• Journal of the Korean Institute of Gas
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• v.23 no.6
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• pp.90-96
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• 2019

Natural gas has been regarded as one of major alternative fuels, because of the increment of mining shale gas and supplying PNG(Pipeline Natural Gas) from Russia. Thus, it needs to broaden the usage of natural gas as the increasing its supplement. In this situation, application of natural gas on the transport area is a good suggestion to reduce exhaust emissions such as CO₂(carbon dioxides) and soot from vehicles. For this reason, natural gas can be applied to SI(spark ignition) engines due to its anti-knocking and low auto-ignitibility characteristics. Recently, since turbocharged SI engine has been widely used, it needs to apply natural gas on the turbocharged SI engine. However, there is a major challenge for using natural gas on turbocharged SI engine, because it is hard to make natural gas direct injection in the cylinder, while gasoline is possible. As a result, there is a loss of fresh air when natural gas is injected by MPI (multi-point injection) method under the same intake pressure with gasoline-fueled condition. It brings the power reduction. Therefore, in this research, intake pressure was increased by controling the turbocharger system under natural gas-fueled condition to improve power output. The goal of improved power is the same level with that of gasoline-fueled condition under the maximum torque condition of each engine speed. As a result, the maximum power levels, which are the same with those of gasoline-fueled conditions, with improved brake thermal efficiency could be achieved for each engine speed (from 2,000 to 6,000 rpm) by increasing intake pressure 5-27 % compared to those of gasoline-fueled conditions.

• Journal of the Korea Organic Resources Recycling Association
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• v.13 no.4
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• pp.89-99
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• 2005

The golf courses more than about 200 are operating in Korea. From the golf courses, a great amount of turfgrass clippings tend to increase, steadily. Materials used in the experiment were Creeping Bentgrass(CB), Kentucky Bluegrass(KB), Korean Lawngrass(KL), rice bran and composted chicken drop. Treatments are CB, KB, and KL. The temperature during the composting of all treatments increased rapidly and reached at the highest temperature($57.9^{\circ}C$, $67.8^{\circ}C$, $74.3^{\circ}C$) within 20 days, and then stabilized to the range of $35.2{\sim}41.6^{\circ}C$ at the 30th day. The pH values of all treatments decreased on the first day. However, they were increased rapidly after three days and decreased again on 10~20 days. The pH values of all treatments at the final day were stabilized to the low alkali levels. The contents of total carbon during the period of composting tend to decrease and total nitrogen was increased for factor of reduction of volume. CEC value of all treatments during the period of composting tends to increase. The round paper chromatogram of extracted solution of KL sample was the sharpest and clearest among all treatments. The G.I. values of CB, KB, and KL in 30th day of composting were about 95.1, 77.7, and 98.7 in germination test using chinese cabbage, respectively. Conclusively, all turfgrass clippings used in this experiment were composted well, suitable as composting products standardized by KSC. The maturity of the final compost samples is best in KL, followed by CB and KB treatments. The turfgrass compost can contribute to the plant cultivation for environment-friendly farm, and the results of this study can become the basic data of turfgrass clippings compost. Further research on the mixing ratio of each material is required to produce compost of good quality.

• The Korean Journal of Mycology
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• v.40 no.1
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• pp.54-59
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• 2012

