffness of railway vehicle suspension.

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A Study on Seismic Performance of Spiral Prer (나선철근교각의 내진성능에 관한 연구)

  • 배성용;김광수;이형준;이재훈
    • Proceedings of the Korea Concrete Institute Conference
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    • 2000.04a
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    • pp.363-368
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    • 2000
  • The Korean Bridge Design Standard Specifications adopted the seismic design requirements in 1992. However, The current seismic design requirements for bridges are based on the USA seismic codes for sever earthquake. This provides the basic factors that affects the performance of spiral reinforced concrete piers for seismic loading, and The specimen tests are performed based on load-displacement, effective stiffness and displacement ductility, etc. The quasi-static test was adopted in order to investigate seismic performance of the spiral reinforced concrete pier specimens which had different transverse steel amount, spacing and longitudinal steel ratio under different axial load levels. This study is concluded that seismic design for transverse reinforcement content of spiral reinforced concrete column has influenced on axial load and effective stiffness etc.

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