• Proceedings of the SAREK Conference
• /
• 2009.06a
• /
• pp.928-933
• /
• 2009

The purpose of this study is to examine the energy consumption, carbon dioxide emission & energy cost of district heating using sewage source. The annual TOE of heat pump using sewage source save 37.1 percent than city gas boiler. And annual carbon dioxide emission of heat pump cut down 41.3 percent than city gas boiler. If it charges the rate schedule for district heating to apartment resident, collected amount are 3,127,170 thousand won. As energy cost of heat pump & circulation pump are 1,378,072 thousand won. the profits are 1,749,098 thousand won. As payback period is 8.97years, applicability is low level. However, it has advantages in energy consumption, carbon dioxide emission & energy cost. Therefore, it needs to proceed through government assistance.

• Journal of Environmental Science International
• /
• v.13 no.10
• /
• pp.911-919
• /
• 2004

The purpose of this research was evaluated economical effect to apply alternative external carbon source. Conventional activated sludge process in municipal wastewater treatment plant was adapted and introduced to Biological nutrient removal processes to meet the newly enforced effluent quality standard for nutrient removal in Korea. Low $COD/NH_4^+-N$ ratio and higher nutrient concentration of influent characteristics force to inject external carbon source for denitrifying recycled nitrate. In the most case, methanol was used as external carbon source. But Methanol is expensive and very dangerous in handling. So we could find cheaper and safer external carbon source substituted methanol in last study. This alternative external carbon source is named RCS(recoverd carbon source) and a by-product of fine chemical product at chemical plant. When RCS was applied real municipal wastewater treatment plant, average $55\~65\%$ of T-N removal efficiency, 8.8mg/l of effluent T-N concentration, 11.3mg/l of effleunt COD concentration were obtained without effluent COD increase as against used methanol. To apply RCS in municipal wastewater treatment plant obtain approximately $\74.5%$ expenditure cost reduction in comparison with methanol dosage cost.

• Journal of Environmental Science International
• /
• v.21 no.3
• /
• pp.383-390
• /
• 2012

For the cost-effective biological nitrogen removal (BNR) process whose characteristics of influent have low COD/N ratios, the automatic control system for the addition of external carbon based on oxidation-reduction potential (ORP) data in an anoxic reactor has been developed. In this study, it was carried out with a pilot-scale Bardenpho process which was consisted of anoxic 1, aerobic 1, aerobic 2, anoxic 2, aerobic 3 tank and clarifier. Firstly, the correlation coefficient ($R^2$) of the dosage of external carbon source and ORP value was about 0.97. Consequently, the automatic control system using ORP showed that the dosage of external carbon source was decreased by about 20% compared with a stable dosage of 75 mg/L based on the COD/N ratio of the anoxic influent.

• Journal of Information Display
• /
• v.2 no.3
• /
• pp.48-53
• /
• 2001

Carbon nanotube emitters, prepared by screen printing, have demonstrated a great potential towards low-cost, largearea field emission displays. Carbon nanotube paste, essential to the screen printing technology, was formulated to exhibit low threshold electric fields as well as an emission uniformity over a large area. Two different types of triode structures, normal gate and undergate, have been investigated, leading us to the optimal structure designing. These carbon nanotube FEDs demonstrated color separation and high brightness over 300 $cd/m^2$ at a video-speed operation of moving images. Our recent developments are discussed in details.

• Journal of Environmental Science International
• /
• v.29 no.8
• /
• pp.819-826
• /
• 2020

Production of Bacterial Cellulose (BC) by Gluconacetobacter sp. A5 was studied in shaken culture using different cost-effective carbon sources and its structural and mechanical properties were evaluated. Glycerol showed the highest level (7.26 g/l) of BC production, which was about three times higher than the yield in glucose medium. BC production depended not only on the decrease in pH, but also on the ability of Gluconacetobacter sp. A5 to synthesize glucose from different carbon sources and then polymerize it into BC. All BC produced from different carbon sources exhibited a three-dimensional reticulated structure consisting of ultrafine cellulose fibriles. Carbon sources did not significantly change the microfibrile structure of the resulting BC. BC produced from glucose medium had the lowest water-holding capacity, while BC from molasses medium had the highest. XRD data revealed that all BC were cellulose type I, the same as typical native cellulose. The crystalline strength of BC produced in glucose medium was the highest, and that in molasses medium was the lowest. Our results suggest that glycerol could be a potential low-cost substrate for BC production, leading to the reduction in the production cost, and also to produce BC with different mechanical properties by selecting appropriate carbon source.

• 한국생물공학회:학술대회논문집
• /
• 2000.04a
• /
• pp.227-230
• /
• 2000

Batch cultivations of Anaerobiospirillum succiniciproducens have been systematically studied for the economical production of succinic acid from wood hydrolysate with corn steep liquor(CSL) as a nitrogen source. CSL was found to be an alternative complex nitrogen source for A. succiniciproducens when glucose and wood hydrolysate were used as carbon sources. Compared with polypeptone and/or yeast extract, CSL had similar effects on fermentation performance such as succinic acid yield and a ratio of succinic acid to acetic acid in the fermentation of wood hydrolysate as well as glucose. This means that succinic acid can be produced more economically from wood hydrolysate and CSL than relatively expensive carbon and nitrogen sources. Besides its low cost, the alternative medium served as a green technology for succinic acid production because it gives a net-zero effect on global warming.

