• Transactions of the Korean hydrogen and new energy society
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• v.23 no.4
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• pp.373-381
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• 2012

To determine the performance characteristics of motorcycle engine using biogas for practical use, the intake system of a 110 cc motorcycle engine is properly modified to operate with biogas as a fuel. Biogas is a potentially renewable fuel for replacing gasoline in future, but it has high percentage of $CO_2$ that could lead to slow the burning rate of biogas-air mixture and cause instability in combustion. Thus, the performance characteristics of biogas-fueled motorcycle engines could be different from those of gasoline motorcycle engines. In this paper, the important parameters of performance characteristics (such as: power output, thermal efficiency, fuel consumption, exhaust emission,${\cdots}$) of biogas-fueled motorcycle engine are studied and estimated with change of engine speed and load. The obtained results when operating with biogas are used to compare with that of gasoline fuel under the same operating conditions. Engine speed in the experimental is changed from 1500 rpm (idle-mode) up to 3500 rpm by a step of 500 rpm. Engine load is changed from zero to maximum load with the help of an exciting voltage device from generator-type dynamometer. The experimental results show that the tested engine operated with richer biogas-air mixture than that of gasoline-air mixture under the same test conditions. Biogas-fueled engine gives a higher fuel consumption and lower thermal efficiency under the same power output. Brake thermal efficiency of biogas engine is found to be about 3% lower than gasoline-fueled motorcycle engine for whole range of speed. Exhaust emission of biogas-fueled motorcycle engine (such as: CO, HC) is found to be lower than the limitation level of the emission standards of Vietnam for motorcycle engines (CO <4.5% HC <1200 ppm).

• Animal Bioscience
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• v.34 no.3_spc
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• pp.427-433
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• 2021

Objective: An experiment was conducted to investigate the effects of Achyranthes japonica extracts (AJE) on the growth performance, nutrient digestibility, fecal microbial shedding, and fecal gas emission of growing pigs. Methods: A total of 180 ([Landrace×Yorkshire]×Duroc) growing pigs with initial body weight (BW) of 23.94±1.54 kg were used in this study to investigate the effects of AJE as a feed additive. Dietary treatments included: i) CON (basal diet), ii) TRT1 (basal diet+0.05% AJE), and iii) TRT2 (basal diet+0.10% AJE). Results: As a result of the dietary supplementation of 0% to 0.10% AJE, a linear increase of BW (p<0.05) on d 21 and 42, a linear increase of average daily gain (ADG) (p<0.05) during d 21 to 42, a trend in linear increase of ADG (p<0.10) during d 0 to 21 and d 0 to 42, a linear increase of gain to feed ratio (G:F) (p<0.05) during d 0 to 42, and a tendency in the linear increase of G:F during d 21 to 42 were observed in this study. Additionally, dietary supplementation of 0% to 0.10% AJE had a linear increase (p<0.05) on the apparent total tract digestibility of dry matter (DM) and energy, a linear increase (p<0.05) on lactic acid bacteria counts, a tendency in reducing (linear effect, p<0.10) coliform bacteria counts, and a linear decrease (p<0.05) in excreta H2S emission content in growing pigs. Conclusion: In conclusion, the results suggested that AJE had the potential to enhance growth performance, DM and energy digestibility, and fecal lactic acid bacteria counts, and decrease the fecal coliform bacteria counts and excreta H2S emission in growing pigs.

• Journal of Radiation Protection and Research
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• v.49 no.1
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• pp.29-39
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• 2024

