• Journal of the Semiconductor & Display Technology
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• v.12 no.4
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• pp.9-13
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• 2013

Lapping is a very complicated and random process resulting from the variation of abrasive grains in its sizes and shapes and from the numerous factors having an effect on the process quality. This paper presents a study of a $2^4$ full factorial experimental design and analysis to optimize surface quality in lapping operation. The optimization of the factors to obtain minimum surface roughness was carried out by incorporating effect plots, main effect plots, interaction plots, analysis of variance(ANOVA), surface plots, and contour plots. The statistical design experiments, designed to reduce the total number of experiments required, indicated that, within the selected conditions, all the parameters influenced at a significance level of 5%. In addition, some of the possible interactions between these parameters also influenced the lapping process, especially those that were of third order. A regression model was suggested and fitted the experimental data very well.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.10a
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• pp.242-248
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• 2000

This paper has focused on the optimization of the cutting parameters for turning operation based on the Taguchi method. Four cutting parameters, namely, cutting speed, feed, depth of cut and nose radius are optimized with consideration of the surface roughness. The design and analysis of experiments are conducted to study the performance characteristic. The effects of these parameters on the surface roughness have been investigated using the signal-to-noise (S/N) ratio, analysis of variance (ANOVA). The experiments have been peformed using coated tungsten carbide inserts without any cutting fluid. Experimental results illustrate the effectiveness of this approach.

• Journal of the Korean Society of Safety
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• v.29 no.3
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• pp.136-142
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• 2014

Recently a new version of PRO-LOCA program was released. Using the program, failure probability of pipes can be evaluated considering fatigue and/or stress corrosion crack growth and the effects of various parameters on the integrity of pipes in nuclear power plants can be evaluated quantitatively. The analysis results can be used to establish an inspection plan and to examine the effects of important parameters in a maintenance plan. In this study, sensitivity analyses were performed using the program for several important parameters including sampling method, initial crack size, number of initial fabrication flaws, operation temperature, inspection interval, operation temperature and nominal applied bending stress. The effect of parameters on the leak and rupture probability of pipes was evaluated due to fatigue or stress corrosion crack growth.

• International Journal of Naval Architecture and Ocean Engineering
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• v.12 no.1
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• pp.129-145
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• 2020

The article presents a systematic approach to design of marine navigation channels parameters resulting from manoeuvring and operational safety. Relations between the parameters of waterway system elements and the conditions of safe ship operation have been determined and the objective function of waterway parameters' optimization problems has been minimized with respect to variables of construction and operation costs. These costs have been functionally associated to variables of channel width at the bottom and fairway depth. The method of fairway's width computation at specified safe depth at the preliminary and detailed stages of waterway design has been proposed. The results of this method application have been illustrated with two examples: 1. The modernization of Szczecin-Swinoujscie fairway aimed at accepting vessels of 60,000 DWT capacity. 2. Construction of an approach channel leading to a newly built container terminal in Swinoujscie harbour (Poland), handling ocean-going container ships of 20,000 TEU capacity.

• Journal of Korean Society of Water and Wastewater
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• v.31 no.1
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• pp.1-6
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• 2017

Surge pressure is created by rapid change of flow rate due to operation of hydraulic component or accident of pipeline. Proper control of surge pressure in distribution system is important because it can damage pipeline and may have the potential to degrade water quality by pipe leakage due to surge pressure. Surge relief valve(SRV) is one of the most widely used devices and it is important to determine proper parameters for SRV's installation and operation. In this research, determining optimum parameters affecting performance of the SRV were investigated. We proposed the methodology for finding combination of parameters for best performance of the SRV. Therefore, the objective function for evaluate fitness of candidate parameters and surge pressure simulation software was developed to validate proposed parameters for SRV. The developed software was integrated into genetic algorithm(GA) to find best combination of parameters.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.38 no.3
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• pp.100-107
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• 2015

Recently as the manufacturers want competitiveness in dynamically changing environment, they are trying a lot of efforts to be efficient with their production systems, which may be achieved by diminishing unplanned operation stops. The operation stops and maintenance cost are known to be significantly decreased by adopting proper maintenance strategy. Therefore, the manufacturers were more getting interested in scheduling of exact maintenance scheduling to keep smooth operation and prevent unexpected stops. In this paper, we proposedan integrated maintenance approach in injection molding manufacturing line. It consists of predictive and preventive maintenance approach. The predictive maintenance uses the statistical process control technique with the real-time data and the preventive maintenance is based on the checking period of machine components or equipment. For the predictive maintenance approach, firstly, we identified components or equipment that are required maintenance, and then machine parameters that are related with the identified components or equipment. Second, we performed regression analysis to select the machine parameters that affect the quality of the manufactured products and are significant to the quality of the products. By this analysis, we can exclude the insignificant parameters from monitoring parameters and focus on the significant parameters. Third, we developed the statistical prediction models for the selected machine parameters. Current models include regression, exponential smoothing and so on. We used these models to decide abnormal patternand to schedule maintenance. Finally, for other components or equipment which is not covered by predictive approach, we adoptedpreventive maintenance approach. To show feasibility we developed an integrated maintenance support system in LabView Watchdog Agent and SQL Server environment and validated our proposed methodology with experimental data.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.896-902
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• 2005

