• Proceedings of the Computational Structural Engineering Institute Conference
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• 2008.04a
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• pp.573-578
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• 2008

Finite element analysis of impact response of a motorcycle helmet is presented in this paper. The finite element LS-DYNA3D code is used to simulate the impact response of the helmet including of plastic shell, foam liner, and magnesium headform. Since the maximum accelerations at center of gravity of the headform obtained by numerical analysis and experiment agree well, the numerical simulation is proved to be valid.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2007.04a
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• pp.451-456
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• 2007

A finite element analysis and experiment study of a motorcycle helmet are presented in this paper. The finite element LS-DYNA3D code is used to analyze the helmet. The test specimen, instruments, and setup procedures are described. Since the displacements and Von-Mises stresses obtained by numerical analysis and experiment agree well, the numerical simulation is proved to be valid.

• The Journal of Korean Society for Radiation Therapy
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• v.33
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• pp.15-24
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• 2021

This study is about the introduction and usefulness evaluation of the manufacturing method of the bolus-helmet. Helmet-production for the treatment of scalp tumor patients has been tried and will continue in many creative and various ways. However, Most of the research data did not significantly reduce the psychological burden and physical and physical discomfort that the patient had to bear due to the time and economic cost required for the production of the helmet, the convenience of production, and the complexity of the process. In addition, recently, studies using more advanced technologies and equipment such as 3D-printer technology, which are being studied as a way to increase the treatment effect, are being introduced, but the time, economic cost, and psychological and physical burden are still the sole responsibility of the patient. Isn't it getting worse? The reality is that the thoughts of concern cannot be erased. Therefore, by maintaining the physical properties of the bolus and manufacturing a helmet without incurring additional costs, the physical and physical discomfort aggravated to the patient was reduced and the procedure and time for helmet manufacturing were minimized. In this way, it was possible to reduce the time, economic cost, and physical discomfort required for the production of the helmet, and it was also possible to minimize the psychological burden of the patient, although it is invisible. Additionally, in evaluating the usefulness of helmets, we are able to continuously seek and develop ways to reduce the air-gap interval, and as a result, we will be able to introduce a method to keep it within 2.0mm along with the manufacturing method through this study. I feel very welcome. Finally, I hope that anyone working in the Department of Radiation Oncology will be able to easily manufacture the helmet required for radiation therapy using a bolus through the guide-line on helmet manufacturing provided by this institute. I hope and hope that if you have any questions or inquiries that arise during the production process, please feel free to contact us through the researcher's e-mail or mobile phone at any time.

• Fashion & Textile Research Journal
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• v.20 no.1
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• pp.63-74
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• 2018

The purpose of this study is to investigate the differences in riding characteristics and helmet wearing conditions between bicycle and PMV riders so that the basis data necessary for the development of suitable helmets for each group is provided. For this purpose, riding characteristics and helmet wearing conditions of bicycle and PMV users were investigated using online survey method and then the survey results were interpreted by in-depth interview conducted for bicycle and PMV users. The online survey results showed that the PMV group showed shorter driving distance and more driving frequency than bicycle group. This short driving distance was due to the limitation of battery capacity of PMVs. Helmet wearing rate was significantly lower in PMV group than in bicycle group, which was associated with relatively low chances to drive long distance on the motorway. In the PMV group, the 'urban helmets' were mainly used, in which the appearance of helmet was priorized, but in the bicycle group, the 'road cycle helmets' were mainly used, in which the light weight or ventilation were priorized. Urban helmets caused stronger pain and more fitting problems than road cycle helmets because the head shapes of Koreans were not properly applied to the helmet design. Since the fitting problem and pain intensity were the important causes that making PMV users not wear the helmets, it is necessary to develop the urban helmets reflecting the head shapes of Koreans in order to increase the helmet wearing rate of the PMV users.

• Journal of the Korean Institute of Gas
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• v.13 no.4
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• pp.27-32
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• 2009

This paper presents the stress and deformation behaviors using the finite element method as a function of the thickness of the helmets without the bead frames on the top of the shell structure. The helmet that would provide head and neck protections without causing discomfort to the user when it was worn for long periods of time should be manufactured for increasing the safety and impact energy absorption. The FEM computed results show that when the impulsive force is applied on the top surface of a helmet, the maximum stress and strain have been occurred around the position of an applied impact force, which may lead to the initial failure on the top surface of the helmet shell. As the helmet thickness is decreased from 4mm to 2mm, the impact energy absorbing rate is radically increased, and the maximum stress of the helmet is increased over the tensile strength, 54.3MPa of the thermoplastic material. Thus, the top surface of the helmet should be supported by a bead frame and increased thickness of the shell structure.