Background: The gamma emission tomography (GET) device has been reported a reliable technique to inspect partial defects within spent nuclear fuel (SNF) of pin-by-pin level. However, the existing GET devices have low accuracy owing to the high attenuation and scatter probability for SNF inspection condition. The purpose of this study is to design and optimize a Yonsei single-photon emission computed tomography version 2 (YSECT.v.2) for fast inspection of SNF in water storage by acquisition of high-quality tomographic images. Materials and Methods: Using Geant4 (Geant4 Collaboration) and DETECT-2000 (Glenn F. Knoll et al.) Monte Carlo simulation, the geometrical structure of the proposed device was determined and its performance was evaluated for the ¹³⁷Cs source in water. In a Geant4-based assessment, proposed device was compared with the International Atomic Energy Agency (IAEA)-authenticated device for the quality of tomographic images obtained for 12 fuel sources in a 14 × 14 Westinghouse-type fuel assembly. Results and Discussion: According to the results, the length, slit width, and septal width of the collimator were determined to be 65, 2.1, and 1.5 mm, respectively, and the material and length of the trapezoidal-shaped scintillator were determined to be gadolinium aluminum gallium garnet and 45 mm, respectively. Based on the results of performance comparison between the YSECT.v.2 and IAEA's device, the proposed device showed 200 times higher performance in gamma-detection sensitivity and similar source discrimination probability. Conclusion: In this study, we optimally designed the GET device for improving the SNF inspection accuracy and evaluated its performance. Our results show that the YSECT.v.2 device could be employed for SNF inspection.

• Journal of Environmental Impact Assessment
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• v.16 no.4
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• pp.301-310
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• 2007

For the improvement of air quality in the metropolitan area, Korea has enforced the air pollutant emission cap regulation from the 1st of July, 2007, and the companies that intend to install a new or an enlarged facility in the metropolitan area will be restricted. However, the current regulation on permission does not describe a standard of judgement distinctly. In this study, therefore, a method of permission on the installation of a new or an enlarged facility was developed by supplementing the law in force based on the foreign cases. To develop a specific permit regulation and procedure, the developed nations' cases such as US, Canada, EU were reviewed thoroughly. Also, an appropriate method was suggested to apply domestically for a new or an enlarged facility permit within the regulations of the metropolitan special law. The method consists of first, calculating the possible permit quantity from the difference between an estimated annual emission cap and the annual emission provided by the implementation plan in each region. Second, permitting a new or an enlarged facility construction within the difference of the emission between the regional emission cap and the implementation plan in 2014. Third, distributing emissions allowable to each performance year based on the regional emission cap and the implementation plan in 2014. Fourth, making use of the emission difference between the implementation plan and the performance result in each year. Considering the general domestic conditions, the convenience of the permit authority and permitted companies, the most reasonable method was to use the fourth. To enforce the suggested permit method in a more flexible way, parts of the related regulations need to be revised and continuous research and analysis on the results from the implemented system and on foreign cases is necessary to develop this method a suitable system for domestic conditions and to settle the air pollutant emission cap system.

• Korean Journal of Materials Research
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• v.14 no.8
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• pp.542-546
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• 2004

We report a new fabrication process for high performance triode type CNT field emitters and their superior electrical properties. The CNT-based triode-type field emitter structure was fabricated by the conventional semiconductor processes. The keys of the fabrication process are spin-on-glass coating and trim-and-leveling of the carbon nanotubes grown in trench structures by employing a chemical mechanical polishing process. They lead to strong adhesion and a uniform distance from the carbon nanotube tips to the electrode. The measured emission property of the arrays showed a remarkably uniform and high current density. The gate leakage current could be remarkably reduced by coating of thin $SiO_{2}$ insulating layer over the gate metal. The field enhancement factor(${\beta}$) and emission area(${\alpha}$) were calculated from the F-N plot. This process can be applicable to fabrication of high power CNT vacuum transistors with good electrical performance.

