• Korean Chemical Engineering Research
• /
• v.55 no.3
• /
• pp.332-340
• /
• 2017

This study aims to propose a new optimization-based approach for design and analysis of the stand-alone hybrid energy supply system using renewable energy sources (RES). In the energy supply system, we include multiple energy production technologies such as Photovoltaics (PV), Wind turbine, and fossil-fuel-based AC generator along with different types of energy storage and conversion technologies such as battery and inverter. We then select six different regions of Korea to represent various characteristics of different RES potentials and demand profiles. We finally designed and analyzed the optimal RES stand-alone energy supply system in the selected regions using multiobjective optimization (MOOP) technique, which includes two objective functions: the minimum cost and the minimum $CO_2$ emission. In addition, we discussed the feasibility and expecting benefits of the systems by comparing to conventional systems of Korea. As a result, the region of the highest RES potential showed the possibility to remarkably reduce $CO_2$ emissions compared to the conventional system. Besides, the levelized cost of electricity (LCOE) of the RES-based energy system is identified to be slightly higher than conventional energy system: 0.35 and 0.46 $/kWh, respectively. However, the total life-cycle emission of $CO_2$ ($LCE_{CO2}$) can be reduced up to 470 g$CO_2$/kWh from 490 g$CO_2$/kWh of the conventional systems.

• KSBB Journal
• /
• v.28 no.6
• /
• pp.372-379
• /
• 2013

This study was to investigate the chemical properties and nitrite scavenging and acetylcholinesterase inhibitory activities from Salicornia herbaciea seed. The lactic acid content of seed was about 2.0 fold higher than that of stem. Among various free sugars, the maximum fructose of seed, glucose of stem, and mannose contents of root were obtained, 176.3, 125.6, and 112.8 mg/100g, respectively. The maximum leucine content of seed among the essential amino acid was obtained, 853.7 mg/100g, which was about 3.0 or 6.0 folds higher than that of root or stem. In the case of glutamic acid of seed, it was 2,388.7 mg/100g, which was 5.6 or 9.8 folds higher han that of root or stem. The ratio of essential amino acid and total amino acid of seed was 30.14%. The ${\gamma}$-aminobutyric acid contents of seed, stem, and root were 43.87, 23.88, and 27.8 mg/100g, respectively. The catechin content of seed was an order of epigallocatechin (723.2 mg/100g) > epigallocatechingallate (654.3 mg/100g) > epicatechin (443.5 mg/100g) > gallocatechin (314.1 mg/100g). Especially, the non-gallated catechins content was about 2.0 folds higher than that of gallated catechins content. The nitrite scavenging activity of seed increased from 38.7 to 65.9% when the hot-water extract content of seed at pH 1.2 increased from 1.0 to 5.0 mg/mL. However, it was decreased to 25.7% at pH 6. The acetylcholinesterase inhibitory activity of seed was increased from 13.2 to 44.6% when the extract content increased from 20 to 100 mg/mL. These results show that S. herbaciea seed has a good potential to be used as a source of material or additive in cosmetics, food, and drug compositions.

• Journal of the Korea Convergence Society
• /
• v.10 no.12
• /
• pp.337-343
• /
• 2019

The need for preparation for old life has been further increased due to the increase of the elderly population and changes in economic conditions today. The purpose of this study is to analyze the relationship between income instability and the degree of preparation for old life and satisfaction of current life. The key variables were extracted through prior study review. And the data collected through the survey were statistically analyzed with a structural equation model. The analysis found that the indirect effect of the current income risk on the satisfaction of current life through the preparation for old life had a significant negative effect under the statistically significant level of 0.05. However, it was found that the direct effects of current income risk on the satisfaction of current life were not statistically significant. An additional analysis was conducted by dividing the age, the number of dependents by two groups respectively. To summarize the results, preparation for old life played a significant role as a prerequisite for improving the satisfaction of current life. And the variability(risk) of current income played an important role in preparing for old life. At this time, the degree of relevance between the factors(potential variables) differed somewhat between the two groups. The results of this analysis will be meaningful in providing basic source of data to prepare for a satisfactory life in each individual's current situation. This study, meanwhile, has limitations that have only been done with cross-sectional analysis and would like to analyze time-series changes in the future.

