• Korean Journal of Remote Sensing
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• v.29 no.4
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• pp.351-360
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• 2013

Harmonic analysis enables to characterize patterns of variation in MODIS NDVI time series data and track changes in ground vegetation cover. In harmonic analysis, a periodic phenomenon of time series data is decomposed into the sum of a series of sinusoidal waves and an additive term. Each wave is defined by an amplitude and a phase angle and accounts for the portion of variance of complex curve. In this study, harmonic analysis was explored to tract ground vegetation variation through time for land-cover vegetation change detection. The process also enables to reconstruct observed time series data including various noise components. Harmonic model was tested with simulation data to validate its performance. Then, the suggested change detection method was applied to MODIS NDVI time series data over the study period (2006-2012) for a selected test area located in the northern plateau of Korean peninsula. The results show that the proposed approach is potentially an effective way to understand the pattern of NDVI variation and detect the change for long-term monitoring of land cover.

• Journal of Wetlands Research
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• v.2 no.1
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• pp.59-67
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• 2000

The aim of this study is to identify the role of this natural treatment system, which consists of Oenanthe javanica and wasted concrete as bio-media. Therefore, it was designed to experiment water quality, BOD, SS, T-N, T-P to recognize the efficiency of treatment system with one biofilter tank using wasted concrete and vegetation bed using Oenanthe javanica. It was also designed to compare two different biofilter reactors, which are air lift and upflow methods. In the result, it was demonstrated that upflow method is more efficient system to control water quality of polluted streams. The vegetation bed using Oenanthe javanica has the treatment efficiency of 41 % (BOD), 52 % (COD), 60% (SS), 36 % (T-P), 70 % ($NH_4-N$). It was therefore proved that removal rates of nutrients are not so good except $NH_4-N$ concentration with nitrification.

• Environmental Engineering Research
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• v.14 no.1
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• pp.53-60
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• 2009

The main objective was to develop and assess a dynamic fate and transport model for lead in air, soil, sediment, water and vegetation. Daejeon was chosen as the study area for its relatively high contamination and emission levels. The model was assessed by comparing model predictions with measured concentrations in multi-media and atmospheric deposition flux. Given a lead concentration in air, the model could predict the concentrations in water and soil within a factor of five. Sensitivity analysis indicated that effective compartment volumes, rain intensity, scavenging ratio, run off, and foliar uptake were critical to accurate model prediction. Important implications include that restriction of air emission may be necessary in the future to protect the soil quality objective as the contamination level in soil is predicted to steadily increase at the present emission level and that direct discharge of lead into the water body was insignificant as compared to atmospheric deposition fluxes. The results strongly indicated that atmospheric emission governs the quality of the whole environment. Use of the model developed in this study would provide quantitative and integrated understanding of the cross-media characteristics and assessment of the relationships of the contamination levels among the multi-media environment.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.18 no.4
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• pp.1-14
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• 2015

A manipulation of zoysiagrass's lateral stems and soil-media; used for slope revegetation, is expected to facilitate the production of high-quality grass. To study the influences on the growth of zoysiagrass depending upon various soil-media conditions, two different types of soil are used. The results obtained - through investigation of its cover rates, leaf color and number - are summarized as follows. In mountain regions soil, there are no significant differences in growth and development of grass in treatments: zoysiagrass's lateral stems treatments with 1cm, 2cm, and 3cm soil-media and treatment with only seeding. Zoysiagrass, in most of the treatments, show about the same growth rates, and at the end, fair visual quality. Zoysiagrass's lateral stems treatments with 2cm, 3cm show slightly better growth, however, thickness of soil-media need not be more than 1cm to obtain an expected quality of lawn. In decomposed granite soil, there appears statistical significance in growth of the grass in treatments: zoysiagrass's lateral stems treatments with 1cm, 2cm, and 3cm soil-media and treatment with only seeding. The thicker the soil-media, the better the growth of grass, and that in treatment with seeding-only shows poor quality in general. And therefore, it is efficacious to plant in 3cm soil-media when quick formation of lawn is necessary; however, using 2cm soil-media is ultimately the most cost-efficient way of formation. But, when time allows - that is, more than three months - 1cm soil-media in decomposed granite soil is reasonable to formate just as effective lawn. And so when performing seeding, additional covering, fertilization or increasing the quantity of seed must be considered.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.12 no.3
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• pp.33-48
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• 2009

