• Korean Journal of Soil Science and Fertilizer
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• v.40 no.1
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• pp.12-17
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• 2007

This study was conducted to evaluate the characteristics of nonpoint source pollutants discharge from a small rural watershed. A typical rural area in Gongju City, Korea, was selected as the research site. Water quality and quantity in streams and rainfall samples were analyzed periodically from May to October 2005. Pollutant loads were estimated from a nonpoint source pollution model (AvSWAT, Arcview Soil and Water Assessment Tool). During the rainy season, from June 26 to 30 September 2005 and the dry season, before 26 June and after 30 September 2005, biological oxygen demands and chemical oxygen demands accounted for 91.3% and 93.7% of annual load, respectively, while total-N and total-P were 97.1% and 91.1% of annual load, respectively. The observed stream flow was $66.5m^3sec^{-1}$, while simulation stream flow was $66.2m^3sec^{-1}$. That can be assumed that simulation can be used to estimate the stream flow without practical measurement. However, the runoff trend following the occurrence of a storm event was not recorded properly.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.41 no.2
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• pp.161-172
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• 2021

Along with the emergence of technologies related to the 4th industrial revolution, all industry sectors are making efforts to dramatically increase productivity by actively introducing high-tech technologies. Recently, the MLIT (Ministry of Land, Infrastructure and Transport) is trying to solve problems related to low productivity and high accident rate in the construction industry by applying the 4th industrial revolution technologies to infrastructure construction through smart construction R&D projects. This research was performed as part of the smart construction R&D project supported by MLIT, and the purpose is to develop a module that automatically generates moving paths for construction equipment based on the earthwork plan for road construction. The generated moving path can be used to provide safe and efficient paths for construction equipment and to support MC and MG to work efficiently. The moving paths for construction equipment are created based on the Visibility Graph and a case study is performed to show how the paths are generated based on a given construction site.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.4
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• pp.321-330
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• 2021

By reviewing domestic and international papers, this study examines various fields in which drones are used, and based on the results, fields are suggested in which drones can be used for the work of firefighters. Overall, the research results show that drones are most commonly used for search (51%), disaster and fire monitoring (35%), and delivery (14%). Specifically, in the search field, using a drone is more efficient in terms of manpower, equipment, time, and cost than using people, which is the current practice. Secondly, in disaster and fire monitoring, drones can analyze and identify disasters and fire sites in real time. Therefore, it was confirmed that the use of drones is helpful in securing the safety of firefighters and identifying a disaster site. Third, research in logistics shows that drones can secure the so-called golden time in emergency situations by delivering rescue and relief supplies, emergency medicine, and blood in short order. In a rapidly changing disaster environment, and considering aging in firefighters, this study is meaningful in that it promotes drone utilization in the firefighting field by investigating basic data on drone utilization plans.

• Korean Journal of Environment and Ecology
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• v.33 no.1
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• pp.52-63
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• 2019

This study analyzed the characteristics of vegetation structure of the camphor tree (Cinnamomum japonicum) community in the area of mount Tachibana, Kasuya county, Fukuoka Prefecture designated as a special natural monument in Japan. The survey showed overwhelming dominance of canopy tree in the canopy layer (about 30 m in tree heights and 92.79 cm in average breast height diameter) but no appearance in the understory layer or the shrub layer. In the understory layer and the shrub layer, Castanopsis sieboldii, Machilus thunbergii, Neolitsea sericea, and Cinnamomum yabunikkei, which were the competing species to the canopy layer and the late-successional species in the warm temperate climate zone, were mainly distributed. Moreover, the species diversity was generally low, indicating the vegetation characteristics that was not typical of evergreen broad-leaved forests. This is presumably because camphor trees were actively planted, protected, and cultivated to produce camphor which was valuable in the past. Although this site has not been artificially managed for the past 90 years as the raw materials of camphor have not been collected, vegetation transition did not proceed, which is unique. It is probably due to the fact that camphor was overwhelmingly dominant in the canopy layer so that the inflows of species were restricted, and young tree germination did not occur due to the allelopathy effects of camphor trees.

