• Journal of the Korean Institute of Gas
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• v.21 no.6
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• pp.1-7
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• 2017

This study is aimed to investigate the US code and European code on the evaluation of fuel economy of natural gas vehicles and deduce the formula suitable for domestic natural gas fuel. The fuel consumption formula have been derived by carbon balance relation between fuel composition and exhaust emission. The US code does not limit the composition of the test gas, but European code should be used the reference gases such as G20 and G23. In the case of NGV using domestic city gas, it is confirmed that the fuel economy determined by European code is 12% worse than that of US code because of difference of test gas. Also, a method of determining the fuel properties from the calorific value is proposed to evaluate the fuel economy of natural gas vehicles.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2003.10a
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• pp.50-53
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• 2003

Carbon nannofiber reinforced Cu matrix composite has potential applications for electrically conducting materials having high strength and electrical conductivity. In this study, we have developed fabrication technology of the nanocomposites using a liquid pressing process. The process is to use the low pressure for infiltration of Cu melt into carbon nanofiber mat as the Cu melt is pressurized directly. The minimum pressure required for infiltration was calculated from force balance equation, permeability measurement and compaction behavior of carbon nanofiber. Also, the melting temperature and the holding time have been optimized.

• Journal of Environmental Science International
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• v.5 no.4
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• pp.429-440
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• 1996

A global carbon cycle model (GCCM), that incorporates interaction among the terrestrial biosphere, ocean, and atmosphere, was developed to study the carbon cycling aid global carbon budget, especially due to anthropogenic $CO_2$ emission. The model that is based on C, 13C and 14C mass balance, was calibrated with the observed $CO_2$ concentration, $\delta$13C and $\Delta$14C in the atmosphere, Δ14C in the soil, and $\Delta$14C in the ocean. Also, GCCM was constrained by the literature values of oceanic carbon uptake and CO, emissions from deforestation. Inputs (forcing functions in the model) were the C, 13C and 14C as $CO_2$ emissions from fossil fuel use, and 14C injection into the stratosphere by bomb-tests. The simulated annual carbon budget of 1980s due to anthropoRenic $CO_2$ shows that the global sources were 5.43 Gt-C/yr from fossil fuel use and 0.91 Gt-C/yr from deforestation, and the sinks were 3.29 Gt-C/yr in the atmosphere, 0.90 Gt-C/yr in the terrestrial biosphere and 2.15 Gt-C/yr in the ocean. The terrestrial biosphere is currently at zero net exchange with the atmosphere, but carbon is lost cia organic carbon runoff to the ocean. The model could be utilized for a variety of studies in $CO_2$ policy and management, climate modeling, $CO_2$ impacts, and crop models.

• Environmental Engineering Research
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• v.25 no.3
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• pp.374-383
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• 2020

Landfill gas (LFG) emissions from a given amount of landfill waste depend on the carbon flows in the waste. The objective of this study was to more accurately estimate the first-order decay parameters through methane (CH₄) and carbon flow balances based on the analysis of a full-scale landfill with long-term data and detailed field records on LFG and leachate. The carbon storage factor for the case-study landfill was 0.055 g-degradable organic carbon (DOC) stored per g-wet waste and the amounts of DOC lost with the leachate were less than 1.3%. The appropriate CH₄ generation rate constant (k) for bulk waste was 0.24 y-1. The the CH₄ generation potential (L0) values ranged 33.7-46.7 m3-CH₄ Mg-1, based on the fraction of DOC that can decompose (DOCf) value of 0.40. Results show that CH4 and carbon flow balance methods can be used to estimate model parameters appropriately and to predict long-term carbon emissions from landfills.

• Korean Journal of Ecology and Environment
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• v.37 no.4 s.109
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• pp.448-454
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• 2004

In order to evaluate the water quality (N, P and C) and the biological mass balance of semi-enclosed brackish Lake Obuchi, Japan, an ecosystem model was developed and applied to the lake, using the flow field calculated by a hydrodynamic model. The time series data of the observed tide level, river discharge and meteorological parameters from January 2001 to December 2002 were incorporated as the parameters of the hydrodynamic model. Water quality and biomass balance were estimated by the ecosystem model, and simulated fluctuations In water quality agreed with our observations. The carbon contents of POC, phytoplankton and zooplankton in the lake were calculated by the model at an average 7200, 1500 and 22 kg, respectively, which somewhat agreed with our observations of POC (5900 kg), phytoplankton (3800kg), and zooplankton (150kg).

