• 소성∙가공
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• 제23권8호
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• pp.507-512
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• 2014

The objective of the current investigation is to establish techniques in micro pattern forming operations of polymeric circular tubes by using hydrostatic pressing. This method was developed and successfully applied to the micro pattern forming on polymeric plates. The key idea of the new technique is to pressurize multiple vacuum-packed substrate-mold stacks above the glass transition temperature of the polymeric substrates. The new process is thought to be a promising micro-pattern fabrication technique for two reasons; first, (hydro-) isostatic pressing ensures a uniform micro-pattern replicating condition regardless of the substrate area and thickness. Second, multiple curved substrates can be patterned at the same time. With the prototype forming machine for the new process, micro prismatic array patterns, 25um in height and 90 degrees in apex angle, were successfully made on the PMMA circular tubes with diameters of 5~40mm. These results show that this process can be also used in the micro pattern forming process on curved plates such as circular tube.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.515-518
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• 2001

In this study, the electric door lock using the password input system for security improvement was fabricated. The security has been improved by using the multiple micro process. The controller with solenoid valve has been designed indirect driving system for releasing the door lock system. Also, the self checkup system for improving the trustworthy was developed with two kinds of micro process. The results will be applied IC card system and fingerprint identification system for security improvement.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 추계학술대회 논문집
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• pp.267-270
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• 2009

In the present investigation, we are newly developing a new forming process which can fabricate micro patterns on large-area polymeric substrates for high speed mass production. The key idea of the new process is to pressurize multiple vacuum-packed substrate-mold stacks above the glass transition temperature ($T_g$) of the polymeric substrates. The new process is thought to be promising micro-pattern fabrication technique in three aspects; firstly, isostatic pressing ensures the uniform micro-pattern replicating condition regardless of the substrate area. Secondly, the control of forming condition such as temperature and pressure can realize well-defined process condition exploited in the conventional hot embossing research field. Thirdly, multiple substrates can be patterned at the same time. A prototype forming machine for the new process was developed with the design consideration realizing the present idea. With a developed machine, micro prismatic array patterns with 50 um in size were successfully made on the $380{\times}300{\times}6\;mm$ PMMA plate.

• 산업기술연구
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• 제39권1호
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• pp.33-39
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• 2019

This paper addresses effects of nanoscale structures on structural colors of micropatterned transparent substrate by light diffraction. Structural colors is widely investigated because they present colors without any chemical pigments. Typically structural colors is presented by diffraction of light on a micropatterned surface or by multiple interference of light on a surface containing a periodic or quasi-periodic nano-structures. In this paper, each structural colors induced by quasi-periodic nano-structures, periodic micro-structures, and nano/micro dual structures is measured in order to investigate effects of nanoscale and microscale structures on structural colors in the transparent substrate. Using pre-fabricated pattern mold and hot-embossing process, nanoscale and microscale structures are replicated on the transparent PMMA(Poly methyl methacrylate) substrate. Nanoscale and microscale pattern molds are prepared by anodic oxidation process of aluminum sheet and by reactive ion etching process of silicon wafer, respectively. Structural colors are captured by digital camera, and their optical transmittance spectrum are measured by UV/visible spectrometer. From experimental results, we found that nano-structures provide monotonic colors by multiple interference, and micro-structures induce iridescent colors by diffraction of light. Structural colors is permanent and unchangeable, thus it can be used in various application field such as security, color filter and so on.

• 한국기계가공학회지
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• 제11권1호
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• pp.62-67
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• 2012

Recently UV laser is widely used to process micro parts using various materials such as polymers, metals and ceramics because it has a very high intensity at the focused spot area. It is generally known that there are still some difficulties for alumina($Al_2O_3$) ceramics to directly make micro patterns like holes and lines on the surface of working material using 355nm UV laser because the alumina has a very low absorption coefficient at that wavelength. But nowadays new alumna with nano-porous holes is developed and applied to advanced micro functional parts of IT, BT and BT industries. In this paper, we are going to show the mechanism of photo-thermal ablation for nano-porous ceramics. Inside hole there is a lot of multiple reflections along the depth of hole. Experimentally we can find the micro hole drilling and micro grooving on the surface of nano-porous alumina.

