• Journal of the Korean Society for Precision Engineering
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• v.16 no.2 s.95
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• pp.234-243
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• 1999

Using the geometric and the vector methods, three dimensional surface texture and roughness models in flat end milling are developed. In these models, rear cutting effect on surface generation is considered along with tool run-out and tool setting error including tool tilting and eccentricity between tool center and spindle rotational center. Rear cutting is the secondary cutting of the already machined surface by the trailing cutting edge. The effects of tool geometry and tool deflection on surface roughness are also considered. For representing the surface texture more practically, three dimentional surface topography parameters such as RMS deviaiton, skewness and kurtosis are introduced and used in expressing the surface texture characteristics. Under various cutting conditions, it is confirmed that the developed models predict the real surface profile precisely. These models could contribute to the cutter design and cutting condition selection for the reduction of machining and manual finishing time.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.11
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• pp.64-70
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• 2003

This paper suggests a systematic methodology to predict chip forms using the experimental design technique and the neural network. Significant factors determined with ANOVA analysis are used as input variables of the neural network back-propagation algorithm. It has been shown that cutting conditions and cutting tool shapes have distinct effects on the chip forms, so chip breaking. Cutting tools are represented using the Z-map method, which differs from existing methods using some chip breaker parameters. After training the neural network with selected input variables, chip forms are predicted and compared with original chip forms obtained from experiments under same input conditions, showing that chip forms are same at all conditions. To verify the suggested model, one tool not used in training the model is chosen and input to the model. Under various cutting conditions, predicted chip forms agree well with those obtained from cutting experiments. The suggested method could reduce the cost and time significantly in designing cutting tools as well as replacing the“trial-and-error”design method.

• The korean journal of orthodontics
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• v.46 no.6
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• pp.386-394
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• 2016

Objective: The objective of the study was to evaluate the practicality and the validity of different surface treatments of self-drilling orthodontic mini-implants (OMIs) by comparing bone cutting capacity and osseointegration. Methods: Self-drilling OMIs were surface-treated in three ways: Acid etched (Etched), resorbable blasting media (RBM), partially resorbabla balsting media (Hybrid). We compared the bone cutting capacity by measuring insertion depths into artificial bone (polyurethane foam). To compare osseointegration, OMIs were placed in the tibia of 25 rabbits and the removal torque value was measured at 1, 2, 4, and 8 weeks after placement. The specimens were analyzed by optical microscopy, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS). Results: The bone cutting capacity of the etched and hybrid group was lower than the machined (control) group, and was most inhibited in the RBM group (p < 0.05). At 4 weeks, the removal torque in the machined group was significantly decreased (p < 0.05), but was increased in the etched group (p < 0.05). In the hybrid group, the removal torque significantly increased at 2 weeks, and was the highest among all measured values at 8 weeks (p < 0.05). The infiltration of bone-like tissue surface was evaluated by SEM, and calcium and phosphorus were detected via EDS only in the hybrid group. Conclusions: Partial RBM surface treatment (hybrid type in this study) produced the most stable self-drilling OMIs, without a corresponding reduction in bone cutting capacity.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.40 no.2
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• pp.57-64
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• 2008

In general, the entire of paper mulberry bark, which is not cut into pieces with an appropriate length, have been used in the pulping. This kind of pulping method couldn't accomplish the improvement of beating and sheet forming efficiency. For this reason, we investigated the effects of the cutting length of paper mulberry bast fiber on pulping and Hanji (Korean traditional paper) properties, in order to develop high quality Hanji manufacturing process. The cutting length variation of paper mulberry white bast did not great effects on pulp yields. The pulp yields based on pulping methods were sulfomethylated pulping av. 57.4%, alkali-hydrogen peroxide pulping av. 55.4%, and alkaline pulping av. 53.5% respectively. The optical properties such as brightness, opacity, scattering coefficient, and absorption coefficient were slightly improved by the increase of paper mulberry white bast cutting length. The increase of paper mulberry white bast cutting length resulted in poor sheet formation. Physical properties such as breaking length, TEA, tear index, burst index, and folding endurance were slightly improved by the increase of cutting length. The modified pulping processes, which used sulfomethylated method and alkali-hydrogen peroxide method, showed better pulp and sheet properties than conventional alkaline pulping.

