• 대한전기학회논문지:시스템및제어부문D
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• 제52권11호
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• pp.619-625
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• 2003

We proposed an optimum PID controller design method of the Smith Predictor It can be applied to various processes. The real process is approximated via the second order plus time delay model (SOPTD) whose parameters are specified through a model reduction algorithm. We already proposed a new model reduction method that considered four point in the Nyquist curve to reduced the steady state error between the real process model and the reduced model using the gradient decent method and the genetic algorithms. In addition, the Smith predictor is used to compensate time delay of the real process model. In this paper, the new optimum parameter tuning algorithm for PID controller of the Smith Predictor is proposed through ITAE as performance index. The Simulation results show the validity and improvement of performance for various processes.

• 한국입자에어로졸학회지
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• 제12권3호
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• pp.57-63
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• 2016

The laser-induced breakdown spectroscopy (LIBS) has been used for rapid detection of elemental compositions of various materials in multi-media (solid, liquid, gas, and aerosols). In this study, the aerosol-LIBS has been developed for real-time monitoring of process-induced particles produced during the semiconductor manufacturing. The developed aerosol-LIBS mainly consists of laser, optics, spectrometer, and aerosol chamber. A new aerosol chamber was constructed for the aerosol-LIBS to be applied for various semiconductor manufacturing process, including exhaust tubes, and low pressure and high temperature chamber. The aerosol-LIBS was evaluated by using laboratory generated aerosols for detection of various elements. As a result, P, Fe, Mg, Cu, Co, Ni, Ca, Na, and K emission lines were successfully detected by the aerosol-LIBS. Further evaluation of the aerosol-LIBS is being conducted.

• 한국멀티미디어학회논문지
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• 제22권3호
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• pp.366-373
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• 2019

The development of monitoring and analysis systems to increase productivity while saving energy is needed as a method to reduce huge amount of energy consumed in the process of producing large forged products. In this paper, we propose a system to monitor and analyze energy usage in real-time collected from gas-meter, wattmeter, and thermometer based on IoT installed in forging factories. The system consists of a data collection server for collecting and processing data from IoT- based platform and existing SCADA equipment and ERP/MES system in forging factories, and an application server for providing services to users. To develop the system, the overall system structure is logically diagrammed, and the databases configuration and implementation modules to efficiently store and manage data are presented. In the future, the system will be utilized to reduce energy consumption by analyzing energy usage pattern and optimizing process works with real-time energy usage and production process data for each facility.

• Design & Manufacturing
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• 제17권3호
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• pp.34-40
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• 2023

In this study, real-time collection of mold vibration signals during injection molding processes was achieved through IoT devices installed on the mold surface. To analyze changes in the collected vibration signals, injection molding was performed under six different process conditions. Analysis of the mold vibration signals according to process conditions revealed distinct trends and patterns. Based on this result, cosine similarity was applied to compare pattern changes in the mold vibration signals. The similarity in time and acceleration vector space between the collected data was analyzed. The results showed that under identical conditions for all six process settings, the cosine similarity remained around 0.92±0.07. However, when different process conditions were applied, the cosine similarity decreased to the range of 0.47±0.07. Based on these results, a cosine similarity threshold of 0.60~0.70 was established. When applied to the analysis of mold vibration signals, it was possible to determine whether the molding process was stable or whether variations had occurred due to changes in process conditions. This establishes the potential use of cosine similarity based on mold vibration signals in future applications for real-time monitoring of molding process changes and anomaly detection.

• 대한인간공학회지
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• 제26권2호
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• pp.149-155
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• 2007

Recently, various devices requiring text input such as mobile phone IPTV, PDA and UMPC are emerging. The frequency of text entry for them is also increasing. This study was focused on the evaluation of Korean text entry interface. Various models to evaluate text entry interfaces have been proposed. Most of models were based on human cognitive process for text input. The cognitive process was divided into two components; visual scanning process and finger movement process. The time spent for visual scanning process was modeled as Hick-Hyman law, while the time for finger movement was determined as Fitts' law. There are three questions on the model-based evaluation of text entry interface. Firstly, are human cognitive processes (visual scanning and finger movement) during the entry of text sequentially occurring as the models. Secondly, is it possible to predict real text input time by previous models. Thirdly, does the human cognitive process for text input vary according to users' text entry speed. There was time gap between the real measured text input time and predicted time. The time gap was larger in the case of participants with high speed to enter text. The reason was found out investigating Eye-Hand Coordination during text input process. Differently from an assumption that visual scan on the keyboard is followed by a finger movement, the experienced group performed both visual scanning and finger movement simultaneously. Arrival Lead Time was investigated to measure the extent of time overlapping between two processes. 'Arrival Lead Time' is the interval between the eye fixation on the target button and the button click. In addition to the arrival lead time, it was revealed that the experienced group uses the less number of fixations during text entry than the novice group. This result will contribute to the improvement of evaluation model for text entry interface.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1988년도 한국자동제어학술회의논문집(국내학술편); 한국전력공사연수원, 서울; 21-22 Oct. 1988
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• pp.722-724
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• 1988

