• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.4
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• pp.123-131
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• 2006

The majority of pedestrian fatalities and injuries are caused by vehicle-pedestrian accidents. Recently, it has been recognized as a serious problem. Injuries of occupants in a vehicle have been decreased considerably. However, efforts for protection of pedestrians are still insufficient. These days, many advanced industries are striving for a better protection of pedestrians by using an active hood lift system, rather than reforming the existing structure. In this research, the active hood lift system is designed to enhance the performance for protection. The active hood lift system is analyzed by using the nonlinear finite element method. An optimization problem is formulated by incorporation of the analysis results. Orthogonal arrays are utilized to solve the formulated problem. An iterative optimization algothrithm using orthogonal arrays is utilized for design in the discrete space. It is found that the method can remarkably decrease the number of function evaluations.

• Structural Engineering and Mechanics
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• v.48 no.5
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• pp.661-679
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• 2013

In this work, the safety performance of a commercial motorcycle helmet already placed on the market is assessed. The assessed motorcycle helmet is currently homologated by several relevant motorcycle standards. Impacts including translational and rotational motions are accurately simulated through a finite element numerical framework. The developed model was validated against experimental results: firstly, a validation concerning the constitutive model for the expanded polystyrene, the material responsible for energy absorption during impact; secondly, a validation regarding the acceleration measured at the headform's centre of gravity during the linear impacts defined in the ECE R22.05 standard. Both were successfully validated. After model validation, an oblique impact was simulated and the results were compared against head injury thresholds in order to predict the resultant head injuries. From this comparison, it was concluded that brain injuries such as concussion and diffuse axonal injury may occur even with a helmet certified by the majority of the motorcycle helmet standards. Unfortunately, these standards currently do not contemplate rotational components of acceleration. Conclusion points out to a strong recommendation on the necessity of including rotational motion in forthcoming motorcycle helmet standards and improving the current test procedures and head injury criteria used by the standards, to improve the safety between the motorcyclists.

• Journal of the Ergonomics Society of Korea
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• v.31 no.2
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• pp.379-388
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• 2012

Objective: This study developed a new shower carrier prototype to reduce caregivers' muscle burden and to increase use convenience by reflecting the needs of domestic long-term care institutions. Background: In the long-term care institutions, one of the ADL(Activities of Daily Life) factors is bathing/showering. Recently, bath/shower-assisting equipment is actively being introduced in care institutions to reduce the caregivers' care cost, but most of the domestic equipment was designed to imitate foreign products and rarely reflected the needs of care institutions. Method: Based on Korean elderly people's body information, the bed size(length: 1,900mm, width: 650mm) was set-up, and a variable headrest with a newly designed headform was developed to provide the comfort for the elderly and convenience for caregivers. To reduce caregivers' muscle burden on transferring and showering activities, a 3-step column lifting module equipped with dual actuators(lowest/highest levels from the ground: 600/1,100mm, Stroke: 500mm) was developed, and the wheelbase parameter(length: 1,250mm, width: 580mm) was defined securing the turn-over safety of the shower carrier. The drivability tests were performed for the prototype and foreign product, and the male and female subject's muscle activities were measured through the tests. Results: The structural stability of the shower carrier prototype was secured by finite element analysis, and the muscle activities of the subjects through the drivability tests largely decreased in the prototype, compared to the foreign product. Conclusion: In this study, a new shower carrier prototype was developed to possibly reduce caregivers' muscle burden and to increase use convenience based on the needs of long-term care institutions. It was expected that the drivability performance of the prototype could be relatively superior to that of the foreign product. Application: The results obtained from the study can be applied for the optimal development of a shower carrier including other equipment to effectively care for the elderly.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.8
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• pp.1113-1118
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• 2010