• Explosives and Blasting
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• v.37 no.2
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• pp.22-30
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• 2019

On sites where explosives are used, the effects of noise and vibration produced by the blast wave are subject to a number of operational restrictions. Recently, the number of civil complaints has increased and the standard of environmental regulations on secure goods has been greatly tighten. Therefore, work is generally carried out by machine excavation in case of close proximity of safety thing. Machine excavation methods have the advantage as reducing noise and vibration compared to blasting methods, but depending on the conditions of rock intended to be excavated, they are sometimes less constructive than planned. In general, the closer a rock type is to hard rock, the less constructible it becomes. In this paper, we are going to explain the construction of a construction section with a close proximity to a safety thing using electronic detonators. While the project site was designed with a machine excavation methods due to the close(9.9m) proximity of safety thing(the railroad), construction using electronic detonators was reviewed as an alternative method for improving rate of advance time and construction efficiency when expose to hard rock. Through blasting using electronic detonators, construction and economic efficiency were maximized while minimizing impact on surrounding safety things. Because $HiTRONIC^{TM}$, which is produced by Hanwha, has innovative stability and high explosion reliability, it is able to explode with high-precision accuracy. Electronic detonators are widely used in construction sites of railway or highway, other urban burrowing areas and large limestone mines.

• Journal of Korean Tunnelling and Underground Space Association
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• v.21 no.4
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• pp.573-585
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• 2019

The objective of this study is to propose the drainage system that has been improved the workability, waterproofing and drainage performance to treat the leakage from the cement concrete structures in underground. It is improved that the pipe for conveying ground leak in the existing drainage system had the problem in workability and waterproof. The drainage systems with the improved pipe for conveying ground leak were constructed in conventional concrete lining tunnels to evaluate the workability, waterproofing and drainage. The waterproof and the drainage performance of the drainage system was evaluated by injecting 1,000 ml of red water in the back of the drainage system at 3 weeks, 6 weeks, 9 weeks, 11 weeks, 14 weeks, 17 weeks and 23 weeks. During 6 months of field performance test, the average daily temperature of the tunnel site was measured from $-12.4^{\circ}C$ to $19.7^{\circ}C$. The daily minimum temperature was $-17.2^{\circ}C$ and the daily maximum temperature was $26.7^{\circ}C$. There was no problem in waterproof and drainage performance on the pipe for conveying ground leak and the drainage system during 6 months for field performance test. It is concluded that the improved drainage system can be applied to various cement concrete underground structures where leakage occurs, and has little seasonal effect.

• Journal of Environmental Science International
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• v.27 no.11
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• pp.1029-1048
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• 2018

In this study, seasonal Mann - Kendall test method was applied to 12 stations of the water quality measurement network of Nam-River based on data of BOD, COD, TN and TP for 11 years from January 2005 to December 2015 The changes of water quality at each station were examined through linear trends and the tendency of water quality change during the study period was analyzed by applying the locally weighted scatter plot smoother (LOWESS) method. In addition, spatial trends of the whole Nam-River were examined by items. The flow-adjusted seasonal Kendall test was performed to remove the flow at the water quality measurement station. As a result, BOD, COD concentration showed "no trand" and TN and TP concentration showed "down trand" in regional Kendall test throughout the study period. BOD and TP concentration in "no trand", COD, and TN concentration showed an "up trand" tendency in Nam-River dam. LOWESS analysis showed no significant water quality change in most of the analysis items and stations, but water quality fluctuation characteristics were shown at some stations such as NR1 (Kyungho-River 1), NR2 (Kyungho-River 2), NR3 (Nam-River), NR6 (Nam-River 2A). In addition, the flow-adjusted seasonal Kendall results showed that the BOD concentration was "up trand" due to the flow at the NR3 (Nam-River) station. The COD concentration was "up trand" due to the flow at NR1 (Kyungho-River 1) and NR2 (Kyungho-River 2) located upstream of the Nam-River. The effect of influent flow on water quality varies according to each site and analysis item. Therefore, for the effective water quality management in the Nam-River, it is necessary to take measures to improve the water quality at the point where the water quality is continuously "up trand" during the study period.

