• Korean Chemical Engineering Research
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• v.51 no.6
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• pp.766-773
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• 2013

A transparent film was fabricated based on bacterial cellulose (BC), BC has excellent physical strength and stability at high temperature and it is an environmental friendly flexible material. In order to improve the conductivity, silver nanowire (AgNW) and/or graphene were introduced to the BC membrane. The aspect ratio of the AgNW synthesized in this study was 214, with a length of $15{\mu}m$ and width of 70 nm. The higher aspect ratio improved the conductivity by reducing the contact resistance. The thermal and electrical properties of 7 types of films prepared were investigated. Each film was fabricated with rectangular shape ($2mm{\times}2mm{\times}50{\mu}m$). The films were scored with a net shape by a knife, and filled with AgNW and graphene to bestow conductivity. The film filled with AgNW showed favorable electrical characteristics with a thickness of $350{\mu}m$, electron concentration of $1.53{\times}10^{19}$, electron mobility of $6.63{\times}10^5$, and resistivity of 0.28. The film filled with graphene had a thickness of $360{\mu}m$, electron concentration of $7.74{\times}10^{17}$, electron mobility of 0.17, and resistivity of 4.78. The transmittances at 550 nm were 98.1% and 80.9%, respectively. All the films were able to light LEDs bulbs although their brightness differed. A thermal stability test of the BC and PET films at $150{\pm}5^{\circ}C$ showed that the BC film was more stable, whereas the PET film was quickly banded. From these results, it was confirmed that there it is possible to fabricate new transparent conductivity films based on BC.

• Environmental and Resource Economics Review
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• v.14 no.1
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• pp.167-199
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• 2005

The following policy implications can be drawn from this study: 1) The Air Pollution Emission Amount Report published by the Ministry of Environment since 1991 classifies industries into 4 sectors, i. e., heating, manufacturing, transportation and power generation. Currently, the usability of report is very low and extra efforts should be given to refine the current statistics and to improve the industrial classification. 2) Big pollution industries are as follows - s7, s17 and s20. The current air pollution control policy for these sectors compared to other sectors are found to be inefficient. This finding should be noted in the implementation of future air pollution policy. 3) s10 and s17 are found to be a big polluting industrial sector and its pollution reduction effect is also significant. 4) The effect of emission coefficient (${\Delta}f$) has the biggest impact on the reduction of emission amount change and the effect of economic growth coefficient (${\Delta}y$) has the biggest impact on the increase of emission volume. The effect of production technology factor (${\Delta}D$) and the effect of the change of the final demand structure (${\Delta}u$) are insignificant in terms of the change of emission volume. 5) Further studies on emission estimation techniques on each industry sector and the economic analysis are required to promote effective enforcement of the total volume control system of air pollutants, the differential management of pollution causing industrial sectors and the integration of environment and economy. 6) Korea's economic growth in 1990 is not pollution-driven in terms of the Barry Commoner's hypothesis, even though the overall industrial structure and the demand structure are not environmentally friendly. It indicates that environmental policies for the improvement of air quality depend mainly on the government initiatives and systematic national level consideration of industrial structures and the development of green technologies are not fully incorporated.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.6
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• pp.715-721
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• 2007

Residual calcium concentration is high, in general, at the effluent of the fluoride removal process in the electronics industry manufacturing semiconductor and LCD. To increase the stability of the membrane process incorporated for reuse of wastewater, the residual calcium is required to be pre-removed. Hyperkinetic Vortex Crystallization(HVC) process was installed in the electronics industry manufecturing semi conductor as a pilot scale for accelerating calcification of calcium ion. Compared to the conventional soda ash method, the 31% higher calcium removal efficiency was achieved when HVC was applied at the same sodium carbonate dosage. In order to maintain the economic calcium removal target of 70% preset by manufacturer, the dosing concentration of the soda ash was 530 mg/L based on influent flowrate. The seed concentration in the reactor was one of the critical factors and should be maintained in the range of $800\sim1,200mg$ SS/L to maximize the calcium removal efficiency. The calcite production rate was 0.30 g SS/g $Na_2CO_3$ in the average. The economic HVC passing time of the mixture was in the range of $2\sim5$ times. Relatively, stable calcium concentration was maintained in the range of $30\sim72$ mg/L(average 49 mg/L) although the calcium concentration in the feed was severely fluctuated with $74\sim359$ mg/L(average 173 mg/L). The HVC process was characterized as environment-friendly technology reducing chemical dosage and chemical sludge production and minimizing maintenance cost.

