• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.1
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• pp.216-221
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• 2017

Reducing optical reflection in the visible light range, in order to increase the share of transmitted light and avoid the formation of ghost images in imaging, is important for polymer lens applications. In this study, polymer lenses with refractive indices of n=1.56, 1.60, and 1.67 were fabricated by the injection-molding method with a polymer lens monomer, dibutyltin dichloride as the catalyst and an alkyl phosphoric ester as the release agent. To investigate their anti-reflection (AR) effects, various AR coating structures, viz. a multi-layer AR coating structure, tri-layer AR coating structure with a discrete approximation Gaussian gradient-index profile, and tri-layer AR coating structure with a quarter-wavelength approximation, were designed and coated on the polymer lens by an E-beam evaporation system. The optical properties of the polymer lenses were characterized by UV-visible spectrometry. The material properties of the thin films, refractive index and surface roughness, were analyzed by ellipsometry and AFM, respectively. The most effective AR coating structure of the polymer lens with low refractive index, n=1.56, was the both side coating of multi-layer AR coating structure. However, both side coating of the tri-layered discrete approximation Gaussian gradient-index profile AR coating structure gave comparable results to the both side coating of the multi-layer AR coating structure for the polymer lens with a high refractive index of n=1.67.

• Design & Manufacturing
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• v.15 no.2
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• pp.11-16
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• 2021

Recently, three-dimensional (3D) cell culture systems, which are superior to conventional two-dimensional (2D) vascular systems that mimic the in vivo environment, are being actively studied to reproduce drug responses and cell differentiation in organisms. Conventional two-dimensional cell culture methods (scaffold-based and non-scaffold-based) have a limited cell growth rate because the culture cannot supply the culture medium as consistently as microvessels. To solve this problem, we would like to propose a 3D culture system with an environment similar to living cells by continuously supplying the culture medium to the bottom of the 3D cell support. The 3D culture system is a structure in which microvascular structures are combined under a scaffold (agar, collagen, etc.) where cells can settle and grow. First, we have manufactured molds for the formation of four types of microvessel-mimicking chips: width / height ①100 ㎛ / 100 ㎛, ②100 ㎛ / 50 ㎛, ③ 150 ㎛ / 100 ㎛, and ④ 200 ㎛ / 100 ㎛. By injection molding, four types of microfluidic chips were made with GPPS (general purpose polystyrene), and a 100㎛-thick PDMS (polydimethylsiloxane) film was attached to the top of each microfluidic chip. As a result of observing the flow of the culture medium in the microchannel, it was confirmed that when the aspect ratio (height/width) of the microchannel is 1.5 or more, the fluid flows from the inlet to the outlet without a backflow phenomenon. In addition, the culture efficiency experiments of colorectal cancer cells (SW490) were performed in a 3D culture system in which PDMS films with different pore diameters (1/25/45 ㎛) were combined on a microfluidic chip. As a result, it was found that the cell growth rate increased up to 1.3 times and the cell death rate decreased by 71% as a result of the 3D culture system having a hole membrane with a diameter of 10 ㎛ or more compared to the conventional commercial. Based on the results of this study, it is possible to expand and build various 3D cell culture systems that can maximize cell culture efficiency by cell type by adjusting the shape of the microchannel, the size of the film hole, and the flow rate of the inlet.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.4
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• pp.1807-1812
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• 2014

A plastic has a various advantages in engineering elements that it can be formed a curve surface without restriction of shape and product the high volume with various color and lower price. Also, it is being used for many parts of automobile as the weight of cars is getting lighter. The Door A-Fuel Filler is a automobile plastic part by injection molding production. The injected products are involved a lot of factors for the inferior goods after painting. Therefore the painted products are required to have the process of the polishing in order to eliminate the faults. Now polishing process is being worked by hands. The workers tend to evade the process of polishing because the working needs a lot of powers momentarily. This paper presents the development of auto-polishing system that can check the inferior goods by the vision system and control the polishing process by the motion system. As a result, Shorten production time (30 seconds), and decreases by 1 person to work to increase the competitiveness of the production cost was to expect improvement.

