• Transactions of the Korean Society of Mechanical Engineers A
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• v.22 no.1
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• pp.227-237
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• 1998

In case the systems have radioactivity, toxic liquid or expensive fluid, and have to be performed repair work at one point of the system pipe, the formation of an internal ice plug by the removal of heat from the pipe is often consideredas a useful method. In this procedure, an annular jacket is placed around the pipe, and the jacket is then filled with liquid Nitrogen(-196.deg. C). Thermal analysis by the finite element method based on the laboratory experiments has been constructed. The result of the finite element analysis on the experimental model shows to be reasonable, and thus the finite element analysis for different pipe size, material and thickness has been performed to see if the ice plugging procedure in various applications can be safely performed without possibility of damage to the pipe. It has been confirmed that in carbon steel pipes the maximum stress is found around the boundary of the freezing jacket, and the stress increases as pipe thickness increases, but the maximum stress shows no consistency along the increment of the pipe diameter. The maximum stresses appear lower than yield stress in carbon steel. It has been also shown that in stainless steel pipes the maximum stresses are also found around the boundary of the freezing jacket, but almost the same value in spite of different pipe size an thickness, and the maximum stresses show slightly higher than the yield stress of the stainless steel.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.222-222
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• 2011

Plastic product is increasing by the growth of its demand and most of refused plastics are incinerated or reclaimed. However, the refused plastic is not easily decomposed and has the environmental problem with its various toxic gas in case of incineration. Therefore, many countries such as USA, Japan, Germany and other developed industrial countries as well as Korea are interested in studying the recyclable resource of refused plastic. The macromolecular waste pyrolysis has the advantage of collecting of raw materials in high price and can at least get fuel gas or oil with high heat capacity. It also discharges low waste gas and low toxic gas including SOx, NOx and HCl heavy metals. However, pyrolyzed oil includes enough excess unsaturated hydrocarbons to form tar, which can cause the nozzle of engines to plug when pyrolyzed oil is used as fuel. Activated carbon was proven to have prominent adsorption capability among the other adsorbents that were mainly composed of carbon. This study examined the possibility of application in activated charcoal of its solid formation by analysing the feature of pyrolysis which is one of the chemical recycling methods and getting chemical analysis of the product and activated energy. Analyze the element of the oil produced by pyrolysis using GC-MS. The experiment of tar adsorption using fly-ash showed that fly-ash improved the optical intensity of pyrolyzed oil and decreased oxygen compounds in the pyrolyzed oil.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.59 no.4
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• pp.532-538
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• 2014

Arsenic (As) is nonessential element toxic to plants. In Korea little is not only known about the extent of actual anthropogenic sources and inputs of arsenic to the agricultural land which plays a active role as a sink, but also systematic research on arsenic as an toxic element entering the food chain via the soil-plant pathway has not been investigated in the fields and greenhouses besides in few places of abandoned mining sites. Therefore, it is important to focus on the effect of As-contaminated soils on As uptake and biomass production of lettuce plants. In this study, As concentrations in the soil and accumulation of As in lettuce transferred by As uptake from soils were investigated. To do this, soil which was mixed with various rates of arsenopyrite gravels containing arsenic from 0 to 100% was packed into a round plastic pot. Then, 10 days old vegetable crops of chinese cabbage and lettuce after germination were transplanted into a pot. Growth of lettuce was observed for four weeks with one week interval. All experiments were done by triplicate. The results showed that the growth rates for number of leaves, width and length of the crop plants were retarded with increasing amount of gravel mixed due to increasing bioavailable amount of arsenate with increasing rate of gravel in soils. With these results, we conclude that the bioavailable amount of arsenate can influence the growth of lettuce.

