• Journal of the Korean association of regional geographers
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• v.13 no.4
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• pp.422-437
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• 2007

Dokdo has historical and political meaning in relation to the territorial problems with Japan. The area can be the main factor to explain the formation and development process of East-Sea as exposure volcanic island at East-Sea with Ulreong-island. Accordingly, it also has an important meaning of physical geography aspects In this research, it is perceived the geomorphological development process of slope due to the salt weathering which is considered as the most important factor to understand whole geomorphology of Dokdo. And researched how a geomorphology of this sort affects to animal and plants. The peculiar geomorphology is tafoni which is a weathering geomorphology and one of the remarkable geomorphology in preservation of Dokdo. Tafoni at west part of Dongdo is distributed intensively near shoreline which is composed tuff. The shape of tafoni is mainly massive, circle and oval in Massive tuff breccia layer also is formed toward horizontality bedding direction in Bedded lapilli tuff. Tafoni in Dokdo is constituted after middle of Holocene. This fact can be proved by ranging at surface of sea-cliff which is formed wave erosion after middle of Holocene sea-level reaching to present level. Tafoni is also the most contribute factor of geomorphology dissection of Dokdo as it is eroded the bed rock with salt weathering. In bottom part of tafoni it has an important function for habitat of birds. Herbaceous plants are on it. To procrastinate of bed rock dissection by growth of Tafoni, conservation of vegetation and soil are most important factor.

• Journal of Forest and Environmental Science
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• v.28 no.4
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• pp.212-219
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• 2012

An experiment was set to understand the seedlings growth and nodulation capabilities of five potentially important leguminous agroforestry tree species of Bangladesh in response to application of organic fertilizer. Study was carried out in nursery bed on the seedlings of Acacia mangium Willd., Acacia hybrid, Acacia auriculiformis A. Cunn. ex Benth, Albizia lebbeck (L.) Benth. and Leucaena leucocephala (Lam.) de Wit. after sowing their seeds in polybags filled with different medium. Farmyard manure or decomposed cow dung was applied as the source of organic fertilizer with other potting media. The growth and nodulation performance of seedlings of the selected species were measured three moths after the first seed was emerged. The different soil: organic manure ratios' used during the experiment were, 1:1, 2:1 and 3:1. The effects of organic fertilizer on growth and nodulation were compared to that of seedlings grown in control. The results revealed a positive correlation between seedling growth and the different doses of organic fertilization (i.e. seedling growth was enhanced significantly with different treatments containing higher proportion of organic fertilizer). In few cases a negative effect was observed after applying higher levels of organic manure. It was also apparent that the nodulation in terms of nodule number and size was inhibited significantly by the application of organic fertilizer.

• Journal of the Korean Institute of Rural Architecture
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• v.21 no.4
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• pp.45-52
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• 2019

Chemical grouting method is mainly used for construction of dams and reservoirs, stabilization and reinforcement of slopes, reinforcement of soft grounds such as embankments, dredging and landfills, the order of earthquake response method, and the reinforcement of structures. Recently, it is widely applied in construction sites such as highways, airfields, high-speed railways, subsea facilities, port construction works, tunnels, and subway works. As such, the demand for grouting continues to increase. The development of the grouting method was focused on increasing the strength of the ground, and the development of the chemical additives, the injection device, and the stirring device were mainly performed. But ordinary portland cement used for grouting is a product that consumes natural resources such as limestone, generates a large amount of greenhouse gases, consumes a large amount of energy sources, and it is time to develop products and new methods to replace them. In this study, Ordinary Portland Cement and New Grouting Binder (circulating fluidized bed boiler fly and blast furnace slag) were compared and analyzed by the following test. Homo-gel strength and homo-gel time, water quality analysis of the water used and soil contamination process tests of homo-gel samples were performed. In the case of NGB, when Using water is used as the reservoir water, the strength measured smaller than that of the other water. However, it shows about 2.5 times greater than the homo-gel compressive strength applied to OPC (7-day, reservoir water), so there is no problem with water quality when applied.

• Korean Journal of Medicinal Crop Science
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• v.4 no.3
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• pp.265-268
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• 1996

According to the research of the cultivation result of Gardenia for 5 years to investigate its cultivation conditions and problems, the development of the variety with early mature and high yielding is urgent and that of rooted cutting cultivation method by the experiment of rooted cutting, bed soil, growth regulator and cutting period are pressing. The development of cultivation method with planting year, planting density, supplementary period and amounts of supplementary of Gardenia planted on growing field are required and for the disease and insect pest control, the research of the cultivation method with disease and insect pest resistance is ne­eded by auxotrophic fertilizing and organic agricultural method, not by agriltural chemicals.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.1
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• pp.121-130
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• 1993

The major objective of this study is to develop practical methods for estimating sediment yield rates of medium size watersheds of which areas range from 200 to $2,000km^2$. For this purpose, this study adopts an empirical method of statistical approach and another empirical method of weighting the watershed characteristics factors. A total of 13 data points for sediment yield rate, including five data points from reservoir deposit data and eight data points from sampled river-sediment data have been collected. Meanwhile, seven factors that may affect the sediment yield rate of a watershed have been selected. They are drainage density, rainfall erosivity, ground cover and land use, soil erodibility, topography, river-bed material characteristics, and watershed area. In the companion paper following this paper, methods for estimating sediment yield rate are to be developed using the 13 data points collected and seven watershed characteristics factors selected in this study.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.48 no.3
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• pp.205-208
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• 2003

This study was conducted to develop a technology for raising rice hydroponically seedlings using the bed in which the seedlings grew in nutrient solution without soil. In Hydroponic rice seedlings, two nutrient solutions (Yashida and Wonsi) were evaluated with four supplying methods $[$3 times (2 days, 8 days and 12 days after seeding), 2 times (5 days and 10 days after seeding), and 1 time (5 days and 10 days after seeding)$]$1, Seedling growth was not different between the two solutions. However, tensile strength of root-mat was higher in Yoshida solution than in Wonsi solution. The more frequent supply of solution resulted in the better seedling growth but in the weaker root mat. Utilization efficiency of the solution minerals was not different in N content regardless of supplying frequencies, but higher in r, K, Ca and Mg when supplied only once on the 5 days after seeding.

