• Journal of the Korean Society of Visualization
• /
• v.14 no.3
• /
• pp.51-58
• /
• 2016

New concept spark plug was developed to study its influence on the combustion characteristics of SI engine. It has pre-ignition chamber at the lower end of spark plug and flame hole, in which fresh mixture gas can be put in through the flame hole without any fuel supply system. This spark plug was tested in a single cylinder engine dynamometer for different air fuel ratio to measure the fuel consumption rate, emission gases, and MBT timing. And constant volume combustion chamber was made to understand flame characteristics of spark plug. New spark plug induced fast burn compared to the conventional spark plug and its effects were increased in lean air fuel ratio. Pre-ignition chamber spark plug with 5 holes which had adjusted size was more stable and effective in combustion performance than pre-ignition chamber spark plug with 1 hole. And its effects showed larger differences in lean air fuel ratio than stoichiometric condition. Flame kernel and flame growth process of conventional spark plug and pre-ignition chamber spark plug studied by flame visualization of schlieren method.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.21 no.9
• /
• pp.947-954
• /
• 2010

The decision of threat target in the MWR(Missile Warning Radar) of GVES(Ground Vehicle Equipment System) such as MBT(Main Battle Tank) is very important. Threat decision is judged by angular rate and the accurate azimuth calculation for good threat decision is very important. The angular rate is dependent upon the direction of an approaching target. The target is classified into a threat or non-threat using a boundary condition of the angular rate. This paper presents the eighth azimuth calculation methods and compares the results.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.11 no.2
• /
• pp.63-68
• /
• 2003

The purpose of this study was to investigate reduction of exhaust gas temperature in LPG conversion engine from diesel. A conventional diesel engine was modified to a LPG(Liquified Petroleum Gas) engine that diesel fuel injection pump was replaced by the LPG fuel system. The research was peformed with measurement of exhaust gas temperature by varying spark ignition timing, air-fuel ratio, compression ratio, EGR ratio and different compositions of butane and propane. The major conclusion of this work were followed. (i) Exhaust gas temperature was decreased and power was increased with the advanced spark ignition timing. (ii) Exhaust gas temperature was decreased with lean and rich air-fuel ratio. (iii)Exhaust gas temperature was decreased and power was increased with the higher compression ratio. (iv) Engine power and exhaust temperature were not influenced by varied butane/propane fuel compositions. (v) Finally, one of the important parameters in reduction of exhaust gas temperature is spark ignition timing among the parameters in this study.

• Journal of Korean Society of Environmental Engineers
• /
• v.32 no.10
• /
• pp.942-948
• /
• 2010

To predict the potential reduction of $CH_4$ by recovering several types of wastes as of reusable energy sources like RDF, the $CH_4$ emission for each type of waste from Landfill Site 3 of SUDOKWON Landfill was estimated for the period of 2017 to 2024. Without any recovering effort on types of wastes being disposed of at the Landfill, there are producing a total of $526{\times}10^6\;Nm^3$ of $CH_4$; municipal waste of $337{\times}10^6\;Nm^3$, construction waste of $178{\times}10^6\;Nm^3$, and facility waste of $11{\times}10^6\;Nm^3$. It composed of 41.5% to that observed from 2002 to 2009. With properly retrieved by MT(Mechanical Treatment), it released a total of $158{\times}10^6\;Nm^3$ $CH_4$; $127{\times}10^6\;Nm^3$, $28{\times}10^6\;Nm^3$, and $4{\times}10^6\;Nm^3$, respectively. Additionally, when biologically degradable residues can be fully treated by MBT (Mechanical & Biological Treatment) system, the total amount of $CH_4$ emitted from the site will be lowered down as low as $115{\times}10^6\;Nm^3$, which is comparably lower showing only 21.8% to that for without any energy recovery practice. Futhermore, it is far less showing 9.1% to that obtained from 2002 to 2009. It can be decided that predictable amount of $CH_4$ emission reduced could be successfully accomplished and enhanced through ways of energy recovery efforts such as further scale adjustment of LFG treatment capacity in association with currently implemented practices in the landfill site.

