• The Journal of Advanced Prosthodontics
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• v.6 no.1
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• pp.8-13
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• 2014

PURPOSE. The purpose of this study was to evaluate whether surface treatments affect the translucency of laminate veneers with different shades and thicknesses. MATERIALS AND METHODS. A total of 224 disc-shaped ceramic veneers were prepared from A1, A3, HT (High Translucent) and HO (High Opaque) shades of IPS e.max Press (Ivoclar Vivadent) with 0.5 mm and 1.0 mm thicknesses. The ceramics were divided into four groups for surface treatments. Group C: no surface treatments; Group HF: etched with hydrofluoric acid; Group SB: sandblasted with 50-${\mu}m$ $Al_2O_3$; and Group L; irradiated with an Er;YAG laser. A translucent shade of resin cement (Rely X Veneer, 3M ESPE) was chosen for cementation. The color values of the veneers were measured with a colorimeter and translucency parameter (TP) values were calculated. A three-way ANOVA with interactions for TP values was performed and Bonferroni tests were used when appropriate (${\alpha}=0.05$). RESULTS. There were significant interactions between the surface treatments, ceramic shades and thicknesses (P=.001). For the 0.5-mm-thick specimens there were significant differences after the SB and L treatments. There was no significant difference between the HF and C treatments for any shades or thicknesses (P>.05). For the 1-mm-thick ceramics, there was only a significant difference between the L and C treatments for the HT shade ceramics (P=.01). There were also significant differences between the SB and C treatments except not for the HO shades (P=.768). CONCLUSION. The SB and L treatments caused laminate veneers to become more opaque; however, HF treatment did not affect the TP values. When the laminate veneers were thinner, both the shade of the ceramic and the SB and laser treatments had a greater effect on the TP values.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.363-363
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• 2022

LID 시설에 대한 모니터링은 인력을 활용한 실강우 모니터링을 진행하고 있으나 LID 시설은 소규모 분산형시설로서 인력을 동원한 식생고사, 강우시 모니터링, 현장답사 등 꾸준한 시설확인에 한계가 있으며, LID 시설을 조성한 이후 적정한 유지관리 방법(주기, 빈도, 항목 등)을 인지하지 못하여 막힘현상, 효율저하, 식물고사 등의 문제가 발생한다. 따라서 본연구에서는 딥러닝 분석을 활용하여 강우시 강우모니터링 자료와 LID 시설 내 센서를 통해 측정된 자료를 통해 침투도랑 내 유입수 성상에 대한 예측분석을 수행하였다. 심지 내 LID 시설에 유입되는 오염물질을 예측을 위한 딥러닝 분석을 위해 과거 실강우시 모니터링 자료(TSS, COD, TN, TP)와 대기센서(대기습도, 대기온도, 강수량, 미세먼지) 데이터를 활용하여 딥러닝 모델에 대한 적용가능성 평가를 수행하였다. 측정항목에 대한 상관성 분석을 수행하였으며, 딥러닝 모델은 Tenser Flow를 이용하여 DNN(Deep Neural Network)모델을 활용하여 분석하였다. DNN 모델에 대한 MSE값은 0.31로 분석되었으며, TSS에 대한 평균 50.6mg/L로 분석되었으며, COD 평균 98.7 mg/L로 나타났다. TN의 평균 2.21 mg/L로 분석되었으며, TP 평균 0.67 mg/L로 나타났다. 상관계수분석결과 TSS는 0.53로 분석되었으며, TN과 TP의 상관계수는 0.10, 0.56으로 나타났다. COD의 상관계수는 0.63으로 TSS와 COD, TP에 대한 예측이 된 것으로 분석되었다. 딥러닝을 통한 LID 시설 내 농도변화 예측시 강우시 센서데이터 값은 조밀해야하며 오염물질 농도와 상관성이 높은 항목들에 대해 계측과 실강우 모니터링 자료를 축적하여 미래에 대한 활용성을 높여야 한다.