• Geomechanics and Engineering
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• v.4 no.4
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• pp.281-294
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• 2012

Filtration using granular media such as quarried sand, anthracite and granular activated carbon is a well-known technique used in both water and wastewater treatment. A relatively new pre-filtration method called pebble matrix filtration (PMF) technology has been proved effective in treating high turbidity water during heavy rain periods that occur in many parts of the world. Sand and pebbles are the principal filter media used in PMF laboratory and pilot field trials conducted in the UK, Papua New Guinea and Serbia. However during first full-scale trials at a water treatment plant in Sri Lanka in 2008, problems were encountered in sourcing the required uniform size and shape of pebbles due to cost, scarcity and Government regulations on pebble dredging. As an alternative to pebbles, hand-made clay pebbles (balls) were fired in a kiln and their performance evaluated for the sustainability of the PMF system. These clay balls within a filter bed are subjected to stresses due to self-weight and overburden, therefore, it is important that clay balls should be able to withstand these stresses in water saturated conditions. In this paper, experimentally determined physical properties including compression failure load (Uniaxial Compressive Strength) and tensile strength at failure (theoretical) of hand-made clay balls are described. Hand-made clay balls fired between the kiln temperatures of $875^{\circ}C$ to $960^{\circ}C$ gave failure loads of between 3.0 kN and 7.1 kN. In another test when clay balls were fired to $1250^{\circ}C$ the failure load was 35.0 kN compared to natural Scottish cobbles with an average failure load of 29.5 kN. The uniaxial compressive strength of clay balls obtained by experiment has been presented in terms of the tensile yield stress of clay balls. Based on the effective stress principle in soil mechanics, a method for the estimation of maximum theoretical load on clay balls used as filter media is proposed and compared with experimental failure loads.

• Journal of the Korean Society of Groundwater Environment
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• v.4 no.4
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• pp.169-174
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• 1997

Stream water and precipitates were analyzed for metal contents to evaluate the compositional changes of effluent water from mine waste Danbung mine located in the vicinity of Munkyung. Samples were collected before and after the rainy season in 1995 and before the rainy season in 1997 to observe seasonal variation and the charge of the status of pollution after the lapse of two years. Increased metal contents and lowered pH values after rainy season are thought of the results of flushing of oxidation products of pyrite accumulated during dry season in mine wastes. The results of two years later showed that pollution by AMD have progressed more seriously in that pH has been lowered by one order and metal contents increased about twice. The spatial distribution of various Fe, Al hydroxides and sulfates occurring as red and white precipitates also changed. Red precipitates occurred at stream bed in longer distance after two years and white precipitates occurred far down from the mine wastes where no precipitates had been observed 1995. And metal contents in sediments also increased up to more than ten times.

• Journal of Korean Society on Water Environment
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• v.23 no.5
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• pp.723-730
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• 2007

This study was conducted to develop a combined method for remediating a Chlorinated Aliphatic Hydrocarbons (CAHs) mixtures-contaminated aquifer. The process is consist of two processes. A chemical process (1st) using natural zinc ores for reducing higher concentrations of CAH mixtures to the level at which biological process is feasible; and A biological process (2nd) using aerobic cometabolism for treating lower concentration of CAH mixtures (less than 1 mg/L). Natural zinc ore showed relatively high transformation capacity, average dehalogenation percentage, and the best economic efficiency in previously our study. To evaluate the feasibility of the process, we operated two columns in series (that is, chemical and biological columns). In the first column filled with natural zinc ore and sand, CAH mixtures were effectively transformed with more than 95% efficiency, the efficiency depends on the Empty Bed Contact Time (EBCT) and the mass of zinc ore packed. Scanning Electron Microscope (SEM), X-Ray Diffraction (XRD) analysis were performed to make sure whether natural zinc ore played an key role in the dechlorination of the CAH mixtures. The characteristics of zinc metal surface changed after exposure to CAHs due to oxidation of $Zn^0$ to $Zn^{2+}$. In the biological column injecting propane, DO and effluent of the chemical column, only 1,1,1-TCA was cometabolically transformed. Consequently, the combined process would be effective to remediate an aquifer contaminated with high concentrations of CAH mixtures.

• Water for future
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• v.26 no.1
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• pp.81-91
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• 1993

In this paper, a moving storm in the real watershed was simulated using a distributed model. Macks Creek Experimental Watershed in Idaho, USA was selected as a target watershed and the moving storm of August 23, 1965, which continued from 3:30 P.M. to 5:30 P.M., was utilized. The rainfall intensity of the moving storm in the watershed was temporally varied and the storm was continuously moved from one place to the other place in a watershed. Furthermore, runoff parameters, which are soil types, vegetative cover percentages, overland plane slopes, channel bed slopes and so on, are spatially varied. The model developed in the previous paper was utilized as a distributed model for simulating the moving storm. In the model, runoff in a watershed was simulated as two parts which are overland flow and channel flow parts. The good agreement was obtained between a simulated hydrograph using a distributed model and an observed hydrograph. Also, the conservations of mass are well indicated between upstream and downstream at channel junctions.