• Journal of Korean Society of Water and Wastewater
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• v.13 no.4
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• pp.35-44
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• 1999

In this study, it was attempted to remove nitrate and carbon in a single-stage reactor using acetate as substrate. Hybrid type upflow sludge baffled filter reactor was adopted using anaerobic sludge. Sludge bed in the bottom of reactor was intended to remove carbon and nitrate by denitrification and methanogenesis. And floating media in the upper part of reactor were intended to remove remaining carbon which was not removed due to the inhibition of nitrogen oxide on methane producing bacteria. The reactor removed over 96% of COD and most of nitrate with volumetric loading rate of $4.0kgCOD/m^3{\cdot}day$, hydraulic retention time of 24hr, 4,000mgCOD/L, and $266mgNO_3-N/L$. Nitrate in anaerobic sludge was converted to nitrogen gas(denitrification) or ammonia (ammonification) according to pH of influent, COD removal efficiency was easily affected by the change of volumetric loading rates and nitrate concentration. And when influent pH was about 4.7, most nitrate changed to ammonia while when influent pH was about 6.8~7.0, most nitrate denitrified independent of $COD/NO_3-N$ ratio. Most granules were gray and a few were black. In gray-colored granule, black inner side was covered with gray substance and SEM illustrated Methanoccoci type microorganisms which were compact spherical shape. Anaerobic filter removed residual COD effectively which was left in sludge bed due to the inhibition of nitrogen oxide.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.215.1-215.1
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• 2010

가스 하이드레이트는 작은 고체 부피 내에 막대한 양의 가스를 저장할 수 있다는 특성으로 인하여, 최근 천연가스 혹은 메탄의 저장 매체로 활용하기 위한 연구가 활발히 진행중에 있다. 하지만 실제 응용을 위해서는 미세구조 분석이 수행되어 하이드레이트 형태로 저장할 수 있는 정확한 저장 용량을 파악할 필요가 있다. 본 연구에서는 여러가지의 고리형 에테르, 고리형 에스테르 및 고리형 케톤 화합물들을 테스트하여 메탄 가스와 반응하는 6가지의 새로운 sII 혹은 sH 하이드레이트 형성제를 파악하였다. 또한 새로이 발견된 형성제 모두에 대하여 하이드레이트 상평형도 측정하였다. 얻어진 상평형 데이터는 하이드레이트 안정영역과 게스트 분자 크기 간에 뚜렷한 상관관계가 있음을 입증하였다. 아울러 형성된 하이드레이트 샘플은 고체 분말 X-선 회절과 고체상 13C NMR 분석을 수행하여 하이드레이트 구조와 게스트 포집률을 조사하였다. 마지막으로, 비슷한 화학 구조식을 갖고 있음에도 2-methyltetrahydrofuran과 3-methyltetrahydrofuran, 혹은 4-methyl-1,3-dioxane과 4-methyl-1,3-dioxolane은 서로 다른 하이드레이트 결정 구조를 보여 주었는데, 이러한 차이는 하이드레이트 결정 구조를 결정짓는 게스트 분자 크기, 즉 임계 게스트 분자 크기를 파악하는 데에도 매우 유용한 정보를 제공할 수 있을 것이라 판단된다.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.102.2-102.2
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• 2010

We are to evaluate the stabilization technology of actual biogas plant facilities, which is operating currently. It describes the traits of the consistent facilities of mesophilic anaerobic digestion using Unison Biogas plant Recovery system(UBR). Also the economical efficiency is examined with the electric power sales earnings and applying the deserted heating by generating electric power, which is generated by operated combined heat and power using biogas produced by mesophilic anaerobic digestion. We have generated the 481,113kw for electric power and 1,376Gcal for thermal energy simultaneously. If these electric power and thermal energy are converted into diesel, we can achieve savings equal to 114,300L, and 152,109L in the quantity of heat. Finally, if CDM, RPS, liquid fertilizer sales business, etc. is activated, the earnings will be expected to improve dramatically and is considered to contribute a drop of the greenhouse gas.

• Applied Chemistry for Engineering
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• v.31 no.1
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• pp.1-6
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• 2020

Hydrogen production from biogas has received consistent attention due to the great potential to solve simultaneously the issues of energy demands and environmental problems. Practically, biomethane produced by purification/upgrading of biogas can be a good alternative to the natural gas which is a main reactant for a steam methane reforming process. Judging from the economic and environmental impacts, however, the steam biogas and dry reforming are considered to be more effective routes for hydrogen production because both processes do not require the carbon dioxide elimination step. Herein, we highlight recent studies of hydrogen production via reforming processes using biogas and effective applications for earlier commercialization.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.210.2-210.2
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• 2016

An inductively coupled plasma source was prepared for the deposition of a-C:H thin film. Properties of the inductively coupled plasma source are investigated by fluid simulation including Navier-Stokes equations and home-made tuned single Langmuir probe. Signal attenuation ratios of the Langmuir probe harmonic frequency were 13.56Mhz and 27.12Mhz. Dependencies of plasma parameters on process parameters were accord with simulation results. Ar/CH4 plasma simulation results shown that hydrocarbon radical densities have their lowest value at the vicinity of gas feeding line due to high flow velocity. For input power density of 0.07W/cm3, CH radical density qualitatively follows electron density distribution. On the other hand, central region of the chamber become deficient in CH3 radical due to high dissociation rate accompanied with high electron density. The result suggest that optimization of discharge power is important for controlling deposition film quality in high density plasma sources.

