• Journal of the Korean Institute of Landscape Architecture
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• v.37 no.6
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• pp.96-105
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• 2010

This study identified the dynamic process of sandbar and vegetation distribution of the sandbar on the Tan-cheon River. The study area is located in the lower reaches of the Tan-cheon River that has been managed as an Ecosystem Reserve Area since 2002. For the study, the geomorphological process was analyzed through mapping analysis using a satellite image followed by analysis of the vegetation distribution through an on-site survey. The major findings were as follows : First, In the fluvial geomorphic process, various kinds of sandbars were developed in 1990s, the morphologic characteristics changing continuously. Second, In the distribution of vegetation on the sandbar, the sandbar shore was covered with bare sand substrate or intermittent annual vegetation because of the periodic fluctuation of the water-level due to intensive disturbances. Third, In the relationship between the sandbar formation and vegetation, four types of sandbars were classified: channel-shore stable bar, channel-shore unstable bar, mid-channel stable bar and mid-channel unstable bar, according to the fluvial disturbance & vegetation process. The study verifies that the vegetation distribution is reciprocally related to the geomorphological process. Accordingly, it is meaningful in the selection of plant species and the planting area of the sand bar. However, it is limited to the planting guidelines on river restoration projects. More diverse on-site experimental studies should be conducted.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.3
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• pp.542-552
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• 2018

In this paper, the precast method of a concrete eco-pillar debris barrier was proposed to improve the construct ability and economic efficiency. The performance was validated by experimental and structural analysis. The steel debris barrier has a high construction cost and causes environmental damage with corrosion. The construction of a concrete eco-pillar debris barrier has been increased recently. On the other hand, there are no design standards regarding debris barriers in Korea, and debris barriers are being designed by the experience and sense of engineers. Therefore, in this study, a method to determine the design external forces was proposed and the design was performed by applying a hollow cross-section to the debris barrier. In addition, three types of connection methods of a concrete cantilever column with the maximum bending moment acts were proposed, and validation of the performance of each type was performed with a real-scale experiment. The experimental results showed that the type with loop reinforcement had the highest rigidity and the type with anchorage performance exceeded the maximum bending moment according to the ultimate load. In the manufacturing procedure of mock-up debris barriers, the type with an anchorage-bar was found to have superior construct ability.

• Journal of the Korea Organic Resources Recycling Association
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• v.23 no.3
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• pp.33-41
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• 2015

An alternative was investigated to maximize the treatment efficiency of wastewater treatment plant without large scale expansion. 79% of detention time was required for enough nitrogen control. As aeration time was extended, nitrification was processed, but opposite trend was seen in phosphorus. High concentration of $NO_3-N$ interrupted PAOs activity not to absorb phosphorus. An alternative was devised for selective use of anaerobic or anoxic zone. Trisection was suggested for alternative use of center room. The result was relatively successful. The concentration of phosphorus was reduced with reduction of nitrogen. Extended anaerobic condition seemed to stimulate denitrification. Valve connection of internal return from aeration tank will make it possible to use middle room alternatively. This method will be a good alternative for seasonal variation of water temperature.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.4
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• pp.628-634
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• 2012

Release of veterinary antibiotics (VSs) to agricultural environment through application of animal manure and/or animal manure-based composts to soils is of concern. The current study was conducted to examine decline of VAs during composting the chicken manure. For this, antibiotics free chicken manure (20 kg) and sawdust (10 kg) were added to the bench-scale composting apparatus and then the mixed material was spiked simultaneously with three VAs (chlortetracycline, CTC; sulfamethazine, SMZ; tylosin, TYL) at two different levels (10 and $20mg\;kg^{-1}$). Then the decline of VAs was determined using Charm II system during 53 composting period. For comparison, composting only chicken manure was included at VAs concentration of $10mg\;kg^{-1}$. During composting, the concentration of all three different VAs declined below the prospective guideline values ($0.8mg\;kg^{-1}$ for CTC, $0.2mg\;kg^{-1}$ for SMZ, and $1.0mg\;kg^{-1}$ for TYL) except CTC at $20mg\;kg^{-1}$ spiking when the chicken manure was composted together with sawdust. Interestingly, CTC at $10mg\;kg^{-1}$ spiking appeared to be declined under the guideline value without sawdust while SMZ was resistant to be declined without sawdust. Unlike CTC and SMZ, TYL showed immediate decline right after spiking TYL to composting materials regardless the spiking concentration and existence of sawdust. Appropriate composting procedure of chicken manure was able to decline the residual VAs in the manure below the prospective guideline value and the importance of organic substances on this decline was perceived.

