• Journal of the Korea Society for Simulation
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• v.8 no.4
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• pp.25-31
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• 1999

To analyze the impulsive response of a motorcycle helmet, a simulation is performed using the finite element method. Based upon the simulation result, an equivalent one degree of freedom vibrational system is adapted, and transient impulsive responses are analysed to investigate the influence of engineering parameters such as damping, natural frequency, and impact velocity on the impulsive response of the helmet. Maximum gravitational acceleration reduces as the damping factor value increases. When the damping factor value is around 0.6 or larger, the maximum acceleration does not change. With respect to the natural frequency and the impact velocity, it increases linearly. The relationship between head injury criterion(HIC) and maximum gravitational acceleration is also presented. The scheme of this study is expected to be utilized to economize the design process of high quality motorcycle helmets.

• International Journal of Advanced Culture Technology
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• v.10 no.1
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• pp.302-309
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• 2022

Occupational safety accidents are caused by various factors, and it is difficult to predict when and why they occur, and it is directly related to the lives of workers, so the interest in safety accidents is increasing every year. Therefore, in order to reduce safety accidents at industrial fields, workers are required to wear personal protective equipment. In this paper, we proposes a method to automatically check whether workers are wearing safety helmets among the protective equipment in the industrial field. It detects whether or not the helmet is worn using YOLOv5, a computer vision-based deep learning object detection algorithm. We transfer learning the s model among Yolov5 models with different learning rates and epochs, evaluate the performance, and select the optimal model. The selected model showed a performance of 0.959 mAP.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.8 no.1
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• pp.76-87
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• 1998

The concentration of welding fume was measured by 221 welders themselves in chassis frame workplace of the manufactory from February, 1, 1996 to May, 31, 1997. Welding parameters were the welding current and the distance between helmet and arc. Those two optimum conditions were proposed by excess probability analysis using logistic regression, so the best position in the workplace was proposed considering two factors to control the welding fume. The results are as followings; 1) The excess proability of welding fume TLV was over 99% in above 260 Amperes of welding current and also in below 30cm of distanced between helmet and arc. 2) The equation from logistic regression analysis using SPSS/PC+5.02 had the welding current as a independent variable and the excess of welding fume TLV as a dependent variable (p<0.05). Logit(welding fume TLV) = 0.1296 ${\times}$ wlding currnet - 28.8750 3) The equation from logistic regression analysis using SPSS/PC+5.02 had the distance between helmet and arc as a independent variable and the excess of welding fume threshold limit value a, a dependent variable (p<0.05). Logit (welding fume TLV) = -0.6809 ${\times}$ distance between helmet and arc +25.1665 4) Considering both cases or 2) and 3). the result equation is following. (p<0.05). Logit (welding fume TLV) = 0.1346 ${\times}$ welding current -0.3859 ${\times}$ distance between helmet and arc -15.7382 5) The excess probability of welding fume threshold limit value was 100% in above 240 Ampere of welding current. Thus, below 220 Ampere can be suggested to reduce the 40% number of welders who have a excess welding fume threshold limit value. 6) The excess probability of welding fume TLV was 100% in below 34cm of distance between helmet and arc. Thus, over 38cm can be suggested to reduce the 33% number of welders who have a excess welding fume TLV. 7) Considering both 5) and 6) cases, first of all, the best welding current can be 200 Ampere to have a below 15% of welding fume excess probability for the welders who works in distance of 34-37cm. Secondly, to have a below 30% excess probability of welding fume TLV, the working distance must be over 38cm in 220 Ampere and 32cm in 200 Ampere. 8) To reduce the average exposure concentration of welding fume ($8.21{\pm}5.83mg/m^3$), the movable local exhaust system equipped with flexible hoods can be used.

• Journal of the Korea Convergence Society
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• v.10 no.1
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• pp.371-380
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• 2019

Electromygram was measured in three different cases; not wearing of a helmet, wearing of a 920g helmet, and wearing of a 1310g helmet, and it was revealed that there was a high level of muscle activities on the opposite side (sternocleidomastoid muscle) while the head and the neck were moving right and left and muscle activities of the curve and of the hyperextension were found to be not significant. Especially, the presence of a helmet seemed to cause a difference in a level of muscle activities on the deltoid and erector spine muscles while lifting or lowering with a weight placed on the deniz backboard. Therefore, it would be possible to assume that this newly developed smart helmet would not affect muscles around the necks of paramedics if they do not move their necks and heads right and left while lowering or lifting a patient using the deniz backboard. In addition, in case of the deltoid and erector spine muscles, it is shown that an increase in the degree of movement could lead to an increase in the level of muscle activities on the muscles controlling of the corresponding action, which are waist and back muscles. Despite it, it would be possible to prevent possible injuries and/or muscular and skeletal diseases around the lumbar by fully complying with a basic rule of straightening of the waist while making a power-lifting motion.

