• Membrane Journal
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• v.21 no.1
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• pp.46-54
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• 2011

In this study, combined effect of airflow rate, $TiO_2$ concentration, solution pH and $Ca^{+2}$ addition on HA (humic acid) fouling in submerged, photocatalytic hollow-fiber microfiltraiton was investigated systematically. Results showed that UV irradiation alone without $TiO_2$ nanoparticles could reduce HA fouling by 40% higher than the fouling obtained without UV irradiation. Compared to the HA fouling without UV irradiation and $TiO_2$ nanoparticles, the HA fouling reduction was about 25% higher only after the addition of $TiO_2$ nanoparticles. Both adsorptive and hydrophilic properties of $TiO_2$ nanoparticles for the HA can be involved in mitigating membrane fouling. It was also found that the aeration itself had lowest effect on fouling mitigation while the HA fouling was affected significantly by solution pH. Transient behavior of zeta potential at different solution pHs suggested that electrostatic interactions between HA and $TiO_2$ nanoparticles should improve photocatalytic efficiency on HA fouling. $TiO_2$ concentration was observed to be more important factor than airflow rate to reduce HA fouling, implying that surface reactivity on $TiO_2$ naoparticles should be important fouling mitigation mechanisms in submerged, photocatalyic microfiltraiton. This was further supported by investigating the effect of $Ca^{+2}$ addition on fouling mitigation. At higher pH (= 10), addition of $Ca^{+2}$ can play an important role in bridging between HA and $TiO_2$ nanoparticles and increasing surface reactivity on nanoparticles, thereby reducing membrane fouling.

• Journal of Microbiology and Biotechnology
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• v.18 no.10
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• pp.1621-1629
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• 2008

Harmful algal blooms (HABs), commonly called red tides, are caused by some toxic phytoplanktons, and have made massive economic losses as well as marine environmental disturbances. As an effective and environment-friendly strategy to control HAB outbreaks, biological methods using marine bacteria capable of killing the harmful algae or algicidal extracellular compounds from them have been given attention. A new member of the $\gamma$-Proteobacteria, Hahella chejuensis KCTC 2396, was originally isolated from the Korean seashore for its ability to secrete industrially useful polysaccharides, and was characterized to produce a red pigment. This pigment later was identified as an alkaloid compound, prodigiosin. During the past several decades, prodigiosin has been extensively studied for its medical potential as immunosuppressants and antitumor agents, owing to its antibiotic and cytotoxic activities. The lytic activity of this marvelous molecule against Cochlodinium polykrikoides cells at very low concentrations ($\sim$l ppb) was serendipitously detected, making H. chejuensis a strong candidate among the biological agents for HAB control. This review provides a brief overview of algicidal marine bacteria and their products, and describes in detail the algicidal characteristics, biosynthetic process, and genetic regulation of prodigiosin as a model among the compounds active against red-tide organisms from the biochemical and genetic viewpoints.

• Journal of the Korean Society of Marine Environment & Safety
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• v.19 no.2
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• pp.145-154
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• 2013

HNS, including crude oil and products, shipments have increased. The risk analysis of HNS has assumed the importance, especially in maritime transportation area. There are various forms and kinds of HNS and the consequences of an accident are serious. In order to provide practical measures for preventing accidents, this study analyses the potential risks of HNS on maritime transportation accidents at domestic sea by using Event Tree Analysis. This study carries out risk assessment with F-N curve and risk matrix focusing on liquid cargo carriers (Oil and Products Tanker, Chemical Tanker, LPG/LNG Tanker, etc.). Explosion and sinking, suffocation indicate high consequence when on collision represent high probability. Improving human errors should be the main factor to mitigate risk on human lives.

• Land and Housing Review
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• v.5 no.2
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• pp.107-114
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• 2014

Passive energy dissipation systems for seismic applications have been under development for a number of years with a rapid increase in implementations starting in the mid-1990s in many countries. A metallic hysteretic damper has most commonly been used for seismic protection of structures in domestic area because they present high energy-dissipation potential at relatively low cost and easy to install and maintain. This paper presents an analytical case study of the effectiveness of isotropic hysteretic metallic damper(IHMD) called Kagome as a passive dissipative device in reducing structural response during seismic excitation. An eighteen-story RC framed apartment building is studied with and without IHMD. Results demonstrate the feasibility of these techniques for seismic mitigation. The inclusion of supplemental passive energy dissipation devices in the form of IHMD proved to be a very effective method for significantly reducing the seismic response of the building investigated.

• Korean Journal of Soil Science and Fertilizer
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• v.46 no.5
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• pp.391-398
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• 2013

Soil organic carbon (SOC) has the potential to promote the soil quality for sustainability and mitigation of global warming. There is little information on organic carbon composition despite of having resistance of carbon degradation in soil. In this study, to understand the effect of volcanic ash on organic carbon composition and quantity in soil, we investigated characteristics of volcanic soil and compared organic carbon composition of soil and humic extract by using $^{13}C$-CPMAS-NMR spectra under soil profiles of Namweon series in Jeju. SOC contents of inner soil profiles were 134.8, 101.3, and 27.4 g C $kg^{-1}$ at the layer of depth 10-20, 70-80 and 90-100 cm, respectively. These layers were significantly different to soil pH, oxalate Al contents, and soil moisture contents. Alkyl C/O-alkyl C ratio in soil was higher than that of humic extracts, which was decreased below soil depth. Aromaticity of soil and humic extract was ranged from 29-38 and 24-32%, which was highest at the humic extract of 70-80 cm in soil depth. These results indicate that the changes of SOC in volcanic ash soil resulted from alteration of organic composition by pyrolysis and stability of organic carbon by allophane in volcanic ash soil.