• Journal of Korean Society of Environmental Engineers
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• v.38 no.1
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• pp.34-41
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• 2016

Using UF-SWRO hybrid process, pre-blending tests of seawater and brackish water were performed to investigate the effects on removal of boron and humic acid (HA). Feedwater pre-blending was set based on TDS concentration from 15,000 mg/L to 27,000 mg/L and analyzed for boron removal characteristics. Also organics rejection at same TDS concentration range was investigated by injecting HA. Boron concentration appeared to be high as TDS concentration was high ranging from 76.60% to 83.27%, but boron concentration in final produced water was increased up to 0.69 mg/L from 0.48 mg/L. In cases of HA tests at 10 mg/L, 22,500 mg/L TDS appeared to be higher removal rate of 17.59% than a very poor result of 8.43% in 27,000 mg/L. But high HA removal rate of 57.14% was obtained in produced water with 22,500 mg/L TDS containing 10 mg/L of HA and 27,000 mg/L TDS yielded lower boron removal rate of 54.49%. Meanwhile it was found that a relatively high flux and recovery rate were obtained following process when feedwater was injected with HA. It is considered that most of fouling substances were eliminated by binding between HA and $Ca^{2+}$. Thus, when desalination using UF-SWRO with respect to boron and HA, TDS concentration is determined to be advantageous as lower.

• Applied Biological Chemistry
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• v.46 no.2
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• pp.134-139
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• 2003

To establish the fertilization condition to increase the productivity of Chasanthemum boreale M. with high quality, the effects of three nutrients (N, P, K) on the yields and the effective components were investigated in the pot scale. NPK was applied by chemical fertilizers with $(N-P_2O_5,-K_2O=250-160-160\;kg/ha)$ as a main treatment, and NP $(N-P_2O_5,-K_2O=250-160-160\;kg/ha)$, NK $(N-K_2O =250-160\;kg/ha)$, and PK $(P_2O_5K_2O=160-160\;kg/ha)$ treatments were settled as comparison. Dry yields of C. boreale M. was increased significantly to 4 fold higher by nitrogen. Nitrogen increased apparently plant growth and inorganic nutrient uptake. In the flower, which is most useful and edible part as a herbal medicine, main amino acids were glutamic acid and aspartic acids, and the total content was increased significantly by three elements of application. In addition, the content of cumambrin A, which is known to have the effect of blood-pressure reduction, was increased source to 6.2 times by nitrogen higher than that in PK treatment. Potassium was more effective in biosynthesis of cumambrin A than phosphorus, but the biological pathway was not clear, still.

• Journal of Energy Engineering
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• v.24 no.3
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• pp.150-163
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• 2015

Gasification technology is one of the representative next-generation fossil fuel utilization technologies, converting low grade fossil fuels such as coal, heavy residue oil, pet-coke into highly clean and efficient energy sources. Accordingly, related market demand for gasification technology is ever increasing steadily and rapidly. A few years ago, conventional pulverized coal utilization technology had an edge over the gasification technology but the most significant technical barrier of limited capacity and availability has been largely overcome nowadays. Futhermore, it will be more competitive in the future with the advancement of related technologies such as gas turbine, ion transfer membrane and so on. China has recently completed a commercialization-capable large-scale coal gasification technology for its domestic market expansion and foreign export, rapidly becoming a newcomer in the field and competing with existing US and EU technical leadership at comparable terms. Techno-economic aspect deserves intensive attention and steady R&D efforts need to continue in organized, considering that gasification technology is quite attractive combined with $CO_2$ capture process and coal to SNG plant is economically viable in Korea where natural gas is very expensive. In the present paper, recent technology development and commercialization trend of many leading companies with coal gasification expertise have been reviewed with significant portion of literature cited from the recently held '2014 Gasification Technology Conference'.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.8
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• pp.679-689
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• 2009

