• Transactions of the Korean Society of Automotive Engineers
• /
• v.24 no.5
• /
• pp.605-611
• /
• 2016

Mg alloy sheet exhibits significant differences in tensile and compressive yield stress depending on the temperature, as well as variations in its hardening behavior. Such unusual behavior makes it difficult to simulate the forming process of Mg alloy sheets. Results of analysis tend to deviate significantly from the experimental data because commercial software do not completely implement the unusual hardening behavior, yield asymmetry and temperature dependent changes in the Mg alloy's material properties. In the previous study, an in-plane tension-compression cyclic tester was developed to predict the cyclic behavior of Mg alloy sheets at an elevated temperature of up to $250^{\circ}C$. A new constitutive equation was suggested to analyze the unusual behavior, and was implemented in the commercial software in the form of user subroutine. In this paper, a stamping process of Mg seat cushion panel for automotive parts was simulated using the experimental data and user subroutine. Based on the analysis, an optimal temperature condition was determined and a stamping die shape at each step was suggested in the non-isothermal stamping of Mg alloy sheets.

• Journal of Korean Society on Water Environment
• /
• v.32 no.2
• /
• pp.135-141
• /
• 2016

This study investigated changes of hydrology, soil characteristics, riparian vegetation communities, and geomorphology in sandbars before and after sand-mining to determine the effect of sand-mining at upstream of Guemgang and Bochungcheon streams in Korea. Sand-mining events affected the mining area. They supplied organic matters and nutrients during flood. Sediment deposition caused soil texture change and expansion of vegetation area. However, riverbeds were stabilized after the disturbance. According to the analyses of aerial photographs, the vegetation area was significantly expanded in both dam-regulated streams and dam-unregulated streams after sand-mining. Willow shrubs advanced in disturbed area at an average of 10 years after sand-mining. It took willows trees 10.6 years to become dominant communities. Therefore, it took a total of 20.6 years for new riparian forest to form in sandbar after sand-mining. Our results confirmed that stream flow condition were dependent on vegetation recruitment in dam-regulated streams and dam-unregulated streams. For willow recruitment in unregulated streams, calculation of water level below dimensionless bed shear stress is important because low water level variation is a limiting factor of vegetation recruitment.

• Korean Journal of Medicinal Crop Science
• /
• v.25 no.6
• /
• pp.404-410
• /
• 2017

Background: Hair loss related syndromes are increasing due to environmental pollution and stress. Hair care products are mainly prepared by mixing chemicals and natural extracts, such as those obtained from medicinal plants. The purpose of this study was to investigate the effects of 70% ethanol extracts from the flowers of Calendula officinalis, fruit body of Phellinus linteus, and the whole plant of Houttuynia cordata on the growth of CCD-986 cells, hair follicle dermal papilla cells (HFDPC), and 3T3-L1 cells. Methods and Results: All sample extracts at all concentrations, except for that from P. linteus fruit body at $500{\mu}g/m{\ell}$, were cytotoxic to CCD-986 cells. However, none of the sample extracts were cytotoxic to HFDPC. The lipid differentiation of 3T3-L1 cells regulates hair regeneration via secretion of platelet derived growth factor. The 70% ethanol extract of H. cordata whole plant promoted hair growth. Adipogenesis rate significantly increased in a treatment concentration-dependent manner. Conclusions: These results suggest that 70% ethanol extracts of C. officinalis flower, P. linteus fruit body and H. cordata could be used for the development of hair care products.

• Korean Journal of Pharmacognosy
• /
• v.34 no.3 s.134
• /
• pp.242-245
• /
• 2003

The effects of chelidonine, a benzophenanthridine isoquinoline alkaloid, on L-DOPA-induced cytotoxicity in PC12 cells were investigated. The treatment of PC12 cells with chelidonine $(1-4\;{\mu}M)$ decreased dopamine content in a dose-dependent manner (30.2% inhibition at $4\;{\mu}M)$. Chelidonine was not cytotoxic up to $4\;{\mu}M)$. However, chelidonine at concentrations higher than $5\;{\mu}M$ caused a cytotoxicity in PC12 cells. L-DOPA at concentrations higher than $50\;{\mu}M$ led to cell damage by oxidative stress in PC12 cells. Chelidonine at non-cytotoxic concentration ranges of $1-4{\mu}M$ aggravated L- DOPA $(20-50\;{\mu}M)$-induced cytotoxicity in PC12 cells. The L-DOPA-induced cytotocxicity was synergistically stimulated by chelidonine at concentrations grader than $5\;{\mu}M$. These data demonstrate that chelidonine exacerbates L-DOPA-induced cytotoxicity. Therefore, it is proposed that the long-term L-DOPA therapeutic patients with chelidonine may need to be checked for the adverse symptoms.

