• Journal of the Korean Society of Groundwater Environment
• /
• v.6 no.3
• /
• pp.152-157
• /
• 1999

Oil leaked from underwound storage tanks and leachate from sanitary landfills have been known as contaminant sources of the high-quality groundwater resources. The mobility of contaminants in the aquifer largely depends on the groundwater flow and the determination of associated hydraulic parameters is essential for a proper remediation of contaminated grnundwater. This study aimed at determining an optimum set of hydraulic parameters for an unconfined sandy aquifer of a laboratory scale through comparison of various methods. Results showed that the specific yield obtained from gravity drainage experiment was an average of 0.20 with minor variations in aquifer depths. and the permeabilities obtained from Dupuit approximation and slug test gave similar values of 5.33 cm/min and 5.85 cm/min but the constant head method gave 0.17 cm/min, which is much ion than the other methods. This experimental evidence reveals that the permeability of the unconfined sandy aquifer could be accurately determined by Dupuit assumption or slug tut rather than by constant head method conducted for a disturbed separate soil column.

• Journal of Chest Surgery
• /
• v.39 no.3 s.260
• /
• pp.214-219
• /
• 2006

Background: Perforation of esophagus is relatively uncommon. but it is associated with high morbidity and mortality. Treatment and outcome are largely determined by the time of presentation. We performed a retrospective review of patients with esophageal perforation to assess the outcome of current management techniques. Material and Method: A retrospective chart review was performed on all patients treated for perforation of esophagus from March 1990 to March 2005. There were 28 patients (22 men and 6 women: mean age 51 years, range 17 to 82 years) The causes of the perforations were as follows: foreign body retention (9 patients), trauma (7 patients), spontaneous rupture (7 patients), and iatrogenic (5 pati-ients). 18 patients were presented within 24 hours and 10 patients were presented after 24 hours., Esophageal repair was performed in 21 ($75\%$) of them, 4 patients were treated with esophagectomy, 3 patients were treated with feeding gastrostomy and drainage. Result: Hospital mortality was $18\%$ and iatrogenic was increase the mortality rate (p < 0.05). Site of perforation, time from perforation, and treatment method had no influence on mortality. Postoprative leaks occurred in 4 patients after primary repair and were treated conservatively. Conclusion: Esophageal perforation remains a devastating event which is difficult to diagnose and manage. Primary repair can be performed in most patients with esophageal perforation regardless of time to presentation with a low mortality. Accurate diagnosis and early treatment are essential to the successful management of patients.

• Land and Housing Review
• /
• v.8 no.3
• /
• pp.189-200
• /
• 2017

The work breakdown structure and the precedence relations by work activity are very important because they are the basic data for estimating the construction duration in the construction work. However, there is no standard to accurately estimate the construction duration since the size of the school facilities construction is smaller than the general construction work. Therefore, some schools are unable to open in March or September and the delay of the construction duration can cause damage to the students. To solve this problem, this study developed a work breakdown structure of school facilities construction work and analyzed the precedence relations by work activities. The work breakdown structure of the school facilities construction is composed of three steps. The operations corresponding to level 1 and level 2 are as follows. (1) 2 preparatory work categories; preparation period and temporary construction. (2) 17 architectural work categories; temporary construction, foundation & pile work, reinforced concrete work, steel roof work, brick work, plaster work, tile work, stone work, waterproof construction, wood work, interior construction, floor work, metal work, roof work, windows construction, glazing work and paint construction. (3) 7 mechanic and fire work categories; outside trunk line work, plumbing work, air-conditioning equipment work, machine room work, city gas plumbing work, sanitation facilities and inspection & test working. (4) 4 civil work categories; wastewater work, drainage work, pavement work and other work. (5) 1 landscaping work categories; planting work. The work breakdown structure was derived from interviews with experts based on the milestones and detailed statements of existing school facilities. The analysis of precedence relations by school facilities work activity utilized PDM(Precedence Diagramming Method)which does not need a dummy and the relations were applied using FS(Finish to Start), FF(Finish to Finish), SS(Start to Start), SF(Start to Finish). The analysis of this study shows that if one work activity is delayed, the entire construction duration may be delayed because the majority of the works are FS relations. Therefore, it is necessary to use the Lag at the appropriate time to estimate the standard construction duration of the school facility construction. Lag is a term used only in the PDM method and it is used to define the relationship between the predecessor and the successor in creating the network milestone. And it means the delay time applied to the two work activities. The results of this study can reasonably estimate the standard construction duration of school facilities and it will contribute to the quality of the school facilities construction.

