• Journal of the Korea Organic Resources Recycling Association
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• v.26 no.1
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• pp.47-53
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• 2018

Recovery of lactic acid from fermentation broth using chemical precipitation was investigated with various chemicals. Effects of chemical types, mixing speeds, settling duration, and solvent addition were evaluated to improve the recovery rates of lactic acid. Overall, recovery efficiencies increased as the dosage of chemicals increased. Recovery rate of lactic acid by CaO was higher than those of $Ca(OH)_2$ and $CaCO_3$. Recovery of lactic acid increased by 48% under the optimized reaction conditions which included a mixing speed at 180 rpm, a settling duration of 24 h, and addition of ethanol at 25%(v/v). Practical application needs to consider types and concentrations of other organic acids as well as lactic acid. Based upon the results of fluorescence excitation emission matrix (FEEM), size exclusion chromatography (SEC), characteristics of recovered lactic acid were same as that in the fermentation broth.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.7
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• pp.1032-1038
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• 2017

Recently, regulation on carbon emissions has been strengthened according to the new climate change convention (COP21) held in Paris, and then Korea has decided to reduce CO2 emissions by 37% until 2030. As one of countermeasures, the government has energetically performed demonstration projects of island micro-grid including solar power, wind power and energy storage system. However, in order to smoothly introduce island micro-grid, it is a critical issue to carry out the economic evaluation for power utility aspect and independent power producer aspect. Therefore, this paper proposes economic evaluation algorithms of island micro-grid which are based on the present worth method, considering cost and benefit factors in the aspect of both sides. Firstly, in case of power utility this paper proposes algorithm to estimate a period of return on investment according to the introduction capacity of distributed generators replacing diesel generator. And also, in case of independent power producer, this paper proposes evaluation algorithm to estimate weighting factor of SMP and benefit rate based on break-even point related with cost and benefit. From a case study result on real island micro-grid model, it is confirmed that proposed algorithms are useful and practical for the economic evaluation of island micro-grid.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.1
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• pp.193-200
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• 2007

Natural gas is one of the most promising alternatives to gasoline and diesel fuels because of its lower harmful emissions, including $CO_2$, and high thermal efficiency. In particular, natural gas is seen as an alternative fuel for heavy-duty Diesel Engines because of the lower resulting emissions of PM, $CO_2$ and $NO_x$. Almost all CNG vehicles use the PFI-type Engine. However, PFI-type CNG Engines have a lower brake horse power, because of reduced volumetric efficiency and lower burning speed. This is a result of gaseous charge and the time losses increase as compared with the DI-type. This study was conducted to investigate the effect of injection conditions (early injection mode, late injection mode) on the combustion phenomena and performances in the or CNG Engine. A DI Diesel Engine with the same specifications used in a previous study was modified to a DI CNG Engine, and injection pressure was constantly kept at 60bar by a two-stage pressure-reducing type regulator. In this study, excess air ratios were varied from 1.0 to the lean limit, at the load conditions 50% throttle open rate and 1700rpm. The combustion characteristics of the or CNG Engine - such as in-cylinder pressure, indicated thermal efficiency, cycle-by-cycle variation, combustion duration and emissions - were investigated. Through this method, it was possible to verify that the combustion duration, the lean limit and the emissions were improved by control of injection timing and the stratified mixture conditions. And combustion duration is affected by not only excess air ratio, injection timing and position of piston but gas flow condition.

• Asian-Australasian Journal of Animal Sciences
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• v.27 no.4
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• pp.592-599
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• 2014

