• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.48 no.5
• /
• pp.285-295
• /
• 1999

Electroluminescent(EL) devices based on organic materials have been of great interest due to their possible applications for large-area flat-panel displays. They are attractive because of their capability of multi-color emission, and low operation voltage. An approach to realize such device characteristics is to use active layers of lanthanide complexes with their inherent extremely sharp emission bands in stead of commonly known organic dyes. In general, organic molecular compounds show emission due to their $\pi$-$\pi*$ transitions resulting in luminescence bandwidths of about 80 to 100nm. Spin statistic estimations lead to an internal quantum efficiency of dye-based EL devices limited to 25%. On the contrary, the fluorescence of lanthanide complexes is based on an intramolecular energy transfer from the triplet of the organic ligand to the 4f energy states of the ion. Therefore, theoretical internal quantum efficiency is principally not limited. In this study, Powders of TPD, $Eu(TTA)_3(phen) and AlQ_3$ in a boat were subsequently heated to their sublimation temperatures to obtain the growth rates of 0.2~0.3nm/s. Organic electrolumnescent devices(OELD) with a structure of $glass substrate/ITO/Eu(TTA)_3(phen)/AI, glass substrate/ITO/TPD/Eu(TTA)_3(phen)/AI and glass substrate/ITO/TPD/Eu(TTA)_3(phen)/AIQ_3AI$ structures were fabricated by vacuum evaporation method, where aromatic diamine(TPD) was used as a hole transporting material, $Eu(TTA)_3(phen)$ as an emitting material, and Tris(8-hydroxyquinoline)Aluminum$(AlQ_3)$ as an electron transporting layer. Electroluminescent(EL) and current density-voltage(J-V) characteristics of these OELDs with various thickness of $Eu(TTA)_3(phen)$ layer were investigated. The triple-layer structure devices show the red EL spectrum at the wavelength of 613nm, which is almost the same as the photoluminescent(PL) spectrum of $Eu(TTA)_3(phen)$.It was found from the J-V characteristics of these devices that the current density is not dependent on the applied field, but on the electric field.

• Resources Recycling
• /
• v.14 no.1
• /
• pp.17-25
• /
• 2005

In order to recover valuable metals from the waste electronic scrap, bioleaching of Cu, Zn, Al, Co, Ni, Sn and Pb was carried out using Thiobacillus ferrooxidans as a leaching microorganism in a shaking flask. In a preliminary study, to obtain the data on the leaching of Cu, Zn, Al, Co and Ni, the metal leaching was accomplished using metal powers instead of electronic scrap. The leaching percentaga of Cu, Zn, Co, Al and Ni powers was reduced with the increase of metal power concentration in solution. Below the metal concentration of 0.5 g/L, more than 85% of Cu, Co and Zn powers was leached out. At the electronic scrap concentration of 100 g/L, Thiobacillus ferrooxidans were able to leach more than 90% of the available Cu and Co while Al, Zn and Ni were able to leach less than 40%. Pb and Sn were not detected in the leachate. Pb was precipitated as PbSO$_4$, whereas Sn precipitated probably as SnO.

• Journal of Aquaculture
• /
• v.21 no.4
• /
• pp.278-284
• /
• 2008

Artificially-produced juvenile black sea bream Acanthopagrus schlegeli (total length $8.3{\pm}1.0\;cm$, body weight $11.2{\pm}4.2\;g$) were released in eelgrass, Zostera marina bed and their initial food organism and changes of body compositions were investigated for one month after release. Predation rates in fish sampled on 1st and 3rd days were 79%, increased up to 100% on 7th and 10th days, and then decreased on 30th days as 75%. Major prey organisms was composed of mainly Amphipoda and Gastropoda. Ratio of Amphipoda and Gastropoda in stomach were highest in fish sampled on 15th and 1st days after release, respectively. Crustacea and Algae were maintained about 20% during a sampling period. Visceral weight index (VWI) offish sampled 20th and 30th after release were significantly higher than that of initial. Carcass crude protein and lipid contents of released fish were showed significantly decreasing; however carcass n-3 HUFA composition was showed increasing tendency with the passage of time after release. Eelgrass bed was supposed to be helpful for the released fish to adjust their feeding habits and biochemical metabolism to the natural environment within a short period after release.

• Childhood Kidney Diseases
• /
• v.21 no.2
• /
• pp.142-146
• /
• 2017

Purpose: To evaluate changes in quality of life (QoL) in patients with neurogenic bladder treated with clean intermittent catheterization (CIC), who changed from a multiple use catheter (MUC) to single use catheter (SUC). Methods: The Modified Intermittent Self-Catheterization Questionnaire (mISC-Q) was used to determine potential changes in patients' QoL as a result of switching from MUC to SUC. The mISC-Q consists of questions within four categories: ease of use, convenience, discreetness, and symptomatic benefit. Answers were graded as Strongly agree (+2), Agree (+1), Not sure (0), Disagree (-1), and Strongly disagree (-2). Overall patient QoL, as well as by sex, disease (presence of augmentation cystoplasty), and catheterization route (via urethra or urinary diversion), were analyzed. Results: Thirty-eight patients (21M:17F; mean age: $21.7{\pm}5.3y$) submitted questionnaires. For ease of use, SUC was significantly better than MUC (score: 0.364, P=0.002) in all patients. Patients with catheterization via the urethra showed significant favor for SUC in ease of use (score: 0.512, P<0.001) and convenience (score: 0.714, P=0.011), but patients with catheterization via the abdominal stoma of urinary diversion gave negative scores in all categories, though no categories were significant. Conclusion: This study suggested that changing from MUC to SUC may lead to improvements in QoL, especially regarding ease of use. This benefit was clearly found in patients with catheterization via urethra rather than abdominal stoma of urinary diversion.

