• Journal of Dental Rehabilitation and Applied Science
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• v.18 no.4
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• pp.301-311
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• 2002

The purpose of this study was to compare the distributing pattern of stress on the finite element models with the different vertical bone level of implant fixture. The two kinds of finite element models were designed according to vertical bone level around fixture ($4.0mm{\times}11.5mm$). The cemented crowns for mandibular first and second molars were made. Three- dimensional finite element model was created with the components of the implant and surrounding bone. Vertical loads were applied with force of 200N distributed within 0.5mm radius circle from the center of central fossa and distance 2mm and 4 mm apart from the center of central fossa. Von-Mises stresses were recorded and compared in the supporting bone, fixtures, abutment screws, and crown. The results were as following : (1) In vertical loading at the center circle of central fossa on model 1 and 2, the difference from vertical bone in implant placement did not affect the stress pattern on all components of implant except for crown. (2) With offset distance incerasing and the bone level of implant decreasing, the concentration of stress occured in the buccal side of long crown, around the buccal crestal bone, and on the fixture- abutment interface. As a conclusion, the research showed a tendency to increase the stress on the supporting bone, fixture and screw under the offset loads when the vertical level of bone around fixture was different. Since the same vertical bone bed has more benefits than the different bone bed around fixtures, it is important to prepare a same vertical level of bone bed for the success of implants under occlusal loads.

• Journal of Korean Society on Water Environment
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• v.34 no.4
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• pp.382-390
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• 2018

In this study, the LIDMOD3 was developed to design and evaluate low impact development (LIDMOD). In the same fashion, the LIDMOD3 employs a curve number (NRCS-CN) method to estimate the surface runoff, infiltration and event mean concentration as applicable to pollutant loads which are based on a daily time step. In these terms, the LIDMOD3 can consider a hydrologic soil group for each land use type LID-BMP, and the applied removal efficiency of the surface runoff and pollutant loads by virtue of the stored capacity, which was calculated by analyzing the recorded water balance. As a result of Model development, the LIDMOD3 is based on an Excel spread sheet and consists of 8 sheets of information data, including: General information, Annual precipitation, Land use, Drainage area, LID-BMPs, Cals-cap, Parameters, and the Results. In addition, the LIDMOD3 can estimate the annual hydrology and annual pollutant loads including surface runoff and infiltration, the LID efficiency of the estimated surface runoff for a design rainfall event, and an analysis of the peak flow and time to peak using a unit hydrolograph for pre-development, post-development without LID, and as calculated with LID. As a result of the model application as applied to an apartment, the LIDMOD3 can estimate LID-BMPs considering a well spatical distributed hydroloic soil group as realized on land use and with the LID-BMPs. Essentially, the LIDMOD3 is a screen level and simple model which is easy to use because it is an Excel based model, as are most parameters in the database. This system can be expected to be widely used at the LID site to collect data within various programmable model parameters for the processing of a detail LID model simulation.

• Journal of Korea Water Resources Association
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• v.36 no.5
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• pp.787-797
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• 2003

The characteristics of concentrations and loads of Total Nitrogen(T-N), Total Phosphorus(T-P), and Chemical Oxygen Demand (COD) in mountain stream water were examined from September 2000 through August 2001. The 92.5-ha study watershed in Chungbuk Province consists of 59% mixed forest and 30% coniferous forest. Streamflow was measured and water samples were collected at about 10 day intervals for dry days and at 2-6 hour intervals for a storm event at the study watershed outlet. The mean concentration of COD in streamflow for rainy days was significantly (p < 0.05) higher than for dry days. The mean concentrations of T-N and T-P in vegetation growing season (May to October) were lower than those in vegetation dormant season (November to April). Low concentrations of pollutants during vegetation growing season are likely due to the heavy demand for nutrients by the vegetation and biological activity associated with a warming of soil. The ratios of pollutants loads during storm periods to annual pollutants loads were 87% for T-N, 83% for T-p, and 87% for COD. The unit loads of pollutants for study area were estimated at 5.9 kg/ha $\cdot$ yr for T-N, 0.15 kg/ha $\cdot$ yr for T-p, and 23.9 kg/ha $\cdot$ yr for COD. The removal efficiency of pollutants in study area were 24% for T-N, 58% for T-P and 66% for COD, indicating that a study area shows water purification function.

