• Title/Summary/Keyword: 좌석 진동

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Subjective Estimation of Comfort of a Seated Human Body due to the Vertical Vibrations (인체진동의 주관적평가에 관한 연구)

  • ;Griffin, Michael J.
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 1998.04a
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    • pp.69-74
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    • 1998
  • 차량에서 인체가 노출되는 진동환경으로서 좌석과 바닥에서의 진동사이에 위상차가 존재하는 경우에 대한 인체의 반응을 주관평가 실험을 통해 분석하였다. 인체가 진동에 민감하게 반응할 뿐만 아니라 인체와 좌석으로 구성되는 진동시스템의 공진주파수와 관련된 2.5, 3.15, 4, 5, 6.3 Hz의 주파수에서, 진동의 크기를 각각 0.25, 0.4, 0.63, 1.0, 1.6m/s$^{2}$로 변화시켜 가며 위상차가 인체의 안락성에 어떻게 영향을 미치는 지를 분석하였다. 두 진동간의 위상차는 진동량이 적을수록, 또 주파수가 낮을수록 인체의 안락성에 악영향을 미쳤다. 진동의 진폭이 0.25m/s$^{2}$ 일 때 위상차가 180.deg.인 경우의 불편함은 0.deg.인 경우보다 2.5배 정도 큰 것으로 나타났다. 특히 현가장치가 장착된 의자의 경우에는 좌석과 바닥진동의 위상차이가 안락성에 미치는 영향을 정량적으로 파악하여 인체-좌석 시스템의 공진주파수를 선정해야 함을 알 수 있다.

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Simulation of Dynamic Characteristics of Agricultural Tractor (III) - Effect of Design Parameters on Seat Vibrations - (농용 트랙터의 동특성 시뮬레이션 (III) - 주요 설계 변수가 좌석 진동에 미치는 영향 -)

  • 박홍제;김경욱
    • Journal of Biosystems Engineering
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    • v.24 no.3
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    • pp.183-194
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    • 1999
  • Using the dynamic model and simulation program TDA developed in the previous paper, effects of design parameters of an agricultural tractor-trailer system on its vertical seat vibrations were investigated. The tractor-trailer system was excited by traversing over a half-sine bump. The excitation frequencies were determined by traveling velocity of the tractor and a half-sine bump selected appropriately. TDA predicted the autospectra of the vertical seat accelerations with different values of design parameters and compared them to analyze their effects. The design parameters included positions of engine, cab, and seat mountings as well as their dynamic properties. The results of this study suggested guidelines with which an improved structure of tractor may be developed in the early stage of design for a better ride quality.

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Tools to Understand Interior Noise due to Road Excitation in Cars (노면 가진에 의한 실내 소음 해석 방법)

  • Taewon Kang;Sang-Gyu Lim
    • Journal of KSNVE
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    • v.8 no.6
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    • pp.1158-1165
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    • 1998
  • Low frequency interior noise in cars is mainly due to structure-borne excitations which are related with road excitation and component vibrations such as suspension and engine mounts. In order to analyze the annoying interior noise. a technique (Transfer Path Analysis) is introduced to find a noise source and the path of that noise. In this study, TPA is reviewed theoretically and applied to investigate the case when the low frequency interior noise at front seat due to road excitations needs to be optimized. The subjective and objective appraisal was performed under the conditions that a testing vehicle traveled on asphalt at 30 km/h. so that the low frequency to be eliminated was detected. The related vibration and noise data for TPA were measured on running and static vehicle. The results reveal that the noise contribution along the z-direction of trailing arm is prominent to low frequency interior noise.

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A Study on the Modeling of a Passenger Car Cavity with consideration of Trunk Coupling Effect (트렁크 연성 효과를 고려한 차실 음향 모델링에 관한 연구)

  • 강상욱;이장무;김석현
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 1994.10a
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    • pp.300-305
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    • 1994
  • 차실 음향 공동의 특성을 유한요소법에 의해 해석하고자 할 때, 과거에는 차실 음향공동과 트렁크 음향공동과의 상호연성을 고려하지 않고, 두 공동의 경계면을 강체 경계조건으로 생각하여 해석 대상 모델을 차실 음향 공동만으로 국한시켰다. 이러한 해석 방법을 통해서는, 차실과 트렁크 공동이 완전히 밀폐되어 있지 않고 단지 뒷좌석에 의해 두 공동이 구별되어지는 차종에 대해서는 실험과 근접하는 유한요소해석 결과를 얻을 수 없다. 그러므로 차실 공동과 트렁크 공동의 경계면을 가상의 탄성벽 경계조건으로 생각하여 그 탄성벽을 통한 두 공동의 상호 연성을 고려하는 유한요소 모델을 구현하여야 한다. 실제로 트렁크가 차실에 미치는 연성효과를 고려하여 유한요소해석을 수행할 경우 차실의 고유진동수와 고유모드에 미치는 영향이 상당히 큰 것을 확인할 수 있었다. 이하 본 내용에서는 차실과 트렁크 공동, 그 사이의 탄성벽을 이론적으로 해석 가능한 1차원으로 모델링하여 실험 결과와 근접하는 3차원 유한요소 모델링 기법을 제시한다.

