• Smart Structures and Systems
• /
• v.18 no.2
• /
• pp.249-265
• /
• 2016

A bimorph piezoelectric energy harvester is developed for harvesting energy under the vortex induced vibration and it is integrated to a host structure of a trapezoidal plate without changing its passive dynamic properties. It is aimed to select trapezoidal plate as similar to a vertical fin-like structure which could be a part of an air vehicle. The designed energy harvester consists of an aluminum beam and two identical multi fiber composite (MFC) piezoelectric patches. In order to understand the dynamic characteristic of the trapezoidal plate, finite element analysis is performed and it is validated through an experimental study. The bimorph piezoelectric energy harvester is then integrated to the trapezoidal plate at the most convenient location with minimal structural displacement. The finite element model is constructed for the new combined structure in ANSYS Workbench 14.0 and the analyses performed on this particular model are then validated via experimental techniques. Finally, the energy harvesting performance of the bimorph piezoelectric energy harvester attached to the trapezoidal plate is also investigated through wind tunnel tests under the air load and the obtained results indicate that the system is a viable one for harvesting reasonable amount of energy.

• Structural Engineering and Mechanics
• /
• v.54 no.6
• /
• pp.1217-1244
• /
• 2015

In this research a theoretical and numerical study on a bridge damage detection procedure is presented based on vibration measurements collected from a set of accelerometers. This method, referred to as "Adjoint Variable Method", is a sensitivity-based finite element model updating method. The approach relies on minimizing a penalty function, which usually consists of the errors between the measured quantities and the corresponding predictions attained from the model. Moving mass is an interactive model and includes inertia effects between the model and mass. This interactive model is a time varying system and the proposed method is capable of detecting damage in this variable system. Robustness of the proposed method is illustrated by correct detection of the location and extension of predetermined single, multiple and random damages in all ranges of speed and mass ratio of moving vehicle. A comparative study on common sensitivity and the proposed method confirms its efficiency and performance improvement in sensitivity-based damage detection methods. In addition various possible sources of error, including the effects of measurement noise and initial assumption error in stability of method are also discussed.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.10 no.5
• /
• pp.190-198
• /
• 2002

Full scale durability test in the laboratory is an essential of any fatigue life evaluation of components or structures of the automotive vehicle. Component testing is particularly important in today's highly competitive industries where the design to reduce weight and production costs must be balanced with the necessity to avoid expensive service failure. Generally, hydraulic road simulator is used to carry out the fatigue test and the vibration test. In this paper, the algorithm and software to realize the real road profile are developed. The operation software for simultaneously controlled multi-axial road simulator is developed and the input and output data are displayed window based PC controller in the real time. Futhermore, the software to generate the real road profile are developed. The validity of the software are verified by applying the belgian road, the city road, the highway, and the gravel road. The results of the above experiment show that the real road profiles are realized well after 10th iteration.

• Journal of the Korean Society of Safety
• /
• v.29 no.4
• /
• pp.172-179
• /
• 2014

This research suggests that the regulation, design and improvement of domestic and international ambulances so that make the basis for the future ambulance in Korea. It is true that the diversification of current disasters, increasing elderly population, the increase in emergency patients, due to the lack of effective transfer system, emergency vehicle's performance problem, and the aging of ambulances cause have difficulty in providing effective emergency services in domestic country. Therefore, in order to improve the effectiveness of ambulance, the history of ambulance, other relevant provisions include international, design and directions to be improved were investigated, and also research directions of the ambulance are suggested in domestic country. In this research, suggests the following conclusions to improve domestic ambulance 1. Through standardization of the spacing and location of an ambulance is needed to maximize the treatment room. 2. The interior of the ambulance design for hygiene and infection control should be included. 3. Stretcher and equipment are designed to be fitted to each other should be standardized. 4. Especially during transfer maintain the road, noise, vibration, and shock-absorbing function to emphasize the importance. 5. The improvement of ergonomic design is necessary for the possibility of applying to many people.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.55 no.10
• /
• pp.491-497
• /
• 2006

For high efficiency and easy speed control of brushless DC (BLDC) motor, the demand of BLDC motor is increasing. Especially demand of interior permanent magnet (IPM) BLDC with high efficiency and high power in electric motion vehicle is increasing. However, IPM BLDC basically has a high cogging torque that results from the interaction of permanent magnet magnetomotive force (MMF) harmonics and air-gap permeance harmonics due to slotting. This cogging torque generates vibration and acoustic noises during the driving of motor. Thus reduction of the cogging torque has to be considered in IPM BLDC motor design by analytical methods. This paper proposes the cogging torque reduction method for IPM BLDC motor. For reduction of cogging torque of IPM BLDC motor, this paper describes new technique of the flux barriers design. The proposed method uses sinusoidal form of flux density to reduce the cogging torque. To make the sinusoidal air-gap flux density, flux barriers are applied in the rotor and flux barriers that installed in the rotor produce the sinusoidal form of flux density. Changing the number of flux barrier, the cogging torque is analyzed by finite element method. Also characteristics of designed model by the proposed method are analyzed by finite element method.