This study investigates the effect of ${\beta}$-glucans on the growth of Caenorhabditis elegans. Comparison was made among lipopolysaccharide (LPS) and ${\beta}$-glucans extracted from Phellinus baumii, in the presence of peptidoglycans which is available as the major carbon source from OP50, a non-pathogenic strain of Escherichia coli. When the three sources of carbohydrate were added singularly or in mixture to the culture media, a significant level of variation was observed with respect to fecundity. Addition of ${\beta}$-glucans appeared to increase the fecundity. When ${\beta}$-glucans was reinforced in the culture media, the fecundity increased at least 20 percent compared to the OP50-only media which exclusively contains peptidoglycans. In terms of life span, C. elegans showed a modest reduction when treated especially with ${\beta}$-glucans. C. elegans accumulated less fat in the ${\beta}$-glucans containing media different from the OP50 media. Based on the Sudan black staining, fat deposition significantly decreased corresponding to the ${\beta}$-glucans content in the media. On LPS-supplemented media, no difference was observed in fat deposition compared to the normal OP50 media. At the level of motility, ${\beta}$-glucans-treated worms moved more distance as well as LPS-treated worm. They also showed a comparable degree of motility under similar treatment with each source of carbohydrate. In conclusion, LPS and ${\beta}$-glucans, extracted from P. baumii, may not entirely replace the food required for C. elegans; however, it might be utilized as valuable alternative food source which C. elegans use as forms of carbohydrates in stead of peptidoglycan of OP50.

• Journal of Wetlands Research
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• v.20 no.2
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• pp.161-172
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• 2018

A mixed farming system that includes organic rice production and freshwater fish farming is being called into attention in Korean agricultural industry and rural areas in order to improve farm management and environmental conservation. This study was conducted to evaluate the environmental and ecological value of such mixed farming practices. Expert assessment and rapid assessment method (RAM) of wetland evaluation were employed for this study. Experts have responded that biodiversity conservation including amphibian and reptile habitat (2.39), aquatic insect habitat (2.36), Fishery habitat (2.34), vegetation diversity (2.13), avian habitat (2.05), and experience and education were the most important function of mixed farming. The wetland function evaluation conducted using modified RAM indicated that rice-fish mixed system showed improvements in most of the evaluated functions, compared to the conventional rice paddies. The overall wetland function of rice paddies in rice-fish mixed system was greatly improved as compared with the conventional rice paddies. Rice paddies are known to play an important role in biodiversity maintenance, and provide ecosystem services such as climate modulation and carbon reduction. Rice-fish mixed system of farming may not only improve various ecosystem services of rice paddies, but may increase farm income through value added fish farming, as well as promotion of social services such as education and maintenance of tradition. Additional research is needed for quantitative analysis of the values gained from the most improved wetland function when mixed farming system is actually put into practice, and to utilize the results in advertising of the organic rice, and in various sectors such as food, education and direct payment policy.

• Korean Journal of Microbiology
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• v.48 no.3
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• pp.180-186
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• 2012

Pseudomonas aeruginosa, a Gram-negative bacterium, is an ubiquitous and opportunistic human pathogen, which expresses many virulence factors through quorum sensing (QS) regulation. QscR, one of the QS signal receptors of P. aeruginosa, has unique features that make it possible to distinguish QscR from other QS receptors. In the present study, we focused on amino acid residues responsible for such a broad signal specificity of QscR. Thus we constructed mutant QscRs: $QscR_{T72I}$, $QscR_{R132M}$, and $QscR_{T140I}$ by substituting $72^{nd}$ threonine, $132^{nd}$ arginine, and $140^{th}$ threonine residues with isoleucine, methionine, and isoleucine, respectively by site-directed mutagenesis. When we examined the activity of these mutant QscRs, $QscR_{R132M}$ failed to respond to N-3-oxododecanoyl homoserine lactone (3OC12-HSL), but $QscR_{T72I}$ and $QscR_{T140I}$ remained the ability to respond to 3OC12-HSL despite much reduction of the sensitivity. When we treated a variety of acyl-HSLs with different structure, $QscR_{T72I}$ and $QscR_{T140I}$ showed better responsiveness to N-decanoyl HSL (C10-HSL) or N-dodecanoyl HSL (C12-HSL) that has no oxo-moiety at $3^{rd}$ carbon of acyl group than to 3OC12-HSL, and $QscR_{R132M}$ showed no responsiveness to any acyl-HSLs tested here. In addition, $QscR_{T72I}$ and $QscR_{T140I}$ were inhibited by 5f, a QscR inhibitor as similarly as wild type QscR was. These results suggest that while the $130^{th}$ arginine is crucial in both activity and acyl-HSL binding of QscR, the $72^{nd}$ and $140^{th}$ threonines are important in the activity, but they are little responsible for the discrimination of acyl-HSLs or competitive inhibitor.

