• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2000.11a
• /
• pp.162-165
• /
• 2000

To investigate the effect of metal electrode in electroluminescent[EL] devices, we fabricated EL devices of ITO/P3HT/Al, ITO/P3HT/LiF/Al and ITO/P3HT/Mg:In structure. In current-voltage-light power characteristics, turn-on voltage of EL devices using LiF insulating layer and Mg:In(2.8V) metal electrode is lower than EL device using Al(4.2V). Besides the external quantum efficiency is improved also. The reason is related to carrier mobility and carrier injection, which would affect the hole-electron balance. In the device with Al electrode, holes injected from indium-tin-oxide[ITO] to poly(3-hexylthiophene)[P3HT] might reach the Al electrode without interacting with injected electrons, because the electron injection efficiency was very low for this electrode. Besides oxidation of the Al electrode is likely due to holes reaching the cathode without meeting injected electrons. Another possible reason for the higher EL efficiency may be the insulating layer playing the role of a tunneling barrier for holes to the Al electrode. In all EL devices, the orange-red light was clearly visible in a dark room. Maximum peak wavelength of EL spectrum emitted at 640nm in accordance with photon energy 1.9eV

• Proceedings of the Korean Vacuum Society Conference
• /
• 2000.02a
• /
• pp.25-25
• /
• 2000

In this talk we discuss the dynamics of hydrogen on the Si(100)-2xl surface. At room temperature the sticking coefficient for molecular hydrogen on this surface is less than 10sup-12. However, hydrogen molecules desorbing from the surface do not have an excess of energy, suggesting at best a small barrier on the exit channel. These observations have led to speculation about the validity of detailed balance in this system. Here we show that this discrepancy can be explained by considering both the surface-molecule co-ordinate and that associated with the Si-Si dimer bond tiltangle. By preparing the surface dimers with a specific tiltangle we demonstrate that the barrier to adsorption is a function of this angle and that the sticking coefficient dramatically increase for certain angles. The adsorption-desopption dynamics can then be described in terms of a common potential energy hypersurface involving both of these co-ordinates. The implications of these observations are also discussed. The dynamics of adsorbed hydrogen atoms on the Si(100) surface is also described. Paired dangling bonds produced following recombinative hydrogen desorption are mobile at elevated temperatures. Pairs of dangling bonds are observed to dissociate, diffuse, and ultimately recombine. At sufficiently elevated temperatures dangling bond exchange reactions are observed. These data are analyzed in terms of an attractive zone and an effective binding interaction between dangling bonds. Insights that this provides into the nature of surface defects and the localized chemistry that occurs on this surface, are also discussed.

• Journal of Ginseng Research
• /
• v.45 no.5
• /
• pp.599-609
• /
• 2021

Ginseng has long been considered as an herbal medicine. Recent data suggest that ginseng has antiinflammatory properties and can improve learning- and memory-related function in the central nervous system (CNS) following the development of CNS neuroinflammatory diseases such as Alzheimer's disease, cerebral ischemia, and other neurological disorders. In this review, we discuss the role of ginseng in the neurovascular unit, which is composed of endothelial cells surrounded by astrocytes, pericytes, microglia, neural stem cells, oligodendrocytes, and neurons, especially their blood-brain barrier maintenance, anti-inflammatory effects and regenerative functions. In addition, cell-cell communication enhanced by ginseng may be attributed to regeneration via induction of neurogenesis and angiogenesis in CNS diseases. Thus, ginseng may have therapeutic potential to exert cognitive improvement in neuroinflammatory diseases such as stroke, traumatic brain injury, multiple sclerosis, Parkinson's disease, and Alzheimer's disease.