• Journal of Power System Engineering
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• v.20 no.5
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• pp.5-13
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• 2016

This study is on wear damage of the material for a molding machine that be used at finally cutting of metal beam made in roll forming process of vehicle bump beam process line. SKD11 steel was used with the material for cutting mold jig. In the cutting mold jig, Ti diffusion heat treatment after vacuum heat treatment was carried out for upgrade of surface hardness and anti-wear. Also, the heat treatments by various methods were performed to compare the wear damage degree against above the existing heat treatment. Wear loss and friction coefficient were obtained from wear test. And, micro Vickers hardness values were compared with damaged parts or not of cutting mold jig. Micro Vickers hardness value appeared higher at the undamaged part by Ti diffusion heat treatment. The micro Vickers hardness well followed a two-parameter Weibull probability distribution.

• 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.

• Korean Journal of Microbiology
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• v.44 no.1
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• pp.22-28
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• 2008

Cutting oils are emulsionable fluids widely used in metal working processes. Their composition is mineral oil, water, and additives (fatty acids, surfactants, biocides, etc.) generating a toxic waste after a long use. Cutting oils also affect colour, taste and odour of water, making it undesirable for domestic and industrial uses. In these days, conventional treatment methods as evaporation, membrane separation or chemical separation have major disadvantages since they generate a concentrated stream that is more harmful than the original waste. In this study, our purpose is to reduce cutting oils by using biological treatment. Eighty one strains were isolated from cutting waste oil of industrial waste water sludge under aerobic conditions. Among these strains, KS47, which removed 90.4% cutting oil in 48 hr, was obtained by screening test under aerobic conditions(pH 7, $28^{\circ}C$). KS47 was identified as Pseudomonas aeruginosa according to morphological, physiological and biochemical properties, 16S rDNA sequence, and fatty acid analysis. P. aeruginosa KS47 could utilize cutting oil as carbon source. In batch test, we obtained optimal degradation conditions(1.5 g/L cell concentration, pH 7, and temperature $30^{\circ}C$). Under the optimal conditions, 1,060 mg/L cutting oil was removed 83.7% (74.1 mg/L/hr).

• Journal of Bio-Environment Control
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• v.17 no.4
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• pp.252-260
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• 2008

This study was conducted to observe the characteristics of mineral nutrient uptake of single-node cutting rose 'Versilla' and to determine optimal nutrient solution control method for soilless culture of 'Versilla' in a closed hydroponic system. Nutrient solution was managed by five different control methods: macro- and micro-element control in aeroponic system (M&M), macroelement control in aeroponic system (M), nutrient solution supplement in aeroponic system (S); electrical conductivity (EC) control in aeroponic system(EC-A); EC control in deep flow technique system(EC-D). The concentration of $NO_3$-N exceeds optimal range whereas P and Mg decreased at the later stage of plant growth with the EC control method, EC-A and EC-D. The overall mineral nutrient content increased with S. On the other hand the nutrient content at the root environment was maintained optimal with M&M and M. The nutrient solution control methods had significantly effect on the cut-flower quality. In the M&M and M, flower length, fresh weight and root activity were higher than those with the other mineral nutrients control methods. The maximal efficiency of photochemistry (Fv/Fm) was higher for M&M, M and S than that with EC-A and EC-D. Based on the above results, it is highly recommended to control nutrient solution by mineral nutrient control methods (M&M and M) in a closed hydroponic system for single-node cutting rose, 'Versillia'.

• Korean Journal of Computational Design and Engineering
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• v.1 no.1
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• pp.45-55
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• 1996

This paper presents a new approach to non-parametric modeling of cutter swept surface (CSS) for cutting simulation. Instead of explicitly modeling cutter swept volumes, silhouette curves of the cutter surface are utilized in computing the z-value of the CSS at a grid point on the x,y-plane. The non-parametric evaluation of the CSS constitutes the integral part of 3-axis cutting simulation. The proposed method is more efficient than the existing ones in the case of conventional cutters (i.e., ball-end mills and flat-end mills), and more importantly, it enables the non-parametric modeling of the CSS for the round-end mills which was not possible with the existing methods.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.5
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• pp.47-56
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• 2003

Geometric cutting-simulation and verification play an important role in detecting NC machining errors in mold & die manufacturing and thereby reducing correcting time & cost on the shop floor. Current researches in the area may be categorized into view-based, solid-based, and discrete vector-based methods mainly depending on workpiece models. Each methodology has its own strengths and weaknesses in terms of computing speed, representation accuracy, and its ability of numerical inspection. The paper proposes a hybrid modeling scheme for workpiece representation with z-map model and discrete vector model, which performs 3-axis and 5-axis cutting-simulation via tool swept surface construction by connecting a sequence of silhouette curves.