• Journal of Korean Society of Environmental Engineers
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• v.29 no.5
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• pp.548-555
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• 2007

The control of wastewater treatment has two merits; one is to regulate water quality of effluent and the other is to reduce the cost of wastewater treatment. The purpose of this study was to control the ammonium nitrogen in effluent that is known to cause eutrophication. The control was based on simplified ASM No. 1 which had 3 component materials and 8 coefficients, and the control method was as following. Firstly the ammonium concentration of inflow was measured and the optimal aeration time in effluent was determined according to simplified ASM No. 1 to be 1.0 mg/L. If ammonium concentration of effluent was not equal to 1.0 mg/L, the influent ammonium was corrected by adaptive control. These processes above were repeatedly performed. The SBR running aerobic-anoxic phase had been controlled for 1 month with this method. As a result, the ammonium concentration of the effluent showed in the range of $0.22\sim3.1$ mg/L with an average concentration of 1.1 mg/L. The adaptive control method used in this study was found very useful to control and predict the effluent concentration of ammonium.

• Journal of Life Science
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• v.25 no.9
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• pp.1027-1035
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• 2015

A strain GP32 which produces a highly viscous extracellular polysaccharide was conducted with soil samples and identified as Pseudomonas species. The culture flask conditions for the production of extracellular polysaccharide by Pseudomonas sp. GP32 were investigated. The most suitable carbon and nitrogen source for extracellular polysaccharide production were galactose and (NH₄)₂SO₄. The optimum carbon/nitrogen ratio for the production of extracellular polysaccharide was around 50. The optimum pH and temperature for extracellular polysaccharide production was 7.5 and 32℃, respectively. In batch fermentation using a jar fermentor, the highest extracellular polysaccharide content (15.7 g/l) was obtained after 70 hr of cultivation. The extracellular polysaccharide produced by Pseudomonas sp. GP32 (designated Biopol32) was purified by ethanol precipitation, cetylpyridinium chloride (CPC) precipitation, and gel permeation chromatography. Biopol32, which has an estimated molecular weight of over 3×10⁷ datons, is a novel polysaccharide derived from sugar components consisting of galactose, glucose, gulcouronic acid and galactouronic acid in an approximate molar ratio of 1.85 : 3.24 : 1.00 : 1.42. The solution of Biopol32 showed non-Newtonian characteristics. The viscosity of Biopol32 exhibited appeared to be higher at all concentration compared to that of zooglan from Zoogloea ramigera. An analysis of the flocculating efficiency of Biopol32 in industry wastewater (food, textile, and paper wastewater) revealed chemical oxygen demand (COD) reduction rates 58.4-67.3% and suspended solid (SS) removal rates 82.6-91.3%. Based on these results, Biopol32 is a possible candidate for industrial applications such as wastewater treatment.

• Korean Journal of Environmental Agriculture
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• v.24 no.3
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• pp.253-260
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• 2005

Salt accumulation in the plastic film house soils under continuous cultivation condition causes problems such as salt damages to plants, nitrate accumulation in vegetables, groundwater contamination, etc. due to excess application of fertilizers. Objective of this research was to find an optimum adsorbent to reduce salt concentration in the soil solution of plastic film house soils, where crop injuries have been observed due to the salt accumulation. The soils were significantly high in available P $(1,431{\sim}6,516mg\;kg^{-1}),\;NO_3-N\;(117.60{\sim}395.73mg\;kg^{-1})$, exchangeable Ca $(4.06{\sim}11.07\;cmol_c\;kg^{-1})$ and Mg $(2.59{\sim}18.76\;cmol_c\;kg^{-1})$, as compared to those of the average upland soils in Korea. Soils were treated with each of adsorbent such as ion-exchange resin, zeolite, rice bran, etc. at 2% level and prepared into saturated-paste samples. After equilibrium, soil solution was vacuum-extracted from the soil and measured for changes of the pH, EC, and concentrations of $Ca^{2+},\;Mg^{2+},\;K^+,\;Na^+,\;{NH_4}^+,\;{PO_4}^{3-}\;and\;{NO_3}^-$. Rice bran effectively removed ${PO_4}^{3-}\;and\;{NO_3}^-$ in the soil solution up to 100%. Efficiency was decreased in the orders of rice bran > ion-exchange resin > zeolite. Removal efficiencies of zeolite and ion-exchange resin for $Ca^{2+}$ were ranged from 1 to 65% and from 7 to 61%, respectively. Ion-exchange resin was also effective for removing $Mg^{2+},\;K^+,\;Na^+,\;and\;{NH_4}^+$. Overall results demonstrated that rice bran and ion-exchange resin could be applicable for salt accumulated soil to remove the respective anion and cation.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.9
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• pp.939-947
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• 2008

