• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.32 no.2
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• pp.122-128
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• 2019

Porcelain insulators have been used mainly for power line fixing and electrical insulation in transmission towers. Porcelain insulators have generally a 30 years desired life, but over 50% exceed their life expectancy. Since the damage to porcelain insulators is usually accompanied by enormous loss of human resource material, their efficient maintenance has emerged as an important issue. In this regard, this study applied a frequency response function (FRF) for integrity assessment of the insulator. The characteristics of the FRF according to damage types were identified and analyzed by the change in natural frequencies, curve shape, attenuation, and Nyquist diagram stability. The results showed significant differences in the FRF according to damage types, which can be used as basic data for the effective integrity assessment of porcelain insulators.

• Nuclear Engineering and Technology
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• v.53 no.7
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• pp.2407-2417
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• 2021

A structural integrity evaluation program (STEP) was developed for the high temperature reactor design evaluation according to the ASME Boiler and Pressure Vessel Code (ASME B&PV), Section III, Rules for Construction of Nuclear Facility Components, Division 5, High Temperature Reactors, Subsection HB. The program computerized HBB-3200 (the design by analysis procedures for primary stress intensities in high temperature services) and Appendix T (HBB-T) (the evaluation procedures for strain, creep and fatigue in high temperature services). For evaluation, the material properties and isochronous curves presented in Section II, Part D and HBB-T were computerized for the candidate materials for high temperature reactors. The program computerized the evaluation procedures and the constants for the weldment. The program can generate stress/temperature time histories of various loads and superimpose them for creep damage evaluation. The program increases the efficiency of high temperature reactor design and eliminates human errors due to hand calculations. Comparisons that verified the evaluation results that used the STEP and the direct calculations that used the Excel confirmed that the STEP can perform complex evaluations in an efficient and reliable way. In particular, fatigue and creep damage assessment results are provided to validate the operating conditions with multiple types of cycles.

• The Korea Journal of Herbology
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• v.32 no.3
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• pp.79-87
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• 2017

Objectives : This study aimed to investigate the protective effects of an herbal mixture of Atractylodes macrocephala and Taraxacum spp. (ATC) on ulcerative colitis. We have previously screened traditional medicinal herbs to discover the effective candidate by the animal model. A. macrocephala and T. spp were identified as one of the effective herbs in the screening process. Methods : Experimental colitis was induced in male Balb/c mice by administering drinking water containing dextran sulfate sodium, which mimics the clinical and histological features of ulcerative colitis in human. ATC at doses of 30, 100 or 300 mg/kg were orally administered to mice twice per day for 10 consecutive days. To evaluate the damage from experimentla ulcerative colitis, body weight, colon length, disease activity index, myeloperoxidase and histological changes were measured and analyzed. Results : The administration of dextran sulfate sodium with drinking water resulted in markedly reduced colon length, severe body weight loss, increased levels of myeloperoxidase activity and histological damages in mice. ATC treatment significantly ameliorated the colon shortening, histological damage, body weight loss and disease activity index score in a dose-dependent manner. ATC also attenuated the colonic myeloperoxidase activity which reflects the severity and extent of inflammatory damage of colon. Conclusions : ATC exerts protective effects against inflammatory colonic structural damage induced by epithelial barrier integrity impairment. ATC also inhibits weight loss and related symptoms of UC which can be considered as the functional recovery of colon.

• Steel and Composite Structures
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• v.49 no.4
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• pp.407-417
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• 2023

After a disaster like the catastrophic earthquake, the government have to use rapid assessment of the condition (or damage) of bridges, buildings and other infrastructures is mandatory for rapid feedbacks, rescue and post-event management. Many domain schemes based on the measured vibration computations, including least squares estimation and neural fuzzy logic control, have been studied and found to be effective for online/offline monitoring of structural damage. Traditional strategies require all external stimulus data (input data) which have been measured available, but this may not be the generalized for all structures. In this article, a new method with unknown inputs (excitations) is provided to identify structural matrix such as stiffness, mass, damping and other nonlinear parts, unknown disturbances for example. An analytical solution is thus constructed and presented because the solution in the existing literature has not been available. The goals of this paper are towards access to adequate, safe and affordable housing and basic services, promotion of inclusive and sustainable urbanization and participation, implementation of sustainable and disaster-resilient buildings, sustainable human settlement planning and manage. Simulation results of linear and nonlinear structures show that the proposed method is able to identify structural parameters and their changes due to damage and unknown excitations. Therefore, the goal is believed to achieved in the near future by the ongoing development of AI and control theory.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.2
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• pp.632-638
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• 2018

