• Title/Summary/Keyword: Overall Vibration

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Measurement and Analysis of Physical Environmental Load during Handling and Distribution of Domestic Fruits -Focused on Seongju Korean Melon

  • Jongmin Park;Donghyun Kim;Wontae Seo;Hyunmo Jung
    • KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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    • v.29 no.2
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    • pp.129-138
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    • 2023
  • The proportion of agricultural products handled through the Agricultural Products Processing Center (APC) is also steadily increasing every year, and in the case of Seongju Korean melon, a total of 10 APCs of Nonghyup and farming association corporations are in operation, and the distribution ratio is about 60% based on total production. In this study, Seongju Korean melon was selected as a target to analyze the environment load during carrying (production farm ~ APC) in the production area and the transport environment load during distribution of domestic fruits, and to analyze the environmental load for handling at APC. The vertical average vibration intensity (overall Grms of 1~250 Hz) of truck transport measured at three transport routes from Seongju Korean melon producer ~ APC, Seongju ~ Seoul and Seongju ~ Jeju was about three times larger than that in the lateral direction and 4.5 times larger than that in the longitudinal direction, respectively. The frequency of occurrence of high-amplitude events (G) in the vertical direction compared to the measuring time was deeply related to pavement conditions in the order of unpaved farm-roads, concretepaved farm-roads, and asphalt-paved main-roads, but overall Grms for the entire frequency band is believed to have a greater impact on vehicle traveling speed than road conditions. On the other hand, the difference in the size and direction of the vibration intensity measured by the forklift truck's main-body and the attachment (fork carrier) during handling at Seongju Korean melon APC was clear, and the vibration intensity of the forklift truck's main-body was largely affected by the stiffness of the fork and the mast according to the handling weight. Based on the field-data of the transport environment during domestic distribution measured through this study, it is believed that it is possible to develop a lab-based simulation protocol for appropriate packaging design.

A Study on the Efficiency of Horizontal Direction Deck-charge Blasting Method Using Electronic Detonator (전자뇌관을 이용한 수평방향 데크차지 발파공법의 효율성검토 연구)

  • Yoon, Ji-Sun;Hahn, Suk-Ju;Bae, Sang-Hun
    • Journal of the Korean Geotechnical Society
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    • v.29 no.4
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    • pp.5-11
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    • 2013
  • In close to downtown construction, the main problem is complaints caused by blasting vibration and noise. To reduce blasting vibration and noise, deck-charge blasting method using electronic detonator can be more secure because there is no cut-off problem. And in this method it is possible to blast in horizontal direction. In this study, the efficiency of horizontal direction deck-charge blasting method using electronic detonator is compared to that of the existing blasting method. And the possibility of applying the construction site is evaluated. As a result, the reduction of blasting vibration, noise and secondary breaking has been determined, as well as large-scale blasting in the vibration criterion can be regulated by the overall increase in blasting efficiency.

Preliminary Study for the Reliability Assurance on Results and Procedure of the Out-pile Mechanical Characterization Test for a Fuel Assembly; Lateral Vibration Test(I) (핵연료 집합체 노외성능시험의 절차와 결과에 대한 신뢰성확보를 위한 예비고찰; 횡방향 진동특성시험(I))

  • Lee, Kang-Hee;Yoon, Kyung-Ho;Kim, Hyung-Kyu
    • Proceedings of the KSME Conference
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    • 2007.05a
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    • pp.1854-1858
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    • 2007
  • The reliability assurance with respect to the test procedure and results of the out-pile mechanical performance test for the nuclear fuel assembly is an essential task to assure the test quality and to get a permission for fuel loading into the commercial reactor core. For the case of vibration test, which is carried out to obtain basic dynamic characteristics of the fuel assembly, proper management and appropriate calibration of instruments and devices used in the test, various efforts to minimize the possible error during the test and signal acquisition process are needed. Additionally, the deep understanding both of the theoretical assumption and simplification cation for the signal processing/modal analysis and of the functions of the devices used in the test were highly required. Finally, to verify the test result to represent the accurate natural characteristics of the structure, the proper correlation analysis between the theoretical and experimental method has to be carried out. In this study, the overall procedure and result of lateral vibration test for the fuel assembly's mechanical characterization were briefly introduced. A series of measures to assure and improve the reliability of the vibration test were discussed.

