• Journal of Korean Society on Water Environment
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• v.25 no.5
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• pp.704-712
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• 2009

Advanced Phase Isolation Ditch (APID) process was studied to develop economic retrofitting technology, for the plants where retrofitting of common activated sludge process is required. In this study, to evaluate and monitor the effluent water quality ($BOD_5$, SS, T-N, and T-P) and operating conditions (Influent, SVI, SRT, and HRT) as process capable and stable parameters for treating municipal wastewater, a demonstration plant was installed and operated in the existing sewage treatment plant of P city. During this study, the average effluent $BOD_5$, SS, T-N, and T-P concentrations were 7.7, 5.6, 10.8, and 1.6 mg/L. Trend analysis of influent $BOD_5$, SS, T-N, and T-P in APID process were illustrated that APID process need for more strong APID process management on the winter session, such as developing new intermediated aeration mode, operating methods, and managements strategy. At the application of control chart, the signal of uncommon effects at APID process was determined much higher existing control chart tntr conventional control chart in this study. These results indicate that conventional control chart has been collected and determined cleary signal at only stable situation. Therefore, newly developed APID process of dynamic control chart can be one of the useful tool for monitoring and management process.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.17 no.30
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• pp.107-116
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• 1994

This paper formulates a dynamic monitoring and control model with a machine state by quality variations in a single lot production system. A monitoring model is based on estimate of machine state obtained using control theory. The model studied in this paper has a great advance from a point of view the combination between quality control (Sampling, Control Chart) and automatic control theory, and can be extended in a several ways.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.2
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• pp.502-511
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• 1994

A video deck mechanism is composed of various cams, links, and gears, and it requires precise movement. So kinematic motion between parts should be considered to get desired movement depending on the timing chart which defines movement of each part to get desired mode. Also dynamic effects should be considered to get right tape tension and to estimate motor force required to obtain accurate motion. The design process of the deck mechanism of VCR is explained briefly. The loading block of the deck mechanism is divided into a tape translational group and a brake control group. Each group is modeled for kinematic and dynamic analysis. Finally, two groups are combined together to analyze the loading block of the deck mechanism. Results are used to understand and modify an existing design.

• Journal of Drive and Control
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• v.20 no.1
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• pp.27-33
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• 2023

From the perspective of dental chair manufacturers, it is important to of localizing hydraulic system in order to secure market competitiveness. This study aims to develop the analysis model of a dental chair which overseas companies secure core technologies. The study follows the steps below. First, the component parts of the solenoid valve unit of a foreign leading company are analyzed and implemented in virtual environment. Second, dynamic behavior scenario is established based on solenoid valve signal chart provided by a foreign leading company. The analysis model is verified and its performance is analyzed using dynamic behavior according to each scenario. Third, a simulation is carried out to determine whether the cylinder velocity of designed hydraulic system surpasses 1cm/s as required by the design.

• Journal of Ocean Engineering and Technology
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• v.13 no.3B
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• pp.106-115
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• 1999

Modeling a discrete event system such as a sequential control system is difficult compared with a continuous system. Petri nets have been introduced as an analyzing and design tool for the discrete systems. One of the problems in its applications is that the model can not be analyzed easily in the case of large scale or complicated systems because of increase of the number of components of the system. To overcome this problem, some methods for dividing or reducing Petri nets have been suggested. In this paper, an approach for a hierarchical expression of Petri nets based on Sequential Function Chart(SFC) is proposed. A measuring tank system will be described as a typical kind of discrete systems. The system is modeled by sub Petri nets based on SFC in order to analyze and visualize efficiently about the dynamic behaviors of the system. Some numerical simulations using state equations are performed to prove the validity of the proposed method.