• Korean Chemical Engineering Research
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• v.51 no.2
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• pp.272-278
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• 2013

The hybrid system composed of a photocatalytic reactor and a biofilter was operated under various operating conditions in order to treat malodorous waste air containing ammonia which is a major air pollutant emitted from composting factories and many publicly owned treatment works. Total ammonia removal efficiency of the hybrid system was maintained to be ca. 80% even though its inlet loads were increased at a higher operating stage according to an operating schedule of the hybrid system. The ammonia removal efficiency of photocatalytic reactor was decreased from 65% to 22% as ammonia inlet loads to photocatalytic reactor were increased. In spite of same inlet loads of ammonia to the photocatalytic reactor, the ammonia removal efficiency of photocatalytic reactor with lower ammonia concentration of fed-waste air was higher than that with higher ammonia concentration of fed-waste air. To the contrary, during the first half of the hybrid system operation the ammonia removal efficiency of a biofilter was quite suppressed while, despite of increased ammonia inlet loads, the ammonia removal efficiency of the biofilter was continuously increased to 78% and reached the ammonia removal efficiency similar to what Lee et al. attained. The maximum ammonia elimination capacity of the photocatalytic reactor was observed to be ca. 16 g-N/$m^3$/h. In an incipient stage of hybrid system run, the ammonia elimination capacity of the biofilter showed little sensitivity against ammonia inlet loads to the hybrid system. However, in the 2nd half of its run, the ammonia elimination capacity of the biofilter was increased abruptly in case of high ammonia inlet loads to the hybrid system. In 6th stage of hybrid system run, total ammonia inlet load attained at ca. 80 g-N/$m^3$/h corresponding to 16 g-N/$m^3$/h of ammonia elimination capacity of the photocatalytic reactor. Then, the remaining ammonia inlet load to the 2nd and main process of the biofilter and its elimination capacity was expected and shown to be ca 64 g-N/$m^3$/h and ca 48 g-N/$m^3$/h, respectively. The ammonia elimination capacity of the biofilter was close to 1,200 g-N/$m^3$/day of the maximum elimination capacity of the investigation performed by Kim et al.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.16 no.4
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• pp.196-205
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• 2004

Water qualities (WQ) were measured biweekly from April 2nd to October 29th, 2003 in Sillicheon flowing into the entrance of Jumunjin Harbour and daily water quantities (river discharges) were estimated by the TANK model which has been widely used to compute the runoff discharges in the ungauged watersheds. The spatial and temporal change patterns of the measured WQs were analysed in detail and the correlation between rainfall - WQ and river discharge - WQ were also analysed. From this results, it is found that the correlation coefficient between BOD concentration and rainfall is 0.75 and between the SS concentration and 2-days river discharge is 0.36. The correlation between the COD, TN, TP in the station of Silli Lower Bridge and rainfall runoff quantity was analysed as un-correlated items. As a consequence, the estimated BOD and SS pollutants loads are reliable and show good change patterns even though the accuracy of SS pollutants load is slightly low. The estimated COD, TN and TP pollutants loads, however, can be used only as the reference or averaged values. In order to analyse more accurately the temporal change patterns of these items, more-detailed researches considering the artificial effects and landuse patterns are highly required.

• Journal of the Korean Society for Marine Environment & Energy
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• v.2 no.1
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• pp.63-73
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• 1999

The results of residual currents simulation by a three-dimensional hydrodynamic model showed the water volume transport and the residence time to be about 4km³ per tidal cycle and about 6 years through the line of latitude, 34° 25' N in the Yellow Sea, and to be about 13km³ per tidal cycle and about 2.5 years through the southeastern boundary line of the Yellow Sea, respectively. On the bases of the entire seawater volume of the Yellow Sea and dissolved oxygen (DO) in summer, the environmental capacity of the Yellow Sea for reception of the maximum pollution load without reducing DO concentration below 5.0mg/ℓ in seawater may be estimated to be about 58×10/sup 6/tons of chemical oxygen demand (COD), which is equivalent to the load about 8 times as high as the annual organic pollution load from 14 major rivers. On the bases of DO transports by residual currents calculated on the line of 34° 25' N latitude and on the southeastern boundary line of the Yellow Sea being about 57×10³tons and about 203×10³tons of DO per day, respectively, the environmental capacities of the Yellow Sea for reception of the maximum pollution loads without reducing DO concentration in seawater nay be equivalent to COD loads about 3 times and 10 times, respectively, as high as the existing organic pollution loads from 14 major rivers.

• Journal of Korea Spatial Information System Society
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• v.9 no.3
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• pp.35-50
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• 2007

In a data centric sensor network, a sensor node to store data is determined by the measured data value of each sensor node. Therefore, if the same data occur frequently, the energy of the sensor node to store the data is exhausted quickly due to the concentration of loads. And if the sensor network is extended, the communication cost for storing data and processing queries is increased, since the length of the routing path for them is usually in the distance. However, the existing researches that generally focus on the efficient management of data storing can not solve these problems efficiently. In this paper, we propose a NUNS(Non-Uniform Network Split) method that can distribute loads of sensor nodes and decrease the communication cost caused by the sensor network extension. By dividing the sensor network into non-uniform partitions that have the minimum difference in the number of sensor nodes and the splitted area size and storing the data which is occurred in a partition at the sensor nodes within the partition, the NUNS can distribute loads of sensor nodes and decrease the communication cost efficiently. In addition, by dividing each partition into non-uniform zones that have the minimum difference in the splitted area size as many as the number of the sensor nodes in the partition and allocating each of them as the processing area of each sensor node, the NUNS can protect a specific sensor node from the load concentration and decrease the unnecessary routing cost.

