• 한국소음진동공학회논문집
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• 제25권11호
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• pp.739-746
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• 2015

Several damage counting methods can be applied for the fatigue issues of a ground vehicle system using strain data and acceleration data is partially used for a high cyclic loading case. For a vibration test, acceleration data is, however, more useful than strain one owing to the good nature of signal-to-random ratio at acceleration response. The test severity can be judged by the fatigue damage and the pseudo-damage from the acceleration response stated in ISO-16750-3 is one of sound solutions for the vibration test. The comparison of fatigue damages, derived from both acceleration and strain, are analyzed in this study to determine the best choice of fatigue damage over multi-spectral input pattern. Uniaxial excitation test was conducted for a notched simple specimen and response data, both acceleration and strain, are used for the comparison of fatigue damages.

• Journal of Electrical Engineering and Technology
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• 제12권1호
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• pp.396-401
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• 2017

In this paper, a device to analyze gait pattern was developed by using a 2-axis acceleration sensor attached to the foot. The 1st low-pass filter was adapted to limit the frequency band up to 5 Hz. An algorithm to detect the peak value exceeding the threshold voltage of an X-axis acceleration sensor and a Z-axis acceleration sensor was developed and normal and abnormal walking patterns were thus differentiated. Also, MCU and Bluetooth were combined to transfer the data to other MCUs to display on an LCD; the size of the device could then be reduced. The new algorithm and the device allowed the individual walking patterns to be easily measured at a low cost and with less restriction on activities compared to conventional multiple pressure sensors or motion camera system.

• Coupled systems mechanics
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• 제4권1호
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• pp.19-36
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• 2015

Modelling and analysis of a brick masonry building involves uncertainties like modelling assumptions and properties of local material. Therefore, it is necessary to perform a calibration to evaluate the dynamic properties of the structure. The response of the finite element model is improved by predicting the parameter by performing linear dynamic analysis on experimental data by comparing the acceleration. Further, a nonlinear dynamic analysis was also performed comparing the roof acceleration and damage pattern of the structure obtained analytically with the test findings. The roof accelerations obtained analytically were in good agreement with experimental roof accelerations. The damage patterns observed analytically after every shock were almost similar to that of experimental observations. Damage pattern with amplification in roof acceleration exhibit the potentiality of earthquake resistant measures in brick masonry models.

• 전력전자학회논문지
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• 제4권6호
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• pp.616-623
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• 1999

엘리베이터의 속도패턴은 출발시부터 목표 위치 근처에 다다를 때까지의 시간기준 속도패턴과 정밀한 정위치 정지를 위한 거리기준 속도패턴등로 이루어진다. 시간기준 속도패턴에서 거리기준 속도패턴으로 절환시 속도와 가속도의 급격한 변화가 없도록 하여야 패턴 절환시의 충격을 최소화하여 안락한 승차감을 얻을 수 있다. 본 논문에서는 속도패턴 절환 시 항상 속도와 가속도가 연속이 되도록 하고, 또한 목표 위치로의 수렴 속도를 개선한 새로운 엘리베이터 속도패턴 발생 방법을 제시한다.

• 대한전기학회논문지
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• 제44권4호
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• pp.447-452
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• 1995

In this paper a simple method of a position control for brushless DC motor is presented. For precise position control, a high performance torque controller is needed and a novel current control method is proposed. The current controller detects the uncommutating mode current for every 60.deg. (elec. angle) and controls it with PI controller. The current control loop includes the feedforward of back EMF and the feedforward of the neutral voltage between the neutral point of the inverter and the neutral point of the machine. In the position control, the acceleration pattern is calculated from the position reference. Then the speed trajectory is calculated from the acceleration pattern. The experimental results are presented to verify the proposed methods.

• 한국BIM학회 논문집
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• 제9권1호
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• pp.42-51
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• 2019

Maintenance of aging structures has attracted societal attention. Maintenance of the aging structure can be efficiently performed with a digital twin. In order to maintain the structure based on the digital twin, it is required to accurately detect the damage of the structure. Meanwhile, deep learning-based damage detection approaches have shown good performance for detecting damage of structures. However, in order to develop such deep learning-based damage detection approaches, it is necessary to use a large number of data before and after damage, but there is a problem that the amount of data before and after the damage is unbalanced in reality. In order to solve this problem, this study proposed a method based on Generative adversarial network, one of Generative Model, for generating acceleration data usually used for damage detection approaches. As results, it is confirmed that the acceleration data generated by the GAN has a very similar pattern to the acceleration generated by the simulation with structural analysis software. These results show that not only the pattern of the macroscopic data but also the frequency domain of the acceleration data can be reproduced. Therefore, these findings show that the GAN model can analyze complex acceleration data on its own, and it is thought that this data can help training of the deep learning-based damage detection approaches.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집A
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• pp.505-510
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• 2000

