• Proceedings of the Microbiological Society of Korea Conference
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• 2008.05a
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• pp.42-44
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• 2008

Bacterial biofilms are analogous to multi-cellular organisms or to clonal communities of higher organisms. In this respect, it can be demonstrated that biofilms display the type of genetic variation associated with macroorganisms. The formation of genetic variants from biofilms is the result of internally produced and regulated signals and the appearance of these variants coincides with dispersal from the biofilm. Moreover, the generation of such variation, has similar outcomes for the bacterial community, where diversification of phenotypic traits ensures that the bacterial community optimizes its chances of success when dispersing or surviving when challenged with environmental stress. These observations increase the complexity with which we view bacteria and also suggest that microbial systems can serve as models for the testing of eukaryotic ecological theories.

• Journal of The Korean Society of Agricultural Engineers
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• v.62 no.1
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• pp.1-16
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• 2020

The APEX model has been developed for assessing agricultural management efforts and their effects on soil and water at the field scale as well as more complex multi-subarea landscapes, whole farms, and watersheds. Recently, a key component of APEX application, named APEX-Paddy, has been modified for simulating water quality by considering paddy rice management practices. In this study, the performance of the APEX-Paddy model was evaluated using field data at Iksan experimental paddy sites in Korea. The discharge and pollutant load data during 2013 and 2014 were used to both manually and automatically calibrate the model. The APEX auto-calibration tool (APEX-CUTE 4.1) was used for model calibration and sensitivity analysis. Results indicate that APEX-Paddy reasonably performs in predicting runoff discharge rate and nitrogen yield. However, sediment and phosphorus yield is not correctly predicted due to the limitation of model schemes. With APEX-Paddy, the performance in reproducing the discharge and nitrogen yield is found to be a satisfactory level after manual calibration. The manually calibrated model performed better than the automatically calibrated model in nearly all comparisons. For runoff, manual calibration reduced PBIAS while R² and NSE values of the automatically calibrated model were the same as the manual calibration. For T-N, NSE and PBIAS were reduced when using manual calibration, whereas R² value was the same as manual calibration. The limitation of the APEX-Paddy model for predicting sediment, as well as the phosphorous yield, was discussed in this study.

• Korean Journal of Environmental Agriculture
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• v.31 no.2
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• pp.129-136
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• 2012

BACKGROUND: The changes in the climatic conditions have brought potentially significant new challenges, most critical are likely to be its impact on local livelihoods, agriculture, biodiversity and environments. Water induced disasters such as landslides, floods, erratic rain etc., are very common in developing countries which lead to changes in biological, geophysical and socioeconomic elements. The extent of damages caused by natural disasters is more sever in least developing countries. However, disasters affect women and men differently. In most of the cases women have to carry more burden as compared to their male counterpart during the period of disasters. METHODS AND RESULTS: This study examines the impact of disasters on the local livelihood especially agriculture and income generating activities of women in three districts of Nepal. The study uses the primary data collected following an exploratory approach, based on an intensive field study. The general findings of the study revealed that women had to experience hard time as compared to their male counterpart both during and after the disaster happen. Women are responsible for caring their children, collecting firewood, fetching water, collecting grass for livestock and performing household chores. Whereas, men are mainly involved in out-migration and remained out-side home most of the time. After the disaster occurred, most of the women had to struggle to support their lives as well as had to work longer hours than men during reconstruction period. Nepal follows patriarchal system and men can afford more leisure time as compared to women. During the disaster period, some of the households lost their agricultural lands, livestock and other properties. These losses created some additional workload to women respondent, however at the same time; they learn to build confidence, self-respect, self-esteem, and self-dependency.Although Nepal is predominantly agriculture, majority of the farmers are at subsistence level. In addition, men and women have different roles which differ with the variation in agro-production systems. Moreover women are extensively involved in agricultural activities though their importances were not recognized. Denial of land ownership and denial of access to resources as well as migration of male counterparts are some of the major reasons for affecting the agricultural environments for women in Nepal. CONCLUSION: The shelter reconstruction program has definitely brought positive change in women's access to decision making. The gradual increase in number of women respondent in access to decision making in different areas is a positive change and this has also provided them with a unique opportunity to change their gendered status in society.Furthermore, the exodus out-flow of male counterparts accelerated the additional burden and workload on women.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.14 no.6
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• pp.97-109
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• 2011

