• Design & Manufacturing
• /
• v.2 no.6
• /
• pp.38-42
• /
• 2008

Recently, the demands of digital camera and miniature camera module for mobile-phone is increased significantly. Lenses which is the core component of optical products are made by the injection molding(plastic lens) or GMP(glass lens). Plastic lens is not enough to improve the resolution and performance of optic parts. Therefore, the requirement of glass lens is increased because it is possible to ensure the high performance and resolution. In this paper, the thermal stress analysis of 3 cavity GMP mold for molding glass lens was performed for estimating the thermal stress and amount of deformation. Finally, the modification plan based on the analysis results was deducted.

• Journal of the Korean Applied Science and Technology
• /
• v.4 no.2
• /
• pp.31-34
• /
• 1987

Effect of initial PH on the lipid accumulation and fatty acid composition of some species of mold were investigated. The maximum lipid content content produced by Aspergillus niger var. macrosporus was 17.5% at PH 3.5, by Aspergillus fumigatus 23.5% at PH 3.5 by Penicillium spinulosum 12.0% at PH 4.0 and by Penicillium notatum 7.3% at PH 4.0. The major fatty acids were palmitic, stearic, oleic and linoleic acid in all experimental molds. At PH from 4.5 to 6.0, the proportion of linoleic acid was increased and those of palmitic and oleic acid were decreased with rising in PH, therefore, degree of lipid unsaturation was increased in all experimental molds.

• Design & Manufacturing
• /
• v.7 no.1
• /
• pp.19-22
• /
• 2013

Almost all injection molds have multi-cavity runner system for mass production, which are designed with geometrically balanced runner system in order to accomplish filling balance between cavity to cavity during processing. However, even though geometrically balanced runner is used, filling imbalances have been observed. So, many studies for improving filling balance in the multi-cavities molds are worked up. In this study, the Melt-Buffer which is a new runner system for filling balance has been suggested, and a series of experiment about degree of filling balance in cavity-to-cavity was conducted in the mold with the Melt-Buffer. From the experiment, the filling balance was increased up to 5~6% by using the Melt-Buffer.

• Design & Manufacturing
• /
• v.8 no.2
• /
• pp.41-45
• /
• 2014

Automated polishing apparatus based on the research have been developed. The research is improvement of polishing process for surface quality and uniformity improvement of preform injection mold core. Surface quality of preform core have influence on ejecting and product quality after injection molding. Thus, the current being made by hand to automate the polishing process, the surface of the preform to improve the quality and uniformity improvement. First made a division by analyzing manual process a step-by-step. And draw a mechanism for converting mechanical movement. Automated polishing apparatus for preform core was developed, through which shortens production time and were able to secure the safety of the worker.

• The Korean Journal of Ecology
• /
• v.21 no.4
• /
• pp.351-355
• /
• 1998

This study was carried out to investigate occurrence and distribution of cellular slime molds by vegetation in Mt. Seorak. Eleven species were isolated from surface soil samples as follows: P. violaceum, P. candidum, P. purpureum, D. brefeldianum, D. minutum, D. delicatm, D. crassicaule, D. macrocephalum, D. firmibasis, D. polycephalum and D. implicatum. The dorminant species was D. brefeldinum. D. delicatum, D. implicatum, D. polycephalum and P. candidum of them were isolated rarely in Korea. It can be thought that these results were caused by characteristics of forest zone and geographical condition which Mt. Seorak is located at east side of central areas of Korea.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2003.07a
• /
• pp.788-790
• /
• 2003

Closed-cell type barrier ribs of PDP were formed by capillary molding process using molds prepared by inclined UV lithography process. Various types of molds with different inclined angles were prepared by patterning SU-8 thick photoresist film and casting with PDMS. The ribs with various type cells were successfully formed by the process. The effects of inclined angle on the distortion of barrier ribs during sintering were investigated. The results indicated that the barrier ribs with a draft angle and dimensional change does not affect the distortion of the barrier ribs during sintering, suggesting that the closed-cell must be isotropic in sintering shrinkage.

• Journal of the Korean Society for Precision Engineering
• /
• v.21 no.10
• /
• pp.50-56
• /
• 2004

Finishing is the final process in molds manufacturing and consumes much process time. Also, it influences on surface quality of molds. But, there are few systematic methods to control the process. In this work, basic experiments were carried out to study the machining characteristics of the finishing tools. From the experiments, critical surface roughness and wear coefficient are suggested to reduce the number of finishing steps and to plan a systematic finishing procedure. Comparison experiments were carried out between the expert's method and the new method, which is based on the results of this research. From the experiments, it is verified that the systematic method takes less time and generates less form error in the machined surface than the worker's method.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2003.06a
• /
• pp.752-755
• /
• 2003

Injection molding is the one of the most important processes for mass production of plastic parts. Usually Injection molds for mass production are constituted to multi-cavity runner system to manufacture the more parts at a time. To uniformly fill to each cavity, multi-cavity molds are designed to geometrically balanced runner system. However. in practice this is not the case. The previous studies by Beaumount at.[2] reported that filling imbalance occurred by thermal unbalance on the mold and viscosity variation of resins and so on. In this study, we conducted experiments in order to know the causes or filling imbalance for 3 plate type mold with 8 cavities. We presented a new so called 4BF mold(4plate Type Balanced Filling Mold) to improve filling balance. We conducted a experimental injection molding to verify a efficiency of the 4BF mold. In the results of the experiment, We could confirmed the possibility of the 4BF mold.

• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.16 no.5
• /
• pp.63-69
• /
• 2007

The high speed machining has been widely applied to manufacture dies and machine elements in industrial field. Especially, 5-axis milling has been employed to produce a wide range of turbine blades, impellers and complex molds. In this study, the machining characteristics of injection molds were investigated according to tool tilting angles in 5-axis milling. The cutting force and surface roughness were investigated with various tool tilting angles. When the tool tilting angle was over than 10 degree, the characteristics of cutting force and surface roughness were improved in machining of Al alloy.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2000.05a
• /
• pp.1043-1046
• /
• 2000

By combination of X-ray lithography, electroplating and molding process, various microstructures have been produced. Specially, the alignment grooves for multi-fibers with submicron accuracy have been produced. This paper described a fabrication process of LICA molds and micro molding technique by using LIGA molds. The accuracy of the fabricated LIGA molds was less than 0.4${\mu}{\textrm}{m}$. The injection molded alignment grooves were very precise and had me surface roughness so that they could be successfully applicable to optical systems.