• Korean Journal of Environmental Agriculture
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• v.33 no.3
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• pp.149-154
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• 2014

BACKGROUND: To evaluate the application level of expeller cake fertilizer(ECF), we have investigated soil chemical properties, leaf mineral contents and yield of tah tasai Chinese cabbage in a plastic film greenhouse. METHODS AND RESULTS: Five levels of fertilizer were applied as 0%(ECF 0), 50%(ECF 50), 75%(ECF 75), 100% (ECF 100) and 150%(ECF 150) by base 1,848 kg/ha of ECF. In 2012, tah tasai Chinese cabbage was planted on April 28 in a silt loam soil and harvested on July 12. Commercial yields were measured 10 times from May 10 to July 12. Electrical conductivity (2.24~3.09 dS/m), available $P_2O_5$(484~581 mg/kg) and exchangeable cations($K^+$, $Ca^{2+}$ and $Mg^{2+}$) were tended to increase by the application of ECF. However, the range of those was not significant. The contents of T-N, K, Ca and P of tah tasai Chinese cabbage leaves were 62.2~66.5 g/kg, 44.3~48.7 g/kg, 5.1~5.9 g/kg and 5.6~6.2 g/kg, respectively. The nitrogen utilization rate of tah tasai Chinese cabbage was 39.4~51.6%, and it was decreased with increased application amount of ECF. The yield of tah tasai Chinese cabbage was 9,806 to 12,730 kg/ha on the basis of application amount of ECF and it was not increased in spite of increased ECF. CONCLUSION: The optimum dose of application of ECF for cultivation of tah tasai Chinese cabbage was ranged from 924 kg/ha(as ECF 50) to 1,386 kg/ha(as ECF 75). Environment-friendly and economical amount of applied fertilizer is more important than yield for cultivation of tah tasai Chinese cabbage.

• The Korean Journal of Pesticide Science
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• v.16 no.2
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• pp.121-130
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• 2012

In analyzing pesticide residue, LLE (liquid liquid extraction) is generally applied as one of the existing methods, but needed quite a lot of organic solvents and analytical apparatuses for the sample pre-treatment. In addition to its long analysis time and complex analytical processes, it is required to develop a more rapid and efficient method at present. In order to establish an economic and simple pesticide residue analytical method, this study carried out a comparative experiment on the existing analytical method with a new sample pre-treatment method named QuEChERS (quick, easy, cheap, effective, rugged and safe), which extracts and refines pesticide components by directly adding solid powder into the sample. Both the two analytical methods showed favorable values of correlation coefficient ($R^2$ > 0.99) of calibration curves. In terms of the detection limit (identification limit), imidacloprid showed 0.02 mg/kg, while the rest of pesticides showed a level around 0.05 mg/kg. The results of this experiment revealed that the recovery of LLE was 92.8-100.9% and the RSD was below 2.5%. On the other hand, the recovery of QuEChERS was 92.2-101.6% and RSD was below 1.9%. As a result of comparing the amount of pesticide residue by the time between the two analytical methods by using Paired t-Test, there was no significant difference between the two analytical methods as the p-value ranged from 0.3148-0.9890. Considering the results of the two methods, the QuEChERS method had similar recovery, compared to the analytical method using the existing LLE, and the analytical time was shortened by about one fourth of that of the existing method. Moreover, since it excludes the use of harmful organic solvents like dichloromethane during the process of extraction, thus leading to protecting experimenters health and remarkably reducing the amount of disused solvents, it is judged as an echo-friendly and economic analytical method.