• Journal of Environmental Science International
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• v.25 no.2
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• pp.217-229
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• 2016

The government has conducted a plan of total maximum daily loads(TMDL), which divides with unit watershed, for management of stable water quality target by setting the permitted total amount of the pollutant. In this study, BOD concentration trends over the last 10 years from 2005 to 2014 were analyzed in the Geumho river. Improvement effect of water quality throughout the implementation period of TMDL was evaluated using the seasonal Mann-Kendall test and a LOWESS(locally weighted scatter plot smoother) smooth. As a study result of the seasonal Mann-Kendall test and the LOWESS smooth, BOD concentration in the Geumho river appeared to have been reduced or held at a constant. As a result of quantitatively analysis for BOD concentration with exploratory data analysis(EDA), the mean and the median of BOD concentration appeared in the order of GH8 > GH7 > GH6 > GH5 > GH4 > GH3 > GH2 > GH1. The monthly average concentration of BOD appeared in the order of Apr > Mar > Feb >May > Jun > Jul > Jan > Aug > Sep > Dec > Nov > Oct. As a result of the outlier, its value was the most frequent in February, which is estimated 1.5 times more than July, and was smallest frequent in July. The outlier in terms of water quality management is necessary in order to establish a management plan for the contaminants in watershed.

• Journal of Environmental Science International
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• v.22 no.3
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• pp.259-267
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• 2013

In this study, non-point source(NPS) contribution was investigated based on flow rates and water qualities of streams into the lake during rainfall events. Event mean concentration(EMC) and the pollution loads were calculated to establish a database for NPS control measurement in the survey area, and so on. The runoff characteristics of NPS were investigated and estimated on the basis of the ratio of an agricultural to forest area in the stream of sub-catch basin during rainfall events. Non-point source pollution loads were also calculated to establish a database for NPS control measure in the upstream lake Chinyang. At a rainfall event, BOD concentrations rise sharply at the early peak time of runoff, however, peaks of TSS concentration were observed at the similar time of peak flow. This was a phenomenon shown at the watersheds caused by forest and geological types. The discharged EMC range was 2.9-4.8 mg/L in terms of BOD. The discharged EMC range was 6.2-8.2 mg/L in terms of SS. The discharged EMCs of T-N and T-P were 1.4-2.5 mg/L and 0.059-0.233 mg/L, respectively. Total BOD loading rate through the 3 tributaries to the lake Chinyang was 1,136 kg/d during dry weather. The upper watershed area of the Nam-river dam in this study was divided into 14 catchment basins based on the Korean guideline for total maximum daily load(TMDL) of water quality pollutants. The higher the agricultural land-use ratio, the more NPS loading rate discharged, but the more occupied a forest area, the lower more NPS loading rate discharged. In an agricultural land-use area more than 20%, the increase of NPS loadings might be dramatically diffused by increasing the integrated complex-use like vinyl-house facilities and fertilizer use etc. according to the effective land-use utilization. The NPS loading rates were BOD 0.3 $kg/ha{\cdot}day$, SS 0.21 $kg/ha{\cdot}day$, TN 0.02 $kg/ha{\cdot}day$, TP 0.005 $kg/ha{\cdot}day$ under less than 10% agricultural land-use. In agricultural land-use of 20%-50%, these values were investigated in the range of 0.32 $kg/ha{\cdot}day$-0.73 $kg/ha{\cdot}day$ for BOD, 0.92 $kg/ha{\cdot}day$-3.32 $kg/ha{\cdot}day$ for SS, 0.70 $kg/ha{\cdot}day$-0.90 $kg/ha{\cdot}day$ TN, 0.03 $kg/ha{\cdot}day$-0.044 $kg/ha{\cdot}day$ for TP.

• Journal of Environmental Science International
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• v.22 no.12
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• pp.1643-1650
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• 2013

This study investigated water quality of effluents and stream from the sewage treatment plants located at Gumi Complex 4, Gumi, and Wonpyeong in Gumi. Downstream region was found to increase the concentration of nutrients for sewage treatment plant effluent. Both phosphorus and nitrogen were accounted most as soluble form. In particular, the high ratio of dissolved effluent of sewage treatment plants were investigated. In the streams, Phosphorus concentration was high during rainy season and nitrogen concentration was high in the dry season. Sewage treatment plant effluent was relatively less microbial activity and nutrient concentrations were higher in the winter. TN/TP ratio was the highest in the upstream region and the lowest in the sewage treatment plant effluent. The effect of the nutrient matter from a discharge of a sewage treatment plant on rivers varied depending on the size of the river and the treatment plant. However, the influence of the concentration was greater than that of flowrate. Sewage treatment plant effluent loads phosphorus, nitrogen accounted for 8% and 6% respectively at the point N3 of the Nakdong river.