• Journal of Korean Society of Water and Wastewater
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• v.20 no.1
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• pp.3-11
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• 2006

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2004.11a
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• pp.44-44
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• 2004

• Journal of the Korean Institute of Landscape Architecture
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• v.30 no.4
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• pp.1-8
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• 2002

The place of South Weol Dynastys authorities exhumed in the region of KangChoWu, China lies adjacent to a stone ditch through which water streams crookedly, and a dark trough of stone pond in the north side. There is a sharply curved stone ditch and a crescent-shaped water entrance made by stones. The place was separated by using stone columns and stone walls. There is a beam of ditch, a crooked entrance, a flat bridge of slate, a stepping-stone, a sluice gate, and a crooked corridor. There are big and small artificial islands, and reinforcing stone drainage way in the palace pond recently exhumed at the building site for the pavilion of Hwang-Yong Temple in Kuhwang-Dong, Gyeongju city, Korea. There are four facilities assumed to be entrance and exits at four corners and an open space on which gravel was spread extensively. A narrow road and a middle road with indefinite curves at the south of Asukakyoseki exhumed by the first, second and third and two stone buckets which one is to fill with water and the other is to drain water off like fountain are there, and besides wave protecting dam and north pond and the part that water pass were excavated. Palace ponds that were extensively distributed at old residential cities are a general phenomenon of countries in eastern Asia. Anap pond of Silla and Gungnam pond of Baekje were in Kroea. We believe that Asutnkyoseki is on the extension. Although more investigations in the background of thought and the genealogical relation about the palace pond are required, it seems that an idea was surely received from China.

• Journal of Environmental Health Sciences
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• v.37 no.1
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• pp.64-72
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• 2011

This study was performed to assess the removal efficiency on nitrogen, phosphorus and organic carbon in wastewater by spatial separation and internal recycling in a modified oxidation ditch process (modified OD). The performances of the modified OD were evaluated via laboratory-scale experiments. The process was operated at hydraulic retention times of 6-48 hours and solid retention times of 17-38 days. We found that organic carbon removal efficiency increased after the modified OD operation period. T-N removal efficiency remained stable; average T-N concentration of effluent was 8.02 mg/l after modified OD operation. In contrast, T-P concentration of effluent was over 1 mg/l. Nitrogen and phosphorus removal efficiency of modified OD at HRT 12 hr were 83.1% and 74.1%, respectively. Also, maximum efficiency was found at SRTs from 20 to 30 days. T-N removal efficiency was 83.1% at a C/N ratio from 3.0 to 3.5. However, T-N removal efficiency decreased at C/N ratios over 3.5. Also, T-P removal efficiency increased with HRT at C/P ratios in the same condition. Maximum efficiency was 74.1% at a C/P ratio from 25 to 28. T-N removal efficiency was 79.2% and T-P removal efficiency was 65.3% after M4 mode operation (added to the internal recycle line connected to the anoxic reactor). The modified OD with spatial separation and internal recycling developed in this study is, therefore, believed to be an improvement for solving problems in the nutrient removal technologies.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.2 no.3
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• pp.83-92
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• 1999

To investigate the influence of forest road characteristics and site conditions on the stability of forest-road in granite area, four forest roads had been selected in Kyongbuk regions. The total of 13 road characteristic variables were evaluated by the discriminant analysis. The factors influencing the stability of forest road were bed rock, slope length, coverage, hardness, side-ditch erosion and road width. But aspect and soil texture were not significant for the stability in this area. In the correlation between forest environment and road structure, hardness and bed rock was highly significant in stability group, and coverage and side-ditch erosion was highly significant in instability group. 75 of 175 segments were instable whereas the others were stable. The centroids value by discriminant function in the stability and instability were estimated to 3.0585 and -1.9116, respectively. The stability criterion of forest road was discriminated from the centroids value of the each group. The main factors contributing the stability of forest road were significant in order of side-ditch erosion, coverage, soil texture, elevation, gradient, slope length and construction year. The prediction rate of discriminant function for stability evaluation of forest road was as high as 97.44%. In conclusion, the forest road structure factors such as length, coverage and slope gradient were controlled by construction techniques. If the factors like those should be considered in design, construction and forest road management, the stability of forest road may increase more. And also, it is necessary to take slope protection measures like small terraces and retaining walls for stability of cut slope.