Recently, damage to waterside structures, such as bridges or retaining walls, is increasing due to typhoons, flooding, aging, etc. In such cases, the damage is not limited to the structures themselves, but can include effects on a wider scale, such as the suspension of and restriction of access to the facilities, human injury, economic loss, etc. To preclude such damage, recovery methods suitable for the particular field circumstances should be applied when damage occurs. By enforcing prompt repairs, the material and human damage and losses that can occur can be minimized. Since the impact of losses caused by damage and disaster increases with the elapse of time, emergency recovery is even more important. In the emergency recovery process, appropriate repair and reinforcement is crucial. In the present study, the derivation scenarios of the emergency recovery method were applied to some field recovery cases, and their applicability was verified by comparison with the recovery methods actually used. It is expected that the results of this study will be useful for practical application, by suggesting more appropriate recovery methods.

• Korean Journal of Human Ecology
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• v.16 no.6
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• pp.1197-1209
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• 2007

The advance of digital contents industry shifts the focus of consumptions; from analogue to digital ones. It gives significant impact on individual life as well as overall society and culture, and it leads to the increased consumption of digital contents. Nevertheless, current digital contents industry fails to secure the sufficient consumer protection systems including relevant rules and laws which regulate the distribution, use, and other transaction activities of digital contents and the efforts, on the part of contents providers, to provide information to consumers and to protect them. Digital contents, by its nature, is different from the existing products so that its nature is likely to cause unique consumer problems totally different from the offline transactions and the electrical transactions of existing products. This study, therefore, aims to identify the possible problems which may be incurred by consumers in their use of digital contents, specify the types of consumer damages, and provide the underlying materials to improve the systems related to digital contents and take legally complementary measures for consumer protection. To identify the types of consumer damages, this study analyzed the results from consumer counselling cases, experts opinion survey, and FGI. For consumer damage cases, this study analyzed the consumer complaints received by open consumer counselling sites of the Korea Consumer Agency and Seoul Electronic Commerce Center. For experts opinion survey, it conducted questionnaire survey of the group of experts from digital contents manufacturers or providers, and those who treated consumer damages directly. For FGI analysis, it organized a panel of students and employees who had used digital contents to understand the types of consumer damages. The results of this study can be summed up as follows. Based on the results from consumer counselling cases, experts opinion survey, and FGI analysis, the consumer damages related to digital contents can be classified, in their nature, into economic or financial damages (25 cases), emotional or psychological ones (15 cases), time-related ones (7 cases), physical ones (4 cases), and privacy-related ones (i.e. leakage of personal data)(3 cases). More specifying the types of damages, damages can be subdivided into contract-, charge-, maintenance-, use-, individual-related ones and other ones. Among them, both contract- and charge-related damages appeared only in the economic or financial damages, whereas user-specific individual damages appeared only in physical and emotional or psychological ones. On the other hand, maintenance- and use-related damages and other ones were observed in both categories of economical or financial damages and time-related ones. Use- and privacy-related damages, in particular, caused emotional or psychological damages.