• Korean Journal of Organic Agriculture
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• v.20 no.4
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• pp.535-542
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• 2012

This study was carried out from 2011 to 2012 in order to analyze the cultivation technology system by six organic rice cultivation types in the southern provinces for the purpose of utilizing organic rice farming guidelines. This surveys were conducted by site visit on 8 counties and 115 farms in southern area. Cultivation technology system by six organic rice cultivation types were cultivated by the principle of minimum input or non-input. cropping systems, a mixture of barley and rice, or rice green manure crops were grown. Cultivars were mixture of the local cultivars and Japanese varieties. Soil were managed by a self-manufactured compost, indigenous microorganisms and barley straw without any fertilization. Pest control was mainly practied by purchased eco-friendly organic materials or herbal medication residue and indigenous microbial self-manufactured. Weed was controled by snails and barley straw. In addition, considering the restore of a longtail pitching shrimp and grasshoppers, the fuction of environmental ecology of six organic rice cultivation type proved to be excellent all. Meanwhile, the productivity of the organic farming per 10a were the order of Life and environment > Natural circulation > Stevia > Ji jang > Art and nature > Taepyoung of Farming Methods, but the farmers received prices showed the opposite tendency. Simple profitablity did not show a big difference. But, the productivity of all type of the organic farming were lower then the conventional farming. Finally, If we want to conduct safety and easy farming, we can suggest stevia farming, Natural circulation farming and life and environmental farming out of 6 organic rice cultivation types.

• Korean Journal of Environmental Agriculture
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• v.39 no.1
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• pp.1-9
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• 2020

BACKGROUND: The aim of this study was to investigate the soil chemical properties and soil bacterial community of the cropping system for Cnidium officinale Makino. METHODS AND RESULTS: The bacterial community was analyzed for the relative abundance and principal coordinated analysis (PCoA analysis) by using by Illumina Miseq sequencing. The correlation analysis between soil chemical properties and soil bacterial community were analyzed by Spearman's rank correlation and DISTLM analysis. Soil bacterial community (phylum and class) showed two distinct clusters consisting of cluster 1 (first cropping) and cluster 2 (continuous cropping) from 2 different cultivation methods of Cnidium officinale Makino. PCoA and DISTLM analyses showed that soil pH and Ca significantly affected soil bacterial community in cultivation area of Cnidium officinale Makino. In addition, Spearman's rank correlation showed significant correlation between relative abundance (Acidobacteria and Actinobacteria) and soil factors (soil pH and Ca). CONCLUSION: The results of this study were considered to be important for determining the correlation between soil properties and soil bacterial community of the cropping method for Cnidium officinale Makino. Furthermore, the results will be helpful to investigate the cause of continuous cropping injury of the Cnidium officinale Makino by examining the changes of soil properties and soil bacterial communities.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.10 no.6
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• pp.139-151
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• 2007

To protect the surface of ground-cutting slopes and ground-raised slopes and to recover environment-friendly slopes at the national road expansion construction between Gamchon and Yaechon, test-construction work was done using several modes of hydro-seeding measures to select a suitable construction method through the field survey; the results were as follows : As a result of survey on physio-chemical characteristics of soil, the average soil inclination on ground-raised slopes was from 4.73 mm to 5.37 mm; the average soil acidity was from pH 6.47 to 6.73; the average soil humidity was within the scope of 0.57~1.70 %,; the average soil inclination on ground-cutting slopes was 9.17~10.43mm; the average soil acidity was pH 6.67~6.77 and the average soil humidity was within the scope of 0.53~1.27 %; considered overall, they showed generally satisfactory base materials for plant breeding. As a result of the number of sprouting individuals, the average sprouting number of individuals on test spots executed by Coir net with Seed spray construction methods and the average number of sprouting individuals on other test spots executed by furrow-digging with Seed spray and Straw mat-mulching measures were 1,172 number of per square meter and 970 number of per square meter respectively; thus they showed higher numerical value comparing with other test spots. Likewise, the average number of sprouting individuals on test spots of the ground-cutting slopes executed by Coir net with Seed spray method and the average number of sprouting individuals on other test spot executed by furrow-digger with Seed spray and Straw mat-mulching measures were found to be 1,107 number of per square meter and 1,105 number of per square meter respectively, whose numerical value showed rather higher other test spots. As a result of a survey on living plants' breeding index [dried weight], the weight in dried state on test spots executed by Coir net with Seed spray method and other test spots executed by furrow-digger with Seed spray and Straw mat-mulching measures on both ground-raised and ground-cutting slopes was found to be higher and showed similar characteristics statistically. As a result of survey on the surface-covering degree of ground-raised slopes, nine weeks after test construction, test spots executed by Coir net with Seed spray method and other test spots executed by furrow-digger with Seed spray and Straw mat-mulching measures showed commonly more than 70% of surface-covering degree, but other test spots showed only below 35% of surface covering degree; especially in case of test spots by Verdvol seed spray measures, they showed 10% of the lowest surface-covering. Surface-covering degree on the test spot of ground-cutting slopes nine weeks after test construction showed more than 75% both executed by Coir net with Seed spray construction method and executed by furrow-digger with Seed spray and Straw mat-mulching measures. As a result of survey on appearing plants on the test spots, there dominates Eragrostis curvula both on ground-raised slopes and on ground-cutting slopes with other seeding plant life's lower breeding and there appear intruders, such as Setaria viridis Beauv, Digitaria sanguinalis Scop, and Chenopodium album var.centrorubrum Makino. As for water-borne excavation and soil's washing-away on the slopes, there happened less washing-away and water-borne excavation with good breeding of plant life on test spots executed both by Coir net with Seed spray construction method and by furrow-digger with Seed spray and Straw mat-mulching measures, but there happened much more soil's washing-away along with water-home excavation at the test spot executed by Seed spray with measures. After the research results of test construction sites are examined overall, it's presumed that furrow-digger with Seed spray and Straw mat-mulching measures [interval between lines is 40cm, 5cm in depth] will be preferred to prevent erosion and water-home excavation of slopes located within the construction sites.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.5
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• pp.628-636
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• 2018

