• Ecology and Resilient Infrastructure
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• v.7 no.1
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• pp.1-14
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• 2020

In fluvial and riparian ecosystems, biogeomorphological research has considered the complex, multi-way relationships between biological and hydro-geomorphological components over a wide range of spatial and temporal scales. In this review, we discussed the scope and processes of fluvial biogeomorphology by explaining (1) the multi-lateral interactions between organisms and hydrogeomorphic conditions, (2) the relationships between biodiversity and habitat heterogeneity, and (3) the effects of disturbance on ecosystem patterns. Over time, an organism-landform complex along streams transitions in the sequences of geomorphic, pioneer, biogeomorphic, and ecological stages. Over space, water flow and sediment distributions interact with vegetation to modify channel topography. It is the habitat heterogeneity in streams that enhances riparian biodiversity. However, in the areas downstream of a dam, habitat types and conditions are substantially damaged and biodiversity should be reduced. In South Korea, riparian vegetation flourishes in general and, in particular, invasive species actively colonize in accordance with the changes in the fluvial conditions driven by local disturbances and global climate change. Therefore, the importance of understanding reciprocal relationships between living organisms and hydrogeomorphic conditions will ever increase in this era of rapid climate change and anthropogenic pressure. The fluvial biogeomorphic framework reviewed in this article will contribute to the ecological management and restoration of streams in Korea.

• Journal of the Korean Society of Food Science and Nutrition
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• v.41 no.8
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• pp.1106-1111
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• 2012

It is shown that the risk of chronic disease is increased not only by the concentration of fat in the diet but also by the composition of dietary fatty acids. We investigated the anti-oxidant effects of vitamin E on dietary polyunsaturated fatty acid-fed mice. Ninety male Sprague-Dawley rats were randomly divided into 9 groups: a normal diet group (C), 4 dietary polyunsaturated fatty acid diet groups (OA, LA, LNA, DHA), and 4 dietary polyunsaturated fatty acid diet with 0.05% vitamin E groups (OAE, LAE, LNAE, DHAE). The food efficiency in the dietary polyunsaturated fatty acid diet groups was higher than in the normal diet groups. The concentration of malondialdehyde (MDA) was significantly increased by LA and DHA fatty acids. Vitamin E significantly decreased LA and LHA-induced lipid peroxidation. The activity of superoxide dismutase and glutathione peroxidase was increased in the dietary polyunsaturated fatty acid diet groups compared to the control group, while these were decreased by supplements with vitamin E, except in the OAE group. Also, the protein expression of CYP2E1 was significantly increased in only the LNA group, while these were decreased by supplements with vitamin E. These results taken together indicate that vitamin E may have positive effects on a dietary polyunsaturated fatty acid diet-induced oxidative stress in brain tissue.

• Korean Journal of Materials Research
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• v.10 no.7
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• pp.493-498
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• 2000

The effects of RRA treatment on the microstructures and mechanical properties of 7050 Al alloy were investigated by differential scanning calolimetry, transmission electron microscopy, microhardness measurement and electrical conductivity. The hardness of 2nd-step aged specimen at $175^{\circ}C$ was decreased to mimimum value and increased to a peak hardness, and then re-decreased with retrogression treatment. It was found that the hardness of 2nd-step aged specimen was further increased by 3rd step aging treatment($120^{\circ}C$x24h). The initial decrease in hardness during 2nd-step aging was due to the partial dissolution of pre-existing GP zone, the major precipitation hardening phase at T6 condition. It was confirmed that the major precipitation hardening phase at 3rd-step aging was GP zone and η' phase. The electrical conductivity increased continually through 2nd-step and 3rd-step aging treatment. It was conclude that the optium 2nd-step aging condition was at $175^{\circ}C$ for 50min by considering the hardness and electrical conductivity.

