• Journal of the Korean Society for Marine Environment & Energy
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• v.5 no.1
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• pp.51-67
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• 2002

In order to understand behaviors of heavy metals around the artificial Lake Shihwa in the vicinity of Kyunggi Bay in Korea in relation with huge environmental changes due to construction of huge artificial lake, water samples were collected from Lake Shihwa and its tributaries from 1996 to 1998 and analyzed. Due to extreme pollutant discharge from various kinds of anthropogenic sources such as the Banweol and Shihwa Industrial Complexes and cities, the Shihwa and its tributaries have been polluted in waters with various heavy metals. The enrichment factors of particulate heavy metals in water of streams and storm sewers were very high. All of the heavy metals observed in the waters showed relatively high temporal and spatial variations. In surface waters of the lake during the desalination after the dike establishment, spatial distributions of heavy metal concentrations were mainly controlled by various biogeochemical factors as well as input of industrial and municipal wastewaters, while, physical mixing was minor factor Pb and Co showed a strong affinity to particle phase, however the affinity to dissolved phase was dominated in Ni, Cu and Cd. Water quality of the artificial Lake Shihwa has been deteriorated by direct discharge of untreated wastewater and heavy metals have been accumulated in the lake system. Therefore, luther environmental improvement plan should be programmed subsequently.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.11 no.3
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• pp.193-198
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• 2013

In general, boron recovery of 40-90% could be achieved by Reverse Osmosis (RO) membranes in neutral pH condition. As an emerging technology, Forward Osmosis (FO) membrane has attracted growing interest in wastewater treatment and desalination. The objective of this study is to evaluate the possibility of the boron removal in radioactive liquid waste by FO. In this study, the performance of FO was investigated to remove boron in the simulated liquid waste as the factors such as pH, osmotic pressure, ionic strength of solution, etc. The pH of feed solution is a major operating parameter which strongly influences to the permeation of boron and more than 80% of boron content can be separated when conducted at pH values less than 7. The water flux is not influenced but the boron flux and permeation rate tends to decrease in the low salt concentration of 1,000 mg/L. The boron flux increases linearly, but the permeation ratio of reducing boron is nearly constant even with changes in the draw solution concentration.

• Korean Journal of Environmental Agriculture
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• v.37 no.3
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• pp.197-206
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• 2018

BACKGROUND: The present study aimed to examine the crops capable of growing and adapting to the external environment and various stresses of reclaimed agriculture land for the development of high value-added agricultural utilization technology based on reclaimed land through standardization and empirical study of cultivation environment for cultivating crops. METHODS AND RESULTS: Two crops namely turnips and beets were selected for the salt tolerance test of soil environmental conditions on reclaimed land. Turnip and beet seedlings were planted on the soil collected at the 'Seokmun' reclaimed land. There are five treatments such as non-treatment, 1.0, 2.0 (control), 4.0 and $8.0dS{\cdot}m^{-1}$ of EC. The contents of betacyanin in beet roots was highest in control and decreased with increasing salt concentration. The GSL contents in the turnip roots waswere highest at EC 2.0 and decreased with increasing salt concentration, whereas those in turnip leaves waswere high both in the non-treated control and atthe EC 1.0-treatment. But, tThere was, however, no statistical differences among the treatments. CONCLUSION: The degree of salt tolerance of crops was examined, and the limit EC iswas expected to be $3.0{\sim}4.0dS{\cdot}m^{-1}$ as reported to date. If the soil improvement is performed and irrigation systems are used in the actual reclaimed land, the EC of supplied irrigation will be low, and desalination effecttreatment by the lower EC of the supplied irrigation on the soil will lead to more favorable soil condition of the rhizosphere and cultivation environment offor the crops than those in the port experiment. Therefore, monitoring the salinity, water content and ground water level will enable prediction of the rhizosphere environment, and setting up irrigation management and supplying irrigation will lead to crop cultivation results that are close to normal.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.3
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• pp.179-184
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• 2019

In many countries, such as developing countries where electricity is scarce, small wind turbines in the form of Off Grid are an effective solution to solve power supply problems. In some countries, the expansion of power systems and the decline of electricity-intensive areas have led to the use of small wind power in urban road lighting, mobile communications base stations, aquaculture and seawater desalination. With this change, the size of the small wind power industry is expected to have greater potential than large-scale wind power. In the case of small wind power generators, the generator is controlled at a variable speed, and the voltage and current generated by the generator have many harmonic components. To solve this problem, the AC to DC converter to be studied in this paper is a three-phase step-up type converter with a single switch. The inductor current is controlled in discontinuous mode, and has a characteristic of having a unit power factor by eliminating the harmonic of the input current. The proposed converter is composed of LCL filter and three phase rectification boost converter at the input stage and a single phase full bridge for grid connection. It is a control system with energy storage system(ESS) that the system stabilization can be pursued against the electric power.

