• Title/Summary/Keyword: Inertial force

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Inertia Force Comparison of 2 Stage Reciprocating Air Compressors (이단 왕복동 공기압축기 구조에 따른 관성력 비교)

  • Kim, Young-Cheol;Ahn, Kook-Young
    • The KSFM Journal of Fluid Machinery
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    • v.12 no.4
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    • pp.23-29
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    • 2009
  • For the purpose of high outlet pressure, compactness and low vibration and noise, 2 stage reciprocating air compressors can have various cylinder arrangement: opposed, in-line, and V type. This paper presents an effective method to calculate the inertia forces and to design counter weight. This method is based on the complex representation for the orbital behavior of the compressor shaft. This method helps to find the optimal balancing rate easily to reduce the inertial force or moment. This paper shows that the residual inertia forces of the single throw shafts and the residual inertia moments of the double throw shafts remain to be imbalanced.

Evaluating Method of Solitary Wave-Induced Tsunami Force Acting on an Onshore Bridge in Coastal Area (연안역의 육상 교량에 작용하는 고립파에 의한 지진해일파력의 평가법)

  • Kim, Do-Sam;Kyung, Kab-Soo;Lee, Yoon-Doo;Woo, Kyung Hwan
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.29 no.2
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    • pp.149-159
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    • 2016
  • In this study, the solitary wave-induced tsunami force acting on an onshore bridges in coastal area was numerically modelled by means of TWOPM-3D based on Navier-Stokes solver and VOF method which can track free surface effectively. The validity of numerical analysis was verified by comparing the experimental tsunami bore force acting on vertical wall and column structure. In particular, the characteristics of tsunami force with the changing tsunami intensity were surveyed through numerical experiments. The availability of 3-dimensional numerical analysis was reviewed through the comparison between the existing numerical results and design criteria for each drag force coefficient by applying Morison equation considering only drag force. As reasonable and high-precision estimation method of tsunami force, it was suggested to apply the estimation method taking drag and inertial force into consideration at the same time.

Structure and Physical Properties of Earth Crust Material in the Middle of Korean Peninsula(5) : Characteristic Measurement of Geophone using Free Impedance and Step Force Method (한반도 중부권 지각물질의 구조와 물성 연구(5) : Free impedance와 Step force법을 이용한 수진기의 특성측정)

  • 유영준;송무영
    • The Journal of Engineering Geology
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    • v.4 no.2
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    • pp.207-218
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    • 1994
  • The natural constants of moving coil type geophone can be determined by free impedance and step force method. The former method was desirable for the measurement of natural frequency($f_o$), inertial mass(m) and damping factor($h_o$), but the latter method for sensitivity(G). In particular, the value by the latter method should be corrected for the noise by the long period movement of measurement device. The results of frequency characteristics from these constants operate the accelerometer and displacement system in the boundary of natural frequency.

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Estimation Algorithm of Vehicle Roll Angle and Control Strategy of Roll Mitigation Force Distribution (차량 롤 각 추정 알고리즘 및 롤 저감력 분배 제어 전략)

  • Chung, Seunghwan;Lee, Hyeongcheol
    • Transactions of the Korean Society of Automotive Engineers
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    • v.23 no.6
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    • pp.633-641
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    • 2015
  • The ROM (roll over mitigation) system is a next-generation suspension system that can improve vehicle-driving stability and ride comfort. Currently, mass-produced safety systems, such as ESC (electronic stability control) and ECS (electronic control suspension), enable measurements of longitudinal and lateral acceleration as well as yaw rate through inertial sensor clusters, but they lack direct measurements of the roll angle. Therefore, in this paper, a roll angle estimation algorithm from ESC system sensors and tire normal force has been proposed. Furthermore, this study presents a method for roll over mitigation force distribution between the front and rear of a ROM system. Performance and reliability of the roll angle estimation and roll over mitigation force distribution were investigated through simulations. The simulation results showed that the proposed control algorithm and strategy are reliable during vehicle rollovers.

Performance of bridge structures under heavy goods vehicle impact

  • Zhao, Wuchao;Qian, Jiang;Wang, Juan
    • Computers and Concrete
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    • v.22 no.6
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    • pp.515-525
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    • 2018
  • This paper presents a numerical study on the performance of reinforced concrete (RC) bridge structures subjected to heavy goods vehicle (HGV) collision. The objectives of this study are to investigate the dynamic response and failure modes of different types of bridges under impact loading as well as to give an insight into the simplified methods for modeling bridge structures. For this purpose, detailed finite-element models of HGV and bridges are established and verified against the full-scale collision experiment and a recent traffic accident. An intensive parametric study with the consideration of vehicle weight, vehicle velocity, structural type, simplified methods for modeling bridges is conducted; then the failure mode, impact force, deformation and internal force distribution of the validated bridge models are discussed. It is observed that the structural type has a significant effect on the force-transferring mechanism, failure mode and dynamic response of bridge structures, thus it should be considered in the anti-impact design of bridge structures. The impact force of HGV is mainly determined by the impact weight, impact velocity and contact interface, rather than the simplification of the superstructure. Furthermore, to reduce the modeling and computing cost, it is suggested to utilize the simplified bridge model considering the inertial effect of the superstructure to evaluate the structural impact behavior within a reasonable precision range.