• Journal of Energy Engineering
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• v.19 no.4
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• pp.221-227
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• 2010

In this study, we consider gas generation characteristics on pyrolysis of eco-fuel which were made by mixing of Pitch Pine and Lauan sawdust as biomass and polyethylene, polypropylene, polystyrene as municipal plastic wastes with catalyst in fixed bed reactor. From the result of higher heating value(HHV) measurement and of ultimate analysis, the heating value of plastic wastes and a hydrogen content in plastic sample are higher than biomass. An activation energy was reduced by a catalyst addition. However the catalyst content influence over 5 wt% was insignificant. The yield of hydrogen from gasification of biomass containing plastic wastes such as polyethylene, polypropylene and polystyrene were obtained higher than that of sole biomass. The high temperature and mixture ratio of catalyst conditions induced to high hydrogen yield in most of the samples. As the influence of catalyst, the hydrogen yield by catalytic reaction was higher than non-catalytic reaction. We confirmed that Ni-$ZrO_2$ catalyst is more active in increasing the hydrogen yield in comparison with that of carbonate catalyst. The maximum hydrogen yield was 65.9 vol.%(Pitch Pine / polypropylene / 20 wt.% Ni-$ZrO_2$(1:9) at $900^{\circ}C$).

• Journal of Energy Engineering
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• v.19 no.4
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• pp.240-245
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• 2010

In this study, characteristics of wood pellet gasification was studied using a Two Stage Gasifier which is consisted of pyrolysis reactor and ultra high temperature reformer. The average yields of $H_2$, $CH_4$, CO, $CO_2$ were 16.7, 11.3, 37.2, 26.6 L/mim, conversion rate from biomass to gas was 65% in pyrolysis reactor and gas yields in reformer were 55.4, 0.8, 120.8, 56.8 L/mim, respectively. The hydrogen flow rate from reformer is obtained 360.1 L/hr. The most of $CH_4$ was decomposed from 12.3 to 0.3 vol.% while $H_2$ is from 18.2 to 23.7 vol.% in reformer by methane dry reforming, Boudouard reaction, oxidation and/or steam reforming. The amount of $H_2O$ generated by hydration reaction from reformer was 1111.8 g, its accelerated conversion of $CH_4$ to other products. The conversion rate from $CH_4$ to other Compounds was 97.2%. Cold gas efficiency was 53.2%.

• Journal of Oriental Neuropsychiatry
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• v.18 no.2
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• pp.57-74
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• 2007

Objective : The purpose of this study was to investigate the anti-obesity and anti-hyperlipidemic Effects of Taeyeumjowee-tang and its modified prescription on the animal model of obesity and hyperlipidemia induced high-fat diet. Method : 1) The extracts of Taeyeumjowee-tang (TJT) and its modified prescription, Taeyeumjoweetang gagam-bang (TJGB) were evaluated for its inhibitory effects on obesity. 2) The body weight and feed weight were determined in the pre-treated and post-treated mice and the lipid profiles in the serum were analyzed in order to evaluate the anti-hyperlipidemia action of the extracts. 3) The effect of each extract was investigated for the influences on monoamine oxidase activity and HMG-CoA reductase activity. Results 1. TJT and TJGB extracts dose-dependently reduced the body weight and feed intake in normal mice. The effect of TJGB extract was better than that of TJT extract. 2. TJGB extract diminished the body weight increase and reduced the feed intake in the pre-treatment or post-treatment of the extract 3. TJGB extract decreased the amount of total cholesterol slightly and triglyceride potently after the pre-treatment or post-treatment, but HDL cholesterol exhibited no remarkable change compared with control. 4. TJGB extract weakly potentiated the monoamine oxidase activity, but its effect was better than that of TJT extract. 5. TJGB extract weakly inhibited the HMG-CoA reductase activity, but its effect was better than that of TJT extract. Conclusion : Taeyeumjowee-tang and its modified prescription can clinically be useful as anti-obesity drug and also for the improvement of hyperlipidemia.

