• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.6
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• pp.108-117
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• 2003

Development of advanced restraint system challenges both restraint and automobile manufacturers to come up with proper airbag design to reduce occupant out-of-position related injury. The important component of the advanced restraint system is the multi stage inflator. The multi stage inflator can independently control two or more airbag inflation stages to maximize occupant protection. The objective of this research is to develop relationship between airbag inflation characteristics, the occupant positions and the airbag design variables. The tests are conducted using five kinds of inflators, two kinds of airbag cushion folding methods and two kinds of tear lines. In the case of inflator, the out-of-position tests are performed with a traditional inflator, a depowered inflator and a dual stage inflator. And the efficiency and injury mechanism are evaluated by analyzing the injury pulses and values. Using this relationship, airbag design guideline is established for airbag aggressivity thresholds and the risk of injury is identified according to occupant positions.

• Nuclear Engineering and Technology
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• v.33 no.3
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• pp.298-306
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• 2001

As fuel burnup proceeds, thermal gradients, differential swelling, and inter-assembly loading may induce assembly duct bowing. Since duct bowing affects the reactivity, such as long or short term power-reactivity-decrement variations, handling problem, caused by top end deflection of the bowed assembly duct, and the integrity of the assembly duct itself. Assembly duct bowing were first observed at EBR-ll in 1965, and then several designs of assembly ducts and core restraint system were used to accommodate this problem. In this study, NUBOW-2D KMOD was used to analyze the bowing behavior of the assembly duct under the KALIMER(Korea Advanced Liquid MEtal Reactor) core restraint system conditions. The mechanical behavior of assembly ducts related to several design parameters are evaluated. ACLP(Above Core Load Pad) positions, the gap distance between the ducts, and the gap distance between the duct and restraint ring were selected as the sensitivity parameter for the evaluation of duct deflection.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.6
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• pp.1-8
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• 2014

Safety performance of a new car is evaluated through USNCAP and their results in the star rating are provided to the consumers. It is very important to obtain high score of USNCAP to appeal their performance to consumers. Therefore the car companies have made the effort to improve their car safety performance. These efforts should satisfy the demand not only to get high score but also to pass the FMVSS, NHTSA regulations on safety. Huge numbers of car crash tests have been conducted on these bases by car companies. However physical tests spend too much cost and time, as an alternative way, the simulation on the car crash could be a solution to reduce the cost and time. Therefore the simulations have been widely conducted in car industry and various researches on this have been reported. In this study, restraint system had been optimized to minimize the injury of female passenger. Belted $5^{th}%ile$ female frontal crash test was selected from various test methods of USNCAP for the study. Initial velocity of the test was 56km/h. The combination injury probability of USNCAP was selected as an objective function and the injury limit value, which was defined in FMVSS, was set to an optimization constraint. Many researches that were similar to this study had been conducted, however most of them had limitation that interaction between airbag and safety belt had not been considered. Contrary to these researches, the interaction was considered in this study.

• Journal of Aerospace System Engineering
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• v.3 no.2
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• pp.1-11
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• 2009

A structural modelling for study on dynamic characteristics of tapered composite aircraft wings in the form of thin-walled beam is presented. The proposed structural model includes effects of transverse shear flexibility exhibited by the advanced composite materials and warping restraint characterizing elastic anisotropy and induced structural couplings. The complex effects of these factors could have a role in more efficient analysis on those structural models.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.53 no.2
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• pp.43-50
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• 2004

Percentage differential characteristic relaying(PDR) has been recognized as the principal basis for power transformer protection. Second harmonic restraint PDR has been widely used for magnetizing inrush in practice. Nowadays, relaying signals can contain 2nd harmonic component to a large extent even in a normal state, and 2nd harmonic ratio indicates a tendency of relative reduction because of the advancement of material. Further, as the power system voltage becomes higher and more underground cables are used, larger 2nd harmonic component in the differential current under internal fault is observed. And then, conventional 2nd harmonic restraint PDR exposes some doubt in reliability. It is, therefore, necessary to develop a new algorithm for performance improvement of conventional protective relaying. This paper proposes an advanced protective relaying algorithm by using voltage-current trend and flux-differential current slope characteristic. To evaluate the performance of the proposed algorithm, we have made comparative studies of PDR, fuzzy relaying and DWT relaying. The paper is constructed power system model including power transformer, utilizing the WatATP, and data collection is made through simulation of various internal faults and inrush. As the results of test, the new proposed algorithm was proven to be faster and more reliable.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.7
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• pp.382-388
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• 2004