• Membrane Journal
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• v.17 no.2
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• pp.99-111
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• 2007

It is impossible to remove toxic organic substances that are recognized as a cancer caused suspicious element in drinking water using the conventional water purification method. This study introduces groundwater into a reaction chamber as an effective amount of water to process this water using a mixed method of AOP oxidation and M/F membrane and purifies it as a desirable level by artificially mixing such toxic substances in order to effectively process the water. Based on this fact, this study configures an optimal operation condition. The VOCs existed in toxic substances was investigated as a term of phenol and toluene, and agricultural chemicals were also investigated as a term of parathion, diazinon and carbaryl. The experiment applied in this study was performed using a single and composite soolution. In the operation condition applied to fully dissolve and remove such substances, the amount of $H_2O_2$ injected in the process was 150 mL of a fixed quantity, the value of pH was configured as $5.5{\sim}6.0$, the temperature was controlled as a range of $12{\sim}16^{\circ}C$, the dissolved amount of ozone was applied more than 5.0 mg/L, the reaction time was determined as an optimal condition, such as $30{\sim}40$ minutes, and the segregation membrane in the same reactor was determined for acquire water drinking of large quantity using a pore size of $0.45{\mu}m$ M/F membrane.

• Journal of Korean Society for Atmospheric Environment
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• v.29 no.5
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• pp.553-573
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• 2013

This paper aims to give a summary and review of the research trend about subjects of Asian Dust (AD) storm in the last three decades. The AD research was focused on classification of synoptic scale data and finding inflow pathway in early stage. Recently, new approaches have been made to explain chemical composition, transportation, transboundary movement reaction of AD, using satellite data, 3D modeling, the aerosol time of flight mass spectroscopy, etc. During AD events, a large amount of dust particles flow into Korea and Japan from AD source areas, and they are highly likely to be mixed with toxic substances when air mass contained AD particles pass over seriously polluted areas. We concluded that, considering that AD events were classified into two cases according to the source area and pathway, the concentrations of crustal components did not increase at the initial stage of AD events, Whereas ammonium-sulfate, trace metal element, OC, EC relatively increased in the early stage. This explains AD events have the possibility of being accompanied with polluted air mass or particles. Also, we further need to compare and summarize the results of AD studies which already have been conducted, and prepare strategies for particle management, particularly for Black Carbon (BC) and Brown Carbon (BrC) which are considered to induce climate change effects.

• The Korea Journal of Herbology
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• v.28 no.4
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• pp.49-55
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• 2013

Objectives : Mori Folium was popularly used as one of the traditional medicinal herbs. Although M. Folium has been cultivated for rearing silkworm historically, it's use has been expanded as natural therapeutic agent for the treatment of filariasis, diabetes and dropsy in East Asia. However, little has been known about the effect of M. Folium on liver fibrosis. Therefore, we would like to explore an anti-fibrogenic potential of M. Folium extract (MFE) using immortalized human hepatic stellate cell line, LX-2 cells. Methods : We examined the effects of MFE on the transforming growth factor ${\beta}1$ ($TGF{\beta}1$)-induced liver fibrosis in LX-2 cells. Cell viability, Smad binding element-driven luciferase activity, phosphorylations level of Smad 2/3, and expression level of $TGF{\beta}1$-dependent target genes were monitored in the MFE-treated LX-2 cells. Results : Up to 30 ${\mu}g/ml$ MFE treatment did not show any possible toxic effect in LX-2 cells. MFE inhibited $TGF{\beta}1$-inducible Smad binding element-driven luciferase activity and decreased the $TGF{\beta}1$-inducible phosphorylations of Smad 2 and Smad 3 in hepatic stellate cell in a dose dependent manner. Furthermore, increases of plasminogen activator inhibitor type 1, $TGF{\beta}1$ and matrix metalloproteinases 2 genes by $TGF{\beta}1$ were also attenuated by MFE treatment. Conclusions : These findings suggested that MFE would be used as a potential therapeutic agent for the treatment liver fibrosis, which might be mediated by the inhibition of $TGF{\beta}1$-inducible Smad 2/3 transactivation and target genes expression.