Korea introduced the cooperation charge on conservation of ecosystem for minimizing damage of ecosystem due to development projects and their effects and for preparing resources for natural environment conservation projects. Advanced countries have made efforts by expanding investment in natural environment conservation and restoring projects to promote prevention of global warming and improvement of biological diversity, are establishing nationwide strategies and plans. To examine the reality of projects by returns of the cooperation charge on conservation of ecosystem, microsite projects in schools and public facilities take the largest share while their project budgets are only about 100~300 KRW, relatively small, which might be attributable to budget restrictions in accordance with the calculating method of levying cooperation charge on conservation of ecosystem and problems of project proceeding in the system of returning fund for projects in general. The conclusion which this study suggests on invigoration of cooperation charge on conservation of ecosystem and its operation are as followings. First, although the cooperation charge on conservation of ecosystem has been introduced in 2001, the amount of imposition per unit area remains unchanged. It is desirable to increase the amount into $1,400KRW/m^2$ as of August, 2011 as the price index has been continuously rising for the past 10 years and the upward adjustment of imposition per unit area should be notified by the decree of the Ministry of Environment every January. Second, the ceiling amount of the cooperation charge on conservation of ecosystem should be abolished. Now the ceiling amount is defined as 1 billion KRW but it was found that there was not any ceiling amount specified according to the comparative analysis of similar systems with the Korean environmental improvement fund. The ceiling should be abolished so that medium level businesses are carried out and ecosystem recovering projects in the true sense of the word can be made smoothly. Third, weight should be introduced in calculating amounts in accordance with ecologic and economic values. Harmony between development and environment can be achieved by applying differentiated weights of constant regional coefficient by use zone and ecologic and economic values. Continuous efforts of improving cooperation charge on conservation of ecosystem should be made more than anything else so that projects by returns of cooperation charge on conservation of ecosystem get effectiveness.

• Applied Chemistry for Engineering
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• v.27 no.5
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• pp.532-536
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• 2016

In this study, single-stage continuous anaerobic reactors to treat sewage sludge were operated under different temperature (55 and $35^{\circ}C$; $R_{TAD}$ and $R_{MAD}$) to evaluate the reactor stability and performance of the thermophilic and mesophilic anaerobic digestion. During the overall digestion, both anaerobic reactors maintained quite stable and constant pH and total alkalinity (TA) values in the range of 6.5-8.0 and 3-4 g $CaCO_3/L$, respectively. After the start-up period, $R_{TAD}$ showed 10% higher VS removal efficiency than that of $R_{MAD}$ ($R_{TAD}$; 43.3%; $R_{MAD}$ : 33.6%). Although organic acids such as acetic and propionic acid were detected in both anaerobic reactors at the start-up period, all organic acids in $R_{TAD}$ and $R_{MAD}$ were consumed at the steady state condition. Also $R_{TAD}$ showed 31.4 % higher methane production rate (MPR) than that of $R_{MAD}$ at the steady state condition ($R_{TAD}$; 243 mL $CH_4/L/d$; $R_{MAD}$ : 185 mL $CH_4/L/d$). Meanwhile, the experimental results indicated similar methane yield between $R_{TAD}$ and $R_{MAD}$.

• Applied Chemistry for Engineering
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• v.28 no.5
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• pp.581-586
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• 2017

In this study, in order to find the feasibility of thermophilic biological pre-treatment for the co-digestion of food wastewater and sewage sludge, digestion efficiency of the combined thermophilic aerobic and mesophilic anaerobic process and its effect on methane production were investigated. Also, a lab-scale co-digestion process was operated to observe parameter changes according to the increase of organic loading rates using different dilution ratios of distilled water and food wastewater (1/3 [Run I], 2/3 [Run II] in addition to using the raw food wastewater [Run III]). The results indicated that co-digestion process maintained quite stable and constant pH during entire experiments. With regard to VS removal, the higher removal was observed in the combined process and the removal efficiency was 52.24% (Run I), 66.59% (Run II) and 72.53 (Run III), respectively. In addition, the combined process showed about an 1.6-fold improved methane production rate and significantly higher methane yield than that of using single anaerobic digestion process.

• KSBB Journal
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• v.20 no.3
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• pp.210-214
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• 2005

The characteristics of sesame oil containing one of natural antioxidant, ' $\gamma$-tocopherol', were studied with the supercritical $CO_2$ extraction. Although $\gamma$-tocopherol has a lower vitamin E value in biological systems than $\alpha$-tocopherol, it is a more potent antioxidant with in oils. For the research of various factors influence to the $\gamma$-tocopherol contents increment, we have checked roasting time and temperature, as well as pressure, temperature and flow rate of supercritical fluid. As a result, we found that the $\gamma$-tocopherol content was maintained constant under the condition of roasting temperature over $200^{\circ}C$. With the longer roasting time, $\gamma$-tocopherol content was increased. Except 250 bar, the $\gamma$-tocopherol content was maintained constant under the condition of the various pressure of supercritical fluid. But $\gamma$-tocopherol content was increased with lower flow rate of supercritical fluid from 1 $m{\ell}$/L to 3 $m{\ell}$/L. When the extraction performance with the supercritical fluid was compared to the conventional compressed extraction, $\gamma$-tocopherol content was increased up to 1.6 times.