• Journal of the Korean Institute of Telematics and Electronics D
• /
• v.36D no.11
• /
• pp.56-62
• /
• 1999

All the cells on the whole memory array or a block of the memory array in the Flash EEPROM's are erased at the same time using Fowler-Nordheim (FN) tunneling. some of the cels are often overerased since the tunneling is not a self-limited process. In this paper, the optimum doping concentration of the floating gate solve the overerase problem has been studied. For these studies, N-type MOSFETs and MOS capacitors with various doping concentrations of the gate polysilicon have been fabricated and their electrical characteristics have been measured and analyzed. As the results of the experiment, it has been found that the overerase problem can be prevented if the doping concentration of the floating gate is low enough (i.e. below $1.3{\times}10^{18}/cm^3$). It is because the potential difference between the floating gate and the source is lowered due to the formation of the depletion layer in the floating gate and thus the erasing operation stops by itself after most of the electrons stored in the floating gate are extracted. On the other hand, the uniformity of the Vt and the gm has been significantly poor if the coping concentration of the floating, gate is too much lowered (i.e. below $1.3{\times}10^{17}/cm^3$), which is believed to be due to nonuniform loss of the dopants from the nonuniform segregation in the floating gate. Consequently, the optimum doping concentration of the floating gate to suppress the overerase problem and get the uniform Vt and has been found to range from $1.3{\times}10^{17}/cm^3$ to $1.3{\times}10^{18}/cm^3$ in the Flash EEPROM.

• Journal of Korean Society of Forest Science
• /
• v.99 no.6
• /
• pp.885-890
• /
• 2010

This study was conducted to confirm the application as ingredients of cosmetics through an examination of the function for anti-oxidant activity of the fraction isolated from Pyrus ussuriensis leaves. The dried leaf of Pyrus ussuriensis were extracted with acetone-$H_2O$ (6:4, v/v), concentrated and fractionated with the upper layer of acetone on a separatory funnel. Each fraction was freeze dried, then a portion of acetone soluble powder was chromatographed on a Sephadex LH-20 column using a series of aqueous methanol as eluents and also used the MIC-gel using a series of aqueous methanol as developing solvent. The isolated compounds were identified by silica-gel TLC. The concentration of total phenolic compound of Pyrus ussuriensis acetate soluble fraction was high, 914 mg/g. The results obtained from the analyses of the anti-oxidanat effects of Pyrus ussuriensis acetate fraction can be summarized as follows: In the result of DPPH scavenging radical activity, Pyrus ussuriensis acetate soluble fraction showed more than 80% at 100 ppm. SOD-like activity of one of Pyrus ussuriensis acetate soluble fractions was 77% at 1000 ppm. Xanthine oxidase inhibition of Pyrus ussuriensis acetate soluble fraction was 38% at 100 ppm. From these results, we confirmed that acetate fraction of Pyrus ussuriensis has a great potential as a natural ingredients with a natural antioxidant and antimicrobial source.

• Journal of Advanced Marine Engineering and Technology
• /
• v.38 no.9
• /
• pp.1045-1050
• /
• 2014

$N_2O$(Nitrous Oxide) is known as the third major GHG(Green House Gas) following $CO_2$(Carbon Oxide) and $CH_4$(Methane). The GWP(Global Warming Potential) factor of $N_2O$ is 310 times as large as that of $CO_2$ because $N_2O$ in the atmosphere is very stable, and it becomes a source of secondary contamination after photo-degradation in the stratosphere. Investigation on the cause of the $N_2O$ formation have been continuously reported by several researchers on power sources with continuous combustion form, such as a boiler. However, in the diesel engine, research on $N_2O$ generation which has effected from fuel components has not been conducted. Therefore, in this research, author has investigated about $N_2O$ emission rates which was changed by nitrogen and sulfur concentration in fuel on the diesel engine. The test engine was a 4-stroke direct injection diesel engine with maximum output of 12 kW at 2600rpm, and operating condition of that was set up at a 75% load. Nitrogen and sulfur concentrations in fuel were raised by using six additives : nitrogen additives were Pyridine, Indole, Quinoline, Pyrrol and Propionitrile and sulfur additive was Di-tert-butyl-disulfide. In conclusion, diesel fuels containing nitrogen elements less than 0.5% did not affect $N_2O$ emissions in the all concentrations and kinds of the additive agent in the fuel. However, increasing of the sulfur additive in fuel increased $N_2O$ emission in exhaust gas.

• Journal of Physiology & Pathology in Korean Medicine
• /
• v.28 no.2
• /
• pp.178-185
• /
• 2014