An orthopedic surgeon normally gets the operational parameters of total knee arthroplasty from medical images(CT, MRI). Anatomical axis, mechanical axis, the width and height of femur, or tibia are the most important parameters related with accomplishment of TKA. This paper presents a methodology of simulation that virtually operates TKA according to 2D medical images. Using this simulator, some important parameters for operation can be achieved before hand. The simulator provides the 3D computational model of a knee joint and then derives the proper size of implant corresponding to the joint. The whole process of TKA can be simulated such as clipping a knee joint, assembling the joint and its implants, visualizing all the operation steps, deriving some crucial parameters such as anatomical axis and cutting thickness, and predicting the result of TKA. Some examples are given and discussed to validate the methodology.

• Bulletin of the Korean Space Science Society
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• 2004.10b
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• pp.278-280
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• 2004

GPS Navigation Solutions are used for operational orbit determination for the KOMPSAT-1 spacecraft. GPS point position data are definitely affected by systematic errors as well as noise. Indeed, the systematic error effects tend to be longer term since the GPS spacecrafts have periods of 12 hours. And then, the overlap method of determining orbit accuracy is always optimistic because of the presence of systematic errors with longer term effects. In this paper, we investigated the measurement noise and the system error for the KOMPSAT-l GPS Navigation Solutions. To assess orbit accuracy with this type of data, we use longer data arcs such as 5-7 days instead of 30 hour data arc. For this assessment, we should require much more attention to drag and solar radiation drag parameters or even general acceleration parameters in order to assess orbit accuracy with longer data arcs. Thus, the effects of the consideration of the drag, solar radiation drag, and general acceleration parameters were also investigated.

• Journal of Korean Tunnelling and Underground Space Association
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• v.16 no.2
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• pp.203-211
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• 2014

This paper presents the screw conveyor operation efficiency of shield TBM in soft ground. In order to study the screw conveyor operation efficiency, the experimental and theoretical studies were carried out. In experimental study, the operating amounts of muck were examined and compared due to the screw conveyor operating parameters including types (Shaft and Ribbon screw), angles of screw and conveyor. The results obtained from the laboratory model tests were analysed and evaluated to suggest the most suitable muck operating parameters during the shield TBM tunnelling in soft ground. In conclusion, it is found the operation parameters to increase the screw conveyor efficiency. In addition, the information presented in this paper may be useful for developing the design technology of shield TBM in the future.

• Journal of Environmental Science International
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• v.20 no.4
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• pp.501-509
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• 2011

Unlike many laboratory-scale studies on absorption of organic compounds (VOCs), limited pilot-scale studies have been reported. Accordingly, the present study was carried out to examine operation parameters for the effective control of a hydrophilic VOC (methyl ethyl ketone, MEK) by applying a circular pilot-scale packed-absorption system (inside diameter 37 cm ${\times}$ height 167 cm). The absorption efficiencies of MEK were investigated for three major operation parameters: input concentration, water flow rate, and ratio of gas flow-rate to washing water amount (water-to-gas ratio). The experimental set-up comprised of the flow control system, generation system, recirculation system, packed-absorption system, and outlet system. For three MEK input concentrations (300, 350, and 750 ppm), absorption efficiencies approached near 95% and then, decreased gradually as the operation time increased, thereby suggesting a non-steady state condition. Under these conditions, higher absorption efficiencies were shown for lower input concentration conditions, which were consistent with those of laboratory-scale studies. However, a steady state condition occurred for two input concentration conditions (100 and 200 ppm), and the difference in absorption efficiencies between these two conditions were insignificant. As supported by an established gas-liquid absorption theory, a higher water flow rate exhibited a greater absorption efficiency. Moreover, as same with the laboratory-scale studies, the absorption efficiencies increased as water-to-gas ratios increased. Meanwhile, regardless of water flow rates or water-to-gas ratios, as the operation time of the absorption became longer, the pH of water increased, but the elevation extent was not substantial (maximum pH difference, 1.1).