PCR-DGGE method was applied to analyze changes of microbial community in simultaneous nitrification and denitrification (SND) bioreactor with various DO concentrations. In the analysis of eubacterial community, band profiles of DGGE were similar with 2 or 1 mg/L DO concentrations in the reactor. Experimental results led to 16 different bacteria being identified, including 5 dominant strains(3 strains of Uncultured Bacterium, 1 strains of Bacillus, 1 strains of Uncultured Bacteroidetes). DGGE results at 0.5 mg/L DO concentration led to 12 strains being identified, including 7 dominant strains(5 strains of Uncultured Bacterium, 2 strains of Zoogloea sp.). DGGE results at 0.1 mg/L DO concentration led to 11 strains being identified, including 3 dominant strains(1 strains of Uncultured Bacterium, 2 strains of Zoogloea sp.). In DGGE band profiles of $\beta$-AOB($\beta$-Ammonia Oxidizing Bacteria), only one band was observed. This band had 97% similarity with Nitrosomonas sp. done DNB Y20. This band was clearly observed at the 2, 1 and 0.5 mg/L DO concentrations, while the brightness of the band at 0.1 mg/L DO concentration was mostly dimmed. In DGGE band profiles of denitrification process, 5 bands(3 strains of Uncultured organism containing nirS, 2 strains of Uncultured organism containing nirK) were observed. Among those bands, the brightness of one band was gradually increased at the lower DO concentrations. This band has 86% identity with Uncultured organism clone eS1 cd1 nirS gene, partial cds. Based on this result, it could be concluded that Uncultured organism clone eS1 cd1 nirS gene, partial cds is a predominant microorganism in the denitrification process.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.247-251
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• 2004

반도체 소자의 제조에 있어 실리콘 표면에 성장한 자연산화막을 제거하기 위해 일반적으로 습식 세정 기술이 이용되어 왔다. 하지만 소자의 최소 선폭(design rule)이 nano급으로 고집적화 됨에 따라 contact hole 바닥의 자연산화막을 깨끗이 제거하는데 있어서 그 한계를 나타나고 있다. 이에 대한 효과적인 대안 공정으로 가스 건식 세정 기술이 연구되고 있다. 본 논문에서는 한 번에 50매 이상의 웨이퍼를 처리함으로써 생산성 측면에서 월등한 배치식 설비에서 원거리 플라즈마(remote plasma) 장치에서 2.450Hz의 마이크로웨이브(${\mu}$-wave)에 의해 형성시킨 수소라디칼과 $NF_3$ 가스를 이용하여 실리콘에 결함을 주지 않고 자연산화막을 선택적으로 제거하는 공정에 대해 고찰하였다. AFM을 이용한 표면분석, TEM을 이용한 물성분석, 그리고 ToF-SIMS 및 XPS를 이용한 화학 분석을 습식 및 건식 세정을 비교 평가한 결과, 건식 세정 공정이 실리콘 표면에 결함을 주지 않고 자연산화막을 제거 할 수 있음을 확인하였다. 산화막$(SiO_2)$, 질화막$(Si_3N_4)$, 그리고 다결정 실리콘(Poly-Si) 등의 각 막질별 식각 특성을 고찰하였으며, $NH_3$의 캐리어 가스인 $N_2$의 주입량을 조절함으로써 수소라디칼 형성 효율의 개선이 가능하였으며, 이로부터 게이트와 소스/드레인 사이를 절연하기 위해 이용되는 질화막의 식각 선택비를 2배 정도 개선할 수 있었다. nano급 소자에 실장하여 평가한 결과에서 불산(HF)에 의한 습식 세정 방식에 비하여 약 $20{\sim}50%$ 정도의 contact 저항 감소 효과가 있음이 확인되었다.두 소자 모두 $40mA/cm^2$ 에서 이상적인 화이트 발란스와 같은(0.33,0.33)의 색좌표를 보였다.epsilon}_0=1345$의 빼어난 압전 및 유전특성과 $330^{\circ}C$의 높은 $T_c$를 보였고 그 조성의 vibration velocity는 약4.5 m/s로 나타났다.한 관심이 높아지고 있다. 그러나 고 자장 영상에서의 rf field 에 의한 SAR 증가는 중요한 제한 요소로 부각되고 있다. 나선주사영상은 SAR 문제가 근원적으로 발생하지 않고, EPI에 비하여 하드웨어 요구 조건이 낮아 고 자장에서의 고속영상방법으로 적합하다. 본 논문에서는 고차 shimming 을 통하여 불균일도를 개선하고, single shot 과 interleaving 을 적용한 multi-shot 나선주사영상 기법으로 $100{\times}100$에서 $256{\times}256$의 고해상도 영상을 얻어 고 자장에서 초고속영상기법으로 다양한 적용 가능성을 보였다. 연구에서 연구된 $[^{18}F]F_2$가스는 친핵성 치환반응으로 방사성동위원소를 도입하기 어려운 다양한 방사성의 약품개발에 유용하게 이용될 수 있을 것이다.었으나 움직임 보정 후 영상을 이용하여 비교한 경우, 결합능 변화가 선조체 영역에서 국한되어 나타나며 그 유의성이 움직임 보정 전에 비하여 낮음을 알 수 있었다. 결론: 뇌활성화 과제 수행시에 동반되는 피험자의 머리 움직임에 의하여 도파민 유리가 과대평가되었으며 이는 이 연구에서 제안한 영상정합을 이용한 움직임 보정기법에 의해서 개선되었다. 답이 없는 문제, 문제 만들기, 일반화가 가능한 문제 등으로 보고, 수학적 창의성 중 특히 확산적 사고에 초점을 맞추어 개방형 문제가 확