• Korean Chemical Engineering Research
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• v.57 no.3
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• pp.378-386
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• 2019

In the present paper we report the calculation results of operation energy consumption for dissolved ions concentration technologies using vacuum evaporation (VE) and hydrate formation. Calculations were conducted assuming the tenfold concentration of saline water (0.35 wt% NaCl solution) of 1 mol/s at room temperature and atmospheric pressure employing vacuum evaporation at $69^{\circ}C$ and 30 kPa and hydrate-based concentration using $CH_4$, $CO_2$ and $SF_6$ as guest molecules. Operation energy consumption of VE-based concentration resulted in 47 kJ/mol, whereas those of hydrate-based concentration were 43, 32, and 28 kJ/mol for $CH_4$, $CO_2$ and $SF_6$ hydrates, respectively. We observe that hydrate-based concentration can a competitive option for dissolved ions recovery from energy consumption standpoint. However, the selection of guest gas is very critical, since it accordingly determines the hydration number, the hydrate formation energy, gas compression energy, etc. The selection of guest gas, separation of concentrated brine and water phases, and the enhancement of hydrate formation rate are the key factors for the commercialization of hydrated-based technology for concentrating dissolved ions.

• Membrane Journal
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• v.28 no.6
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• pp.379-387
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• 2018

This study was conducted to improve the membrane characteristics and performance by increasing hydrophilicity by adding additives to the ultrafiltration polysulfone (PSf) hollow fiber membrane. The mixed matrix membranes (MMMs) were prepared by dispersing 15 nm of fumed silica (FS) in the spinning solution at 0.1, 0.3 and 0.5 wt%. SEM analysis was carried out to confirm the cross-section and surface condition. It was confirmed that mean pore radius of the hollow fiber increased by 4 nm as FS was added. In addition, contact angle measurement was carried out for the hydrophilicity analysis of hollow fiber membranes, and it was confirmed that the hydrophilicity of MMMs were increased by adding of FS. In the case of water permeability, the membrane including FS showed 91~96 LMH and showed 5~11% more increase than PSf membrane. In the antifouling performance test, relative flux reduction ratios of FS mixed hollow fiber membranes were lower than that of PSf membranes, and it was confirmed that increase of hydrophilicity hinders adsorption of hydrophobic BSA on the membrane surface.

• Journal of Appropriate Technology
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• v.7 no.1
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• pp.93-101
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• 2021

Scientists and engineers without borders (SEWB) was established on 2009 as the NGO having specialist groups to support the underprivileged in developing countries living in the isolated area and having water and sanitation problems. After the SDGs were suggested by the UN on 2016, activities are globally conducted by the nation, NGO and etc. to improve health and education of the underprivileged in developing countries. SEWB also have been conducted the projects in Korea and developing countries to reduce the gap of the infrastructure between the developed and developing countries and to help sustainable development in the developing countries by providing appropriate technology. In Korea, SEWB have been held international conference on appropriate technology (ICAT), lectures, and competitions for specialists and students. In developing countries including Cambodia and other 5 countries, SEWB have been provided water packages funded by iCOOP KOREA and volunteer opportunities. Since 2019, 'SEWB sustainable village development project' have been conducted in Bot Veng village, Cambodia to improve infrastructures on water, electricity, transportation, and agriculture by using desalination system, Solar Cow system, strengthened wooden bridge, and poultry farm, respectively. The developed solution for developing countries from SEWB could contribute to eliminate the water shortage and poverty.