• Journal of Microbiology and Biotechnology
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• v.19 no.8
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• pp.836-844
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• 2009

A denitrification bacterium was isolated from riverbed soil and identified as Ochrobactrum sp., whose specific enzymes for denitrification metabolism were biochemically assayed or confirmed with specific coding genes. The denitrification activity of strain G3-1 was proportional to glucose/nitrate balance, which was consistent with the theoretical balance (0.5). The modified graphite felt cathode with neutral red, which functions as a solid electron mediator, enhanced the electron transfer from electrode to bacterial cell. The porous carbon anode was coated with a ceramic membrane and cellulose acetate film in order to permit the penetration of water molecules from the catholyte to the outside through anode, which functions as an air anode. A non-compartmented electrochemical bioreactor (NCEB) comprised of a solid electron mediator and an air anode was employed for cultivation of G3-1 cells. The intact G3-1 cells were immobilized in the solid electron mediator, by which denitrification activity was greatly increased at the lower glucose/nitrate balance than the theoretical balance (0.5). Metabolic stability of the intact G3-1 cells immobilized in the solid electron mediator was extended to 20 days, even at a glucose/nitrate balance of 0.1.

• Tribology and Lubricants
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• v.9 no.1
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• pp.62-69
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• 1993

Friction and wear behavior of a carbon/carbon composite material for aircraft brake material was experimentally investigated. Friction and wear test setup was designed and built for the experiment. Friction and wear tests were conducted under various sliding conditions. Friction coefficients were measured and processed by a data acquisition system and amount of wear measured by a balance. Stainless steel disk was used as the counterface material. Temperature was also measured by inserting thermocouple 2.5 mm beneath the sliding surface of the carbon/carbon composite specimen. Wear surfaces were observed by SEM, and analyzed by EDAX. The experimental results showed that sliding speed and normal force did not have significant effects on friction coefficient and wear factor of the composite. Temperature increase just below the surface was not large enough to cause any thermal degradation or oxidation which occurred at higher temperature when tested by TGA. Wear film was generated both on the specimen and on the counterface at relatively low sliding speed but cracks, grooves, and wear debris were observed at high sliding speed. Friction coefficient remained almost constant when the sliding speed or normal load was varied. It is believed that the adhesive and abrasive components contributed mainly to the friction coefficient. Wear behavior at low sliding speed was governed by wear film formation and adhesive wear mechanism. At high speed, fiber orientation, ploughing by counterface asperities, and fiber breakage dominated wear of the carbon/carbon composite.

• Korean Journal of Soil Science and Fertilizer
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• v.41 no.6
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• pp.408-414
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• 2008

Importance of climate change and its impact on agriculture and environment has increased with the rise Green House Gases (GHGs) concentration in the atmosphere. To slow down the speed of climate change many efforts have been applied in industrial sectors to reduce GHGs emission and to enhance carbon storage. In agricultural sector, many researches have been performed on GHGs emission reduction, but few on the role of carbon sink. In this study, we investigated carbon balance and soil carbon storage in agricultural field in the barley-red pepper and barley-soybean cropping system. With the system for automatic measuring of carbon dioxide, net ecosystem production(NEP) was estimated to be $6.3ton\;CO_2\;ha-1$ for N-P-K chemical fertilizer treatment plot and $10.6ton\;CO_2\;ha^{-1}$ for N-P-K chemical fertilizer with swine manure treatment plot in the barley-soybean rotation cropping. In the barley-red pepper rotation cropping, it was $12.0ton\;CO_2\;ha^{-1}$ for N-P-K chemical fertilizer treatment plot and $13.2ton\;CO_2\;ha^{-1}$ for N-P-K chemical fertilizer with swine manure treatment plot. Soil carbon storage rate was estimated to be $0.7ton\;C\;ha^{-1}$ for the barley-soybean cropping system and $0.5ton\;C\;ha^{-1}$ for barley-pepper cropping system. In appeared that agricultural lands may contribute to the greenhouse effect as a potential carbon sink preserving carbon into soil.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2015-2020
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• 2007

Diesel is an excellent candidate fuel for fuel cell applications due to its high hydrogen density and well-established infrastructure. But, it is hard to guarantee desirable performance of diesel reformer because diesel reforming has several problems such as sulfur poisoning of catalyst and carbon deposition. We have been focusing on diesel autothermal reforming(ATR) for substantial period. It is reported that ATR of diesel has several technical advantages such as relatively high efficiency and fuel conversion compared to steam reforming(SR) and partial oxidation(POX). In this paper, we investigate characteristics of diesel reforming under various ratios of reactants(oxygen to carbon ratio, steam to carbon ratio) for improvement of reforming performances(high reforming efficiency, high fuel conversion, low carbon deposition). We also exhibit calculated heat balance of autothermal reformer at each condition to help thermal management of SOFC system.

• Proceedings of The Korean Society of Agricultural and Forest Meteorology Conference
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• 2019.08a
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• pp.247-248
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• 2019