• Journal of the Korea Organic Resources Recycling Association
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• v.11 no.4
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• pp.57-65
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• 2003

Livestock farming is one of several industries that have faced criticism because of its impact on the water quality, soil contamination and air pollution. The livestock feces can cause some environmental problems. The best way to treat the feces is to recycle the manure as an organic fertilizer after fermentation or composting. This study was carried out to investigate the characteristics of composting of manure in several composting conditions. The variations of physicochemical characteristics of each compost piles containing different level of air volume were analyzed throughout the composting period. In this study, pigs manure compost piles mixed with saw dust were composted in 110L of laboratory scale plastic vessels and $1.5m^3$ of small cubic wooden composting vessels for 60days. The compost piles were ventilated continuously with air pump throughout the composting duration. The air volume ventilated into the piles was regulated by chock valve attached to the inlet pipe. The ventilation level was adjusted by 20, 50, 100, 150 and $200L/m^3/mim$, respectively. The highest temperature of the compost increased to $72^{\circ}C$ during composting period. After 20days from beginning of fermentation, concentrations of $H_2S$, $CH_3SH$, DMS and DMDS generated from compost piles were 29, 16, 6 and 5ppb in blow in state compost pile, conversely, in blow out state compost pile, the parameters were 32, 24, 15 and 14ppb, respectively.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.24 no.2
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• pp.128-137
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• 2012

This paper deals with the local scour around a pipeline exposed to combined waves and current in the shallow water zone. To investigate the characteristics of the scour around a pipeline on the sea bed, experiments were performed according to the various pipe diameters, wave periods, wave heights, and current velocities. Wave generator and current generator were used for the experiments. Two current directions were used ; co-direction and counter direction to the waves. With the experimental results, the correlations between the scour depths and non-dimensional parameters such as Keulegan-Carpenter number(KC), Froude number(Fr), Ursell number(Ur) and velocity ratio were analysed. The relative scour depths were found obviously to be dominated by the wave component when the velocity ratio function approaches zero and those are gorverned by the current component when the velocity ratio approaches unity. Velocity ratio function was approved to be a proper parameter which is able to express the change of the scour in the combined wave and current zone. Also considering the orbital velocity and the current velocity into Fr numer and KC number respectively, scour depths show more favorable correlationship with the parameters.

• Journal of Environmental Impact Assessment
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• v.29 no.3
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• pp.219-229
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• 2020

This study evaluated the applicability of the convergence technology by deriving the optimum conditions about operating factors of electrical resistance heating to enhance the soil flushing effect on soil contaminated with bunker C oil in the coastal landfill area. As a result of the batch scale experiment, the flushing efficiency of the VG-2020 was higherthan that of the Tween-80, and the flushing efficiency increased by about 1.4 times at 60℃ compared to room temperature. As a result of the electrical resistance heating box experiment, soil temperature rose to 100℃ in about 40~80 minutes in soil with water content of 20~40%, and it was found that the heat transfer efficiency is excellent when the pipe-shaped electrode rod with STS 316 material is located in a triangular arrangement in saturated soil. In addition, it was confirmed that the interval between the electrode rods to maintain the soil temperature above 60℃ under the optimum conditions was 1.5 m, and the soil flushing box experiment accompanying electrical resistance heating showed TPH reduction efficiency of about 55% at 5 Pore Volume, and satisfied the Korean standard for the conservation of soil (less than TPH 2,000 mg/kg) at 10 Pore Volume.

• Journal of Korean Society for Geospatial Information Science
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• v.15 no.3
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• pp.19-26
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• 2007

The renewal update of the digital map constructed through NGIS has been conducted for the enhancement of usage, maintenance so that the latest data is guaranteed. The total update has been done every five years for five regions of the country using aerial photographs and satellite images. By launching the third phase of NGIS, the updating plan was changed from total to total or partial update including the real time update scheme. Furthermore, the update period was improved from five to two years and four years for a large and a small city, respectively. Therefore, it is necessary to develope a matching technique which combines various geographic information (such as drawing map, surveying drawing and map) with exact position on the digital map. In this study, we developed a matching algorithm based on central point and suggested a method which uses general surveying drawing for revision/update of the digital map. The general survey is conducted when a civilian development on lands are approved. Thus, the outcome from the survey, which is the general survey drawing, contains the latest various contents such as road, building, water pipe and manhole. A consistent and efficient method using the general survey drawing for near real time update of the digital map by applying the developed matching algorithm is presented.

• Journal of Digital Convergence
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• v.14 no.11
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• pp.257-265
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• 2016

The purpose of this study was to develop a strainer that could protect a flow system by blocking the introduction of foreign substances into the pipe of industrial or architectural facilities. Strainers are installed at the front tip of valves, machines, or pumps in the piping line of clean water, oil, or gas. There are Y-type, U-type, and T-type strainers. The study identified problems with the Y-type strainers, develop a "C-type strainer with its inlet and outlet on a straight line" as a more improved new model, and compared them in functions in a full-scale strainer test. The study conducted a full-scale strainer test according to four situations at the flow laboratory of Korea Research Institute of Standards and Science by using the old Y-type strainer and C-type strainer 50A. The test results show that the C-type strainer had a higher capacity coefficient(Kv) than the Y-type one, recording 74.9% when there was no screen, 54.5% when there were no foreign substances in the screen, 54.2% when there was a 15% accumulation of foreign substances, and 52.4% when there was a 30% accumulation of foreign substances. The investigator conducted a test only with the 50A type due to the limitations of life-size strainers, but the results demonstrate that the C-type strainer had better flow characteristics than the Y-type one.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.10
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• pp.901-908
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• 2009

