• Journal of the Korean earth science society
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• v.27 no.6
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• pp.620-642
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• 2006

The Moho structure and its deformation in the southern part of the Korean Peninsula were estimated using gravity and topography data. Gravity signals from the upper and lower crust were separated using a filter that was computed from isostacy and elastic thickness. The result of this study shows three characteristic features of the Moho deformation. First, the Moho folding structure is parallel to SKTL (the South Korean Tectonic Line), which indicates positive association with the collision of the Yeongnam and Gyeonggi Massifs and repeated compression afterwards. In contrast, noticeable deformation of the Moho was not observed along the Imjingang Belt, which is interpreted as another continental collisional belt in the Korean Peninsula. Second, the Moho beneath the Gyeongsang Basin has remarkably risen; this seems to be the result from both the collisional compression and buoyancy caused by magmatic underplating. Third, the Moho deformation is shallowest in the east of the Taebaek Mountains and deepens toward the west, consistent with the topographic characteristic of the Korean Peninsula of "high east and low west". It can be interpreted as the results of the opening of the East Sea and Ulleung Basin. A tectonic explanation for this could be the ascent of the mantle induced by continental rifting and horizontal extension at the early stage of the opening of the East Sea. The Moho deformation model computed in this study correlates well with the earthquake distribution and crustal movement measured by GPS. We suggest that the compression along the SKTL is still exerted, consequently, the Moho deformation is active, although it may be weak.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.6
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• pp.3013-3022
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• 2013

Satisfying the large car impact condition of the high level SB5-B for "SMART Highway" longitudinal barriers, the possibility of increase of the small car impact velocity from 120km/h to 130km/h was investigated. Through computer simulation using input parameters calibrated to full-scale crash test results, various longitudinal semi-rigid barrier models were improved such that for the small car impact speed of 120km/h the change of longitudinal and transverse velocities of the impact vehicle can satisfy the THIV limit. The barrier model determined through this process satisfied the performance assessment criteria for SB5-B impact conditions. Varying the wing angle of slip block-outs of the passed barrier model, the possibility of increase of the small car impact velocity was investigated by FEA and a full-scale crash test was conducted. It has been shown that the possibility to increase the small car impact speed to 130km/h is high if the test facility condition for 130km/h impact velocity is better equipped.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.7
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• pp.611-619
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• 2016

This paper proposes a collision prevention system for an agricultural unmanned helicopter. The collision prevention system consists of an obstacle detection system, a mapping algorithm, and a collision avoidance algorithm. The obstacle detection system based on a LiDAR sensor is implemented in the unmanned helicopter and acquires distance information of obstacles in real-time. Then, an obstacle mapping is carried out by combining the distance to the obstacles with attitude/location data of the unmanned helicopter. In order to prevent a collision, alert is activated to an operator based on the map when the vehicle approaches to the obstacles. Moreover, the developed collision prevention system is verified through flight test simulating a flight pattern aerial spraying.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2019.11a
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• pp.269-269
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• 2019

The ships are turning for the purpose of collision avoidence and change of course. It is possible that ships have capsizing accident when improper loading of cargo and excessive use rudder angle in turning. It is difficult for navigation officers to recognize the danger of heeling during a turn, because the dynamic state of the ship changes in real time. Thus, in this study, ship's heeling angle was predicted during turning using the maneuverability indices estimated from the ship's autopilot. The maneuverability indices estimated through the Kalman filter of Autopilot is real-time predictable. The turning radius was obtained from the estimated Index of turining ability and calculations of the heeling angle were possible in turning. It is intended to be used as a basic data on the prevention of danger heeling angle during turning.