• Journal of Climate Change Research
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• v.8 no.3
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• pp.257-264
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• 2017

Carbon capture and storage (CCS) technology has been suggested as an ultimate strategy for mitigating climate change. However, potential leakage of $CO_2$ from the CCS facilities could lead to serious damage to environment. Plants can be a bio-indicator for $CO_2$ leakage as a cost-effective way, although plants' responses vary with plant species. In this study, a greenhouse experiment was conducted to investigate the relation between the $CO_2$ tolerance of corn species and the initial physiological responses to the elevated soil $CO_2$ concentration. Treatment groups included CI (99.99% $CO_2$ gas injection) and BI (no gas injection). Mean soil $CO_2$ concentration for the CI treatment was 19.5~39.4%, and mean $O_2$ concentration was 6.6~18.4%. The soil gas concentrations in the BI treatment were at the ambient levels. In the CI treatment, chlorophyll content was not decreased until the $13^{th}$ day of the $CO_2$ injection. On the $15^{th}$ day, leaf starch content and stomatal conductance were increased by 89% and 25% in the CI treatment compared to the BI treatment, respectively. This might be due to the compensatory reaction of corn to avoid high soil $CO_2$ stress. However, the prolonged $CO_2$ injection decreased chlorophyll content after 13 days. After $CO_2$ injection, plant biomass was reduced by 25% in the CI treatment compared to the BI treatment. Due to the inhibited root growth, leaf phosphorous and potassium contents were decreased by 54% on average in the CI treatment. This study indicates that corn has a high tolerance to soil $CO_2$ concentration of 30% for 2 weeks by its compensatory reactions such as an maintenance of chlorophyll content and an increase in stomatal conductance.

• Journal of the Korean Society of Mineral and Energy Resources Engineers
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• v.55 no.6
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• pp.588-595
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• 2018

This study has focused on evaluation of heavy metal contamination in seepage from 23 mine waste dumping sites in Korea. Seepage samples from the sites were taken and analyzed for heavy metals. The maximum levels (mg/L) in the samples were Al 53.98, As 16.19, Cd 1.15 Cu 37.30, Fe 28.64, Mn 39.00, Ni 0.097, Pb 0.750, and Zn 80.18. Among the sites, six mines were selected as continuous monitoring sites. As results of three months' monitoring of the sites, over the water guidelines for As, Cd, Cu, Fe, Mn, Zn and Al in seepage samples were found at two abandoned Au-Ag mines, Cd, Mn, Zn and Al at two Pb-Zn mines, and As, Fe and Mn at two other Fe-W mines. Therefore, those six mines need continuous monitoring on contamination assessment of seepage due to mining activities.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.3
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• pp.16-22
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• 2019

Off-line programming and robot calibration through simulation are essential when setting up a robot in a robot automation production line. In this study, we developed a new robot calibration method to match the CAD data of the production line with the measurement data on the site using 3D scanner. The proposed method calibrates the robot using 3D point cloud data through Iterative Closest Point algorithm. Registration is performed in three steps. First, vertices connected by three planes are extracted from CAD data as feature points for registration. Three planes are reconstructed from the scan point data located around the extracted feature points to generate corresponding feature points. Finally, the transformation matrix is calculated by minimizing the distance between the feature points extracted through the ICP algorithm. As a result of applying the software to the automobile welding robot installation, the proposed method can calibrate the required accuracy to within 1.5mm and effectively shorten the set-up time, which took 5 hours per robot unit, to within 40 minutes. By using the developed system, it is possible to shorten the OLP working time of the car body assembly line, shorten the precision teaching time of the robot, improve the quality of the produced product and minimize the defect rate.