Lee, Doo Yong

Petri net modeling combined with heuristic search provides a new scheduling method for flexible manufacturing systems. The method formulates a scheduling problem with a Petri net model. Then, it generates and searches a partial reachability graph to find an optimal or near optimal feasible schedule in terms of the firing sequence of the transitions of the Petri net model. The method can handle features such as routing flexibility, shared resources, lot sizes and concurrency. By following the gen

Centralized and distributed automated guided vehicle system (AGVS) models for materials handling, and the model for part processing are integrated into a single coherent model. This formulation can be used to collectively schedule and control the entire flexible manufacturing system (FMS) as opposed to the traditional separate scheduling of part processing and material handling. The two AGVS models are based on Petri nets and can be directly used in the scheduling method that uses Petri nets for

BACKGROUND: The success of a telerobotic surgery system with haptic feedback requires accurate force-tracking and position-tracking capacity of the slave robot. The two-channel force-position control architecture is widely used in teleoperation systems with haptic feedback for its better force-tracking characteristics and superior position-tracking capacity for the maximum stability margin. This control architecture, however, requires force sensors at the end-effector of the slave robot to measu

ABSTRACT This paper proposes a novel method for a real‐time cutting simulation of deformable objects using meshless method. The method utilizes a rapid refinement of topological relations among the simulation nodes of meshless deformable objects. Topological relations are defined as an undirected graph based on a visibility criterion. The graph connects the adjacent nodes that lie within a support of each node. The topological relations are refined by removing the edges of the graph that is inte

A scheduling method that uses Petri net modeling and heuristic search is extended to explicitly handle setup times in flexible manufacturing systems. This method formulates the problem with a Petri net model and applies a search algorithm to the Petri net model. A good heuristic function for the search can be quickly estimated from the Petri net model. The method can handle setup times, routing flexibility, shared resources, concurrency and lot sizes.< <ETX xmlns:mml="http://www.w3.org/1998/Math

Acquisition of the contact force at the instrument tip can enable better performance, e.g. transparency of the haptic feedback in the surgical robot systems. It is, however, difficult to measure the contact force directly due to technical limitations in attaching sensors to the tip of the instruments. This paper proposes a method to estimate the forces by installing the sensors away from the instrument tip. The proposed method employs specially designed mechanical parts of the slave robot, i.e.

The methyl iodide (CH3I) removal performance of tri-ethylene-di-amine impregnated activated carbon (TEDA-AC) used in the air cleaning unit of nuclear power plants (NPPs) should be maintained at least 99% between 24 month-performance test period. In order for evaluating the effectiveness of TEDA-AC on the removal performance of CH3I in nuclear power plant during the operation of NPPs, the long-term test for up to 15 months was carried out under the simulated operating conditions (e.g., 25 °C, RH

BACKGROUND: Colonoscopy simulation has been increasingly applied as a method of training, which can supplement the traditional patient-based training in recent years. However, the current level of realism of the simulation is insufficient. One of the main difficulties degrading the realism is real-time simulation of colon deformation involving multi-contact interaction with the endoscope. METHODS: This paper proposes a novel simulation framework for real-time deformation of the colon and endosco

SUMMARY Previous researches on analysis of stability of haptic simulation largely assume that the virtual environment is passive. But the virtual environment can become non-passive due to various reasons including discretization errors and interaction dynamics between virtual tools and objects. This paper provides an analysis of the stability and performance of the haptic simulation involving non-passive virtual environment. The dynamic interaction between the virtual tools and the objects is mo