• Journal of Powder Materials
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• v.22 no.3
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• pp.197-202
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• 2015

In this study, porous stainless steel (STS316L) sintered body was fabricated by powder metallurgy method and its properties such as porosity, compressive yield strength, hardness, and permeability were evaluated. 67.5Fe-17Cr- 13Ni-2.5Mo (wt%) powder was produced by a water atomization. The atomized powder was classified into size with under $45{\mu}m$ and over $180{\mu}m$, and then they were compacted with various pressures and sintered at $1210^{\circ}C$ for 1 h in a vacuum atmosphere. The porosities of sintered bodies could be obtained in range of 20~53% by controlling the compaction pressure. Compressive yield strength and hardness were achieved up to 268 MPa and 94 Shore D, respectively. Air permeability was obtained up to $79l/min{\cdot}cm^2$. As a result, mechanical properties and air permeability of the optimized porous body having a porosity of 25~40% were very superior to that of Al alloy.

• Journal of Korea Foundry Society
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• v.14 no.5
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• pp.471-479
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• 1994

Al-2%Si-2%Mg alloy containing SiC particle in 20, $70{\mu}m$ were prepared by mean of squeeze casting with various pressure 50, 100, 150 and 220MPa respectively. The specimens were made by casting into $50{\Phi}{\times}100{\ell}$ mold under various squeeze conditions(pressures, pressurizing temperature, particle sizes). Mechanical properties(hardness, tensile strength, elongation and wear characteristics) were evaluated at room temperature with those various fabrication factors. It became feasible to make favorable Al-SiCp composite free from casting defects by the injection of Ar gas during melting and 100MPa pressure squeeze casting. However, pressure of 50MPa was not sufficient to avoid completely porosity formation as a result of precessing and shrinkage during solidification. As the particle size is smaller and the squeeze pressure is higher, the hardness and tensile strength at room temperature are higher. Cell size became smaller gradually with increase of squeeze pressure. With increase of squeeze pressure(MPa), wear behaviors of those composites were changed from adhesive into abrasive wear, and the tendency of above behavior became outstanding with increasing sliding speed. The chemical reaction(4Al＋3SiC${\rightarrow}$$Al_4C_3+3Si$) is more accelerated at interface between SiCp and matrix with increase of squeeze pressure. Therefore $Al_4C_3$ intercompound and Si peak intensity is increased at interface.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.3
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• pp.1241-1246
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• 2014

Take-out robots used for handling of the plastic parts manufactured with the injection mold are usually the gantry type that consists of long and thin links. In this study, we want to evaluate the safety of the take-out Robot structure through finite element analysis. The take-out Robot is automated robot to transport from one location to another in the molded article. The take-out Robot structure has a 380 kilogram weight, a 1300mm width, a 670.5mm depth and a 670mm height. It confirms the equivalent stress and the deformation of the load and its own weight through weight analysis. It looks for the natural frequency of the take-out robot through modal analysis. It confirms the acceleration, the normal stress and the deformation about the natural frequency of the take-out robot through response analysis. Also It repeats the analysis by changing the structure of the take-out robot, to confirm the results and it is determined whether the safety of the structure. These analysis results are effectively used to reduce the vibration of the take-out robot.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.6
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• pp.117-124
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• 2017

In this study, we investigated the optimization of process conditions by using the Six Sigma process, design of experiment (DOE) method and response surface method (RSM) to resolve dimensional deviation and appearance problems arising from the shortened process time of the mobile phone rear cover. The analysis of the trivial many was performed by 2-sample T-test and cooling time, and mold temperature and packing pressure were selected as the vital fews affecting the overall width of the product. The optimal conditions of the process were then studied using the DOE and the RSM. We analyzed the improvement effects by applying the selected optimal conditions to the production process and the results showed that the difference between the mean value and target value of the overall width stood at 0.01 mm, an improvement of 88.89% compared to current process that fell within the range of standard dimension. The short-term process capability stood at $4.77{\sigma}$, which implied an excellent technology level despite a decrease by $0.22{\sigma}$ compared to the current process. The difference in process capability decreased by $2.44{\sigma}$ to $0.41{\sigma}$, showing a significant improvement in management capability. Ultimately, the process time of the product was shortened from 18.3 seconds in the current process to 13.65 seconds, resulting in a 34.07% improvement in production yield.

