• International Journal of Precision Engineering and Manufacturing-Green Technology
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• v.5 no.5
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• pp.571-581
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• 2018

In the present study, monitoring of elliptical vibration cutting process by utilizing internal data in the ultrasonic elliptical vibration device without external sensors such as a dynamometer and displacement sensor is investigated. The internal data utilized here is the change of excitation frequency, i.e. resonant frequency of the device, voltages applied to the piezoelectric actuators composing the device, and electric currents flowing through the actuators. These internal data change automatically in the elliptical vibration control system in order to keep a constant elliptical vibration against the change of the cutting process. Correlativity between the process and the internal data is described by using a vibration model of ultrasonic elliptical vibration cutting and verified by several experiments, i.e. planing and mirror surface finishing of hardened die steel carried out with single crystalline diamond tools. As a result, it is proved that it is possible to estimate the elements of elliptical vibration cutting process, e.g. tool wear and machining load, which are important for stable cutting in such precision machining.

• Design & Manufacturing
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• v.17 no.3
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• pp.34-40
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• 2023

In this study, real-time collection of mold vibration signals during injection molding processes was achieved through IoT devices installed on the mold surface. To analyze changes in the collected vibration signals, injection molding was performed under six different process conditions. Analysis of the mold vibration signals according to process conditions revealed distinct trends and patterns. Based on this result, cosine similarity was applied to compare pattern changes in the mold vibration signals. The similarity in time and acceleration vector space between the collected data was analyzed. The results showed that under identical conditions for all six process settings, the cosine similarity remained around 0.92±0.07. However, when different process conditions were applied, the cosine similarity decreased to the range of 0.47±0.07. Based on these results, a cosine similarity threshold of 0.60~0.70 was established. When applied to the analysis of mold vibration signals, it was possible to determine whether the molding process was stable or whether variations had occurred due to changes in process conditions. This establishes the potential use of cosine similarity based on mold vibration signals in future applications for real-time monitoring of molding process changes and anomaly detection.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.10a
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• pp.271-276
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• 2011

The working conditions of construction equipments such as excavators, wheel loaders and haulers are very tough and severe in fact. To design main components of construction equipment under the severe environment, it's important for engineers to consider design for vibration durability point of view at the early stage of product development process. Radiator as a cooling unit of construction equipment is one of critical components to apply design for vibration. We present a design for vibration process and methodology on the radiator system in construction equipment industries. From the natural frequency and the random vibration analysis based on field vibration test data, we could find current status of radiator layout design to develop and made best layout specification of radiator design to decide for product development process at the early stage.

• Journal of the Ergonomics Society of Korea
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• v.32 no.4
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• pp.309-319
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• 2013

Objective: The aim of this study is to review and summarize human vibration measurement process, and necessity and methods of frequency weightings for human vibration. Background: Prolonged human exposure to hand-arm vibration and whole-body vibration can result in a range of adverse conditions and the development of occupational diseases such as vibration white finger. For preventing these adverse effects, it is important to correctly apply human vibration measurement process. Method: This manuscript was based on the review and summary of mechanical and human vibration relevant texts, academic papers, materials obtained through web surfing. Results: This manuscript summarizes human vibration measurement process described in ISO standards and relevant texts. The sensitivity of the human body to mechanical vibration is known to be dependent on both the frequency and direction of vibration. To take this into account, varying frequency weighting functions have been developed, and RMS frequency-weighted accelerations are used as the most important quantity to evaluate the effects of vibration on health. ISO provided nine frequency weighting functions in the form of curves and tables. Researches on frequency weightings are focused on development and validation of new frequency weightings to truly reflect the relationship between vibration exposure and its adverse effects. Application: This would be useful information for systematically applying human vibration measurement and analysis process, and for selecting appropriate frequency weighting functions.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.3
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• pp.185-192
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• 2004

Vibration table is required to obtain high packing density in expendable pattern casting process. Packing density. which is an important manufacture factor, depends on the vibration pattern induced by vibration table. In general, circular vibration pattern is recognized as the best pattern. The existing vibration table is investigated to identify current vibration pattern and consider a countermeasure. Modal test is utilized to identify the dynamic characteristics of vibration table, and finite element method is used to propose the improved design. In simulation using finite element method, the position of stiffeners is obtained to satisfy the required dynamic characteristics.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11a
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• pp.433-438
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• 2001

This study is performed to evaluate hand-arm vibration syndrome(HA VS) of the workers in swaging process. Vibration measurement and assessment of human exposure are based on the international standard(ISO 5349). Triaxial acceleration of each operation and exposure time are measured to predict the periods before finger blanching, As results, it is found that acceleration is concerned with the diameter of pipes in swaging process, and also found that combined work is more harmful than a single operation.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.9
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• pp.101-109
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• 2001

The simulated die casting process in which the traditional plaster casting process is combined with rapid prototyping technology is being used to produce Al, Mg and Zn die casting prototypes. Because of lower mechanical properties induced by the large grain structure and incomplete filling, conventional plaster casting is not suitable for the simulated die casting process. A plaster casting process with pressurized vibration was developed for the simulated die casting process[5]. In this paper, numerical simulation for the filling stage of the process has been performed to show the effect of the pressurized vibration for complete filling. Treatment of boundary condition based on the finite element method has been proposed for imparted pressurized vibration in the plaster casting process.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.160-165
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• 2002

Vibration table is required to obtain high packing density in expendable pattern casting process. Packing density, which is an important manufacture factor, depends on the vibration pattern induced by vibration table. In general, circular vibration pattern is recognized as the best pattern. The existing vibration table is investigated to identify current vibration pattern and consider a countermeasure. Modal test is utilized to identify the dynamic characteristics of vibration table, and finite element method is used to present the improved design.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.13 no.3
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• pp.96-102
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• 2014

This study focused on the effects of ultrasonic vibration on a machined surface of Al6061 material in the endmill cutting process. It is known that ultrasonic vibration greatly increases the efficiency of the machining process when cutting or grinding. An ultrasonic vibration table was developed for application to ultrasonic vibration endmill machining experiments.Inthisstudy,the surface roughness and actual depth of the cut measured confirm the effects of ultrasonic vibration. As a result of the experiments, the actual depth of the cut increased during endmill machining when using ultrasonic vibration. The surface roughness was improved with increases in the amplitude of the vibration and the depth of the cut.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.10a
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• pp.254-258
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• 2009

In this paper, the low frequency vibration forming system is developed for micro-patterns formation on the metal substrate. many researchers have studied about micro-forming technologies such as micro deep drawing, press forming, forging, extrusion etc. for the formation of precise micro-patterns on the surface of metal substrates, multi-step forming process must be used to improve qualifies of the deformed patterns. Since the low frequency vibration forming system could easily deform the surface of metal substrates, several steps of multi-step forming process should be removed by using the low frequency vibration forming system. In order to find optimal process conditions, we have carried out low frequency vibration forming process with varying the vibration frequency from 110Hz to 500Hz.