This study presents trends and projected estimates of methane and nitrous oxide emissions from livestock of India vis-$\grave{a}$-vis world and developing countries over the period 1961 to 2010 estimated based on IPCC guidelines. World enteric methane emission (EME) increased by 54.3% (61.5 to $94.9{\times}10^9kg$ annually) from the year 1961 to 2010, and the highest annual growth rate (AGR) was noted for goat (2.0%), followed by buffalo (1.57%) and swine (1.53%). Global EME is projected to increase to $120{\times}10^9kg$ by 2050. The percentage increase in EME by Indian livestock was greater than world livestock (70.6% vs 54.3%) between the years 1961 to 2010, and AGR was highest for goat (1.91%), followed by buffalo (1.55%), swine (1.28%), sheep (1.25%) and cattle (0.70%). In India, total EME was projected to grow by $18.8{\times}10^9kg$ in 2050. Global methane emission from manure (MEM) increased from $6.81{\times}10^9kg$ in 1961 to $11.4{\times}10^9kg$ in 2010 (an increase of 67.6%), and is projected to grow to $15{\times}10^9kg$ by 2050. In India, the annual MEM increased from $0.52{\times}10^9kg$ to $1.1{\times}10^9kg$ (with an AGR of 1.57%) in this period, which could increase to $1.54{\times}10^9kg$ in 2050. Nitrous oxide emission from manure in India could be $21.4{\times}10^6kg$ in 2050 from $15.3{\times}10^6kg$ in 2010. The AGR of global GHG emissions changed a small extent (only 0.11%) from developed countries, but increased drastically (1.23%) for developing countries between the periods of 1961 to 2010. Major contributions to world GHG came from cattle (79.3%), swine (9.57%) and sheep (7.40%), and for developing countries from cattle (68.3%), buffalo (13.7%) and goat (5.4%). The increase of GHG emissions by Indian livestock was less (74% vs 82% over the period of 1961 to 2010) than the developing countries. With this trend, world GHG emissions could reach $3,520{\times}10^9kg$ $CO_2$-eq by 2050 due to animal population growth driven by increased demands for meat and dairy products in the world.

• Journal of radiological science and technology
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• v.16 no.1
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• pp.107-115
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• 1993

In this study, to develop highly sensitive radiation sensors, $CaSO_4$ : Tm phosphors and its disc-type TLD elements embedded PTFE(polytetrafluoroethylene) are fabricated. The highest sensitivity of $CaSO_4$ : Tm phosphors is obtained when phosphors have been doped with 0.5mol % Tm and sintered in atmosphere at $600^{\circ}C$ for two hours. Fabricated disc-type elements are made from a homogeneous mixture of phosphors and PTFE powder. They are first cold-pressed and then polymerized at $370^{\circ}C$ in air for one hour. The dose dependence of the prepared $CaSO_4$ : Tm TLD radiation sensors is linear within the range of $100{\mu}Gy{\sim}10Gy$ for X-rays and ${\gamma}-rays$. The response of $CaSO_4$ : Tm to 30keV X-rays is ten times higher than that of 1.25MeV $^{60}Co\;{\gamma}-rays$. The fading rate of the main peak is about 2% per a month. The spectral peaks of TL emission spectrum are at about 350nm and 475nm. The $CaSO_4$ : Tm TLD radiation sensors prepared in this work may be used as radiation dosimeter for personal and environmental monitoring because of their high sensitivity and little fading.

• KIEAE Journal
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• v.10 no.1
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• pp.19-24
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• 2010

Modern people are spending most of time in interior area. Indoor air environmental problem is one of the most effective factors influenceable to human health. Furthermore, saving energy and making ventilation system for pleasant indoor environment are necessary when it is faced shortage of energy over the world. In our country's case, it is already imposed that required quantity of air ventilation in buildings is 0.7 times per hour on "The regulation on building engineering system". As on the rise of the interests about Indoor air environment, Heat and Carbon dioxide emissions from User's metabolism, activity, furniture, and construction materials etc. could be the causes of Indoor air pollution. If these materials stays in Indoor air for so long, it could directly influence the user's health condition with a disease. As of building's sterilization improved that raised more mechanical ventilation. It also leads much energy waste in a period of high price of fossil fuel. Therefore, the way that saves energy and effective control of indoor ventilation is urgently needed. So, this study places the purpose on validating volume of indoor ventilation and user's comfortable degree by comparison CO2 emission rate through changing floor temperature.

