• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.6
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• pp.1-6
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• 2015

Tool condition monitoring plays one of the most important roles in the improvement of both machining quality and productivity. In this regard, various process signals and monitoring methods have been developed. However, most of the existing studies used cutting force or acoustic emission signals, which posed risks of interference with the machining system in dynamics, fixturing, and machining configuration. In this study, a feed motor current signal is used as a process signal representing process and tool states in tool breakage monitoring based on an adaptive autoregressive model and unsupervised neural network. From the experimental results using various cases of tool breakage, it is shown that the developed system can successfully detect tool breakage before two revolutions of the spindle after tool breakage.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.4 no.2
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• pp.46-53
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• 1995

In this study, Wear of a ceramic cutting tool for hardened STD11 steel was investigated. Under the finish machining condition. DOC notch wear of a ceramic cutting tool was mostly occurred earlier than flank and crater wear were proceeded. The relations of DOC notch wear, which was characteristically produced at the beginning of cutting. to cutting speed, feed, depth of cut, and nose radius of a ceramic cutting tool were examined. Effective approach angle, which is a function of cutting conditions, and boundary area were suggested, and then the influence of those was investigated, The following conclusions were obtained: (1)as cutting speed was increasing. DOC notch wear was decreasing (2) the cutting condition that magnitude of slendermess ratio was made small, was favorable for DOC notch wear, (3) as depth of cut was smaller, the influence of feed on DOC notch wear was also smaller, (4) DOC notch wear was mainly influenced by effective approach angle, but by boundary area in the range of low feed.

• Journal of Korean Society of Water and Wastewater
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• v.21 no.6
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• pp.717-726
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• 2007

Fully-grown flocs in a mixing tank of membrane filtration with dead-end membrane are ruptured while passing through a pump and the ruptured flocs are aggregated again in a Membrane-Feed-Pipe (MFP). To look at more details, this study tries to relate the reaggregation to a parameter of mixing intensity in MFP, i.e., G-value. The G-value is a function of Reynolds number, pipe diameter, friction factor and average velocity in MFP. To deal with polydispersity condition, we develop a representative particle size called in this study EDPD (Effective Diameter for Polydispersity condition in Dead-end filtration). The experimental results show that as the G-value increases, the EDPD decreases and also the cake resistance increases. Through comparison between EDPD and cake resistance, these results show that cake resistances are controlled by reaggregation phenomenon in MFP. The effect of detention time in MFP, however, does not affect the reaggregation of the broken flocs as G-values are increased.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.5
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• pp.14-21
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• 2010

In this study, presintered low purity alumina ceramics were machined with various tools to clarify the effects of the tool material, cutting condition and tool geometry on machinability. The main conclusions obtained were as follows. (a)The wear of tungsten carbide tool becomes smaller with the increase of the feed and clearance angle, and with the decrease of rake angle, especially exhibiting considerably smaller wear with both the decrease of rake angle and the increase of clearance angle. (b) So far as turning the ceramic presintered at low temperature, the diamond tool shows the best performance with higher feed. (c) The effect on the tool wear of the feed, clearance angle and rake angle becomes smaller in turning the ceramic presintered at higher temperature. (d) The tool wear is not severely affected by the depth of cut.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1995.03a
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• pp.54-61
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• 1995

Simultaneous forward-backward extrusion upsetting has been carried out by ratray forging. Two materials has been used commericaly 6.61 aluminium ally and 0.2% steel. The effects of working conditions ; spiral feed ; initial aspect ration of specimen and lubricating condition on the backward and forward extrusion were clarified. The extrusion length increases a sthe aspect rationof the specimen increases, the backward extrusion lengthbeing relatively larger than the forward one. The effects of the spiral feed and the material on the extrusion lengthis remarkably large for the large spiral feed.

• Journal of Veterinary Clinics
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• v.16 no.2
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• pp.257-264
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• 1999

The objective of this study was to estimate the possibility of use as a crude feed about Korean pine foliage. Foliage was fermented aerobic and anaerobic state. And then, it was fed Korean native bull 5 to 6 month old. Bulls were fed control (n=4), aerobic fermented (n=4) and anaerobic fermented (n=4) feed 30 percent of total ration. Bulls were examined with blood sample and body weight on day 0, 60, 120 and 180. There were no differences on complete blood cell count serum chemistry and incidence of disease among groups for experiment period. Also, electrolytes (Ca, Mg, P) balance were good condition. Experimental feed did not induced toxicosis in kidney and liver, Fermented foliage and leaves of Korean softwood were efficient crude feed in carbohydrate, fat and protein metabolism. Experimental feed induced growth of Korean native bull body weight in growing stage without retard. In addition to anaerobic fermented feed has a more higher growth rate than control feed. Our conclusion is that fermented softwood substitute some part of ration, minimum 30 percent, in growing stage of a Korean native bull.

