Intralogistics is a technology that optimizes, integrates, automates, and manages the logistics flow of goods within a logistics transportation and sortation center. As the demand for parcel transportation increases, many sortation systems have been developed. In general, the goal of sortation systems is to route (or sort) parcels correctly and quickly. We design an n-grid sortation system that can be flexibly deployed and used at intralogistics warehouse and develop a collaborative multi-agent reinforcement learning (RL) algorithm to control the behavior of emitters or sorters in the system. We present two types of RL agents, emission agents and routing agents, and they are trained to achieve the given sortation goals together. For the verification of the proposed system and algorithm, we implement them in a full-fledged cyber-physical system simulator and describe the RL agents’ learning performance. From the learning results, we present that the well-trained collaborative RL agents can optimize their performance effectively. In particular, the routing agents finally learn to route the parcels through their optimal paths, while the emission agents finally learn to balance the inflow and outflow of parcels.
The purpose of this study was to evaluate the consistency of two electronic apex locators in vitro model.Materials consisted of fifty two extracted premolars and two electronic apex locators; Root ZX (J. Morita, Osaka, Japan) and E-Magic Finder Deluxe (S-Denti, Cheonan, Korea). After access preparation, the teeth were embedded in a saline-mixed alginate model. Canal lengths of each tooth were measured at "0.5"and "Apex"mark of the apex locators, respectively so that each tooth had two measurements from 0.5 and Apex points. The file was fixed at final measurement using a glass ionomer cement. The apical 4 ㎜ from the apex was exposed to measure the distance from the file tip to the major apical foramen of each tooth. Average distances and standard deviations were used to evaluate the consistency.Results showed that all measurements of both Root ZX and E-Magic Finder located the major foramen the range of ± 0.5 ㎜ level. Both apex locators showed better consistency at Apex mark than at 0.5 mark. The average distance of file tip-major foramen was -0.18 ㎜ at 0.5 mark and -0.07 ㎜ at Apex mark in Root ZX, -0.25 ㎜ at 0.5 mark and -0.02 ㎜ at Apex mark in E-Magic Finder. Standard deviation was 0.21 at 0.5 mark and 0.12 at Apex mark in Root ZX, 0.12 at 0.5 mark and 0.09 at Apex mark in E-Magic Finder. [J Kor Acad Cons Dent 33(1):20-27, 2008]
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