• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.25 no.3
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• pp.125-130
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• 2019

Shock and vibration inputs are transmitted from the vehicle through the packaging to the fruit. Inside, these cause sustained bouncing of fruits against each other and container wall. These steady state vibration input may cause serous fruit injury, and this damage is particularly severe whenever the fruit inside the package is free to bounce, and is vibrated at its resonance frequency. The determination of the resonance frequencies of the fruit and vegetables may help the packaging designer to determine the proper packaging system providing adequate protection for the fruit, and to understand the complex interaction between the components of fruit when they relate to expected transportation vibration inputs. Instrumentation and technologies are described for determining the vibration response characteristics of the pears for exporting with frequency range from 10 to 200 Hz, sweep rate of 1 octave/min, sweep method of logarithmic up and down and acceleration levels of 0.2, 0.4, 0.6, 0.8 and 1.0 G considering the domestic transportation environment. The resonance frequency of the pears ranged from 49.04 to 87.16 Hz and the amplitude at resonance was between 0.96 and 4.02 G in test frequency band and acceleration level. The resonance frequency and amplitude at resonance frequency band of the pears decreased with the increase of the sample mass. The multiple nonlinear regression equations for predicting the resonance frequency of the pears were developed using the independent variables such as mass, input acceleration.

• Journal of the Institute of Convergence Signal Processing
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• v.22 no.4
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• pp.199-205
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• 2021

The distributing board in directly installed on the ground or the bottom surface of the building, and when vibrations such as earthquakes or external shocks occur, the possibility of damage or malfunction of electric components such as internal power devices, wiring, and protection relays increases. Recently, the need for a seismic type distributing board is increasing, and research and development of a distributing board having a vibration damping function and product launch are being conducted. In this paper, an IoT-based data collection device system capable of measuring vibration and environmental data of distributing board was designed and implemented. When vibration occurred on the distributing board, data was stored and visualized in the MySQL DB through Node-RED for monitoring and data storage using the MQTT protocol for reliable messaging transmission. The test was conducted by attaching the IoT device of the distributing board, and data was collected in real-time and monitored through Node-RED.

• Korean Journal of Agricultural Science
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• v.30 no.2
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• pp.175-183
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• 2003

Fruit and vegetables are subjected to complex dynamic stresses in the transportation environment. During a long journey from the production area to markets, there is always some degree of vibration present. Vibration inputs are transmitted from the vehicle through the packaging to the fruit. Inside, these cause sustained bouncing of fruits against each other and container wall. These steady state vibration input may cause serious fruit injury, and this damage is particularly severe whenever the fruit inside the package is free to bounce, and is vibrated at its resonance frequency. The determination of the resonance frequencies of the fruit and vegetables may help the packaging designer to determine the proper packaging system providing adequate protection for the fruit, and to understand the complex interaction between the components of fruit when they relate to expected transportation vibration inputs. Instrumentation and technologies are described for determining the vibration response characteristics of the fruits with frequency range 3 to 150 Hz. The computer program for controlling the vibration exciter and the function generator and for measuring the vibration response characteristics of the fruits was developed. The resonance frequency of the pear ranged from 64.5 to 72.2 Hz and the amplitude at resonance was between 1.78 and 2.21 G-rms. The resonance frequency and amplitude at resonance decreased with the increase of the sample mass, and they were slightly affected by mechanical properties such as bioyield deformation and rupture deformation. Regression analysis was performed among the relatively high correlated parameters from the results of correlation coefficient analysis.

• Smart Structures and Systems
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• v.31 no.5
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• pp.469-483
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• 2023

The dynamic characteristics of wind turbine blades are usually monitored by contact sensors with the disadvantages of high cost, difficult installation, easy damage to the structure, and difficult signal transmission. In view of the above problems, based on computer vision technology and the improved YOLOv5 (You Only Look Once v5) deep learning model, a non-contact dynamic characteristic monitoring method for wind turbine blade is proposed. First, the original YOLOv5l model of the CSP (Cross Stage Partial) structure is improved by introducing the CSP2_2 structure, which reduce the number of residual components to better the network training speed. On this basis, combined with the Deep sort algorithm, the accuracy of structural displacement monitoring is mended. Secondly, for the disadvantage that the deep learning sample dataset is difficult to collect, the blender software is used to model the wind turbine structure with conditions, illuminations and other practical engineering similar environments changed. In addition, incorporated with the image expansion technology, a modeling-based dataset augmentation method is proposed. Finally, the feasibility of the proposed algorithm is verified by experiments followed by the analytical procedure about the influence of YOLOv5 models, lighting conditions and angles on the recognition results. The results show that the improved YOLOv5 deep learning model not only perform well compared with many other YOLOv5 models, but also has high accuracy in vibration monitoring in different environments. The method can accurately identify the dynamic characteristics of wind turbine blades, and therefore can provide a reference for evaluating the condition of wind turbine blades.

• Journal of Aerospace System Engineering
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• v.7 no.2
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• pp.55-59
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• 2013

Before avionics equipment are installed in aircraft, several environmental tests such as temperature, vibration, lightning, fire etc. must be conducted. One of the environmental tests is to substantiate protection designs of lightning indirect effect. It can be showed through RTCA DO-160G, section22 "Lightning Induced Transient Susceptibility" test. An additional test of aircraft level is required as well after installation of avionics equipment.