• Animal cells and systems
• /
• v.11 no.1
• /
• pp.1-8
• /
• 2007

Recently, we have shown that some endocrine disruptors, heavy metals, organotins and azoles suppressed steroidogenic enzymes such as P450 side-chain cleavage enzyme (P450scc) and aromatase in bullfrog ovarian follicles. In the present study, by using an amphibian ovarian follicle culture system, we examined the effects of these endocrine disruptors on maturation and ovulation of oocytes from Rana dybowskii in vitro. Ovarian fragments or isolated follicles were cultured for 24 h in a medium containing frog pituitary homogenate (FPH) or progesterone ($P_{4}$) with or without endocrine disruptors, and oocyte maturation (germinal vesicle breakdown, GVBD) and ovulation were examined. Among the organotins, tributyltin (TBT) strongly inhibited both FPH-and $P_{4}-induced$ oocyte maturation ($ED_{50}$:0.6 and 0.7 ${\mu}M$, respectively); however, tetrabutyltin (TTBT) and dibutyltin (DBT) showed only partial suppression, while monobutyltin (MBT) showed no inhibitory effect. All of the organotins suppressed $P_{4}-induced$ oocyte ovulation very effectively at a low concentration, and TBT and DBT exerted an inhibitory effect on FPH-induced ovulation. Among the heavy metals, mercury (Hg), cadmium (Cd) and cobalt (Co) were very effective in inhibiting FPH-induced oocyte maturation and ovulation, while lead (Pb), arsenite (As) and zinc (Zn) were less effective. However, all of the heavy metals suppressed FPH-induced oocyte ovulation at a high dose ($100{\mu}M$). Among the azoles, itraconazole (ICZ), ketoconazole (KCZ) and clotrimazole (CTZ) effectively inhibited FPH-induced oocyte maturation and ovulation, while econazole (ECZ), miconazole (MCZ) and fluconazole (FCZ) were considerably less effective. These results demonstrated that the abovementioned endocrine disruptors exhibited differential effects on oocyte maturation and ovulation in amphibian follicles and that the frog ovarian culture system could be used as an effective experimental tool to screen and evaluate the toxicity of various endocrine disruptors in vitro.

• Journal of the Korean Institute of Gas
• /
• v.22 no.6
• /
• pp.34-39
• /
• 2018

Natural gas is attracting attention as an alternative to existing fossil fuels. Natural gas has a high octane number. Therefore, knocking does not occur even if the compression ratio is increased, so that the thermal efficiency and the output can be improved. And it is relatively easy to apply the natural gas supply system to the internal combustion engine hardware system. In this study, a gasoline direct injection turbo engine was converted into a natural gas port injection type turbo engine. Therefore, the combustion and performance of the engine are measured and compared comprehensively in the region where the turbo operates.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.11 no.1
• /
• pp.42-48
• /
• 2003

LPG has been a broad concern of pro-environmental alternative fuel for vehicles. Recently, the new Liquid Phase LPG Injection(LPLI) system extends the limit of power of LPG engine and gives a chance to substitute LPG engine for diesel engine of heavy duty vehicles that are the main resources of air pollution in urban area. Large bore size of heavy duty LPG engine derives a serious knock problem. To find an optimal MBT conditions, it is necessary to know how the flame develops in the combustion chamber and find where the knock positions are. In this study. the ion-probe head gasket was used to estimate the knock position. Inverse operation of the ion-probe signal provides the flame developing characteristics. The further the position is from the spark plug, the later the flame arrives and the more times knock occurs. The main factor that effects knock position is inferred a flor situation of mixed gas in the combustion chamber.

• Journal of the Korean Institute of Gas
• /
• v.15 no.2
• /
• pp.63-68
• /
• 2011

As an effective utilization of biomass, organic wastes and coal, attention has been made to use syngas to a reciprocating engine to generate power. However, significant component variation of syngas depending upon origin and gasification conditions, and its lower heating value than that of LPG and CNG can create difficulties in stable engine operation. Thus it is necessary to address these issues in order to successfully develop power generation engines. As a primary step to resolve these problems, effects of H2 content variation in syngas on engine performance and emission characteristics were discussed in this study. The results show that as H2 % in syngas increases, more stable combustion was achieved with retarded MBT spark timing and engine efficiency becomes maximum with syngas of 10% H2. In addition, NOx emission increased while THC emission decreased as H2 % rises in the syngas.

• Journal of the Korean Institute of Gas
• /
• v.16 no.5
• /
• pp.14-20
• /
• 2012

Biogas can be obtained from biogenic materials through an anaerobic digestion process. Since biogas has low calorific value and its composition significantly varies, appropriate combustion strategies need to be established to obtain stable combustion in engine applications. In this study, efforts have been made to investigate the effects of inert gas composition variations on engine performance and emissions. Results show that the MBT spark timing was advanced and $NO_x$ was reduced as the inert gas in the biogas rose. Moreover, $NO_x$ emission drop in $CO_2$ diluted biogas was more significant than that of $N_2$ due to higher heat capacity of $CO_2$, while THC emissions showed the opposite tendency. Thermal efficiency was increased in $N_2$ case with elevation of $N_2$ due to the decreased heat loss and PMEP. However, there is no difference in $CO_2$ case because of deteriorated flame propagation speed.