• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.1276-1279
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• 2005

The long-term stability of pentacene thin-film transistors (TFTs) encapsulated with a transparent $SnO_2$ thin-film prepared by ion beam assisted deposition (IBAD) was investigated. With a buffer layer of thermally evaporated 100 nm $SnO_2$ film deposited prior to IBAD process, our encapsulated OTFTs sustained its initial field-effect mobility up to one month and then gradually degraded showing only 37% reduction compared to 90% reduction of non-encapsulated OTFTs after 100 days in air ambient. The encapsulated OTFTs also exhibited superior on/off current ratio of over $10^5$ to that of the unprotected devices $({\sim}10^4)$ which was reduced from ${\sim}10^6$ before aging. Therefore, the enhanced long-term stability of our encapsulated OTFTs should be attributed to well protection of permeation of $H_2O$ and $O_2$ into the devices by the IBAD $SnO_2$ thin-film which could be used as an effective inorganic gas barrier for transparent organic electronic devices.

• The Journal of Advanced Prosthodontics
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• v.8 no.4
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• pp.251-258
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• 2016

PURPOSE. This study was undertaken to investigate whether use of an adhesive penetration enhancer, dimethyl sulfoxide (DMSO), improves bond stability of fiber posts to root dentin using two two-step etch-and-rinse resin cements. MATERIALS AND METHODS. Forty human maxillary central incisor roots were randomly divided into 4 groups after endodontic treatment and post space preparation, based on the fiber post/cement used with and without DMSO pretreatment. Acid-etched root dentin was treated with 5% DMSO aqueous solution for 60 seconds or with distilled water (control) prior to the application of Excite DSC/Variolink II or One-Step Plus/Duolink for post cementation. After micro-slicing the bonded root dentin, push-out bond strength (P-OBS) test was performed immediately or after 1-year of water storage in each group. Data were analyzed using three-way ANOVA and Student's t-test (${\alpha}$=.05). RESULTS. A significant effect of time, DMSO treatment, and treatment${\times}$time interaction were observed (P<.001). DMSO did not affect immediate bonding of the two cements. Aging significantly reduced P-OBS in control groups (P<.001), while in DMSO-treated groups, no difference in P-OBS was observed after aging (P>.05). CONCLUSION. DMSO-wet bonding might be a beneficial method in preserving the stability of resin-dentin bond strength over time when fiber post is cemented with the tested etch-and-rinse adhesive cements.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.513-516
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• 2017

When stored for long periods in a powder-based device (PMD), the explosive power in the device is aged and the explosive power is changed. Thus, The gunpowder used in the PMD must be chemically and physically stable for both internal and external factors. Since $BKNO_3$ and THPP are used as representative gunpowder, thermodynamic and kinetic analyzes were performed based on these gunpowders. Differential scanning calorimeter (DSC) was used to analyze the calorific value and reaction rate. As a result, there was no significant change in caloric value and reaction rate in THPP. In addition, XPS and TEM-EDS analyzes were performed to confirm the formation of oxide films directly related to aging, and no oxide films were observed as a result of thermal analysis. In addition, XPS and TEM-EDS analyzes were performed to confirm the formation of oxide films directly related to aging. As a results, no oxide films were observed. It can be concluded that THPP is the most famous gunpowder in terms of long-term stability.

• Journal of Digital Convergence
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• v.16 no.5
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• pp.361-372
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• 2018

The purpose of this study was to develop an assessment scale for healthy aging of middle aged women. The data were collected from 385 middle aged women in two large cities in Korea. The development processes of the scale were followed: Development of preliminary items; Verification of content validity and reliability; Factor analysis and criterion validity of final items. Results: Factor analysis resulted in the creation of the final scale, which consisted of 38 items that were grouped into 9 factors: self achievement, physical change adaptation, psychological change adaptation, interpersonal relationships, menopausal symptom adaptation, economic stability, physical health, social support, social change adaptation. The explanatory variance was 64.03%. The reliability of the scale was Cronbach's ${\alpha}=.90$. Correlation of the scale with healthy aging and depression, established its construct and concurrent validity was r=-.69, p<.001. The scale was confirmed to have a relatively high validity and reliability. The findings of the study can be useful as a measurement to evaluate healthy aging of middle aged women. Future researches with the scale will be helpful for basic data for the program development to support healthy aging of middle aged women.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.8
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• pp.5452-5457
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• 2015

Conjugating a phytochemical, a strong antioxidant, with a functional peptide not only compensates for its stability, but also improves its solubility and anti-wrinkle effects, thereby contributing to the possibility of becoming an excellent cosmetic ingredient. Thus, in this study we examined the potential cosmetic use of a phytochemical-peptide derivative using gallic acid, a phytochemical with antioxidant, anti-inflammatory, and anti-cancer effects. To evaluate the antioxidant and wrinkle-improving efficacy of 5 synthesized gallic acids conjugated with LVH, IVH, KTTKS, YGGFM, and YGGFLRKYP respectively, we observed the expression of genes related to wrinkle improvement using DPPH radical scavenging activity and real-time PCR. As a result, all 5 derivatives had excellent free radical scavenging effects. The expression level of genes involved collagen synthesis also increased, and the secreted peptides during collagen production contributed to their antioxidant and wrinkle improving effects. These results mark the potential use of gallic acid peptide derivatives as a cosmetic ingredient for anti-oxidation and wrinkle improvement.

