• Journal of Climate Change Research
• /
• v.7 no.3
• /
• pp.325-334
• /
• 2016

We projected the distribution of Hedera rhombea, an evergreen broad-leaved climbing plant, under current climate conditions and predicted its future distributions under global warming. Inaddition, weexplained model uncertainty by employing 9 single Species Distribution model (SDM)s to model the distribution of Hedera rhombea. 9 single SDMs were constructed with 736 presence/absence data and 3 temperature and 3 precipitation data. Uncertainty of each SDM was assessed with TSS (Ture Skill Statistics) and AUC (the Area under the curve) value of ROC (receiver operating characteristic) analyses. To reduce model uncertainty, we combined 9 single SDMs weighted by TSS and resulted in an ensemble forecast, a TSS weighted ensemble. We predicted future distributions of Hedera rhombea under future climate conditions for the period of 2050 (2040~2060), which were estimated with HadGEM2-AO. RF (Random Forest), GBM (Generalized Boosted Model) and TSS weighted ensemble model showed higher prediction accuracies (AUC > 0.95, TSS > 0.80) than other SDMs. Based on the projections of TSS weighted ensemble, potential habitats under current climate conditions showed a discrepancy with actual habitats, especially in the northern distribution limit. The observed northern boundary of Hedera rhombea is Ulsan in the eastern Korean Peninsula, but the projected limit was eastern coast of Gangwon province. Geomorphological conditions and the dispersal limitations mediated by birds, the lack of bird habitats at eastern coast of Gangwon Province, account for such discrepancy. In general, potential habitats of Hedera rhombea expanded under future climate conditions, but the extent of expansions depend on RCP scenarios. Potential Habitat of Hedera rhombea expanded into Jeolla-inland area under RCP 4.5, and into Chungnam and Wonsan under RCP 8.5. Our results would be fundamental information for understanding the potential effects of climate change on the distribution of Hedera rhombea.

• Biomolecules & Therapeutics
• /
• v.27 no.1
• /
• pp.85-91
• /
• 2019

Oxidative stress is considered a major contributor in the pathogenesis of diabetic neuropathy and in diabetes complications, such as nephropathy and cardiovascular diseases. Diabetic neuropathy, which is the most frequent complications of diabetes, affect sensory, motor, and autonomic nerves. This study aimed to investigate whether 7,8-dihydroxyflavone (7,8-DHF) protects SH-SY5Y neuronal cells against high glucose-induced toxicity. In the current study, we found that diabetic patients exhibited higher lipid peroxidation caused by oxidative stress than healthy subjects. 7,8-DHF exhibits superoxide anion and hydroxyl radical scavenging activities. High glucose-induced toxicity severely damaged SH-SY5Y neuronal cells, causing mitochondrial depolarization; however, 7,8-DHF recovered mitochondrial polarization. Furthermore, 7,8-DHF effectively modulated the expression of pro-apoptotic protein (Bax) and anti-apoptotic protein (Bcl-2) under high glucose, thus inhibiting the activation of caspase signaling pathways. These results indicate that 7,8-DHF has antioxidant effects and protects cells from apoptotic cell death induced by high glucose. Thus, 7,8-DHF may be developed into a promising candidate for the treatment of diabetic neuropathy.

• Journal of Veterinary Clinics
• /
• v.36 no.2
• /
• pp.102-105
• /
• 2019

Nitrotyrosine was found to be dependent on the severity of myxomatous mitral valve disease (MMVD). However, a correlation of serum nitrotyrosine concentration in dogs with MMVD and the progression of the disease has not been investigated. This study compared changes in serum nitrotyrosine concentration with the progression of MMVD. Nine client-owned dogs were recruited for the study. Dogs were classified by measuring the amount of regurgitation using echocardiography into mild, moderate, or severe MMVD groups. Serum nitrotyrosine concentration was measured by an enzyme-linked immunosorbent assay test. Serum nitrotyrosine concentration was significantly higher at 180 days than at 0 day (P < 0.05). However, serum nitrotyrosine concentration at 360 days was lower than that at 180 days (P < 0.05). Serum nitrotyrosine concentration at 540 days was lower than at 180 days (P < 0.05). There was no correlation between serum nitrotyrosine and left atrial to aortic root diameter ratio (LA/Ao ratio) (n = 33, $R^2=0.003$, P = 0.759). Also, there was no correlation between serum nitrotyrosine and vertebral heart score (VHS) (n = 33, $R^2=0.026$, P = 0.368) and left ventricular end-diastolic diameter, normalized for body weight by the formula (LVEDDN) (n = 33, $R^2=0.053$, P = 0.196). The results of the study suggest that the progression of MMVD is correlated with changes in serum nitrotyrosine concentration, which shows potential for use as a cardiac biomarker which can be used to analyze the progression of disease in MMVD.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2020.06a
• /
• pp.169-169
• /
• 2020

