• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.23 no.3
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• pp.291-298
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• 2014

This study uses two numerical approaches to analyze the filling behavior of micro patterns on micro-injection molding for V-grooves pattern which cannot be simulated with conventional CAE packages. The parametric studies have been performed to examine the fidelity of micro patterns with respect to temperature, pressure, inlet velocity and pattern location on the mold according to the boundary condition from the macro pressure and velocity data which can be obtained by conventional CAE packages. Through these numerical approaches, the filling behavior of polymer melt in micro patterns can be understood, the quality of replication can be predicted, and the V-groove pattern can be shaped uniformly during the process of injection molding.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.3
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• pp.218-223
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• 2009

The micro pattern machining on the surface of wide mold is not easy to be simulated by conventional software. In this paper, a software is developed for micro pattern cutting simulation. The 3d geometry of v-groove, rectangular groove, pyramid and pillar patterns are visualized by C++ and OpenGL library. The micro cutting force is also simulated for each pattern.

• Design & Manufacturing
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• v.10 no.3
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• pp.25-29
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• 2016

Recently, a hyaluronic acid micro needle patch for therapeutic and cosmetic purposes has been used by attaching directly to the skin with a pattern having a micro needle shape of 1/3 thickness of hair. These products are attracting attention as an innovative product that maximizes the effect by activating the active ingredient in the skin in the deep skin without blocking the horny layer because the micro needle shape exists on the patch surface so that it can penetrate effectively to the skin. Currently, DAB (droplet air blowing) or MEMS technology is used to make pattern shapes for patches. Because of this technology, manufacturing time is long and manufacturing cost is high, so we tried to develop the mold technology to machine the microneedle shape directly to the metal. In this study, we first fabricated a needle pattern with a quadrangular pyramid shape and finally produced a conical needle pattern.

• Design & Manufacturing
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• v.12 no.1
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• pp.47-51
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• 2018

As the IT industry rapidly progresses, the functions of electronic devices and display devices are integrated with high density, and the model is changed in a short period of time. To implement the integration technology, a uniform micro-pattern implementation technique to drive and control the product is required. The most important technology for the micro pattern generation is the exposure processing technology. Failure to implement the basic pattern in this process cannot satisfy the demands in the manufacturing field. In addition, the conventional exposure method of the mask method cannot cope with the small-scale production of various types of products, and it is not possible to implement a micro-pattern, so an alternative technology must be secured. In this study, the technology to implement the required micro-pattern in semiconductor processing is presented through the photolithography process and plasma etching.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.10 no.2
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• pp.110-116
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• 2011

The current study investigated the friction property of angle and width effect for micro-scale grooved crosshatch pattern on SKD11 steel surface against bearing steel using pin-on-disk type. The samples fabricated by photolithography process and then these are carry out the electrochemical etching process. We discuss the friction property due to the influence of a hatched-angle and a width of groove on contact surface. We could be explained the lubrication mechanism for a Stribeck curve. So It was found that the friction coefficient depend on an angle of the crosshatch on contact surface. It was thus verified that micro-scale crosshatch grooved pattern could affect the friction reduction. Also, it is play an important a width of groove to be improved the friction property. I was found that friction property has a relationship between a width and an angle for micro-grooved pattern.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.272-273
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• 2013

Some living thingsuse micro- or nano- structures for living in nature. Scientists and engineers made efforts to mimic them, and they succeeded in making new types of applications. They used 'Namib desert beetle' to self-filling device by moisture harvesting and 'lotus leaf' to self-cleaning device by water repelling. 'Namib desert beetle' and lotus leaf have micro-patterns on their surface, which consists of hydrophobic or hydrophilic materials [1]. Moreover, micro-patterns on the surface make self-filling or self-cleaning property enhanced because of the surface roughness. Surface roughness enhances wettability [2]. Micro-pattern is a significant factor to make the surface be functional, so we want to make new types of functional surface by micro-patterning. In this work,we make several functional micro-patterns (radial, line, and dot arrays) using maskless lithography and analyze the characteristics of each micro-pattern. In order to analyze and understand surface characteristics, micro-patterns with varying sizes are investigated. All experiments are proceeded on mr-DWL5 photo resists coated on silicon wafers in same condition. All the experiments have demonstrated good performances about hydrophobic or hydrophilic property corresponding to their material and structural combinations. In radial micro-pattern, although the surface is flat, water drops on hydrophilic radial pattern can be convergent to a middle point and water drops on hydrophobic radial pattern can be divergent from the middle point. In line array micro-pattern, water drops can roll off along only one direction in parallel with the line arrays. Such phenomena might be mainly caused by the local change of surface roughness. From these results, controlling the movement and direction of water drops is made feasible without introducing a slope, which can potentially be used for new types of applications.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.18 no.3
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• pp.307-314
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• 2009

Large area micro pattern replication has promising application potential in many areas. Rolling imprint process has been demonstrated as one of the most competitive processes for such micro pattern replication, because it has advantages in low cost, high throughput and high efficiency. In this paper, we developed a prototype of roll-to-flat(R2F) thermal imprint system for large area micro pattern replication process, which is one of the key processes in the fabrication of flexible displays. Experimental tests were conducted to evaluate the feasibility of system and the parameters' effect on the process, such as flat mold temperature, loading pressure and rolling speed. 100mm $\times$ 100mm stainless steel flat mold and commercially available polycarbonate sheets were used for the tests. The experimental results showed that the developed R2F system is suitable for fabrication of various micro devices with micro pattern over large area.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.549-550
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• 2006

It has become topic continuously at MEMS or semiconductor process to form three-dimensional multilayer structure. In this paper, we devised the new polymer pattern method that has multilayer structure. This is method that uses different kind of polymeric material. Specially, polymers used in this study that we propose became all pattern by photolithography, prevented that process increases. Here, polymer that we use used polymer of epoxy order called "SU-8" and polymer of novolak resin called "AZ-1518". The result, "SU-8" was formed pattern to 3.5um thickness, and "AZ-1518" about pattern 3um thickness. Also, It was been 6um thickness at same pattern area.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.533-534
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• 2006

Micro pyramid pattern and its array are designed to enhance the brightness and its uniformity of LGP which is one of key parts in LCD. The designed micro pyramid patterns are fabricated on a Si-wafer first through MEMS process and then a Ni-stamper is electro-plated from the Si pattern master. Adopting the fabricated Ni-stamper, LGPs are injection molded at different mold temperatures and the fidelity of the pattern replication is estimated for each molding conditions and pattern locations. The replicated patterns are found to have some defect such as local short shot or micro weld line which are believed to have negative effect on the performance of the LGP.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.2
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• pp.188-193
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• 2005

Surface texturing of tribological application is another attractive technology of friction reducing. Also, reduction of friction is therefore considered to be a necessary requirement for improved efficiency of machine. In this paper attempts to investigate the effect of density for micro-scale dimple pattern on bearing steel flat mated with pin-on-disk. We demonstrated the lubrication mechanism for a Stribeck curve, which has a relationship between the friction coefficient and a dimensionless parameter for lubrication condition. It is found that friction coefficient is depended on the density of surface pattern. It was thus verified that micro-scale dimple could affect the friction reduction considerably under mixed and hydrodynamic lubrication conditions from based on friction map. Lubrication condition regime has an influence on the friction coefficient induced the density of micro dimple.