• Journal of Korea Water Resources Association
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• v.39 no.10 s.171
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• pp.867-880
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• 2006

Hydrological models with many parameters and complex model structures require a powerful and detailed model calibration/validation scheme. In this study, we proposed a multi-variable and multi-site calibration and validation framework for the Soil Water Assessment Tool (SWAT) model applied in the Gap-cheon catchment located downstream of the Geum river basin. The sensitivity analysis conducted before main calibration helped understand various hydrological processes and the characteristics of subcatchments by identifying sensitive parameters in the model. In addition, the model's parameters were estimated based on existing data prior to calibration in order to increase the validity of model. The Nash-Sutcliffe coefficients and correlation coefficient were used to estimate compare model output with the observed streamflow data: $R_{eff}\;and\;R^2$ ranged 0.41-0.84 and 0.5-0.86, respectively, at the Heuduck station. Model reproduced baseflow estimated using recursive digital filter except for 2-5% overestimation at the Sindae and Boksu stations. Model also reproduced the temporal variability and fluctuation magnitude of observed groundwater levels with $R^2$ of 0.71 except for certain periods. Therefore, it was concluded that the use of multi-variable and multi-site method provided high confidence for the structure and estimated parameter values of the model.

• Ecology and Resilient Infrastructure
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• v.1 no.1
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• pp.8-18
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• 2014

This study analyzes characteristics of flow using 3 dimensional numerical model, Delft3D, at the downstream of hydraulic structure. And fish shelters are suggested by analyzing them in flood time. A hydraulic structure changes flow conveyance, water depth and velocity affecting the activity of the fish. Flow depth decreases and velocity is fast near the left bank at the downstream of Gumi weir because of the concentration of flow due to it. Therefore, fish shelters are generated near the right bank of it. As a result of vertical velocity distribution which indicates the range of fish activity, maximum value are 0.0043 m/s in 30-year of return period of flood 0.0052 m/s in 50 year flood, 0.0046 m/s in 80-year of return period of flood, and 0.0039 m/s in 100-year of return period of flood. As the discharge increases, the areas of fish shelters decreases because depth and turbulent energy increase according to increases discharge. The estimated areas of fish shelters near the right bank decrease from 61.5% in 30-year of return period of flood to 39.0% 100-year of return period of flood. Therefore, the constructed hydraulic structures affect fish shelters.

• Korean Journal of Environmental Agriculture
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• v.12 no.3
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• pp.230-238
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• 1993

To develop multifunctional microorganisms for effective wastewater treatment, the cell of P. aeruginosa P1 enable to accumulate lead in its cell were conjugated with the cell of P. fluorescens S1 enable to degrade efficiently synthetic detergents. The plasmids of the P. aeruginosa P1 and the P. fluorescens S1 were found in the cell of the conjugants when determined by agarose gel electrophoresis. The conjugants obtained from P. fluorescens S1 as a recipient cell and P. aeruginosa P1 as a donor cell possessed the ability to degrade synthetic detergents as well as to accumulate lead.

• Journal of Food Hygiene and Safety
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• v.35 no.4
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• pp.312-318
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• 2020

A method using liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed for neonicotinoid pesticide analysis in agricultural products. Four compounds (imidacloprid, clothianidin, acetamiprid, thiacloprid) were extracted with acetonitrile from agricultural products and cleaned up by NH₂ solid-phase extraction procedure, and eluted with 0.1% formic acid in methanol/dichloromethane (5/95, v/v). The limit of detection and quantification were 0.0001-0.0005 mg/kg and 0.001 mg/kg, respectively. The mean recoveries of neonicotinoid pesticide from agricultural products were in the range of 90.7-100.9% and 94.4-99.8%, as spiked at 0.2 mg/kg and 0.02 mg/kg, respectively. This validation satisfied the national criteria for pesticide analytical methods. In summary, The present method is fast, precise and sensitive enough for the Positive List System (PLS), and we conclude that the method is also suitable for neonicotinoid pesticide determination in a wide range of agricultural products.