• Journal of Mechanical Science and Technology
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• v.19 no.5
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• pp.1065-1071
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• 2005

In this study, residual stress distribution in multi-stacked film by MEMS (Micro-Electro Mechanical System) process is predicted using Finite Element method (FEM). We evelop a finite element program for residual stress analysis (RESA) in multi-stacked film. The RESA predicts the distribution of residual stress field in multi-stacked film. Curvatures of multi­stacked film and single layers which consist of the multi-stacked film are used as the input to the RESA. To measure those curvatures is easier than to measure a distribution of residual stress. To verify the RESA, mean stresses and stress gradients of single and multi layers are measured. The mean stresses are calculated from curvatures of deposited wafer by using Stoney's equation. The stress gradients are calculated from the vertical deflection at the end of cantilever beam. To measure the mean stress of each layer in multi-stacked film, we measure the curvature of wafer with the left film after etching layer by layer in multi-stacked film.

• Transactions of Materials Processing
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• v.20 no.3
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• pp.250-256
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• 2011

Vacuum-assisted thermoforming is one of the critical steps for the successful application of film insert molding(FIM) to parts of complex shapes. If the thickness distribution of the formed film is non-uniform, cracking, deformation, warping, and wrinkling can easily occur at the injection molding stage. In this study, the effects of processing parameters, which include the film heating time, plug depth, plug speed and vacuum delay time, on film thickness distribution were investigated. It was found that the film thickness at the part sidewall decreases with increasing the film heating time and plug depth, but the thickness at the bottom was found to exhibit the opposite behavior. The film thickness of the sidewall was observed to increase at higher plug speed and vacuum delay time of 0 ~ 0.3sec.

• International Journal of Industrial Entomology and Biomaterials
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• v.27 no.2
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• pp.312-316
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• 2013

Caffeine is a thermogenic agent that can be used in weight loss products. In order to achieve a sustained release of caffeine, silk fibroin (SF) film was uses as carrier. It has been shown that the loading method of caffeine into SF film affected the uniform distribution of caffeine in the SF film. When caffeine was added directly into SF solution, gelation has been occurred immediately and prevented the uniform distribution of caffeine. On the other hand, caffeine was dissolved in methanol in order to load the caffeine in SF film and crystallize the SF film at the same time. However, due to the fast evaporation of methanol, caffeine was recrystallized on the surface of SF film rather than penetrating into the film. Finally, caffeine was loaded into pre-crystallized SF film and uniform distribution of caffeine could be achieved. There was an initial burst of caffeine during the first 15 min, but after that a sustained release was achieved.

• Nuclear Engineering and Technology
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• v.54 no.10
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• pp.3811-3815
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• 2022

Ni-63 is pure beta source which emits low energy beta particles. The Ni-63 sources were fabricated to develop the beta-voltaic battery which converts decay energy into electrical energy for power generation. Activity distribution of the source was important factor of power producibility of the beta-voltaic battery. Liquid scintillation counter widely used for measurement of low energy beta emitters was not suitable to measure activity distribution. In this study, we used the peeled-off Gafchromic™ EBT3 film to measure the activity distribution of the Ni-63 source. Absorbed dose was increased proportionally to the source activity and exposure duration. The low energy beta particles could transport the energy into the active layer without the polyester protective layer. Also, Activity distribution was measured by using the peeled-off EBT3 film. Two-dimensional dosimetric distribution was suitable to measure the activity distribution. To use the peeled-off EBT3 film is user-friendly and cost-effective method for quality assurance of the Ni-63 sources for the beta-voltaic battery.

• Korean Journal of Medicinal Crop Science
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• v.28 no.2
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• pp.152-166
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• 2020

