• 소음진동
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• 제7권1호
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• pp.143-152
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• 1997

This paper introduces experimental results of the ride qulaity characteristics of automotive seats fixed on the vibration table that is noving simultaneously to the three-axis in a similar way to the real running condition. Vibration experiment was carried out for five different automotive seats and four Korean individuals. The assessment of the ride quality characteristics for each seat and indiviual was made not only from the analysis of vibration measurements but also from the evaluation of weighied vibration signals, which were obtained using the frequency weighting function and the multiplication factor dependent on the position and axis of vibration exposure to wehole-body. The usefulness of those assessment results in analysis of the ride quality of seats is discussed and their limitation is also pointed out in this paper.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 춘계학술대회논문집
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• pp.1105-1110
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• 2001

본 논문은 머리진동 측정용 바이트 바의 동적 특성에 관한 연구이다. 머리진동의 관심주파수 영역은 0.5Hz~30Hz 범위의 주파수이며 기구학적 이론들을 이용하여 측정된 선형 가속도로부터 머리의 각각속도를 계산하는 과정을 소계한다. 본 논문에서는 9개의 선형가속도를 이용하여 각각속도를 구하는 방법에 대한 검증뿐 아니라 나아가 센서의 측정점의 Offset 영향을 고려한 이론식을 제시한다.

• The Journal of Korean Physical Therapy
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• 제32권3호
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• pp.137-145
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• 2020

Purpose: The purpose of this study is to examine the effect of various bridge exercises on walking ability. Method: The subjects were 30 stroke patients. They were divided into a bridge exercise group on a stable support surface (Group I), a bridge exercise group on an unstable support surface (Group II), and a bridge exercise group combined with whole body vibrations (Group III). 10 subjects were randomly assigned into each group. The subjects of this study had 30 minutes of nervous system physical therapy including gait training and strength training. In addition, each group underwent a 30 minutes session five times a week for eight weeks. Before intervention, LUKOtronic was used to measure step width and step length, time was measured with a 10 m walking test, and time and number of steps were measured with the figure 8 walking test. After the intervention, remeasured and analysis was performed for each group. Results: As a result of comparing and analyzing the change of walking ability between groups, there was a statistically significant difference. As a result of the post hoc analysis according to the change of walking ability among groups, the change of walking ability was larger in Group III than in Group I and Group II. Conclusion: Based on these results, it is confirmed that the bridge exercise combined with whole body vibration was more effective for walking ability. Based on these findings, this study proposes an effective program for elite athletes as well as stroke patients.

• The Journal of Korean Physical Therapy
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• 제30권4호
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• pp.135-140
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• 2018

Purpose: This study aimed to determine the appropriate stimulus strength that could result in a positive effect on the ankle joint spasticity when patients with chronic stroke performed whole body vibration (WBV) exercise. Methods: Among 72 patients who were diagnosed with stroke at least 6 months ago, those able to perform a half squat pose with ambulation issues due to ankle joint spasticity (modified Ashworth scale, $MAS{\geq}2$) were included for analysis. Individuals participated in four different frequencies of vertical WBV exercise; 0 Hz, 10 Hz, 20 Hz, and 30 Hz. Vibration amplitude was 3-4 mm and 5 minutes WBV exercise was performed at each frequency, followed by a measurement after 2-minute rest. We assigned 18 individuals to each frequency and asked them to participate in the WBV exercise once every 3 weeks. The level of spasticity was evaluated by visual analogue scale (VAS) for self-assessment. The myoton PRO was utilized to objectively evaluate the level of spasticity and check the muscle tone and stiffness. Results: Participants showed 0 Hz VAS was a significant difference between 20 Hz application conditions (p<0.05). Muscle tone was significantly different at 0 Hz between 20 Hz, and 30 Hz (p<0.05), significantly difference at 10 Hz between 30 Hz (p<0.05). Muscle stiffness significantly difference at 0 Hz between 20 Hz, and 30 Hz (p<0.05), significantly difference at 10 Hz between 20 Hz, and 30 Hz (p<0.05). Conclusion: Findings of this study show that the frequency of more than 20 Hz was effective in improving the ambulatory ability in patients with chronic stroke. Currently, the effective WBV protocol is limited. Hence, this study was designed to suggest an effective WBV protocol to improve neuromodulation ability for chronic stroke patients.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2009년도 추계학술대회 논문집
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• pp.623-624
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• 2009

• Safety and Health at Work
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• 제4권3호
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• pp.149-155
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• 2013