In this study, 8 ch. FECG signal storage system with general cassette recorder and amplifier is developed, and simulated LMS algorithm. In future we construct real time FECG monitor system that is used digital signal processor.

• 한국해양공학회지
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• 제13권3호통권33호
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• pp.83-91
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• 1999

Taking a view of joining by welding the IN713C to SCM440 and SCM415 steel in production of turbochargers, the frictin welding process may be utilized as a new approach for joining them of other conventional welding processes. It is because the friction welding has more technical and technical and economic advantages than the other welding processes. As this welding process has the characteristics such as curtaliment of production time and materials and cost reduction, etc.. So, this paper deals with determining the preper friction welding condition and analyzing various mechanical properties of friction welded joints of the super heat resisting steel to alloy stee(IN713C to SCM440 and SCM415). And the in-process real-time weld quality evaluation technique by acoustic emission during friction welding of IN713C to SCM440 and SCM415 steels with higher confidence and relibility has been much required even though it might be the first trial approach for developing it. Then, this first study aimed to develop the optimization of dissimilar friction welding of heat resisting steels (INC713 to SCM440, SCM415) for turbine, considering on strength and toughness.

• Journal of Computational Design and Engineering
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• 제2권3호
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• pp.148-156
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• 2015

Increased competitive challenges are forcing companies to find better ways to bring their applications to market faster. Distributed development environments can help companies improve their time-to-market by enabling parallel activities. Although, such environments still have their limitations in real-time communication and real-time collaboration during the product development process. This paper describes a web-based collaborative framework which has been developed to support the decision making on a 3D design developing process. The paper describes 3D design file for the discussion that contains all relevant annotations on its surface and their visualization on the user interface for design changing. The framework includes a native CAD data converting module, 3D data based real-time communication module, revision control module for 3D data and some sub-modules such as data storage and data management. We also discuss some raised issues in the project and the steps underway to address them.

• 한국분말재료학회지
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• 제27권6호
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• pp.484-489
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• 2020

In this study, acoustic and viscosity data are collected in real time during the ball milling process and analyzed for correlation. After fast Fourier transformation (FFT) of the acoustic data, changes in the signals are observed as a function of the milling time. To analyze this quantitatively, the frequency band is divided into 1 kHz ranges to obtain an integral value. The integrated values in the 2-3 kHz range of the frequency band decrease linearly, confirming that they have a high correlation with changes in viscosity. The experiment is repeated four times to ensure the reproducibility of the data. The results of this study show that it is possible to estimate changes in slurry properties, such as viscosity and particle size, during the ball milling process using an acoustic signal.

• 한국정보통신학회논문지
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• 제3권1호
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• pp.209-221
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• 1999

실시간 스케줄가능성 분석을 위한 여러 가지 방법들이 제안되었지만, 이들은 프로세스의 모든 상태공간을 추적하거나 고정 우선 순위 스케줄링 방법을 사용하기 때문에 시간 및 공간에 대한 복잡성의 증가를 야기한다. 따라서 상태공간의 수를 줄임으로써 보다 빠른 시간에 스케줄가능성을 판단하는 방법이 필요하다. 본 논문에서는 프로세스 대수의 전이규칙을 이용하여 번역시간에 결정될 수 있는 프로세스의 최소 수행시간, 주기, 마감시간, 동기화 시간을 고려하여 실시간 프로세스가 마감시간을 지키는가를 판단하는 개선된 알고리즘을 제안 및 구현한다. 구현 결과를 통하여 모든 상태 공간을 검색하지 않고도 스케줄가능성을 판단하는 효과적인 성능을 보였다.