• 정보보호학회논문지
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• 제32권4호
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• pp.617-628
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• 2022

Ascon은 2015년부터 진행되고 있는 NIST 경량암호 공모사업의 최종 라운드 후보 중 하나이며, 해시 모드 Ascon-Hash와 Ascon-Xof를 지원한다. 본 논문에서는 Ascon-Hash의 충돌 공격을 위한 MILP 모델을 개발하고, 해당 모델을 통해 양자 컴퓨팅 환경에서 활용 가능한 차분 경로를 탐색한다. 또한, 탐색한 차분 경로를 이용하여 양자 컴퓨터를 사용할 수 있는 공격자가 3-라운드 Ascon-Hash의 양자 free-start 충돌쌍을 찾을 수 있는 알고리즘을 제시한다. 본 공격은 Ascon-Hash에 대한 충돌 공격을 양자 컴퓨팅 환경에서 최초로 분석했다는 점에서 유의미하다.

• 로봇학회논문지
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• 제12권3호
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• pp.258-262
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• 2017

In this paper, we propose a new collision detection algorithm for human-robot collaboration. We use an IMU sensor located at the tip of the manipulator and the kinematic behavior of the manipulator to detect the unexpected collision between the robotic manipulator and environment. Unlike other method, the developed algorithm uses only the kinematic relationship between the manipulator joint and the end effector. Therefore, the collision estimation signal is not affected by the error of the dynamics model. The proposed collision detection algorithm detects the collision by comparing the estimated acceleration of the end effector derived from the position, velocity and acceleration trajectories of the robot joints with the actual acceleration measured by the sensor. In simulation, we compare the performance of our method with the conventional Residual Observer (ROB). Our method is less sensitive to the load variation because of the independency on the dynamic modeling of the manipulator.

• 로봇학회논문지
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• 제15권2호
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• pp.169-176
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• 2020

This paper studied the collision detection of robot manipulators for safe collaboration in human-robot interaction. Based on sensor-based collision detection, external torque is detached from subtracting robot dynamics. To detect collision using joint torque sensor data, a comparative study was conducted using data-based machine learning algorithm. Data was collected from the actual 3 degree-of-freedom (DOF) robot manipulator, and the data was labeled by threshold and handwork. Using support vector machine (SVM), decision tree and k-nearest neighbors KNN method, we derive the optimal parameters of each algorithm and compare the collision classification performance. The simulation results are analyzed for each method, and we confirmed that by an optimal collision status detection model with high prediction accuracy.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2019년도 학술발표회
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• pp.267-267
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• 2019

Driftwood is one of serious problems in a river environment. In several countries, such as Indonesia, Japan, and Italy, the driftwood frequently appears in a river basin, and it can alter the channel bed, flow configuration by wood deposition and jam formation. Therefore, the studies related to driftwood have been actively conducted by many researchers to understand the mechanism of driftwood dynamics. In particular, wood motion by collision is one of the difficult issues in the numerical simulation because the calculation for wood collision requires significantly expensive calculation time due to small time step. Thus, this study conducted the numerical simulation in consideration of the wood motion by water flow and wood collision to understand the wood dynamics in terms of computation. We used the 2D (two-dimensional) depth-averaged velocity model, Nays2DH, which is a Eulerian model to calculate the water flow on the generalized coordinate. A Lagrangian type driftwood model, which expresses the driftwood as connected sphere shape particles, was employed to Nays2DH. In addition, the present study considered root wad effect by using larger diameter for a particle at a head of driftwood. An anisotropic bed friction was considered for the sliding motion dependent on stemwise, streamwise and motion directions. We particularly considered changeable draft at each particle and projection area by an angle between stemwise and flow directions to precisely reproduce the wood motions. The simulation results were compared with experimental results to verify the model. As a result, the simulation results showed good agreement with experimental results. Through this study, it would be expected that this model is a useful tool to predict the driftwood effect in the river flow.

• 대한인간공학회지
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• 제30권1호
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• pp.137-150
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• 2011

Nationally and internationally reported statistics on marine accidents show that 80% or more of all marine accidents are caused fully or in part by human error. According to the statistics of marine accident causes from Korean Maritime Safety Tribunal(KMST), operating errors are implicated in 78.7% of all marine accidents that occurred from 2002 to 2006. In the case of the collision accidents, about 95% of all collision accidents are caused by operating errors, and those human error related collision accidents are mostly caused by failure of maintaining proper lookout and breach of the regulations for preventing collision. One way of reducing the probability of occurrence of the human error related marine accidents effectively is by investigating and understanding the role of the human elements in accident causation. In this paper, causal factors/root causes classification systems for marine accident investigation were reviewed and some typical human error analysis methods used in shipping industry were described in detail. This paper also proposed a human error analysis method that contains a cognitive process model, a human error analysis technique(Maritime HFACS) and a marine accident causal chains, and then its application to the actual marine accident was provided as a case study in order to demonstrate the framework of the method.

