• Journal of the Korean Society of Manufacturing Process Engineers
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• v.2 no.1
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• pp.92-99
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• 2003

Bevel gears are important mechanical parts to transmit power in transportation system high precision parts like bevel gears might be manufactured by closed die forging process for dimensional accuracy. Closed die forging of bevel gears offers the high quality and good mechanical properties and also leads to considerable cost saving. To determinate the proper closed-die forging process for bevel gear forms, three-dimensional finite element simulation for the progressive forging process was earned out and also the simulation results were compared with experimental results.

• 제어로봇시스템학회:학술대회논문집
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• 1994.10a
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• pp.140-145
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• 1994

In this paper, we consider a problem to estimate process parameters using input-output data collected from the process operating in closed-loop control system. When orders and delay-time of the process are known correctly, under some conditions of identifying experiments, it is reported that accurate identification results can be obtained by applying prediction error method. To get accurate estimates, it is necessary to know orders and delay-time of the process. It is difficult to determine them in closed-loop identification, because ill-condition for identification are easily caused by selection of unsuitable order or delay time. Furthermore, the procedures to select orders and delay-time in open-loop identification aren't always available in closed-loop identification. The purpose of this paper is to determine a delay-time under suitable assumption that order of the process are known as the first step.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.05a
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• pp.427-430
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• 2007

Gas turbine disk components have been used by Ni-base superalloys which have high temperature strength for enduring stress induced by high speed rotation. This study introduced the overview of development strategy of precision forging of turbine disk and closed-die forging process for manufacturing good quality gas turbine disk. To make superior quality turbine disk, it is important to select optimal forging process conditions like preform shape, die shape and forging temperature etc. In this paper, closed-die forging process has been studied through the rigid-plastic finite element simulation. Proposed forging process can be used for the successful manufacturing of small-size gas turbine disk.

• Journal of the Korean Institute of Educational Facilities
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• v.8 no.2
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• pp.27-40
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• 2001

The opinion on merits and defects caused the unified-closed of a school facilities have collected by a people and government since the unified-closed system was enforced. There is a problem that the data occurring in the middle of the unified-closed is not analized. Therefore, in this study the target is elementary schools in kyung-gi province which did the unified-closed. First, this study is for analysing which condition influenced to make them. Second, it is for understanding the problems occurred in the process of the unified-closed and presenting the direction of improvement. Third, it is for setting up the planned guide by classification of school facility for the unified-closed which considers the previous problems sufficiently. The range of the study treats of general trend and analysis about the unified-closed of elementary school. The core subject is to analyse the standard and classification of the unified-closed of the object school by the policy of the unified-closed and to compare the carried process of the case school.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.2600-2605
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• 2003

The PBL (Poly-butadiene Latex) production process is a typical batch process. Changes of the reactor characteristics due to the accumulated scaling with the increase of batch cycles require adaptive tuning of the PID controller being used. In this work we propose a tuning method for PID controllers based on the closed-loop identification and the genetic algorithm (GA) and apply it to control the PBL process. An approximated process transfer function for the PBL reactor is obtained from the closed-loop data using a suitable closed-loop identification method. Tuning is performed by GA optimization in which the objective function is given by ITAE for the setpoint change. The proposed tuning method showed good control performance in actual operations.

• 제어로봇시스템학회:학술대회논문집
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• 1995.10a
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• pp.480-483
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• 1995

Identification of a process in closed-loop control system is an important problem in practice. This paper deals with parameter estimation using input-output data of the process operating in a closed-loop system. It is necessary to determine orders and delay-time to get consistent estimators by least square method for input-output data collected from the process. The authors considered a problem to determine delay-time in the condition that orders were known, in last KACC. So we extend the range to determine orders and delay-time in this paper.

• Journal of Institute of Control, Robotics and Systems
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• v.7 no.6
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• pp.494-501
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• 2001

In this paper an ANFIS(Adativo Neuro-Fuzzy Inference System)- based fault detection and diagnosis for a closed loop control system is proposed. The proposed diagnostic system contains two ANFIS. One is run as a parallel model within the model in closed loop control(MCL) and the other is run as a series-parallel model within the process in closed loop(PCL) for the generation of relevant symptoms for fault diagnosis. These symptoms are further processed by another classification logic with simple rules and neural network for process and controller fault diagnosis. Experimental results for a DC shunt motor control system illustrate the effectiveness of the proposed diagnostic scheme.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.15 no.2
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• pp.151-160
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• 2011

Typically, it is hard to find a closed form solution of option pricing formula under an asset governed by a change point process. In this paper we derive a closed-form solution of the valuation function for an American perpetual put option under an asset having a change point. Structural changes are formulated through a change-point process with a Markov chain. The modified smooth-fit technique is used to obtain the closed-form valuation function. We also guarantee the optimality of the solution via the proof of a corresponding verification theorem. Numerical examples are included to illustrate the results.

• Korean Journal of Chemical Engineering
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• v.35 no.11
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• pp.2150-2156
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• 2018

We suggest a systematic method for obtaining the optimal compression ratio in the multi-stage closed-loop compression process of carbon dioxide. Instead of adopting the compression ratio of 3 to 4 by convention, we propose a novel approach based on mathematical analysis and simulation. The mathematical analysis prescribes that the geometric mean is a better initial value than the existing empirical value in identifying the optimal compression ratio. In addition, the optimization problem considers the initial installation cost as well as the energy required for the operation. We find that it is best to use the fifth stage in the general closed-loop type carbon dioxide multi-stage compression process.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.727-730
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• 2004

Closed-cell type barrier ribs such as honeycomb, SDR, inverse SDR and waffle types were produced using capillary molding process. Phosphor layers were formed by osmosis coating process on those barrier ribs. Using the rear plate with closed-cell ribs, the luminance and its efficiency was measured. The results demonstrated a significant improvement in efficiency by combining closed-cell type ribs with a new phosphor forming technology