• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.421-421
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• 2021

도시화, 산업화로 인해 하수처리장 유입하수 내 질소 농도가 증가하면서 그에 따른 부영양화 발생, 수생태계에 독성을 미치는 등의 악영향 또한 증가하게 되었다. 하수 내 고농도 질소를 처리하기 위해 1990년 초 연구가 시작되어 현재 보편적으로 사용되고 있는 생물학적 질소 제거 공정은 산소공급과 외부탄소원 보충 과정에서 상당한 비용이 소요된다. 이와 같은 문제점이 대두됨에 따라 고도의 질소 제거 공정이 요구되면서, 경제적으로 개선이 이루어져 기존의 질산화·탈질 공정보다 효율적인 혐기성 암모늄 산화 공정(ANaerobic AMMonium OXidation, ANAMMOX)이 제안되었다. ANAMMOX 공정은 혐기성 조건 아래 전자공여체와 전자수용체로써 암모니아성 질소와 아질산성 질소를 이용해 질소가스 형태로 질소를 제거하는 공정이다. 질산화·탈질 공정과 비교했을 때, 폭기과정에서의 산소요구량 감소, 외부탄소원 불필요, 질소 제거 과정 단축 등의 장점을 가진다. 본 연구는 수처리공정에서의 ANAMMOX 공정의 적용 가능성을 확인하고, 암모니아성 질소대비 아질산성 질소 비율에 따른 Mainstream ANAMMOX 공정의 효율 비교를 통해 공정의 안정성과 높은 제거효율을 확보할 수 있는 NH₄⁺ 대비 NO₂^- 비율을 도출하는데 목적이 있다. 실험실 규모의 Mainstream ANAMMOX 반응조에 적용한 비율은 선행연구를 비롯한 화학양론식에서 제시된 비율을 바탕으로 산정하였다. 1.00부터 1.30의 전체적인 비율을 Initial과 Advanced 2개의 구간으로 나누어 운전한 결과, 각 구간의 NH₄⁺ 제거효율은 각각 58~86%, 94~99%였다. NH₄⁺ 대비 NO₂^- 비율이 증가함에 따라 공정의 안정성이 확보되고, NH₄⁺ 및 총질소(TN) 제거효율이 증가하는 경향이 나타났다. 본 연구의 결과는 수처리공정에서의 안정적인 ANAMMOX 공정 적용을 유도하고, ANAMMOX 공정의 성능개선을 도모하는 연구의 기초로 활용될 수 있다.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.277-277
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• 2015

본 연구는 퍼클로레이트의 생물학적 환원 과정에 있어서 나이트레이트의 존재가 미생물에게 어떤 영향을 미치는지를 실험을 통해서 알아보고 적절한 모델링 접근을 통하여 나이트레이트의 퍼클로레이트 환원에 대한 저해의 정량적 분석을 위한 요소들을 도출하기 위해 수행되었다. 100mL 합성폐수를 포함하는 플라스크를 이용한 실험이 수행되었고, 유일 탄소원으로 아세트산나트륨이 사용되었고, 전자수용체로는 퍼클로레이트와 나이트레이트가 사용되었다. 먼저 퍼클로레이트와 나이트레이트 각각을 단일전자수용체로서 넣은 실험을 진행하였다. 퍼클로레이트의 동역학계수 qmax, Ks, Y, b값은 각각 0.9(mgClO4-/mgMLSSday), 42.28(mgClO4-/L), 0.382(mgClO4-/mgMLSS), 0.05(day-1)로 계산되었다. 그리고 나이트레이트의 동역학 계수 qmax, Ks, Y, b값은 각각 13.81(mgNO3-/mgMLSSday), 239.78(mgNO3-/L), 0.275(mgNO3-/mgMLSS), 0.05(day-1)로 계산되었다. 나이트레이트와 퍼클로레이트를 동시에 넣었을 경우에는 나이트레이트의 동역학 계수는 qmax, Ks, Y, b 값은 각각 13.72(mgClO4-/mgMLSSday), 235.64(mgClO4-/L), 0.263(mgClO4-/mgMLSS), 0.05(day-1)로 큰차이 없었으나, 퍼클로레이트의 경우에는 qmax, Ks, Y, b값은 각각 0.6(mgClO4-/ mgMLSSday), 42.24(mgClO4-/L), 0.393(mgClO4-/mgMLSS), 0.05(day-1)로 qmax값은 감소하였고, Y값은 증가하는 모습을 보임으로써, 나이트레이트의 존재가 퍼클로레이트의 환원을 저해시키는 것을 확인할 수 있었다.