According to the IPCC analysis, severe climate changes are projected to occur in Korea as the temperature is expected to rise by 3.2 ℃, the precipitation by 15.6% and the sea level by 27cm by 2050. It is predicted that the occurrence of abnormal climate phenomena - especially those such as increase of concentrated precipitation and extreme heat in the summer season and severe drought in the winter season - that have happened in Korea in the past 30 years (1981-2010) will continuously be intensified and accelerated. As a result, the impact on and vulnerability of the water management sector is expected to be exacerbated. This research aims to predict the climate change impacts on streamflow of Daecheong Lake area of Geum River in South Korea during the summer and winter seasons, which show extreme meteorological events, and ultimately develop an integrated policy model in response. We projected and compared the streamflow changes of Daecheong Lake area of Geum River in South Korea in the near future period (2020-2040) and the far future period (2041-2060) with the reference period (1991-2010) using the HEC-HMS model. The data from a global climate model HadGEM2-AO, which is the fully-coupled atmosphere-ocean version of the Hadley Centre Global Environment Model 2, and RCP scenarios (RCP4.5 and RCP8.5) were used as inputs for the HEC-HMS model to identify the river basins where cases of extreme flooding or drought are likely to occur in the near and far future. The projections were made for the summer season (July-September) and the winter season(November-January) in order to reflect the summer monsoon and the dry winter. The results are anticipated to be used by policy makers for preparation of adaptation plans to secure water resources in the nation.

• Korean Journal of Weed Science
• /
• v.16 no.3
• /
• pp.210-220
• /
• 1996

Ten-day-old seedlings of the oxyfluorfen-tolerant and -susceptible rice cultivars with barnyardgrass, a typical susceptible weed were soaked in oxyfluorfen at $10^{-6}M$ for 2 hrs kept for 24 hrs in the dark, and exposed to light for 0, 2, 4, or 6 hrs to investigate changes in the activity and isozyme of antioxidative enzymes. The activities of antioxidative enzymes of APOX, CAL, POX, NR, GR, MDAR and SOD in the tolerant and susceptible rice cultivate themselves didn't show any difference but the activity in the susceptible barnyardgrass was very low in comparison with rice cultivars. The activity of lipoxygenase tended to be some slightly higher in the susceptible rice cultivars and barnyardgrass than in the tolerant rice cultivars. The activities of MDAR, POX, GR and SOD, antioxidative enzymes, were higher in the tolerant rice cultivars than in the susceptible rice cultivars and barnyardgrass after the treatment of oxyfluorfen. After the treatment of oxyfluorfen, in the change of POX isozyme, the activity of C band in the tolerant rice cultivars increased with increased concentration but it didn't in the susceptible rice cultivar. The activity of B band decreased slightly at $10^{-4}M$ in the susceptible barnyardgrass. Isozyme of GR, SOD and AO by the treatment of oxyfluorfen, the activity of each band between the tolerant and susceptible rice cultivars showed no difference but GR isozyme C band was disappeared in the susceptible barnyardgrass at $10^{-4}M$. In the change of esterase isozyme resulting from the treatment of oxyfluorfen, the activities of B, C and D bands decreased more in the susceptible rice cultivars than in tolerant rice cultivars, and A band was disappeared in the susceptible barnyardgrass at $10^{-4}M$.

• Asian-Australasian Journal of Animal Sciences
• /
• v.24 no.7
• /
• pp.993-1000
• /
• 2011

The aim of this study was to evaluate the potential of fermented red ginseng extract (FRGE) as feed additive in broilers and laying hens. In broilers, 480 Arbor Acre male broilers were randomly allotted to 4 treatments with 6 replications per treatment and 20 chicks per pen. The experiment lasted 5 weeks and dietary treatments were as follows: i) CON, basal diet; ii) FRGE1, basal diet+1 g/kg fermented red ginseng extract; iii) FRGE2, basal diet+2 g/kg fermented red ginseng extract and iv) FRGE3 basal diet+4 g/kg fermented red ginseng extract. Throughout the experiment, no effects were observed (p>0.05) in performance in response to FRGE. At the end of the experiment, FRGE administration improved (p<0.05) the lymphocyte level compared with CON. The relative weight of bursa of fabricius and spleen were increased (p<0.05) by the inclusion of FRGE3. Besides, redness ($a^*$) value for the breast meat was higher (p<0.05) in FRGE1 and FRGE3 treatments than that in CON. In laying hens, 240 ISA brown layers at 35 weeks of age were used in this 8-week trial. Dietary treatments were the same as in the broilers trial with 10 replicates per treatment and 6 layers per replicate. During the entire experiment, there were no significant differences (p>0.05) in performance or egg quality among all the treatments. However, the layers fed diets supplemented with FRGE had higher lymphocyte level (p<0.05) compared with those fed CON. In conclusion, the dietary supplementation with FRGE did not influence performance but improved the lymphocyte level in both broilers and laying hens.

