• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.5
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• pp.413-421
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• 2012

In industry, various rotating machinery such as pumps, gas turbines, compressors, electric motors, generators are being used as an important facility. Due to the industrial development, they make high performance(high-speed, high-pressure). As a result, we need more intelligent and reliable machine condition diagnosis techniques. Diagnosis technique using hidden Markov-model is proposed for an accurate and predictable condition diagnosis of various rotating machines and also has overcame the speed limitation of time/frequency method by using compensation of the rotational speed of rotor. In addition, existing artificial intelligence method needs defect state data for fault detection. hidden Markov model can overcome this limitation by using normal state data alone to detect fault of rotational machinery. Vibration analysis of step-up gearbox for wind turbine was applied to the study to ensure the robustness of diagnostic performance about compensation of the rotational speed. To assure the performance of normal state alone method, hidden Markov model was applied to experimental torque measuring gearbox in this study.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2003.11a
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• pp.291-305
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• 2003

In this work we developed the closed-loop model of a paper machine during grade change with the intention to provide a reliable dynamic model to be used in the model-based grade change control scheme. During the grade change, chemical and physical characteristics of paper process change with time. It is very difficult to represent these characteristics on-line by using physical process models. In this work, the wet circulation part and the drying section were considered as a single process and closed-loop identification technique was used to develop the grade change model. Comparison of the results of numerical simulations with plant operation data demonstrates the effectiveness of the model identified.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.5
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• pp.92-99
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• 1997

A model reference adaptive control(MRAC) theory is very useful for controlling a plant of which the parameters are unknown or vary during operation usint only input-output signal of plant. In this study, 2' nd order discreter time MRAC controller is designed for an electrohydraulic position control system which is represented with nonlinear mathematical model and the least square method is adopted for the para-meter adjustment law. This control algorthm is applied to the position control of electrohydraulic servosystem through computer simulation and the effect of the change of load, sampling time upon the performance following reference model and upon the performance of estimating plant parameters are examined.

• Journal of Korean Institute of Industrial Engineers
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• v.11 no.2
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• pp.47-56
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• 1985

This paper considers a two-product three-facility production planning model, where facility 1 produces product 1 to satisfy its own market requirements and supplies input to facility 2, and facility 2 requires another input from facility 3 (outside supplier). The objective is to determine the optimal production amount in each period in order to satisfy the dynamic demands on time, which minimizes the total cost of production and storage. The set-up cost is incurred jointly from the multi-facility operations.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.212-215
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• 2003

In this paper, a model pole transformer was designed to improve the reliability of pole transformers and its short circuit withstand strength was tested. The failure causes of the pole transformers which had been operated in the field were analyzed and several patterns of the causes were determined. A novel countermeasure was devised to prevent the failures of the pole transformers in advance. A model pole transformer was designed and made in accordance with the given specifications to strengthen the short circuit withstand capability and its characteristic was tested. As a result, the advanced performance of the model pole transformer was confirmed and novel techniques in manufacturing process was suggested. It is considered that all the methods employed in the developing process will be helpful to design and manufacture the pole transformers thus the reliability of pole transformers in distribution lines will be improved.

• Journal of Ecology and Environment
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• v.39 no.1
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• pp.61-70
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• 2016

Major objectives of the study were to analyze chemical and biological influences of the river ecosystem on the artificial weir construction at three regions of Sejong-Weir (S_j-W), Gongju-Weir (G_j-W), and Baekje-Weir (B_j-W) during 2008-2012. After the weir construction, the discharge volume increased up to 2.9 times, and biological oxygen demand (BOD) and electrical conductivity (EC) significantly decreased (p < 0.05). Also, the decrease of total phosphorus (TP) was also evident after the weir construction, but still hyper-eutrophic conditions, based on criteria by , were maintained. Multi-metric model of Index of Biological Integrity (IBI) showed that IBI values averaged 21.0 (range: 20-22; fair condition) in the B_wc, and 14.3 (range: 12-18; poor condition) in the A_wc. The model values of IBI in S_j-W and G_j-W were significantly decreased after the weir construction. The model of Self-Organizing Map (SOM) showed that two groups (cluster I and cluster II) of B_wc and A_wc were divided in the analysis based on the clustering map trained by the SOM. Principal Component Analysis (PCA) was similar to the results of the SOM analysis. Taken together, this research suggests that the weir construction on the river modified the discharge volume and the physical habitat structures along with distinct changes of some chemical water quality. These physical and chemical factors influenced the ecosystem health, measured as a model value of IBI.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.573-574
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• 2013

