• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.06a
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• pp.261-262
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• 2008

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.9
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• pp.182-194
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• 1999

Occupant injury in rear end impact is rapidly becoming one of the most aggravating traffic safety problems with high human suffering and societal costs. Although rear end impact occurs at relatively low speed , it may cause permanent disability due to neck injuries resulting from an abrupt moment, shear force , and tension/compression force at the occipital condyles. The analysis is performed for a combined occupant-eat model response, using the SAFE(Safety Analysis for occupant crash Environment) computer program. The computational results are verified by those from sled tests. A parameter study is conducted for many physical and mechanical properties. Seat design has been performed based on the design of experiment process with respect to five parameters; seat-back upholstery stiffness, torsional stiffness of the seat-back. An orthogonal array is selected from the parameter study. A good design has been found from the analysis results based on the orthogonal array. The results show that reductions of stiffness in seat-back upholstery and joint are the most effective for preventing neck injuries.

• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.1
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• pp.51-57
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• 2010

In recent years, a large number of study for rear impact has been conducted and as a result of study, researchers proposed the neck injury criteria and test procedures. But many questions, related to injury criteria and dummy biomechanical levels, remain unresolved. In recently reports, rear impact motions of BioRIDIIg is not humanlike but better than other dummy(HybridIII, RID3d). So, in this paper, 4 times sled test would be done to find the substitutable neck injury criteria in BioRIDIIg. To review corelation trend with neck injury critera and head-neck movement, we compared with recently announced neck injury criteria(NIC, Nkm, T1 ect.) and head-neck X-direction movement in BioRIDIIg. Finally, we find the head-neck X-direction movement on head C.G to T1 point may be considerable as the additional neck injury criteria.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.357-360
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• 2002

Nowadays, the improvement and development of Multi-media, information and communication technology are rapidly processed. And many products, for example, digital camera, digital camcorder, and PDA, are used for them. They need large data storage capacity and small size, light storage system. Due to that, many studies and researches in data storage system have been carried out. Especially, micro drive system was presented by IBM.(1) However, its system is expensive and uneasy to be portable. In ODD technologies, 1 inch drive system is not yet or in processing status.(2) If to be possible and to be come up, it is cheap than HDD system and easy to transfer information. In this paper, a miniaturized actuator(about linch) is designed and tested for ODD system. Specially, it is adapted for NFR(Near-field Recoding) system using SIL(Solid Immersion Lens). It is the dual-servo actuator which consists of a coarse actuator and fine actuator. Its actuating force generation method is VCM(Voice Ceil Motor). The fine actuator has 4-wire suspensions and bobbin wrapped by coil and includes focusing motion as well as tracking motion. The coarse actuator has an actuating coil and V-grooved guide mechanism. Also, the characteristics of the designed actuator is estimated by sine-swept mode and LDV(Laser Doppler Vibro-meter).

• Journal of Auto-vehicle Safety Association
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• v.9 no.1
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• pp.32-36
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• 2017

In order to reduce the damage of life and property caused by an automobile accident, we should design new car models and safety standard with reference to the data analysis and in-depth investigation of the accident. In-depth research and analysis of the current world other than the police investigation team (GIDAS, iGLAD, NHTSA, etc.) and collect in-depth data. Going to develop a safety policy to make it much safer cars based on this data. However, the country still does not have the advantage of KIDAS data Safety Policy Direction. In KNCAP tests, there is nothing in order to protect far side passengers even if far side impact causes approximately 50% injured people. Based on DBs like KIDAS (Korean In-Depth Accident Study) and GIDAS, far side passengers got injured as much as near side passengers did. So as to protect far side passengers, KNCAP has to change the test method of side crashes. In this study, injury severities to compare with ES-2, World SID and Thor dummies and the movements of far and near side passengers, SLED TEST was used.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.5
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• pp.67-75
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• 2011

A new energy absorbing mechanism for car seat was developed to reduce the neck injury in rear impacts. Energy absorbing principle is based on the shear-bolt behavior of thin-walled cast components subjected to static and dynamic loads. Results of shear bolt test using AM60 of Mg alloys showed robust behavior giving an approximately constant mean force during failure processes. Simply designed energy absorbing mechanism was assembled with the recliner between seat backs and seat rails. We have simulated the sled test of seat with dummy under the rear end impact using the finite element method. Results of simulation show that the new seat mechanism reduces thorax acceleration to a considerable extent, but it is not sufficient to mitigate neck injury indices e.g. neck shear force, neck tension force and NIC. With heightened headrest and narrowed backset, the energy absorbing mechanism resulted in good performance of protecting the neck injuries.