• The Journal of Advanced Prosthodontics
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• v.15 no.5
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• pp.227-237
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• 2023

PURPOSE. This study aimed to assess and compare the color stability, flexural strength (FS), and surface roughness of occlusal splints fabricated from heat-cured acrylic resin, milled polymethyl methacrylate (PMMA)-based resin, and 3D-printed (PMMA) based-resin. MATERIALS AND METHODS. Samples of each type of resin were obtained, and baseline measurements of color and surface roughness were recorded. The specimens were divided into three groups (n = 10) and subjected to distinct aging protocols: thermomechanical cycling (TMC), simulated brushing (SB), and control (without aging). Final assessments of color and surface roughness and three-point bending test (ODM100; Odeme) were conducted, and data were statistically analyzed (2-way ANOVA, Tukey, P <.05). RESULTS. Across all resin types, the most significant increase in surface roughness (Ra) was observed after TMC (P < .05), with the 3D-printed resin exhibiting the lowest Ra (P < .05). After brushing, milled resin displayed the highest Ra (P < .05) and greater color alteration (∆E₀₀) compared to 3D-printed resin. The most substantial ∆E₀₀ was recorded after brushing for all resins, except for heat-cured resin subjected to TMC. Regardless of aging, milled resin exhibited the highest FS (P < .05), except when compared to 3D-printed resin subjected to TMC. Heat-cured resin exposed to TMC demonstrated the lowest FS, different (P < .05) from the control. Under control conditions, milled resin exhibited the highest FS, different (P < .05) from the brushed group. 3D-printed resin subjected to TMC displayed the highest FS (P < .05). CONCLUSION. Among the tested resins, 3D-printed resin demonstrated superior longevity, characterized by minimal surface roughness and color alterations. Aging had a negligible impact on its mechanical properties.

• Restorative Dentistry and Endodontics
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• v.33 no.4
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• pp.389-396
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• 2008

The purpose of this study was to evaluate the color stability of resin cements with accelerated test. Four dual curing resin cements: Panavia-F (KURARAY). Duolink (BISCO), Variolink-II (Ivoclar Vivadent), and RelyX Unicem (3M ESPE) and 1 self curing resin cement: Resiment CE (j. l. Blosser) were used in this study. In control group, Gradia Anterior (GC) composite resin and Tescera Dentin (Bisco) indirect composite were used. Ten disk shape specimens were made from each resin cement. The specimens were subjected to an accelerated aging process in a refrigerated bath circulator at 60$^{\circ}C$ for 15 and 30 days. Spectrophotometric analyses were made before and after 15 days and 30 days of accelerated aging time. The color characteristics ($L^*,\;a^*,\;b^*$) and the color difference (${\Delta}E^*$) of the specimens before and after immersion were measured and computed. Regardless of type of the resin cements, $L^*$ value was decreased and $a^*$ value was increased, but there were no significant difference. But $b^*$ value was increased significantly (p < 0.05). Tescera inlay showed least color change (p < 0.05), but Gradia showed notable color change after 15 days. After 30 days on accelerated aging, ${\Delta}E^*$ value was increased (Panavia-F < Variolink-II < Resiment CE < Duolink < Unicem) (p < 0.05). but there were no significant difference among Panavia-F, Variolink-II, and Resiment CE groups. After 30 days of accelerated aging, ${\Delta}E^*$ value of all resin cements were greater than 3.0 and could be perceived by the human eye.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.32 no.6
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• pp.516-523
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• 2020

Since the aging of coastal structures have been increased, the researches about the reinforcements of the existing aged structures are needed. Especially, the existing armor units placed on rubble mound structures should satisfy the stability against the increased design wave conditions. However the researches about these design problems have not been performed. In this study, the hydraulic model tests to investigate the stability number about the additionally placed armor unit were conducted. The main armor unit is a Tetrapod. The test results showed that the stability number (Kd) for additionally placed armor units(Tetrapod) increased up to maximum 10% comparing with that for 2 layers tetrapod (Kd = 8) within these test conditions with the pattern placing for existing armor layers and the stable armor layer slope for the non overtopping condition.

• Journal of the Korean Society of Industry Convergence
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• v.27 no.1
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• pp.229-237
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• 2024

The logistics industry is converging with digital technology and growing into various logistics automation systems. However, inspection and loading/unloading, which are mainly performed in logistics work, depend on human resources, and the workforce is shrinking due to the decline in the productive population due to the low birth rate and aging. Although much research is being conducted on the development of automated logistics systems to solve these problems, there is a lack of research and development on load stacking stability, which has the potential to cause significant accidents. In this study, loading boxes with various sizes and positions of the center of gravity were set up, and a method for stacking that with high stability is presented. The size of the loading box is measured using a depth camera. The loading box's weight and center of gravity are measured and estimated by a developed device with four loadcells. The measurement error is measured through various repeated experiments and is corrected using the least squares method. The robot arm performs load stacking by determining the target position so that the centers of gravity of the loading boxes with unbalanced masses with a random sequence are transported in alignment. All processes were automated, and the results were verified by experimentally confirming load stacking stability.

• Journal of the Korean Operations Research and Management Science Society
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• v.42 no.1
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• pp.29-41
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• 2017

Korea is expected to become a super-aged society by 2050. Given an aging population and the increasing pressure for the early retirement, a sufficient social safety net for elderly population becomes important. The Korean government introduced public reverse mortgage program in 2007, which is a product for aging seniors and the elderly, The number of reverse mortgage subscribers has also steadily grown. The demand continues to grow, but the reverse mortgage over a long period of time is a highly uncertain and risky product in the position of guarantee or lending institution. Thus, suitable demand prediction of the reverse mortgage subscribers is necessary for stable and sustainable operation. This study uses a Bass diffusion model to forecast the long-term demand for reverse mortgage and provides insight into reverse mortgage by forecasting demand for stability and substantiality of the loan product. We represent the projections of new subscribers on the basis of the data obtained from Korea Housing Finance Corporation. Results show that potential market size of Korean reverse mortgage reaches approximately 760,000-1,160,000 households by 2020. We validate the results by comparing the estimate of the cumulative number of subscribers with that found in literature.