• Journal of the Korean Geotechnical Society
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• v.37 no.7
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• pp.13-23
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• 2021

If roads, bridges, buildings, etc. are built on the ground with soft clay or organic soil, there may be a lot of problems in geotechnical engineering such as settlement and stability due to the large settlement and lack of bearing capacity. In extreme cases, it may appear due to shear failure or collapse of the constructed structure, so a ground improvement method is indispensable to increase the strength of the ground and to suppress settlement. In this study, the settlement according to each groundwater level condition was analyzed using the measurement results for the groundwater level conditions, one of the important factors in predicting the settlement in dredged and reclaimed ground, and the groundwater level conditions applied to the settlement analysis were proposed by comparing it with settlement generated 5 years after construction. As a result of the analysis, it is judged that it is reasonable to apply the measured groundwater level during construction and the low water ordinary neap tide (L.W.O.N.T) during load application for the groundwater level in the settlement analysis. In addition, in the case of the dredged and reclaimed ground, it is estimated that the water pressure acting on the clay layer is nonlinear, as the result of the observations of the head of water at the observation points above and below the in-situ clay layer were different.

• Korean Journal of Environmental Agriculture
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• v.32 no.1
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• pp.78-83
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• 2013

BACKGROUND: This study was performed to investigate the change of deltamethrin residue after spraying for control of hygienic insects in bush of levee at Bansuk-dong stream (A) and Juk-dong ditch (B) in Yuseong, Daejeon. The drop concentrations and disappearance of deltamethrin residue in stream water were determined to evaluate the toxic effects of stream ecosystem. METHODS AND RESULTS: Water samples were collected at 7 points including 0, 5, 10, 20, 40, 70 and 100 m downstream from the deltamethrin spraying point. Water sample was partitioned into dichloromethane, and was determined with GC/${\mu}$-ECD. Limit of Quantitation of deltamethrin was 0.04 ${\mu}g/L$. Recoveries of deltamethrin at two fortification levels of 0.4 and 2.0 ${\mu}g/L$ were $91.57{\pm}3.13%$(n=3) and $94.40{\pm}4.59%$(n=3) in A stream, and $88.24{\pm}3.33%$(n=3) and $85.20{\pm}3.73%$(n=3) in B stream, respectively. Residue of A stream were from <0.04 ${\mu}g/L$ to 0.48 ${\mu}g/L$ and B stream were from 0.08 ${\mu}g/L$ to 14.95 ${\mu}g/L$ under practice application condition. And residues were from <0.04 ${\mu}g/L$ to 0.2 ${\mu}g/L$ in A stream treated deltamethrin with 1.0 mg level at the upper region. CONCLUSION(S): Practice application of deltamethrin for the pest control of waterside was not much shown toxic effect to ecosystem of stream.

• Current Research on Agriculture and Life Sciences
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• v.29
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• pp.11-19
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• 2011

This research gives weight to establish practical improvement based on analysis of the landscape ecological character and value to realize the importance of small wetland and stream in cultivated areas functioning as a residual landscape element in rural landscape and to deal with ecological depression effectively. The results of summary are as follows. 1) The results of landscape ecological character analysis of wetlands biotop in total of 7 sites, for example, size of surface in site 5 was widely formed about $10,600m^2$, which was assessed satisfactory in terms of slope of waterfront, width of hedgerow, vegetation condition of composition and so on. Also, The number of flexibility showed 2 in site 8-1, the highest, and morphological diversity showed 1.47, the highest. 2) The results of problem analysis of wetland biotop, most of wetlands are analyzed that the width of hedgerow was below 1m. Also, the 4 wetlands in site 8 are appeared that hard to live slope vegetation in there because of slope of waterfronts are above $45^{\circ}$. 3) The results of landscape ecological character analysis of stream in total of 6 sites, for example, width of waterfront in site 4 showed 55m, the widest, and investigated consist of natural ingredients such as soil, rock, gravel. However, width of waterfront in site 2-2 showed 4m, the narrowest, and inclined angle of slope was formed a right angle. 4) The results of problem analysis of stream, width of waterfront hedgerow in site 2-1 showed about 5m, which was very narrower than width of waterfront, and toxic chemicals discharged from near cultivated area without any filtering. Also, all areas of site 2-2 was formed concrete, and was assessed dissatisfactory in terms of capacity of nature purification, flood control, habitat living space because of straight stream. 5) Based on the result above landscape ecological character and problem analysis, main improvement guidelines are set in terms of shape, vegetation, topography in case of wetlands, and which are set in terms of vertical, horizontal structure in case of stream.