• Resources Recycling
• /
• v.24 no.5
• /
• pp.33-39
• /
• 2015

A basic study was conducted to effectively recover nitric acid from a waste solder stripper by diffusion dialysis using anion exchange membranes. The effects of flow rate, flux ratio, nitrate concentration, and metallic ion types and concentration on the recovery percentage of nitric acid were investigated. The recovery percentage of nitric acid was decreased with the increase of flow velocity. But the recovery percentage of nitric acid was increased as the increase of flux ratio(W/F) and showing a recovery percentage of nitric acid of about 99% at a flux ratio of 1.5 or more. As the increase of nitric acid concentration in feed solution, the recovery percentage of nitric acid was increased up to 3.0M, but in case of greater than 3.0M, the recovery percentage gradually was decreased. Leakage percentage of metallic ions through the membrane were in the order of Pb, Na and Cu but Fe and Sn did not leakaged. As a result of diffusion dialysis using real waste solder stripper at a flow rate of $0.9L/hr-m^2$, W/F = 1.3, a recovery percentage of nitric acid of approximately 94% was gained.

• Journal of Korean Society on Water Environment
• /
• v.33 no.2
• /
• pp.203-210
• /
• 2017

This study was performed to verify the replacement of COD to TOC, which is more accurate and reliable in analysis, as the water quality pollution index and to investigate the characteristics of water quality and the correlations for organic matter, suspended solids and nutrient materials during 2012 to 2015. The oxidation rates were compared by calculating the values of BOD-C/TOC & COD-C/TOC. The average value of TOC was 3.4(1.1 ~ 8.0) mg/L at 14 sites during the period. The ratios of BOD-C/TOC and COD-C/TOC, that mean the resolvability amounts among all carbon materials, were 28.8% and 62.7%, respectively. The correlation coefficient of TOC to COD at all sites was 0.718 (p<0.01), the highest value in comparing all items. The correlation coefficient of TOC to COD at Gwangju stream was 0.753 (p<0.01), the highest compare to the values at other rivers. The correlation coefficient of TOC to COD was 0.757 (p<0.01) at all sites in the range of TP-III ($0.1{\leq}TP$) and the value was 0.762 (p<0.01) in the range of TN-II ($2.0{\leq}TN$<3.0). As a result, TOC could be used as a water pollution index of organic matter instead of COD.

• Journal of Environmental Health Sciences
• /
• v.40 no.3
• /
• pp.204-214
• /
• 2014

Objectives: Vehicular emissions are one of the main sources of air pollution in urban areas. Correlation analysis was conducted between air pollutants and traffic volume in order to identify causes of air pollution in Gwangju. Methods: Using traffic volumes and air quality monitoring data from 2002 to 2012 from nine stations (seven urban areas, two roadside areas), especially at three sites where traffic volumes were high, the correlation coefficients were obtained between air pollutants as PM-10 (particulate matter), $NO_2$, $SO_2$, CO and $O_3$ at the stations and traffic volumes near the air monitoring stations. Results: Due to traffic volume and distance between the station and the traffic road, concentrations of pollutants at roadside areas were higher than at urban areas, with the exception of $O_3$. The concentration of $O_3$ showed statistically significance with those of other gas materials as $NO_2$, $SO_2$, and CO in winter (p<0.001) and spring (p<0.05). During the period of October 7 to 20, 2012, excluding periods of yellow dust, smog and rainy season, the ratio of $NO/(NO+NO_2)$ showed the highest value 0.57 and 0.40 at Unam and Chipyeong of two roadside stations, followed by 0.35 at Nongseong with vehicular effects. The correlation coefficient between traffic volume and $O_3$, CO, $NO_2$ became higher when the data on mist and haze days were excluded, than when all hourly data were used in that period, at the three sites of Unam, Chipyeong, and Nongseong. Conclusions: Air quality showed a considerable effect from vehicles at roadside areas compared to in urban areas. Air pollutant diminishment strategies need to be aggressively adopted in order to protect atmospheric environment.

• Analytical Science and Technology
• /
• v.28 no.3
• /
• pp.246-254
• /
• 2015

From 2013 to 2014, volatile organic compounds (VOCs) were analyzed to determine biogenic volatile organic compounds (BVOCs) and anthropogenic volatile organic compounds (AVOCs) at eight sites in Mt. Mudeung and one site in downtown, by using a GC/Mass-ATD (automatic thermal desorber). The concentration of terpene noted as biogenic volatile organic compounds at Pungamjeong (PA), in a forest of Chamaecyparis obtusa, was 821 pptv, which was the highest among the eight sites. This value was followed by Wonhyogyegok (WH: 785 pptv), Norritzae (NZ, coniferous forest: 679 pptv), Dongjeokgol (DJ, mixed species forest: 513 pptv), Jangbuljae (JB, Abies koreana: 476 pptv), and Seinbongsamgerri (SS, pine trees: 464 pptv). 11~15 species of terpene was detected in the forest depending on the site. At PA in May, α-pinene showed the highest value, occupied 20% of terpene followed by coumarin, sabinene, phellandrene, myrcene, borneol, eucalyptol, β-pinene, cymene, δ-limonene, γ-terpinene, camphor, camphene, and mentol in the order. The mean concentrations of AVOCs were 0.74~2.52 ppbv in the forests and 3.14 ppbv in the downtown area. From May to July, the AVOCs ratios of the downtown to each forest were 1.9~4.0. Among 10 species of AVOCs, the sum of toluene and benzene was 2.34 ppbv and occupied 75%. In June, the ratios of toluene were 44.1% at DJ site and 53.1% at JW site (downtown). The BVOCs showed a positive correlation with the AVOCs at the forest sites (r = 0.328), which was statistically insignificant (p = 0.184).