• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.8
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• pp.2508-2515
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• 1996

Determination of an optimal feed rate is valuable in the sense of the precision and efficient machining. In this regard, a new surface roughness model for the face milling operation that considered the radial and axal runouts of the inserts in the cutter body was developed. The validity of the model was proved through the cutting experiments, and the model is able to predict the real machined surface roughness exactly with the information of the insert runouts and the cutting conditions. From the estimated surface roughness value, the maximum feed rate that obtains a maximum naterial removal rate under the given surface roughness constraint can be selected by using a bisection method. Therefore, this mehod for optimizing the feed rate can be well applied to the using a bisection method. Therefore, this method for optimizing the feed rate can be well applied to the using selsction of the cutting condition during the NC data generation in CAM.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.10
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• pp.27-33
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• 2019

The aviation industry has grown beyond the simple processing and assembling of aircraft parts and now designs and exports finished aircraft. In this study, the vertical CNC milling rotational speed and feed rate were parameters to investigate the life of tools according to their shape: (flat, round, and ball end mill) in the rough cutting of titanium. These tools are widely used in aircraft manufacturing and assembly. The purpose of this study is to measure the cutting temperature generated during the cutting process and calculate the rate of tool wear. This will be accomplished by measuring the tool weight before and after cutting the specimen and to compare it with the results of previous studies. Our study showed that the maximum cutting temperature increased as cutting time, tool rotational speed, and feed rate increased. The highest cutting temperatures were recorded for the ball, round, and flat end mill, respectively. Tool wear for the ball, round, and flat end mill increased as the speed and feed rate increased. The flat end mill exhibited the highest rate of wear from a minimum of 0.62% to a maximum of 2.88%.

• Journal of Pharmaceutical Investigation
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• v.23 no.2
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• pp.81-87
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• 1993

Five crystalline forms of cimetidine, four anhydrous and a monohydrate, have been prepared, and their thermal behavriours have been studied by differential thermal analysis and thermo-gravimetry. The dissolution rates of the five forms were determined in distilled water at $37^{\circ}C$. The results showed a significant difference in the dissolution rate. Polymorphic transformation occurred spontaneously during storage at room condition and was accelerated by applied energy during formulation process-milling.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1998.10a
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• pp.26-31
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• 1998

The effect of tool angles on the surface roughness in face milling is studied. First, the relation between tool angles and rotation angles is identified. Using this relationship, it is obtained that the projection of insert nose shape on cutting profile, which is a part of ellipse. The effect of spindle tilt is also considered for the tool angles. It si shown that tool angles along with nose radius and feed rate have an effect on surface roughness.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.05a
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• pp.143-144
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• 2015

Here we report the Ar-ion milling rates of ultrathin Si and GaAs single crystals. The thickness change is measured using convergent beam electron diffraction (CBED) technique with the help of Bloch wave simulation method. This study suggests the experimental procedures to determine the references for an etching rate to reduce a sample thickness or to remove the damaged sample surface using Ar-ion source.

• Journal of Powder Materials
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• v.10 no.4
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• pp.270-274
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• 2003

Recently, the fabrication process of W-Cu nanocomposite powders has been researched to improve the sinterability by mechanochemical process (MCP), which consists of ball milling and hydrogen-reduction with W- and Cu-oxide mixture. However, there are many control variables in this process because the W oxides are hydrogen-reduced via several reduction stages at high temperature over 80$0^{\circ}C$ with susceptive reduction conditions. In this experiment, the W-15 wt%Cu nanocomposite powder was fabricated with the ball-milling and hydrogen-reduction process using W and CuO powder. The microstructure of the fabricated W-Cu nanocomposite powder was homogeneously composed of the fine W particles embedded in the Cu matrix. In the sintering process, the solid state sintering was certainly observed around 85$0^{\circ}C$ at the heating rate of 1$0^{\circ}C$/min. It is considered that the solid state sintering at low temperature range should occur as a result of the sintering of Cu phase between aggregates. The specimen was fully densified over 98% for theoretical density at 120$0^{\circ}C$ for 1 h with the heating rate of 1$0^{\circ}C$/min.