• Laser Solutions
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• v.6 no.3
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• pp.19-28
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• 2003

The manufacturing process for the microfluidic device can include sequential steps such as master fabrication, electroforming, and injection molding. The laser ablation, using masks, has been applied to the fabrication of channels in microfluidic devices. In this research, an excimer laser was used to engrave microscopic channels on the surface of PET (polyethylene terephthalate), which shows a high absorption ratio for an excimer laser beam with a wavelength of 248 m. When 50-${\mu}{\textrm}{m}$-wide rectangular microscopic channels are ablated with a 500 ${\times}$ 500 ${\mu}{\textrm}{m}$ square mask at a magnification ratio of 1/10, ditch-shaped defects were found in both corners. The measurement of laser beam intensity showed that a coherent image in the PET target caused such defects. Analysis based on the Fourier diffraction theory enabled the prediction of the coherent shape at the image surface as well as the diffraction beam shape between the mask and the image surface. It also showed that the diameter of the aperture had a dominant effect. The application of aperture with a diameter of less than 3 mm helped to eliminate such defects in the ablated rectangular microscopic channels on PET without such ditch-shaped defects.

• Design & Manufacturing
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• v.17 no.1
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• pp.48-55
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• 2023

In this study, on the structure simulation for manufacturing a high strength/light weight 48V battery housing for a mild hybrid vehicle was conducted. Compression analysis was performed in accordance with the international safety standards(ECE R100) for existing battery housings. The effect of plastic materials on compressive strength was analyzed. Three models of truss, honeycomb and grid rib for the battery housing were designed and the strength characteristics of the proposed models were analyzed through nonlinear buckling analysis. The effects of the previous existing rib, double-sided grid rib, double-sided honeycomb rib and double-sided grid rib with a subtractive draft for the upper cover on the compressive strength in each axial direction were examined. It was confirmed that the truss rib reinforcement of the battery housing was very effective compared to the existing model and it was also confirmed that the rib of the upper cover had no significant effect. In the results of individual 3-axis compression analysis, the compression load in the lateral long axis direction was the least and this result was found to be very important to achieve the overall goal in designing the battery housing. To reduce the weight of the presented battery housing model, the cell molding method was applied. It was confirmed that it was very effective in reducing injection pressure, clamping force and weight.

• Design & Manufacturing
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• v.18 no.2
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• pp.57-63
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• 2024

In this study, the recyclability of commonly used PP (polypropylene) and ABS (acrylonitrile butadiene styrene) was evaluated by molding test specimens from mixture of virgin and shredded material, followed by measuring their strength properties, Experiments were conducted o two type of PP (transparent and non-transparent) and two types of ABS (white and yellow). Test specimens for each resin were prepared with shredded material ratios ranging from 10% to 50% in 10% increments. Changes in tensile strength, elastic modulus, and elastic limit were analyzed based on the mixing ratio of the shredded material. The experimental results demonstrated that the strength properties of all the resins remained consistent within a certain range, even with increasing proportions of shredded material. For transparent PP, the tensile strength ranged from 30.87± MPa, the elastic modulus from 1.23±0.04 GPa, and the elastic limit from 19.17±0.44%. Non-transparent PP exhibited a tensile strength ranging from 27.71±0.58 MPa, an elastic modulus from 1.03±0.06 GPa, and an elastic limit from 17.35±0.41%. For ABS, white ABS had a tensile strength of 39.42±0.28 MPa, an elastic modulus of 1.94±0.01 GPa, and an elastic limit of 36.76±0.25%. Yellow ABS showed a tensile strength of 39.25±0.78 MPa, an elastic modulus of 1.94±0.01 GPa, and an elastic limit of 37.14±0.23%, with values remaining consistent within this range. Based on these results, it was confirmed that the mechanical properties of the resins used in this study do not change significantly when mixed with recycled shredded material, indicating excellent mechanical recyclability.