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Human Vibration Measurement for Passenger Car and Seat Characteristics Optimization (승용차에서의 인체 진동 측정 및 시트 특성 최적설계)

  • Cho, Young-Gun;Yoon, Yong-San
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.23 no.7 s.166
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    • pp.1155-1163
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    • 1999
  • This study deals with the vibration ride quality for passenger car when running on straight highway at the speed of 70km/h. Ten accelerations were measured at four positions, three axes each at the feet, hip, and head, and one axis at the back. Five seats that have different static sponge stiffness were used, and two subjects were participated. These accelerations were analyzed to produce the ride values such as component ride value and overall ride value. It was hard to see the difference of ride value by the change of sponge stiffness. However we could rank the ride quality by the total vibration exposed to passengers. From the transfer function between the hip and the foot, the fundamental mode was observed to be around 5.8Hz. Also the transfer function between the head and hip was studied. The optimal damping ratio of the seat was calculated according to the seat natural frequency with human weighting filter which makes the optimal damping ratio different from that without weighting filter.

Flexibility Effects of Components on the Dynamic Behavior of Vehicle (부품의 국부적 유연성이 차량의 동적 거동에 미치는 영향)

  • 이상범;임홍재
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.12 no.4
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    • pp.57-62
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    • 2003
  • A fundamental structural design consideration for a vehicle system is the overall vibration characteristics in bending and torsion. Vibration characteristics of such vehicle system are mainly influenced by the static and dynamic stiffness of the vehicle body structure and also by the material and physical properties of the components attached to the vehicle body structure. In this paper, modeling techniques for the vehicle components are presented and the flexibility and mass effects of the components for the vibration characteristics of the vehicle are investigated. The $1^{st}$ torsional frequency is increased by attaching windshields to the B.I.W. (body-in-white), but the $1^{st}$ bending frequency is decreased by the mass effect. And also, the natural frequencies of the vehicle are large decreased by attaching bumpers, seats, doors, trunk-lid etc. But, suspension system rarely affects the natural frequencies of the vehicle. The study shows thai the dynamic characteristics of the vehicle system can be effectively predicted in the initial design stage.

A new hybrid vibration control methodology using a combination of magnetostrictive and hard damping alloys

  • Buravalla, Vidyashankar R.;Bhattacharya, Bishakh
    • Smart Structures and Systems
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    • v.3 no.4
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    • pp.405-422
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    • 2007
  • A new hybrid damping technique for vibration reduction in flexible structures, wherein a combination of layers of hard passive damping alloys and active (smart) magnetostrictive material is used to reduce vibrations, is proposed. While most conventional vibration control treatments are based exclusively on either passive or active based systems, this technique aims to combine the advantages of these systems and simultaneously, to overcome the inherent disadvantages in the individual systems. Two types of combined damping systems are idealized and studied here, viz., the Noninteractive system and the Interactive system. Frequency domain studies are carried out to investigate their performance. Finite element simulations using previously developed smart beam elements are carried out on typical metallic and laminated composite cantilever beams treated with hybrid damping. The influence of various parameters like excitation levels, frequency (mode) and control gain on the damping performance is investigated. It is shown that the proposed system could be used effectively to dampen the structural vibration over a wide frequency range. The interaction between the active and passive damping layers is brought out by a comparative study of the combined systems. Illustrative comparisons with 'only passive' and 'only active' damping schemes are also made. The influence and the mode dependence of control gain in a hybrid system is clearly illustrated. This study also demonstrates the significance and the exploitation of strain dependency of passive damping on the overall damping of the hybrid system. Further, the influence of the depthwise location of damping layers in laminated structures is also investigated.

