• 한국환경과학회지
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• 제32권7호
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• pp.483-492
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• 2023

In this study, the treatment of livestock wastewater using an aerobic granular sludge based sequencing batch reactor was investigated. The reactor operation was carried out by general injection and split injection methods. The average removal efficiency of organic matter after the adaptation period was 71.5 and 87.4%, respectively. Some untreated organic matter was attributed to recalcitrant organic matter. The average removal efficiency of total nitrogen was 65.6 and 88.4%, respectively. These results indicate that the denitrification reaction by split injection was carried out smoothly. As for the solids, the ratio of aerobic granular sludge/mixed liquor suspended solid can be determined as the main factor of the process operation, and the ratio increased gradually and finally reached 86.0%. Correspondingly, the sludge volume index (SVI) was also improved, reaching 54 mL/g at the end of operation, and it is believed that the application of a short settling time contributed to the improvement of settleability.

• 한국대기환경학회지
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• 제7권1호
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• pp.17-22
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• 1991

Total suspended particulates (TSP) in the atmosphere was collected and size-fractionated by Andersen high volume air sampler for one year (Mar. 1987 $\sim$ Feb. 1988) in Seoul. The concentrations of several polycyclic aromatic hydrocarbons and heavy metals were determined to investigate the atmospheric concentrations, seasonal variations and its relationship with the size distribution of suspended particulate matter. The arithmetic mean concentration of total suspended particulates was 200.44 $\mug/m^3$. The concentrations of heavy metals were 2433.80 for Fe, 629.49 for Zn, 600.71 for Pb, 143.87 for Cu, and 107.21 $ng/m^3$ for Mn, respectively. The concentrations of PAHs were 3.83 for benzo(a) pyrene, 2.95 for benzo(k)fluoranthene, and 4.42 $ng/m^3$ for benzo(ghi)perylene, respectively. PAHs, Pb and Zn abounded in particles below 2.0 $\mu$m, while Fe and Mn aboounded in particles above 2.0 $\mu$m. TSP and its chemical compositions showed the seasonal variations. The concentrations of anthrophogenic pollutants like TSP, PAHs and heavy metals in the fine particles were highest in winter and lowest in summer. PAHs and Pb analyzed showed significant correlations between each other and between TSP concentration in fine particles, indicating that the particles in which they are contained have a similar behavior in the atmosphere.

• 한국대기환경학회지
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• 제8권3호
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• pp.179-190
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• 1992

This study was carried out to characterize sources of atmospheric total suspended particulates (TSP) in urban and sub--urban areas of metropolitan taegu. The sources were tentatively identified by a multivariate technique, i.e. principal component analysis (PCA), and the source contributions to the atmospheric concentrations of TSP were further estimated by stepwise multiple regression analysis. A total of 5 sources was identified in the urban area of Taegu (soil dust resuspension, fuel combustion, secondary aerosol, traffic related aerosol, and refuge burning), while 4 sources were found to be significant in the sub--urban area as following: fuel combustion/secondary aerosol, soil dust resuspension, traffic related aerosol, and wood/agricultural burning. The largest contributor to the atmospheric TSP appeared to be the soil dust resuspension in both areas. The source apportionment of the extractable organic matter (EOM) was also carried out for the Taegu data. The EOM was determined with respect to the solvent polarity, i.e. cyclohexane (non-polar), dichloromethane (semi--polar), and acetone (polar). In addition, the source profiles for the TSP in Taegu area were estimated using a PCA-based algorithm, and the validity was evaluated tentatively by comparing the data in the literature.

• 한국농공학회지
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• 제45권2호
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• pp.126-137
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• 2003

The feasibility study of UV-disinfection system was performed for disinfection of effluent from wastewater treatment plant. Three low-pressure UV lamps of 17, 25, and 41 W were examined with various flow rates. Low-pressure UV lamps of 17W were examined with various turbidity, DOM (dissolved organic matter), and SS (suspended solid). The pilot plant was a flow-through type UV-disinfection system, and the range of exposure time varied from 5 to 40 seconds, turbidity from 0 to 40 NTU, DOM from 0 to 30 mg/L, and SS from 10 to 40 mg/L. The 41W lamp demonstrated complete disinfection showing no survival ratio in all the experimental conditions, and generally 17W and 25W lamps also showed high removal ratio over 97%. For the same UV dose (UV intensity times exposure time), high intensity-short exposure conditions showed better disinfection efficiency than low intensity-long exposure conditions. While the effects of turbidity and DOM were not apparent, the effects of SS was significant on the disinfection efficiency which indicates that SS control before UV-disinfection appears to be necessary to increase removal efficiency. Considering characteristics of effluent from existing wastewater treatment plants, cost-effectiveness, stable performance, and minimum maintenance, the flow-through type UV-disinfection system with high intensity and low-pressure lamps was thought to be a competitive disinfection system for wastewater reclamation.