• Journal of Korea Water Resources Association
• /
• v.40 no.1 s.174
• /
• pp.73-88
• /
• 2007

The goal of this research is to develop and apply the generalized regression neural networks model(GRNNM) embedding genetic algorithm(GA) for the estimation and calculation of the pan evaporation(PE), which is missed or ungaged and of the alfalfa reference evapotranspiration ($ET_r$), which is not measured in South Korea. Since the observed data of the alfalfa 37. using Iysimeter have not been measured for a long time in South Korea, the Penman-Monteith(PM) method is used to estimate the observed alfalfa $ET_r$. In this research, we develop the COMBINE-GRNNM-GA(Type-1) model for the calculation of the optimal PE and the alfalfa $ET_r$. The suggested COMBINE-GRNNM-GA(Type-1) model is evaluated through training, testing, and reproduction processes. The COMBINE-GRNNM-GA(Type-1) model can evaluate the suggested climatic variables and also construct the reliable data for the PE and the alfalfa $ET_r$. We think that the constructive data could be used as the reference data for irrigation and drainage networks system in South Korea.

• Journal of Soil and Groundwater Environment
• /
• v.14 no.4
• /
• pp.45-53
• /
• 2009

This study concerned remediation of heavy metal contaminated farmland soils near abandoned mine, using stabilization method, with particular emphasis on the remediating the soils contaminated with multi-elements. In this study, stabilizing heavy metals based on 'In-situ chemical fixation' has been applied to the soil collected from an abandoned mine in Korea, using column test, with various stabilizing agents, including $FeSO_4$, $KMnO_4$, sludge (collected from coal mine drainage treatment pond), zero-valent iron (ZVI), zeolite and $CaCO_3$. Sixty five-days operation of the flow-through columns yield $FeSO_4\;+\;KMnO_4$ and zeolite are efficient on reducing As leaching from the soil. ZVI and sludge are reducing the leaching of Cu. Although $FeSO_4\;+\;KMnO_4$ seem to be efficient for most heavy metals, high pH in the initial stage of test enabled high leaching of the heavy metals, whereas fixation of the heavy metals maintain throughout the rest of the test period, with increasing pH up to around 6. Addition of some alkaline agent may inhibit the low pH during the application. The column test was also run as two set: one set incubated with deionized water for 72 hours prior to starting the test, and the other without incubation. The incubated set demonstrated better stabilizing efficiency, indicating the potential optimized operation method.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.22 no.5
• /
• pp.1-12
• /
• 2019

It is important to measure the height of trees as an essential element for assessing the forest health in urban areas. Therefore, an automated method that can measure the height of individual tree as a three-dimensional forest information is needed in an extensive and dense forest. Since airborne LiDAR dataset is easy to analyze the tree height(z-coordinate) of forests, studies on individual tree height measurement could be performed as an assessment forest health. Especially in urban forests, that adversely affected by habitat fragmentation and isolation. So this study was analyzed to measure the height of individual trees for assessing the urban forests health, Furthermore to identify environmental factors that affect forest growth. The survey was conducted in the Mt. Bongseo located in Seobuk-gu. Cheonan-si(Middle Chungcheong Province). We segment the individual trees on coniferous by automatic method using the airborne LiDAR dataset of the two periods (year of 2016 and 2017) and to find out individual tree growth. Segmentation of individual trees was performed by using the watershed algorithm and the local maximum, and the tree growth was determined by the difference of the tree height according to the two periods. After we clarify the relationship between the environmental factors affecting the tree growth. The tree growth of Mt. Bongseo was about 20cm for a year, and it was analyzed to be lower than 23.9cm/year of the growth of the dominant species, Pinus rigida. This may have an adverse effect on the growth of isolated urban forests. It also determined different trees growth according to age, diameter and density class in the stock map, effective soil depth and drainage grade in the soil map. There was a statistically significant positive correlation between the distance to the road and the solar radiation as an environmental factor affecting the tree growth. Since there is less correlation, it is necessary to determine other influencing factors affecting tree growth in urban forests besides anthropogenic influences. This study is the first data for the analysis of segmentation and the growth of the individual tree, and it can be used as a scientific data of the urban forest health assessment and management.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
• /
• v.14 no.3
• /
• pp.184-192
• /
• 2021

Domestic agriculture is facing real problems, such as a decrease in the population in rural areas, a shortage of labor due to an aging population, and increased risks due to the deepening of climate change. Smart farming technology is being developed to solve these problems. In the development of smart agricultural technology, irrigation control plays an important role in creating an optimal growth environment and is an important issue in terms of environmental protection. This paper is about the study of collecting and analyzing the rhizosphere environmental data of domestic paprika farms for the purpose of improving the quality of crops, reducing production costs, and increasing production. Irrigation control modeling presented in this paper Control modeling is to graphically present changes in a medium weight, feed, and drainage due to regional climatic features. To derive the graph, the parameters were determined through data collection and analysis, and the suggested irrigation control modeling method was applied to the collected rhizosphere environmental data to control irrigation in 6 regions (Gangwon-do, Chungnam, Jeonbuk, Jeonnam, Gyeongbuk, and Gyeongnam). The parameters were obtained and graphs were derived from them. After that, a study was conducted to analyze the derived parameters to verify the validity of the irrigation control modeling method and to correlate them with climatic features (average temperature and precipitation).