• Polymer(Korea)
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• v.24 no.4
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• pp.556-563
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• 2000

In general, the development of thermoplastic composites has been confronted with difficult problems such as the weak bonding strength between fibers and matrix. However, now, such problems are being surmounted by the development of resins, the improvement of processes, and introduction of interphase. Especially, the introduction of interphase between fiber and matrix can help a dissipation of the impact energy and provide a good adhesion between fibers and matrix. In this study, polymeric interphase was introduced by electrodeposition, modified polypropylene was added to improve the weak bonding strength between interphase and polypropylene matrix. By evaluation of interlaminar shear strength and impact strength of the composites, it was found that composites with introduced composites showed higher mechanical properties than those of composites without interphase. Reactive polymers which have either anhydride or free acid functional group were used as interphase materials, and these polymers also behave as charge carrier in aqueous solution during the electrodeposition process. Weight gain on the carbon fibers was evaluated by changing process parameters such as concentration of solution, current density, and electrodeposition time.

• Korean Journal of Environmental Agriculture
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• v.31 no.2
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• pp.104-112
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• 2012

BACKGROUND: Agricultural inputs (fertilizer and organic inputs) and water conditions can influence $CH_4$ and $CO_2$ emission from agricultural soils. This study was conducted to investigate the effects of agricultural inputs (fertilizer and organic inputs) under changing water regime on $CH_4$ and $CO_2$ emission from a soil in a laboratory incubation experiment. METHODS AND RESULTS: Four treatments were laid out: control without input and three type of agricultural inputs ($(NH_4)_2SO_4$, AS; pig manure compost, PMC; hairy vetch, HV). Fertilizer and organic inputs were mixed with 25 g of soil at 2.75 mg N/25 g soil (equivalent to 110 kg N/ha) in a bottle with septum, and incubated for 60 days. During the first 30-days incubation, the soil was waterlogged (1 cm of water depth) by adding distilled water weekly, and on 30 days of incubation, excess water was discarded then incubated up to 60 days without addition of water. Based on the redox potential, water regime could be classified into wetting (1 to 30 days), transition (31 to 40 days), and drying periods (41 to 60 days). Across the entire period, $CH_4$ and $CO_2$ flux ranged from 0 to 13.8 mg $CH_4$/m/day and from 0.4~1.9 g $CO_2$/m/day, and both were relatively higher in the early wetting period and the boundary between transition and drying periods. During the entire period, % loss of C relative to the initial was highest in HV (16.4%) followed by AS (8.1%), PMC (7.5%), and control (5.4%), indicating readily decomposability of HV. Accordingly, both $CH_4$ and $CO_2$ fluxes were greatest in HV treatment. Meanwhile, the lower $CH_4$ flux in AS and PMC treatments than the control was ascribed to reduction in $CH_4$ generation due to the presence of oxidized compounds such as ${SO_4}^{2-}$, $Fe^{3+}$, $Mn^{4+}$, and ${NO_3}^-$ that compete with precursors of $CH_4$ for electrons. CONCLUSION: Green manure such as HV can replace synthetic fertilizer in terms of N input, however, it may increase $CH_4$ emission from soils. Therefore, co-application of green manure and livestock manure compost needs to be considered in order to achieve satisfactory N supply and to mitigate $CH_4$ and $CO_2$ emission.