• Korean Journal of Environment and Ecology
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• v.31 no.5
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• pp.461-471
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• 2017

Population genetic studies of 10 groups of Iksookimia pacifica were conducted to investigate the genetic diversity and population genetic structure across its known range in South Korea. Population DNA sequences of one mitochondrial gene (mtCOI) and three nuclear genes (IRBP, EGR2B, RAG1) were examined in samples collected from ten streams that flow into the East Sea. Both mitochondrial and nuclear sequences exhibited significant differentiation among populations except a few cases. The Bayesian analysis of the multi-locus genotypes inferred from the DNA sequences of nuclear genes clustered the individual fish largely into two geographical groups: a northern group (from Baebong stream to Cheonjin stream) and a southern group (Yangyangnamdae stream to Gangneungnamdae stream). Given that the streams flowing into the East Sea are geographically isolated water systems, such separation of genotypes can be interpreted by the geographical separation of common ancestors into north and south that had colonized South Korea. Since the initial geographical separation of the ancestral population by north and south, the ancestral groups seem to have experienced further differentiation into the current genetic clusters through the physical isolation of streams by the East Sea in each region. It is notable that many individuals in the Jasan stream formed a genetic cluster with those of Yangyangnamdae and Gangneungnamdae streams which are distant from each other. In addition, mitochondrial gene showed low genetic differentiation between some neighboring populations and very low level of genetic diversity in several populations. The present population genetic study will provide valuable information for the conservation and management of the Korean endemic fish species, I. paicifica.

• Clean Technology
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• v.13 no.1 s.36
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• pp.1-15
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• 2007

Biological treatment is a relatively recent air pollution control technology in which off-gases containing biodegradable odors and volatile organic compounds(VOCs) are vented through microbes. It is a promising alternative to conventional air pollution control methods. Bioreactors for air pollution control have found most of their success in the treatment of dilute and high flow waste air streams containing VOCs and odor compounds. They offer several advantages over traditional technologies such as incineration or adsorption. These include lower treatment costs, absence of formation of secondary pollutants, no spent chemicals, low energy demand and low temperature treatment. The three most widely used technologies are described, namely biofiltration, biotrickling filtration, bioscrubbing. The most widely used bioreactor for air pollution control is biofilter, but it has several limitations. In the past years major progress has been accomplished in the development of vapor phase bioreaction systems, for solving problems of biofilter. Biotrickling filters are more complex than biofilters, but are usually more effective, especially for the treatment of compounds which are difficult to degrade or compounds that generate acidic by-products. This, paper reviews fundamental and theoretical/practical aspect of air pollution control in biofilter, biotrickling filter and bioscrubber, focusing more extensively on biotrickling filtration. Special emphasis is given to the operating parameters and the factors influencing performance for air pollution control, and cost estimation in biotreatment technologies.

• Clean Technology
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• v.19 no.4
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• pp.355-369
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• 2013

Economic feasibility is one of the most important factors in energy production from regenerative biomass. From the aspect, biogas from anaerobic digestion of wastewater sludge is regarded as the most economical because of its cheap substrate and additional income from the disposal of waste sludge. Sludge hydrolysis has been regarded as the rate limiting step of anaerobic digestion and many sludge pre-treatment technologies have been developed to accelerate anaerobic sludge digestion for enhanced biogas production. Various sludge pre-treatment technologies including biological, thermo hydrolysis, ultrasonic, and mechanical methods have been applied to full-scale systems. Sludge pre-treatment increased the efficiency of anaerobic digestion by enhancing hydrolysis, reducing residual soilds, and increasing biogas production. This paper introduces the characteristics of various sludge pre-treatment technologies and the energy balance and economic feasibility of each technology were compared to prepare a guideline for the selection of feasible pre-treatment technology. It was estimated that thermophilic digestion and thermal hydrolysis were most economical technology followed by Cell rupture$^{TM}$, OpenCEL$^{TM}$, MicroSludge$^{TM}$, and ultrasound. The cost for waste sludge disposal shares the biggest portion in the economic analysis, therefore, water content of the waste sludge was the most important factor to be controlled.