• Progress in Superconductivity and Cryogenics
• /
• v.19 no.3
• /
• pp.40-43
• /
• 2017

Carbon coating approach is used to prepare carbon-doped $MgB_2$ bulk samples using low-cost naphthalene ($C_{10}H_8$) as a carbon source. The coating of carbon (C) on boron (B) powders was achieved by direct pyrolysis of naphthalene at $120^{\circ}C$ and then the C-coated B powders were mixed well with appropriate amount of Mg by solid state reaction method. X-ray diffraction analysis revealed that there is a noticeable shift in (100) and (110) Bragg reflections towards higher angles, while no shift was observed in (002) reflections for $MgB_2$ doped with carbon. As compared to un-doped $MgB_2$, a systematic enhancement in $J_c(H)$ properties with increasing carbon doping level was observed for naphthalene-derived C-doped $MgB_2$ samples. The substantial enhancement in $J_c$ is most likely due to the incorporation of C into $MgB_2$ lattice and the reduction in crystallite size, as evidenced by the increase in the FWHM values for doped samples.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
• /
• v.12 no.2
• /
• pp.13-18
• /
• 2016

Energy saving has been main concern, thus government supporting policies which are based on Fundamentals of Low-carbon Green Growth Act', 'Green Building Support Act, have been prepared in Korea. The objective of this study is to estimate energy conservation effectiveness and economic advantage assuming that lighting equipments and heat source equipments would be retrofitted. Office building, which has total floor area of $30,000m^2$, was a subject of this study. From the estimations, electric rate will be decreased by 62,886,000 won per year due to lighting equipments retrofit, and gas rate will be decreased 11,141,000 won or 17,332,000 won per year due to heat source equipments retrofit (in case of COP 1.2 or 1.5). Payback period of each case that are calculated by energy saving cost and retrofit cost are estimated 27.9 year, 38.6 year and 29.2 year, thus economic supporting policies is necessary for effective energy saving in buildings. Meanwhile payback period of heat source equipment for new building is estimated 6.1 year and 8.3 year.

• 한국신재생에너지학회:학술대회논문집
• /
• 2010.06a
• /
• pp.244.1-244.1
• /
• 2010

Bio energy development by using Low Calorific Gas Turbine(LCGT) has been developed for New & Renewable energy source for next generation power system, low fuel and operating cost method by using the renewable energy source in landfill gas (LFG), Food Waste, water waste and Livestock biogas. Low calorific fuel purification by pretreatment system and carbon dioxide fixation by green house system are very important design target for evaluate optimum applications for bio energy. Main problems and accidents of Low Calorific Gas Turbine system was derived from bio fuel condition such as hydro sulfide concentration, siloxane level, moisture concentration and so on. Even if the quality of the bio fuel is not better than natural gas, LCGT system has the various fuel range and environmental friendly power system. The mechanical characterisitics of LCGT system is a high total efficiency (>70%), wide range of output power (30kW - 30MW class) and very clean emmission from power system (low NOx). Also, we can use co-generation system. A green house designed for four different carbon dioxide concentration from ambient air to 2000 ppm by utilizing the exhaust gas and hot water from LCGT system. We look forward to contribute the policy for Renewable Portfolio Standards(RPS) by using LCGT power system.

• Carbon letters
• /
• v.25
• /
• pp.103-112
• /
• 2018

Hierarchically porous, chemically activated carbon materials are readily derived from biomass using hydrothermal carbonization (HTC) and chemical activation processes. In this study, empty fruit bunches (EFB) were chosen as the carbon source due to their sustainability, high lignin-content, abundance, and low cost. The lignin content in the EFB was condensed and carbonized into a bulk non-porous solid via the HTC process, and then transformed into a hierarchical porous structure consisting of macro- and micropores by chemical activation. As confirmed by various characterization results, the optimum activation temperature for supercapacitor applications was determined to be $700^{\circ}C$. The enhanced capacitive performance is attributed to the textural property of the extremely high specific surface area of $2861.4m^2\;g^{-1}$. The prepared material exhibited hierarchical porosity and surface features with oxygen functionalities, such as carboxyl and hydroxyl groups, suitable for pseudocapacitance. Finally, the as-optimized nanoporous carbons exhibited remarkable capacitive performance, with a specific capacitance of $402.3F\;g^{-1}$ at $0.5A\;g^{-1}$, a good rate capability of 79.8% at current densities from $0.5A\;g^{-1}$ to $10A\;g^{-1}$, and excellent life cycle behavior of 10,000 cycles with 96.5% capacitance retention at $20A\;g^{-1}$.