• Korean Chemical Engineering Research
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• 제56권2호
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• pp.156-161
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• 2018

염소법과 졸-겔법으로 $TiO_2$ 광촉매 분말을 제조하였다. 제조방법 및 조건에 따라 촉매의 결정상 형태(아나타제와 루타일)와 비표면적이 변화하는 것을 알 수 있었다. TTIP-sol로 제조한 광촉매가 염소법이나 TBOT-sol로 제조한 광촉매에 비해 methylene blue (MB) 분해 특성이 더 높았으며, 수용액상의 90% 이상의 MB를 제거할 수 있었다. 실험 결과를 통해 $TiO_2$ 광촉매는 단일 아나타제상와 큰 비표면적을 가지면 유기물 분해 특성을 향상될 수 있는 것을 확인하였다.

• 유기물자원화
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• 제29권4호
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• pp.55-65
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• 2021

본 연구는 독일 유기물분해율 표준시험법인 VDI4630 시험을 통해 메탄 생성 및 유기물의 분해율을 조사하였으며 시험을 위해 농업 분야의 11개의 폐기물 바이오매스를 공시재료로 선택하여 시험하였다. 본 연구의 목적은 초기에 빠르게 분해되는 생분해성 유기물과 이후 천천히 지속적으로 분해되는 유기물의 비율을 계산하기 위해 Double first-order kinetics 모델을 이용하여 유기물의 분포를 추정하고자 하였다. 그 결과로 본 연구에 적용된 모든 바이오매스는 초기 단계에서 빠른 분해를 보이다가 이후 분해 속도가 일정 시간 느려지기 시작하여 초기 분해 속도보다 10배 이상 느려지는 결과를 보였다. 이러한 분해율 변화 경향은 바이오매스 분해의 전형적인 형태이며 쉽게 분해되는 인자(k₁)는 채소 작물에서 0.097~0.152 day^-1 범위였고, 분해에 저항성을 가지는 인자(k₂)는 0.002~0.024 day^-1 사이에 위치하였다. 유기물 분해율이 높을수록 k₁ 상수 값이 더 크게 나타났으나 (0.152, 0.144day^-1) 오이와 파프리카 열매와 같이 표면에 왁스층이 존재하는 부산물은 k₁ 값이 오히려 줄기보다 낮았고 (0.002, 0.005day^-1), 무와 귤껍질도 k₁ 각각 0.097과 0.094 day^-1로 낮은 분해율과 k₁ 값을 보여 유기물의 분해율은 이분해성 유기물 분해 상수인 k₁ 값에 크게 영향을 미치는 것으로 분석되었다.

• 환경생물
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• 제23권2호
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• pp.135-140
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• 2005

In order to construct an artificial cultivation of Nostoc flagelliforme on solid medium, we attempted to assess the viability of approaches, which utilized either BG-11 agar or sand medium using both sterile and non-sterile algal segments. In the trial in which the BG -11 agar medium was inoculated with the non-sterile algal segments, the algae exhibited the rapid growth in the initial 4 days of cultivation. However, after 4 days of cultivation, the growth rate of the algae slowed, and the algal growth was completely stopped by 7 days of cultivation. When the BG -11 medium was inoculated with the sterile algal segments, the algae exhibited the rapid growth for a longer period of 8 days, reaching a length of 24.9 mm. The growth rate during this period was measured to be $24.5\%$. After the 8 days of cultivation, the algal growth rate began to slow and had almost stopped by the 13 days of cultivation. On the other hand, when the sterile algal segments were inoculated onto a sand plate, the algal segments decomposed, reaching total decomposition after 11 days of cultivation. By way of contrast, the desiccation treatment samples continued to grow for 14 days of cultivation. After 14 days of cultivation, the algae achieved a length of 26.1 mm, with a growth rate of $30.6\%$. Our results indicate that periodic desiccation may constitute an effective strategy for the prevention of algal decomposition.

