• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.05a
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• pp.270-274
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• 2005

The capability of net shaping for complex 3-D geometry, powder injection molding(PIM) is widely used for parts in the field of automotives, electronics and medical industry. Powder injection mold design for dental scaler tip, a component of medical appliance, was presented. In comparison with conventional machining process, powder injection molding has many advantages, specially in price and dimensional stability, for molding dental scaler tip. Product design and mold design for dental scaler tip was presented. Short shot experiment with scaler tip PIM mold and several defect (flash etc.) during injection molding process was discussed.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.05a
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• pp.450-453
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• 2008

During the drawing of reentrant section like a spline, the unfilled in the corner of dies or the bended product emerges from the large reduction of area, the complex shaped sections and other nonuniform properties in material and lubrication conditions. In this study, the drawing of the spline section with the non-rotary symmetry from a circular aluminum billet has been analyzed by using commercial code DEFORM-3D. A new die construction method preventing the spline from the drawback of bending and the unfilled defect has been suggested and verified through the analysis using centroid shift method and the hybrid construction between converged and diverged profile.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.9
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• pp.89-95
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• 1999

The compression behavior of semi-solid materials in studied from a viewpoint of yield criteria and analysis methods. To describe the behavior of materials in semi-solid state, several theories have been proposed by extending the concept of plasticity of porous compressible materials. in the present work, the upper-bound method and the finite element method are used to model the simple compression process using yield criteria of Kuhn and Doraivelu. Segregation between solid and liquid which cause defect of product is analysed for Sn-15%Pb alloy is compared with the experimental result of Charreyron et al..

• Journal of Korea Multimedia Society
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• v.24 no.8
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• pp.988-999
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• 2021

AOI (Automatic Optical Inspection) of PCB (Printed Circuit Board) is a very important step to guarantee the product performance. The process of registering components called teaching mode is first perform, and AOI is then carried out in a testing mode that checks defects, such as recognizing and comparing the component mounted on the PCB to the stored components. Since most of registration of the components on the PCB is done manually, it takes a lot of time and there are many problems caused by mistakes or misjudgement. In this paper, A components classifier is proposed using YOLO (You Only Look Once) v2's object detection model that can automatically register components in teaching modes to reduce dramatically time and mistakes. The network of YOLO is modified to classify small objects, and the number of anchor boxes was increased from 9 to 15 to classify various types and sizes. Experimental results show that the proposed method has a good performance with 99.86% accuracy.

• Journal of Construction Engineering and Project Management
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• v.4 no.2
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• pp.12-22
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• 2014

Over the last decade, Saudi Arabia has experienced significant economic increases as evidenced by the 30% growth in its gross domestic product; furthermore, the construction industry has increased 10% in the same time period. Due to this significant growth, the construction industry is encountering issues related to construction quality resulting in significant waste and associated environmental impacts. In this research, we applied our previously developed framework that integrates three different methods-Lean, Green, and Six-sigma - to a residential construction complex in Saudi Arabia. Our aim of this case study was to explore the application of the framework in practice to glean quantitative results and further validate the framework. In the case study, we used the developed framework to identify a significant issue related to quality and delays - final completion of 53 residential units was delayed because of failed exterior buildings surfaces. We then used the framework to define the causes behind the defects via a field investigation of the 53 units. Of the defect, construction execution was responsible for 43% of the defect, 31% untrained workers, 19% unfavorable construction weather condition, with 7% accounting for other issues. A procedure was developed in concert with the construction manager and overall developer reducing the amount of rework and waste causes revealed by the field examination and the framework. Although two steps were added to the original construction process to overcome waste causes, still save a lot of resources and reduces environmental impact. In summary, we found that the Lean, Green, Six-sigma framework increased productivity, quality, and reduced waste.

• Journal of Microbiology and Biotechnology
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• v.16 no.1
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• pp.84-91
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• 2006

A Saccharomyces cerevisiae pgs1 nulI mutant, which is deficient with phosphatidyl glycerol (PG) and cardiolipin (CL) biosynthesis, grows well on most fermentable carbon sources, but fails to grow on non-fermentable carbon sources such as glycerol, ethanol, and lactate. This mutant also cannot grow on galactose medium as the sole carbon source. We found that the incorporation of $[^{14}C]-galactose$, which is the first step of the galactose metabolic pathway (Leloir pathway), into the pgs 1 null mutant cell was extremely repressed. Exogenously expressed PGS1 (YCpPGS1) under indigenous promoter could completely restore the pgs1 growth defect on non-fermentable carbon sources, and dramatically recovered $[^{14}C]-galactose$ incorporation into the pgs1 mutant cell. However, PGS1 expression under the GALl promoter $(YEpP_{GAL1}-PGS1myc)$ could not complement pgs1 mutation, and the GAL2-lacZ fusion gene $(YEpP_{GAL2}-lacZ)$ also did not exhibit its $\beta-galactosidase$ activity in the pgs1 mutant. In wild-type yeast, antimycin $A(1\;{\mu}g/ml)$, which inhibits mitochondrial complex III, severely repressed not only the expression of the GAL2-lacZ fusion gene, but also uptake of $[^{14}C]-galactose$. However, exogenously expressed PGS1 partially relieved these inhibitory effects of antimycin A in both the pgs1 mutant and wild-type yeast, although it could not basically restore the growth defect on galactose by antimycin A. These results suggest that the PGSI gene product has an important role in utilization of galactose by Gal genes, and that intact mitochondrial function with PGS1 should be required for galactose incorporation into the Leloir pathway. The PGS1 gene might provide a clue to resolve the historic issue about the incapability of galactose with deteriorated mitochondrial function.