• Proceedings of the KSR Conference
• /
• 2008.11b
• /
• pp.1776-1781
• /
• 2008

To reduce interior noise of running vehicles, a floating floor construction has been widely used in recent railway industry. Among the key factors of the floating floor design, dynamic stiffness is of most important in acoustical point of view. Sometimes hard rubber type supports have often been selected due to the other design constraints such as heavy load condition, durability of rubber element and its cost etc., even though it seems like the softer support, the better isolation of noise and vibration. In this paper two representative floor supports have been considered to evaluate their effectiveness in interior noise contribution: one is a soft rubber and another is a relatively hard one. From the measured dynamic stiffness of the specimens, equivalent stiffness of actual floating floor has been derived to use in the analytical models. Calculated air-borne and structure-borne noise insulation properties of the floating floors have been compared with experiments in prototype car. In full car model interior noise levels of running vehicles have been predicted to quantify the effectiveness of the two different floating support materials and verified through the measured inside noise levels of actual train as well. By comparison with difference of running noise levels two materials for floor support can be investigated quantitatively so that it could be applied in floating floor design.

• The Journal of Economics, Marketing and Management
• /
• v.11 no.2
• /
• pp.13-22
• /
• 2023

Purpose: The purpose of this study is to examine the policy implications of establishing a compact city in Seoul, analyzing whether it is an appropriate and efficient eco-friendly housing supply alternative. Research design, data, and methodology: The analysis criteria include efficiency, safety, and comfort, with efficiency encompassing economic, energy, and public transport links' efficiency. Safety and comfort are aspects of eco-friendliness, housing safety, and improvement in living environments. Results: In terms of economic efficiency, compact cities are a less expensive option than purchasing land for housing construction. To increase energy efficiency, we plan to adopt eco-friendly energy sources. Transportation efficiency is high in locations near public transport stations. To enhance safety and comfort, we intend to create large-scale parks and forests in Seoul. To ensure residential safety, measures will be taken to reduce road vibration, vehicle noise, and scattering dust. Conclusions: Selecting an appropriate location that provides convenient public transportation is essential for creating a compact city for housing in a large city. Combining a compact and smart city is necessary, and implementing smart technologies is needed to prevent dust, noise, and vibrations, which are undesirable in a residential environment.

• International Journal of Advanced Culture Technology
• /
• v.11 no.1
• /
• pp.337-342
• /
• 2023

Since the electric vehicle uses an electric motor, problems have arisen as the driver hears the inherent noise of the motor or external noise, which was not a problem in the past, due to the overall lower noise environment than when using an internal combustion engine. Therefore, the purpose of this paper is to reduce the noise and vibration of electric motors for electric vehicles, and recently, to increase the speed of high-power, high-efficiency electric motors in a small size, and to develop low-noise motors, IPM motors are applied to produce 35KW electric motors for electric vehicles. A motor for low noise was designed and implemented. N-T Curve and efficiency map were confirmed as the final result of developing a 35KW low-noise motor for electric vehicles by applying the IPM motor applied in this paper. Based on 3500 rpm, Max Torque [Nm]: 121.15, Max Power [KW]: 44.04, and Max Efficiency [%]: 97.65, showing high efficiency.

• Smart Structures and Systems
• /
• v.31 no.5
• /
• pp.501-516
• /
• 2023

Dynamic irregularity and acceleration of bridges subjected to high-speed trains provide crucial information for comprehensive evaluation of the health state of under-track structures. This paper proposes a novel approach for real-time estimation of vertical track dynamic irregularity and bridge acceleration using deep generative adversarial network (GAN) and vibration data from in-service train. The vehicle-body and bogie acceleration responses are correlated with the two target variables by modeling train-bridge interaction (TBI) through least squares generative adversarial network (LSGAN). To realize supervised learning required in the present task, the conventional LSGAN is modified by implementing new loss function and linear activation function. The proposed approach can offer pointwise and accurate estimates of track dynamic irregularity and bridge acceleration, allowing frequent inspection of high-speed railway (HSR) bridges in an economical way. Thanks to its applicability in scenarios of high noise level and critical resonance condition, the proposed approach has a promising prospect in engineering applications.

• Smart Structures and Systems
• /
• v.31 no.1
• /
• pp.29-43
• /
• 2023

This study investigates the possibility of damage detection of a real bridge by means of a modal parameter-based finite element (FE) model update. Field moving vehicle experiments were conducted on an actual steel plate girder bridge. In the damage experiment, cracks were applied to the bridge to simulate damage states. A fast Bayesian FFT method was employed to identify and quantify uncertainties of the modal parameters then these modal parameters were used in the Bayesian model update. Material properties and boundary conditions are taken as uncertainties and updated in the model update process. Observations showed that although some differences existed in the results obtained from different model classes, the discrepancy between modal parameters of the FE model and those experimentally obtained was reduced after the model update process, and the updated parameters in the numerical model were indeed affected by the damage. The importance of boundary conditions in the model updating process is also observed. The capability of the MCMC model update method for application to the actual bridge structure is assessed, and the limitation of FE model update in damage detection of bridges using only modal parameters is observed.