• Journal of Animal Science and Technology
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• v.50 no.4
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• pp.561-572
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• 2008

Responses of real-time control parameters, such as ORP, DO and pH, to the conditions of biological animal wastewater treatment process were examined to evaluate the stability of real-time control using each parameter. Also an optimum index for supplemental carbon source addition based on NOx-N level was determined under a consideration of denitrification rate by endogenous respiration of microorganism and residual organic matter in liquor. Experiment was performed with lab-scale sequencing batch reactor(SBR) and working volume of the process was 45L. The distinctive nitrogen break point(NBP) on ORP-and DO-time profiles, which mean the termination of nitrification, started disappearing with the maintenance of low NH4-N loading rate. Also the NBP on ORP-and DO-time profiles was no longer observed when high NOx-N was loaded into the reactor, and the sensitivity of ORP became dull with the increase of NOx-N level. However, the distinctive NBP was constantly occurred on pH(mV)-time profile, maintaining unique profile patterns. This stable occurrence of NBP on pH(mV)-time profile was lasted even at very high NOx-N:NH4-N ratio(over 80:1) in reactor, and the specific point could be easily detected by tracking moving slope change(MSC) of the curve. Revelation of NBP on pH(mV)-time profile and recognition of the realtime control point using MSC were stable at a condition of over 300mg/L NOx-N level in reactor. The occurrence of distinctive NBP was persistent on pH(mV)-time profile even at a level of 10,000mg/L STOC(soluble total organic carbon) and the recognition of NBP was feasible by tracing MSC, but that point on ORP and DO-time profiles began to disappear with the increase of STOC level in reactor. The denitrfication rate by endogenous respiration and residual organic matter was about 0.4mg/L.hr., and it was found that 0.83 would be accepted as an index for supplemental carbon source addition when 0.1 of safety factor was applied.

• Korean Chemical Engineering Research
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• v.50 no.1
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• pp.18-24
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• 2012

Lignocellulose is difficult to hydrolyze due to the presence of lignin and the technology developed for cellulose fermentation to ethanol is not yet economically viable. However, recent advances in the extremely new field of biotechnology for the ethanol production are making it possible to use of Agriculture residual biomass, e.q., Barley straw, because of their several superior aspects as Agriculture residual biomass; low lignin, high contents of carbohydrates. Barley straw consists of 39.78% cellulose (glucose), 22.56% hemicelluloses and 19.27% lignin. Pretreatment of barley straw using NaOH pretreatment solutions concentration with 2%, temperature $85^{\circ}C$ and reaction times 1 hr were investigates. $NH_4OH$ pretreatment condition was solutions concentration with 15%, temperature $60^{\circ}C$, and reaction times 24hr were investigates. Furthermore, enzymatic saccharification using cellulose at $50^{\circ}C$, pH 4.8, 180 rpm for conversion of cellulose contained in barley straw to monomeric sugar. The pretreatment of barley straw using NaOH and $NH_4OH$ can significantly improve enzymatic saccharification of barley straw by extract more lignin and increasing its accessibility to hydrolytic enzymes. The result showed NaOH pretreatment extracted yield of lignin was 24.15%. $NH_4OH$ pretreatment extracted yield of lignin was 29.09%. Shaccharification of barley straw pretreatment by NaOH for 72hr and pH 4.8 result in maximum glucose concentration 15.39g/L (58.40%) and by $NH_4OH$ for 72hr and pH 4.8 result in maximum glucose concentration 16.01g/L (64.78%).

