• 생태와환경
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• 제34권3호통권95호
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• pp.166-174
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• 2001

소양호로 유입되는 유기탄소량을 측정하였으며, 유기탄소 부하량에 대한 유기물 기원의 기여도를 계산하기위해서 내부생성유기탄소와 외부기원유기탄소를 측정하였다. 내부생성유기탄소는 EOC를 고려한 식물플랑크톤의 1차생산력으로부터 계산하였으며, 외부기원유기탄소는 유입수의 유기탄소 농도와 양어장의 유기탄소 배출량으로부터 구하였다. 1차생산력은 가두리 양식장이 설치된 1987견부터 증가하여 1995견가지 높은 분포를 보였으며 가두리가 철거된 1998년 이후 급격히 감소하였다. 내부생성유기탄소와 외부기원유기탄소의 부하는 여름철에 집중되었으며, 7${\sim}$9월에 연간 부하량의 43.2%와 71.7%가 각각 유입되었다. 1차생산력은 여름철에 $1,000\;mgC\;m^{-2}\;d^{-1}$ 이상으로 증가하였으며 겨울철에 비교적낮았다. 식물플랑크톤의 EOC배출율도 1차생산이 증가하여 수체의 DOC농도가 높은 여름철에 높았다. 전체조사기간동안 내부생성과 외부기원유기물의 평균적인 기여도는 각각 총부하량의 53.6%와 46.4%를 차지하였다. EOC 배출율은 1차생산력의 4.4${\sim}$21.2%를 차지하였으며, 1차생산력 산정에서 식물플랑크톤의 EOC 배출율이 고려되어야 할 것으로 보인다.

• 한국물환경학회지
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• 제27권4호
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• pp.397-404
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• 2011

This research investigates the runoff characteristics of refractory organic matters from Kyongan river watershed. Samples were taken 27 times during dry season, 4 times during rain events and analyzed into flow rate, Dissolved Organic Carbon (DOC), Particulate Organic Carbon (POC), Refractory Dissolved Organic Carbon (R-DOC), Refractory Particulate Organic Carbon (R-POC). R-DOC during dry season was the lowest in winter and showed a rising tendency in spring and R-POC changes less than R-DOC. The mass loading of Refractory Total Organic Carbon (R-TOC) in summer takes approximately 80% of 1 year mass loading. During rainy season, EMC of R-DOC was similar to R-DOC in dry season. But maximum EMC of R-POC was 12 times higher than that of R-POC in dry season. Results of the survey show that enhanced management of R-DOC in dry season and R-POC in rainy season is needed.

• Environmental Engineering Research
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• 제14권4호
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• pp.238-242
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• 2009

This study investigated the effects of organic loading rates on simultaneous carbon and nitrogen removal in an innovative fixed-film aerobic bioreactor. The fixed-film bioreactor (FFB) was composed of a two-compartment aeration tank, in which a synthetic filamentous carrier was submerged as biofilm support media, and a settling tank which polyvinylidene media (Saran) was used as settling aid for suspended solids. Three different organic loading rates, ranging from 0.92-2.02 kg chemical oxygen demand/$m^3$/day were applied by varying hydraulic retention time (HRT). The total soluble organic carbon removal efficiencies were in the range of 90-97%. The removal efficiency of ammonia was found to be in the range of 70-84%. Total nitrogen removal efficiency was found to be in the range of 40-45%, which indicates that denitrification reactions occurred simultaneously in the attached biofilm on the fibrous media in the aeration tank. The settling performance of suspended solids was significantly improved due to the presence of Saran media in the settling compartment, even for a short HRT. The fixed-film aerobic bioreactor used in this study demonstrated efficient treatment efficiency even at higher organic loading rates and at short HRTs.

• Environmental Engineering Research
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• 제10권6호
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• pp.265-268
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• 2005

A batch-type study was conducted to investigate the phosphorus release and uptake under anaerobic and aerobic conditions according to organic loading changes. As organic loading increased, anaerobic P release increased but aerobic P uptake decreased. Where organic carbon contents remain high in aerobic conditions, PHB consumption within the microbial cells diminished, therefore it was found that in order to enhance P uptake rate, it should reach the endogenous growth stage where the entire organic loading was consumed.

• 한국환경과학회지
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• 제15권10호
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• pp.975-982
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• 2006

This study has been conducted to optimum operating conditions for effective acid fermentation according to OLR(organic loading rate) in the mesophilic and thermophilic acid fermentation process. The results are summarized as follows. In order to obtain reasonable acid fermentation efficiency in performing acid fermentation of food wastes in thermophilic condition, organic loading rate was required below 20 gVS/L.d. As $SCOD_{Cr}/TKN,\;SCOD_{Cr}/T-P$ of thermophilic acid fermented food wastes In organic loading rate 20 gVS/L.d were 18.9, 73.4 respectively, it was possible to utilize as external carbon source for denitrification in sewage treatment plant after solid-liquid separation as well as co-digestion of fermented food wastes and sewage sludge.