• Transactions of the Korean hydrogen and new energy society
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• v.28 no.1
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• pp.92-97
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• 2017

Kerosene (Coal oil) is a particularly attractive fuel because it is widely used to power jet engines of aircraft as jet fuel and some rocket engine. This paper describes the performance and emission characteristics according to the collant temperature of combustion chamber head of spark ignition engine fuelled with kerosene. As a result, the following knowledge is obtained. As the collant temperature of combustion chamber head is decreased, torque, volumetric efficiency and brake specific fuel consumption have been increased. When coolant temperature of combustion chamber lower, THC emission increased but CO and $NO_x$ emission decreased.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.1
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• pp.24-31
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• 2002

An experimental study was conducted to investigate the effects of EGR (Exhaust Gas Recirculation) variables on performance and emission characteristics in a 2-liter 4-cylinder spark-ignition LPG fuelled engine. The effects of EGR on the reduction of thermal loading at exhaust manifold were also investigated because the reduced gas temperature is desirable for the reliability of an engine in light of both thermal efficiency and material issue of exhaust manifold. The steady-state tests show that the brake thermal efficiency increased and the brake specific fuel consumption decreased with the increase of EGR rate in hot EGR and with the decrease of EGR temperature in case of cooled EGR, while the stable combustion was maintained. The increase of EGR rate or the decrease of EGR temperature results in the reduction of NOx emission even in the increase of HC emission. Furthermore, decreasing EGR temperature by $180^{\circ}C$ enabled the reduction of exhaust gas temperature by $15^{\circ}C$ in cooled EGR test at 1600rpm/370kPa BMEP operation, and consequently the reduction of thermal load at exhaust. The optimization strategy of EGR application is to be discussed by the investigation on the effect of geometrical characteristics of EGR-supplying pipe line.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.2
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• pp.98-104
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• 2011

The introduction of a diesel engine into the passenger car and light duty applications in the United States involves significant technical challenges for the automotive makers. This paper describes the SCR System optimization procedure for such a diesel engine application to meet Tier2 Bin5 emission regulation. A urea SCR system, a representative $NO_x$ reduction after-treatment technique, is applied to a 3.0 liter diesel engine. To achieve the maximum $NO_x$ reduction performance, the exhaust system layout was optimized using series of the computational fluid dynamics and the urea distribution uniformity test. Furthermore a comprehensive simulation model for the key factors influencing $NO_x$ reduction performance was developed and embedded in the Simulink/Matlab environment. This model was then applied to the urea SCR system and played a key role to shorten the time needed for SCR control parameter calibration. The potential of a urea SCR system for reducing diesel $NO_x$ emission is shown for FTP75 and US06 emission standard test cycle.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.2
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• pp.166-173
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• 2006

This study investigates a heavy duty diesel engine with swept vol. 12.6L, 4cycle-OHC type to verify the effects of the performance and exhaust gas emission according to the variable specifications of both swirl ratio and flow coefficient in inlet port, combustion bowl and fuel injection system. To meet the high BMEP and stringent exhaust emission standard, a turbocharger with wastegate and an intercooler were installed in the engine. Helical port, major design parameters for combustion chamber and electronic fuel injection pump with 1,000bar were reviewed and applied. Confirmation tests were also performed to meet the target value, $NO_x$ 5.0g/kWh and PM 0.1g/kWh of Euro3 exhaust emission legislation. The results of this study show that not only is it effective to use a relatively bigger bowl size for controlling rapid burning condition due to the decreased in-bowl swirl, but also to use a concave cam with double injection rates to decrease $NO_x$.

• Journal of ILASS-Korea
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• v.20 no.4
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• pp.254-260
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• 2015

The objective of this study is to investigate the effect of multi-hole nozzle on the performance of small CRDI engine. Combustion and exhaust emission characteristics of engine were studied by using CFD simulation with ECFM-3Z combustion model. The conditions of simulation were varied with nozzle geometry, injection timing and injection quantity. In addition, the results were compared in terms of combustion pressure, rate of heat release, $NO_x$ and soot emissions. It was found that combustion pressure was increased when injection timing was advanced. The rate of heat release of 6 hole nozzle was higher than that of 12 hole nozzle since the quantity of fuel impinged at the bottom of piston rim was different under different injection timing conditions. In the case of $NO_x$ emission, 6 hole nozzle generated more $NO_x$ emission than 12 hole nozzle. On the other hand, in the case of soot emission, 12 hole nozzle showed higher value than 6 hole nozzle because injected fuel droplets from multi-hole nozzle were coalesced.