• Advances in nano research
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• v.15 no.6
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• pp.567-577
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• 2023

The killing of bacteria by mechanical forces on nanopatterned surfaces has been defined as a mechano-bactericidal effect. Inspired by nature, this method is a new-generation technology that does not cause toxic effects and antibiotic resistance. This study aimed to simulate the mechano-bactericidal effect of nanopatterned surfaces' geometric parameters and material properties against three implant-derived bacterial species. Here, in silico models were developed to explain the interactions between the bacterial cell and the nanopatterned surface. Numerical solutions were performed based on the finite element method. Elastic and creep deformation models of bacterial cells were created. Maximum deformation, maximum stress, maximum strain, as well as mortality of the cells were calculated. The results showed that increasing the peak sharpness and decreasing the width of the nanopatterns increased the maximum deformation, stress, and strain in the walls of the three bacterial cells. The increase in spacing between nanopatterns increased the maximum deformation, stress, and strain in E. coli and P. aeruginosa cell walls it decreased in S. aureus. The decrease in width with the increase in sharpness and spacing increased the mortality of E. coli and P. aeruginosa cells, the same values did not cause mortality in S. aureus cells. In addition, it was determined that using different materials for nanopatterns did not cause a significant change in stress, strain, and deformation. This study will accelerate and promote the production of more efficient mechano-bactericidal implant surfaces by modeling the geometric structures and material properties of nanopatterned surfaces together.

• Journal of the Korean Institute of Gas
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• v.14 no.1
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• pp.37-41
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• 2010

The most important element for improving the process safety that occurs from the flare system installed to convert into safe materials by burning the inflammable or toxic gases within the process and this is specified in the API 521 Code so that the radiation does not cause a risk factor. The flames that occur from the flare stack holds the shape of jet fire due to the pressure and flow velocity of discharge gas. This study has identified the shape of flames by using the Chamberlain Model rather than the API 521 Code method, analyzing the radiation due to this.

• Economic and Environmental Geology
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• v.28 no.2
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• pp.147-154
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• 1995

Coal fly ashes collected from the Samcheonpo and the Seocheon Power Plants were analyzed for major and minor components and heavy metals such as As, Cd, Co, Cr, Cu, Ga, Hg, Mo, Ni, Pb, Sb, V and Zn in order to suggest basic data to apply coal fly ash as fertilizer or soil ameliorator. The specific gravity of the samples was less than 2.0, and amounts of organic matter range from 5.0% to 12.3%. The identified minerals by XRD were mainly quartz, mullite and pyrite in anthracite coal, and mainly quartz and mullite in bituminous coal. Generally, the contents of heavy metal elements analyzed were lower less than those of soil, though higher in some samples. Element couples of some elements( e.g., As-Mo, Zn ; Mo-As, Sb, V, Zn ; Sb-Zn ) show positive correlations with each other, but the high correlations of toxic elements such as As, Pb, Cd and Hg indicate to give attention to apply coal fly ash as fertilizer or soil ameliorator.

• Korean Journal of Environmental Agriculture
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• v.29 no.2
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• pp.115-119
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• 2010

Zinc (Zn) is an essential element required for growth and development of plants. However, Zn can be toxic to plants when it presents excessive amount. Phytoextraction is an economic and environment-friendly technique using plants to clean-up metal-contaminated soils. However, the technique cannot be applied in highly metal-contaminated areas because plants will not normally grow in such conditions. Therefore, this research focuses on identifying chelating agents which are biodegradable and applicable to highly metalcontaminated areas. Zn as a target metal and cysteine (Cys), histidine (His), malate, citrate oxalate, succinate, and ethylenediamine (EDA) as biodegradable chelating agents were selected. Plants were grown on agar media containing various chelating agents with Zn to analyze the effect on plant growth. Malate and His slightly increased the inhibitory effect of Zn on root growth of plants, whereas Cys, citrate, oxalate, and succinate did not show significant effects. However, EDA strongly diminished the inhibitory effect of Zn on root growth. The effect of EDA is correlated with decreased Zn uptake into the plants. In conclusion, as biodegradable chelating agents, EDA is a good candidate for growth of plants in highly Zn-contaminated areas.