• Journal of the Korean Institute of Gas
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• v.17 no.6
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• pp.52-57
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• 2013

In this study, the strain energy density, stress and deformation behaviors have been analyzed as functions of a thickness and a force area of protective helmets with and without an extruder on the top of the shell structure using the finite element method. The strain energy density in which is related to the absorption capacity of an impact energy transfer is one of a key element of the helmet safety. The FEM analyzed results show that when the impulsive force of 4,540N is applied on the top surface of the helmets, the maximum stress is linearly reduced for an increased area of impact forces. But, the maximum strain energy density has been reduced for the increased force area. The reduced strain energy density may increase the impulsive forces transferred to the head and neck of helmet wearers, which may decrease the impact energy absorption safety of the helmets. In thus, it is safer design of the helmet in which has an extruded structure on the summit surface, but the modified helmet may decrease the impact energy absorption capacity.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.6
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• pp.1148-1153
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• 2016

The number of cyclists is on the steady growing for leisure and transportation with the increasing interest in health and environment. However, the number of cycling accidents is also increasing steadily due to the lack of safety awareness and regulations. Focusing on this issue, we propose and develop a smart LED bicycle helmet in order to reduce a risk of cycling accident. The main idea is to change status of the LED on the helmet based on the bicycle's movement and provide motion information of the bicycle for others. To control the LED lights on the helmet, we use the Arduino board which communicates with the LED module through serial connection. We decide motion information by using the values from acceleration and GPS sensors of the smartphone. To receive this information from the smartphone, the control board and the smartphone are connected by Bluetooth.

• Journal of the Korea Convergence Society
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• v.11 no.4
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• pp.151-156
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• 2020

The purpose of this study is to design a process for developing wearable sports helmet devices by utilizing IoT server technology, focusing on sports where helmet wear is essential at sports sites. This enables customized training of athletes by continuously accumulating personal biometric information during training, checking players' condition based on data, and informing them of injury prevention and dangerous situations. In addition, the wearable device that can be useful when the training place is likely to damage the physical health due to heat waves or extremes can provide a foundation for improving the performance. Since such technology can be applied not only to the sports field but also to the society such as the industrial field or the underprivileged, it can be expected to be expandable.

• Journal of the Korean Institute of Gas
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• v.12 no.4
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• pp.34-40
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• 2008

Using the finite element method and Taguchi's design technique, the displacement in vertical direction, von Mises stress, and strain energy of the corrugation damper have been analyzed as functions of the extruded length and the thickness of the corrugation damper, and the upper and lower corner radii of the damper. The optimized profile design elements of a corrugation damper are very important for increasing a strain energy absorption capacity of a helmet structure, which is attacked by impulsive external forces. In this study, the optimized design data based on the Taguchi's method was computed as a corrugation damper length of L = 20 mm, a damper thickness of t = 2 mm, the upper corner radius of $R_1=4\;mm$, and the lower corner radius of $R_2=3\;mm$. The optimized design parameters of a corrugation damper indicated that the thickness and extruded length of a corrugation damper may affect to increase the strain energy, which absorbs the impact forces of the helmet.

• Journal of Trauma and Injury
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• v.22 no.2
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• pp.128-133
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• 2009

Purpose: Bicycle riding is a healthy and cheap form of transportation and a popular form of recreation. This study aims to evaluate the epidemiology and the factors affecting the severity of bicycle-related injuries and to find effective methods for preventing injuries. Methods: This is a retrospective study of the patients'characteristics, the injury severity, the injury location, the effect of safety equipment on the bicycle injury based on information collected through the NEDIS (National Emergency Department Information System) from 1,284,429 patients who visited 55 emergency rooms nationwide. Results: During the research period throughout 55 emergency rooms 5,671 patients were seen because of bicycle injuries. The male-to-female ratio was 3.1:1, the median age 28 years old, and 42.6% of the patients were younger than 20 years old. Injury sites were mostly in the extremities(46.7%), the head(32.4%), and the face(14%), and 70.3% of severely injured patients had accompanying head trauma. Males aged 65 and older was possibly associated with severe head trauma. Of the patients who provided helmet information 4.8%(71patients) used helmets, and 95.2%(1392 patients) did not. In this group of patients providing helmet information, none of those wearing helmets died, but 0.4% of those not wearing helmets died. Conclusion: In this study, most bicycle injuries occurred in young adult men. From now, there seems to be a need for more effort on publicity activities on bicycle injuries and on the education of children and teenagers, who show a high incidence rate, and of senior citizens (over 65 years old) who show a high severity rate, about using a safety helmet to reduce the severity of injury.

• Journal of The Korean Astronomical Society
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• v.39 no.4
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• pp.139-145
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• 2006

We have made a comprehensive statistical study on the coronal mass ejections(CMEs) associated with helmet streamers. A total number of 3810 CMEs observed by SOHO/LASCO coronagraph from 1996 to 2000 have been visually inspected. By comparing their LASCO images and running difference images, we picked out streamer-associated CMEs, which are classified into two sub-groups: Class-A events whose morphological shape seen in the LASCO running difference image is quite similar to that of the pre-existing streamer, and Class-B events whose ejections occurred in a part of the streamer. The former type of CME may be caused by the destabilization of the helmet streamer and the latter type of CME may be related to the eruption of a filament underlying the helmet streamer or narrow CMEs such as streamer puffs. We have examined the distributions of CME speed and acceleration for both classes as well as the correlation between their speed and acceleration. The major results from these investigations are as follows. First, about a quarter of all CMEs are streamer-associated CMEs. Second, their mean speed is 413 km $s^{-1}$ for Class-A events and 371 km $s^{-1}$ for Class-B events. And the fraction of the streamer-associated CMEs decreases with speed. Third, the speed-acceleration diagrams show that there are no correlations between two quantities for both classes and the accelerations are nearly symmetric with respect to zero acceleration line. Fourth, their mean angular width are about $60^{\circ}$, which is similar to that of normal CMEs. Fifth, the fraction of streamer-associated CMEs during the solar minimum is a little larger than that during the solar maximum. Our results show that the kinematic characteristics of streamer-associated CMEs, especially Class-A events, are quite similar to those of quiescent filament-associated CMEs.