Light olefins are very important hydrocarbons widely used as the raw materials of the most petrochemicals including plastics and medicines. In addition, the nation's olefin production capacity is regarded as one of the key indicators to predict the nation's economic scale and growth. Steam cracking of naphtha (or called "NCC (Naphtha Cracking Center) technology"), the traditional process to produce light olefins, is one of the most consuming energy processes among the chemical industries. Therefore, this process causes tremendous $CO_2$ emission. To reduce the energy consumption and $CO_2$ emission from NCC process, the present paper, firstly, investigates and analyses some alternative technologies which can be potentially substituted for traditional process. Secondly, applying the alternative technologies to NCC process, their effects such as energy savings, $CO_2$ emission reduction and CER (Certified Emission Reduction) were estimated. It is found that the advanced NCC process can reduce approximately 35% of SEC (Specific Energy Consumption) of traditional NCC process. This effect can lead to the reduction of 3.3 million tons of $CO_2$ and the acquisition of the 128 billion won of CER per year. Catalytic cracking of naphtha technology, which is other alternative processes, can save up to approximately 40% of SEC of traditional NCC process. This value equates to the 3.8 million tons of $CO_2$ mitigation and 147 billion won of CER per year.

• The Korean Journal of Quaternary Research
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• v.17 no.2
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• pp.17-23
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• 2003

In Korea terrestrial fluvial sequences can be used as pedological and sedimentological markers indicating a millenium-scale environmental and climatic changes imprinted in fluvial sub-environments, which in turn are represented by the cyclicity of fluvial sands, backswamp organic muds, and flooding muds intercalations of frostcracked or dessicated brown paleosols. Post LGM and Holocene fluvial and alluvial sedimentary sequences of Korea are formed in such landscapes of coastal, floodplain, backswamp and hillslope areas. Among them, the most outstanding depositional sequences are fluvial gravels, sands and organic mud deposits in coastal, fluvial, or alluvial wetlands. The aim of this study is to explain the sedimentary sequences and palynofloral zones since the last 15,000years, on the basis of organic muds layers intercalated in fluvial sand deposits. Jangheung-ri site of Nam river, Soro-ri site of Miho river, Youngsan rivermouth site in Muan, Oksan-ri site of Hampyeong and Sanggap-ri site of Gochang are illustrated to interpret their sedimentary facies, radiocarbon datings, and palynofloral zonation. Up to the Middle to Late Last Glacial(up to 30-35Ka), old river-bed, flooding, and backswamp sequences contain such arboreal pollens as Pinus, Abies, and Picea, and rich in non-arboreal pollens like Cyperaceae, Gramineae, Ranunculaceae, and Compositae. During the LGM and post-LGM periods until Younger Dryas, vegetation has changes from the sub-alpine conifer forest(up to about 17-11Ka), through the conifer and broad-leaved deciduous forest, or mixed forest (formed during 16,680-13,010yrB.P), to the deciduous and broad-leaved forest (older than 9,500yrB.P). In the Earliest Holocene flooding deposits, fragments of plant roots are abundant and subjected to intensive pedogenic processes. During Holocene, three arboreal pollen zones are identified in the ascending order of strata； Pinus-Colyus zone(mixed conifer and deciduous broad-leaved forest, about up to 10Ka), Alnus-Quercus forest (the cool temperate deciduous broad-leaved forest, about 10Ka-2Ka), and Pinus forest (the conifer forest, about after 2Ka), as examplified in Soro-ri site of Cheonwon county. The palynological zonations of Soro-ri, Oksan-ri, Sanggap-ri, Youngsan estuary, and Gimhae fluvial plain have been recognized as a provisional correlation tool, and zonations based on fluvial backswamp and flooding deposits shows a similar result with those of previous researchers.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.3
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• pp.1288-1295
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• 2012

Korea Ministry of Knowledge Economy has estimated that wind power (WP) will be occupied 37% in 2020 and 42% in 2030 of the new energy sources, and also green energies such as photovoltaic (PV) and WP are expected to be interconnected with the distribution system because of Renewable Portfolio Standard (RPS) starting from 2012. However, when a large scale wind power plant (over 3[MW]) is connected to the traditional distribution system, protective devices (mainly OCR and OCGR of re-closer) will be occurred mal-function problems due to changed fault currents it be caused by Wye-grounded/Delta winding of interconnection transformer and %impedance of WP's turbine. Therefore, when Double-Fed Induction Generator (DFIG) of typical WP's Generator is connected into distribution system, this paper deals with analysis three-phase short, line to line short and a single line ground faults current by using the symmetrical components of fault analysis and PSCAD/EMTDC modeling.