• Journal of Conservation Science
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• v.37 no.6
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• pp.821-830
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• 2021

The weapons excavated from the de-militarized zones (DMZ) of Korea are vulnerable to corrosion due to the immediate and drastic environmental change. Especially, the chloride ions (Cl^-) in iron weapons cause active corrosion and require removal. In this study, conservation treatment and de-salination was performed for the discovered weapons from excavation sites of soldiers killed in action during the Korean War. Furthermore, an attempt was made to prepare the most stable plan for conservation treatment through the comparative study of soaking weapons in distilled water without chemicals and in a solution of sodium (SSC) at different temperatures. In the preliminarily experiments, the comparison of the eluted Cl^- ions according to different conditions of de-salination showed that the highest number of ions were detected from the de-salination with SSC at a temperature of 100℃, and its duration was much smaller, i.e., 1~2 weeks. Accordingly, for the parts from the guns and rifles amongst other objects, a six-time de-salination was conducted in the SSC solution for 8 hours at 100℃ and subsequently, for 16 hours at room temperature during which the distilled water and SSC were exchanged every week. However, in the case of a loaded rifle, the de-salination was not conducted, considering the risk that the high temperature and pressure by impregnation in vacuum could cause an explosion

• KSCE Journal of Civil and Environmental Engineering Research
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• v.4 no.4
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• pp.113-125
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• 1984

Water supply has been mainly dependent on the construction of the dams in Korea. It is difficult, however, to continue to construct dams for many reasons, such as the decrease of construction sites, the increase of construction costs, the compensation of residents in flooded areas, and the environmental effects. Water demands have increased and are expected to continue increasing due to the concentration of people in the cities, the rise of the living standard, and rapid industrial growth. It is acutely important to find countermeasures such as development of ground water, desalination, and recycling of waste water to cope with increasing water demands. Recycling waste water includes all means of supplying non-potable water for their respective usages with proper water quality which is not the same quality as potable water. The usages of the recycled water include toilet flushing, air conditioning, car washing, yard watering, road cleaning, park sprinkling, and fire fighting, etc. Raw water for recycling is obtained from drainage water from buildings, toilets, and cooling towers, treated waste water, polluted rivers, ground water, reinfall, etc. The water quantity must be considered as well as its quality in selecting raw water for the recycling. The types of recycling may be classified roughly into closed recycle systems and open recycle systems, which can be further subdivided into individual recycle systems, regional recycle systems and large scale recycle system. The treatment methods of wastewater combine biochemical and physiochemical methods. The former includes activated sludge treatment, bio-disc treatment, and contact aeration treatment, and the latter contains sedimentation, sand filtration, activated carbon adsorption, ozone treatment, chlorination, and membrane filter. The recycling patterns in other countries were investigated and the effects of the recycling were divided into direct and indirect effects. The problems of water reuse in recycle patterns were also studied. The problems include technological, sanitary, and operational problems as well as cost and legislative ones. The duties of installation and administrative organization, structural standards for reuse of water, maintenance and financial disposal were also studied.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.1
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• pp.529-536
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• 2011

In this study, we confirmed that the SWRO(Sea Water Reverse Osmosis) production water has more hard corrosiveness than the tap water by fundamental experiment. According to the result, the target of this study was aimed at developing maintenance and anti-corrosion method. In the early stages of the research, batch tests using mild steel coupons and electrochemical experiments were applied to compare the corrosiveness between SWRO production water and the tap water. After then, two corrosion control methods for SWRO production water were applied. Liquid lime($Ca(OH)_2$) and Carbon Dioxide($CO_2$) were inserted and compared with the combination of liquid lime with phosphate corrosion inhibitor and carbon dioxide. The water qualities were evaluated through LSI(Langelier Saturation Index) and proper injection ratio was deduced by the result. Since then, simulated loop system test were performed to evaluate anti-corrosion effect depending on corrosion inhibitors. Subsequently, carbon steel pipes equipped at the loop system were detached for SEM, EDX and XRD analysis to acquire quantitative and qualitative data of the major corrosion products inside the pipes. In conclusion, the controled groups with anti-corrosion techniques applied were effective by appearing 97.4% and 90.9% of improvements in both case of liquid lime and the liquid lime with a phosphate corrosion Inhibitor. furthermore, major components of scale were iron oxides, on the other hand, protective effect of film formation by calcium carbonate($CaCO_3$) could be confirmed.