• 대한안전경영과학회지
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• 제11권1호
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• pp.67-73
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• 2009

The goal of this study was to assess the level of vibration in an walking-type cultivator, and to provide a basic information to manage the vibration exposure for farmers. The latent periods of vibration-induced white finger (VWF) were assessed through analyzing the vibration levels and frequency characteristics. Also, vibration acceleration levels based on the daily vibration exposure duration was suggested. The latent periods of vibration-induced white finger were assessed by ISO 5349 method. The latent periods were 4.5 and 10.1 years at 10% and 50% of farmer group, respectively. Also, under ACGIH (American Conference of Governmental Industrial Hygienists) standard, daily vibration exposure duration at 6.7 m/s2 of vibration acceleration has to be less than 4 hours. Therefore, education that maximum working hours should be less than 4 continuous hours is necessary for the operators of walking-type cultivators.

• 대한정형도수물리치료학회지
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• 제28권3호
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• pp.89-99
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• 2022

Background: The purpose of this study was to investigate the effects of physical therapy intervention with local vibration on the physical function of patients with traumatic patella fractures. Methods: This study recruited 6 subjects who had suffered traumatic patella fractures. The study was conducted for an average of 12.8 weeks. Before the treatment (2 weeks post-surgery), they were evaluated using the numeric pain rating scale (NPRS), the Korean-version of the impact of event scale-revised (IES-R-K), pressure pain threshold (PPT), range of motion (ROM) of the knee joint, and the Korean knee injury and osteoarthritis outcome score (K-KOOS) and were reevaluated after 7 and 12 weeks, post-surgery. This study was conducted according to ORIF Patella Fracture Post-Operative Rehabilitation Protocol after applying local vibration. The protocol consists of Phases 1~5 and this study has been applied from phase 2. Results: A comparison of the performance of the participants before and after the intervention showed a decrease in NPRS (9.83±.41→4.83±.98), IES-R-K (68.67±2.73→23.83±2.40), and K-KOOS (Function, Daily living: 70.5±5.96→34.0±3.35, Function, Sports and Recreational activities: 22.83±2.32→10.77±1.37, Quality of Life: 19.33±7.33→7.33±.52) scores. And the ROM (Knee flexion: 30.0±4.47°→128.73±3.6°, Knee extension: -6.83±2.48°→-1.33±1.03°) and PPT (9.67±.52kg/cm²→22.44±2.33kg/cm²) scores increased. Conclusion: These results show that physical intervention with local vibration using a Blackroll® booster and head can help to improve pain, physical function, and psychological status. Also, it was possible to select interventions depending on the patient's condition and the desired goal, using physical intervention with the Blackroll® booster technique.

• Advances in concrete construction
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• 제8권2호
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• pp.77-90
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• 2019

This paper aims to investigate vibration frequency decrease (vibration period elongation) of reinforced concrete (RC) structure with unreinforced infill wall and reinforced infill wall exposed to progressively increased artificial earthquake load on shaking table. For this purpose, two shaking table experiments were selected as a case study. Shaking table experiments were carried on 1:1 scaled prototype one bay one storey RC structure with infill walls. The purpose of this shaking table experiment sequence is to assess local behavior and progressive collapse mechanism. Frequency decrease and eigen-vector evolution are directly related to in-plane and out-of-plane bearing capacities of infill wall enclosure with reinforced concrete frame. Firstly, frequency decrease-damage relationship was evaluated on the base of experiment results. Then, frequency decrease and stiffness degradation were evaluated with applied Peak Ground Acceleration (PGA) by considering strength deterioration. Lastly, eigenvector evolution-local damage and eigenvector evolution-frequency decrease relationship was investigated. Five modes were considered while evaluating damage and frequency decrease of the tested specimens. The relationship between frequency decrease, stiffness degradation and damage level were presented while comparing with Unreinforced Brick Infill (URB) and Reinforced Infill wall with Bed Joint Reinforcement (BJR) on the base of natural vibration frequency.

• 대한물리의학회지
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• 제11권2호
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• pp.1-11
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• 2016

PURPOSE: This study was conducted to assess the effects of local vibration on ankle plantarflexion spasticity and clonus in patients with spinal cord injury. METHODS: The subjects were 14 inpatients with complete or incomplete spinal cord injury (SCI) whose scores were higher than 1 on the Modified Ashworth Scale (MAS) and Spinal Cord Assessment Tool for Spastic Reflexes (SCATS) scale of paraplegia. A randomized single-blind cross-over design was used. Vibration treatment involved a single application of vibration for 10 min in the sitting position, and placebo treatment involved the patient remaining in the sitting position for 10 min. One day after treatment, vibration and placebo treatments were crossed over. Spasticity was measured by using the MAS, and resistance force, by using a hand-held dynamometer; clonus was gauged by using the SCATS scale and clonus burst duration. Additionally, the burst maximal frequency and voluntary ankle dorsiflexion angle of the triceps surae were measured. RESULTS: The application of vibration treatment in the sitting position significantly reduced the MAS scores and resistance force, but significantly increased the dorsiflexion angle of the ankle joint (p<0.05). Furthermore, the vibration treatment diminished the clonus burst duration and SCATS score significantly (p<0.05). Although it reduced the burst maximal frequency of the lateral gastrocnemius and medial soleus, this was significant only for the lateral gastrocnemius. The placebo treatment did not significantly affect any of the test parameters. CONCLUSION: Vibration treatment in the sitting position was effective in cases of spasticity and clonus caused by SCI.

