• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.1
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• pp.85-91
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• 2021

Aggregate waste separator with rotating separating net was designed for applying classification process of construction waste. In order to evaluate the performance of the aggregate waste separator, according to the type of waste, standardized waste samples are prepared using acrylic. The appropriate operating point was evaluated by the classification efficiency and misclassification rate of recycled aggregate according to the control frequency of the blower operating and inlet position of the separating net. The classification efficiency at the operating point of the aggregate waste separator was evaluated through flow analysis assuming recycled aggregate and waste sample as particles. As a result of the performance test, when the distance. between the conveyor belt and the inlet was 0.2m, the classification efficiency was 95%, but the misclassification rate of recycled aggregate was 2% or more, which satisfies the classification efficiency and the misclassification rate of less than 2%. The operating point was shown at a control frequency of 58Hz at a suction distance of 0.254m. As a resu lt of flow analysis, there was no misclassification of recycled aggregate. In order to redu ce constru ction waste in the existing recycled aggregate production process, adsorption system using a rotating separating net that can be operated as an installation type was built.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.6
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• pp.906-917
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• 2022

This study aimed to compare differences according to categories of fishery and marine environmental policies for the (estimated) amount of fishery waste generated by fishing, and to analyze the correlation between associated independent and dependent variables. The independent variables were divided into three dif erent sectors. The first sector included precautionary policies that observed eco-friendly fishing support program, institutional prevention activities, and physical barriers installation. The second sector with the current management policies included the relevant vessel operations, establishment of fishery order, fishery restructuring, and fishery ground clean-up. Thirdly, post-response policies comprised the litter purification from river to shoreline, the collection and removal of marine, sedimentary, and floating debris, purchasing salvaged debris generated while fishing, fishery waste disposal, and repairing damage caused by marine litter. The indicator used was the settlement amount by each program. The dependent variable was the estimated amount of fishery waste and the indicator was the sum of the loss of traps and gill nets and the loss of their appendages. According to the results of Kruskal-Wallis Test, the estimated amount of fishery waste was highest in the East Sea in terms of sea area and the highest in the Si(city) according to basic local municipality. The settlement amount related to the marine environment services was largest in the Gun(county). Further, there were significant differences between Gun(county) and the other regions(Si(city) and Gu(autonomous district)) with respect to most variables. The variables related to the estimated amount of fishery debris were the project purchasing salvaged debris generated while fishing and fishery waste disposal program in the post-response policies.

• Journal of Environmental Impact Assessment
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• v.31 no.1
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• pp.75-81
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• 2022

The purpose of this study is to propose the angle-limit of the escape ramp by analyzing the frog behavior characteristics according to the inclination angle of the waterway escape ramp installed in the concrete U-bench plume pipe channel. Forthe experiment, an escape test device was manufactured with the same shape and number of materials applied in the field. And Rana coreana living in paddy wetlands were sel selected. The main behaviors of frogs on the slope were 'jumping', 'crawling' and 'slipping', and afterrecording the behavioralresults according to the inclination angle, statistical analysis was conducted using the chi-square test method. As a result of the analysis, there was no statistically significant difference between 30° and 40°. This result is an evidence for expanding the standard of inclination angle 30° suggested in the 'Guidelines for Installation and Management of Ecological Pathways' to a maximum of 40°. However, further research is required in that the escape ramp targets not only Korean frogs but also various small wild animals. However, considering that various wild animals are affected by artificial canals, additional studies using various target wild animals are needed.

• Journal of the Korean Geotechnical Society
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• v.23 no.4
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• pp.161-167
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• 2007

In this study, ultimate lateral load capacity of piles is analyzed with consideration of lateral stress effect. Based on results obtained in this study, a method for the estimation of ultimate lateral load capacity is proposed. This makes it possible to more realistically estimate the ultimate lateral load capacity under various stress states caused by in-situ soil condition and pile installation process. Calibration chamber test results with various soil conditions were used in the analysis. From the test results, it was found that effect of the lateral stress was greater than that of the vertical stress on the ultimate lateral load capacity of piles. It was also found that, as the relative density increases, displacements required to reach the ultimate state increases, showing relative displacements of around 14% and 18-25% for $D_R$ : 55% and 86%, respectively. Based on results obtained in this study, a methodology for the estimation of ultimate lateral load capacity of piles using correction factors was proposed. Results from proposed method matched well measured results.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2021.11a
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• pp.127-128
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• 2021

