• Journal of Surface Science and Engineering
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• v.45 no.2
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• pp.53-60
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• 2012

Modulated Pulse Power (MPP) magnetron sputtering is a new high-power pulsed magnetron sputtering (HPPMS) technology which overcomes the low deposition rate problem by modulating the pulse voltage shape, amplitude, and the duration. Highly ionized magnetron sputtering can be performed without arcing because it can be controlled as multiple steps of micro pulses within one overall pulse period in the range of 500-3,000 ${\mu}s$. In this study, the various waveforms of discharge voltage and current for micro pulse sets of MPP were investigated to find the possibility of controlling the strongly ionized plasma mode. Enhanced ionization of the sputtered metal atoms was obtained by OES. Large grained columnar structure can be grown by the strongly ionized plasma mode in the AZO deposition using MPP. In the most highly ionized deposition condition, the preferred orientation of (002) plane decreased, and the resistivity, therefore, increased by the plasma damage.

• Toxicological Research
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• v.27 no.4
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• pp.261-267
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• 2011

Artemisia iwayomogi, a member of the Compositae, is a perennial herb easily found in Korea and used as a traditional medicine to treat liver disease. AIP1, a water-soluble carbohydrate fraction from Artemisia iwayomogi, showed anti-tumor and immuno-modulating activities in animal studies. A subacute toxicological evaluation of AIP1 was performed for 4 weeks in ICR mice. After administration of AIP1 (0, 20, 100, 500 mg/kg/day), the clinical signs, mortalities, body weight changes, hematology, blood clinical biochemistry, urinalysis, organ histopathology, organ weights and gross finding were examined. The results showed that there were no significant differences in body weight changes, food intakes, water consumptions, or organ weights among different dose groups. Also we observed no death and abnormal clinical signs during the experimental period. Between the groups orally treated with AIP1 and the control group, there was no statistical significance in hematological test or serum biochemical values. Histopathological examination showed no abnormal changes in AIP1 groups. These results suggest that no observed adverse effect level (NOAEL) of the oral administration of AIP1 for 4 weeks was considered to be more than 500 mg/kg/day in mice under the condition investigated in current study.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05a
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• pp.471-476
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• 1996

In this study, the method to use the phase shift keying (PSK) communication technique in smart transmitter is presented. In nuclear applications. smart transmitters for various parameters are expected to improve the accuracy of measurement and to reduce the load of calibration work. The capability of communication in field level is the most important merit of the smart transmitter. The most popular method is using of digital and analog techniques simultaneously - transmitting measurements from the field at 4∼20mA while modulating the current to carry digital information in both directions over the same twisted pairs. Conventional smart transmitters use the frequency shift keying (FSK) method for digital communication. Generally, however, the FSK method has the speed limit at 1200 bps. Amount of information to transmit becomes increasing as the processing technique is improved. The PSK method is noticeable alternative for high speed digital communication, but it has non-zero DC component. In order to use the PSK method in the field transmission with smart transmitter, the method to remove the DC component is studied in this work.

• Journal of Power Electronics
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• v.19 no.4
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• pp.968-979
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• 2019

Recently, there has been increased interest in the study of multiphase machines due to their higher fault-tolerant capability when compared to their conventional three-phase counterparts. For six-phase machines, stator windings configured with a single isolated neutral (1N) provide significantly more post-fault torque/power than two isolated neutrals (2N). Hence, this configuration is preferred in applications where post-fault performance is critical. It is well known that min-max injection has been commonly used for three-phase and multiphase machines in healthy condition to maximize the modulation limit. However, there is a lack of discussion on min-max injection for post-fault condition. Furthermore, the effects in terms of the common-mode voltage (CMV) in modulating signals has not been discussed. This paper investigates the effect of min-max injection in post fault-tolerant control on the voltage and speed limit of a symmetrical six-phase induction machine with single isolated neutral. It is shown that the min-max injection can minimize the amplitude of reference voltage, which maximizes the modulation index and post-fault speed of the machine. This in turn results in a higher post-fault power.