• Journal of the Korean Wood Science and Technology
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• v.46 no.2
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• pp.202-210
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• 2018

This study was carried out to quantify degree of contribution of harvested wood product (HWP) on mitigation of climate change by valuation of public benefits, environmentally and economically. The potential carbon dioxide emission reduction of HWP was estimated by accounting carbon storage effect and substitution effect. Based on 2014 statistics of Korea Forest Service, domestic HWPs were sorted by two categories, such as wood products produced domestically from domestic and imported roundwood. The wood products were divided into seven items; sawnwood, plywood, particle board, fiberboard (MDF), paper (including pulp), biomass (wood pellet) and other products. The carbon stock of wood products and substitution effects during manufacturing process was evaluated by items. Based on the relevant carbon emission factor and life cycle analysis, the amount of carbon dioxide emission per unit volume on HWP was quantified. The amounts of carbon stock of HWP produced from domestic and from imported roundwood were 3.8 million $tCO_{2eq}$., and 2.6 million $tCO_{2eq}$., respectively. Also, each reduction of carbon emission by substitution effect of HWP produced from domestic and imported roundwood was 3.1 million $tCO_{2eq}$. and 2.1 million $tCO_{2eq}$., respectively. The results of this study, the amount of carbon emission reduction of HWP, can be effectively used as a basic data for promotion of wood utilization to revise and establish new wood utilization promotion policy such as 'forest carbon offset scheme', and 'carbon storage labeling system of HWP'.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.17 no.4
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• pp.17-27
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• 2014

Wind power which is one of renewable energies is higher economical efficiency and technical maturity than other renewable energies. Recently, the government of ROK announced to increase the proportion of renewable energy through the National Energy Plan. Also, industry required to deregulate for large-scale wind power as Renewable Portfolio Standard (RPS) is introduced. Wind power whereas the eco-friendly energy, is a serious level of damage of the natural environment and topography when the wind power is located. Therefore, the study selected the indicators required for site selection of wind power and proposed the feasible area for wind power based on wind resource map. We selected the 15 indicators including 12 legal protected area, Ecology and Nature Map, rarity, and connectivity (National Ecological Network). After site selection, we should be considered slope and altitude at the stage of design for wind farm to mitigate the environmental impact. Results of analysis showed that 22.3% of wind resource map is available to locate wind power in real. Through the field survey we had verified the accuracy of the results was significantly correct.

• Journal of Animal Science and Technology
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• v.53 no.3
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• pp.261-268
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• 2011

The increasing demand of the crops (soybean and corn) for biofuel production has increased the focus of the animal nutritionists to look for alternative feeds, which are economic and environmental friendly. To identify microalgae as suitable candidate as an alternative feed, growth response of Chlorella vulgaris was studied under varying concentrations of carbon dioxide (0.07, 1.4, 3.0 and 5.0%) and photon densities (39.19, 72.97, 105.41, 116.22, 135.14, $175.68\;{\mu}mol/m^2/s$) by employing a photo-bioreactor. Swine wastewater was also investigated as nutritional source to economize the biomass production. Results showed that the higher biomass production was found to be at 3.0% $CO_2$ compared to other $CO_2$ concentrations. However, no difference in biomass production was found at $105.41\;{\mu}mol/m^2/s$ and above photon densities with 12 h of photoperiodicity. It was observed that C. vulgaris could easily grow in 200 times diluted swine wastewater and growth was found to be similar with that of artificial medium. Provided the conducive conditions for optimal growth, it has also the potentiality of depleting ammonia nitrogen ($NH_4$-N) and orthophosphate ($PO_4^{3-}$-P) completely from the wastewater after 3~4 days of cultivation. Thus, growing C. vulgaris would not only solve the problem of animal feed, but also help in biological $CO_2$ mitigation and wastewater treatment.

• Journal of Korea Water Resources Association
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• v.40 no.4
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• pp.313-324
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• 2007

An irregular cell-based numerical model was developed to analyze underground space flooding. In this model, the flow characteristics in underground space were computed by link-node system. Also, the model can simulate the underground flood flow related to the influence of stairs and wall-structures. Empirical discharge formula were introduced to analyze weir-type flow for shopping mall, and channel-type flow for subway railroad respectively. The simulated results matched in reasonable range compared with the observed depth. The dual-drainage inundation analysis model and the underground space flood analysis model were integrated using visual basic application of ArcGIS system. The developed model can help the decision support system of flood control authority for redesigning and constructing flood prevention structures and making the potential inundation zone, and establishing flood-mitigation measures.

• Journal of the Korean Society of Safety
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• v.32 no.6
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• pp.54-60
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• 2017

A railway rail will be corroded by the repetitive sea wind and fog in the splash and tidal zone such as Youngjong grand bridge. And these rusts of rail could be increased by increasing service period, and it frequently occurred the safety accidents or disorders in electrical problem. In this study, the sacrificial anode cathodic protection method was proposed as a measures for reducing the corrosion of the railway rails in the oceanic climate conditions. As the results of immersion test using the salt water during four months, the sacrificial anode cathodic protection method using the aluminum anode(Al-anode) was evaluated that a distinct effect on corrosion reduction in the rails. Therefore the sacrificial anode cathodic protection method was experimentally proven that a disorders in aspects electric and signal of railway operation condition such as direct fixation track system in Youngjong grand bridge could be prevented by reducing rust falling from the rail. In addition, the installation conditions of the anodes directly affect the transmission range of corrosion potential, the sectional loss of anode, and the corrosion reduction effect. Therefore, to expect the corrosion reduction effect of rails under the oceanic climate conditions for railway track, it was important to adopted the appropriate spacing of anode installation by considering the actual field conditions.