• Transactions of the Korean Society of Automotive Engineers
• /
• v.6 no.2
• /
• pp.178-190
• /
• 1998

We have developed a planar impact model with a capability of reverse calculation to reconstruct various types of automobile collisions. This topic is the main part of what is referred to as accident reconstruction. The model uses the principle of impulse and momentum, and introduces a restitution coefficient and an impulse ratio at the impact center. Based on the car-to-car collision test results, we present how to estimate the restitution coefficient and the impulse ratio from some impact conditions. To validate the model and improve its reliability in accident analysis, the collision analysis has been performer with the estimated parameters. The analysis and experimental results agree well in the kinetic energy loss and the post-impact velocity.

• Journal of Korean Society of Transportation
• /
• v.18 no.4
• /
• pp.107-115
• /
• 2000

We suggest a method which solves the planar, two vehicle collision reconstruction problem. The method based on the Principle of impulse and momentum determines the pre-impact velocity components from Post-impact velocity components, vehicle Physical data and collision geometry. A novel feature is that although the impact coefficients such as the restitution coefficient and the impulse ratio are unknown, the method can estimate automatically the coefficients and calculate the pre-impact velocity components. This reverse calculation is important for vehicle accident reconstruction, since the pre-impact velocities are unknown and Post-impact Phase is the starting Point in a usual collision analysis. However. an inverse solution is not always Possible with the analytical rigid-body impact model. Mathematically, one does not exist under the common velocity condition. On the other hand, our method has a capability of reverse calculation under the condition if the absorbed energy during the collision process can be estimated using the crush profile. To validate the developed collision reconstruction a1gorithm, we use car-to-car collision test results. The analysis and experimental results agree well in the impact coefficients and the Pre-impact velocity components.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.17 no.2
• /
• pp.125-135
• /
• 2001

교합조정이나 대부분의 보철치료는 비가역적이어서 명확한 치료 계획이 없이는 섣불리 치료를 시작하지 말아야 한다. 명확한 치료 계획을 위해서는 증상의 원인 인자를 파악해야 하나, 때때로 그 원인이 불분명하여 환자에게 무어라 설명해야 할지 난감한 경우가 많은 것이 바로 이 분야이다. 교합 재구성을 함에 있어서 생체 역학과 근육의 활동량을 고려해야 하는 것은 이미 주지하고 있는 바이다. 즉, 악관절이나 치아에 대한 하중을 조절함으로써 근조직의 안정을 도모하여 적정한 하악위와 원활한 하악운동을 획득하는 것이 교합 재구성의 큰 목적 중 하나이다.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.2 no.2
• /
• pp.1-11
• /
• 1994

The most commonplace of collisions that directly affect people is that of vehicles. Safety studies have noted a correlation between vehicle occupant injury severity and velocity changes. Methods for estimating collision velocity changes are discussed here. This topic is part of what is referred to as accident reconstruction. Only planar collisions are considered. When a vehicle collides with another, impact dynamics with friction should be considered. This paper presents a general analysis methodology of impact. must dynamics incorporating friction. The presence of friction between sliding contacts during the impact makes the problem difficult since the events such as reverse sliding or sticking, which may occur at different times throughout the impact, must be determined. This paper uses the results of RICSAC experiments for verifying the developed methodology. The analysis and experimental results agree well.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2002.05a
• /
• pp.353-356
• /
• 2002

In vehicle accidents, the rolling, pitching, and yawing which are produced by collisions affect the motions of vehicle. Therefore, vehicle behavior under impact situation should be analyzed in three-dimension. In this study, three-dimensional vehicle dynamic equations based on impulse-momentum conservation principles under vehicle impact are introduced for simulation. This analysis has been performed by the real vehicle impact data from JARI and RICSAC. This study suggested each system modeling such as suspension, steering, brake and tire as well as the appropriate vehicle behavior simulation model with respect to pre and post impact.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.20 no.5
• /
• pp.1486-1497
• /
• 1996

The problem of determining the 3-demensional motion of any two rough bodies after a collision involves some rather long analysis and yet in some points it differs essentially from the corresponding problem in tdwo dimensions. We consider a special problem where two rough ellipsolids moving in any manner collide, and analyze the three dimensional impact process with Coulomb friction and Poisson's hypothesis. The differential equations that describe that process of the impact induce a flow in the tangent velocity space, the flow patterns characterize the possible impact cases. By using the graphic method in impulse space and numerical integration thchnique, we analyzed the impact process inall the possible cases and presented the algorithm for determining the post-impact motion. The principles could be applied to the general problem in three dimensions. We verified the effectiveness of the analysis results by simulating the numerous significant examples.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.26 no.4
• /
• pp.477-482
• /
• 2010

In a case of multiple posterior teeth loss, antagonistic teeth extrude to the edentulous space and compensatory occlusion on the remained anterior teeth leads to occlusal trauma. Extrusion of antagonistic teeth breaks down occlusion plane and loss of posterior support bring about severe wear of remained teeth. In this situation, it is needed to restore remained teeth and edentulous space by increasing vertical dimension to obtain prosthodontic rehabilitation space and to correct occlusion plane. In this case report, the patient had a masticatory problem with loss of posterior teeth support and an esthetic problem of shortened anterior teeth. Before the tooth preparation for the prosthodontic restoration, the patient used removable device for 2 months to increase vertical dimension reversibly. After that, he got provisional fixed restoration with irreversible tooth reduction and used it for 3 months. It had spent 5 month to evaluate the adaptation state on final restoration with incresed vertical dimension. The increasing amount was 3 mm, which was relatively in less degree and masticatory system adapted to the increased vertical dimension without any pathologic changes. Final restoration was made to have equal-intensity contacts on all teeth in a verifiable centric relations and immediate disclusion of all posterior contacts the moment the mandible moves in any direction from centric relation. In addition, metal occlusion surface on posterior teeth was applied to prevent excessive muscle activation, occlusal trauma and the porcelain fracture.