• 대한물리의학회지
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• 제2권2호
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• pp.195-203
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• 2007

Purpose : The purpose of this study was to evaluate the effects of local vibration on knee joints on ability of postural control. Methods : The subjects(50) were divided into control group(25) and vibration group(25). Vibration group was given vibration on knee joint for 10 minutes and control group was given resting for 10 minutes. All subjects of each group were tested on MFT balance tester board for 30 seconds and MFT Balance Test English 1.7 was used to measure ability of postural control pre and post test. Results : 1. Laterality didn't have statistically significant difference pre and post test in both groups(p<0.05). 2. In the control group Body stability didn't have significant difference pre and post test(p>0.05), but had significant difference in the vibration group(p<0.05). 3. At assessment Movement of COG, sector2 in the control group and sector 1, 5 in the experimental group had significant difference pre and post test(p<0.05). Conclusion : From this result vibration on knee have an effect on Body stability. Therefore, the vibration will be effective in treatment of patients who have disability of postural control.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 추계학술대회논문집
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• pp.464-473
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• 2006

This paper summarises theoretical and experimental work on the feedback control of sound radiation from honeycomb panels using piezoceramic actuators. It is motivated by the problem of sound transmission in aircraft, specifically the active control of trim panels. Trim panels are generally honeycomb structures designed to meet the design requirement of low weight and high stiffness. They are resiliently-mounted to the fuselage for the passive reduction of noise transmission. Local coupling of the closely-spaced sensor and actuator was observed experimentally and modelled using a single degree of freedom system. The effect of the local coupling was to roll-off the response between the actuator and sensor at high frequencies, so that a feedback control system can have high gain margins. Unfortunately, only relatively poor global performance is then achieved because of localisation of reduction around the actuator. This localisation prompts the investigation of a multichannel active control system. Globalised reduction was predicted using a model of 12 channel direct velocity feedback control. The multichannel system, however, does not appear to yield a significant improvement in the performance because of decreased gain margin.

• 대한정형도수물리치료학회지
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• 제25권2호
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• pp.65-72
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• 2019

Background: The purpose of this study was to investigate into the effects of physical therapy intervention with local vibration on pain, ROM (range of motion) and psychological status in multiple trauma patients caused by traffic accident. Methods: A patient with multiple trauma were recruited. Before treatment, he was evaluated using numeric pain rating scale (NPRS), Korean-version impact of event scale-revised (IES-R-K), Beck Depression inventory (BDI), passive and active range of motion, and were reevaluated after 4 and 8 weeks of treatment. Results: As a result of comparing the participant before and after the experiment, the score of the IES-R-K and BDI decreased. And the passive and active ROM increased. Conclusion: According to the results above, physical intervention with local vibration by Blackroll Releazer can help improve pain, physical function and psychological status. Also, physical intervention with Blackroll's Releazer technique was able to select interventions depending on the patient's conditional and the desired goal.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 추계학술대회논문집
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• pp.228-229
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• 2008

In this study, we propose an effective method to improve the clarity and period of the beat in a ring structure. Ring is an simplified model of a Korean bell, in which beating vibration and sound are very important features. An equivalent ring theory is applied and finite element analysis on the equivalent ring is performed to determine the condition of the asymmetric element for the clear and proper period beat. The clarity and the period of the beat are improved by attacking asymmetric mass and decreasing local thickness. Using the equivalent ring, the amount and position of the local variation for the required beat condition are determined and the results are verified by experiment.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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• pp.1583-1588
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• 2000

The dynamic characteristics of a HDD suspension system are investigated by finite element analysis and experimental modal analysis. A finite element model of the suspension Type850 was developed for unloaded case. The calculated vibration modes were compared with measurements and agree well in shape and frequency except some local modes. Local thickness and Young's modulus of the finite element model are updated by modal tuning method to develop the precise FE model. A sensitivity matrix of the natural frequencies for some design variables was calculated using finite difference method. Most natural frequencies calculated by the tuned FE model coincide with the measurements and the errors between them are less than 2%.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2006년도 춘계 학술대회 개요집
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• pp.148-150
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• 2006

In this paper, the applicability of an UET(ultrasound excited thermography) for a defect detection of the welded receptacle is described. An UET(ultrasound excited thermography) is a defect-selective and fast imaging tool for damage detection. A high power ultrasound-excited vibration energy with pulse durations of 280ms is injected into the outer surface of the welded receptacle made of Al material. An ultrasound vibration energy sent into the welded receptacle propagate inside the sample until they are converted into the heat in the vicinity of the defect. The injection of the ultrasound excited vibration energy results in heat generation so that the defect is turned into a local thermal wave transmitter. Its local heat emission is monitored by the thermal infrared camera. And they are processed by the image recording system. Measurement was performed on aluminum receptacle welded by using Nd:YAG laser. The observed thermal image revealed two area of defects along the welded seam.