• Journal of Life Science
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• v.29 no.10
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• pp.1164-1170
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• 2019

The present study was carried out to evaluate extracts of Ginko biloba's outer seed coat, their antioxidative effects, and their ability to protect against DNA damage due to hydrogen peroxide ($H_2O_2$) treatments in cultured human keratinocyte (HaCaT) cells. The bioassays applied for determining the antioxidant effects of a G. biloba outer seed coat water extract (GOSWE) and a G. biloba outer seed coat methanol extract (GOSME) included the DPPH and $H_2O_2$ radical scavenging assays. Our results revealed that GOSME had higher activity than GOSWE against $H_2O_2$ radical scavenging activity in in vitro and in vivo bioassays. Treatment with GOSME significantly increased the viability of $H_2O_2-treated$ HaCaT cells. GOSME's ability to protect against DNA damage was observed via the analysis of plasmids in vitro and genomic DNA in $H_2O_2-treated$ HaCaT cells. According to our data, GOSME is able to protect HaCaT cells from $H_2O_2-induced$ DNA damage and apoptosis by blocking cellular damage related to oxidative stress. In conclusion, our study indicated GOSME might serve as a novel agent for the treatment and prevention of skin disorders caused by oxidative stress.

• Biomolecules & Therapeutics
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• v.32 no.1
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• pp.84-93
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• 2024

Rosmarinic acid (RA) is a phenolic ester that protects human keratinocytes against oxidative damage induced by ultraviolet B (UVB) exposure, however, the mechanisms underlying its effects remain unclear. This study aimed to elucidate the cell signaling mechanisms that regulate the antioxidant activity of RA and confirm its cyto-protective role. To explore the signaling mechanisms, we used the human keratinocyte cell line HaCaT and SKH1 hairless mouse skin. RA enhanced glutamate-cysteine ligase catalytic subunit (GCLC) and glutathione synthetase (GSS) expression in HaCaT cells in a dose- and time-dependent manner. Moreover, RA induced nuclear factor erythroid-2-related factor 2 (NRF2) nuclear translocation and activated the signaling kinases protein kinase B (AKT) and extracellular signal-regulated kinase (ERK). Treatment with the phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002, the ERK inhibitor U0126, and small interfering RNA (siRNA) gene silencing suppressed RA-enhanced GCLC, GSS, and NRF2 expression, respectively. Cell viability tests showed that RA significantly prevented UVB-induced cell viability decrease, whereas the glutathione (GSH) inhibitors buthionine sulfoximine, LY294002, and U0126 significantly reduced this effect. Moreover, RA protected against DNA damage and protein carbonylation, lipid peroxidation, and apoptosis caused by UVB-induced oxidative stress in a concentration-dependent manner in SKH1 hairless mouse skin tissues. These results suggest that RA protects against UVB-induced oxidative damage by activating AKT and ERK signaling to regulate NRF2 signaling and enhance GSH biosynthesis. Thus, RA treatment may be a promising approach to protect the skin from UVB-induced oxidative damage.

• Tunnel and Underground Space
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• v.7 no.4
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• pp.310-322
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• 1997

New limits of comfort boundary, psychological damage boundary and exposure limit for building residents by continuous and vibration are suggested. These limits are derived from the ISO 2631 and DIN 4150 regulations. A reasonable method to evaluate damages by vibrations is also suggested using the "total over-exposure of vibration" concept.; concept.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.42 no.1
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• pp.87-94
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• 2016

Skin damage is mainly caused by environmental factors such as ultraviolet light, heat, and smoking. It is known that reactive oxygen species production is commonly involved in the pathogenesis of skin damage induced by these factors, causing skin aging. Pyrus pyrifolia Nakai continues to be a popular and highly consumed fruit in many countries with known beneficial effects including antitumor, antioxidative, and anti-inflammatory effects. However, there is no evidence of a therapeutic effect of Pyrus pyrifolia extract (PPE) against skin aging via inhibition of mitochondria-mediated apoptosis. In this study, we investigated PPE protective effect against photoaging induced by UVB ($50mJ/cm^2$) in HS68 human dermal fibroblasts. Lactate dehydrogenase assay showed that PPE significantly protected HS68 cells against UVB-induced damage in a dose-dependent manner. Other assays using DCF-DA demonstrated that PPE protected HS68 cells by regulating reactive oxygen species production. PPE also regulated mitochondrial dysfunction and mitochondrial membrane potential induced by UVB, and inhibited UVB-induced caspase-3 activity. These results indicate that PPE protects human dermal fibroblasts from UVB-induced damage by regulating the oxidative defense system.