• The Journal of the Korean dental association
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• v.56 no.4
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• pp.218-230
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• 2018

According to the burst of aged people, researchers have focused on aging-related diseases. Cognitive impairment including Alzheimer's disease (AD), one of the representative diseases related to aging, has no treatment option until now. Recently, it has been revealed that systemic inflammation plays a fundamental role in the pathogenesis of AD. Previous studies have suggested the association between poor oral health and cognitive impairment. Poor oral health can cause dental caries, chronic periodontitis, multiple tooth loss, and poor chewing ability, etc. Especially, periodontitis is a well-known chronic inflammatory disease and affects cognitive impairment directly and indirectly by inflammatory products mediators. Therefore, reduction of pathogenic microbial burden and inflammatory products by treating periodontitis can be a therapeutic modality to prevent cognitive impairment or to slow down the progression of it. Future studies are necessary to elucidate the causal relations and plausible mechanisms between poor oral health and cognitive impairment.

• Journal of Korea Society of Industrial Information Systems
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• v.18 no.1
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• pp.19-24
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• 2013

As CMOS technology is scaled down more aggressively, the reliability mechanism (or aging effect) caused by the diffusion of metal atoms along the conductor in the direction of the electron flow, also called electromigration (EM), has become a major reliability concern. With the present of EM, it is difficult to control the current flows of the MOSFET device and interconnect. In addition, nanoscale CMOS circuits suffer from increased gate leakage current and power consumption. In this paper, the EM effects on current of the nanoscale CMOS circuits are analyzed. Finally, this paper introduces an on-chip current measurement method providing lifetime electromigration management which are designed using 45-nm CMOS predictive technology model.

• Journal of Sensor Science and Technology
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• v.28 no.1
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• pp.17-22
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• 2019

As CMOS technology scales down, reliability is becoming an important concern for VLSI designers. This paper analyzes gate-oxide breakdowns (i.e., the time-dependent dielectric-breakdown (TDDB) aging effect) as a reliability issue for combinational circuits with 45-nm technology. This paper shows simulation results for the noise margin, delay, and power using a single inverter-chain circuit, as well as the International Symposium on Circuits and Systems (ISCAS)'85 benchmark circuits. The delay and power variations in the presence of TDDB are also discussed in the paper. Finally, we propose a novel method to compensate for the logic failure due to dielectric breakdowns: We used a higher supply voltage and a negative ground voltage for the circuit. The proposed method was verified using the ISCAS'85 benchmark circuits.

• Journal of Korea Society of Digital Industry and Information Management
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• v.6 no.1
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• pp.69-81
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• 2010

Physical manifestations of aging due to the lack of exercise include the slowing down of motor learning, cardiopulmonary degradation, and the increasing difficulty to adapt to the environment. Aging is manifested with the lack of aerobic exercise work, decrease in muscular endurance, decline in skeletal and muscular strength, flexibility and agility, and the decrease in reaction speed and balance. Added to those are aging-related physiological changes, including the reduction of muscle bulk, increased body fat, decrease in total body water and basic metabolic rate as activities are reduced, and a decrease in cell and Lean Body Mass (LBM). These changes are known to cause problems. Interest and participation in appropriate physical activities among the elderly is needed to help them increase stamina, avoid diseases, maintain a clear intellect, and basically enable the elderly to live their daily lives as easy as possible. Therefore, physical activities are necessary for the elderly to enhance health-related factors. Special exercises should be performed for the enhancement of muscle function, muscle endurance, flexibility, agility, and balance. An accurate measurement of cardio-respiratory endurance and stamina through basic physical and cognitive characteristics of older adults is also required to ensure safety. Also, the development of a more scientific resistance exercise prescription system for the elderly is desperately needed.

• Journal of the Korean Society of Safety
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• v.15 no.1
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• pp.28-35
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• 2000

As huge energy transfer systems like a nuclear power plant, steam power plant and petrochemical plant are operated for a long time, mechanical properties are changed by degradation. The life time of the systems can be affected by the mechanical properties. So determination of the integrity of the metallic structure is required either to en4sure that failure will not occur during the service life of the components or to evaluate the lifetime extension of the structure. An automated ball indentation(ABI) method was developed as a non-destructive technique for evaluating the integrity of such metallic components. In this paper, we would like to present the aging evaluation technique by the ABI method. The five classes of the thermally aged CF8M specimens were prepared using an artificially accelerated aging method. After holding 100, 300, 900, 1800 and 3600 hours at 43$0^{\circ}C$, the specimens were cooled down using water to room temperature respectively. The tensile test, hardness test, charpy impact test, ABI test were performed. The results of the fracture test were compared with those of ABI test and the new evaluation technique of the integrity of metallic structures was developed.

• Archives of Pharmacal Research
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• v.29 no.2
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• pp.165-171
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• 2006

Osteoarthritis is thought to be induced by the ageing-related loss of homeostatic balance between degeneration and repair mechanism around cartilage tissue in which inflammatory mediators such as reactive oxygen species, cytokines and prostaglandins are prone to overproduction under undesirable physiological conditions. Phlorotannins are unique polyphenolic compounds bearing dibenzo-1,4-dioxin skeleton which are not found in terrestrial plants but found only in some brown algal species such as Ecklonia and Eisenia families. Phlorotanninrich extracts of Ecklonia cava including LAD103 showed significant antioxidant activities such as DPPH radical scavenging, ferric ion reduction, peroxynitrite scavenging, and inhibition of LDL oxidation, indicating their possible antioxidative interference both in onset and downstream consequences of osteoarthritis. LAD103 also showed significant down regulation of $PGE_2$ generation in LPS-treated RAW 246.7 cells, and significant inhibition of human recombinant interleukin-$1{\alpha}$-induced proteoglycan degradation, indicating its beneficial involvement in pathophysiological consequences of osteoarthritis, the mechanism of which needs further investigation. Since LAD103 showed strong therapeutic potentials in arthritic treatment through several in vitro experiments, it is highly encouraged to perform further mechanistic and efficacy studies.

