• Title/Summary/Keyword: cushion

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A Deformation Model of a Bag-Finger Skirt and the Motion Response of an ACV in Waves (Bag-Finger형 스커트의 변형모델과 규칙파중 공기부양선의 운동해석)

  • G.J. Lee;K.P. Rhee
    • Journal of the Society of Naval Architects of Korea
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    • v.29 no.2
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    • pp.48-59
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    • 1992

  • In this paper, the effects of a skirt deformation on the responses of an Air Cushion Vehicle in waves are investigated. The air in the bag and in the plenum chamber is assumed to be compressible and to have a uniform instantaneous pressure distribution in each volume. The free surface deformation is determined in the framework of linear potential theory by replacing the cushion pressure with the pressure patch moving uniformly with an oscillating strength. And the bag-finger skirt is assumed to be deformed due to the pressure disturbance while its surface area remained constant. The restoring force and moment due to the deformation of bag-finger skirt from the equilibrium shape is included in the equations of hearse and pitch motions. The numerical results of motion responses due to various ratios of the bag and cushion pressure or bag-to-finger depth ratios are shown.

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Nonlinear finite element modeling of the self-centering steel moment connection with cushion flexural damper

  • Ali Nazeri;Reza Vahdani;Mohammad Ali Kafi
    • Structural Engineering and Mechanics
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    • v.87 no.2
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    • pp.151-164
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    • 2023

  • The latest earthquake's costly repairs and economic disruption were brought on by excessive residual drift. Self-centering systems are one of the most efficient ways in the current generation of seismic resistance system to get rid of and reduce residual drift. The mechanics and behavior of the self-centering system in response to seismic forces were impacted by a number of important factors. The amount of post-tensioning (PT) force, which is often employed for the standing posture after an earthquake, is the first important component. The energy dissipater element is another one that has a significant impact on how the self-centering system behaves. Using the damper as a replaceable and affordable tool and fuse in self-centering frames has been recommended to boost energy absorption and dampening of structural systems during earthquakes. In this research, the self-centering steel moment frame connections are equipped with cushion flexural dampers (CFDs) as an energy dissipator system to increase energy absorption, post-yielding stiffness, and ease replacement after an earthquake. Also, it has been carefully considered how to reduce permanent deformations in the self-centering steel moment frames exposed to seismic loads while maintaining adequate stiffness, strength, and ductility. After confirming the FE model's findings with an earlier experimental PT connection, the behavior of the self-centering connection using CFD has been surveyed in this study. The FE modeling takes into account strands preloading as well as geometric and material nonlinearities. In addition to contact and sliding phenomena, gap opening and closing actions are included in the models. According to the findings, self-centering moment-resisting frames (SF-MRF) combined with CFD enhance post-yielding stiffness and energy absorption with the least amount of permeant deformation in a certain CFD thickness. The obtained findings demonstrate that the effective energy dissipation ratio (β), is increased to 0.25% while also lowering the residual drift to less than 0.5%. Also, this enhancement in the self-centering connection with CFD's seismic performance was attained with a respectable moment capacity to beam plastic moment capacity ratio.

  • https://doi.org/10.12989/sem.2023.87.2.151 인용

Body Stereotatic Radiosurgery Procedure of Base on Image Guided (Image Guided에 기초한 Body Stereotatic Radiosurgery의 과정)

  • Choi Yun-Kyeung;Lee Doo-Hyun;Cho Jung-Keun;Kim Jong-Won;Youm Doo-Seok;Kim Tae-Yoon;Choi Gye-Sook
    • The Journal of Korean Society for Radiation Therapy
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    • v.17 no.2
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    • pp.95-103
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    • 2005

  • Purpose : In the radiosurgery, to obtain CT image to find more accurate tumor position during respiration, and using them, to increase the accuracy of radiation treatment by applying image guided. Materials and Methods : Using the self-made vacuum cushion for the body SRS, CT images were obtained three for each patient during respiration (shallow, inhalation, exhalation). They were transformed to the RTP computer and then were fused. Global GTVs were delineated on the fused images and more appropriated treatment planning was established. Results : We can find the tumor position is moving toward cranio-caudal with max 10 mm margin and volume is transformed. As a result from the comparision of DVH (pre & post radio surgery), we observed about 100% dose to tumor. Conclusion : BSRS was skeptical due to the tumor movement during respiration. More accurate by the combination of the development of immobilization devices and BSRS based on Image Guide, it will be applied to more cases for BSRS.

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A Study on the Development of Lightweight Seat Cushion Extension Module (경량형 시트 쿠션 익스텐션 모듈 개발에 관한 연구)

  • Jang, Hanseul;Choi, Seongkyu;Park, Sang-Chul;Lim, Heon-pil;Oh, Eu-Ddeum
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.17 no.8
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    • pp.200-207
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    • 2016

  • The automotive seat is an important component that moves in sync with the driver and is actively being developed with various new functions. The aim of this work is to develop a lightweight seat cushion extension module using a lightweight material. To this end, a structural strength analysis, vertical strength test, and durability test were conducted. In the structural analysis, the maximum value of deformation under vertical load was 4.98 mm at the front of the upper panel. The maximum stress was approximately 105 MPa, which occurred at the point of contact between the upper and lower panels of the module. The vertical strength test showed a maximum vertical deformation of 5.31 mm under a vertical load, which differed from the analysis results by approximately 6.45%. The structural safety of the product was verified by the fact that it showed no harmful deformation or damage during operation after the vertical strength test and a durability test for 20,000 cycles. Furthermore, the use of engineering plastics made it possible to reduce the weight by approximately 30% compared to existing products. The lack of damage after tests verified the passenger safety, strength, and rigidity of the product. The results are expected to be applied for improving environmental and fuel efficiency regulations and preventing accidents due to driver fatigue. The applications of this module could be expanded various types of vehicles, as well as other industries in which eco-friendly and lightweight materials are used.

  • https://doi.org/10.5762/KAIS.2016.17.8.200 인용 PDF KSCI