• 한국토양비료학회지
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• 제48권5호
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• pp.542-548
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• 2015

This study investigated methane productions and a degradation rate of organic matters by German standard method, VDI4630 test. In this study, 4 livestock byproducts from livestock farm were selected for the investigation. The objective of this study was to estimate a distribution of organic matters by using the double first-order kinetics model in order to calculate the rate of biodegradable organic matters which degrade rapidly in the initial stage and the persistently biodegradable organic matters which degrade slowly later. As a result, all the byproducts applied in this study showed rapid decomposition in the initial stage. Then the decomposition rate began to slow down for a certain period and the rate became 5 times slower than the initial decomposition rate. This trend of decomposition rate changes is typical conditions of organic matter decompositions. The easily degradable factors ($k_1$) ranged between $0.145{\sim}0.257day^{-1}$ and persistent degradable factors ($k_2$) were $0.027{\sim}0.080day^{-1}$. Among these results, greater organic matter decomposition rates from VDI4630 had greater $k_1$ values (0.257, $0.211day^{-1}$) and smaller $k_2$ values (0.027, $0.030day^{-1}$) for dairy wastewater and forage byproduct, respectively.

• 한국지반공학회논문집
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• 제20권8호
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• pp.29-39
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• 2004

폐기물 매립지의 침하량을 예측하는 것은 우리나라와 같은 좁은 국토를 효율적으로 관리하기 위하여 매우 중요하다. 매립장내 유기물이 장기간에 걸쳐 생화학적으로 분해되기 때문에 압밀이론으로 해석하기 곤란하다. 본 연구에서는 실내모델실험을 통하여 매립가스의 발생특성을 분석하였다. 두개의 시험매립조를 만들었는데 하나는 침출수를 재순환한 것과 다른 하나는 재순환하지 않은 것이다. 시간의 변화에 따른 가스발생량과 매립조의 침하량과의 관계를 분석하였다. 수학적 침하량예측모델을 제안하여 장기침하량을 예측하여 실험계측치와 비교하고 수정계수를 사용하도록 제안하였다. 침출수 재순환이 침하를 촉진하는 효과가 있는 것으로 나타났는데 가스모델의 수정계수가 침출수순환을 하지 않은 경우는 1.4, 재순환한 경우는 1.7으로서 약 22%의 촉진효과가 있다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 추계학술대회 논문집
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• pp.514-517
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• 2009

Anaerobic biodegradability(AB), which can be determined with the ultimate methane yield by the decomposition of organic materials, is one of the important parameters for the design and the operation of anaerobic digestion plant. In this study, Biochemical Methane Potential(BMP) test has been carried out to evaluate the methane yield of agro-industrial biomasses such as cattle manure, Italian ryegrass(IRG), Oats, Rye and Barley as the forage crops, Rush, the sludges produced from milling and slaughterhouse wastewater treatment plant(SMWTP, SSWTP). In the condition of thermophilic anaerobic digestion, the ultimate methane yield and anaerobic biodegradability of forage crops ranged from 0.367 to $0.452LCH_4$/gVS of methane yield with AB having the range of about 77.0 to 87.3%. On the other hand, that of other substrate showed low figures compared with the forage crops because of low VS content and C/N ratio. Therefore, the forage crops could be used as a good substrate to produce much more the methane in anaerobic digestion.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2008년도 추계학술대회 논문집
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• pp.79-82
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• 2008

Anaerobic biodegradability(AB), which can be determined with the ultimate methane yield by the decomposition of organic materials, is one of the important parameters for the design and the operation of anaerobic digestion plant. In this study, Biochemical Methane Potential(BMP) test has been carried out to evaluate the methane yield of animal manures, such as pig and cattle slurries, and different forage crops cultivated at the reclaimed tideland, such as maize, sorghum, barley, rye, Italian ryegrass(IRG), rape, rush and sludge produced from slaughterhouse wastewater treatment plant(SWTP). In the ultimate methane yield of animal manure, that of pig slurry(no used a EM) was 407 $mlCH_4/gVS_{fed}$ higher than 242 $mlCH_4/gVS_{fed}$ of cattle slurry. The ultimate methane yield of spike-crop rye was 442.36 $mlCH_4/gVS_{fed}$ the highest among different forage crops, the other showed the value above a methane yield of 300 $mlCH_4/gVS_{fed}$. The forage crop could be used as a good substrate to improve the methane production in anaerobic co-digestion together with animal manure.