• Journal of Auto-vehicle Safety Association
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• v.5 no.2
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• pp.45-50
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• 2013

The whiplash Injuries due to rear collision occur frequently. As result, in many countries, seat performance is being assessed and developed to improve head whiplash injury in rear collision of passenger car. This study compares whiplash assessment methods in each country. Using the DFSS(Design for Six Sigma) method, the correlation between influence parameters of head restraints and whiplash injury criteria is analyzed. Four control factors are used in this study. And total 11 whiplash injury criteria from NCAP(New Car Assessment Program) of Korea, Europe, China and IIHS(Insurance Institute for Highway Safety) of USA are used for output response. By the experimental design, L9 orthogonal coordinate system is configured and is tested by sled test equipment, twice. By using average assay value and ANOVA, the correlation between control factors and injury criteria has been comprehended. Optimization design of head restraint according the regional seat safety assessment was derived through the correlation.

• Sleep Medicine and Psychophysiology
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• v.11 no.1
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• pp.29-36
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• 2004

Objectives: Sound and light (SL) stimulation has been used as a method to induce some useful mental states in the fields of psychology and psychiatry. It is believed that sound and light entrainment device (SLED) has some specific effects through synchronization of EEG in patients who use it. Theta frequency is believed to stimulate deep relaxation and short term memory processing. This study was conducted to evaluate if 4-10 Hz SL stimulation can induce relaxation and improve short term memory function. Methods: Ten medical students with no medical or psychiatric problems participated in this study. Subjects were randomly divided into two groups. One group was applied with real SLED was applied to one group (R group) and pseudo SLED to the other group (P group). The two groups were exposed to SL stimulation with SLED 15 minutes a day for 5 days, and after two days rest the two groups were switched over. The Korean Wechsler Adult Intelligence Scale (K-WAIS), Academic Motivation Tests (AMT), Test Anxiety Scale (TAS), Korean Auditory Verbal Learning Test (K-AVLT), and digit span were used to evaluate short term memory. Spielberger's State-Trait anxiety inventory and heart rate variability (HRV) test were used to evaluate degree of relaxation. Results: Compared with S group, R group showed a significant improvement in K-AVLT and digit span after a single application of SL stimulation. But 5-day long application did not reveal any differences between the two groups. A significant change in HRV was observed in 5-day long application of SL stimulation after being switched over to other SLED. Conclusion: This pilot study suggests that 4-10 Hz SL stimulation has some positive influences on short term memory and relaxation.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.3B
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• pp.193-201
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• 2012

In the last decade, heavy rainfall induced debris flow events have been remarkably occurred in Korea. Consequently, debris flow is becoming one of the most dangerous natural phenomena in mountainous area. Understanding and correct predicting of the runout distance of debris flow is an essential prerequisite for developing debris flow hazard map and prevention technology. Based on the simple and widely used sled model, in this study, we analyse the net efficiency of debris flows which is a dimensionless constant (=1/R) and defined by the ratio of the horizontal runout distance L from the debris flow source to deposit and the vertical elevation H of the source above the deposit. The analysis of field data observed in total 238 debris flow events occurred from 2002 to 2011 reveals that the representative value of the net efficiency of debris flows in Korea is 4.3. The data observed in Gangwon province where is the most debris flow-prone area in Korea shows that debris flows in Inje area have the runout distance longer than those in Pyongchang and Gangneung. Overall features of the net efficiency of debris flows observed in the central Korea are similar to those in the southern Korea. The estimation based on aerial photographs and available depositional conditions appears to overestimate the net efficiency compared to estimation based on the field observations, which indicates that appropriate depositional conditions need to be developed for debris flows in Korea.

• Journal of Auto-vehicle Safety Association
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• v.7 no.3
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• pp.7-13
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• 2015

Occupant protection performance in frontal crashes has been developed and assessed for mainly front seat occupants over many years, and in recent years protection of rear seat occupants has also been extensively discussed. Unlike the front seats, the rear seats are often occupied by children seated in rear-facing or forward - facing child restraint systems, or booster seats. In the ENCAP, child occupant protection assessments using 18-month-old(P1.5) and 3-year-old(P3) test dummies in the rear seat have already been changed to new type of 18-month-old (Q1.5)and 3-year-old(Q3) test dummies. In addition, ENCAP are scheduled with the development and introduction of test dummies of 6-year-old (Q6) and 10.5-year-old children(Q10) starting 2016. In KNCAP, Q6 and Q10 child dummies will be introduced in 2017 as well. Automobile manufacturers need to develop safety performance for new child dummies closely. In this paper, we focused on Q6 and Q10 child dummies sitting in child restraint system. Offset frontal crash tests were conducted using two types of test dummies, Q6 and Q10 child dummies, positioned in the rear seat. Q6 and Q10 were used to compare dummy kinematics in rear seating positions between Q6 behind the driver's seat and Q10 behind the front passenger's seat. The full vehicle sled test results of both dummies were conducted with different restraint systems. It showed that several injury and image data was collected as the result of the full vehicle sled test. Based on the results of these investigations, this paper describes which factor is most important and combination is the best performance when evaluating rear seat occupant protection for Q6 and Q10 child dummies.