A palustrine wetland is a type of a wetland that prevails in Korea as well as an ecosystem that provides various ecological functions and has affluent biodiversity. This study was conducted to understand the characteristics of vegetation in a palustrine wetland by analyzing a life form and naturalized plants, in order to present the maintenance and utilization plan of a small wetland. A total of 249 taxa including 76 families, 188 generics, 209 species, 38 varieties and 2 forma were found at six investigated wetlands. As a result of the appearance ratio analysis, Therophytes (37.8%) with 94 taxa and Hemicryptophytes (31.3%) with 78 taxa were in order of life form, and Gramineae (14.1 %) with 35 taxa and Compositae (11.2 %) with 28 taxa were in order of family level. These were deemed representative vegetation in a palustrine wetland. Equosetum arvense, Phragmites communis, Commelina communis, Persicaria thunbergii, Arenaria serpyllifolia, Stellaria media, Erigeron annuus, Erigeron canadensis and Artemisia princeps var, orientalis were found continuously for a period of investigation in all sites. Equosetum arvense, Phragmites communis and Persicaria thunbergii were species with high appearance frequency. Especially, Persicaria thunbergii was construed high in a cover ratio in May as it develop first among Hydrophytes and form a canopy sooner than anything else. We found that a degree of naturalization and an urbanization index appear comparatively high in Yeongok-ri, Cheonan, Gangjang-ri, Asan and Yodang-ri, Hwasung, which is construed due to artificial interference, such as fanning, fishing, swimming and green-tour program. These results would be used to utilize in restoring a deserted and damaged wetland and to provide fundamental data in creating a wetland as follows.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.9
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• pp.24-33
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• 2017

Multitemporal MODIS vegetation index (VI) data are widely used in vegetation monitoring research into environmental and climate change, since they provide a profile of vegetation activity. However, MODIS data inevitably contain disturbances caused by the presence of clouds, atmospheric variability, and instrument problems, which impede the analysis of the NDVI time series data and limit its application utility. For this reason, preprocessing to reduce the noise and reconstruct high-quality temporal data streams is required for VI analysis. In this study, a data reconstruction method for MODIS NDVI is proposed to restore bad or missing data based on the statistical properties of the oscillations in the NDVI temporal dynamics. The first derivatives enable us to examine the monotonic properties of a function in the data stream and to detect anomalous changes, such as sudden spikes and drops. In this approach, only noisy data are corrected, while the other data are left intact to preserve the detailed temporal dynamics for further VI analysis. The proposed method was successfully tested and evaluated with simulated data and NDVI time series data covering Baekdu Mountain, located in the northern part of North Korea, over the period of interest from 2006 to 2012. The results show that it can be effectively employed as a preprocessing method for data reconstruction in MODIS NDVI analysis.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.9 no.1
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• pp.41-54
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• 2006

In case of leaving artificial slopes resulting from large-scale constructions, there may be secondary damage caused by soil loss due to erosion and collapse. Furthermore, slope-restoring constructions have a few problems such as monotonous landscape and difficult succession of secondary vegetation due to reckless use of exotic grass, despite attaining the initial purpose of revegetation. To settle this problem, selected plants deemed to be proper for revegetation were used on one of thin vegetation base methods, CODRA SYSTEM, and made seeding mixture experimental plots considering germination rates differing in each season. Native herbs, native shrubs and exotic herbs contents were increased by 30% and 50% respectively, centered on seeding quantity(30g/$m^2$) used as design standard in the seed spray method, in order to figure out proper quantity for revegetation in each season.