• Journal of Korean Society on Water Environment
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• v.24 no.5
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• pp.618-625
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• 2008

Advanced Phase Isolation Ditch (APID) process was studied to develop economic retrofitting technology, for the plants where retrofitting of common activated sludge process is required. In this study, to evaluate the effluent BOD, SS, T-N, and T-P concentrations as process capable and stable parameters for treating municipal wastewater, a demonstration plant was installed and operated in the existing sewage treatment plant of P city. During this study, the average effluent BOD, SS, T-N, and T-P concentrations were 4.56, 5.20, 9.30, and 1.75 mg/L at the conventional mode and 3.95, 3.17, 7.65, and 1.18 mg/L at the modified mode. The modified mode (BOD: 3.69, SS: 3.19, T-N: 1.27, and T-P: 0.69) increased the process capability more than the conventional mode (BOD: 1.80, SS: 1.05, T-N: 2.17, and T-P: 0.15) in this study. If process capability over 1.0, this process is capable and stable to treat wastewater. Therefore, newly developed APID process with modified intermittent aeration mode can be one of the useful processes for stable organic matter and nutrients removal.

• Journal of Wetlands Research
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• v.1 no.1
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• pp.7-16
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• 1999

The objective of this study is to recover the contaminated ditch by using a biofilter filled up with waste-concrete media and vegetation bed. Two systems were tested for elimination of organic compounds, turbidity, nitrogen and phosphate. System 1 is three-stage system which consisted of one biofilter and two vegetation bed, system 2 has three-stage system consisted of one biofilter, one vegetation bed (four bed), and one media trench operated in series. In system 1, HRT of biofilter was 4 hour, and Oenanthe javanica was planted in two vegetation bed. In system 2, HRT of biofilter was varied 2 hours and Persicaria chinensis was planted on the top of the biofilter. And Oenanthe javanica, Hydrocharis asiatica, Salvinia natans were planted in four bed of a vegetation bed and the second vegetation bed of system 1 was rebuilt to a media trench bed. The elimination rate of BOD and turbidity was over 90% in both systems. The mean elimination rates 40~50%(system 1), 30~40%(system 2) for T-N and 40~50% (system 1), 30~40%(system 2)for T-P. T-N and T-P elimination performance of system 1 was a little higher(10%) than that of system 2. Results showed that vegetation bed are not efficient in reducing T-N and T-P. It was considered that HRT of vegetation bed of both systems was much lower(1~2hr) than that of conventional system(5~20days).

• Proceedings of the Korean Aquaculture Society Conference
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• 2005.05a
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• pp.90-91
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• 2005

• Journal of the Korean association of regional geographers
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• v.17 no.2
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• pp.141-149
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• 2011

The formation of Sajapyeong Alpine Wetland was influenced by factors of drainage basin and its geology, and fire-shifting cultivation. Sajapycong drainage basin had a narrow outlet, Sijeon-cheon in it flowed relatively slowly. Bedrock in basin was weak to mechanical weathering, many rock detritus were, produced. Deforestation for reclamation using fire accelerated topsoil loss. Thus much sediments was supplied to Sijeon-cheon and deposited in the channel bed, and wetland was formed on channel marginal footslope. In Sajapyeong moor were Gullies formed along road. Because they blocked sediments and throughflow transferring into moor, moor became dry land. In order to prevent this drying, we have, to raise water level of a drain ditch to level of weathered bedrock to transfer throughflow into moor, modify the shape of ditch to be naturally irregular, and construct large boulders step on the Sijeon-cheon bed to prevent from lowering of its bed.

• Journal of Korean Society on Water Environment
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• v.25 no.6
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• pp.872-878
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• 2009

Advanced Phase Isolation Ditch (APID) process was studied to develop economic retrofitting technology, for the plants where retrofitting of common activated sludge process is required. In this study, to develop and apply the modified intermittently aeration mode as process control conditions for treating municipal wastewater, a demonstration plant was installed and operated in the existing sewage treatment plant of P city. During this study, the average effluent $BOD_5$, SS, T-N, and T-P concentrations were 6.3, 4.5, 10.0, and 1.3 mg/L. The modified mode decreased the nitrification capability more than the conventional mode in the application period. Nitrate in the anaerobic condition can have a negative effect on biological phosphorus removal. In the decreasing nitrate levels, the modified mode increased the biological ability of removal phosphorus more than the conventional mode in this study. Therefore, newly developed APID process with modified intermittent aeration mode can be one of the useful processes for stable organic matter and nutrients removal.