This study suggests surface wave communication, which uses a metal surface as a medium, to provide wireless communication in the extreme environment due to surrounding metal materials on vessels. The test was conducted on a G/T 265 tons tug boat, and to confirm the possibility of surface wave communication between a bridge and each designated space in the boat. As a result, the transmission speed was 13Mbps in average. For the test case between the bridge and the engine room, transmission speed was 4.3Mbps while the engine was on, and 1.2Mbps during sailing. It was able to be overcome by partially changing the equipment installation location. Surface wave communication in a bow storage, a fully enclosed space, had 8Mbps better transmission speed than wireless communication; this confirmed the superiority of surface wave communication in confined spaces on a vessel. Additional surface wave generators were designed and applied to resolve the paint issue. It is expected to apply surface wave communication to implement the new wireless solution on vessels.

• Journal of Environmental Impact Assessment
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• v.33 no.2
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• pp.64-73
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• 2024

As the seriousness of habitat destruction caused by development projects emerges, the importance of environmental impact assessment (EIA) is increasing to preserve biodiversity. In previous studies, research is being conducted to quantitatively evaluate the biodiversity impact of development factors and surrounding environmental factors on the landscape scale, but research on the factors affecting the reduction of biodiversity based on development projects is insufficient. This study examined whether independent variables (size of development project, type of the development, DEM, ecosystem and nature map, distance from the green land, distance from the protected area), which have been proven to effect biodiversity through the previous researches, have a significant effect on the change of richness index (RI) through multi-class logistic regression analysis, T-test, and analysis of the development type. As a result, only the size of development project and the first richness index in EIA showed p-value less than 0.05. And it was confirmed that the reduction in biodiversity was significantly changed in the following construction types: installation of sports facilities, energy development, and development of industrial location and industrial complex. Since the results of this study confirmed that the impact of the variables may be inconsistent depending on the analysis scale, additional study of necessary indicators at the development project is needed to analyze biodiversity changes in EIA accurately.

• Tunnel and Underground Space
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• v.30 no.4
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• pp.359-381
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• 2020

Within the framework of DECOVALEX-2019 Task D, full-scale engineered barriers experiment (FEBEX) at Grimsel Test Site was numerically simulated to investigate an applicability of implemented Barcelona basic model (BBM) into TOUGH2-MP/FLAC3D simulator, which was developed for the prediction of the coupled thermo-hydro-mechanical behavior of bentonite buffer. And the calculated heater power, temperature, relative humidity, total stress, saturation, water content and dry density were compared with in situ data monitored in the various sections. In general, the calculated heater power and temperature provided a fairly good agreement with experimental observations, however, the difference between power of heater #1 and that of heater #2 could not captured in the numerical analysis. It is necessary to consider lamprophyre with low thermal conductivity around heater #1 and non-simplified installation progresses of bentonite blocks in the tunnel for better modeling results. The evolutions and distributions of relative humidity were well reproduced, but hydraulic model needs to be modified because the re-saturation process was relatively fast near the heaters. In case of stress evolutions due to the thermal and hydraulic expansions, the computed stress was in good agreement with the data. But, the stress is slightly higher than the measured in situ data at the early stage of the operation, because gap between rock mass and bentonite blocks have not been considered in the numerical simulations. The calculated distribution of saturation, water content, and dry density along the radial distance showed good agreement with the observations after the first and final dismantling. The calculated dry density near the center of the FEBEX tunnel and heaters were overestimated compared with the observations. As a result, the saturation and water content were underestimated with the measurements. Therefore, numerical model of permeability is needed to modify for the production of better numerical results. It will be possible to produce the better analysis results and more realistically predict the coupled THM behavior in the bentonite blocks by performing the additional studies and modifying the numerical model based on the results of this study.