• Korean Journal of Ecology and Environment
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• v.41 no.spc
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• pp.93-98
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• 2008

We investigated the effect on the removal of BOD, SS, TN and TP and algal growth inhibition of Vegetated Artificial Floating Island (VAFI), by examining microorganism activity and nutrient uptake in the batch test of various conditions: (1) Blank (Control group), (2) VAFI of $0.25m^2$, (3) AFI of $0.25m^2$ which has no vegetation, (4) buoyant plate of $0.25m^2$, (5) buoyant plate of $0.25m^2$ with linear media. The proportion of BOD removal in the VAFI, AFI, buoyant plate and buoyant plate with media were 82.7, 80.8, 45.2% and 59.6% respectively. TN removal in the VAFI, AFI and buoyant plate with media were 51.2, 31.7% and 25.1% respectively. TP removal in the VAFI, AFI, buoyant plate and buoyant plate with media were 23.3, 16.7, 10.0% and 13.3% respectively. Chlorophyll-${\alpha}$ removal in the VAFI was 97.9%. The factors of chlorophyll-${\alpha}$ removal in the VAFI accounted for the shading effect of 35.1%, microorganisms activity of 61%, and plant root of 1.8%.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.10 no.4
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• pp.70-82
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• 2007

Aiming at nature's early restoring needs to select plant species harmonizing with surrounding environment that fits to restoring goal of ultimately aiming at woody plants dominant vegetation that protect and stabilize surface parts of bared slopes. And it is important to make it assimilated with surrounding natural vegetation by differentiating planning of seed mixtures. Natural Ecological Restoring Construction Methods (JSB Method) was developed to increase the effect of landscape change according to seasons not to simple hydro-seeding by reducing rate of foreign grasses while raising rate of wild flower using. It was considered that using wild flowers that bloom on each season solved the problems of slope landscapes that looks artificial and uninteresting. After researching environmental condition of the slopes, JSB Method has shown that, as of wet-type method, soil is relatively soft and the difference of thickness of plant base soil media affects on the difference of soil hardness. In case of soil hardness of 8.8~17mm, there's dangerousness of slope's collapsing, but it has shown that growth of plant was favorable. For the acidity of soil, most of them are in the type of neutralized soil of more than pH 6. And after analyzing the degree of woody plants dominance, it had shown that lower part was occupied with wild flowers and other herbaceous species like China pin, golden phesant mum, pitcher plant, and middle and upper part was occupied with woody plants like silk-tree, sumac forming multi-layer structure. It can be concluded that the restoration objects of the woody plant vegetation on the roadside slopes can be accomplished successfully by Natural Ecological Restoring Construction Method (JSB method).

• Journal of Korean Society of Water and Wastewater
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• v.32 no.6
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• pp.487-497
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• 2018

Water quality improvement processes for stagnant area consist mainly of technologies applying vegetation and artificial water circulation, and these existing technologies have some limits to handle pollution loads effectively. To improve the purification efficiency, eco-friendly technologies should be developed that can reinforce self-purification functions. In this study, a multi-functional floating island combined with physical chemical biological functions ((1) flotation and oxidization using microbubbles, (2) vegetation purification and (3) bio-filtration with improved adsorption capacity) has been developed and basic experiments were performed to determine the optimal combination conditions for each unit process. It has been shown that it is desirable to operate the microbubble unit process under conditions greater than $3.5kgf/cm^2$. In vegetation purification unit process, Yellow Iris (Iris pseudacorus) was suggested to be suitable considering water quality, landscape improvement and maintenance. When granular red-mud was applied to the bio-filtration unit process, it was found that T-P removal efficiency was good and its value was also stable for various linear velocity conditions. The appropriate thickness of filter media was suggested between 30 and 45 cm. In this study, the optimal design and operating parameters of the multi-functional floating island have been presented based on the results of the basic experiments of each unit process.