• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.4
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• pp.136-145
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• 2011

For a massive project related to building national industrial complexes on a soft ground applied to PVD after dredging and hydraulic fill, laboratory tests were carried out using undisturbed sample taken from various depth. Piezocone penetration and dissipation tests were carried out to assess horizontal coefficient of consolidation and initial stress in field. The ground consists of upper dredged fill and lower original clay layer having both similar marine clays. It should be, however, considered as multi-layered soft ground having different initial void ratio, initial water content, initial effective stress, and permeability and compressibility with directions. To assess initial stress of those soft layers in which have different stress history related to consolidation, CPTu test results, especially excess pore water pressure, were analyzed. It allows to find out distribution of excess pore water pressure and initial stress inner original clay layer.

• Journal of the Korean Institute of Landscape Architecture
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• v.36 no.3
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• pp.21-28
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• 2008

The management of soil organic matter(SOM) is a key component of golf course green maintenance. As part of a major project examining the sustainable management of SOM on golf course greens, the SOM status of different age greens maintained in the same root zone composition and management were compared. Then the microbial activity, tiller number, bulk density, water content, pH, EC, and T-N in the soil were measured. In the 0${\sim}$5cm depth SOM accumulation showed no significant difference between greens. Below 5cm SOM showed a strong significance between greens and had a positive(+) correlation with year and negative(-) correlation with depth. when regression equations were used to predict SOM accumulation with year and depth, SOM below 5cm tended to increase with a rate of 0.061% . year$^{-1}$ and decrease with a rate of 0.079% . $cm^{-1}$(R2==0.841). Soil microbial activity was investigated with age and depth by using a dehydrogenase assay. Results showed a sharp drop with depth in all greens. The soil microbial activity below 5cm showed no difference between greens. The accumulated SOM below 5cm may be very resistant to decomposition in the long-term. Five years after establishment, the bulk density did not significantly change. The water content, EC, and T-N had a significant correlation with SOM. The pH decreased with the year, which may influence SOM accumulation. Organic matter accumulation was mainly affected by the pH decrase，low soil microbial activity, and high organic matter resistant to decomposition, but the effects of water content, EC, and T-N were obscure.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.3
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• pp.19-26
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• 2017

Concrete is a construction material with porous media and corroded steel inside affects negatively to durability and structural safety. This study aims a derivation of quantitative relationship between measured HCP (Half Cell Potential) and corrosion amount considering cover depth and W/C (water to cement) ratio. For the work, cement mortar specimens with 3 different W/C ratios and 4 different cover depths are prepared, HCPs are measured with 3 different corrosion level. HCP measurement significantly increases in the saturated condition and linear relationship is observed between corrosion level and acceleration period. With increasing corrosion level and W/C ratio, and decreasing cover depth, HCP measurement increases. Considering total corrosion level and HCP measurements, relatively low COV(Coefficient of Variation) of 0.67 is evaluated through multi-linear regression analysis, however higher COVs over 0.90 can be obtained considering level of HCP measurement. In the room condition, corrosion level can be evaluated through measured HCP in the given conditions of cover depth, W/C ratio. diameter of steel inside.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.1570-1576
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• 2008

Construction of the water-friendly facilities in the apartment complex and industrial complex became popular these days. In planning water-friendly facilities, kinds, layouts, water sources, water quality and water circulation system should be studies. In this study, several alternatives for a regional industrial complex project were studies and a most reasonal alternative was selected. A main canal across the central part of the complex is the principle facility with ponds and parks. The water source alternatives were a river nearby, a reservoir, ground water and urban water supply system. For each system, water quantity and quality, circulation system, permit and maintenance were compared. The facilities should be constructed with natural material such as rock and gravel. Average depth and velocity in the canal should be 10 cm and 0.15 m/s, respectively in order to people can feel the water flow in the canal. Based on the comparison, it is found that using the ground water, and water circulation system with storage tanks at the upper and lower ends of the canal system is the best alternative.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.7
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• pp.4977-4983
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• 2015

The full depth excavation induces couple of technical and social problems like increase of construction cost and time for excavation and backfill, increase of public complains and delay of traffic, and so force. In order to overcome these problems, lots of laboratory tests were carried out for sewer pipeline of maintenance materials with trenchless methods. The testing materials are PVC strip and then the lab tests were followed by Korean Standard. We will treat the structure safety and pipe integrity of PVC profile more excellent than the profile have application to SPR. There is no side-effect to process and to satisfy the criteria of tensile strength, impact strength and softening temperature. The profile with resin adhesive showed no leakage of water at specific pressure.

• Journal of the Korea institute for structural maintenance and inspection
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• v.10 no.3
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• pp.195-202
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• 2006

Deterioration of sewer concrete is representative that biochemical corrosion according to the $H_2S$ has growth by inhabit sulfur-oxidzing bacteria because of special environment in sewer. But in case of domestic, fundamentally, sulfur-oxidzing bacteria could moderate development of repair material method is need because of corrosion prevent method is inconsideration with carry out to improve project. In this paper, after development of spread type antibiotic with antibio-metal, antibacterial performance about sulfur-oxidzing bacteria of antibiotic and tested to estimate fundamental properties of bonding strength, abrasion contents, contents of water absorption, contents of air permeability, carbonation depth, chloride ion penetration depth and chemical resistance of spread with antibiotic restorative mortar.