• Journal of Radiation Protection and Research
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• v.32 no.1
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• pp.35-44
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• 2007

Sealed sources have to conducted the tests be done according to the classification requirements for their typical usages in accordance with the relevant domestic notice standard and ISO 2919. After each test, the source shall be examined visually for loss of integrity and pass an appropriate leakage test. Tests to class a sealed source are temperature, external pressure, impact, vibration and puncture test. The environmental test conditions for tests with class numbers are arranged in increasing order of severity. In this study, the apparatus of tests, except the vibration test, were developed and applied to three kinds of sealed source. The conditions of the tests to class a sealed source were stated and the difference between the domestic notice standard and ISO 2919 were considered. And apparatus of the tests were made. Using developed apparatus we conducted the tests for $^{192}Ir$ brachytherapy sealed source and two kinds of sealed source for industrial radiography. $^{192}Ir$ brachytherapy sealed source is classified by temperature class 5, external pressure class 3, impact class 2 and vibration and puncture class 1. Two kinds of sealed source for industrial radiography are classified by temperature class 4, external pressure class 2, impact and puncture class 5 and vibration class 1. After the tests, Liquid nitrogen bubble test and vacuum bubble test were done to evaluate the safety of the sealed sources.

• Smart Structures and Systems
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• v.26 no.4
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• pp.481-493
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• 2020

The negative stiffness spring and inerter are both characterized by the negative stiffness effect in the force-displacement relationship, potentially yielding an amplifying mechanism for dashpot deformation by being incorporated with a series tuning spring. However, resisting forces of the two mechanical elements are dominant in different frequency domains, thus leading to necessary complementarity in terms of vibration control and the amplifying benefit. Inspired by this, this study proposes a Negative Stiffness Inerter System (NSIS) as an earthquake protection system and developed analytical design formulae by fully utilizing its advantageous features. The NSIS is composed of a sub-configuration of a negative stiffness spring and an inerter in parallel, connected to a tuning spring in series. First, closed-form displacement responses are derived for the NSIS structure, and a stability analysis is conducted to limit the feasible domains of NSIS parameters. Then, the dual advantageous features of displacement reduction and the dashpot deformation amplification effect are revealed and clarified in a parametric analysis, stimulating the establishment of a displacement-based optimal design framework, correspondingly yielding the design formulae in analytical form. Finally, a series of examples are illustrated to validate the derived formulae. In this study, it is confirmed that the synergistic incorporation of the negative stiffness spring and the inerter has significant energy dissipation efficiency in a wide frequency band and an enhanced control effect in terms of the displacement and shear force responses. The developed displacement-based design strategy is suitable to utilize the dual benefits of the NSIS, which can be accurately implemented by the analytical design formulae to satisfy the target vibration control with increased energy dissipation efficiency.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.05a
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• pp.185-187
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• 2012

In this paper, the MR fluid damper to the application of the paramagnetic (paramagnetic) particles dispersed in the MR fluid inside the magnet current caused by the MR damper using the principles of the internal fluid delivery yield stress variation is characterized in Silky. In other words, the current strength of the MR fluid damper according to the internal friction coefficient varies phenomenon is to use. The MR fluid damper to control the MCU that you want to use Microchip's dsPIC chips, and current control in order to improve performance by using the PWM and UART communication to an external monitor to monitor the entire system was designed. In this study using MR fluid dampers and dsPIC chip dehydration process happens when a washing machine vibration and noise, vibration and noise reduction sikidorok washing machine protection systems are proposed.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.19 no.3
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• pp.125-131
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• 2013

In order to protect agricultural products against damage by physical load, various shock absorbing materials is used. As the demands of environment protection increase, the use of plastic materials have been restricted. On the other hand, Pulp mold products have some benefits - easy manufacturing, superior shock absorbing and eco-friendly. In order to develop pulp mold tray for melon packaging as shock absorbing packaging material, we investigated physical properties and vibration transmission characters of 180, 200 and 220 g pulp mold tray for melon. As the weight of pulp increased, compression strength and shock absorbing performance increased, while vibration transmissibility decreased. Especially in case of 180g pulp mold tray, it is not suitable for melon packaging because the transmitted vibration acceleration was higher than the forced vibration acceleration. And 200g pulp mold tray is suitable for melon packaging because the vibration transmissibility was lowest in three trays. And the vibration acceleration transmitted to the melon in edge of pulp mold tray was higher than to the melon in center of pulp mold tray. As the result of the simulated transportation test, the firmness of melon packaging using pulp mold tray was higher than that of conventional packaging. Therefore, these results suggest that pulp mold tray packaging could be suitable for melon packaging.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.9
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• pp.841-849
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• 2013

Workers engaged in construction works have been exposed to high levels of noise during their work in tunnels. Noise is one of the major health hazards for employees working in construction sites. The aim of this study is to evaluate the noise levels generating from tunneling equipments such as jumbo drills, backhoes, payloaders, shotcrete machines and service cars. Explosion and turbo fan noises were also monitored. A high precision sound level meter was introduced for measuring LAeq, LAFmax, LAFmin and LCpeak noises in 5 tunneling work sites that were located in Seoul, Kyunggi-do and Kangwon-do areas with NATM and shield methods. The highest noise was recorded by explosion(151.9 dB LCpeak) followed by jumbo drills of higher than 110 dB(A) LAeq. Backhoe normally generated 90~110 dB(A) LAeq while breaking work of rock showed additional around 5~15 dB(A). Noise exposure levels for payloader and shotcrete machine scored more than 90 dB(A) which might be a source of noise-induced hearing loss. Additional research in revealing noise levels from construction equipments operating in tunneling works may enhance the protection of workers who exposed to noise primarily at the sites.