• Journal of Environmental Science International
• /
• v.30 no.5
• /
• pp.399-406
• /
• 2021

The dissolution of ionized gas in dielectric barrier plasma, similar to the principle of ozone generation, is a major performance-affecting factor. In this study, the plasma gas dissolving performance of a gas mixing-circulation plasma process was evaluated using an experimental design methodology. The plasma reaction is a function of four parameters [electric current (X₁), gas flow rate (X₂), liquid flow rate (X₃) and reaction time (X₄)] modeled by the Box-Behnken design. RNO (N, N-Dimethyl-4-nitrosoaniline), an indictor of OH radical formation, was evaluated using a quadratic response surface model. The model prediction equation derived for RNO degradation was shown as a second-order polynomial. By pooling the terms with poor explanatory power as error terms and performing ANOVA, results showed high significance, with an adjusted R² value of 0.9386; this indicate that the model adequately satisfies the polynomial fit. For the RNO degradation, the measured value and the predicted values by the model equation agreed relatively well. The optimum current, gas flow rate, liquid flow rate and reaction time were obtained for the highest desirability for RNO degradation at 0.21 A, 2.65 L/min, 0.75 L/min and 6.5 min, respectively.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.21 no.1
• /
• pp.41-48
• /
• 2022

Vehicle vibration was introduced in the time and frequency domains using fast Fourier transform (FFT) analysis. In particular, a vibration mode analysis and characteristics of the frequency response function (FRF) in a sport utility vehicle (SUV) passing over a bump barrier at different speeds was performed systematically. The response behavior of the theoretical acceleration was obtained using a numerical method applied to the forced vibration model. The amplitude and frequency of the external force on the vehicle cause various power spectra with individual intrinsic system frequencies. In this regard, several modes of power spectra were acquired from the spectra and are discussed in this paper. The proposed technique can be used for monitoring the acceleration in a vehicle passing over a bump barrier. To acquire acceleration signals, various experimental runs were performed using the SUV. These acceleration signals were then used to acquire the FRF and to conduct mode analysis. The vehicle characteristics according to the vehicle condition were analyzed using FRF. In addition, the vehicle structural system and bump passing frequencies were discriminated based on their power spectra and other FRF spectra.

• Food Science of Animal Resources
• /
• v.42 no.6
• /
• pp.1046-1060
• /
• 2022

This study aimed to investigate the effects of the metabolites of Latilactobacillus curvatus BYB3 and indole-activated aryl hydrocarbon receptor (AhR) to increase the tight junction (TJ) proteins in an in vitro model of intestinal inflammation. In a Western blot assay, the metabolites of L. curvatus BYB3 reduced the TJ demage in lipoploysaccharide (LPS) stimulated-Caco-2 cells. This reduction was a result of upregulating the expression of TJ-associated proteins and suppressing the nuclear factor-κB signaling. Immunofluorescence images consistently revealed that LPS disrupted and reduced the expression of TJ proteins, while the metabolites of L. curvatus BYB3 and indole reversed these alterations. The protective effects of L. curvatus BYB3 were observed on the intestinal barrier function when measuring transepithelial electrical resistance. Using high-performance liquid chromatography analysis the metabolites, the indole-3-latic acid and indole-3-acetamide concentrations were found to be 1.73±0.27 mg/L and 0.51±0.39 mg/L, respectively. These findings indicate that the metabolites of L. curvatus BYB3 have increasing mRNA expressions of cytochrome P450 1A1 (CYP1A1) and AhR, and may thus be applicable for therapy of various inflammatory gut diseases as postbiotics.

• Journal of the Society of Cosmetic Scientists of Korea
• /
• v.49 no.1
• /
• pp.87-96
• /
• 2023

This study was conducted to discover substances that regulate skin surface acidification using human epidermal keratinocyte cell lines, and to investigate their effects on the moisturizing ability and skin barrier function of the stratum corneum. Prunella vulgaris (P. vulgaris) is an herb widely distributed in Northwest Africa and North America that has been studied for its anti-apoptotic, antioxidant, and anti-inflammatory effects. However, research on the regulation of NHE1 expression and the restoration of skin barrier function has not been conducted. Analysis of P. vulgaris revealed the presence of rosmarinic acid and caffeic acid as active ingredients, which were tested for toxicity in human epidermal keratinocyte cell lines (HaCaT), and showed no toxic effects were observed at high concentarion (100 ㎍/mL or 100 µM). It is known that sodium-hydrogen ion exchange pumps (NHE1) decrease in expression in aging skin to maintain the acidic pH of the stratum corneum, and it is hypothesized that this decrease plays an important role in the impaired restoration of skin barrier function in aging skin. P. vulgaris extract and caffeic acid increased the expression of NHE1 in keratinocytes, increased the expression of natural moisturizing factor (NMF) precursor filaggrin and ceramide synthesis enzyme serine palmitoyl transferase (SPT). In addition, P. vulgaris and caffeic acid decreased the extracellular pH of keratinocytes, indicating a direct effect on skin pH regulation. Taken together, these results suggest that P. vulgaris and caffeic acid can regulate skin pH through NHE1 modulation, and may help to restore skin barrier function by increasing NMF and ceramide synthesis. These results show the possibility that honeysuckle and caffeic acid can have a positive effect on skin health, and can be the basis for the development of new skin protection products using them.