• Journal of Powder Materials
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• v.21 no.3
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• pp.215-221
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• 2014

Translucent alumina is a potential candidate for high temperature application as a replacement of the glass or polymer. Recently, due to the increasing demand of high power light emitting diode (LED), there is a growing interest in the translucent alumina. Since the translucent property is very sensitive to the internal defect, such as voids inside or abnormal grain growth of sintered alumina, it is important to fabricate the defect-free product through the fabrication process. Powder injection molding (PIM) has been commonly applied for the fabrication of complex shaped products. Among the many parameters of PIM, the flowability of powder/binder mixture becomes more significant especially for the shape of the cavity with thin thickness. Two different positions of the gate were applied during PIM using the disc type of die. The binder was removed by solvent extraction method and the brown compact was sintered at $1750^{\circ}C$ for 3 hours in a vacuum. The flowability was also simulated using moldflow (MPI 6.0) with two different types of gate. The effect of the flowability of powder/binder mixture on the microstructure of the sintered specimen was studied with the analysis of the simulation result.

• Journal of Digital Policy
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• v.2 no.4
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• pp.17-23
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• 2023

In this paper, in order to improve production processing for small and medium-sized precision processing companies, we apply a manufacturing execution system to existing process methods and integrate precision processing data to strengthen process management within the company, increase facility operation efficiency, and realize a reduction in defect rates. The differences in productivity improvement and cost reduction rates were compared and analyzed. As a result, production productivity improved by 7.0% and product defect rate improved by 0.1% point due to the introduction of the manufacturing execution system. It was confirmed that manufacturing cost reduction improved by 10.0% and delivery compliance rate improved by 1.1%. If additional smart factory technology is applied based on the manufacturing execution system proposed in this study in the future, sales and profits in the processing industry are expected to increase due to an increase in the PQCD index.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.6
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• pp.482-489
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• 2020

This study conducted a prototype development and evaluation by performing die-casting mold design, mold manufacturing, and injection condition optimization based on flow and solidification analysis to meet the needs of the coupling parts produced by die casting. Through flow analysis, the injection conditions suitable for 100% filling in the cavity were found to be a molten metal temperature of 670 ℃, injection speed of 1.164 m/s, and filling pressure of 6.324~18.77 MPa. In addition, solidification close to 100 % occurred in all four cavities when the solidification rate was 69.47 %. A defect inspection on the surface and inside the product revealed defects, such as poor molding and pores. In addition, the dimensions of the injected product were within the target tolerance and showed good results. Through the feedback of the results of flow and solidification analysis, it was possible to optimize the mold design, and the injection optimization conditions were confirmed to be a total cycle time of approximately 6.5 seconds. Good quality carrier parts with an average surface hardness of approximately 45 mm from the gate measured at 97.48(Hv) could be produced.

• Journal of Convergence Society for SMB
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• v.1 no.1
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• pp.19-28
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• 2011

In today and near future, most of the commercially manufactured IT products will be evolved into software convergence product. Recently, the embedded software products is called as 'Software Convergence Products.' This phenomenon does not simply show the trendy fashion, but has the seriously implication that the functionalities of IT product is accomplished and evolved via software technology, not via mechanical nor electrical means. It will become true that the quality of the convergence product is dominantly governed by the software it uses. Meanwhile, we are facing with the threatening fact that software defects in the mass products will requires tremendous amounts of cost proportional to the quantity of the product. We can remind ourselves of the disasters that have been already happened, such as Automotive recalls, Smart-phone recalls, and others. In software engineering, there have been large amount of work done in software quality improvement for the past couple of decades. Software process improvement, and testings are the representative ones. But we are facing with limitations of those traditional approaches in current convergence industry; exponentially increasing software sizes and rapid changes in software technology. In this paper, we analyze the characteristics of the software convergence industry, the limitations of the traditional Software quality improvement approaches. We suggest a new approaches in software quality improvement in different angles of thought and philosophy.