• Asian-Australasian Journal of Animal Sciences
• /
• v.23 no.11
• /
• pp.1476-1481
• /
• 2010

This study was conducted to evaluate the effects of dietary supplementation with chito-oligosccharide (COS) on egg production, nutrient digestibility, egg quality and blood profiles in laying hens. A total of 240 Hy-line Brown laying hens were randomly allocated into one of the following 5 dietary treatments: i) CON, basal diet; ii) ANT, basal diet+44 mg/kg avilamycin; iii) COS0.2, basal diet+200 mg/kg COS; iv) COS0.4, basal diet+400 mg/kg COS; v) ANTCOS, basal diet+200 mg/kg COS+22 mg/kg avilamycin. The experiment lasted for 6 wk. No change in egg weight (p>0.05) was observed during the trial period. Egg production in ANTCOS treatment was improved (p<0.05) when compared to CON during weeks 4-6. The birds in the COS0.2, COS0.4 and ANTCOS groups had higher (p<0.05) Haugh unit than those fed CON and ANT diets at the end of the $6^{th}$ wk. The apparent digestibility of nitrogen in CON group was lower (p<0.05) than in other treatments. The white blood cell (WBC) concentration of birds in the COS0.4 and ANTCOS group was higher (p<0.05) than that of birds in other groups at the end of the $6^{th}$ wk. In addition, the differences of WBC counts between the beginning and end of the experiment in COS0.4 and ANTCOS groups were higher (p<0.05) than in CON and ANT groups. At the end of the experiment, the birds fed ANTCOS diet showed higher (p<0.05) total blood protein concentration than those fed CON or ANT diets. In conclusion, dietary supplementation of COS appeared to increase egg production and quality by increasing nutrient digestibility. Additionally, COS improved WBC and total protein concentration.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.33 no.6
• /
• pp.21-30
• /
• 2005

The aerodynamic analysis of helicopter rotor airfoils was performed to generate the basic data for selection and distribution of airfoils at the helicopter rotor blade preliminary design phase.10 airfoils were chosen among the existing rotor airfoils, and the tabulated aerodynamic coefficients which are proper for the aerodynamic analysis using blade element theory were generated. Considering analysis cost, the simple mathematical models were chosen before the wind tunnel test to generate the aerodynamic characteristic curves($C_{l},C_{m},C_{d}$) in full AoA range($-180^{o}\sim180^{o}$) including the reverse flow region. The essential data necessary to the generation of the complete curves were obtained by using the IBLM(Interactive Boundary Layer Method). The generated aerodynamic characteristic curves agree with experimental results qualitatively. Finally, the aerodynamic characteristics of all 10 airfoils were compared and classified according to their own lift or moment characteristics.

• Composites Research
• /
• v.28 no.3
• /
• pp.130-135
• /
• 2015

This study investigates the property of graphene filled polymer nanocomposites in LEO(Low Earth orbit) environment conditions. In order to improve compatibility with polymer matrices and resistance of carbon material against AO(Atomic oxygen) attack, silanization of graphene oxide with organosilane was carried out. The corresponding moieties were characterized through X-ray photoelectron spectroscopy (XPS). Graphene oxide filled nanocomposites were prepared using solution based processing methods. The sets of specimen series were tested in an accelerated LEO simulated space environment facility. Graphene oxide and silane treated graphene oxide reinforced nanocomposites were compared with neat epoxy. The comparison revealed that the silane treated graphene filled polymer composite shows inherent resistance against atomic oxygen attack while the lack of silane treatment resulted in a reduction in performance.

• Atmosphere
• /
• v.24 no.1
• /
• pp.111-122
• /
• 2014

In the Korea Meteorological Administration earth system model (HadGEM2-AO), cloud drop number concentration is determined from aerosol number concentration according to the observed relationship between aerosol and cloud drop number concentrations. However, the observational dataset used for establishing the relationship was obtained from limited regions of the earth and therefore may not be representative of the entire earth. Here we reestablished the relationship between aerosol and cloud drop number concentrations based on a composite of observational dataset obtained from many different regions around the world that includes the original dataset. The new relationship tends to provide lower cloud drop number concentration for aerosol number concentration < 600 $cm^{-3}$ and the opposite for > 600 $cm^{-3}$. This new empirical relationship was applied to the KMA earth system model and the historical run (1861~2005) is made again. Here only the 30 year (1861~1890) averages from the runs with the new and the original relationships between aerosol and cloud drop number concentrations (newHIST and HIST, respectively) were compared. For this early period aerosol number concentrations were generally lower than 600 $cm^{-3}$ and therefore cloud drop number concentrations were generally lower but cloud drop effective radii were larger for newHIST than for HIST. The results from the complete historical run with the new relationship are expected to show more significant differences from the original historical run.