• Environmental Engineering Research
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• v.20 no.4
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• pp.392-396
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• 2015

This work aims to investigate the oily wastewater treatment by the electrocoagulation-flotation (ECF) and propose a mathematical model for the efficiency prediction. Cutting oil was used to prepare the synthetic oily wastewater with submicron droplet sizes. The chemical coagulation by aluminium sulfate was firstly tested following by the electrocoagulation-flotation with aluminium electrodes. Both processes gave the effective treatment performance with the efficiencies higher than 90%. However, the ECF consumed less aluminium dosage as well as produced less sludge, which were its advantage on the chemical coagulation. The performance of the ECF was found to be affected by the current density, oil concentration, and reaction time according to the analysis by the design of experiment (DOE). Finally, the prediction model was proposed by two approaches, including linear and logarithm function. The latter model gave more accuracy prediction results in terms of treatment efficiency and duration in the lag and stable stages.

• Explosives and Blasting
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• v.22 no.3
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• pp.71-78
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• 2004

Explosive blasting, hydaulic power unit and rock splitter are typically utilized for rockmass breakage and cutting in reconstruction of building structures and other construction site. Hydraulic rock cutting method, that can be utilized any weather conditions, has been applied mainly by experience for controling damages caused by vibration, noise and rock cuttings, and reducing damage claim by protecting adjacent structures. However, it is required to understand the characteristics of rockmass to improve operation efficiency. Although every cutting method has its own advantage, but it should be applied by considering site circumstance and rockmass properties in details to maximize the operation efficiency and economic feasibility.

• Journal of Korean Tunnelling and Underground Space Association
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• v.23 no.3
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• pp.167-181
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• 2021

New type of rock excavation method using a waterjet system is being developed to secure economic feasibility and to reduce vibrations during excavation. In waterjet rock excavation, overlapping of cutting width is essential for high efficiency. In this study, cutting experiments for granite specimens were performed using abrasive waterjet system according to the overlapping ratio and standoff distance. Based on the experimental results, the granite cutting performance was analyzed according to the overlapping ratio. In addition, removal shapes of the cross-section were analyzed in terms of the cutting depth, width, and volume after waterjet cutting. When the overlapping ratio is less than 58%, rock specimens are partially removed due to the insufficient overlapping ratio. However, when the overlapping ratio exceeds 67%, overcutting phenomenon is observed. For the partial overlapping ratio (i.e., 25~75%), cutting efficiency is increased in the removal volume. This study is expected to be used as the important basic data for determining the optimum overlapping ratio when the waterjet system is applied for rock excavation.

• 제어로봇시스템학회:학술대회논문집
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• 1989.10a
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• pp.663-668
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• 1989

Control methods to achieve efficient and accurate deburring robots are proposed. For efficiency, cutting speed is controlled adoptively with the cutting load. For accuracy, it adopts repetitive control. Since usual repetitive control cannot afford dynamical speed changes, the proposed method controls in an interpolating manner using several waveforms stored in the controller. Successful experimental results axe shown.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.6
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• pp.104-110
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• 2015

LED has added value as a lighting source in the illuminating industry because of its high efficiency and low power consumption. In LED production processes, the chip cutting process, which mainly uses a scribing process with a laser has an effect on quality and productivity of LED. This scribing process causes problems like heat deformation, decreasing strength. The inner laser method, which makes a void in wafer and induces self-cracking, can overcome these problems. In this paper, cutting sapphire wafer for fabricating LED chip using the inner laser scribing process is proposed and evaluated. The aim is to settle basic experiment conditions, determine parameters of cutting, and analyze the characteristics of cutting by means of experimentation.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.9
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• pp.2145-2152
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• 2013

Paper manufacturing industries have huge facilities with automatic equipments. Especially, in order to improve the efficiency of the paper manufacturing processes, it is necessary to detect the paper cutting defect effectively and to classify the causes correctly. In this paper, we review the problems of web monitoring system and web inspection system that have been traditionally used in industries for defect detection. Then we propose a novel paper cutting defect detection method based on the local binary pattern analysis and its implementation to mitigate the practical problems in industry environment. The proposed algorithm classifies the defects into edge-type and region-type and then it is shown that the proposed system works stably on the real paper cutting defect detection system.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.4
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• pp.694-704
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• 1988

A recursive parameter estimation scheme utilizing the variance perturbation method is applied to the workpiece deflection model during CNC turning process, in order to improve the cylindricity of slender workpiece. It features that it is based on exponentially weighted recursive least squares method with post-process measurement of finish surfaces at two locations and it does not require a priori knowledge on the time varying deflection model parameter. The measurements of finish surfaces by using two proximity sensors mounted face to face enable one to identify the straightness, guide-way, run-out eccentricity errors. Preliminary cutting tests show that the straightness error of the finish surface due to workpiece deflection during cutting is most dominant. Identifying the errors and recursive updating the parameter, the off-line control is carried out to compensate the workpiece deflection error, through single pass cutting. Experimental results show that the proposed method is superior to the conventional multi-pass cutting and the direct compensation control in cutting accuracy and efficiency.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.2
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• pp.28-33
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• 2017

Recently, the operation of precision pocket machining has been studied for the high speed and accuracy in industry to increase production and quality. Moreover, the demand for products with complex 3D free-curved surface shapes has increasing rapidly in the development of computer systems, CNC machining, and CAM software in various manufacturing fields, especially in automotive engineering. The type of aluminum (Al6061) that is widely used in aerospace fields was used in this study, and end-mill down cutting was conducted in fillet cutting at a corner with end-mill tools for various process conditions. The experimental results may demonstrate that the end mill cutter with four blades is more advantageous than that of the two blades on shape forming in the same condition precise machining conditions. It was also found that cutting forces and tool deformation increased as the cutting speed increased. When the tool was located at $45^{\circ}$ (four locations), the corner was found to conduct the maximum cutting force rather than the start point of the workpiece. The experimental research is expected to increase efficiency when the economical precision machining methods are required for various cutting conditions in industry.

• Journal of Korean Tunnelling and Underground Space Association
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• v.23 no.3
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• pp.199-209
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• 2021

Alternative methods of rock cutting have been introduced to substitute and to improve the traditional mechanical rock excavation methods (e.g., TBM and roadheader). Undercutting methods have been recently studied in some countries. In undercutting, several additional cutting parameters are involved in its cutting process compared to the traditional rock-cutting. As a fundamental study, this paper introduces the concept of undercutting method with actuated disc, lab-scaled testing system, and testing procedures of undercutting by the system. Also, we present the calculation methods of cutter forces and specific energy, and discuss the results of undercutting tests compared to those of traditional rock-cutting methods.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.62-65
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• 2003

VLM-ST process requires an additional human interaction due to the manual stacking and bonding. Hence, building time, building cost and the part quality are dependent on the skill of labor. In this present work, a novel rapid prototyping (RP) process, as an automatic VLM-ST (VLM-STA), has been proposed to improve building efficiency of VLM-ST process and reliability of products. The apparatus of VLM-STA is designed to embody the process. Several characteristics of the proposed process and the apparatus are discussed. In order to examine the efficiency and the applicability of the proposed process, various three-dimensional shapes, such as a piston and a human head shape, are fabricated on the apparatus.