• Applied Biological Chemistry
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• v.19 no.2
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• pp.104-111
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• 1976

The experiment was tested with fruit of 5 astringent cultivars (Chungdo-Bansi, Sagoksi, Euisung-Bolbansi and Gyungsan-bansi) and was carried out to investigate effects of harvest time of fruit and fruit sizes on the removal of astringency and the practical utilization with Chungdo-Bansi was conducted. 1. Soluble tannin content was decreased in all cultivars as fruit was ripening and soluble tannin content at last harvest time was reduced about one half, as contrasted it's content at first harvest time and it showed that the times required of the removal of astringency was gradually shortened. 2. In soluble tannin contents was small fruit size was significantly higher than that of large fruit size. The times for the removal of astringency was required longer small fruit size than large fruit size. 3. In the changes of hardness according to fruit sizes, hardness of large fruit size was decreased rapider than that of small fruit size. This tendency became similar during and after the removal of astringency. 4. According to fruit sizes, sugar content of large fruit size was more amount than that of small fruit size During and after the removal of astringency, reduction of sugar content showed more rapidly large fruit size than small fruit size. 5. Results of the practical utilization in Chungdo-Bansi showed the promising market-ability and persimmons treated by carbon dioxide was increased more income than that treated by $CaC_2$.

• Clean Technology
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• v.13 no.1 s.36
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• pp.54-63
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• 2007

Even traces of CO in the hydrogen-rich feed gas to proton exchange membrane fuel cells (PEMFC) poison the platinum anode electrode and dramatically decrease the power output. In this work, a variety of catalytic materials consisting of $Cu/Ce_xZr_{1-x}O_2$, (x = 0.0-1.0) were synthesised, characterized and tested for CO oxidation and preferential oxidation of CO (PROX). These catalysts prepared by hydrothermal and deposition-precipitation methods. The catalysts were characterized by XRD, XRF, SEM, BET, $N_2O$ titration and oxygen storage capacity (OSC) measurement. The effects of composition of the support and degree of excess oxygen were investigated fur activity and $CO_2$ selectivity with different temperatures. The composition of the support markedly influenced the PROX activity. Among the various $Cu/Ce_xZr_{1-x}O_2$ catalysts having different composition, $Cu/Ce_{0.9}Zr_{0.1}O_2$ and $Cu/Ce_{0.7}Zr_{0.3}O_2$ showed the highest activities (>99%) and selectivities (ca.50%) in the temperature range of $150{\sim}160^{\circ}C$. It was found that by using of $Ce_xZr_{1-x}O_2$ mixed oxide support which possesses a high oxygen storage capacity, oxidation-reduction activity of Cu-based catalyst was improved, which resulted in the increase of catalytic activity and selectivity of CO oxidation in excess $H_2$ environments.

• Korean Journal of Weed Science
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• v.11 no.2
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• pp.128-136
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• 1991

This experiment was conducted to evaluate the effect of plant growth regulators, dichlorprop and MCPB on the reduced effect of fruit drop and fruit quality before and after storage in apples. Dichlorprop was tested with dilution of 1000 at 30, 40, 50 days before harvesting, and MCPB with dilution of 4000 at 15, 25, 35 days before harvesting. The results are summarized as follows : Percentage of fruit drop was appeared to the notable reduction as compared with the untreated control when regulators was applied with dilution of 1000 at 30 days before harvesting by dichlorprop and with dilution of 4000 at 35 days before harvesting by MCPB. Degree of fruit colour showed to the remarkable promotion at all the treatment of 30, 40, 50 days before harvesting by dichlorprop as compared with the untreated control. Sugar contents in flesh was increased a little at the treatment of 30 days before harvesting by dichlorprop, but acid contents in flesh was reduced at all the treatment of 30, 40, 50 days before harvesting by dichloroprop and at 15, 25, 35 days before harvesting by MCPB. Passed firmness of fruit after storage was maintained at the treatment with dilution of 4000 at 35 days before harvesting. Therefore, it was repressed a softening of fruit, but by dichlorprop treatment at 30, 40, 50 days before harvesting, fruit firmmess was appeared to reduce according to the passage of storage period. Amount of ethylene evolution after storage was showed to reduce at all the treatment by early treated time of dichoroprop and MCPB, but carbon dioxide increased at treatment conditions such as the front. Accordingly, these relationship showed to be contrary each other.