• Journal of Physiology & Pathology in Korean Medicine
• /
• v.26 no.1
• /
• pp.59-66
• /
• 2012

Oxidative stress has been implicated in cutaneous damage in various inflammatory skin diseases, including atopic dermatitis. The present study was undertaken to investigate the antioxidative and anti-inflammatory activities of the extract of Duchesnea chrysantha (DCE). DEC was prepared by extracting with 80% ethanol. Total flavonoids and polyphenols were measured by a colorimetric assay. The free radical scavenging activity of the extract was analyzed by the DPPH (1,1-diphenyl-2-picryl hydrazyl), ABTS (2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) and Griess reagent assay. An oxidative product of nitric oxide (NO), was measured in the culture medium by the Griess reaction. The level of prostaglandin $E_2$ ($PGE_2$) was measured by enzyme-linked immunosorbent assay. The expressions of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) were measured by Western blot analysis. Total flavonoid and polyphenol contents of DCE were included $24.73{\pm}0.45$ and $178.77{\pm}2.65$, respectively. DCE significantly increased electron donating ability (DPPH), nitrite scavenging (NO) and ABTS reducing activity in dose dependant. We investigated the anti-inflammatory effects of DCE on lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. DCE significantly suppressed NO and prdstaglandin $E_2$ ($PGE_2$) in dose dependant. Furthermore, the levels of iNOS and COX-2 protein expressions were markedly suppressed by the treatment with DCE in a dose dependent manner. These results suggest that DEC may has value as natural product with its high quality functional components, antioxidative and anti-inflammatory activities.

• Journal of Physiology & Pathology in Korean Medicine
• /
• v.21 no.3
• /
• pp.626-633
• /
• 2007

To access the safety and efficacy of Chungyeoldodam-tang(CDT), a traditional herbal medicine prescription, on hypertension we examined various parameters involved in the pathogenesis of hypertension. CDT seems to be safe because CDT at the concentrations lower that 250 ug/ml showed no toxic effects in cultured human fibroblast and no toxic effects on liver function. The production of reactive oxygen species (ROS) were greatly decreased in CDT treated group compared with control, and angiotensin converting enzyme activities were reduced by CDT in a dose dependent manner. There was no differences in weight of hearts between control and CDT treated group. The blood pressure and pulse rate were significantly decreased. CDT greatly reduced the levels of plasma hormones including aldosterone, dopamine, and norepinephrine, but not epinephrine, and serum electrocytes including Na$^+$ and Cl$^-$, but not K$^+$. were also decreased. The levels of uric acid, BUN and creatinine were significantly decreased compared with control. These results suggested that CDT has suppressive effects on various pathologic factors in hypertension, and CDT has potential as a safe and effective therapeutics for hypertension.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2010.08a
• /
• pp.233-233
• /
• 2010

CdS thin films were deposited on glass substrates by R.F. magnetron sputtering method and some of the samples were treated by rapid thermal annealing (RTA) process. Effects of thermal annealing on structural and optical properties were investigated at different temperatures ranging from 100 to $600^{\circ}C$. The crystallographic structure of the films and the size of the crystallites in the films were studied by X-ray diffraction. The crystallite sizes were found to increase, and the X-ray diffraction patterns were seen to sharpen by annealing. Optical properties of the films were calculated using the envelope method and the photoluminescence measurements. The optical properties of the films were seen to be dependent on the film thicknesses. The energy gap of the films was found to decrease by annealing. The band edge sharpness of the optical absorption was seen to oscillate by thermal annealing. Annealing over $400^{\circ}C$ was seen to degrade the optical properties of the film. The best annealing temperature for the films was found to be $400^{\circ}C$ from the optical properties. It is observed that the CdS film annealed at $400^{\circ}C$ reveals the strongest UV emission intensity and narrowest full width at half maximum among the temperature ranges studied. The enhanced UV emission from the film annealed at $400^{\circ}C$ is attributed to the improved crystalline quality of CdS thin film due to the effective relaxation of residual compressive stress and achieving maximum grain size. The results show that heat treatments under optimal annealing condition can provide significant improvements in the properties of CdS thin films.