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Comfort Analysis of Mono-ski with Hydraulic Absorber (모노스키 유압 완충장치 특성에 따른 탑승 안락감 평가)

  • Cho, Hyeon-Seok;Park, Jin-Kook;Kim, Gyoo-Seok;Mun, Mu-Sung;Kim, Chang-Boo
    • Transactions of the KSME C: Technology and Education
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    • v.3 no.2
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    • pp.131-140
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    • 2015
  • The mono-ski for the paraplegia designed to skiing is formed as seat bucket on the sled. The impact force transferred by snow surface during skiing is absorbed by the leg joints of normal human, but it is transferred to the human body on the seat when using mono-ski. Most of commercially available mono-ski have absorbing device and link mechanism between seat and ski mount in order to complement it. In this study we developed the comfort evaluation model that could provide skiing simulation of mono-ski with hydraulic damper and analyzed vibrational acceleration occurred during skiing uneven surface. The evaluation method used in this study is the international standard BS6841. We evaluated comfort performance of mono-ski in accordance with nozzle adjustment of hydraulic damper.

Vibration Reduction Devices for Korean Utility Helicopter (한국형기동헬기 진동저감장치)

  • Jung, Se-Un;Kwak, Dong-Il;Kim, Se-Hee;Choi, Jong-Ho;Shim, Dai-Sung
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.41 no.12
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    • pp.987-993
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    • 2013
  • Korean Utility Helicopter(KUH) is the first korean-developed helicopter. Its first flight was performed in March 2010 and then its development was completed successfully by June 2012. During flight test phase, KUH faced various vibration problems and appropriate vibration-reduction devices were designed and applied to solve the problems. The vibration-reduction devices were applied to main rotor blades, main gear box(MGB) supporting structure, cockpit, cabin and pilot seats to reduce rotor-induced 4/rev vibration. Also, dome-fairing was introduced in order to reduce the tail-shake vibration. This paper shows design technique and flight test results for vibration-reduction devices that have been incorporated into KUH.

Investigation of Transmission Characteristics of Tractor Seat Vibrations Using Vibration Path Analysis Method (VPA를 이용한 트랙터 좌석 진동의 전달 특성 구명)

  • 이주완;김경욱
    • Journal of Biosystems Engineering
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    • v.26 no.3
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    • pp.237-244
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    • 2001
  • This work was intended to investigate the effect of vibration transmission paths on the ride vibration of tractor during the rotavating and transporting operations by applying the vibration path analysis method. Accelerations at the cab mounts were measured during the rotavating and transporting operations. Ride vibrations at the sear were than calculated using the measured accelerations at the cab mounts, and the frequency response functions and inertances between the seat and cab mounts, which were derived experimentally by the impact hammer test in static condition. The human sensitivity to vibration frequency was also taken into consideration for the calculation of ride vibrations at the 1/3 octave center frequencies in the frequency domain. Vibrations transmitted through rear cab mounts affected more significantly the ride vibration of tractor. The peak accelerations at the seat occurred at the frequencies of the engine and crank speed, and the frequency induced by tire lugs on the road transportation. It was found that the rear cab mounts should be improved in order to reduce the ride vibrations more effectively.

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Development of 1-axis Exciter for a Seat Vibration Test of Agricultural Tractors(I) - Design of PID Controller for Position Control of 1-axis Exciter - (농용트랙터용 운전자 좌석 진동 시험을 위한 1축 가진 시험기 개발(I) - 1축 가진 시험기 위치 제어를 위한 PID 제어기 설계 -)

  • Yu, Ji-Hoon;Choi, Young-Kyun;Lee, Kyu-Cheol;Kim, Young-Joo;Ryu, Young-Sun;Ryuh, Kwan-Hee
    • Journal of Biosystems Engineering
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    • v.34 no.5
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    • pp.305-314
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    • 2009
  • The purpose of this paper was to design an effective control system of 1-axis exciter for a seat vibration test of agricultural tractors using MATLAB simulation. The developed simulation model was composed with a hydraulic pump, a hydraulic servo valve, a hydraulic cylinder and load system. Also it was verified by comparing the simulation results with experimental results of actual control system in order to optimize the control performance. And in order to improve its control performance, the designed PID controller in this research was tuned using Ziegler-Nichols 2nd law and zero's moving method of PID controller's transfer function. As the result of these research, the developed position control system was able to control the system's position accurately within 5% errors.

Active Sound Control Approach Using Virtual Microphones for Formation of Quiet Zones at a Chair (좌석의 정음공간 형성을 위한 가상마이크로폰 기반 능동음향제어 기법 연구)

  • Ryu, Seokhoon;Kim, Jeakwan;Lee, Young-Sup
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.25 no.9
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    • pp.628-636
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    • 2015
  • In this study, theoretical and experimental analyses were performed for creating and moving the zone of quiet(ZoQ) to the ear location of a sitter by using active sound control technique. As the ZoQ is actively created at the location of the error microphone basically with an active sound control system using an algorithm such as the filtered-x least mean square(FxLMS), the virtual microphone control(VMC) method was considered to move the location of the ZoQ to around the sitter`s ear. A chair system with microphones and loudspeakers on both sides was manufactured for the experiment and thus an active headrest against the swept narrowband noise as the primary noise was implemented with a real-time controller in which the VMC algorithm was embedded. After the control experiment with and without the VMC method, the location variation of the ZoQ by analyzing the error signals measured by the error and the virtual microphones. Therefore, it is observed that the FxLMS with the VMC technique can provide the re-location of the ZoQ from the error microphone location to the virtual microphone location. Also it is found that the amount of the attenuation difference between the two locations was small.