• Journal of ILASS-Korea
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• v.16 no.3
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• pp.119-125
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• 2011

Due to the oxygen contents in biodiesel, application of the fuel to compression ignition engines has significant advantages in terms of lowering PM formation in the combustion chamber. In recent days, considerable studies have been performed to extend the low temperature combustion regime in diesel engines by applying biodiesel fuel. In this work, low temperature combustion characteristics of biodiesel blends in dilution controlled regime were investigated at a fixed engine operating condition in a single cylinder diesel engine, and the comparisons of engine performances and emission characteristics between biodiesel and conventional diesel fuel were carried out. Results show that low temperature combustion can be achieved at $O_2$ concentration of around 7~8% for both biodiesel and diesel fuels. Especially, by use of biodiesel, noticeable reduction (maximum 50% of smoke was observed at low and middle loads compared to conventional diesel fuel. In addition, THC(total hydrocarbon) and CO(Carbon monoxide) emissions decreased by substantial amounts for biodiesel fuel. Results also indicate that even though about 10% loss of engine power as well as 14% increase of fuel consumption rate was observed due to lower LHV(lower heating value) of biodiesel, thermal efficiencies for biodiesel fuel were slightly elevated because of power recovery phenomenon.

• Korean Chemical Engineering Research
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• v.47 no.5
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• pp.580-586
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• 2009

In this study, co-combustion characteristics of Chinese bituminous coal and North Korean anthracite were investigated using a 2 MWe scale circulating fluidized bed power plant. At first, the combustion efficiency of bituminous coal of China and Australia as a function of excess air ratio and temperature were observed. The results showed that the combustion efficiency was influenced by particle size and volatile content of coal, the combustion efficiency of Chinese bituminous coal was over 99.5%. The unburned carbon particles from fly ash and bottom ash were a content 5~7% and 0.3%, respectively. The combustion efficiency with the mixture ratio 20% of bituminous coal and anthracite decreased over 5% because of the increase of entrained particles by a small average particle size of anthracite in the combustor. However, the outlet concentration of $SO_2$ and $NO_x$ was not changed remarkably. The concentrations of the typical air pollutants such as $NO_x$ and $SO_2$ were 200~250 ppm($O_2$ 6%), 100~320 ppm($O_2$ 6%) respectively. The outlet concentration of $NO_x$ was decreased to 30~65% with $NH_3$ supplying rate of 2~13 l/min in SCR process. The $SO_x$ removal efficiency was up to 70% by in-furnace desulfurization using limestone with Ca/S molar of approximately 6.5. With wet scrubbing using $Mg(OH)_2$ as absorbent, the $SO_x$ removal efficiency reached 100% under near pH 5.0 of scrubbing liquid.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.9
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• pp.762-767
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• 2016

High thermal efficiency and the ability to use various types of fuel are a few of the many advantages of diesel engines. However, a major disadvantage is that their exhaust emissions are more harmful to humans and the environment than that of conventional engine. Consequently, the provisions of the international emissions standards for diesel engine equipped passenger cars, commercial vehicles, and ships have become more stringent. These standards include the EU Euro 6, the IMO MEPC Tier 3, and the US EPA Tier 4. Ryu et al. published a study that applied fuel additives to two-stroke diesel engines. In this study, a four-stroke diesel engine using diesel oil for a generator is utilized as the test subject, and an experiment is performed to verify whether fuel additive can be used to improve performance and exhaust emissions. In addition, this experimental study presents research results for the application of fuel additives in both two-stroke and four-stroke diesel engines. The experimental results were compared and analyzed by placing an oil-soluble calcium-based organometallic compound in diesel oil. The results confirmed that the addition of fuel additive improved the performance (fuel consumption rate, exhaust gas temperature) and exhaust emissions (NOx, CO) of the diesel engine.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.14 no.1
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• pp.77-84
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• 2015

In 2011, greenhouse gas emissions of transport sector were 85.04 million $tonCO_2eq$ and road emissions accounted for 95% of total emissions in the transport sector. There are few innovative technologies to reduce greenhouse gas emissions aside from eco-driving education and public relation program. Therefore, this paper focused on analyzing optimal acceleration by certain road grades and suggested fuel-efficient driving method for various uphill sections. Scenarios were established by driving modes. Speed profiles were generated by scenarios and speed variations. Each speed profile applied to Comprehensive Modal Emission Model and then each fuel consumption was estimated. Driving mode and speed variation that minimized fuel consumption were driven according to grade percent and uphill distance. When driving in the eco-friendly mode of the driving and speed variation, reduction rate of fuel consumption was evaluated by comparison between eco-driving and cruise control mode. When a vehicle drove under eco-driving mode at 100kph, 90kph and 80kph on uphill road, fuel consumptions were reduced by 33.9%, 30.8% and 5.3%, respectively.