Vibration performance characteristics of a long-span and light-weight concrete floor under human-induced loads

  • Cao, Liang;Liu, Jiepeng;Zhou, Xuhong;Chen, Y. Frank
    • Structural Engineering and Mechanics
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    • v.65 no.3
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    • pp.349-357
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    • 2018
  • An extensive research was undertaken to study the vibration serviceability of a long-span and light-weight floor subjected to human loading experimentally and numerically. Specifically, heel-drop test was first conducted to capture the floor's natural frequencies and damping ratios, followed by jumping and running tests to obtain the acceleration responses. In addition, numerical simulations considering walking excitation were performed to further evaluate the vibration performance of a multi-panel floor under different loading cases and walking rates. The floor is found to have a high frequency (11.67 Hz) and a low damping ratio (2.32%). The comparison of the test results with the published data from the 1997 AISC Design Guide 11 indicates that the floor exhibits satisfactory vibration perceptibility overall. The study results show that the peak acceleration is affected by the walking path, walking rate, and adjacent structure. A simpler loading case may be considered in design in place of a more complex one.

Seismic vibration control of bridges with excessive isolator displacement

  • Roy, Bijan K.;Chakraborty, Subrata;Mishra, Sudib K.
    • Earthquakes and Structures
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    • v.10 no.6
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    • pp.1451-1465
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    • 2016
  • The effectiveness of base isolation (BI) systems for mitigation of seismic vibration of bridges have been extensively studied in the past. It is well established in those studies that the performance of BI system is largely dependent on the characteristics of isolator yield strength. For optimum design of such systems, normally a standard nonlinear optimization problem is formulated to minimize the maximum response of the structure, referred as Stochastic Structural Optimization (SSO). The SSO of BI system is usually performed with reference to a problem of unconstrained optimization without imposing any restriction on the maximum isolator displacement. In this regard it is important to note that the isolator displacement should not be arbitrarily large to fulfil the serviceability requirements and to avoid the possibility of pounding to the adjacent units. The present study is intended to incorporate the effect of excessive isolator displacement in optimizing BI system to control seismic vibration effect of bridges. In doing so, the necessary stochastic response of the isolated bridge needs to be optimized is obtained in the framework of statistical linearization of the related nonlinear random vibration problem. A simply supported bridge is taken up to elucidate the effect of constraint condition on optimum design and overall performance of the isolated bridge compared to that of obtained by the conventional unconstrained optimization approach.

The Effect of Automated Observation and Vibration Feedback System for Preventing VDT Syndrome of Office Workers (사무직 근로자들의 VDT 증후군 예방을 위한 자동 관찰 및 진동 피드백 시스템의 효과성 검증)

  • Ahn, Ji Yeon;Oah, Shezeen
    • Journal of the Korean Society of Safety
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    • v.34 no.3
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    • pp.75-82
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    • 2019
  • The purpose of this study was to evaluate the effectiveness of a vibration feedback system in improving two safe seating postures of office workers. In addition, the relative effectiveness of positive and negative feedback procedures was examined. Participants were four office workers. The dependent variables were the percentages of time participants spent in the safe sitting postures including shoulder, back, and overall body positions during the experimental sessions. A multiple-baseline design counterbalanced across participants was adopted. For two participants, the negative procedure was introduced first after baseline and positive procedure was introduced in the next phase. For the other two participants, the sequence of introducing the positive and negative feedback procedures was reversed. The result showed that the vibration feedback system, regardless of the type of the procedure, was effective in improving the safe sitting postures for all participants. However, the difference between the two procedures was not clearly shown. The benefits of the automated observation and vibration feedback system in workers' safety were discussed.

Test Equipment and Test Portfolio for Education of Strain and Vibration Measurements (변형률 및 진동 측정 교육을 위한 실험 장치와 실험 포트폴리오)

  • Yang, Jimin;Lee, Dooyoul
    • Journal of Practical Engineering Education
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    • v.13 no.3
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    • pp.497-505
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    • 2021
  • Test equipment for strain and vibration measurement was designed for educational purposes. Widely available and affordable materials were put into making this device. Three strain gauges placed on an iron ruler made cantilevered beam were used to measure values according to external load. An electromagnet triggered excitation and a function generator created vibration of the beam. We present three different tests conducted with this equipment regarding production of scales, measurement of resonant frequency, and calculation of the difference between excitation frequency and measured frequency. Overall, this paper presents a piece of simple yet inexpensive test equipment and its corresponding portfolio with expectations of being applied to the educational field for efficient measurement of load and vibration.