Background: Ginsenosides, which have various physiological activities, are known to be abundant in the leaves and roots of ginseng. Ginseng sprouts can be used as a fresh vegetable and roots, stems, and leaves of ginseng can be consumed. This study aimed to investigate the effect of carbon dioxide treatment and the modified atmosphere (MA) packaging method in suppressing quality deterioration during the distribution of ginseng sprouts. Methods and Results: Ginseng sprouts were packed using Styrofoam, barrier film + non gas treatment, barrier film + gas treatment, 15 ㎛ polyamide (PA) double film + non gas treatment, 15 ㎛ PA double film + gas treatment, 25 ㎛ PA film + non gas treatment, or 25 ㎛ PA film + gas treatment. Quality parameters including gas composition, relative humidity, chlorophyll SPAD (Soil Plant Analysis Development) value, firmness, and rate of quality loss in ginseng sprouts were monitored at the following temperatures: 20℃, and 10℃. Ginseng sprouts packaged with 25 ㎛ PA film showed loss in quality because of wilting owing to low relative humidity within the film. Chlorophyll and firmness did not differ between film and gas treatments. The time point at which the combined loss from softening and decay owing to fungal, and bacterial infection and wilt reached 20% was considered the limit of distribution. At 20℃, the packaging not included in the 20% distribution loss rate limit or up to 7 days was 15 ㎛ PA double film + gas treatment. At 10℃, the packaging not included in the 20% distribution loss rate limit for up to 18 days were barrier film + gas treatment and 15 ㎛ PA double film + gas treatment. Conclusions: The film packaging suitable for the distribution of ginseng sprouts was found to be the barrier film and PA film with low gas permeability and maintaining hygroscopicity at 95% relative humidity. To prevent the loss in quality of ginseng sprouts, gas treatment (8% of O₂ and 18% of CO₂) in the film was found to be more suitable than no gas treatment for inhibition of decay.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.05a
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• pp.281-284
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• 2008

Film insert melding is one of the surface processes that enhances functional or aesthetic qualities of an existing product's surface. In general, film insert molding consists of three processes including thermoforming, trimming and injection molding. Thermoforming, which is the first process of film insert molding, is the most important process because the variation of film thickness has an effect on the mold design and process conditions for the subsequent processes, that are, trimming and injection molding. This study is focused on predicting the film thickness distribution through film insert thermoforming process using commercial FEM code. In order to describe rheological behavior of thermoplastic film (ABS), G'Sell's viscoelastic constitutive law was adopted. The numerical model of film insert thermoforming was established, and the simulation to predict film thickness distribution was performed. Comparison between the results of simulation and experiment was made to validate the proposed finite element analysis.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.1262-1265
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• 2004

To increase the performance of the light diffusion films, we controlled the three dimensional microstructure of the organic fillers(beads). The refractive index, the size distribution and the three dimensional distribution of beads play an important role to determine the performance of light diffusion films for the backlight unit of TFT-LCD.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1991.06a
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• pp.50-54
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• 1991

This paper shows the effect of axial profile on the elastohydrodnamic lubrication (EHL) behavior of axially profiled cylindrical roller. For two different type of profiles which have nearly similar elastostatic pressure distribution, the EHL results show large differences. Especially the difference in film shape is larger than that of pressure distribution. Therefore, the magnitude of the minimum film thickness should be a major criteria to design the axial profile of the roller and a new design procedure is presented which take into account the minimum film thickness as well as the pressure distribution.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.260-262
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• 2002

An accurate measurement of dose distribution is indispensable to perform radiation therapy planning. A measurement technique using a radiographic film, which is called a film dosimetry, is widely used because it is easy to obtain a dose distribution with a good special resolution. In this study, we tried to develop an analyzing system for the film dosimetry using usual office automation equipments such as a personal computer and an image scanner. A film was sandwiched between two solid water phantom blocks (30 ${\times}$ 30 ${\times}$ 15cm). The film was exposed with Cobalt-60 ${\gamma}$-ray whose beam axis was parallel to the film surface. The density distribution on the exposed film was stored in a personal computer through an image scanner (8bits) and the film density was shown as the digital value with NIH-image software. Isodose curves were obtained from the relationship between the digital value and the absorbed dose calculated from percentage depth dose and absorbed dose at the reference point. The isodose curves were also obtained using an Isodose plotter, for reference. The measurements were carried out for 31cGy (exposure time: 120seconds) and 80cGy (exposure time: 300seconds) at the reference point. While the isodose curves obtained with our system were drawn up to 60% dose range for the case of 80cGy, the isodose curves could be drawn up to 80% dose range for the case of 31cGy. Furthermore, the isodose curves almost agreed with that obtained with the isodose plotter in low dose range. However, further improvement of our system is necessary in high dose range.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.6
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• pp.134-140
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• 2003

The film sensor is used for measuring pressure distribution at planar area, especially at a small space or gap. The present paper deals with the development of film type sensors and system for pressure distribution measuring. The developed system is consist of (1)film sensor with 40/sup */40 array, (2)PCI interface card with maximum sampling rate of 100㎐, and (3)software for data processing and real-time display. The contact pressure test of wiper blade and front glass of vehicle was performed with wiper blade by 40cm. Generally spring force of wiper arm is designed at 0.7∼1kN. Test results of total force was 9.4N and 7.1N in each driver and passenger toward. The paper suggested possibility for base definition in wiper design. A windshield wiper blade experiment revealed that the system successfully measured the contact force distribution during static state, showing the usefulness of the developed system.