• Journal of the Korea Organic Resources Recycling Association
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• v.8 no.4
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• pp.78-85
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• 2000

Leachate from acidogenic fermentation of food waste was effectively treated by the UASB reactor at $37^{\circ}C$. The efficiency of COD removal was consistently over 96% up to the loading rates of $15.8g\;COD/{\ell}{\cdot}d$. The methane production rate increased to $5.5{\ell}/{\ell}{\cdot}d$. Of all the COD removed, 92% was converted to methane and the rest presumably to biomass. At loading rates over $18.7g\;COD/{\ell}{\cdot}d$, the efficiency of COD removal decreased due to the sludge flotation and washout in the reactor, which resulted from short HRT of less than 10.6 hr. The SMA(specific methanogenic activity) analysis showed that the VFA-degrading activity of granule was the highest for butyrate, and the lowest for propionate. This result was consistent with the observation that the residual propionate concentration was the highest among the VFAs in the effluent. Typical granules were found to be mainly composed of microcolonies of Methanosaeta. Though the original seed sludge contained 64.3% of particles smaller than 1.4mm, the sludge particles had been growing during the fermentation, and at the final step of this study, 75.1% of the particles were found to be larger than 1.4 mm in the UASB reactor.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.2024-2028
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• 2007

우리나라의 물관련 이슈는 수자원뿐만 아니라 사회, 경제 환경 등의 범위까지 확대되어 복합적이며, 기존 방법론과 기술만으로는 해결에 어려움이 있다. 따라서 새로운 기술적/방법론적 도구 개발의 필요성에 따라 통합수자원관리가 하나의 방법으로 받아들여지고 있다. 통합수자원관리는 지속가능한 수자원관리를 목표로하며, 물과 이와 관련 다양한 요소를 고려하는 통합적인 방법론이다. 그러므로 의사결정에 있어 전체론적인 접근이 필요하며, 세부적인 요소와 요소간의 연관관계를 파악하는 것이 중요하다. 이를 위하여 본 연구에서는 통합수자원관리의 기반 도구 중의 하나인 통합수자원관리 모델링 환경인 WaterRing 시범시스템을 개발하였다. WaterRing은 모델연계에 있어 필수적인 표준성, 사용편의성 및 모델공유를 제공하며, 모델코드 자체보다 모델의 개발에 많은 노력을 기울일 수 있도록 설계되었다. 따라서 수자원분야 및 다양한 분야의 모델을 연계할 수 있다. 모델의 연계를 위하여 기본모델단위를 설정하고 각각의 기본모델단위의 결합을 통하여 보다 큰 시스템으로 구성할 수 있도록 하였다. 기본모델단위는 입력/상태/출력의 세 가지 기본요소와 내부수행 루틴으로 구성되어 있다. 기본모델단위 사이의 결합을 정의하기 위하여 BPM(Business Process Management)(Arkin, 2002)와 STELLA의 모델 결합방식을 활용하였다. 기본모델단위는 독립적인 수행단위로 표준적인 입력과 출력을 수행한다. 따라서 입력과 출력의 속성이 같은 기본모델단위는 결합할 수 있다. 본 연구에서 시범적으로 개발된 수자원통합모델링환경 WaterRing은 통합수자원관리의 실현에 있어 평가, 계획에 이용될 수 있다. 그러므로 향후 시스템의 개발이 완료되면 우리나라의 통합수자원관리의 실현을 위한 기반도구로서 많은 역할이 기대된다. 홍수기에 측정된 성과를 바탕으로 고수위대의 수위-유량관계 곡선식을 개발하여야 할 것으로 판단된다. 본 연구를 통해 일부 확인된 바와 같이, 일반적인 자연하천이 아닌 감조하천의 경우는, 각각의 수위대별 유량 값의 변화가 발생하는 바 기간별 혹은 간조와 만조부를 포함하여 유량측정을 하여야 할 것으로 판단된다. 청폐화담탕(淸肺化痰湯)은 LPS로 유도된 macrophage에서 NO와 염증Cytokine 생성량을 억제하였고 murine macrophage에서 NF-${\kappa}$B 활성을 억제함으로써 iNOS와 염증Cytokine 유전자 발현을 하향조절 하였다. 이러한 청폐화담탕(淸肺化痰湯)의 항염작용으로 천식, 기관지염, 폐렴, 결핵, 산후감모 등의 호흡기 질환에 응용할 수 있으리라 사료된다.im}$5개월), 9.44${\pm}$1.05 6${\sim}$ll개월)으로 개월에 관계없이 전반적으로 유사한 비율을 나타내었다. 분획물(첨가농도 15.6 ${\mu}$g/ml)은 60%의 저해효과를 나타내면서 농도 의존적으로 그 저해효과가 컸으며 250 ${\mu}$g/ml 농도에서는 80%의 저해효과를 관찰 할 수가 있었다. 에틸아세테이트분회물의 경우 디글로로메탄 분회물에 비해 다소 낮은 저해효과를 나타내었지만 250 ${\mu}$g/ml 농도에서 약 60%의 세포독성 효과를 나타내었다. 디클로로메탄 분획물과 에틸아세테이트 분획물에 의한 면역 활성 증진 효과를 검토한 결과, 디글로로메탄 분획물은 첨가농도 1 ${\mu}$g/ml에서 94%로 Yac-1표적세포를 사멸시켰으며 에틸아세테이트 분획물도 동일 농도에서 96%의 억제효과를 나타내었다. CTLL세포를 이용