The most widely used primary protection for the internal fault detection of power transformers is current percentage differential relaying(PDR). However, the harmonic components could be decreased by magnetizing inrush when there have been changes to the material of iron core or its design methodology. The higher the capacitance of high voltage status and underground distribution, the more differential current includes the second harmonic component during occurrence of an internal fault. Therefore, the conventional harmonic restraint methods need modification. This paper proposes an advanced protective relaying algorithm by fluxt-differential current slope characteristic and trend of voltage and differential current. To evaluate the performance of proposed algorithm, we have made comparative studies of PDR fuzzy relaying, and DWT relaying. The paper is constructed power system model including power transformer, utilizing the WatATP99, and data collection is made through simulation of various internal faults and inrush. As the results of test. the new proposed algorithm was proven to be faster and more reliable.

• International Journal of Control, Automation, and Systems
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• v.1 no.4
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• pp.474-483
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• 2003

Belt drives provide freedom to position the motor relative to the load and this phenomenon enables reduction of the robot arm inertia. It also facilitates quick response when employed in robotics. Unfortunately, the flexible dynamics deteriorates the positioning accuracy. Therefore, there exists a trade-off between the simplicity of the control strategy to reject time varying disturbance caused by flexibility of the belt and precision in performance. Resonance of the system further leads to vibrations and poor accuracy in positioning. In this paper, accurate positioning of a belt driven mechanism using a feed-forward compensator under maximum acceleration and velocity constraints is proposed. The proposed method plans the desired trajectory and modifies it to compensate delay dynamics and vibration. Being an offline method, the proposed method could be easily and effectively adopted to the existing systems without any modification of the hardware setup. The effectiveness of the proposed method was proven by experiments carried out with an actual belt driven system. The accuracy of the simulation study based on numerical methods was also verified with the analytical solutions derived.

• Journal of Auto-vehicle Safety Association
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• v.15 no.3
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• pp.59-65
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• 2023

As advanced driving assistance system (ADAS) and autonomous driving performance continue to improve, existing crash accidents and crash types are changing. Accordingly, the collision angle and the seating posture of the occupant are changed. It is necessary to study how the occupant injury mechanism changes according to these different crash types. In this regard, a representative crash test mode was derived when the automatic emergency braking system (AEB), one of the autonomous driving performance, was applied to the representative car-to-car crash scenario in Korea. The derived crash test mode was used to analyse the mechanisms of collision injuries according to both impact angle and the occupant seating posture (reclined seat-back angle). The results obtained through this study can be utilized as reference data for the development of new crash evaluation methods and improvements in crash restraint systems for enhancing crash safety.

• Journal of Auto-vehicle Safety Association
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• v.7 no.1
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• pp.7-12
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• 2015

NCAP(New Car Assessment Program) makes vehicle manufacturer improve safety performance through free competition and customers guarantee vehicle selection by providing information of vehicle safety. That's why it is important not only to meet the regulation, but also to cope with NCAP. EuroNCAP(European New Car Assessment Program) side tests have conducted by using Progressive MDB and Euro SID II in order to reproduce crash test between two vehicles over 10 years. However various researches report that Progressive MDB and Euro SID II do not reflect evolving vehicle design, impact performance and biofidelity of human. Therefore EuroNCAP has the plan to conduct AE-MDB side crash test using WorldSID which is more evolved from 2015 by replacing Progressive MDB and EuroSID II. Automobile manufacturers need to develop safety performance for new test closely. This paper is to find test set-up parameters which affect into dummy injury instead of restraint system and to research on its tendency. It is processed with mini and small car to know influence as changing vehicle size and also analyzed by DFSS(Design for six sigma) which is one of optimization tools. DFSS is vaildated by simulating CAE with L18 orthogonal array of 6 control factors adjustable as EuroNCAP requirement.

• Proceedings of the KIEE Conference
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• 2003.11a
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• pp.210-212
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• 2003

Conventional PDC relaying with 2nd harmonic restraint makes some doubt in reliability. It can contain second harmonic component to a large extent even during internal fault, and shows a tendency of relative reduction because of the advancement of transformer's core material. It is, therefore, necessary to develop a new algorithm as well as a new technique for the effective and accurate discrimination. This paper deals with advanced algorithm, fuzzy logic based relaying by using flux differential, and a new fault detection criterion logic scheme by using wavelet transform. To comparative analysis of proposed techniques, the paper constructs power system model including power transformer, utilizing the EMTP, and collects data through simulation of various internal faults and magnetizing inrush.