• Journal of Ginseng Research
• /
• v.37 no.4
• /
• pp.379-388
• /
• 2013

Diabetic nephropathy is one of the serious complications in patients with either type 1 or 2 diabetes mellitus but current treatments remain unsatisfactory. Results of clinical research studies demonstrate that Panax ginseng can help adjust blood pressure and reduce blood sugar and may be advantageous in the treatment of tuberculosis and kidney damage in people with diabetes. The heat-processing method to strengthen the efficacy of P. ginseng has been well-defined based on a long history of ethnopharmacological evidence. The protective effects of P. ginseng on pathological conditions and renal damage associated with diabetic nephropathy in the animal models were markedly improved by heat-processing. The concentrations of less-polar ginsenosides (20(S)-Rg3, 20(R)-Rg3, Rg5, and Rk1) and maltol in P. ginseng were significantly increased in a heat-processing temperature-dependent manner. Based on researches in animal models of diabetes, ginsenoside 20(S)-Rg3 and maltol were evaluated to have therapeutic potential against diabetic renal damage. These effects were achieved through the inhibition of inflammatory pathway activated by oxidative stress and advanced glycation endproducts. These findings indicate that ginsenoside 20(S)-Rg3 and maltol are important bioactive constituents of heat-processed ginseng in the control of pathological conditions associated with diabetic nephropathy.

• Journal of the Society of Naval Architects of Korea
• /
• v.53 no.2
• /
• pp.85-91
• /
• 2016

The most important factor in the structural design of ships and offshore structures operating in arctic region is ice load, which results from ice-structure interaction during the ice collision process. The mechanical properties of ice related to strength and failure, however, show very complicated aspect varying with temperature, volume fraction of brine, grain size, strain rate and etc. So it is nearly impossible to establish a perfect material model of ice satisfying all the mechanical characteristics completely. Therefore, in general, ice collision analysis was carried out by relatively simple material models considering only specific aspects of mechanical characteristics of ice and it would be the most significant cause of inevitable errors in the analysis. Especially, it is well-known that the most distinctive mechanical property of ice is high dependency on strain rate. Ice shows brittle attribute in higher strain rate while it becomes ductile in lower strain rate range. In this study, the simulation method of ice collision to ship hull using the nonlinear dynamic FE analysis was dealt with. To consider the strain rate effects of ice during ice-structural interaction, strain rate dependent constitutive model in which yield stress and hardening behaviors vary with strain rate was adopted. To reduce the huge amount of computing time, the modeling range of ice and ship structure were restricted to the confined region of interest. Under the various scenario of ice-ship hull collision, the structural behavior of hull panels and failure modes of ice were examined by nonlinear FE analysis technique.

• The Korean Journal of Physiology and Pharmacology
• /
• v.25 no.4
• /
• pp.341-354
• /
• 2021

Cardamonin (CARD) is a chalconoid with anti-inflammatory and antioxidant properties, and it is present in several plants. We sought to explore whether CARD exerts any positive effects against hyperglycemia-induced testicular dysfunction caused by type 2 diabetes and aimed to identify its possible intracellular pathways. Adult male rats were subdivided into six groups: control, CARD, diabetic (DM), DM + glibenclamide (GLIB), DM + CARD and DM + GLIB + CARD. Type 2 DM induced a significant increase in blood glucose and insulin resistance, along with diminished serum insulin, testosterone and gonadotropins levels, which were associated with the impairment of key testicular androgenic enzymes and cellular redox balance. Administration of CARD at a dose of 80 mg/kg for 4 weeks effectively normalized all of these alterations, and the improvement was confirmed by epididymal sperm analysis. After treatment with CARD, the pathological changes in spermatogenic tubules were markedly improved. Significantly, CARD upregulated testicular glucose transporter-8 (GLUT-8) expression and had inhibitory effects on elevated autophagy markers and caspase-3 immunoreactive cells. Furthermore, our results revealed that CARD was able to attenuate damage via activation of Nrf2 through the p62-dependent degradation of testicular anti-Kelch-like ECH-associated protein-1 (Keap-1). In conclusion, this study suggests that CARD provides protection against diabetic stress-mediated testicular damage. The use of CARD with conventional anti-diabetic therapy was associated with improved efficacy compared with conventional therapy alone.