• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2008년도 정기 학술대회
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• pp.362-367
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• 2008

Recently, the use of biaxial hollow slab is increased to reduce noise and vibration of the floor slab. Therefore, an efficient method for the vibration analysis of biaxial hollow slab is required to describe dynamic behavior of biaxial hollow slab. A finite element analysis is one of the method to analyze the biaxial hollow slab. It is necessary to use a refined finite element model for an accurate analysis of a floor slab with an effects of the hollow shape. But it would take a significant amount of computational time and memory if the entire building structure were subdivided into a finer mesh. Thus the proposed method uses equivalent plate model in this study. Dynamic analyses of an example structure subjected to walking loads were performed to verify the efficiency and accuracy of the proposed method.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.117-120
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• 2007

The floor slabs of building structures are often subjected to the periodic force which is induced by vibrating machines or human activity(walking, jumping, running etc). These periodic forces cause excessive oscillation. In order to examine the dynamic characteristics of floor slabs, the dynamic characteristics test is accomplished. Generally, the Impact Hammer and Dynamic Exciter test is used to dynamic characteristics test. But the Impact Hammer test is not suitable to apply in building slabs. In this paper, It compared the performance of the Exciter and Impact Hammer test for dynamic characteristics analysis of floor slabs.

• 한국소음진동공학회논문집
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• 제22권1호
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• pp.15-21
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• 2012

This paper deals with an experimental study on the reaction of muscles by functional electrical stimulation(FES) with the design and fabrication of an ankle reaction apparatus. The ankle reaction apparatus consists of a circuit part and a kinematic part, and it monitors reaction time for a particular angle of joint rotation according to FES. The experimental results showed that the change of the ankle rotation angle was linearly proportional to the change of the magnitude of FES. It also showed that the muscle's reaction time was constant no matter how large the magnitude of the stimulus. The results of this paper can be applied to develop an active-type walking-assistance robot.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 추계학술대회논문집 I
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• pp.114-119
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• 2001

The subjective unwantedness felt from the noise sources in living and office environment has been evaluated by investgating the upper／lower limit of perceptual loudness of the noise. The limits were selected by the subject and the noise sources were analyzed to find out whether there is any correlation with Zwicker parpmeters and ACF fastors. It was found that the loudness of vacuum cleaner noise does not influence its perceived noiseness. Noises implicated in human such as floor walking noise and talking sound, are the most irritating noise in office environment.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2013년도 춘계학술대회 논문집
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• pp.415-418
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• 2013

This paper presents an electromagnetic kinetic energy harvester which is suitable for supplying power for body-worn sensors and personal electric devices. Human motions are investigated by measuring the acceleration signal at each points of the body during walking and running. The dynamic characteristics of the harvester can be calculated from the transfer function of the system. The transduction factor can be calculated from the electromagnetic field analysis by Maxwell software. The prototype of the harvester is designed and manufactured. The theoretical power characteristics are compared with the experiment results.

• 한국구조물진단유지관리공학회 논문집
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• 제21권3호
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• pp.86-92
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• 2017

장스팬 구조물은 사용하중 하에서 바닥진동 문제가 발생할 가능성이 크다. 따라서 구조물 바닥판의 진동성능을 향상시키기 위한 가장 일반적인 방법은 슬래브의 두께를 증가시키는 것이지만 기존의 구조시스템에서 슬래브의 두께를 증가시키면 슬래브 자중의 증가로 건축물 전체의 효율성이 떨어지게 되는 문제점이 있다. 따라서 슬래브의 두께를 증가시키면서도 자중은 크게 증가하지 않는 바닥판 시스템으로 중공슬래브에 관한 관심이 커지고 있는 상황이다. 이에 부력방지능력 및 시공성 향상을 위하여 데크플레이트와 경량성형재를 결합한 형태의 중공슬래브를 개발하였고, 이 중공슬래브를 적용한 실물(mock-up) 건축물에 대한 사용성 검증을 위한 진동성능 평가를 수행하였다. 측정된 결과값을 분석한 결과, 일본건축학회의 "건축물의 진동에 관한 거주 성능 평가지침"에 의하면 1등급인 거실, 침실에 사용해도 될 수준으로 평가되었다.