• Journal of the Society of Cosmetic Scientists of Korea
• /
• v.47 no.1
• /
• pp.49-56
• /
• 2021

In this study, a liquid crystal emulsion with a composition ratio similar to the skin lipid composition was manufactured using ceramide, glycolipids, cholesterol, and fatty acids, and a polarized microscope was used to identify liquid crystal particles in the formulation, and a cryso-SEM was used to confirm the formation of a multilayer structure. The above samples were stored at room temperature for one month and the liquid crystal structure was continuously maintained through microscopic observation. In addition, a cream composition containing liquid crystal emulsion was manufactured, and the efficiency of ceramide skin penetration was confirmed using three-dimensional artificial skin. Clinical trials were conducted using the cream composition and the results of clinical trials on skin barrier improvement were confirmed by measuring skin moisture retention (skin hydration) and transepidermal water loss (T EWL) of subjects compared to general emulsion.

• Childhood Kidney Diseases
• /
• v.19 no.2
• /
• pp.65-70
• /
• 2015

It is well known that proteins present in the primary urine are reabsorbed in the renal proximal tubules, and that this reabsorption is mediated via the megalin-cubilin complex and the neonatal $Fc{\gamma}$ receptor. However, the reabsorption is also thought to be influenced by an electrostatic interaction between protein molecules and the microvilli of the renal proximal tubules. By analyzing the charge diversity of urinary IgG, we showed that this reabsorption process occurs in a cationic charge-preferential manner. The charge-selective molecular sieving function of the glomerular capillary walls has long been a target of research since Brenner et al. demonstrated the existence of this function by a differential clearance study by using the anionic dextran sulfate polymer. However, conclusive evidence was not obtained when the study was performed using differential clearance of serum proteins. We noted that immunoglobulin (Ig) A and IgG have similar molecular sizes but distinct molecular isoelectric points. Therefore, we studied the differential clearance of these serum proteins (clearance IgA/clearance IgG) in podocyte diseases and glomerulonephritis. In addition, we studied this differential clearance in patients with Dent disease rather than in normal subjects because the glomerular sieving function is considered to be normal in subjects with Dent disease. Our results clearly showed that the charge-selective barrier is operational in Dent disease, impaired in podocyte disease, and lacking in glomerulonephritis.

• International Journal of Aeronautical and Space Sciences
• /
• v.18 no.4
• /
• pp.719-728
• /
• 2017

This paper proposes a synthesis of new guidance law to generate an evasive maneuver against enemy's missile interception while considering its impact angle, acceleration, and field-of-view constraints. The first component of the synthesis is a new function of repulsive Artificial Potential Field to generate the evasive maneuver as a real-time dynamic obstacle avoidance. The terminal impact angle and terminal acceleration constraints compliance are based on Time-to-Go Polynomial Guidance as the second component. The last component is the Logarithmic Barrier Function to satisfy the field-of-view limitation constraint by compensating the excessive total acceleration command. These three components are synthesized into a new guidance law, which involves three design parameter gains. Parameter study and numerical simulations are delivered to demonstrate the performance of the proposed repulsive function and guidance law. Finally, the guidance law simulations effectively achieve the zero terminal miss distance, while satisfying an evasive maneuver against intercept missile, considering impact angle, acceleration, and field-of-view limitation constraints simultaneously.