• BMB Reports
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• v.51 no.12
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• pp.613-622
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• 2018

RNA helicases DDX5 and DDX17 are multitasking proteins that regulate gene expression in different biological contexts through diverse activities. Special attention has long been paid to their function as coregulators of transcription factors, providing insight about their functional association with a number of chromatin modifiers and remodelers. However, to date, the variety of described mechanisms has made it difficult to understand precisely how these proteins work at the molecular level, and the contribution of their ATPase domain to these mechanisms remains unclear as well. In light of their association with long noncoding RNAs that are key epigenetic regulators, an emerging view is that DDX5 and DDX17 may act through modulating the activity of various ribonucleoprotein complexes that could ensure their targeting to specific chromatin loci. This review will comprehensively describe the current knowledge on these different mechanisms. We will also discuss the potential roles of DDX5 and DDX17 on the 3D chromatin organization and how these could impact gene expression at the transcriptional and post-transcriptional levels.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.37 no.1
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• pp.1-10
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• 2024

Direct use of sunlight through the glass windows is an efficient way to reduce the energy consumption related to the heating, cooling, and lighting. Introduction of near-infrared modulating properties through colloidal doped metal oxide nanocrystals into the classical electrochromic materials accelerates the development of next-generation electrochromic devices. There has been a steady enhancement in the performance of electrochromic devices, necessitating a review of the recent progress in next-generation electrochromic devices employing doped metal oxide nanocrystals. This review provides an overview of the current developments in next-generation electrochromic smart windows utilizing colloidal doped metal oxide nanocrystals, with a focus on the key factors for achieving these advanced windows. Colloidal doped metal oxide nanocrystals are a crucial component in realizing and bringing to market the next generation of electrochromic windows, though further research and development are still required in this regard.

• The Korean Journal of Pain
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• v.34 no.2
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• pp.176-184
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• 2021

Background: Diabetes-related neuropathic pain frequently occurs, and the underpinning mechanism remains elusive. The periaqueductal gray (PAG) exhibits descending inhibitory effects on central pain transmission. The current work aimed to examine whether inflammatory cytokines regulate mechanical allodynia and thermal hyperalgesia induced by diabetes through the phosphoinositide 3-kinase (PI3K)-mammalian target of rapamycin (mTOR) pathway in the PAG. Methods: Streptozotocin (STZ) was administered intraperitoneally to mimic allodynia and hyperalgesia evoked by diabetes in rats. Behavioral assays were carried out for determining mechanical pain and thermal hypersensitivity. Immunoblot and ELISA were performed to examine PAG protein amounts of interleukin-1β (IL-1β), IL-6, and tumor necrosis factor-α (TNF-α), as well as their corresponding receptors in STZ rats, and the expression of PI3K/protein kinase B (Akt)/mTOR signaling effectors. Results: Increased PAG p-PI3K/p-Akt/p-mTOR protein amounts were observed in STZ-induced animals, a PI3K-mTOR pathway inhibition in the PAG attenuated neuropathic pain responses. Moreover, the PAG concentrations of IL-1β, IL-6, and TNF-α and their receptors (namely, IL-1R, IL-6R, and tumor necrosis factor receptor [TNFR] subtype TNFR1, respectively) were increased in the STZ rats. Additionally, inhibiting IL-1R, IL-6R, and TNFR1 ameliorated mechanical allodynia and thermal hyperalgesia in STZ rats, alongside the downregulation of PI3K-mTOR signaling. Conclusions: Overall, the current study suggests that upregulated proinflammatory cytokines and their receptors in the PAG activate PI3K-mTOR signaling, thereby producing a de-inhibition effect on descending pathways in modulating pain transmission, and eventually contributing to neuropathic pain.

