• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.198.2-198.2
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• 2016

Reactive oxygen and nitrogen species (RONS) can be generated by using non-thermal atmospheric pressure plasma jet which have profound biomedical applications [1, 2]. In this work, reactive oxygen species like hydroxyl radical (OH) are generated by using non-thermal direct plasma jet above water surface using Ar gas and their properties have been studied using ultraviolet absorption spectroscopy. OH radicals are found to be generated simultaneously with the discharge current with concentration of $2.7{\times}1015/cm3$ at 7mm above water surface while their persistence time have been measured to be $2.8{\mu}S$. In addition, it has been shown that plasma initiated ultraviolets play a major role to generate RONS inside water. Further works are going on to measure the temporal behavior of OH and $O2^*-$.

• Journal of the Korean institute of surface engineering
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• v.51 no.2
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• pp.133-137
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• 2018

Plasma devices such as jets, pencils, and torches have been developed as new tools that help penetration of target agents and applied to plasma medicine. However, these devices cannot be used in a large area. Therefore, we introduced a flexible plasma device, which can be treated of large area and designed as bendable plasma. In additional, in vitro model based on agarose gel was prepared that can be show effectiveness in the depth of penetration. Plasma treatment conditions such as power, time and distance can be optimized on the agarose gel wound model. The chemical structure of changed polysaccharides was predicted due to reactive excited atoms and molecules, UV photons, charged particles and reactive oxygen and nitrogen species (RONS).

• Proceedings of the PSK Conference
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• 2005.11a
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• pp.89-90
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• 2005

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.04a
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• pp.430-433
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• 2003

Nitrogen pollution in urban and rural groundwater is a common problem and poses a major threat to drinking water supplies based on groundwater. In this work, the kinetics of nitrification-denitrification coupled reactions are modeled and new reaction modules for the RT3D code describing the fate and transport of nitrogen species, dissolved oxygen, dissolved organic carbon, and biomass are developed and tested. The proposed nitrogen transformations and transport model showed very good match with the results of other public codes.

• Bulletin of the Korean Chemical Society
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• v.35 no.1
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• pp.165-172
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• 2014

The distribution of basic nitrogen-containing compounds in three vacuum gas oils (VGOs) with different boiling ranges and their dewaxed oils from the lube base oil refining unit of a refinery were characterized by positive-ion electrospray ionization (ESI) Fourier transform-ion cyclotron resonance mass spectrometry (FT-ICR MS). It turned out that the composition of basic nitrogen compounds in the samples varied significantly in DBE and carbon number, and the dominant basic N-containing compounds in these oil samples were N1 class species. $N_1O_1$, $N_1O_2$, and $N_2$ class species with much lower relative abundance were also identified. The composition of basic nitrogen compounds in VGOs and dewaxed VGOs were correlated with increased boiling point and varied in DBE and carbon numbers. The comparison of the analytical results between VGOs and dewaxed VGOs indicated that more basic N-containing compounds in VGO with low carbon number and small molecular weight tend to be removed by solvent refining in lube base oil processing.

• Journal of Korean Society of Forest Science
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• v.100 no.4
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• pp.715-721
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• 2011

This study was conducted to estimate aboveground biomass and nitrogen storage potential of tree species-eight clones of a poplar and hybrids, one clone of Salix alba L., dawn redwood (Metasequoia glyptostroboides Hu and W.C. Cheng), yellow poplar (Liriodendron tulipifera L.), Okamoto maple (Acer okamotoanum Nakai), and pin oak (Quercus palustris $M{\ddot{u}}nchh.$)- after treating with liquid pig manure. Stems showed the highest percentage of aboveground biomass, and followed by branches and leaves. Nitrogen content in aboveground biomass components was the highest in leaves, and followed by branches and stems. Average aboveground biomass production was higher in the clones and species treated with manure than those of not treated, 30 ton/ha and 16 ton/ha, respectively. In the manure-treated site, clone 'Dorskamp' of Populus deltoides${\times}$Populus nigra showed the highest aboveground biomass (48.3 ton/ha). Average nitrogen storage potential was superior in the clones and species treated with manure than those of not treated, 159 kg/ha and 90 kg/ha, respectively. Clone 'Dorskamp' also showed the greatest nitrogen storage potential (286.5 kg/ha) among tested tree species. Therefore, 'Dorskamp' is the most suitable clone for treating liquid pig manure, but additional studies are needed to determine any damages or tolerance from the treatment.