• Corrosion Science and Technology
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• v.21 no.4
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• pp.250-257
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• 2022

Transition metal sulfide materials have emerged as a new anode material for Li secondary batteries owing to their high capacity and rate capability facilitated by fast Li-ion transport through the layered structure. Among these materials, niobium disulfide (NbS₂) has attracted much attention with its high electrical conductivity and high theoretical capacity (683 mAh g^-1). In this study, we propose a facile synthesis of Fe_xNbS₂/C composite via simple ball milling and heat treatment. The starting materials of FeS and Nb were reacted in the first milling step and transformed into an Fe-Nb-S composite. In the second milling step, activated carbon was incorporated and the sulfide was crystallized into Fe_xNbS₂ by heat treatment. The prepared materials were characterized by X-ray diffraction, electron spectroscopies, and X-ray photoelectron spectroscopy. The electrochemical test results reveal that the synthesized Fe_xNbS₂/C composite electrode demonstrates a high reversible capacity of more than 600 mAh g^-1, stable cycling stability, and excellent rate performance for Li-ion battery anodes.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.3 no.1
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• pp.28-37
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• 2004

An on-line monitoring system of endmill failure such as weal, chipping, and fracture is developed using AE, cutting force Characteristic variations of AE and cutting force signals due to endmill failure are identified as follows. When endmill fracture occurs, AE count rate shows a rapid Increase in conjunction with a subsequent decrease while a standard deviation of the principal cutting force Increases significantly. The increase of AE count rate precedes the Increase of standard deviation of principal cutting force. Chipping results in relatively small increase and decrease of AE count rate without any significant variation of the cutting force Gradual increase of AE count rate and mean principal cutting force are Identified to be related with the wear of cutter. A cutter fracture detection algorithm is developed based on the present results. The signals me normalized to enhance the applicability of the algorithm to Wide those of fresh cutters, and qualitative characteristics of AE signals encountered at the moment of fracture are employed. It is demonstrated that the algorithm can detect the cutter fracture successfully.

• Journal of Sericultural and Entomological Science
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• v.33 no.1
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• pp.9-12
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• 1991

A study on dyeing-rate for single and mixture dyeing of silk with acid dyes was carried out. Single and mixture dyeings were performed with levelling and milling dyes at 7$0^{\circ}C$ and at pH 3, pH 4 and pH 5, respectively. The results of this study were summerized as follows : 1. C. I. Acid Orange 7. A) At pH 3, dyeing-rate was more fast in the single dyeing than in mixture dyeing at the beginning of dyeing process. B) At pH 4 and 5, dyeing-rates tend to get very similar in single and mixture dyeing. 2. C. I. Acid Blue 138 A) At all pH value, dyeing-rates were more fast in the mixture dyeing than single dyeing at the beginning of dyeing. B) As the time increased, the difference of dyeing-rate and adsorption amounts between single and mixture dyeing was not shown.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.40 no.4
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• pp.512-517
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• 1995

Effects of nitrogen top-dressing method on quality of barley were evaluted over amount of 2 and 4 kg per 10a on volcanic ash soil in Japan under regrowth stage, productive tiller stage and heading stage. 55% milling time was longer by the amount of top- dressing, but that was not influenced by the times of top-dressing. And glassiness, whiteness, hardness and 8 minute- millng rate were not influenced by times and amounts of top-dressing. Crude protein rate of grain was increased by amount of nitrogen top-dressing, but that did not correlated with time of nitrogen top-dressing. Crude protein rate of grain was positively correlated with 55% milling time. But that did not correlated with whiteness of 8 minute-milled grain. 8 minute-milling rate was negatively correlated with whiteness of 8 minute-milled grain. There was no visible difference of protein matrix with scanning electron microscope in different nitrogen levels.