• Journal of The Korean Society of Agricultural Engineers
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• v.54 no.4
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• pp.9-17
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• 2012

This study was aimed to characterize non-point source (NPS) pollutant runoff and estimate event mean concentrations (EMCs) from a small rural watershed located at the headwater area of the Gyeongan stream. The study watershed consists of the two major landuse, forest (72 %) and paddy field (28 %). The nine rainfall events ranging from 18.5 to 192.6 mm in amount were monitored in this study. Stream flow was measured at the watershed outlet using a water level gauge, while a number of water samples for each event were collected and analysed for water quality. Event pollutant loads varied greatly depending on rainfall events varying from 22.6 to 3,134.2 mg/L, 0.32 to 24.56 mg/L, 0.090 to 1.320 mg/L, and 2.3 to 149.8 mg/L for SS, TN, TP, and COD, correspondently. The respective mean EMCs were estimated by 104.2, 1.00, 0.168, and 7.9 mg/L. The Pearson correlation analysis showed that COD EMC was significantly correlated with those of SS, TN, and TP. Rainfall runoff ratio appeared to be negatively correlated with EMCs of SS, TP, and COD, although not statistically significant. The event loads from the largest rainfall was greater than the sum of those from the remaining eight events. The study results suggest that the appropriate management of intensified storm events are of greater importance in curbing NPS loads, while the estimated EMCs provide base data for the unit pollutant loads determination for the forest-paddy composite upstream watershed.

• Bulletin of the Korean Chemical Society
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• v.24 no.8
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• pp.1150-1154
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• 2003

The reactions of [Ni(L)(H₂O)₂]Cl₂ (L = 2,5,9,12-tetramethyl-1,4,8,11-tetraazacyclotetradecane) with terephtalate (tp) and 2,5-pyridinedicarboxylate (pdc) generate one-dimensional nickel(II) complexes, [Ni(L)(H₂O)₂](tp) · ₄H₂O (1) and [Ni(L)(H₂O)₂](pdc)·₄H₂O (2). The structures have been characterized by X-ray crystallography, magnetic susceptibility and spectroscopy. The crystal structures of 1 and 2 show a distorted octahedral coordination geometry around the Ni(II) ion, with secondary amines of the macrocycle and two water molecules at the trans position. Complexes 1 and 2 display the one-dimensional hydrogen-bonded infinite chains. The magnetic behavior of all compounds exhibits weak interchain antiferromagnetic interactions with J values of -1.09(3) for 1 and -1.14(2) cm-1 for 2.

• Journal of The Korean Society of Agricultural Engineers
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• v.49 no.2
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• pp.99-108
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• 2007

The purpose of this study was to investigate characteristics of concentrations of pollutants such as TN (Total Nitrogen), TP (Total Phosphorus) and COD (Chemical Oxygen Demand) in outflow from a nonpoint source dominated watershed ($6.7km^2$). Regular flow measurement and water sampling were taken at five-day intervals during two years (February 2002 to January 2004) in the Ingyeong River, a tributary of the Han River. The mean concentrations of pollutants during rainy days were significantly (p<0.05) higher than those during dry days. For dry days, the flow-weighted mean concentration (0.06 mg/L) of TP during paddy irrigation periods were higher than that (0.02 mg/L) during non-irrigation periods. The seasonal mean concentration of TN was highest in spring likely due to nitrogen fertilization, but those of TP and COD were highest in summer due to particulate phosphorus and sediment-associated organic matter caused by increased discharge. The pollutant concentrations significantly increased with discharge, suggesting that the measures to reduce the increase in the concentrations during storms are needed to control nonpoint source pollution.

• Environmental Engineering Research
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• v.23 no.4
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• pp.364-373
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• 2018

The present study assessed the efficient removal of nutrients and Chlorophyll-a (Chl-a) by using methyl esterified sericite (MES) and pine needle extracts (PNE), a low cost and abundant green hybrid material from nature. For this purpose, the optimal conditions were investigated, such as the pH, temperature, MES and PNE ratio, and MES-PNE dose. In addition, a Microcystis aeruginosa control using MES-PNE was also analyzed with various inhibition models. The removal of the nutrient and Chl-a onto MES-PNE was optimized for over 95% removal as follows: 2-2.5 for the MES-PNE ratio, 7-8 pH and a $22-25^{\circ}C$ temperature. In this respect, approximately 1.52-2.20 g/L of MES-PNE was required to remove each 1 g of dry weight/L of Chl-a. Total phosphorus (TP) has a greater influence on the increase in Chl-a than total nitrogen (TN) according to the correlation between TN, TP and Chl-a. Moreover, the Luong model was the best model for fitting the biodegradation kinetics data from Chl-a on MES-PNE from lake water. The novel hybrid material MES-PNE was very effective at removing TN, TP and Chl-a from the lake and can be applied in the field.