• 한국물환경학회지
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• 제22권1호
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• pp.7-16
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• 2006

The present study evaluated effect of temperature on removals of organic matter (C), nitrogen (N) and phosphorus (P) in Modified-Dephanox (M-Dephanox) process, which is hybrid system, comparing with those of Modified-Ludzack Ettinger (MLE) under the suspended-growth bacteria, as control. M-Dephanox process was more stable than MLE process in the removal of C, N, P, especially in nitrification, as the temperature was decreased from $25^{\circ}C$ to $16^{\circ}C$. As the temperature was decreased from $25^{\circ}C$ to $16^{\circ}C$, the removal efficiency of $NH_4{^+}-N$ of M-Dephanox process was decreased by 3.8%, but that of MLE process decreased by 25.7%. T-N removal efficiency of M-Dephanox was higher than MLE process by 27.1% and 26.9% at $25^{\circ}C$ and $16^{\circ}C$ of temperature, respectively.

• 한국환경과학회지
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• 제8권1호
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• pp.51-59
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• 1999

Chemical composition of atmospheric aerosols was measured at 4 sites in Pusan. All the samples were collected with a high volume air sampler from January to October 1996, to analyze major ions and heavy metals. Dominant ions of aerosols were S $O_4$$^{2-}$ in anion and N $a^{+}$ in cation. Sulfate, nitrate and ammonium ions in aerosols showed high enrichment factor to soil and seawater composition. The concentrations of heavy metals in aerosols was lowest at the site PI near the coast. The lowest concentrations of major ions and heavy metals mainly appeared in August, probably due to scavenging by frequent rains. Especially, the concentrations of total suspended particulate matter(TSP) and heavy metals in aerosols showed good correlations in Pusan. Based on crustal Al, enrichment factors for some metals(Zn, Cu, Pb, Cd) in aerosols were significantly greater than unity, and the order was Cd ＞ Pb ＞ Zn ＞ Cu. This evidence suggests that Cd and Pb are derived predominantly from non-crustal sources.s.

• 환경생물
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• 제27권3호
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• pp.279-284
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• 2009

In order to understand food sources-metabolism for the pacific oyster (Crassostrea gigas), the stable isotope ratios of carbon (${\delta}^{13}C$) and nitrogen (${\delta}^{15}N$) of its gut, gill, and muscle as well as potential food sources (particulate organic matter, sedimentary organic matter, benthic microalgae, seagrass detritus) were determined in Dongdae Bay. Average ${\delta}^{13}C$ and ${\delta}^{15}N$ values reflect that oysters primarily fed on sedimentary organic matter as opposed to suspended organic matter during summer and winter seasons. However, the relatively enriched $^{15}N$ values of particulate organic matter (>$250{\mu}m$) and sedimentary organic matter in the summer may be due to the photosynthetic incorporation of $^{15}N$-enriched nitrogen (DIN) or the spawning events of bivalves. Specific oyster tissues (gut, gill, and muscle) revealed different metabolic pathways, which were determined through analysis of ${\delta}^{13}C$ and ${\delta}^{15}N$ in each organ. The present results suggest the determination of carbon and nitrogen stable isotopes to be a useful approach in ecological research related to the food sources- metabolism of Crassostrea gigas.

• 한국대기환경학회지
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• 제20권6호
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• pp.715-727
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• 2004

This study was carried out to evaluate non-smoker's exposure levels to environmental tobacco smoke (ETS) in the air of offices in urban areas. A total of 65 offices were selected from two large cities, i.e. Daegu and Daejeon. The field sampling was conducted repeatedly in summer (1999) and winter (1999～2000). The measured ETS markers included respirable suspended particles (RSP as PM$_{40}$ ), vapor and particulate phase ETS markers, including nicotine, 3-ethnyl pyridine (3-EP), ultraviolet absorbing particulate matter (UVPM), fluorescing particulate matter (FPM), and solanseol in ETS particles (SolPM). RSP was measured gravimetrically by a microbalance. The particle samples were then used for the determination of particulate ETS markers by HPLC, while vapor phase markers determined by GC/NPD. The analytical methods were validated for repeatability, linearity, detection limits, and duplication precision. The concentrations of RSP and other ETS markers were significantly higher in smoking offices than non-smoking offices. Despite the similar smoking strength in each office for different seasons, the concentration levels of ETS components appeared to be higher in winter than summer. The contributions of ETS to RSP concentrations based on SolPM, FPM, and UVPM methods were estimated to be in the range of 15.2 ～ 25.3% in smoking offices, whereas 2.4 ～ 15.9% in non-smoking offices. The cooling and heating types did not affect significantly the concentrations of RSP and other ETS markers. Finally, further research issues were suggested to obtain more scientific information on the non-smoker's exposure to ETS with respect to the frame of risk assessment..