• Transactions of Materials Processing
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• v.20 no.7
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• pp.512-517
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• 2011

TRB(Tailor Rolled Blank) is an emerging manufacturing technology by which engineers are able to change blank thickness continuously within a sheet metal. TRB door inner panels with required larger thicknesses can be used to support localized high loads. In this study, the aluminum alloy 5J32 TRB sheet is used for a door inner panel application. The TRB material properties were varied by using three heat treatment conditions. In order to predict the failure of the aluminum TRB during simulation, the forming limit diagram, which is used in sheet metal forming analysis to determine the criterion for failure, was investigated. Full-field photogrammetric measurement of the TRB deformation was performed with an ARAMIS 3D system. A FE model of the door inner panel was created using Autoform software. The material properties obtained from the tensile tests were used in the numerical model to simulate the door inner of AA 5J32 for each heat treatment condition. After finite element analysis for the evaluation of formability, a prototype front door panel was manufactured using a hydraulic press.

• Journal of Power System Engineering
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• v.11 no.4
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• pp.78-85
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• 2007

In order to analyze accurately the vibration of a structure by using the finite element method (FEM), we have to model a analytical structure as a numerical model with many degrees-of-freedom. However, in this case, the FEM needs much computation time and storage. The authors developed the finite element-transfer stiffness coefficient method (FE-TSCM) for overcoming the drawback of the FEM. In this paper, the authors apply the FE-TSCM to the in-plane vibration analysis of general plates with various shapes. Two numerical examples, a rectangular plate and a triangular plate, are used to compare the results of the FE-TSCM and the FEM. Through the numerical calculation, we confirm that the FE-TSCM can be applied to the in-plane free or forced vibration analysis of the general plates with various shapes and is effective to in-plane vibration analysis of general plates.

• The Korea Journal of Herbology
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• v.24 no.2
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• pp.39-48
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• 2009

Objectives : To clarify the possible effect of JS (Juglans sinensis), PCF (Psoralea corylifolia L.), and J+P(JS+PCF), we examined their influence on the development of pulmonary eosinophilic inflammation in the asthmatic murine model. Methods : All mice were immunized on two different days (21 days and 7 days before inhalational exposure) by intraperitonial injections of 0.2 ml alum-precipitated Ag containing 100 ${\mu}$g of OVA bound to 4 mg of aluminum hydroxide in PBS. Seven days after the second sensitization, mice were exposed to aerosolized ovalbumin for 30 minutes/day on 3 days/week for 8 weeks (at a flow rate of 250 L/min, 2.5% ovalbumin in normal saline) and, JS, PCF and J+P (200 mg/kg, 400 mg/kg) were orally administered 3 times per week for 8 weeks. Results : The suppressive effects of JS, PCF, and J+P were demonstrated by the accumulation of eosinophils into airways, with the reduction of eosinophils and lung leukocytes. These were correlated with the marked reduction of IL-4, IL-5, IL-13 levels in the BALF and serum. OVA-specific IgE levels were also decreased in serum and BAL from these mice. And also JS, PCF, and J+P decreased eosinophilic CCR3 and CD11b expression in lung tissue. Conclusions : These results indicate that JS, PCF, and J+P have deep inhibitory effects on airway inflammation and hyper-responsiveness in the asthmatic murine model. The suppression of IL-5, IgE, and eosinophilils and the increase of IFN-${\gamma}$ production in BALF seem to contribute to these effects. Specially, esosinophils and TNF-a in J+P combination group were significantly reduced in BALF and lung tissue. Hence, the results indicated that JS, PCF, and J+P could act as an immuno-modulator which possesses anti-inflammatory and anti-asthmatic property by modulating the imbalance between Th1 and Th2 cytokines.