• Environmental Engineering Research
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• 제24권2호
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• pp.202-210
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• 2019

In order to maximize the utilization of sewage sludge, a waste from wastewater treatment facility, the residual sewage sludge generated after lipid and carbohydrate extraction for biodiesel and bioethanol production was used to produce bio-oil by pyrolysis. Thermogravimetric analysis showed that sludge pyrolysis mainly occurred between 200 and $550^{\circ}C$ (with peaks formed around 337.0 and $379.3^{\circ}C$) with the decomposition of the main components (carbohydrate, lipid, and protein). Bio-oil was produced using a micro-tubing reactor, and its yield (wt%, g-bio-oil/g-residual sewage sludge) increased with an increase in the reaction temperature and time. The maximum bio-oil yield of 33.3% was obtained after pyrolysis at $390^{\circ}C$ for 5 min, where the largest amount of energy was introduced into the reactor to break the bonds of organic compounds in the sludge. The main components of bio-oil were found to be trans-2-pentenoic acid and 2-methyl-2-pentenoic acid with the highest selectivity of 28.4% and 12.3%, respectively. The kinetic rate constants indicated that the predominant reaction pathway was sewage sludge to bio-oil ($0.1054min^{-1}$), and subsequently to gas ($0.0541min^{-1}$), rather than the direct conversion of sewage sludge to gas ($0.0318min^{-1}$).

• Membrane and Water Treatment
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• 제11권3호
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• pp.195-200
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• 2020

In this study, a biocatalyst composite was prepared by immobilizing oxidoreductases onto Cu-activated zeolite to facilitate biochemical decomposition of 4-chlorophenol (4-CP). 4-CP monooxygenase (CphC-I) was cloned from a 4-CP degrading bacterium, Pseudarthrobacter chlorophenolicus A6, and then overexpressed and purified. Type X zeolite was synthesized from non-magnetic coal fly ash using acetic acid treatment, and its surfaces were coated with copper ions via impregnation (Cu-zeolite). Then, the recombinant oxidative and reductive enzymes were immobilized onto Cu-zeolite. The enzymes were effectively immobilized onto the Cu-zeolite (79% of immobilization yield). The retained catalytic activity of CphC-I after immobilization was 0.3423 U/g-Cu-zeolite, which was 63.3% of the value of free enzymes. The results of this study suggest that copper can be used as an effective enzyme immobilization binder because it provides favorable metalhistidine binding between the enzyme and Cu-zeolite.

• 미생물학회지
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• 제39권2호
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• pp.67-75
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• 2003

비교유전체학의 주요 주제 중 유전자서열을 분류하고 단백질기능을 예측하는 연구가 있으며, 이를 위해 단백질 구조, 공통서열 및 바인딩 위치 예측등의 방법과 함께, 전유전체 서열에서 구해지는 유사도 그래프를 분석해 상동유전자를 검색하는 계산학적인 접근방법이 있다. 유사도그래프를 사용한 방법은 서열에 대한 기존 지식에 의존하지 않는 장점이 있지만 유사도 하한값과 같은 주관적인 임계값이 필요한 단점이 있다. 본 논문에서는 반복적으로 그래프를 분해하는 이전의 방법을 일반화시켜, 유사도 그래프에 기반한 유전자 서열군집분석 방법론과 객관적이고 안정적인 파라미터 임계값 계산 방법을 제안한다. 제시된 방법으로 알려진 미생물 유전체 서 열을 분석하여 이전의 방법인 BAG 알고리즘 결과와 비교했다.