We examine the processing method of the food wastewater to direct spray at living waste incinerator. The demoscale stoker system is used as a incineration facility. The results show that it brings effect on the reduction of nitrogen oxide ($NO_x$) concentration as well as the ammonia ($NH_3$) amount in SNCR (selective non-catalytic reduction) by the incineration of food wastewater which is containing a plentiful ammoniac nitrogen ($NH_3$-N). Furthermore, the stability of incineration facility and the extension of operation period is actualized as a improvement of clogging phenomenon on outer wall of water pipe as the 870~$950^{\circ}C$ maintain of exit temperature in a second combustor by spray of the food wastewater. The 26 items of air pollution matter of nitrogen oxide ($NO_x$), sulfur oxide ($SO_x$) and dioxin etc. are measured. The results show that it is under the value of allowable exhaust standard.

• Proceedings of the KSR Conference
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• 2003.10c
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• pp.287-294
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• 2003

There are a lot of curved subway stations in Seoul metropolitan area. These must be straightly constructed as many as possible. But some of stations are roundly designed and built in order to avoid pre-existed underground obstacle such as basement of high rise building, underground gas or water pipe line and subway stations from another line. As shown fig 1, one of the biggest problem occurring curved subway station is considered large gap between platform and vehicle when vehicle completely stop at the station. The gap potentially is in existence to subway passenger as very dangerous factors in rush hours. If passenger accidentally drop their food or leg between this gap when they get on the train and train leaves station, the passenger will be seriously injured by vehicle. In this paper, various design and instruments are introduced and best solution for this matter will be presented. In order to eliminate any possibility of accident happened gap between platform and vehicle, KRRI(Korea Railroad Research Institute) have been developed new safety instrument. These technologies were applied for patent by KRRI. These mechanisms will provide confidence as well as safety to Korean subway passenger

• Journal of the Korean Society of Hazard Mitigation
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• v.11 no.3
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• pp.143-150
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• 2011

Energy loss at manholes, often exceeding friction loss of pipes under surcharged flow, is considered as one of the major causes of inundation in urban area. Therefore, it is important to analyze the head losses at manholes, especially in case of surcharged flow. The stream characteristics were analyzed and head loss coefficients were estimated by using the computational fluid dynamics(CFD) model, FLUENT 6.3, at surcharged square manhole in this study. The CFD model was carefully assessed by comparing simulated results with the experimental ones. The study results indicate that there was good agreement between simulation model and experiment. The CFD model was proved to be capable of estimating the head loss coefficients at surcharged manholes. The head loss coefficients with variation of the ratio of manhole width(B) to inflow pipe diameter(d) and variation of the drop height at surcharged square manhole with a straight-path through were calculated using FLUENT 6.3. As the ratio of B/d increases, head loss coefficient increases. The depth and head loss coefficient at manhole were gradually increased when the drop height was more than 5cm. Therefore, the CFD model(Fluent 6.3) might be used as a tool to simulate the water depth, energy losses, and velocity distribution at surcharged square manhole.

• Journal of Korean Tunnelling and Underground Space Association
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• v.24 no.6
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• pp.599-615
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• 2022

In order to excavate underground tunnel most safely such as Han river, the slurry shield TBM method is applied to cope with face of high water pressure for many metro projects. In downtown subway project most of excavated soil is discharged externally whereas in road construction excavated soil is used as filling materials so it becomes important factor for success of the project. After excavated soil, weathered rock and soft rock are discharged with bentonite through discharge pipe to slurry treatment plant then those soils are separated in separation plant according to those size. Fine grained soil has been discarded together with filter cake but it is not toxic and can be mixed with coarse aggregate in proper ratio so this study is performed to find use of qualified filling material to meet quality standard. Therefore, in this study, legal standards and quality standards for the utilization of excavated soil of the slurry shield TBM method were examined and test was conducted to derive recycling way for filter cake and aggregate. And a plan for using it as a filling material for road construction was derived. Because bentonite is a clay composed of montmorillonite, and the excavated soil in the tunnel is also non-toxic, disposal of this material can waste social cost so it is expected to be helpful in the underground space development project that carries out the TBM project by recycling it as a valuable resource.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.6
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• pp.822-831
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• 2021

Although programs have been developed to evaluate the risk of dragging anchors, it is practically difficult for VTS(vessel traffic service) operators to calculate and evaluate these risks by obtaining input factors from anchored ships. Therefore, in this study, the gross tonnage (GT) that could be easily obtained from the ship by the VTS operators was set as an independent variable, and linear and nonlinear regression analyses were performed using the input factors as the dependent variables. From comparing the fit of the polynomial model (linear) and power series model (nonlinear), the power series model was evaluated to be more suitable for all input factors in the case of container ships and bulk carriers. However, in the case of tanker ships, the power supply model was suitable for the LBP(length between perpendiculars), width, and draft, and the polynomial model was evaluated to be more suitable for the front wind pressure area, weight of the anchor, equipment number, and height of the hawse pipe from the bottom of the ship. In addition, all other dependent variables, except for the front wind pressure area factor of the tanker ship, showed high degrees of fit with a coefficient of determination (R-squared value) of 0.7 or more. Therefore, among the input factors of the dragging anchor risk assessment program, all factors except the external force, seabed quality, water depth, and amount of anchor chain let out are automatically applied by the regression analysis model formula when only the GT of the ship is provided.