• Archives of design research
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• v.18 no.2 s.60
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• pp.155-164
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• 2005

Home-service robots need to have sufficient spatial information about the surroundings for interacting with human intelligently and performing services efficiently. It is very important to investigate the efficient interaction style that supports map building task through human-robot collaboration. We first analyzed map building task with a cleaning robot and drew 4 design factors and tentative solutions, including map building procedure (task-preferred procedure/space- preferred procedure), LCD display installation (robot/robot+remote control), navigation method (push type/pull type), feedback modality(GUI/GUI+TTS). The design factors and tentative solutions were defined as independent variables and levels. This research investigated how those variables affect to the human task performance and behavior in map building tast. 8 kinds of experiment prototypes were built and usability test among 16 house wives was conducted for acquiring empirical data. As the experiment result, in terms of map building procedure, space-preferred procedure indicated better task performance than task-proffered procedure as we expected. For the LCD display installation factor, remote control with LCD display indicated higher task performance and subjective satisfaction. In robot navigation method, it was very difficult to find a significant difference between push type and pull type which contrary to our expectation. In fact, push type indicated higher subjective satisfaction. Also in feedback modality, we have acquired negative feedback an additional TTS operation guidance. It seems that robot's autonomy before achieving spatial information is rudiment condition which means users are just interacting with a mobile appliance. Thus they prefer remote-control-based interaction style in robot map building process as they used in traditional appliance control.

• Journal of Korean Society of Transportation
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• v.35 no.4
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• pp.261-277
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• 2017

This study defines influencing sections as the part of the road section where passing vehicles are traveling with the lower speed compared to speed limit due to speed humps. The influencing section was divided into 3 parts; influencing section before the speed hump, interval section, and influencing section after the speed hump. This analysis focused on the changes of each part depending on installation types, vehicle types, and daytime or nighttime. For the interval section, especially, the ratio of distance traveled with lower speed than speed limit to interval section is defined as effective influencing section ratio to be analyzed. Vehicle speed profiles were collected with a speed gun to extract influencing section lengths. The survival analysis was applied and estimated survival functions are compared with each other by several statistical tests. As a consequence, the average length of influencing section on the 50m sequential speed humps was 75.3% longer during the deceleration than that of isolated speed hump, and 18.9% during the acceleration. The effective influencing section ratio for the 30m and 50m sequential speed humps had a small difference of 81.0% and 76.0% while the absolute values of the section that passing speed were less than the speed limit were longer on 50m sequential speed humps, each being 24.3m and 38.0m. Using the log rank test, it was evident that sequential speed humps were more effective to increase the length of influencing sections compared to the isolated speed hump. Vehicle type was the strong factor for influencing section length on the isolated speed hump, but daytime or nighttime was not the effective one. This research result can be used for improving the efficiency selecting the installation point of speed humps for road safety and estimating the standard of the distance between sequential speed humps.

• Economic and Environmental Geology
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• v.49 no.6
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• pp.445-458
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• 2016

Most of water curtain cultivation (WCC) area in Korea has been inveterately suffering from the gradual draw-down of groundwater level and related shortage of water resources at the late stage of WCC peak time. To solve this problem, artificial recharge techniques has been recently applied to some WCC area. This study introduces infiltration gallery, which is one of the artificial recharge methods, and tentatively examined the effectiveness of three galleries installed at Sangdae-ri WCC area of Cheongju City. Seven galleries are set up at each empty space between eight vinyl houses in this area and its dimension is designed as 50 cm in each width and height and 300 cm in each length. Installation process was including bed excavation, backfill with gravels and silica sands, and completion of gallery by equipment of piezometer and covering with non-woven cloth. For each B, C, D gallery, 3 types of test including preliminary, four step and one long-term injection were performed. The first preliminary test showed the rough relations between injection rates and water level rise as follows; 20 cm and 30 cm level rise for $33.29{\sim}33.84m^3/d$ and $45.60{\sim}46.99m^3/d$ in B gallery; 0 cm, 16 cm and 33 cm level rise for $21.1m^3/d$, $33.98m^3/d$ and $41.69m^3/d$ in C gallery; 29 cm and 42 cm level rise for $48.10m^3/d$ and $52.23m^3/d$ in D gallery. Afterwards, more quantitative results estimating effectiveness of artificial recharge were reasoned out through stepped and long-term injection tests, which is expected to be employed for estimating water quantity re-injected into the aquifer through these galleries by natural injection over the period of WCC peak time.