• 대한기계학회논문집A
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• 제24권10호
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• pp.2520-2528
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• 2000

Mechanical and physical properties of composite materials make a great difference due to their cure process condition. In order to clarify the effect of cure process condition on the microscopic damage behavior and failure mechanism of Carbon/Epoxy composites, three point bend test has been performed. For this purpose, two kinds of specimens with single adhesive and multiple adhesive layers were prepared. For single adhesive layer, four different types of specimen were used, that is, non-sanding, sanding, cocured, laminated specimens. Three different types of specimen were also used for the multiple adhesive layer, non-sanding, sanding, cocured specimens. Acoustic emission technique has also been employed to monitor the damage progresses associated with each micro-failure mechanism. The characteristics of AE parameters associated with micro-failure mechanism of each specimen were discussed.

• Structural Engineering and Mechanics
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• 제61권2호
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• pp.193-207
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• 2017

In this study, the vibration of an electrostatically actuated micro cantilever beam is analyzed in which a viscoelastic layer covers a portion of the micro beam length. This proposed model is considered as the main element of mass and pollutant micro sensors. The nonlinear motion equation is extracted by means of Hamilton principle, considering nonlinear shortening effect for Euler-Bernoulli beam. The non-linear effects of electrostatic excitation, geometry and inertia have been taken into account. The viscoelastic model is assumed as Kelvin-Voigt model. The motion equation is discretized by Galerkin approach. The linear free vibration mode shapes of non-uniform micro beam i.e. the linear mode shape of the system by considering the geometric and inertia effects of viscoelastic layer, have been employed as comparison function in the process of the motion equation discretization. The discretized equation of motion is solved by the use of multiple scale method of perturbation theory and the results are compared with the results of numerical Runge-Kutta approach. The frequency response variations for different lengths and thicknesses of the viscoelastic layer have been founded. The results indicate that if a constant volume of viscoelastic layer is to be deposited on the micro beam for mass or gas sensor applications, then a modified configuration may be found by using the analysis of this paper.

• BMB Reports
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• 제51권2호
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• pp.65-72
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• 2018

The endothelial to mesenchymal transition (EndMT) is a newly recognized, fundamental biological process involved in development and tissue regeneration, as well as pathological processes such as the complications of diabetes, fibrosis and pulmonary arterial hypertension. The EndMT process is tightly controlled by diverse signaling networks, similar to the epithelial to mesenchymal transition. Accumulating evidence suggests that microRNAs (miRNAs) are key regulators of this network, with the capacity to target multiple messenger RNAs involved in the EndMT process as well as in the regulation of disease progression. Thus, it is highly important to understand the molecular basis of miRNA control of EndMT. This review highlights the current fund of knowledge regarding the known links between miRNAs and the EndMT process, with a focus on the mechanism that regulates associated signaling pathways and discusses the potential for the EndMT as a therapeutic target to treat many diseases.

• 한국전기전자재료학회논문지
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• 제27권10호
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• pp.623-629
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• 2014

For the semiconductor device safety from over current in the digital electronic circuit system must be surely designed that it's surface mount type micro fuse device. In this paper, We has analysed to the fusing character of micro fuse as a function changed thickness of thermosetting ink epoxy. To the change of thermosetting ink epoxy thickness with in production lot, in the electrically character (fusing test in the 2 multiple over current and 10 multiple over current, surface temperature test in the 1.25 multiple over current) of micro fuse has been tested. According to the electrically character result, changed thickness of thermosetting ink epoxy in designed micro fuse withheld direct effect in both end resistance changes. Also, because high thermal energy in the micro fuse test of over current was occurred to effect such as thermal runaway and explosion. Therefore, screen printing process in the design of micro fuse using thermosetting ink epoxy is very important for production quality improvement.

• 한국정밀공학회지
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• 제24권12호
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• pp.128-135
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• 2007

Micro-channels for a wave micropump have been fabricated using the Stereolithography and UV Photolithography. The micro-channel with a channel height of $500\;{\mu}m$ was fabricated with stereolithography. UV photolithography was used for producing micro-channels with a channel length less than $100\;{\mu}m$. The fabrication process data including spinning rpm, pre-bake and post-bake time, and develop time for single layer and multiple layer 3D micro-structures using SU-8 photo resist are experimentally found. A film mask printed with a 40,000 dpi laser printer was used for UV lithography and micro-structures in the order of tens of micrometers in dimension were successfully fabricated.