• 한국항해항만학회지
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• 제28권1호
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• pp.9-16
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• 2004

본 연구는 선박충돌회피 알고리즘에 대하여 검토하고, 이를 개선하려는 의도로 수행되었다. 선박충돌회피 알고리즘에 대한 연구는 지금까지 많이 수행되었는데, 이런 연구에서 채용하고 있는 핵심 이론을 내용에 따라 구분하면 위험도계산법과 위험지역 설정법으로 각각 나뉠 수 있다. 그 두 가지 이론은 각각의 장점과 단점을 가지고 있으며, 또한 그 한계성을 포함하고 있다. 이번 연구는 두 가지 이론의 한계점을 극복하기 위한 방안을 제시한다. 제시된 모델은 위험도 계산법을 기초로 하고 있으며, 위험도계산법에서 가장 문제시 되어온 임계값 설정 문제를 해결하기 위하여, 사용자가 항해 환경 등에 따라 적절히 그 설정값을 선택할 수 있는 기능을 제시하고 있다. 또한 두 가지 이론의 상호 관계를 규명하기 위해서 위험도 계산법의 시뮬레이션을 인용하여, 본선 주위에 위험구역을 도식해 봄으로써, 위험지역설정과 그 차이를 비교하여, 양자간의 이해를 돕는 수단으로 활용하였다. 마지막으로 위험도 계산법의 경우, 특히 TCPA, DCPA를 사용하여 위험도계산을 할 경우, 두 선박이 선미에서 너무 접근하는 문제점이 발생하는데, 이런 문제의 해결책의 하나로, 위험지역 설정법을 부분적으로 적용한 새로운 모델을 제시하고 그 효용성을 검증하였다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2006년도 추계학술대회 논문집
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• pp.1203-1209
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• 2006

One dimensional collision analysis is often used to simulate a train-to-train coupling or collision accident. But there are various numerical modeling techniques utilized for dynamic models of rolling stocks such as a lumped-spring-mass model or a bar-mass model. In rolling stock industries, a lumped-spring-mass model is mainly applied without consideration of bogie attachments separately. In this case, a dynamic stiffness coefficient is introduced to compensate the overestimated car mass effects due to the linkage stiffness of bogies and seats. In this paper, the effects of dynamic stiffness coefficients and wheel-rail friction coefficients were studied by simulating a bar-mass model with bogie attachments separately.

• 한국항공운항학회지
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• 제14권1호
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• pp.49-54
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• 2006

The purpose of RVSM is to reduce vertical separation minima for aircrafts which operate between FL290- FL410 inclusive in regional airspace, and to increase airspace capacity by providing additional flight levels. In order to introduce RVSM, it is necessary to estimate quantitatively airborne collision risk due to the reduction in vertical separation minimum. In this study, the basic concept of RVSM safety assessment and Reich collision risk model are introduced and mid-air collision risk in Incheon FIR is estimated based on ICAO RVSM safety assessment technique and Reich Model.

• 한국군사과학기술학회지
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• 제15권3호
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• pp.266-271
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• 2012

The rescue methods for the marine casualties are limited due to the characteristics of operation environment of the vessel. Especially the most of marine accidents have been occurred at the bow structure of ship. Moreover the failure of bow structure may lead to catastrophic mishaps. In this paper, the extents of damage of a bow structure fracture subject to collision accident was investigated by using numerical method. The computer simulation approach by using Finite Element Method was employed to accomplish this goal. A finite element model, a 3D model of ship, has been utilized to evaluate damage of bow structure according to collision scenario. In conclusion, we have demonstrated that the plastic deformation occurred at the bow structure. Also it was shown that the collision angle clearly plays a role in determining amount of damage of ship structures.

• 한국해양공학회지
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• 제9권1호
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• pp.22-35
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• 1995

A simplified numerical procedure have proposed to trace the dynamic behaviour of offshore tubulars subjected to lateral collision impacts. The local denting and overall bending deformation of the struck tubular are represented by a non-linear spring and an elastic visco-plastic beam respectively. In this method a temporal finite difference method and a spacial finite element method are employed. Using this method various boundary conditions are able to considered and their effects on the extent of damage can be quantified. The extent of damage due to collision can be obtained as results of the dynamic analysis. The predictions using the proposed method have been correlated with existing test results and then the reliability of the procedure has been substantiated. The characteristics of the dynamic response of tubulars under lateral impacts are compared for simply supported roller and fixed end conditions and their effects on the extent of damage are specfied.