• International Journal of Highway Engineering
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• v.12 no.4
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• pp.131-137
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• 2010

The stormwater runoff from rest areas in highways are known as more polluted compared to highways because of more vehicle activities. This study is performed to find pollutant characteristics in the rest areas in the magnitude of statistical pollutant concentrations during storms. Washoff characteristics of pollutants from rest areas by monitoring of rainfall, runoff rate and runoff samples were evaluated. High concentrations of pollutants in runoff were observed at the beginning of runoff and rapid decrease thereafter, indicating that first-flush effects are clearly occurred. Event Mean Concentrations(EMCs) of TSS, COD, TN, and TP are estimated to be in the range of 31.04-127.11mg/L, 35.5-369.5mg/L, 2.62-9.86 mg/L, and 0.53-1.96mg/L, respectively. Heavy metals in runoff showed relatively high values, possibly due to the abrasion of brake pad or tire while cars are slowly moving for parking. EMCs of total Pb, total Cu, and total Ni are in the range of $1206-16293{\mu}g/L$, $237-7906{\mu}g/L$, and $53-6372{\mu}g/L$, respectively. Pollutant loading per rest area calculated by using EMC, flowrate and target area is also described for each pollutant.

• Korean Journal of Ecology and Environment
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• v.33 no.3 s.91
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• pp.222-229
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• 2000

Spatial and temporal variation of phosphorus in response to intensity of summer monsoon was evaluated in Taechung Reservoir during 1993${\sim}$1994. Total phosphorus (TP) averaged 31 ${\mu}$g/l during the study and varied from 6 to 197 ${\mu}$g/l. Concentrations of TP were highest in the headwaters during the monsoon of July${\sim}$August 1993, and these values were mainly made of particulate P and were closely associated (R$^{2}$=0.74, p<0.001) with high inorganic suspended solids (NVSS). In-lake TP in the headwaters was mainly influenced by the watershed runoff and declined toward the dam. Values of TP downlake was only one-fifth of the peak in the headwaters and had no correlation with NVSS. In 1994, inlake TP was markedly lower relative to 1993 and showed low spatial and temporal variation. Maximum TP during monsoon 1994 in the headwaters and mid-lake was 72% and 52% lower, respectively, than in those two zones in 1993 whereas TP downlake was similar between the two years. These results suggest that temporal variation downlake is much less influenced by seasonal inflow compared to the haedwaters. In 1993, mean TP before fall overturn, based on average value for all sites, was significantly (t=5.99, p<0.001) greater than the mean after fall overturn, whereas in 1994 mean TP after fall overturn (32 ${\mu}$g/l) was greater. This outcome indicates that in 1993 major P-input originated from the external source from the watershed during the intense monsoon, whereas in 1994 internal processes dominated during the weak monsoon. Overall data suggest that annual budget of inlake P is regulated by intensity of the summer monsoon, and phosphorus data measured at single site near the dam or headwater zone may not be represent seasonal trends of the system due to large spatial variation of Taechung Reservoir.

• Journal of Environmental Impact Assessment
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• v.28 no.5
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• pp.471-482
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• 2019

Water treatment system filled with Bio-stone Ball (BSB) have been developed for the purification of polluted water in many rivers and lakes. The real-scale plants of BSB water treatment system was constructed for field application test and water purification evaluation in Maewha reservoir. The average water purification efficiencies of BSB watertreatment system shows BOD 70.3% (47.2~97.4%), COD 45.3% (26.1~64.7%), TOC 19.2% (8.5~50.0%), SS 82.8% (73.1~92.7%), Chl-a 80.4% (57.2~91.8%), TN 23.2% (6.4~39.5%), and TP 51.8% (-1.1~80.1%). BSB water treatment system shows very high at 70~80% in the water purification efficiencies of BOD, Chl-a, and SS. The average of pollution loading reduction by installation of BSB treatment system shows 39.2% for COD and 16.8% for TP. The water quality improvement rates (%) of the Maewha reservoir shows TOC 14.5%, COD 14.5%, Chl-a 12.5% and TP 25.1%. The BSB watertreatment system can be applied to many agricultural reservoirs and major rivers to deal with serious water pollution issues.

• Microbiology and Biotechnology Letters
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• v.16 no.5
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• pp.407-412
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• 1988

In order to increase the tryptophan productivity of E. coli SB1007, a mutant resistant to sulfanilamide was isolated and then a tyrosine auxotroph TY-90 was derived from the sulfanilamide-resistant mutant SA3-39-16. In the test-tube culture a quantitative amount of tryptophan was accumulated in strain TY-90 but in a jar fermentor culture the productivity was lower as compared to the level obtained by the parent strain. From the double auxotrophic mutant SB2756, a revertant resistant to 2, 000$\mu\textrm{g}$/$m\ell$ of $\beta$-thienylalanine, TA 40-10, was selected and then phenylalanine auxotrophs were derived from the revertant strain TA-40-10. One of the phenylalanine auxotrophs, TP-4, accumulated 3.7g/$\ell$ of L-tryptophan after 71-hr cultivation in a jar fermentor experiment.