• 대한원격탐사학회지
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• 제39권5_1호
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• pp.695-713
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• 2023

연안 해역에서 식물성플랑크톤, 부유입자, 용존유기물은 복합적이고 비선형적으로 해수반사도를 변화시킨다. 최근 빠르게 발전하는 신경망 기술은 복잡한 비선형 관계를 효과적으로 처리할 수 있는 장점이 있다. 기존 연구에서는 성분별 고유광특성을 도출하기 위하여 세 단계의 신경망을 구성하였으나 본 연구에서는 심층신경망을 직접 적용하는 알고리즘을 제안하였다. 본 연구에서 활용한 데이터세트는 국제해색조정그룹에서 제공하는 합성데이터를 활용하였으며, 입력데이터는 9개의 파장의 원격반사도를 입력하였다. 이를 통해 해수 고유광특성을 심층신경망을 기반으로 도출하였다. 성능을 평가하기 위해 준분석 알고리즘(quasi-analytical algorithm)과 비교하였으며, 데이터 분포에 따른 로그 변환 여부가 심층신경망 알고리즘의 성능에 영향을 미치는 정도를 비교 분석하였다. 그 결과, 준분석 알고리즘보다 심층신경망 알고리즘을 활용하면 부유입자에 대한 흡광계수를 제외한 고유광특성을 정확하게 추정할 수 있으며(R² 0.9 이상), 부유입자와 용존유기물의 흡광계수를 부유입자와 용존유기물 흡광계수로 각각 분리할 수 있었다. 그리고 심층신경망을 직접적으로 적용하는 알고리즘은 데이터의 로그 변환을 하지 않아도 성능 차이가 거의 없음을 파악할 수 있었다. 이 연구 결과를 해색 자료 처리에 실제 적용하기 위해서는 다양한 해역의 현장자료 및 추가적인 데이터 세트를 활용한 학습을 진행하여, 경험적 및 반분석적 방법과 비교 분석하고 알고리즘 간 장단점을 적절히 파악하는 연구가 필요하다.

• Journal of Preventive Medicine and Public Health
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• 제33권3호
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• pp.306-312
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• 2000

Background : Polycyclic aromatic hydrocarbons (PAH) are well known environmental pollutants. The measurement of PAH in ambient air is not commonly used, because it is quite difficult to perform and is unreliable. Using biomarkers of PAH can be an alternative approach to this problem. The PAH in ambient air is absorbed in particulate matter. Total suspended particulate(TSP) or particulate matter of less than $10{\mu}m$ in diameter (PM10) can be easily measured. Therefore, TSP or PM10 can be used as a surrogate measurements of ambient air PAH. Objectives : We investigated whether the urinary concentration of two biomarkers of PAH, 1-hydroxypyrene (1-OHP) and 2-naphthol, could reflect the total suspended particulate in the general population. Methods : In order to exclude the effects of occupational exposure and smoking, first grade middle school students were included in this study. Four middle schools within a one kilometer boundary of ambient air monitoring stations were selected. Total suspended particulate was regarded as the marker of airborne PAH. Diet and smoking data were collected by self administered questionnaires, and spot urine samples were collected. Urinary 1-OHP and 2-naphthol were analyzed by high performance liquid chromatography. Results : The correlation between urinary 1-OHP, 2-naphthol and passive smoking was not statistically significant. The correlation between urinary 1-OHP and TSP indices was not statistically significant. The correlations between urinary 2-naphthol and TSP of two lag days, one lag day, and zero lag days were statistically significant. The statistical significance of two lag days was the strongest (p=0.001), one lag day was the next (p=0.0275), and zero lag days was the weakest (p=0.0349). Conclusion : Our results imply that the urinary concentration of 2-naphthol can be applied as a PAH exposure marker for the general population with low PAH exposure.