• Applied Chemistry for Engineering
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• v.5 no.2
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• pp.373-377
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• 1994

A mechanism for the synthesis of benzophenone from oxidation of diphenylmethane under Aliquit 336 phase transfer catalyst is investigated in this study. The production rate of benzophenone increased with the increasing amount of Allquat 336 and potassium tert-butoxide. At low concentrations of diphenylmethane and oxygen, the reaction order was first with the concentrations of diphenylmethane and oxygen respectively, but it approached to zero order at high concentrations. Tert-butyl alcohol, by-product of the reaction, inhibited the formation of benzophenone. Experimental results fit fairly well to the following initial reaction rate equation derived from reaction mechanism. $$({\gamma}_{BP})_0={\frac{k_1k_3k_5[QCI]_0[DPM]_0[PTB]_0[O_2]_0}{k_2k_4[TBA]_0+k_2k_5[O_2]_0+k_3k_5[O_2]_0[DPM]_0}}$$

• Journal of Korean Society of Environmental Engineers
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• v.31 no.2
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• pp.90-95
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• 2009

Sludge pre-treatment utilizing cavitation is one of the commercialized methods at present. Cavitation can be generated by two different methods, sonotrode and hydrodynamic principle, and there has been no direct comparison between the two methods. In this study, solubilization efficiency, changes in sludge size distribution, and the methane production potential after pre-treatment by the two methods were compared. The maximum solubilization efficiency per unit energy input with the two methods was similar, and was 302 mg ${\Delta}SCOD/g$ TS at the energy input of 0.18 kWh/L. Break-up of sludge flocs were dominant during the early period of pre-treatment, while cell disintegration continued through the pre-treatment with the increase in the number of particles with less than 1 ${\mu}m$. BMP test results indicated that the methane potential increased up to 24.3% without differences between the two pre-treatments, and the increase in methane potential did not proportional to energy input. Although the energy efficiency of the two methods was quite similar, hydrodynamic methods might be a better choice for field application considering the operation and maintenance cost, and its potential improvement in energy efficiency.

• KSBB Journal
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• v.22 no.2
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• pp.97-101
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• 2007

This study was performed to examine the availability of anaerobic digestion of the remainders caused by bacterial cellulose production process using food wastes. They maybe to be considered as others second pollution sources. Thus, this study was targeted to minimize content of organic material and to obtain more energy in those remnants using two-phase UASB reactor. The working volume of first hydrolysis fermentor was 35 L (total 55 L) and the second methane fermentor was 40 L (total 50 L). The organic loading rate of hydrolysis fermentor was 3 g-VS/L${\cdot}$day and 25,000 ppm of $COD_{cr}$ for methane fermentor. The hydraulic retention time was 18 days for hydrolysis reactor and 33 days for methane reactor. The hydrolysis reactor and methane reactor were performed at 35, 40$^{\circ}C$ respectively. For the efficient stable performance, the composition of organic wastes at each stage was as follow; Food waste with bacterial culture remnants (1 : 1), bacterial cellulose remnants, bacterial cellulose culture remnants with food wastes saccharified solids (1 : 1). When the anaerobic digestion was performed stably at each stage, the COD removal efficiency was 88, 90, 91 % respectively. At this time, methane production rate was 0.26, 0.34, $0.32m^3\;CH_4/kg-COD_{remove}$. As well as the values of anaerobic digestion at third stage were more higher than values of anaerobic digestion using food wastes. It is clearly to say that the food wastes zero-emission system constructed in our lab is more efficient way to treat and reclaim food wastes.

• Applied Chemistry for Engineering
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• v.34 no.4
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• pp.404-411
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• 2023

For the direct reforming of biogas, a three-phase gliding arc plasma reformer was designed to expand the plasma discharge region, and the operation conditions of the plasma reformer, such as the S/C ratio, the gas flow rate, and the plasma input power, were optimized. The H₂ production efficiency is increased at a lower specific plasma input energy density, but byproducts such as C_XH_Y and carbon soot are generated along with the increase in H₂ production efficiency. The formation of byproducts is decreased at higher specific plasma input energy densities and S/C ratios. The optimized operation conditions are 5.5 ~ 6.0 kJ/L for the specific plasma input energy density and 3 for the S/C ratio, considering the conversion efficiency, H₂ production, and byproduct formation. It is expected that the H₂ production efficiency will improve with the decrease in fuel consumption in biogas burners because the heat generated from plasma discharge heats up the feed gas to over 500 ℃.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.264-267
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• 2005