• Korean Journal of Environmental Agriculture
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• v.42 no.1
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• pp.52-62
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• 2023

This study focused on determining the specific causes and prevention methods of mass fish deaths occurred in five reservoirs (Gagugi, Neupgokgi, Danggokgi, Sagokji, and Hangokji) in Andong-si. For this purpose, a survey of agricultural land and livestock in the upper part of the reservoirs and analysis of water quality in the reservoir irrespective of whether it rains or not were conducted. We attempted to examine the changes in dissolved oxygen (DO) in the surface and bottom layers of reservoirs and changes in DO depending on the amount of livestock compost and time. Based on the above investigations, treatment plans were established to efficiently control the inflow of contaminated water into reservoirs. The rainfall and farmland areas in the upper part of the reservoir were investigated using Google and aviation data provided by the Ministry of Land, Infrastructure, and Transport. The current status of livestock farms distributed around the reservoirs was also examined because compost from these farms can flow into the reservoir when it rains. Various water quality parameters, such as phosphate phosphorus (PO₄-P) and ammonium nitrogen (NH₃-N), were analyzed and compared for each reservoir during the rainy season. Changes in the DO concentration and electrical conductivity (EC) were also observed at the inlet of the reservoir during raining using an automated instrument. In addition, DO was measured until the concentration reached 0 ppm in 10 min by adding livestock compost at various concentrations (0.05%, 0.1%, 0.3%, and 0.5% by wt.), where the concentration of the livestock compost represents the relative weight of rainwater. The DO concentration in the surface layer of reservoirs was 3.7 to 5.3 ppm, which is sufficient for fish survival. However, the fish could not survive at the bottom layer with DO concentration of 0.0-2.1 ppm. When the livestock compost was 0.3%, DO required 10-19 h to reach 0 ppm. Considering these results, it was confirmed that the DO in the bottom layer of the reservoir could easily change to an anaerobic state within 24 h when the livestock compost in the rainwater exceeds 0.3%. The results show that the direct cause of fish mortality is the inflow of excessive livestock compost into reservoirs during the first rainfall in spring. All the surveyed reservoirs had relatively good topographical features for the inflow of compost generated from livestock farms. This keeps the bottom layer of the reservoir free of oxygen. Therefore, to prevent fish death due to insufficient DO in the reservoir, measures should be undertaken to limit the amount of livestock compost flowing into the reservoir within 0.3%, which has been experimentally determined. As a basic countermeasure, minerals such as limestone, dolomite, and magnesia containing calcium and magnesium should be added to the compost of livestock farms around the reservoir. These minerals have excellent pollutant removal capabilities when sprayed onto the compost. In addition, measures should be taken to prevent fish death according to the characteristics of each reservoir.

• Journal of Life Science
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• v.32 no.12
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• pp.971-978
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• 2022

Sulfur-oxidizing, ammonium-oxidizing, and nitrogen-oxidizing media were used to isolate bacteria to degrade malodor gas effectively in piggery manure or soil. Twelve different strains were isolated: Paenibacillus amylolyticus, Rhodococcus jostii, Rhodococcus qingshengii, Rhodococcus opacus, Alcaligenes faecalis, Alcaligenes faecalis, Kastia adipate, Kastia adipata, Microbacterium oxydans, Halomonas campisalis, Acinetobacter oleivorans, and Micrococcus luteus. By inoculating each strain in the piggery liquid manure by 1%, the pH in most strain treatments was maintained at 8.0. Total bacterial counts were maintained at 7.3~7.9 log CFU/ml until 15 days, and then they dropped dramatically down to 5.1~5.5 log CFU/ml. On the 30th day, the treatment group inoculated with Rhodococcus opacus SK2659 showed a relatively high level of ammonium nitrogen removal, which was 39% of that of the control group. When Rhodococcus opacus SK2659 was inoculated, H2S concentration after 100 days was 3.23% compared with the control (no inoculation), suggesting that Rhodococcus opacus SK2659 is an excellent strain for removing malodor gas. The gas production of the treatments was lower than that of the control. The total accumulated amount of gas production in most strain treatments was a quarter of the gas production compared to the control throughout the experimental periods. Acinetobacter oleivorans SK2675 showed the lowest level at 12.39% compared to the control in gas production. In conclusion, the use of mixture strains, such as Rhodococcus opacus SK2659 and Acinetobacter oleivorans SK2675 isolated in this study could increase the efficacy of malodor gas reduction in the biological treatment of piggery manure.