Vehicle performances such as fuel consumption and catalyst-out emissions are affected by a driving pattern, which is defined as a driving cycle with the grade in this study. We developed an algorithm to recognize a current driving pattern by using a neural network. And this algorithm can be used in adapting the driving control strategy to the recognized driving pattern. First, we classified the general driving patterns into 6 representative driving patterns, which are composed of 3 urban driving patterns, 2 suburban driving patterns and 1 expressway driving pattern. A total of 24 parameters such as average cycle velocity, positive acceleration kinetic energy, relative duration spent at stop, average acceleration and average grade are chosen to characterize the driving patterns. Second, we used a neural network (especially the Hamming network) to decide which representative driving pattern is closest to the current driving pattern by comparing the inner products between them. And before calculating inner product, each element of the current and representative driving patterns is transformed into 1 and -1 array as to 4 levels. In the end, we simulated the driving pattern recognition algorithm in a temporary pattern composed of 6 representative driving patterns and, verified the reliable recognition performance.

• 대한의용생체공학회:의공학회지
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• 제36권4호
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• pp.109-114
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• 2015

In this study, joint angles of the lower extremity and tibial acceleration and angular velocity were measured during a snowboard simulator exercises in order to evaluate the skill of snowboarders. Ten unskilled and ten expert snowboarders were recruited for the study. A three-dimensional motion capture system and two inertial sensor modules were used to acquire joint movements, acceleration and angular velocity of the lower extremities during snowboard simulator exercises. Pattern variations were calculated to assess variations in the snowboard simulator motion of unskilled and expert snowboarders. Results showed that expert snowboarders showed greater range of motion in joint angles and greater peak to peak amplitude in acceleration and angular velocity for tibia than unskilled snowboarders. The unskilled snowboarders did not show symmetrical shape(same magnitude but opposite direction) in tibial angular velocity during two edge turns in snowboard simulator exercises. The expert snowboarders showed smaller pattern variations for joint angle of lower extremity, tibial acceleration and tibial angular velocity than unskilled snowboarders. Inertial sensor data and pattern variations during the snowboard simulator exercises could be useful to evaluate the skill of snowboarders.

• 한국운동역학회지
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• 제33권4호
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• pp.164-174
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• 2023

Objective: The aim of this study was to quantitatively analyze the impact characteristics of the lower extremity on strike pattern during running. Method: 19 young subjects (age: 26.53 ± 5.24 yrs., height: 174.89 ± 4.75 cm, weight: 70.97 ± 5.97 kg) participated in this study. All subjects performed treadmill running with fore-foot strike (FFS), mid-foot strike (MFS), and rear-foot strike (RFS) to analyze the impact characteristics in the lower extremity. Impact variables were analyzed including vertical ground reaction force, lower extremity joint moments, impact acceleration, and impact shock. Accelerometers for measuring impact acceleration and impact shock were attached to the heel, distal tibia, proximal tibia, and 50% point of the femur. Results: The peak vertical force and loading rate in passive portion were significantly higher in MFS and FFS compared to FFS. The peak plantarflexion moment at the ankle joint was significantly higher in the FFS compared to the MFS and RFS, while the peak extension moment at the knee joint was significantly higher in the RFS compared to the MFS and FFS. The resultant impact acceleration was significantly higher in FFS and MFS than in RFS at the foot and distal tibia, and MFS was significantly higher than FFS at the proximal tibia. In impact shock, FFS and MFS were significantly higher than RFS at the foot, distal tibia, and proximal tibia. Conclusion: Running with 3 strike patterns (FFS, MFS, and RFS) show different impact characteristics which may lead to an increased risk of running-related injuries (RRI). However, through the results of this study, it is possible to understand the characteristics of impact on strike patterns, and to explore preventive measures for injuries. To reduce the incidence of RRI, it is crucial to first identify one's strike pattern and then seek appropriate alternatives (such as reducing impact force and strengthening relevant muscles) on that strike pattern.

• 센서학회지
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• 제3권1호
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• pp.19-25
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• 1994

KOH와 같은 이방성 식각수용액를 사용하여 직각모양의 볼록한 가장자리를 식각할 때, 언더컷팅에 의해 가장 자리가 뭉개어지는 현상이 나타난다. 그래서 이 현상을 방지하기 위해 mass 패턴을 수정할 필요가 있어 보상법에 관한 실험을 하였다. 가속도센서 소자공간을 고려할 경우 정사각형의 보상구조로 mass를 보상하는 것이 적당하다는 결과를 얻었다. 이 결과를 기초로, SDB 웨이퍼를 이용하여 사각뿔 형태의 mass 보상된 실리콘 압저항형 가속도센서를 제조하였다.