• Journal of the Korean Society for Heat Treatment
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• v.25 no.1
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• pp.14-21
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• 2012

The effects of cutting condition and tempering temperature for the shape of cutting chip were investigated. For this purpose, a lead-free brass containing 1wt.% of Bi extruded at $750^{\circ}C$ in straight turning was used in this study. The cutting chip preferred was mainly found to be loose form of arc chips with curling discontinuity, and these were formed by shear fracture. However, some of fragmental element chip were found to be mixed when tempering temperature was as high as $500^{\circ}C$. The form and size of chip was more affected by feed rate than by tempering temperature and cutting rate. In addition, the cutting surface was observed to be formed more rough in the case of high feed rate and low cutting rate compared to low feed rate and high cutting rate.

• Design & Manufacturing
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• v.17 no.2
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• pp.15-21
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• 2023

In this study, a diamond turning machine and a laser-assisted machining module were utilized for the complex combined cutting of aspheric shapes and fine patterns on the surface of high-hardness brittle material, silicon. The analysis of material's form accuracy and corrective machining was conducted based on key factors such as laser output, rotational speed, feed rate, and cutting depth to achieve form accuracy below 1 ㎛ and surface roughness below 0.1 ㎛. The cutting condition and corrective machining methods were investigated to achieve the desired form accuracy and surface roughness. The rotational speed of the spindle and the linear feed rate of the diamond turning machine were varied in five stages for the cutting condition test. Surface roughness and form accuracy were measured using both a contact surface profilometer and a non-contact surface profilometer. The experimental results revealed a tendency of improved surface roughness with increased rotational speed of the workpiece, and the best surface roughness and form accuracy were observed at a feed rate of 5 mm/min. Furthermore, based on the cutting condition experiments, corrective machining was performed. The experimental results demonstrated an improvement in form accuracy from 0.94 ㎛ to 0.31 ㎛ and a significant reduction in the average value of the surface roughness curve from 0.234 ㎛ to 0.061 ㎛. This research serves as a foundation for future studies focusing on the machinability in relation to laser output parameters.

• Journal of Korean Society of Water and Wastewater
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• v.25 no.3
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• pp.399-405
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• 2011

In a desalination technology using RO membranes, chemical cleaning makes damage for membrane surface and membrane life be shortened. In this research cleaning technology using direct osmosis (DO) was introduced to apply it under the condition of high pH and high concentration of feed. When the high concentration of feed is injected to the concentrate side after release of operating pressure, then backward flow occurred from treated water toward concentrated for osmotic pressure. This flow reduces fouling on the membrane surface. Namely, flux of DO was monitored under pH 3, 5, 10 and 12 conditions at feed concentrations of NaCl 40,000 mg/L, 120,000 mg/L and 160,000 mg/L. As a result, DO flux in pH 12 increased about 21% than pH 3. DO cleaning was performed under the concentrate NaCl 160,000 mg/L of pH 12 during 20 minutes. Three kinds of synthetic feed water were used as concentrates. They consisted of organic, inorganic and seawater; chemicals of SiO2 (200 mg/L), humic acid (50 mg/L) sodium alginate (50 mg/L) and seawater. As a result, fluxes were recovered to 17% in organic fouling, 15% in inorganic fouling and 14% of seawater fouling after cleaning using DO under the condition of concentrate NaCl 160,000 mg/L of pH 12.

• The Transactions of the Korean Institute of Power Electronics
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• v.15 no.3
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• pp.226-234
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• 2010

This paper proposes an improved feed-forward controller that calculates the gain value by estimating the changed boost inductance in practical operating condition of transformer. The boost inductance is estimated by the measurement of input current and voltage. The estimated boost inductance is optimized by the least square method. The proposed feed-forward controller can be achieved the robust control through the gain value calculating the estimated boost inductance despite of the changed condition of transformer and can minimize the interference phenomenon by reducing the harmonics of input current. The validity of proposed technique is verified through the simulation and experiment.