수소의 소규모 분산 생산 기술은 본격적 인 수소 인프라가 도입되기 전에 연료전지 자동차의 수소 충 전용이나 분산 발전형 연료전지의 수소 공급을 위해 필요하다. 생산 용량은 수소 기준으로 $10\~100 Nm^3/hr$ 정도로 현재로선 천연가스의 수증기 개질법이 가장 경제적인 공정으로 알려져 있다. 소규모 생산에 따른 열효율 저하를 줄이 기 위해 단위 공정들이 통합된 컴팩트 개질 시스템의 개발이 필요하다. 핵심 기술인 컴팩트 리포머의 국산화 기술 확보를 위하여 $20 Nm^3/hr$용량의 동심관형 리포머를 설계, 제작하였다. 내부구조는 제작의 단순화를 고려하여 중첩된 동심관이 배열되었고 압력 손실과 열웅력 발생을 억제하도록 유로를 배치하였다. 수증기개질 반응에 필요한 반응열은 리포머 본체에 부착된 버너를 이용하여 공급하였다. 성능 측정을 위한 부속 기기로 상온 흡착식 탈황기, 폐열 회수형 수증기 발생기, 반응물 예열을 위한 열교환기, 생성 가스 응축기를 설계 제작하여 전체 리포밍 시스템을 구성하였다. 반응 온도 $680\~720^{\circ}C$, 탄소 대 수중기 비(S/C ratio) $2.7\~3.2$ 조건에서 수증기 개질 반응을 수행하였다. 해당 반응 조건에서 메탄 전환율 $89\%$ 이상, 저위 발열량 기준 개질 열효율 $70\%$ 이상을 달성하였고 개질 생성가스 내 수소의 최대 유량은 $23.4Nm^3/h$였다. 개발된 리포밍 시스템은 고순도 수소 생산이 필요한 경우, 수소 수율 향상을 위한 고온 수성 가스 전화 반응기를 통합 가능하도록 열교환기 구성을 조정할 수 있으며 용융 탄산염 연료전지와 같이 고온형 연료전지의 경우 $550^{\circ}C$ 이상으로 개질 생성 가스를 공급하도록 구성할 수도 있다. 향후 리포머 본체의 개질 효율 향상 및 장치 소형화, 부속 기기의 최적화를 통한 전체 리포밍 시스템 개선, 스케일 업 설계를 위한 엔지니어링 설계 패키지 구성을 계획하고 있다.

• Korean Journal of Agricultural and Forest Meteorology
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• v.9 no.3
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• pp.161-169
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• 2007

Global climate changes including elevated $CO_2$, drought, and global warming may influence greenhouse gas emissions in wetlands. A variety of microbial communities including denitrifiers and methanogens play a key role in determining such processes. In this paper we summarize current knowledge on the effects of climate changes on $CO_2,\;CH_4$, and $N_2O$ production and microbial communities mediating those processes in wetlands. Elevated atmospheric $CO_2$ and warming generally increase gas emissions, but effects of droughts differ with gas type and drying level. The responses of microbial community to climate changes in terms of composition, diversity and abundance are still in question due to lack of studies in wetlands. Based on the present review, it is suggested that future studies on microbial processes should consider microbial community and relationships between microbial function and structure with diverse environmental factors including climate changes. Such knowledge would be crucial to better understand and predict accurately any shifts in ecological functions of wetlands.

• Applied Chemistry for Engineering
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• v.19 no.2
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• pp.209-213
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• 2008

The fixed bed gasification reactor with 1 m hight and 10.2 cm diameter was utilized for the hydrogen production from biomass wastes. Lauan sawdust was used for non-catalytic and catalytic gasification reaction as a sample in the fixed bed reactor. The fixed bed temperature and catalyst are the major variables affecting the process operation. Thus, the effect of fixed bed temperature and the catalysts on gas composition were studied at the temperature range from $400^{\circ}C$ to $700^{\circ}C$. The yield of hydrogen was increased at higher temperature in the fixed bed reaction. Fractions of hydrogen, carbon monoxide and methane gas in the product gas increased when sodium carbonate ($Na_2CO_3$) and potassium carbonate ($K_2CO_3$) catalysts were used. Furthermore, sodium carbonate catalyst was more effective to obtain higher hydrogen yield compared to potassium carbonate catalyst.

• Korean Journal of Materials Research
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• v.5 no.6
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• pp.732-742
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• 1995

Effects of the substrate pretreatment on uncleation density of the diamond thin films have been investigated. The film was prepared using the hot-filament CVD reactor with the mixture of methane and hydrogen. The substrate pretreatment was done in three different ways: predeposition of carbon on the substrate, soot on the substrate, and graphite on the substrate. All three cases enhanced the nucleation density of diamond. And the effect was more marked in the first and the second cases than in the third one. In the first case where the substrate was predeposited by the carbon phase, a very smooth and uniform film of diamond could be obtained. Since the bound strength between the substrate and the predeposited carbon phase is relatively weak, separation of the diamond film layer from the substrate was found to be easy.