• Sleep Medicine and Psychophysiology
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• v.28 no.2
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• pp.53-69
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• 2021

Sleep disorders, increasingly prevalent in the general population, induce impairment in daytime functioning and other clinical problems. As changes in cortical excitability have been reported as potential pathophysiological mechanisms underlying sleep disorders, multiple studies have explored clinical effects of modulating cortical excitability through non-invasive brain stimulation in treating sleep disorders. In this study, we critically reviewed clinical studies using non-invasive brain stimulation, particularly transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS), for treatment of sleep disorders. Previous studies have reported inconsistent therapeutic effects of TMS and tDCS for various kinds of sleep disorders. Specifically, low-frequency repetitive TMS (rTMS) and cathodal tDCS, both of which exert an inhibitory effect on cortical excitability, have shown inconsistent therapeutic effects for insomnia. On the other hand, high-frequency rTMS and anodal tDCS, both of which facilitate cortical excitability, have improved the symptoms of hypersomnia. In studies of restless legs syndrome, high-frequency rTMS and anodal tDCS induced inconsistent therapeutic effects. Single TMS and rTMS have shown differential therapeutic effects for obstructive sleep apnea. These inconsistent findings indicate that the distinctive characteristics of each non-invasive brain stimulation method and specific pathophysiological mechanisms underlying particular sleep disorders should be considered in an integrated manner for treatment of various sleep disorders. Future studies are needed to provide optimized TMS and tDCS protocols for each sleep disorder, considering distinctive effects of non-invasive brain stimulation and pathophysiology of each sleep disorder.

• Korean Chemical Engineering Research
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• v.62 no.2
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• pp.133-141
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• 2024

Atherosclerosis, a disease with high morbidity and mortality worldwide, is a chronic inflammatory disease that is a major cause of cardiovascular diseases such as stroke and myocardial infarction. Atherosclerosis is characterized by the accumulation of lipid deposits in the arteries, forming atheromas. This leads to the narrowing of the arteries and thrombosis. Recently, the need to develop bio-derived anti-atherosclerotic materials has been highlighted with concerns about the side effects of synthetic therapeutics. Accordingly, related research (such as the discovery of biomaterials for the improvement and treatment of atherosclerosis and the identification of mechanisms) has been actively conducted. Biomaterials including polysaccharides, polyphenols, and coenzyme Q10 have been reported to inhibit or delay symptoms by modulating factors involved in the development of atherosclerosis. For biomaterials with superior activity, in vivo anti-atherosclerotic activity has been confirmed. In this review, the pathogenesis of atherosclerosis was investigated, and the current status and application prospects of biomaterials with anti-atherosclerotic activity were proposed.

• Molecules and Cells
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• v.39 no.5
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• pp.418-425
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• 2016

Resveratrol (RES) plays a critical role in the fate of cells and longevity of animals via activation of the sirtuins1 (SIRT1) gene. In the present study, we intend to investigate whether RES could promote the self-renewal and neural-lineage differentiation in human umbilical cord derived MSCs (hUC-MSCs) in vitro at concentrations ranging from 0.1 to $10{\mu}M$, and whether it exerts the effects by modulating the SIRT1 signaling. Herein, we demonstrated that RES at the concentrations of 0.1, 1 and $2.5{\mu}M$ could promote cell viability and proliferation, mitigate senescence and induce expression of SIRT1 and Proliferating Cell Nuclear Antigen (PCNA) while inhibit the expression of p53 and p16. However, the effects were reversed by 5 and $10{\mu}M$ of RES. Furthermore, RES could promote neural differentiation in a dose-dependent manner as evidenced by morphological changes and expression of neural markers (Nestin, ${\beta}III-tubulin$ and NSE), as well as pro-neural transcription factors Neurogenin (Ngn)1, Ngn2 and Mash1. Taken together, RES exerts a dosage-dependent effect on the self-renewal and neural differentiation of hUC-MSCs via SIRT1 signaling. The current study provides a new strategy to regulate the fate of hUC-MSCs and suggests a more favorable in vitro cell culture conditions for hUCMSCs-based therapies for some intractable neurological disorders.