• Journal of the Korean Institute of Gas
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• v.13 no.4
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• pp.22-26
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• 2009

In this paper, the displacement behavior and strain energy density characteristics of a safety helmet with various corrugation dampers has been analyzed based on the finite element analysis. The safety helmet is to protect impact forces and to absorb the impact energy. Three different helmet models with a corrugation damper have been compared as functions of the displacement and strain energy density characteristics when the maximum external impulsive force is imposed on the summit of the helmet. The computed FEM results show that the extruded corrugation damper is very useful to increase the damping effect of the helmet. This study indicates that the round corrugation damper may absorb the transferred impact energy successfully. Thus, this paper recommends round and long corrugation damper on the lower part of the helmet as a new design element.

• Archives of Craniofacial Surgery
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• v.15 no.2
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• pp.47-52
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• 2014

Background: Management of positional plagiocephaly by wearing a cranial molding helmet has become a matter of growing medical interest. Some research studies reported that starting helmet therapy early (age 5 to 6 months) is important and leads to a significantly better outcome in a shorter treatment time. The aim of the present study was to evaluate the effectiveness of cranial remodeling treatment with wearing helmet for older infants (${\geq}18$ months). Methods: We conducted a retrospective study of 27 infants with positional plagiocephaly without synostosis, who were started from 2008 to 2012. Every child underwent a computerized tomography (CT) before starting helmet therapy to exclude synostosis of the cranial sutures and had CT performed once again after satisfactory completion of therapy. Anthropometric measurements were taken on using spreading calipers in every child. The treatment effect was compared using cranial vault asymmetry (CVA) and the cranial vault asymmetry index (CVAI), which were obtained from diagonal measurements before and after therapy. Results: The discrepancy of CVA and CVAI of all the patients significantly decreased after cranial molding helmet treatment in older infants (${\geq}18$ months) 7.6 mm from 15.6 mm to 8 mm and 4.51% from 9.42% to 4.91%. Six patients had confirmed successful outcome, and all subjects were good compliance patients. The treatment lasted an average of 16.4 months, was well tolerated, and had no complication. Additionally, the rate of the successful treatment (final CVA ${\leq}5mm$) significantly decreased when the wearing time per was shorter. Conclusion: This study showed that treatment by cranial remodeling orthosis was effective if the patient could wear the helmet longer and treatment duration was somewhat longer than in younger patients, well tolerated in older infants and had no morbidity. This therapeutic option is available and indicated in these older infants before other cranial remodeling surgery.

• Journal of the Korean Institute of Gas
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• v.12 no.3
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• pp.24-30
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• 2008

In this paper, the stress and strain characteristics of a helmet shell structure have been analyzed by using the finite element method and Taguchi's design method as functions of the material properties, the thickness of a helmet, the thickness and the number of a bead frame. The optimized design of the helmets for a firefighter and a gas worker is very important for increasing the strength safety and an impact energy absorption capacity of a helmet shell due to an impulsive external force. Thus, the optimized design data of the helmet indicated that the uniform thickness of a helmet shell may be reduced for reducing the total weight of a helmet and increasing the strain energy absorption rate, but the thickness and the number of a bead frame would be increased for increasing the impact strength of the helmet.

• Journal of the Korean Institute of Gas
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• v.12 no.3
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• pp.31-37
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• 2008

In this paper, the strength analysis has been presented for the stress and strain by using the finite element method for various shell models of the helmets. The advanced helmet that would provide head protection without causing discomfort to the user when it was worn for long periods of time should be manufactured for increasing the safety and workability of the workers. We need a safe, comfortable and light weight of the helmet shell structure. Thus, the helmets had to stand up to the most rigorous conditions encountered for the fire and gas explosion. The FEM computed results show that when the impulsive force is applied on the summit area of a helmet shell structure, the maximum stress and strain have been occurred around the position of an applied impact force, which may lead to the initial failure on the summit of the helmet shell. Thus, the summit area of the helmet shell should be supported by a bead frame and increased thickness of the bead. But the overall thickness of the helmet is to decrease for the light weight of a helmet.

• Journal of the Korean Institute of Gas
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• v.17 no.5
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• pp.37-41
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• 2013

This paper presents the strength safety of stress and deformation behaviors using the finite element method as a function of the thickness of the protective helmets with and without an extruder on the top of the shell structure. The helmet that would provide head and neck protections without causing discomfort to the user when it was worn for long periods of time should be manufactured for increasing the safety and impact energy absorption. The stress analyzed results show that when the impulsive force of 4,540N is applied on the top surface of a helmet, the safe thickness is 3.7mm for the conventional helmet and 3.2mm for the modified new helmet. Based on the deformation analysis, the FEM results recommend that the safe thickness is 3.2mm for the conventional helmet and 2.0mm for the modified new helmet. Thus, it may be more safe design of the helmet, which has an extruded structure on the summit surface of the helmet.