• Journal of Chest Surgery
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• v.29 no.9
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• pp.945-950
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• 1996

Twelve patients with left ventricular-right atrial shunt (LV-RA shunt) underwent surgical correction be- tween April 1982 and March 1995. Seven patients were male and five patients were female. Age ranged from 3 to 26 years with mean age of 8.5 years. On the preoperative chest PA views, increased pulmonary vascularity was noted in 3 cases and enlargement of right atrium in 4 cases. The mean preoperative cardiothoracic ratio was 0.59. Echocardiographic studies were obtained in 9 patients and the preoperative echocardiographic diagnoses were LV-RA shunt in 2 cases, ventricular septal defect (VSD) in 6 casei, and atrial septal defect (ASD) in 1 case. The preoperative ngiographic diagnoses which were obtained in all patients were LV-RA shunt in 5 cases, VSD in 5 cases, ASD in 1 case, and VSD with ASD in 1 case. The descriptions of defect of LV-RA shunt according to intraoperative findings were supravalvular defect in 5 cases(42%), infravalvular defect in 4 cases (33%), and combined defect in 3 cases (25%). Associated anomalies of tricuspid valve in 4 cases of infravalvular defect were perforation (3 cases) and cleft (1 case). Primary closure of the septal defect was performed through the right atriotomy in all but one patient. There was no operative death. One patient underwent reoperation because of the residual interventricular shunt. All patients have been in good condition.

• Korean Journal of Environmental Agriculture
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• v.29 no.1
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• pp.47-53
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• 2010

The purpose of this study was to investigate the effectiveness of a stabilization treatment for As contaminated soil. A combination of hydrated lime, Portland cement, $FeCl_3{\cdot}6H_2O$, and NaOH were used as stabilizing agents. The effectiveness of stabilization treatment was evaluated by the Korean Standard Test (KST) method (1N HCl extraction). Sequential extractions were performed to investigate the As distribution after treatment. Following the application of the treatment, curing periods of up to 7 and 28days were investigated. The experimental results showed that a combination of hydrated lime/Portland cement was more effective than treatments of hydrated lime or Portland cement at immobilizing As in the contaminated soil. The treatment of 25wt% hydrated lime and 5wt% Portland cement was effective in reducing As leachability less than the Korean warning standard of 20 mg/kg. However, the treatments of hydrated lime and Portland cement failed to meet the Korean warning standard even when up to 30 wt% was used. The treatment utilizing hydrated lime and $FeCl_3{\cdot}6H_2O$ was not effective in properly reducing As leachability. The addition of $FeCl_3{\cdot}6H_2O$ was negative in terms of pH condition. Moreover, the treatment with hydrated lime/NaOH was effective in reducing As leachability but not as much as hydrated lime/Portland cement. The sequential extraction results indicated that the residual phase was greatly increased upon the treatment of hydrated lime/Portland cement. It was concluded that the hydrated lime/Portland cement treatment was the best among the other combinations studied at achieving trace As concentrations.

• Journal of Environmental Health Sciences
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• v.25 no.3
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• pp.13-22
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• 1999

For the purpose of inquiring into the actual conditions of water quality management of Simple Piped Water Supply(SPWS) and the satisfaction and attitudes of inhabitants about utilizing water-supply, this research was done through the questionnaires, the investigation of surrounding environment and water quality analysis in the Sangju city, Kyungsang-pookdo during 4 months from March to June, 1998. The fountainhead of SPES using ground water accounted for 65.3%, which was the highest rate in the group. Most of them was at least 10 years in the number of utilization year. 79.6% of them were exposed to many sorts of surrounding pollution origins. The examination of water was performed only through a test about water purification and 24.5% of them disinfection by chlorine also no residual chlorine was detected at all. All the waterworks did not have any education to the managers of water quality and 81.5% of them held physical examination. As a result of the water examination about SPWS, 65.3% of them were found incongruity and the valley and springing water accounted for higher than the underground water in the rate of incongruity. Looking into the details of the result in the water examination, a category of colon bacilli was ranked in the highest rate and the next one was general bacilli, nitric acid nitrogen and turbidity in order. In the satisfaction degree of the water quality, the satisfied accounted for 44.6%, and 29.2% each. Over the state of satisfaction about the ways of water examination, satisfaction accounted for 44.6%, and unsatisfaction 28.3%. Summarizing the result of the above-stated, the state of Water Quality Management of the SPWS was in a poor condition. Thus for the water Quality Management, systematic and scientific water Quality Management mainly by the administrative organization other than voluntary management by the village should be done beyond doubt. Additionally the opinions and demands of inhabitants utilizing the water supply have to be positively reflected in the affairs of water Quality Management so that the distrust of inhabitants to the SPWS should be settled.