• Journal of Electrical Engineering and Technology
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• v.13 no.2
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• pp.892-901
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• 2018

Because of excellent electrical properties, epoxy resin is widely used in packaging and casting power equipment. Moisture and temperature in the environment are inclined to seriously affect the insulation tolerance of epoxy resin. This work focuses on the aging characteristics of epoxy resin in hygrothermal environment. Scanning electron microscopy images show that there are micro-crack, micro-slit and holes inside aged samples. The moisture absorption process undergoes three equilibrium stages and it does not follow the Fick's second law. Observing the change of hydrogen bonds in the infrared spectra of the dried samples, it is found that chemically moisture absorption immerges when the physical moisture absorption entered the third equilibrium stage. By Debye equation to fit the imaginary part of the dielectric constant, it is concluded that the uniformity of water molecule has a great influence on the electrical conductivity loss. Furthermore, the polarization loss can be more easily affected by water molecules than small free molecules. After the aged samples being dried, their real and imaginary part of the dielectric constant descend, but their original electrical properties cannot completely restored. After chemical moisture absorption appears inside the material, the residual space charges increase significantly and the charge dissipation rate slow down obviously.

• KSBB Journal
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• v.30 no.4
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• pp.166-174
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• 2015

In this study, an efficient whole cell-based biotransformation for the production of liquiritigenin was developed using Laetiporus sulphureus CS0218 as biocatalyst and aqueous extracts of Glycyrrhiza uralensis as co-substrate, respectively. In order to determine the efficacy of this method, the optimal bioconversion conditions including mycelial growth, three important enzyme activities (${\beta}$-glucosidase, ${\alpha}$-rhamnosidase and ${\beta}$-xylosidase), and apparent viscosity of culture broth were monitored. After optimization, aqueous extracts of G. uralensis were added to the culture medium to directly produce algycone liquiritigenin. By applying this strategy, 67.5% of liquiritin was converted to liquiritigenin at pH 3.0 after 9 days of incubation and finally liquiritigenin was purified from the reaction mixture. And then, their biological activities including anti-oxidant and superoxide dismutase were observed. In fact, purified liquiritigenin was capable of bi-directional functions (i.e., either up-regulation or down-regulation of SIRT1 which is associated with aging). The results indicate that this strategy would be beneficial to produce biologically active liquiritigenin and could be used in pharmaceutical, cosmetic and food applications.

• Transactions of Materials Processing
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• v.30 no.2
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• pp.61-68
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• 2021

As part of efforts to reduce the weight of automotive body-in-white, a hybrid center pillar with high strength 7075 aluminum alloy (AA7075) sheet and carbon fiber reinforced plastic (CFRP) has been recently studied. In the fabrication of the AA7075-CFRP hybrid center pillar, the AA7075 sheet might go through heating-forming-in-die quenching (HFQ), artificial aging, hybridizing, and then paint baking processes. In this study, we investigate the effects of the heat treatment history associated with each process on the tensile strength of the AA7075 sheet. Typical heat treatment conditions are HFQ for 20 minutes at 480℃ and then cooling down with die, artificial aging of T6 temper for 24 hours at 120℃, hybridizing for 10 minutes at 150℃, and paint baking for 20 minutes at 180℃. The tensile strength of the AA7075 sheet is continuously increased by a series of heat treatments of hybridizing and paint baking and is expected to have yield stress above 500MPa without artificial aging of T6 temper.

• BMB Reports
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• v.48 no.11
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• pp.595-596
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• 2015

Skeletal muscle exhibits a loss of muscle mass and function with age. Decreased regenerative potential of muscle stem/progenitor cells is a major underlying cause of sarcopenia. We analyzed microRNAs (miRNA) that are differentially expressed in young and old myoblasts, to identify novel intrinsic factors that play a degenerative role in aged skeletal muscle. miR-431, one of decreasing miRNAs in old myoblasts, improved the myogenic differentiation when overexpressed in old myoblast, but suppressed their myogenic capability in knockdowned young myoblasts. We found that miR-431 directly binds to 3` untranslated regions (UTR) of Smad4 mRNA, and decreases its expression. Given that SMAD4 is one of the downstream effectors of TGF-β, a well-known degenerative signaling pathway in myogenesis, the decreased miR-431 in old myoblast causes SMAD4 elevation, thus resulting in defective myogenesis. Exogenous expression of miR-431 greatly improved the muscle regeneration in the cardiotoxin-injured hindlimb muscle of old mice by reducing SMAD4 levels. Since the miR-431 seed sequence is conserved in human SMAD4 3'UTR, miR-431 regulates the myogenic capacity of human skeletal myoblasts in the same manner. Our results suggest that age-associated miR-431 is required for the maintenance of the myogenic capability in myoblasts, thus underscoring its potential as a therapeutic target to slow down muscle aging.