• Journal of the Korea institute for structural maintenance and inspection
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• v.10 no.5
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• pp.163-170
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• 2006

Recently, piezocone penetration test is frequently used in order to estimate the characteristics of soft ground with standard penetration test, generally used in the past. In this study, the correlation of standard penetration test, piezocone penetration test and driving resistance of vertical drain is analyzed in order to increase the confidence for determination of soft ground depth. As the results of each zone, the relation between standard penetration test and piezocone penetration test shows qc=(1.09~1.63)N at the soft ground, determined by 5/30 N value which is decided for soft ground criteria. And qc=(1.21~1.98)N was shown at the point of compressible layer, evaluated by the preconsolidation pressure. And driving resistance of vertical drain is $65{\sim}70kgf/cm^2$ which is equal to $10kgf/cm^2$ of cone penetration resistance.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.1732-1736
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• 2008

The characteristics of a river flow analysis are significant for river maintenance plan. At the present time, HEC-RAS, 1-Dimensional Numerical Analysis Model, is mainly applied to analyze the character of a river flow. The shape of a river is somewhat in longitudinal linear form. It was suspected that the usage of 1-dimensional numerical analysis model is more economical. Development of numerical analysis models and computers are possible to calculate large volume. Hence, it is possible to adapt the analysis of the key stations by 2-dimensional numerical analysis model. The limitation of 1-Dimensional Numerical Analysis Model is that it is hard to evaluate structure affection of numerical simulation by energy loss coefficient at river structure analyzing. When adaptation of the 2-dimensional numerical analysis model in river structure ensues, it takes more objective analyzing than 1-dimensional numerical analysis model for flow affection by river structure. 2-dimensional numerical analysis model consults with the different structure position of hydraulic characteristics and different water depth of shape and scope in vertical flow. 1-dimensional numerical analysis model is possible to simulate with only energy loss coefficient for sudden river section changing, sudden waterway changing by curved. 2-dimensional numerical analysis model use original geographical features. So the model removes technical subjectivity of faulty judgment. It is an objective analysis.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.9
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• pp.817-824
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• 2009

To prevent turbidity breakthrough in a depth filter caused by hydraulic shock loads, influence of turbidity and particle number in filtrate by variation of operating filter number depending on inflow change was investigated. Inflow quantity at the S water treatment plant (WTP) was varied and ratio of maximum/minimum inflow quantity was 2.2, therefore filtration velocity was also subsequently changed. The S WTP changed operating filter number depending on inflow variation to minimize change of filtration velocity. Particle breakthrough was not severe when operation system was changed, out-of-operation and re-start of filter was repeated depending on inflow quantity. Slight particle breakthrough was noticed when re-start of filter was implemented at the filter that had a cumulative filtration run time of less than 10 h or more than 50 h. This can be attributed to the inadequate ripening and over accumulation of particles on media. Therefore, it is more efficient to choose a re-starting filter basin which has cumulative filtration run time more than 10 h or less than 50 h to reduce particle breakthrough. Filter number variation depending on inflow change was proven to be a method for improvement of unit filter run volume (UFRV).

• Journal of the Korean Institute of Landscape Architecture
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• v.33 no.6 s.113
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• pp.51-77
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• 2006

Pond management is a critical part of overall golf course management, both during growth and maintenance modes of turf care. This study investigated 48 ponds in nine 18- or 27-hole golf courses to analyze the environmental characteristics of ponds. The research process had three phases: (1) inventory and analysis of grading plans and drainage plans, (2) field verification and interviews with greenskeepers, and (3) analyses of water quality and statistics. All data were collected from May to August in 2004. The results of this study can be summarized as follows: 1. It is desirable to site a golf course in a small watershed with high watershed eccentricity to control storm water runoff efficiently and to minimize soil erosion during construction. 2. The siting and size of a pond should be determined through a land-use analysis of the watershed for the purpose of ecological management. The bigger the forest-to-golf course ratio, the better the water quality will be. 3. The size and capacity of each individual ponds varied and there were many somewhat longish rather than round ponds. 4. There were many differences among golf courses in naturalness of the ponds, and the correlation between naturalness and area of aquatic plants was very high. 5. Analyses of pond water quality indicated that the degrees of Dissolved Oxygen, Chemical Oxygen Demanded and Suspended Solids were relatively low values but Total Phosphorus and Total Nitrogen were too high. Therefore a systematic approach is needed to solve e problem. Pesticide residues were not detected in all ponds. 6. Water depth and area of hydrophyte should be considered when designing an ecological pond. 7. All ponds used storm water as a main source of water supply and added underground water. Aquatic plants and physical methods such as water aeration and spray fountains were the main choices for maintaining a healthy aquatic environment.