• Journal of Conservation Science
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• v.32 no.4
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• pp.579-588
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• 2016

This study analyzed nonmetallic inclusions in iron swords with a ring pommel excavated in the Ipbuk-dong, Suwon. Scanning electron microscopy with energy dispersive spectroscopy(SEM-EDS) was used to estimate the iron-making temperature, and we compared the oxide with $SiO_2$ to investigate the heat-treatment technology in the production of iron swords with a ring pommel by investigating the artificial insertion of a slag former and the metallurgical structure. From the wustite observed in most of the specimens, it is judged that these swords were produced by heating and forging iron smelted at a low temperature using the solid reduction method. In addition, judging from the partial presence of $P_2O_5$, it is assumed that they were smelted directly with natural ore, not calcined. From the ratios of $CaO/SiO_2$ and $TiO_2/SiO_2$, it is judged that the raw material for iron-making was iron ore and that a calcareous slag former was not artificially inserted. The structure of the blade part on the front end was pure iron. From the high carbon content of the blade part on the ring pommel and the formation of a martensitic structure and pearlite colony, it is judged that they were tempered after carburizing and that the back, handle part, and ring pommel were unintentionally carburized. Judging from the structure of these specimens, it was noted that they were produced by applying artificial partial heat-treatment technology. This study attempted to present a more scientific analysis by using the method of interpretation through component analysis of nonmetallic inclusions appearing in one relic by the ratio of the oxide divided by $SiO_2$. It is judged that reinterpreting the arguments by the results of the existing analysis and research in this way can obtain different interpretations.

• Journal of the Korean Chemical Society
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• v.36 no.2
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• pp.261-272
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• 1992

Tetradentate Schiff base Cobalt(II)(3MeOSED)$(H_2O)_2$ complexe was synthesized and allowed to react with dry oxygen to form oxygen adducts of Cobalt(III) complexes such as ${\mu}$-peroxo type [Co(III)(3MeOSED)(DMF)]$_2O_2$ and [Co(III)(3MeOSED)(DMSO)]$_2O_2$in DMF and DMSO or superoxo type [Co(III)(3MeOSED)(Py)]$O_2$ in pyridine. The oxygen adducted complex was investigated by cyclic voltammetry and DPP method with glassy carbon electrode in 0.1M TEAP-DMF (-DMSO,-Py) as supporting electrolyte solution. As a result the reduction reaction process occurred to four steps including prewave Of $O_2^-$in 1 : 1 oxygen adducted superoxo type [Co(III)(3MeOSED)(Py)]$O_2$complex and three steps not including prewave of $O_2^-$ in 1 : 2 oxygen adducted ${\mu}$-peroxo type [Co(III)-(3MeOSED)(DMF)]$_2O_2$ and [Co(III)(3MeOSED)(DMSO)]$_2O_2$. A superoxo type [Co(III)(3MeOSED)(L)]$O_2\;(L: CH_3OH)$ was generated with oxygen in methanol. Selectively oxidized hydrazobenzene $(H_2AB)$ to trans-azobenzene(t-AB) and the rate constant k for oxidation reaction of the following equation is $(2.96 {\pm} 0.2)$${\times}$ $10^{-1}$M/sec. $H_2AB$ + Co (II)(3MeOSED)$(L_2)+O_2\;{\rightleftarrow^K}$ [Co(III)(3MeOSED)(L)]$O_2{\cdot}H_2AB{\longrightarrow^K}$ Co(II(3MeOSED)$(L)_2$+t-AB+$H_2O_2 $.