• Journal of Soil and Groundwater Environment
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• v.12 no.2
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• pp.1-8
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• 2007

A series of batch and column experiments were conducted for the development of biobarrier technology which can be applied to containment and reduction of contaminants in soil and ground waters. The growth kinetic constants of Pseudomonas fluorescens on glucose or molasses were determined using batch experiments. The maximum specific growth rate (Vmax) of P. fluorescens at $23^{\circ}C$ on glucose or molasses were $0.246\;hr^{-1}$ and $0.073\;hr^{-1}$, respectively. However, molasses was selected as carbon source due largely to the absence of lag phase of P. fluorescens growth on molasses and economic reason. In constant head column experiments, the hydraulic conductivity of the column soil reduced by $6.8{\times}10^{-3}$ times from $4.1{\times}10^{-2}cm/sec$ to $2.8{\times}10^{-4}cm/sec$ after the inoculation of P. fluorescens and administration of carbon source and nutrients. The biomass concentration was observed highest in the column inlet. Measurements of carbon source and electron accepter (dissolved oxygen) concentration showed that the growth of P. fluorescence, which is the main reason for hydraulic conductivity reduction, was limited not by the concentration of carbon source but by the concentration of electron acceptor.

• Korean Journal of Microbiology
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• v.48 no.3
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• pp.180-186
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• 2012

Pseudomonas aeruginosa, a Gram-negative bacterium, is an ubiquitous and opportunistic human pathogen, which expresses many virulence factors through quorum sensing (QS) regulation. QscR, one of the QS signal receptors of P. aeruginosa, has unique features that make it possible to distinguish QscR from other QS receptors. In the present study, we focused on amino acid residues responsible for such a broad signal specificity of QscR. Thus we constructed mutant QscRs: $QscR_{T72I}$, $QscR_{R132M}$, and $QscR_{T140I}$ by substituting $72^{nd}$ threonine, $132^{nd}$ arginine, and $140^{th}$ threonine residues with isoleucine, methionine, and isoleucine, respectively by site-directed mutagenesis. When we examined the activity of these mutant QscRs, $QscR_{R132M}$ failed to respond to N-3-oxododecanoyl homoserine lactone (3OC12-HSL), but $QscR_{T72I}$ and $QscR_{T140I}$ remained the ability to respond to 3OC12-HSL despite much reduction of the sensitivity. When we treated a variety of acyl-HSLs with different structure, $QscR_{T72I}$ and $QscR_{T140I}$ showed better responsiveness to N-decanoyl HSL (C10-HSL) or N-dodecanoyl HSL (C12-HSL) that has no oxo-moiety at $3^{rd}$ carbon of acyl group than to 3OC12-HSL, and $QscR_{R132M}$ showed no responsiveness to any acyl-HSLs tested here. In addition, $QscR_{T72I}$ and $QscR_{T140I}$ were inhibited by 5f, a QscR inhibitor as similarly as wild type QscR was. These results suggest that while the $130^{th}$ arginine is crucial in both activity and acyl-HSL binding of QscR, the $72^{nd}$ and $140^{th}$ threonines are important in the activity, but they are little responsible for the discrimination of acyl-HSLs or competitive inhibitor.

• Applied Chemistry for Engineering
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• v.27 no.1
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• pp.1-9
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• 2016

The co-culture system of microalgae and bacteria enables simultaneous removal of BOD and nutrients in a single reactor if the pair of microorganisms is symbiotic. In this case, nutrients are converted to biomass constituents of microalgae. This review highlights the importance and recent researches using symbiotic co-culture system of microalgae and bacteria in wastewater treatment, focusing on the removal of nitrogen and phosphorus. During wastewater treatment, the microalgae produces molecular oxygen through photosynthesis, which can be used as an electron acceptor by aerobic bacteria to degrade organic pollutants. The released $CO_2$ during the bacterial mineralization can then be consumed by microalgae as a carbon source in photosynthesis. Microalgae and bacteria in the co-culture system could cooperate or compete each other for resources. In the context of wastewater treatment, positive relationships are prerequisite to accomplish the sustainable removal of nutrients. Therefore, the selection of compatible species is very important if the co-culture has to be utilized in wastewater treatment.

