• 대한기계학회논문집A
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• 제37권1호
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• pp.129-135
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• 2013

자동차 측면 충돌사고는 충격흡수공간이 충분하지 않기 때문에 정면 충돌사고와는 달리 발생빈도에 비하여 탑승자의 상해비율이 매우 높은 경향을 나타낸다. 측면 충돌사고 발생시 탑승자를 보호하기 위하여 전세계 각국에서는 자동차안전기준 및 안전도평가 등의 법규를 시행 및 강화하고 있다. 그러나 차체 자체의 충격흡수력을 이용한 수동 안전방식으로는 협소한 공간에 기술을 적용하는데 한계가 있다. 커튼 에어백은 측면 에어백과 함께 현재로서는 측면충돌시 탑승자를 보호하는 가장 효과적인 시스템이다. 본 연구에서는 측면 충돌사고 발생시 탑승자의 머리상해지수를 감소시키기 위한 커튼 에어백의 최적설계를 수행하였다. 충돌 시뮬레이션을 바탕으로 직교배열표와 일원표, 그리고 반응표면법을 순차적으로 적용하고 각각의 결과에 대하여 확인실험으로 검증하여 커튼 에어백의 최적설계를 수행하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 추계학술대회 논문요약집
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• pp.69-69
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• 2003

• 한국자동차공학회논문집
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• 제14권4호
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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.

• 대한기계학회논문집A
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• 제28권9호
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• pp.1399-1407
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• 2004

Structural optimization has been carried out in continuous design space or in discrete design space. Generally, available designs are discrete in design practice. However, the methods for discrete variables are extremely expensive in computational cost. An iterative optimization algorithm is proposed for design in a discrete space, which is called a sequential algorithm using orthogonal arrays (SOA). We demonstrate verifying the fact that a local optimum solution can be obtained from the process with this algorithm. The local optimum solution is defined in a discrete design space. Then the search space, which is a set of candidate values of each design variables formed by the neighborhood of a current design point, is defined. It is verified that a local optimum solution can be found by sequentially moving the search space. The SOA algorithm has been applied to problems such as truss type structures. Then it is confirmed that a local solution can be obtained by using the SOA algorithm

• 한국자동차공학회논문집
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• 제7권6호
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• pp.144-155
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• 1999

An occupant analysis code SAFE (Safety Analysis For occupant crash Environment) is utilized to simulate and improve the crash performance of an energy absorbing steering system. The safety standard FMVSS 203 is simulated and used for design evaluations . Segments and contact elliposids are utilized to model the bod blocks and the components of the steering system with SAFE. Spring-damper elements and force-deflection characteristics are utilized to model the energy absorbing components such as the plate and the polyacetal molding. The plate absorbs the impact energy through tensile deformation . Whereas, the polyacetal molding absorbs the impact energy through compression. the body block test is carried out to validate tie simulation model, and real component tests are performed to extract the force-deflection curves . After the model is validated , the parameter study is carried out to evaluate the crash performance of the energy absorbing components. A performance measure is defined for the parameter study. Using the results of the parameter study and managing the orthogonal arrays, optimum design values of energy absorbing components are determined to minize the occupant injury.

• Ocean and Polar Research
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• 제26권2호
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• pp.333-339
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• 2004

This paper is concerned with an experimental investigation about tractive performance of a tracked vehicle on extremely soft soil. A tracked vehicle model with principal dimensions of $0.9\;m(L)\;{\times}\;0.75\;m(B)\;{\times}\;0.4\;m(H)$ and the weight of 167 kg was constructed with a pair of driving chain links driven by two AC-servo motors. The tracks are configured with detachable grousers with variable span. Deep seabed was simulated by means of bentonite-water mixture in a soil bin of $6.0\;m(L)\;{\times}\;3.7\;m(B)\;{\times}\;0.7\;m(H)$. Slip of vehicle and driving torque of motor were measured with respect to experimental variables; grouser span, grouser chevron angle, driving speed, drawbar-pull weight, position of center-of-gravity and weight. $L_8$ orthogonal array is adopted for DOE (Design Of Experiment). The effects of experiment variables on traction performance are evaluated.

• 대한기계학회논문집A
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• 제24권12호
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• pp.2952-2962
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• 2000

The design of experiment(DOE) is getting more attention in the engineering community since it is easy to understand and apply. Recently, engineering designers are adopting DOE with orthogonal arrays when they want to design products in a discrete design space. In this research, a design flow with orthogonal arrays is defined for structural design according to the general DOE. The design problem is defined as a general structural optimization problem. Sensitivity information is evaluated by the analysis of variance(ANOVA), and an optimum design is determined from analysis of means(ANOM). Interactions between design variables are investigated to achieve additivity which should be valid in DOE. When strong interactions exit, a method is proposed. Some methods to consider the problem are suggested.

• 대한기계학회논문집A
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• 제29권9호
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• pp.1161-1168
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• 2005

As a result of vehicle maintenance of rocker arm shaft for 4-cylinder SOHC engine, failure analysis of rocker arm shaft is needed. Because more than $30\%$ of vehicles investigated have been fractured. Failure analysis is classified into an naked eyes, microscope and X-ray fractography etc. It can predict applied load as well as load type. These methods are applicable to components with simple boundary condition but aren't applicable to components with complex boundary condition. The existing fractography don't catch hold of failure boundary condition quantitatively. Especially, in case that the components isn't fractured at same position. We must determine the most dangerous failure boundary condition to evaluate their operation mechanism. The effect of various factors on response should be estimated to solve this statical problem. This study presents the most dangerous failure boundary condition of rocker arm shaft using orthogonal array and ANOVA in order to assure its robustness.

• 대한기계학회논문집A
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• 제25권10호
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• pp.1621-1626
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• 2001

The structural optimization have been carried out in the continuous design space or in the discrete design space. Methods fur discrete variables such as genetic algorithms , are extremely expensive in computational cost. In this research, an iterative optimization algorithm using orthogonal arrays is developed for design in discrete space. An orthogonal array is selected on a discrete des inn space and levels are selected from candidate values. Matrix experiments with the orthogonal array are conducted. New results of matrix experiments are obtained with penalty functions leer constraints. A new design is determined from analysis of means(ANOM). An orthogonal array is defined around the new values and matrix experiments are conducted. The final optimum design is found from iterative process. The suggested algorithm has been applied to various problems such as truss and frame type structures. The results are compared with those from a genetic algorithm and discussed.

• 한국자동차공학회논문집
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• 제10권6호
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• pp.125-132
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• 2002

Bumpers are structural components to reduce physical damage to the front and rear ends of a passenger motor vehicle from low speed collisions. Damage assessment and the protectiveness are the commonly used designing criteria but in this study, relative displacements of the bumper are examined. To absorb the crash energy without significant damage to the bumper itself, foam material is installed between fascia and beam. However, it is not easy to predict the exact displacements generated in bumper structures through FEM because the compressive stress-strain curve of a foam material depends on strain rates that deviates significantly on each trial. Under this uncertain condition, a range of displacements is calculated and the optimum design is performed using the design of experiments. The result will be used to find the design that minimizes the weight within displacement constraints. The orthogonal array of L9 is introduced to find the optimum of the design variables that considers the thickness of inner beam, outer beam and stay, This study will suggest the design procedure of a front bumper using the uncertain stress-strain curve of a foam material.