Leonuri Fructus, a semen of Leonuri Herba, has been used for the treatment of menstrual disorders such as amenorrhea, dysmenorrhea and leukorrhea and for the remedy of hyperemia. The present study was conducted to evaluate the anti-inflammatory effects of the Leonuri Fructus extract (Leonurus japonicus Houtt. EtOH extract; LJE) in vivo and in vitro. In vitro study, the MTT assay for cell viability was conducted to determine the non-cytotoxic concentration of LJE treatment in media. The levels of NO were measured with Griess reagent. Pro-inflammatory cytokines were detected by ELISA method. The inflammation-related proteins of this study were detected by immunoblot anlaysis. The increases of NO production and iNOS expression were detected in LPS-treated cells compared with control, but LJE attenuated the increases of NO and iNOS by LPS. LJE reduced the production of TNF-${\alpha}$ and IL-$1{\beta}$ induced by LPS stimulation. LJE suppresses the signaling pathways of NF-${\kappa}B$ and MAPKs in LPS-induced macrophage cells. In vivo study, carrageenan-induced hind paw acute edematous inflammation rat model was used for evaluation of anti-inflammatory activity of LJE. LJE significantly inhibited the increases of hind paw swelling, skin thicknesses and inflammatory cell infiltrations, and decreased the numbers of mast cell induced by carrageenan injection. These results suggest that LJE has an anti-inflammatory therapeutic potential, which is mediated through modulating NF-${\kappa}B$ activation and MAPK phosphorylation. Inhibition of the rat paw edema induced by carrageenan is considered as direct evidence that LJE may be a useful source to treat inflammation.

• Journal of Life Science
• /
• v.27 no.3
• /
• pp.351-354
• /
• 2017

Cowpea (Vigna unguiculata (L.) Walp.) is recognized as a potential source of protein and other nutrients. The genus Vigna includes 100 wild species of plants. Especially, Vigna unguiculata includes annual cowpeas (ssp. unguiculata) and ten wild perennial subspecies. DNA sequence of internal transcribed spacer (ITS) region was determined for Vigna sinensis, one of native plant, which was found in recent but thought to have gone extinct in Korea. The seeds of Vigna sinensis used in this study were donated from Dong-Young Jo. The DNA sequence of ITS-5.8S-ITS2 for Vigna sinensis obtained from this study was deposited as Vigna sinensis AY195581 on GenBank of NCBI (National Center for Biotechnology Information). We investigated the sequence-based phylogenetic relationships of plants related and clarified its taxonomical position. DNA similarities among subspecies including Vigna unguiculata showed the range 98 to 100% in sequence-based phylogenetic analysis using total 507 base pairs of ITS1, 5.8S and ITS2. Vigna unguiculata and subspecies were grouped independently as one cluster from other Vigna species used in the phylogenetic analysis. In this study, based on the phylogenetic analysis using the ITS1-5.8S-ITS2 sequence of Vigna sinensis, it may be concluded to be classified to one of Vigna unguiculata substrains.

• Journal of Life Science
• /
• v.30 no.5
• /
• pp.452-459
• /
• 2020

This study was conducted to investigate the total lignin content and anti-oxidant activity in extracts of defatted sesame seeds (DSS) fermented with 15 strains of Bacillus subtilis. The anti-oxidant activities of DSS were analyzed both before and after fermentation. The total lignan content of the DSS extracts fermented with BCH3678 (1,613.8 mg/l) and BCH3572 (1,599.5 mg/l) were relatively high compared to other strains. Anti-oxidant activity was determined according to phenolic compound and flavonoid content and DPPH radical scavenging rate; the highest total phenolic compound content was provided by the DSS with SRCM103716 at 2,803.3 mg GAE/g which returned total flavonoid content of 1,553.1 mg/g as strong correlation of its anti-oxidant activity. The DSS extract fermented by SRCM103716 at 37℃ for 24 hr showed the highest DPPH scavenging rate at 66.5%. The fermented DSS extracts, regardless of strain, demonstrated higher anti-oxidative activity than the unfermented control, and these results suggest that such extracts could be useful as a potential source of bioactive compounds.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.25 no.2
• /
• pp.42-53
• /
• 2020

In this study, heavy metal in road-deposited sediments (RDS) and marine sediment around Gwangyang Bay area have been investigated to assess the pollution status of metals and to understand the environmental impact of RDS as a potential source of metal pollution. Zn concentration for <63 ㎛ size fraction was the highest (2,982 mg/kg), followed by Cr, Ni, Pb, Cu, As, Cd, and Hg. Metal concentrations in RDS increased with decreasing particle size and relatively higher concentrations were observed around the metal waste and recycling facilities. For particle size in RDS smaller than 125 ㎛, EF values indicated that Zn was very high enrichment and Cr, Cd, Pb were significant enrichment. The concentrations of metals in marine sediments were mostly below the TEL value of sediment quality guidelines of Korea. However, the Zn concentrations has increased by 30~40% compared to 2010 year. The amounts of Zn, Cd and Pb in less than 125 ㎛ fraction where heavy metals can be easily transported by stormwater runoff accounted for 54% of the total RDS. The study area was greatly affected by Zn pollution due to corrosion of Zn plating materials by traffic activity as well as artificial activities related to the container logistics at Gwangyang container terminal. The fine particles of RDS are not only easily resuspended by wind and vehicle movement, but are also transported to the surrounding environments by runoff. Therefore, further research is needed on the adverse effects on the environment and ecosystem.