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.11 no.2
• /
• pp.131-140
• /
• 2009

It has been repeatedly reported that a drainage system of a drained tunnel is deteriorated. And consequently the water pressure on the lining increases with time. However, little research on the watertight tunnel was found in the literatures. According to field measurements, leakage of the undrained tunnel has increased with time, which is completely opposite to the behavior of the drained tunnel. It is evident that the hydraulic deterioration of the tunnel lining changes the water pressure on the lining and the amount of leakage, thus the design coneept in terms of groundwater is not maintained tightly throughout the life time of the tunnel. The Segment lining is generally constructed as watertight. However, it is frequently reported that the leakage in the segment tunnel increases with time. It is also reported that the leakage is generally concentrated at the joints of the segments. In this study structural and hydraulic interaetion of the segment lining due to the hydraulic deterioration of the segments and the joints is investigated using the numerical modeling method. An electric utility tunnel below groundwater table is considered for the analyses. The effects of hydraulic deterioration of the segment lining are identified in terms of ground loading, water pressure and lining behavior. A remedial grouting measure for leakage is also numerically simulated, and its appropriateness is evaluated.

• The Korean Journal of Pesticide Science
• /
• v.19 no.3
• /
• pp.255-263
• /
• 2015

Promoting the organic farming, much of the plant extracts used for controlling pests and fungi have been imported from China, India and Myanmar. But, it is so worrisome that aquatic animals such as muddy loach inhabiting in paddy field and common carps in river exposed to the pests and fungi likely be harmed. This study was conducted in order to evaluate the risks of aquatic animals influenced by the three plant extracts, i.e. Sophora flavescens, Azadirachta indica and Derris elliptica. The toxicities of common carp (Cyprinus Carpio), muddy loach (Misgurnus anguillicaudatus) and PEC (Predicted environmental concentration) exposed to the three plant extracts were estimated by the typical spray volume method. Risks were determined by the toxicity value as 48-hr $LC_{50}$ (Lethal concentration, median) or NOEC (No observed effect concentration) into PEC. 48-hr $LC_{50}$ of Common carp and NOEC by Sophora flavescens extracts was 7.9 and 6.2 mg/L, 26.8 and 21.8 mg/L by Azadirachta indica extracts and 47.0 and < 24.0 mg/L by Derris elliptica extracts, respectively. 48-hr $LC_{50}$ of Muddy loach and NOEC by Sophora flavescens extracts was 16.9 and 10.0 mg/L, 35.6 and 30.0 mg/L by Azadirachta indica extracts, and 73.9 and < 40 mg/L by Derris elliptica extracts, respectively. Therefore, acute toxicities of the three plant extracts for aquatic animals were proved to be very low level. PEC of Sophora flavescens extracts in paddy, drainage and river water was 68.0~3.0, 11.33~0.50 and 3.0~0.0018 mg/L, respectively. TER of Sophora flavescens extracts in the three water was 0.2~5.6, 1.5~33.8 and 2.6~4388.9, respectively. PEC of Azadirachta indica extracts in paddy, drainage and river water was 90.9~1.2, 15.2~0.2 and 4.8~0.00075 mg/L, respectively. TER of Azadirachta indica extracts in the three water was 0.4~29.7, 2.3~178.0 and 4.5~35733.3, respectively. PEC of Derris elliptica extracts in river water was 0.0063 mg/L. TER of Derris elliptica extracts in river water was 5222~15667.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.33 no.6
• /
• pp.2255-2265
• /
• 2013

This study presents the width function-based Clark model. To this end, rescaled width function with distinction between hillslope and channel velocity is used as time-area curve and then it is routed through linear storage within the framework of not finite difference scheme used in original Clark model but analytical expression of linear storage routing. There are three parameters focused in this study: storage coefficient, hillslope velocity and channel velocity. SCE-UA, one of the popular global optimization methods, is applied to estimate them. The shapes of resulting IUHs from this study are evaluated in terms of the three statistical moments of hydrologic response functions: mean, variance and the third moment about the center of IUH. The correlation coefficients to the three statistical moments simulated in this study against these of observed hydrographs were estimated at 0.995 for the mean, 0.993 for the variance and 0.983 for the third moment about the center of IUH. The shape of resulting IUHs from this study give rise to satisfactory simulation results in terms of the mean and variance. But the third moment about the center of IUH tend to be overestimated. Clark model proposed in this study is superior to the one only taking into account mean and variance of IUH with respect to skewness, peak discharge and peak time of runoff hydrograph. From this result it is confirmed that the method suggested in this study is useful tool to reflect the heterogeneity of drainage path and hydrodynamic parameters. The variation of statistical moments of IUH are mainly influenced by storage coefficient and in turn the effect of channel velocity is greater than the one of hillslope velocity. Therefore storage coefficient and channel velocity are the crucial factors in shaping the form of IUH and should be considered carefully to apply Clark model proposed in this study.