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Estimation Force of Master-Slave for the End Effector of Hydraulic Servo System Using SMCSPO
Karam Dad Kallu,Saad Jamshed Abbasi,Min Cheol Lee 제어로봇시스템학회 2017 제어로봇시스템학회 국제학술대회 논문집 Vol.2017 No.10
In this research a bilateral control method is proposed to find the estimation force of master-slave at the end effector of hydraulic servo system using sliding mode control with sliding perturbation observer (SMCSPO). The sliding perturbation observer (SPO) estimates the reaction force at the end effector of master and slave without using any sensor. Sliding mode control (SMC) is used as bilateral controller for the robust position tracking and control of slave device. A bilateral control strategy in hydraulic servo system provides robust position and force tracking between master and slave. This research experimentally verifies that the slave device can follow the trajectory of the master device using the proposed bilateral control strategy and reaction force estimation method.
Karam Eliker,Wei Dong Zhang 제어·로봇·시스템학회 2020 International Journal of Control, Automation, and Vol.18 No.2
This paper presents a reliable and novel quadrotor flight control system designed to enhance trajectory tracking performance, robustness and adaptiveness against the uncertain parameters and the external wind disturbance. By combining a recursive control methodology with a robust control algorithm, a finite-time adaptive integral backstepping fast terminal sliding mode control is designed for major control loops related to position tracking and attitude stabilization. To estimate quadrotor mass and inertia moments, only four adaptation laws are developed. To compensate the unknown upper bound on the disturbances, a robust and adaptive switching gain is designed. The designed controller guarantees that all the closed signals are semi-global practical finite-time stability while the tracking error converges to a small neighborhood of the origin. The obtained numerical results and comparison studies show the effectiveness, robustness, adaptiveness and energy efficiency of the proposed flight control system.
Atomic Layer Deposition of TiO₂ using Titanium Isopropoxide and H₂O
Karam Cho,Jung-Dong Park,Changhwan Shin 대한전자공학회 2016 Journal of semiconductor technology and science Vol.16 No.3
Titanium dioxide (TiO₂) films are deposited by atomic layer deposition (ALD) using titanium isopropoxide (TTIP) and H₂O as precursors. The operating instructions for the ALD equipment are described in detail, along with the settings for relevant parameters. The thickness of the TiO₂ film is measured, and thereby, the deposition rate is quantitatively estimated to verify the linearity of the deposition rate.
Karam Dad Kallu,Wang Jie,이민철 제어·로봇·시스템학회 2018 International Journal of Control, Automation, and Vol.16 No.3
We estimated the reaction force for assembly work with a three-link dual-arm robot manipulator using sliding mode control with a sliding perturbation observer (SMCSPO) without using a force sensor. The sliding perturbation observer (SPO) is used to estimate the reaction force of the end effector without using any sensor. The SPO estimates the perturbation, which consists of the parameter uncertainties, nonlinear terms, and disturbances such as the reaction force. During assembly, the most effective perturbation term is close to the reaction force, so we assumed that the estimated perturbation is the same as the reaction force. The estimated perturbation was compared with the reaction force from the dynamics of the manipulator using a simulation with the SimMechanics toolbox of MATLAB/SIMULINK. The simulation results show the performance of the SMCSPO and that the reaction force can be estimated using the SPO without any sensor. The method can improve the structural reduction of link manipulator robots and decrease costs.
Karam Mahmoud,Puneet Anand,Ehab El-Salakawy 사단법인 한국계산역학회 2018 Computers and Concrete, An International Journal Vol.21 No.6
A non-linear finite element model (FEM) was constructed using a three-dimensional software (ATENA-3D) to investigate the effect of strengthening on the behavior of prestressed hollow-core (PHC) slabs with or without openings. The slabs were strengthened using near surface mounted (NSM)-carbon fiber reinforced polymer (CFRP) strips. The constructed model was validated against experimental results that were previously reported by the authors. The validated FEM was then used to conduct an extensive parametric study to examine the influence of prestressing reinforcement ratio, compressive strength of concrete and strengthening reinforcement ratio on the behavior of such slabs. The FEM results showed good agreement with the experimental results where it captured the cracking, yielding, and ultimate loads as well as the mid-span deflection with a reasonable accuracy. Also, an overall enhancement in the structural performance of these slabs was achieved with an increase in prestressing reinforcement ratio, compressive strength of concrete, external reinforcement ratio. The presence of openings with different dimensions along the flexural or shear spans reduced significantly the capacity of the PHC slabs. However, strengthening these slabs with 2 and 4 (64 and 128 mm2 that represent reinforcement ratios of 0.046 and 0.092%) CFRP strips was successful in restoring the original strength of the slab and enhancing post-cracking stiffness and load carrying capacity.
Karam Kang,Kwang Yoon Jung,Doh Young Lee,Jae Hyung Kim,Hye Min Han,ln Hak Choi,Seung-Kuk Baek,Hyunjung Kim 대한연하장애학회 2018 대한연하장애학회지 Vol.8 No.1
Objective: Pharyngoesophageal stricture formation and dysphagia following total laryngectomy negatively affect quality of life and result in nutritional compromise that can be successfully managed with various techniques. This study was conducted to describe our experiences of office-based balloon dilatation by transnasal endoscopy, which can be performed by an otolaryngologist. Method: The present study investigated three patients who underwent transnasal endoscopy guided balloon dilatation of pharyngoesophageal stricture. The assessment was performed based on the number of procedures and recurrences, final subjective outcomes, and complications. Result: There were no post-procedural complications. In one patient, a scarric band was found after the procedure; therefore, steroids were injected into the stricture site. There were 2–3 balloon dilatations and the interval between dilatations was 3–6 months. All patients were able to tolerate solid diet after 2 or 3 sessions. Conclusion: Transnasal endoscopic balloon dilatation, which can be easily performed by an otolaryngologist in an office setting without sedation or general anesthesia, can be a useful modality for treating pharyngoesophageal stricture after total laryngectomy. (
Information uncertainty, market sentiment, and analyst reports
Karam Kim,Doojin Ryu,Heejin Yang 한국재무학회 2020 한국재무학회 학술대회 Vol.2020 No.11
This study examines the effects of investor sentiment and information uncertainty on the stock market response to analyst recommendation changes within a unified framework. Recent progress in the field of behavioral finance suggests that sentiment affects the classical relationship between analyst recommendations and stock return dynamics. Our novel findings suggest that the degree of information uncertainty should be considered when investigating the effect of sentiment. Although investor sentiment significantly explains the observed stock market reactions to analyst recommendation changes under high information uncertainty, it loses its explanatory power under low information uncertainty. Furthermore, analyst recommendations convey significant trading indications if information uncertainty is high, but they are less informative if information uncertainty is low.