• The Korean Journal of Applied Statistics
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• v.22 no.6
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• pp.1191-1201
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• 2009

The cumulative sum(CUSUM) control charts are typically used for detecting small level shifts in process control. To control an auto-correlated process, the model-based control methods can be employed, in which the residuals from fitting a time series model are applied to the CUSUM chart. However, the persistent level shifts in the original process may lead to varying mean shifts in residuals, which may deteriorate detection performance significantly. Therefore, in this paper, focussing on ARMA(1,1), we propose a new CUSUM type control method which can detect the dynamic mean shifts in residuals especially with oscillating pattern effectively and, through the simulation study, evaluate its performance by comparing with other various CUSUM type control methods introduced so far.

• Journal of Korean Institute of Industrial Engineers
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• v.32 no.3
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• pp.210-218
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• 2006

Traditional statistical process control (SPC) applied to discrete part industry in the form of control charts can look for and eliminate assignable causes by process monitoring. On the other hand, engineering process control (EPC) applied to the process industry in the form of feedback control can maintain the process output on the target by continual adjustment of input variable. This study presents controlling and monitoring rules adopted by variable sampling interval (VSI) to change sampling intervals in a predetermined fashion on the predicted process levels under integrated EPC and SPC systems. Twelve rules classified by EPC schemes(MMSE, constrained PI, bounded or deadband adjustment policy) and type of sampling interval combined with EWMA chart of SPC are proposed under IMA (1,1) disturbance model and zero-order (responsive) dynamic system. Properties of twelve control rules under three patterns of process change (sudden shift, drift and random shift) are evaluated and discussed through simulation and control rules for integrated VSI EPC and SPC systems are recommended.

• Structural Engineering and Mechanics
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• v.81 no.5
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• pp.647-664
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• 2022

The powerful data mapping capability of computational deep learning methods has been recently explored in academic works to develop strategies for structural health monitoring through appropriate characterization of dynamic responses. In many cases, these studies concern laboratory prototypes and finite element models to validate the proposed methodologies. Therefore, the present work aims to investigate the capability of a deep learning algorithm called Sparse Autoencoder (SAE) specifically focused on detecting structural alterations in real-case studies. The idea is to characterize the dynamic responses via SAE models and, subsequently, to detect the onset of abnormal behavior through the Shewhart T control chart, calculated with SAE extracted features. The anomaly detection approach is exemplified using data from the Z24 bridge, a classical benchmark, and data from the continuous monitoring of the San Vittore bell-tower, Italy. In both cases, the influence of temperature is also evaluated. The proposed approach achieved good performance, detecting structural changes even under temperature variations.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2005.05a
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• pp.723-729
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• 2005

Traditional statistical process control(SPC) applied to discrete part industry in the form of control charts can look for and eliminate assignable causes by process monitoring. On the other hand, engineering process control(EPC) applied to the process industry in the form of feedback control can maintain the process output on the target by continual adjustment of input variable. This study presents controlling and monitoring rules adopted variable sampling interval(VSI) to change sampling intervals in a predetermined fashion on the predicted process levels for integrated EPC and SPC systems. Twelve rules classified by EPC schemes(MMSE, constrained PI, bounded or deadband adjustment policy) and type of sampling interval combined with EWMA chart of SPC are proposed under IMA(1,1) disturbance model and zero-order (responsive) dynamic system. The properties of twelve control rules under three patterns of process change(sudden shift, drift and random shift) are evaluated and discussed through simulation and control rules for integrated VSI EPC and SPC systems are recommended.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.6
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• pp.1861-1871
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• 1991

In this study, the piping system conveying unsteady flow is considered. The effects of coupling between the pipe motion and the velocity and pressure of fluid are included for the dynamic stability and response analysis of the piping system. The dynamic equations for a piping system are derived by Newtonian dynamics. For the momentum and continuity equations, the concept of moving control volume is applied. Thus, the governing equations derived herein are valid for the applications to the vibration problems occurred when a piping system starts up or shuts down and also when the valves and pumps operate. For a simply supported straight pipe, the stability analysis is conducted for various nondimensional parameters. The dynamic responses, in both stable and unstable region of stability chart, are numerically tested by the use of central difference method.