• Journal of Auto-vehicle Safety Association
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• v.5 no.1
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• pp.44-49
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• 2013

This paper presents a lateral collision risk index between an ego vehicle and a rear-side vehicle. The lateral collision risk is designed to represent a lateral collision risk and provide the appropriate threshold value of activation of the lateral collision management system such as the Blind Spot Detection(BSD). The lateral collision risk index is designed using the Time to Line Crossing(TLC) and the longitudinal collision index at the predicted TLC. TLC and the longitudinal collision index are calculated with the signals from the exterior sensor such as the radar equipped on the rear-side of a vehicle and a vision sensor which detects the distance and time to the lane departure. For the robust situation assessment, the perception of driving environment determining whether the road is straighten or curved should be determined. The relative motion estimation method has been proposed with the road information via the integrated estimator using the environment sensors and vehicle sensor. A lateral collision risk index was composed with the estimated relative motion considering the relative yaw angle. The performance of the proposed lateral collision risk index is investigated via computer simulations conducted using the vehicle dynamics software CARSIM and Matlab/Simulink.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.5
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• pp.497-503
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• 2018

Passenger ships and training ships have a common feature in that they serve many passengers. Thus, safe navigation is very important. During normal sailing, a ship may turn using various types of steering, including maneuvers to avoid collisions with dangerous target. When a ship turns, a heeling angle occurs. If trouble arises during sailing, a dangerous heeling angle may result or a capsizing accident. In this study, the heeling angle during turning was measured through experimentation with two training ships similar to passenger ships. These findings were compared with theoretical formulas for heeling angle when turning. We confirmed that the limit of the maximum heeling angle estimation using heeling angle formula when turning presented in IMO stability criteria. In addition, it was confirmed that the maximum estimated heeling angle can be reached by applying the result calculated in the theoretical formula 1.4 times when turning right and 1.1 times when turning left to reflect sailing speed when of rudder hard over. It is expected that this study will provide basis data for establishing safe operation standards for the prevention of dangerous heeling angles when turning.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.5
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• pp.499-506
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• 2011

In this study, the performance of composite safety barriers was evaluated through computer simulation. A composite safety barrier of SB4 grade was modeled. The MAT58 material model provided by LS-DYNA software was used to model composite material. The performance of composite material varies according to fiber, resin type, and fiber direction. Polyurethane resin and glass fiber were used. The performance of three different stacking designs was evaluated by carrying out vehicle impact simulation. The performance evaluation based on the vehicle crash manual includes the structural strength performance, the passenger protection performance, the vehicle behavior after crash, scattering of the guardrail. As the result of the finite element analysis, the barrier composed of the more transverse direction fibers shows the better performance on the impact simulation.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.838-843
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• 2008

Since thickness deformation and lateral deflection often occurs during the collision of flexible bodies, they should be considered simultaneously in the impact analysis. The thickness deformation, however, cannot be considered in beam/shell theory since the thickness is assumed to be constant in the theory. So, solid elements are employed to estimate the thickness deformation. However, the CPU time increases significantly if solid elements are employed. In the present study, a modeling method for the impact analysis of a flexible body employing Hertzian contact theory is presented. The efficiency and the accuracy of the modeling method are discussed with some numerical examples.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2002.10a
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• pp.206-211
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• 2002

FPSO(FSO)같은 대형 구조물을 육상에서 건조하여 LOAD-OUT 과 FLOAT-OFF 를 수행하기 위해 한 척의 반 잠수바지로는 불가능하였다. 그래서 두 척의 반 잠수 식 바지를 HINGED TYPE 이 아닌 FIXED TYEP 으로 연결하였고 이에 따라 FLOAT OFF 시에 고려하여야 할 사항 중에서 횡강도 및 바지가 잠수 할 시점의 STABILITY 가 중요시되었다. 또한 FSO 가 잠수바지로부터 떨어져 나올 시점에서, STABILITY CASING 과 FSO 와의 충돌가능성도 고려하여야 할 사항이다. 이 논문에서는 안정성 측면에서의 반 잠수식 바지의 BALLASTING과 충돌방지 차원에서 전체적인 OPERATION에 대하여 언급하였다.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2002.10a
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• pp.124-128
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• 2002

본 논문에서는 FPSO 측면에 나란히 연결된 작업선에 대한 계류계 해석이 수행되었다. FPSO 측면에 연결된 작업선의 횡동요에 의한 충돌 가능성, 작업선의 연결선 및 펜더의 파손 가능성 등에 대한 검토가 이루어졌다. 다물체 계류계 해석을 위하여 MOSES 프로그램을 사용하였고, FPSO와 작업선과의 유체역학적 상호작용은 무시하였다.