Background: Stochastic resonance whole-body vibration training (SR-WBV) was tested to reduce work-related musculoskeletal complaints. Methods: Participants were 54 white-collar employees of a Swiss organization. The controlled crossover design comprised two groups each given 4 weeks of exercise and no training during a second 4-week period. Outcome was daily musculoskeletal well-being, musculoskeletal pain, and surefootedness. In addition, participants performed a behavioral test on body balance prior to when SR-WBV started and after 4 weeks of SR-WBV. Results: Across the 4-week training period, musculoskeletal well-being and surefootedness were significantly increased (p < 0.05), whereas musculoskeletal pain was significantly reduced only in those who reported low back pain during the last 4 weeks prior to the study (p < 0.05). Body balance was significantly increased by SR-WBV (p < 0.05). Conclusion: SR-WBV seems to be an efficient option in primary prevention of musculoskeletal complaints and falls at work.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 춘계학술대회논문집
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• pp.546-550
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• 2008

Impulsive excitation on vehicles produces shock-type vibration on the seat, usually which has major frequencies and damping ratios dependent on the characteristics of the suspension, the tire, the seat cushion and so on. The response of single degree of freedom model to a half-sine force input was considered as simple shock-type vibration signal. The quasi-apparent-mass for fifteen subjects was obtained with the shock-type vibration generated on the rigid seat, so its nonlinearity was found over 6.3 Hz according to the difference of magnitude of the shocks.

• 대한인간공학회지
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• 제32권4호
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• pp.309-319
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• 2013

Objective: The aim of this study is to review and summarize human vibration measurement process, and necessity and methods of frequency weightings for human vibration. Background: Prolonged human exposure to hand-arm vibration and whole-body vibration can result in a range of adverse conditions and the development of occupational diseases such as vibration white finger. For preventing these adverse effects, it is important to correctly apply human vibration measurement process. Method: This manuscript was based on the review and summary of mechanical and human vibration relevant texts, academic papers, materials obtained through web surfing. Results: This manuscript summarizes human vibration measurement process described in ISO standards and relevant texts. The sensitivity of the human body to mechanical vibration is known to be dependent on both the frequency and direction of vibration. To take this into account, varying frequency weighting functions have been developed, and RMS frequency-weighted accelerations are used as the most important quantity to evaluate the effects of vibration on health. ISO provided nine frequency weighting functions in the form of curves and tables. Researches on frequency weightings are focused on development and validation of new frequency weightings to truly reflect the relationship between vibration exposure and its adverse effects. Application: This would be useful information for systematically applying human vibration measurement and analysis process, and for selecting appropriate frequency weighting functions.

• 융합정보논문지
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• 제9권10호
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• pp.234-243
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• 2019

본 연구는 호흡저항이 병행된 전신진동자극 훈련이 뇌졸중환자의 호흡기능 및 균형기능에 미치는 영향을 알아보기 위하여 실시하였다. 만성 뇌졸중환자 17명을 호흡저항이 병행된 전신진동자극 훈련을 적용한 실험군(n=8)과 일반 진동운동프로그램을 적용한 대조군(n=9)으로 무작위 배정하였다. 중재는 30분간 1일 1회 주 3회, 4주간 실시하였다. 중재 전후 폐활량과 호흡근력 그리고 동적/정적 균형능력을 측정하여 비교하였다. 실험군에서 정 동적 균형능력, 폐활량과 호흡근력의 전 후 비교 결과 유의한 향상을 보였다(p<.05). 그리고 실험군과 대조군을 비교하였을 때 동적 균형능력, 폐활량과 호흡근력의 결과값에서 유의한 차이를 보였다(p<.05).실험군의 폐활량과 호흡근력 또한 실험전후 유의한 향상을 보였으며, 대조군에 비해 유의한 변화량의 차이를 나타내었다(p<.05). 본 연구결과를 통하여 호흡저항이 병행된 전신진동자극훈련은 뇌졸중환자의 호흡기능 및 균형능력 향상 프로그램으로 유익할 것으로 사료된다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.409-414
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• 2007

Nowadays, with the advancement of computational mechanics, and vehicle dynamics simulation linked up with virtual testing laboratory(VTL) and virtual proving ground(VPG) technologies has become a useful method for analyzing numerous driving performances and diverse noise/vibration characteristics. In this paper, the analytical vehicle model based on multi-body dynamics theory was developed to investigate the vibration characteristics according to various road conditions. For the purpose, the whole vehicle parameters, each vehicle's part parameter, and part connecting elements such as spring, damper, and bush were measured by an experiment. Also, the vehicle dynamics model, which includes the front suspension, rear suspension, steering, front wheel, rear wheel, and body subsystems has been constructed for computer simulation. With the developed vehicle dynamics model, three forces and three moments measured at each wheel center were applied to evaluate and analyze dynamics and vibration characteristics for miscellaneous road conditions.