• Journal of Korean Society for Atmospheric Environment
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• v.20 no.5
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• pp.655-662
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• 2004

An adsorption process to recover the pure $CH_4\;and\;CO_2$ from its mixture was examined. In this study, activated carbon fibers were used as a selective adsorbent. The activated carbon fibers has 78~94% micropore volume and 10.5~20.3${\AA}$ narrow pore size, and showed high adsorption rate and the good selectivity for $CO_2$ under the ambient pressure. The ACF with high surface area showed short mass transfer zone and long breakthrough time and, its adsorption capacity depended on the microporosity. Compared with single component adsorption, the amount adsorbed $CO_2$ on ACF increased by the roll-up of $CH_4$ in mixed gases. The adsorption selectivity increased as now rate and $CO_2$ concentration of mixed gases increased, showing 5.2 selectivity for 75% $CO_2$ concentration.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.7
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• pp.618-623
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• 2006

Hydrogenated Diamond-like carbon (DLC) films were prepared by the radio frequency plasma enhanced chemical vapor deposition (RF PECVD) method on silicon substrates using methane $(CH_4)$ and hydrogen $(H_2)$ gas. The wear track on the DLC films was examined after the ball-on disk (BOD) measurement with a Raman mapping method. The BOD measurement of the DLC films was performed for 1 to 3 hours with a 1-hour step time. The sliding traces on the hydrogenated DLC film after the BOD measurement were also observed using an optical microscope. The surface roughness and cross-sectional images of the wear track were obtained using an atomic force microscope (AFM). The novel Raman mapping method effectively shows the graphitization of DLC films of $300{\mu}m\times300{\mu}m$ area according to the sliding time by G-peak positions (intensities) and $I_D/I_G$ ratios.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.6
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• pp.171-178
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• 2006

The performance in the practical combustion system including reciprocating engines and gas turbine combustors is being much governed by turbulent reacting flow that is often analyzed by both a laminar flamelets concept and flame interaction. The characteristics of laminar flame interaction have been investigated numerically to provide basic understanding of wrinkled turbulent flames under concentration interaction resulting from inhomogeneity in fuel-air mixing, especially focused on the transition of flame characteristics such as diffusion flame, partially premixed diffusion flame, and triple-layer flame by the variation in the degree of premixedness. The extinction stretch rates to the premixedness have also been obtained in this paper. The boundary defining the regime of the existence of triple-layer flames as functions of both stretch rate and premixedness has been determined which agrees well with previously reported experiment measuring OH radical concentration peaks based on PLIF.

• Transactions of the Korean hydrogen and new energy society
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• v.25 no.6
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• pp.586-593
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• 2014

Limited sources of fossil fuels and also global climate changes caused by $CO_2$ emissions are currently discussed around the world. As a renewable, carbon neutral and widely available energy source, biogas is regarded as a promising alternative to fossil fuels. In this study, a plasma dump reformer was proposed to produce $H_2$-rich synthesis gas by a model biogas. The three-phase gliding arc plasma and dump combustor were combined. Screening studies were carried out with the parameter of a dump injector flow rate, water feeding flow rate, air ratio, biogas component ratio and input power. As the results, methane conversion rate, carbon dioxide conversion rate, hydrogen selectivity, carbon monoxide yield at the optimum conditions were achieved to 98%, 69%, 42%, 24.7%, respectively.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.9
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• pp.658-665
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• 2009

Lean premixed combustors are used for significant NOx reduction which one of issues in current gas turbine combustor. This study was investigated to estimate the effects of the unmixedness of fuel-air, equivalence ratio on the instability mechanism, NOx emission and combustion oscillation in a lean premixed combustor. The experiments were conducted in a dump combustor at atmospheric pressure conditions using methane as fuel. The swirler angle was $45^{\circ}$, the degrees of fuel-air mixing were 0, 50 and 100 and inlet temperature was 650K. The equivalence ratio was ranging from 0.5 to 0.8. This paper shows that NOx emission was increased when the degree of fuel-air mixing is increased in same equivalence ratio and when equivalence ratio is increased. And the range of the combustion instability was enlarged as a function of increasing of the degree of fuel-air mixing.