• 한국환경과학회지
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• 제21권1호
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• pp.1-9
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• 2012

A thermal-optical transmittance carbon analyzer has been developed to determine particulate organic (OC) and elemental (EC) carbon. Several analysis factors affecting the sensitivity of OC and EC determination were investigated for the carbon analyzer. Although total carbon (TC) is usually consistent in the determination, OC and EC split is sensitive to adopted analysis protocol. In this study the maximum temperature in oxygen-free He in the analysis was examined as a main cause of the uncertainty. Prior to the sensitivity analysis consistency in OC-EC determination of the carbon analyzer and the uniformity of carbonaceous aerosol loading on a sampled filter were checked to be in acceptable range. EC/TC ratios were slightly decreased with increasing the maximum temperature between $550-800^{\circ}C$. For the increase of maximum temperature from $500^{\circ}C$ to $800^{\circ}C$, the EC/TC ratio was lowered by 4.65-5.61% for TC loading of 13-44 ${\mu}g/cm^2$ with more decrease at higher loading. OC and EC determination was not influenced by trace amount of oxygen in pure He (>99.999%), which is typically used in OC and EC analysis. The facing of sample loaded surface to incident laser beam showed negligible influence in the OC-EC split, but it caused elevated PC fraction in OC for forward facing relative to backward facing.

• Carbon letters
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• 제15권1호
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• pp.67-70
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• 2014

In this work, nanocomposites of epoxy resin and chemically reduced graphene oxide (RGO) were prepared by thermal curing process. X-ray diffractions confirmed the microstructural properties of RGO. Differential scanning calorimetry was used to evaluate the curing behaviors of RGO/epoxy nanocomposites with different RGO loading amounts. We investigated the effect of RGO loading amounts on the mechanical properties of the epoxy nanocomposites. It was found that the presence of RGO improved both flexural strength and modulus of the epoxy nanocomposites till the RGO loading reached 0.4 wt%, and then decreased. The optimum loading achieved about 24.5 and 25.7% improvements, respectively, compared to the neat-epoxy composites. The observed mechanical reinforcement might be an enhancement of mechanical interlocking between the epoxy matrix and RGO due to the unique planar structures.

• Carbon letters
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• 제18권
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• pp.24-29
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• 2016

High pollutant-loading capacities (up to 319 times its own weight) are achieved by three-dimensional (3D) macroporous, slightly reduced graphene oxide (srGO) sorbents, which are prepared through ice-templating and consecutive thermal reduction. The reduction of the srGO is readily controlled by heating time under a mild condition (at 1 10⁻² Torr and 200℃). The saturated sorption capacity of the hydrophilic srGO sorbent (thermally reduced for 1 h) could not be improved further even though the samples were reduced for 10 h to achieve the hydrophobic surface. The large meso- and macroporosity of the srGO sorbent, which is achieved by removing the residual water and the hydroxyl groups, is crucial for achieving the enhanced capacity. In particular, a systematic study on absorption parameters indicates that the open porosity of the 3D srGO sorbents significantly contributes to the physical loading of oils and organic solvents on the hydrophilic surface. Therefore, this study provides insight into the absorption behavior of highly macroporous graphene-based macrostructures and hence paves the way to development of promising next-generation sorbents for removal of oils and organic solvent pollutants.

• 대한화학회지
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• 제68권2호
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• pp.87-92
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• 2024

The commercialization of rechargeable metal-air batteries is extremely desirable but designing stable oxygen reduction reaction (ORR) catalysts with non-noble metal still has faced challenges to replace platinum-based catalysts. The nonnoble metal catalysts for ORR were prepared to improve the catalytic performance and stability by the thermal decomposition of ZIF-8 with optimum cobalt loading. The porous carbon was obtained by the calcination of ZIF-8 and different loading amounts of Co nanoparticles were anchored onto porous carbon forming a Co/PC catalyst. Co/PC composite shows a significant increase in the ORR value of current and stability (500 h) due to the good electronic conductive PCN support and optimum cobalt metal loading. The significantly improved catalytic performance is ascribed to the chemical structure, synergistic effects, porous carbon networks, and rich active sites. This method develops a new pathway for a highly active and advantageous catalyst for electrochemical devices.

• 한국습지학회지
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• 제19권3호
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• pp.353-358
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• 2017

2,600만 수도권 시민들의 식수원인 한강수계의 경우 수질관리를 위해 비점오염원에 대한 관리가 중요하며 특히 비점오염원이 주요 원인인 유기물질 및 난분해성 물질에 대한 조사가 필요하다. 이번 연구에서는 한강 수계의 주요 3개 하천(남한강, 북한강, 경안천)의 연간 비강우시 난분해성 유기물질을 포함한 유기물질의 유출특성을 연구하였다. 연구결과 유기물질 및 난분해성 물질의 경우 용존성 물질의 비율이 높았으며 전체 부하량중 여름철에 대부분의 부하량이 가장 많았다. 각 하천별 유기물질 및 난분해성 물질의 연간 부하량의 경우 유역면적에 비례하여 남한강, 북한강, 경안천 순서로 나타났다. 각 유역 면적 당 부하량 산정결과 TOC의 경우 경안천, 남한강, 북한강 순서로 나타났으며, R-TOC의 경우 비교적 일정한 유출특성을 보였다.