• 한국소음진동공학회논문집
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• 제15권4호
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• pp.465-473
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• 2005

The impact sounds, generated by the walking of people, the dropping of an object or the moving of furniture, can be a source of great annoyance in residential buildings. The characteristics and level of this impact noise depends on the object striking the floor, on the basic structure of the floor, and on the finish materials of floor. The focus of this paper is to investigate the amount of improvement impact sound pressure level according to the change of the composition method of ceiling and wall. For this purpose, we tested impact sound pressure level of several cases which is the inserting of mineral wool, the increase of the thickness of air layer, the using of anti-vibration rubber in ceiling and attach the mineral wool on wall in the Floor Impact Sound Test Building of KICT. The results show that the composition method of ceiling and wall is more effective in the reduction of light weight impact sound specially in 125Hz and 250Hz.

• 대한정형도수물리치료학회지
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• 제26권2호
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• pp.29-36
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• 2020

Background: The purpose of this study was to determine the effects of whole body vibration (WBV) exercise on lower extremity muscle activity and gait ability in stroke patients. Methods: For this study, 30 stroke patients participated in this study and they were divided into WBV exercise group and sham-WBV exercise group, each group in which consisted of 15 patients. WBV group and sham-WBV group was performed by the patients for five times a week, for six weeks. sEMG was used to measure lower extremity muscle activity. Changes in the activities of the muscles, such as the vatus lateralis (VL), vastus medialis (VM), bicep femoris (BF), gastrocnemius (GCM) muscle, were analysis. Motion analysis system was used to measure gait ability. Gait ability measured the stride length (SL) and walking velocity (WV). Results: According to the results of the comparisons between the groups, after intervention, lower extremity muscle activity of VL (p<.01), VM (p<.01), GCM (p<.01). SL, WV was significant between the group (p<.01). Conclusion: This study showed the WBV exercise is effective for improving increase of muscle activity and gait ability in stroke patients.

• Structural Monitoring and Maintenance
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• 제9권2호
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• pp.201-220
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• 2022

Lateral vibrations of footbridges may induce synchronization between pedestrians and structure itself, resulting in amplification of such vibrations, a phenomenon identified by lock-in. However, investigations about accelerations and frequencies of the structural movement that are related to the occurrence of synchronization are still incipient. The aim of this paper is to investigate conditions that could lead to avoidance of synchronization among pedestrians themselves and footbridge, expressed in terms of peak acceleration. The focus is on the low acceleration range, employed in some guidelines as a criterion to avoid synchronization. An experimental campaign was carried out, employing a prototype footbridge that was set into oscillatory motion through a pneumatic exciter controlled by a fuzzy system, with controlled frequency and amplitude. Test subjects were then asked to cross the oscillating structure, and accelerations were simultaneously recorded at the structure and at the subject's waist. Pattern and phase differences between these signals were analysed. The results showed that test subjects tended to keep their walking patterns without synchronization induced by the vibration of the structure, for structural peak acceleration values up to 0.18 m/s², when frequencies of oscillation were around 0.8 to 0.9 Hz. On the other hand, for frequencies of oscillation below 0.7 Hz, structural peak accelerations up to 0.30 m/s² did not induce synchronization.

• Structural Engineering and Mechanics
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• 제63권6호
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• pp.771-777
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• 2017

The applications of smartphones or other portable smart devices have dramatically changed people's lifestyle. Researchers have been investigating useage of smartphones for structural health monitoring, earthquake monitoring, vibration measurement and human posture recognition. Their results indicate a great potential of smartphones for measuring pedestrian-induced loads like walking, jumping and bouncing. Smartphone can catch the device's motion trail, which provides with a new method for pedestrain load measurement. Therefore, this study carried out a series of experiments to verify the application of the smartphone for measuring human-induced load. Shaking table tests were first conducted in order to compare the smartphones' measurements with the real input signals in both time and frequency domains. It is found that selected smartphones have a satisfied accuracy when measuring harmonic signals of low frequencies. Then, motion capture technology in conjunction with force plates were adopted in the second-stage experiment. The smartphone is used to record the acceleration of center-of-mass of a person. The human-induced loads are then reconstructed by a biomechanical model. Experimental results demonstrate that the loads measured by smartphone are good for bouncing and jumping, and reasonable for walking.