• Reproductive and Developmental Biology
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• v.29 no.1
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• pp.43-48
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• 2005

To search of a new porcine pheromonal odorants for biostimulation control system technologies to offer a potentially useful and practical way to improve reproductive efficiency in livestock species, the holographic quantitative structure activity relationship (HQSAR) model between odorants, 2-phenoxytetrahydrofurane (A), 2-cyclohexyl-oxytetrahydrofurane (B), derivatives and binding affinity constants (p[Od.]/sub 50/) for porcine odorant-binding protein (pOBP) as receptor of pig pheromones were derivated and disscused. The binding affinity constants of cyclohexyl substituents (A) for pOBP were higher (A>B) than that of phenyl substituents (B). It was revealed that the optimum HQSAR model XI using PLS analyses had a fragment length (5∼8) with chirality at 5 components and hologram length 97 bin, which had a cross-validated q²(predictablities) of 0.916, and a conventional correlation coefficient r² (fitness) of 0.988, respectively. From the atomic contribution, the C3 and C5 atom in 2-oxyfuryl group contributed to binding affinity constants, whereas the central carbon atom in tert-butyl group on the cyclohexyl ring and the C4 atom of furyl group parts showed no contribution.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.2
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• pp.303-311
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• 2000

This study was conducted to find an optimal TNT transformation condition with the addition of different carbon and energy sources in a batch reactor. When TNT and nitrate were present in the medium, the cell growth and TNT transformation was slower because nitrate and TNT was competitively served as electron acceptor. Transformation of TNT was faster when TNT in the medium was nitrogen source and acetate as a carbon source. Cell growth and nitrate transformation was slower when yeast extract was not present in the medium. The proposed intermediates of TNT biotransformation from the earlier studies was not detected in this experiment but the intermediates are tentatively proposed as nitro and amino-free compounds. These results should be helpful for the operation of the munition waste treatment in the future.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2023.04a
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• pp.4-4
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• 2023

다국적 제약회사에서 생산되는 제약화합물은 인간의 질병치료 뿐만 아니라 가축의 생산성을 향상시키는 물질으로도 활발하게 생산되는데 육우의 성장을 촉진하는 기능성 화합물들도 많이 있다. 북미에서 생산되는 소고기의 약 80%가 1번 이상의 성장촉진기술들이 활용되고 있다고 보고된다. 고기소로 생산되는 비육우에 적용되는 방법은 크게 피하 이식에 의해 혈류를 타고 성장을 촉진하는 17β-Estradiol과 합성 남성호르몬제인 Trenbolone acetate가 주로 활용되고, 비육후기 사료에 섞어서 급여하는 사료첨가제 형태인 β2-adrenergic agonist 같은 형태로 적용하게 된다. 근육을 성장하는 기술의 작용기전은 많은 선행연구에 의해 밝혀져 있는 반면 천연 알칼로이드 성분들의 기전은 밝혀진 것이 많지 않다. 한방제재들에서 많이 발견되는 알칼로이드 성분들은 생리활성 기능들을 가진 것으로 알려져 있지만, 생산, 수거, 가공, 추출 등의 공정에서 많은 비용이 발생하므로 비육우의 사료화 가능성은 아주 희박하다. 따라서 비용을 최소화 할 수 있는 후보재료를 검색중에 감자부산물을 확보하였고 기능성 물질의 추출과 사료첨가제 화 하여 비육우에 급여시험을 실시하였다. α-solanine과 α-chaconine은 감자의 잎, 과일 및 괴경에서 발견되는 글리코알칼로이드 화합물로, 쥐, 토끼, 닭과 같은 다양한 동물 모델에서 중독성을 가진 물질로 보고 되고 있다. 최근 연구에서는 비육우의 성능을 유도하는 데 사용되는 것으로 나타났다. 한우 송아지 3마리의 사태(Semimembranosus)와 등심(Longissimus Dorci)근육에서 추출된 근육위성 세포(BSC)에 다양한 수준의 α-solanine(control, 0.001, 0.01, 0.1, 1, 10μM)으로 처리해본 결과 근육관련 지표인 MHC2X과 β2-AR의 발현이 높게 나타난 것을 확인했다. 사료급여실험에서는 대조군에 비해 급여군의 등심단면적과 도체중이 향상되는 것을 확인하였다. 결과적으로 감자유래 농산부산물은 한우 비육우의 근육의 성장을 증가시키고, 그 작용기전은 β2-수용체에 작용하여 단백질 합성을 촉진시켜 근육을 축적시키는 것으로 확인하였다. 농산부산물을 이용한 기능성 사료개발은 최근 이슈가 되고 있는 축산분야 탄소저감을 개선할 수 있는 기술로 축산의 업사이클링 기술로 활용 가능하다.