Musculoskeletal Model for Assessing Firefighters' Internal Forces and Occupational Musculoskeletal Disorders During Self-Contained Breathing Apparatus Carriage

  • Wang, Shitan;Wang, Yunyi
    • Safety and Health at Work
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    • v.13 no.3
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    • pp.315-325
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    • 2022
  • Background: Firefighters are required to carry self-contained breathing apparatus (SCBA), which increases the risk of musculoskeletal disorders. This study assessed the newly recruited firefighters' internal forces and potential musculoskeletal disorders when carrying SCBA. The effects of SCBA strap lengths were also evaluated. Methods: Kinematic parameters of twelve male subjects running in a control condition with no SCBA equipped and three varying-strapped SCBAs were measured using 3D inertial motion capture. Subsequently, motion data and predicted ground reaction force were inputted for subject-specific musculoskeletal modeling to estimate joint and muscle forces. Results: The knee was exposed to the highest internal force when carrying SCBA, followed by the rectus femoris and hip, while the shoulder had the lowest force compared to the no-SCBA condition. Our model also revealed that adjusting SCBA straps length was an efficient strategy to influence the force that occurred at the lumbar spine, hip, and knee regions. Grey relation analysis indicated that the deviation of the center of mass, step length, and knee flexion-extension angle could be used as the predictor of musculoskeletal disorders. Conclusion: The finding suggested that the training of the newly recruits focuses on the coordinated movement of muscle and joints in the lower limb. The strap lengths around 98-105 cm were also recommended. The findings are expected to provide injury interventions to enhance the occupational health and safety of the newly recruited firefighters.

Dynamic Manipulability Analysis of Limb Moving in Viscous Fluid (점성유체 속에서 움직이는 로봇팔의 동적 조작도 해석)

  • 전봉환;이지홍;이판묵
    • Proceedings of the IEEK Conference
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    • 2003.07c
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    • pp.2713-2716
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    • 2003
  • This paper presents a dynamic manipulability analysis method of the limb moving in viscous fluid. The key idea of the presented method is that the boundary of joint velocity can be converted to the velocity-dependant dynamic manipulability polytope through the coriolis, centrifugal and drag terms in dynamic equation. The velocity-dependant dynamic manipulability polytope is added to the inertial and restoring force manipulability polytope to get overall manipulability polytope of the limb moving in the fluid Each of the torque and velocity bounds arc considered in the infinite norm sense in joint space, and the drag force of a limb moving in fluid viscous is modeled as a quadratic form An analysis example with proposed analysis scheme is presented to validate the method.

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A Study on Reversal Stability of Hydraulic Excavator for Crane Work (유압 굴삭기의 크레인 작업시 전도 안정성에 관한 연구)

  • Um, Hyuk;Choi, Jong-Hwan;Kim, Seung-Soo;Yang, Soon-Yong;Lee, Jin-Gul
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.13 no.4
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    • pp.64-72
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    • 2004
  • In this paper, the dynamic stability of a hydraulic excavator using ZMP concept is considered. When a load is moved in an excavator based on automation, an excavator often loses the stability and falls over. This is because a dynamic element is not included in the moment equilibrium equation that is used in order to judge a reversal. Consequently, reversal distinction algorithm including all a static and a dynamic element along a load movement in crane work is necessary. Zero Moment Point(ZMP) is a point on the floor where the resultant moment of the gravity, the inertial force of the manipulator and the external force is zero. This study is going to interpret the reversal stability of the excavator to which is applied ZMP concept through simulation.

Analysis of electron emission mechanism in surface conduction electron emission displays (표면전도 전자방출 표시장치의 전자방출 구조해석)

  • 김영삼;김영권;오현주;조대근;길도현;김대일;강준길;강승언;최은하
    • Journal of the Korean Vacuum Society
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    • v.8 no.4A
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    • pp.410-416
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    • 1999
  • It is confirmed that the cause of anode current in SEDs (surface conduction electron emission displays) is the inertial force of electron emitted from the cathode surface in the calculation of electron trajectory. In the fissure of sub-micron, most of electrons emitted from the area of the cathode edge flow into the coplanar anode, while some electrons are emitted into the display surface by the current ratio of $10^{-3}$. The later electrons are forced to fly into the display surface by the centrifugal force due to the curved electric field between top side surfaces near the fissure.

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A Study on the Compensation Algorithm for Tension of Belt which is used as the Force Transfer Media Induction Motor (유도 전동기의 동력전달매체로 사용되는 벨트의 장력 보상 알고리즘에 관한 연구)

  • 김승환;임무생
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.48 no.9
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    • pp.1126-1130
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    • 1999
  • This paper persents an algorithm compensating for the change of tension acting on a belt which is used as a force transfer media of the induction motor that drives a washing machine. The induction motor adopted in a washing machine is operated not only for the power-transmission device, but also for the detection of clothes load. The load of clothes is determined by the duration of inertial rotation which is occurred by the induction motor during a specific time. The tension of belt also affects the determination of clothes load as another load and this change of the tension is a significant disturbance for accurate determination. This paper mentions the algorithm compensating for the amount of change in tension and the application of the algotithm proved to be effectively increasing the washing performance and reducing the noise and the vibration.

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