• Korean Journal of Environment and Ecology
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• v.21 no.4
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• pp.318-335
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• 2007

Floral study and present vegetation survey were conducted at a representative reclaimed wetland located behind the Rural Research Institute at Ansan, Gyeonggi-do. The importance values were calculated from the ground cover and frequency of recorded species within quadrats and detrended canonical correspondence analysis was conducted using environment variables, such as total nitrogen, electric conductivity, available phosphate, nitrate nitrogen and the distance from the inner roads. And basal areas for the trees encroaching on the reclaimed wetland were estimated to take a look at the on-going situation about the succession routes on land. As a result, 46 families and 158 species of plants were recorded and Pragmites communis was found to be a dominant species as the present vegetation. The ordination analysis results showed that species distribution was purposely explained by total nitrogen in soil and its content in nitrate nitrogen. The invasion of Robinia pseudoacacia and Pinus rigida whose basal areas were $22.3m^2$ and $1.6m^2$ respectively, into the interior areas of the reclaimed wetland was found to cause a disturbance making some parts of the wetland into land. The zoning program using water level control and migratory roads is becoming a contributing factor in destroying a wetland, so it's suggested that some adjustments should be needed to take care of it.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.159-159
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• 2015

A new approach for antimicrobial is based on the overproduction of reactive nitrogen species (RNS), especially; nitric oxide (NO) and peroxinitrite (ONOO-) are important factors to deactivate the bacteria. Recently, non-thermal atmospheric pressure plasma jet (APPJ) has been frequently used in the field of microbial sterilization through the generation of different kinds of RNS/ROS species. However, in previous study we showed APPJ has combine effects ROS/RNS on bacterial sterilization. It is not still clear whether this bacterial killing effect has been done through ROS or RNS. We need to further investigate separate effect of ROS and RNS on bacterial sterilization. Hence, in this work, we have enhanced NO production, especially; by applying a 1% of HNO3 vapour to the N2 based APPJ. In comparison with nitrogen plasma with inclusion of water vapour plasma, it has been shown that nitrogen plasma with inclusion of 1% of HNO3 vapour has higher efficiency in killing the E. coli through the high production of NO. We also investigate the enhancement of NO species both in atmosphere by emission spectrum and inside the solution by ultraviolet absorption spectroscopy. Moreover, qPCR analysis of oxidative stress mRNA shows higher gene expression. It is noted that 1% of HNO3 vapour plasma generates high amount of NO for killing bacteria.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.23 no.3
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• pp.63-79
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• 2020

The present study was to investigate the growth response and nutrient absorption in three willow species (Salix gracilistyla, S. koreensis and S. chaenomeloides) treated with nitrogen source (NH₄⁺:NO₃^- rate; 200:0, 150:50, 100:100, 50:150, 200:0) for a period of 90days. The height, dry weight and chlorophyll contents of three species of willows were found to be highest at 50:150 (NH₄⁺:NO₃^-) treatment. NO₃^--N was more effective than NH₄⁺-N in the early growth of three species of willows. The increase in percentage of NO₃^--N handling, T-N, NO₃^--N in plant tissue increased. The analysis of C, N and mineral content in various parts revealed that the amounts of C, N, K, Ca and Mg were higher in leaves than those in the stems and the roots. However, the amount of NO₃^--N and P were higher in roots than those in the leaves and the stems. Salix koreensis was excellent, followed by S. chaenomeloides and S. gracilistyla in absorption of nitrate nitrogen. Higher percentage of NO₃^--N, the amounts of T-N, NO₃^--N, P₂O₅, K, Na, Ca, and pH in soil were decreased.

• Journal of Environmental Science International
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• v.26 no.10
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• pp.1147-1153
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• 2017

To maintain a rich biological diversity is important to develop for biomaterial resources such as Korean evergreen broad-leaved tree species, the distribution of which is restricted to the southern part of Korean peninsula. We assessed photosynthetic characteristics of Quercus acuta and Castanopsis sieboldii, the representative evergreen broad-leaved trees in Korea, in order to establish a basis for conservation strategy related to distributional change in evergreen broad-leaved tree species according to climate change. Photosynthetic characteristics were evaluated in the sun and shade leaves of the two species. Sun leaves in both species revealed higher light compensation point and maximum photosynthetic rate compared to the shade leaves. In addition, photosynthetic rate was higher in Q. acuta than C. sieboldii, which was supported by a higher leaf nitrogen content and leaf mass per area. Water use efficiency was also higher in Q. acuta as compared to that in C. sieboldii. Similar photosynthetic rate, however, was shown in photosynthetic response to $CO_2$ concentration in the intercellular space. These results suggest that both species could respond differently to the changing environmental factors including climate change, suggesting the possibility of distributional changes resulting from a differential growth rate.