It is requested that the interior compartment of a passenger vehicle must be satisfied with the FMVSS201U regulation, FMH impact test. It is needed the design methodology to find the appropriate structure about the FMH impact. When designing the impact-absorbing structure for the FMH impact test, it is to be noted that the impact absorber must have different performance considering the stiffness of the vehicle as the impact position and approach angle of FMH. In this study, an efficient design methodology was developed by using subcomponent collapse simulation instead of conducting full-vehicle simulation, thereby reducing the time and resources spent. Further, this unit-model simulation helps optimize the impact absorbing structure.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.11
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• pp.1397-1405
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• 2013

The optimal rib pattern design of B-pillar trim considering occupant head protection can be determined by two methods. One is the conventional approximate optimization method that uses the statistical design of experiments (DOE) and response surface method (RSM). Generally, approximated optimum results are obtained through the iterative process by trial-and-error. The quality of results strongly depends on the factors and levels assigned by a designer. The other is a methodology derived from previous work by the authors, called the sequential design of experiments (SDOE), to reduce the trial-and-error procedure and to find an appropriate condition for using artificial neural network (ANN) systematically. An appropriate condition is determined from the iterative process based on the analysis of means. With this new technique and ANN, it is possible to find an optimum design accurately and efficiently.

• Safety and Health at Work
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• v.15 no.1
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• pp.42-52
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• 2024

Background: The lack of headforms that accurately reflect the head characteristics of Koreans and the demographic composition of the Korean population can lead to inadequate FFR testing and reduced effectiveness of FFRs. Method: Direct measurements of 5,110 individuals and 3D measurements of 2,044 individuals, aged between 9 and 69 years, were sampled from the data pool of Size Korea surveys based on the age and gender ratios of the Korean resident demographics. Seven head dimensions were selected based on the ISO 16976-2, availability of Size Korea measurements, and their relevance to the fit performance of FFRs. A principal component analysis (PCA) was performed using the direct measurements to extract the main factors explaining the head characteristics and then the main factors were standardized and remapped to 3D measurements, creating five size categories representing Korean head shapes. Lastly, representative 3D headforms were constructed by averaging five head shapes for each size category. Results: The study identified two main factors explaining Korean head characteristics by the PCA procedure specified in ISO 16976-2 and developed five representative headforms reflecting the anthropometric features of Korean heads: medium, small, large, short & wide, and long & narrow. Conclusion: This study developed representative headforms tailored to the Korean population for conducting total inward leakage (TIL) tests on filtering facepiece respirators (FFRs). The representative headforms can be used for TIL testing by employing robotic headforms to enhance the performance of FFRs for the Korean target population.

• Journal of the korean academy of Pediatric Dentistry
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• v.30 no.4
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• pp.563-575
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• 2003

The purpose of this study was to investigate differences in craniofacial characteristics of professional sportsmen who have practiced since their prepubertal periods. From the standardized lateral and P-A cephalograms of 137 sportsmen, 7 angular, 19 linear, 4 ratio, and 2 index measurements were measured and evaluated by means of statistical methods. The samples were divided into three groups: Group 1; ice hockey(n=17), foot-ball(n=27), basketball(n=16) Group 2; baseball(n=16), gymnastics(n=13), and Group 3; judo(n=18), ssireum(n=10), weight lift(n=20). The results were as follows: It seemed obvious that the cephalic indices of the 3 groups exhibited brachycephalic headform (Group 1; $0.85{\pm}0.04$, Group 2; $0.84{\pm}0.04$, Group 3; $0.83{\pm}0.06$) and there was no statistical difference among the groups (p>0.05). The facial indices of the Group 1 ($0.93{\pm}0.05$) and Group 2 ($0.93{\pm}0.04$) exhibited definite leptoprosopic facial forms while the Group 3 ($0.90{\pm}0.04$) showed more or less euryprosopic facial form, and there appeared significant difference between the Group 1 and 3 (p<0.05), and also between the Group 2 and 3 (p<0.05). There appeared strong relationships between the facial indices and the facial axis angle, mandibular plane angle, total craniofacial height, total facial height, upper anterior dental height, lower anterior dental height, mandibular length, lower anterior facial height ratio, and especially with lower anterior facial height (p<0.001). It seemed that most of the vertical facial measurements of the Group 1 and 2 appeared to be larger than those of the Group 3.