• Journal of Korean society of Dental Hygiene
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• v.10 no.1
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• pp.81-92
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• 2010

Objectives : Thus this study attempted to look into the level of community residents' dental health and the state of their dental diseases and estimate the general dental health condition so that these data can be available as references in upcoming public dental health planning, and to provide fundamental data for promotion of the level of residents' dental health by performing dental health education. Methods : Among community residents who visited the department of Dental Hygiene of Shinsung University for scaling from March to May 2009, the data of total 346 subjects of 129 women and 217 men were selected, and DMFT rate, DMFT index, dental health capacity of the first permanent molar, and tooth morality rate were investigated. For statistical analysis, SPSS 14.0 was used, for general characteristics of the subjects, frequency analysis was conducted, for caries experience in the permanent teeth of the subjects, mean and standard deviation were calculated, for caries experience in the permanent teeth by sex and residence, independent t-test was performed, and for caries experience in the permanent teeth by age, one-way ANOVA was conducted. The significance level applied to these analyses was 0.05. Results : As a result of investigation and analysis on caries in the permanent teeth of community residents who visited the department for scaling in this study, the findings are as follows: 1. For sex, DMFT rate and tooth morality rate were found to be higher in women, while dental health capacity of the first permanent molar was found to be higher in men. 2. For age, DMFT rate and DMFT index were found to be highest in 40~49 years old, while DMFT rate, DMFT index, and tooth morality rate were found to be lowest in under 20 years old. Dental health capacity of the first permanent molar was found to be highest in under 20 years old, 20-29 years old, and 30-39 years old and found to be lowest in more than their sixties as 39.78 points(p<.000). Tooth morality rate was found to be highest in more than their sixties compared to other age groups.(p<.000). 3. For residence, DMFT rate and dental health capacity of the first permanent molar were found to be high in the Metropolitan area, while tooth morality rate was found to be high in Chungcheong area. Conclusions : Seen from the above-mentioned results, great importance shall be attached to the maintenance of residual teeth, and with this, efficient efforts are required to be made for upkeep and promotion of dental health.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.6
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• pp.2369-2379
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• 2013

The Soil-Water Characteristics Curve (SWCC) is affected by the initial density of soil under unsaturated condition. Also, the characteristic of hydraulic conductivity is changed by the initial density of soil. To study the effect of initial density of unsaturated soil, SWCC and the Hydraulic Conductivity Function (HCF) of Jumoonjin sand with various relative densities, 40%, 60% and 75% were measured in both drying and wetting processes. As the results of SWCC estimated by van Genuchten (1980) model, the parameter related to Air Entry Value(AEV), ${\alpha}$ in the wetting process is larger than that in drying process, but the parameters related to the SWCC slope, n and the residual water content, m are larger than those in wetting process. The AEV is increased or Water Entry Value (WEV) is decreased with increasing the relative density of sand. The AEV is larger than the WEV at the same relative density of sand. As the results of HCF estimated by van Genuchten (1980) model which is one of the parameter estimation methods, the unsaturated hydraulic conductivity maintained at a saturated one in the low level of matric suctions and then suddenly decreased just before the AEV or the WEV. The saturated hydraulic conductivity in drying process is larger than that in wetting process. The saturated hydraulic conductivity is decreased with increasing the relative density of sand in both drying and wetting processes. Also, the hysteresis in unsaturated HCFs between drying and wetting process was occurred like the hysteresis in SWCCs. According to the test results, the AEV on SWCC is decreased and the saturated hydraulic conductivity is increased with increasing the initial density. It means that SWCC and HCF are affected by the initial density in the unsaturated soil.