Because large buoys are mainly made of steel, they are heavy and vulnerable to corrosion by sea water. This makes buoy installation and maintenance difficult. Moreover, vessel collision accidents with buoys and damage to vessels due to the material of buoys (e.g., steel) are reported every year. Recently, light buoys adopting eco-friendly and lightweight materials have come into the spotlight in order to solve the previously-mentioned problems. In Korea, a new lightweight buoy with a 7-Nautical Mile lantern adopting expanded polypropylene (EPP) and aluminum to create a buoyant body and tower structure, respectively, was developed in 2017. When these light buoys are operated in the ocean, the visibility and angle of light from the lantern installed on the light buoys changes, which may cause them to function improperly. Therefore, research on the performance of light buoys is needed since the weight distribution and motion characteristics of these new buoys differ from conventional models. In this study, stability estimation and motion analyses for newly-developed buoys under various environmental conditions considering a mooring line were carried out using ANSYS AQWA. Numerical simulations for the estimation of wind and current loads were performed using commercial CFD software, Siemens STAR-CCM+, to increase the accuracy of motion analysis. By comparing the estimated maximum significant motions of the light buoys, it was found that waves and currents were more influential in the motion of the buoys. And, the estimated motions of the buoys became larger as the sea state became worser, which might be the reason that the peak frequencies of the wave spectra got closer to those of the buoys.

• Korean journal of applied entomology
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• v.45 no.2 s.143
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• pp.201-209
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• 2006

Five strains of Korean entomopathogenic nematodes (EPN), steinernematids and heterorhabditids were evaluated and tried in laboratory, pot, and vegetable greenhouses for environmentally friendly control of diamondback moth (DBM), Plutella xyiostella, from 2002 to 2005. LC$_{50}$ values of five EPN strains against DBM were different depending on nematode strain and DBM instar. LC$_{50}$ value of Steinernema carpocapsae GSN1 (GSN1) was the lowest representing 2.6$\sim$3.9 infective juveniles (Ijs, 3rd stage) to 2nd to 4th instars of DBM. Pathogenicity of five effective strains against DBM was different depending on nematode strain, concentration, application times, and vegetable in pot. The most effective nematode was GSN1. Steinernema spp. was more effective than Heterorhabditis spp. against DBM. Two or three times of applications of EPN were effective regardless of nematode strain and concentration in pot. Efficacy of EPN was different depending on vegetable species. Efficacy was higher on Chinese cabbage, red mustard, and Ssamchoo than that on cabbage, kale, and leaf broccoli. Efficacy of GSN1, Steinernema GSNUS-10, Steinernema CSNUS-14, and Heterorhabditis GSNUH-1 was variable depending on nematode strain, concentration, application times, and vegetable in greenhouse experiments. GSN1 was the most effective and 100,000 infective juveniles per m$^2$(=$1\times10^9$ Ijs/ha) resulted in higher efficacy. Three times of application of nematodes led to higher control efficacy than one or two applications. Efficacy of nematodes was higher on Chinese cabbage than cabbage or kale in greenhouse.