• 한국연소학회:학술대회논문집
• /
• 2003.12a
• /
• pp.83-88
• /
• 2003

The concept of lean-premixed combustion in gas turbine combustor operation has become a standard in recent years as an effective means to meet stringent environmental standards on NOx emissions. Various types of air-fuel premixer, which affect greatly NOx emission and stability of lean-premixed low NOx combustor, were investigated experimentally to reduce the NOx emission. One type of the premixers is selected by experiments and applied it to 70kW class lean-premixed gas turbine combustor. The exit temperature and emissions of CO and NOx were measured with equivalence ratios at ambient pressure. From the results, the emissions of CO and NOx were influenced by the type of air-fuel premixer. As the mixing length of air and fuel is longer, the NOx and CO emission were decreased in the primary reaction zone. Compared with of conventional combustor, the lean-premixed low NOx combustor has low NOx emission characteristics.

• Journal of the Korean earth science society
• /
• v.35 no.5
• /
• pp.313-323
• /
• 2014

We secured the high dispersion spectra of the symbiotic star CI Cyg. The HI, HeI, and HeII line profiles were analyzed using the relatively long exposure data including 1800 sec (Sep. 12, 1998, phase=0.90), 3600 sec (Aug. 12, 2002, ${\phi}=0.47$), and 1800 sec (Oct. 21, 2009, ${\phi}=0.54$). Although a minor outburst was reported in 2008, our three observation periods were generally known to be quiescent in earlier photometric studies. With the help of hydrodynamic simulations, we identified the two emission zones responsible for the blue- and red-shifted line components: (a) an accretion disk around a hot white dwarf star which consists of the outer cool HeI emission zone and the inner hot HeII emission part, and (b) a high density zone near the inner Lagrangian point responsible for the HeI line flux variation and the broadening of its line profile. The HeII line fluxes indicate that the HeII emission zone of the accretion disk is relatively stable, implying a constant gas inflow from the giant star throughout the quiescent period. The 2002 HeI data showed that the notable mass flow activity through the inner Lagrangian point occurred during this period and its flux intensity became strongest, whereas the HeII line width in the same period indicates that its flow activity forced the accretion disk to expand. The [OIII] lines were observed in 1998 but not detected in 2002 and 2009, implying the disappearance of the low density zone. Based on our kinematical studies upon the line profiles, we conclude that CI Cyg was stable in 1998 among the three observation periods selected in this research.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.30 no.3D
• /
• pp.247-254
• /
• 2010

The positive effects of the air quality improvement policy have revealed sufficiently such as 3.3 trillion won of social benefits under the Environmental Zone in five years(K. Choi, 2009). In case of low-income freight truck owner, however, could be burdened with the requirement likes emission decreasing equipment. Eventually, restraint of running in the Environmental Zone would be affected their livelihood seriously. After estimating the scale of low-income freight truck owner for three alternatives with Road Freight Transport Center data, this study calculates decreased VKT to estimate the scale of monetary loss. In the result, decreased income amount of low-income freight truck owner under the restricted running estimated 6.1 trillion won during 5 years, quite exceeding 3.3 trillion won of the positive benefits as improving air quality, which means the necessity of immediate countermeasure. In other words, even though the governmental policy aimed benefits for the majority, the result implies that the total monetary losses of the minority could be exceed against the positives, therefore analysis should be considered carefully before the policy becomes effective.

• 한국연소학회:학술대회논문집
• /
• 1999.10a
• /
• pp.201-207
• /
• 1999

The combustion characteristics for the low NOx 50 kW-class gas turbine combustor have been experimentally investigated. In order to achieve the premixing and the lean burn combustion, the geometries of the primary zone including premixed chamber were modified from conventional combustor. The centerline profiles of CO and NO concentration, and temperature were measured for the premixed combustors with or without dilution holes in the liner. The effects of the pilot fuel injection rate and air dilution on flame stabilization and pollutant (CO, NO) emission are discussed in detail.

• Journal of the Korean Society of Combustion
• /
• v.14 no.1
• /
• pp.19-24
• /
• 2009

A novel low NOx oil burner of 0.7 MW (for a 1 ton steam/hr industrial boiler) was designed and tested to investigate the combustion characteristics through in-flame measurement and flue gas analysis. Flame shape was observed by CCD camera and $CH^*/{C_2}^*$ radical distribution in the flame were observed, along with measurement of flue gas composition such as NOx and CO, for various heat inputs, excess airs and pressure of the fuel spary nozzles. The flame showed the two-zone structure: fuel-rich and fuel-lean zone, which was very favorable for the low-NOx combustion, and the NOx emission for haevy oil combustion was significantly reduced to < 150 ppm at 4 % $O_2$, compared with the NOx level of a conventional heavy oil burner.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.22 no.6
• /
• pp.196-207
• /
• 2023

As part of measures to address the climate crisis, buses are also being converted to electric and hydrogen buses. Local authorities need to prioritize carbon emissions when allocating newly introduced and converted electric and hydrogen buses, and as a method, consider the introduction of Low Emission Bus Zones (LEBZ) to propose the reduction of pollution from specific links. To introduce LEBZ, it is necessary to compare the carbon emissions before and after its implementation, yet there is a shortage of studies that focus solely on buses or analyze the effects of introducing LEBZ to specific links. In this paper, we utilized bus information system data to calculate and compare the effects of introducing LEBZ to bus priority lanes in Jeju. We categorized scenarios into five groups, with scenarios 1 through 4 involving the introduction of LEBZ, and scenario 5 designating cases where LEBZ was not introduced. Comparative results confirmed that in scenarios with LEBZ introduction, the reduction per km reached a maximum of 0.097t per km, whereas in cases without LEBZ, it amounted to 0.022t per km, demonstrating higher efficiency. It underscores the significance of conducting carbon emission calculations and comparing the effects of LEBZ introduction using bus information system data, which can be directly applied by local authorities to make informed and rational decisions.

• Journal of the Korean Society for Heat Treatment
• /
• v.14 no.4
• /
• pp.212-219
• /
• 2001

The fatigue test was carried out to evaluate the fatigue characteristics of fire resistance steel for frame structure and heat affected zone (HAZ) by the one side Gas Metal Arc Welding (GMAW). In this paper, the fatigue crack growth behavior was investigated with the compact tension specimen of base metal and the HAZ according to chemical composition and rolling end temperature, respectively. And the acoustic emission signals obtained from the fatigue test were analyzed by the time-frequency analysis method as a nondestructive evaluation. Main results obtained are summarized as follows; The hardness was appeared softening phenomenon that weld metal and HAZ are lower than that of base metal. Fatigue life of welded specimen was longer than that of base metal. m was 3~4.5 in base metal and 3.8~5.8 in HAZ. The main frequency range of acoustic emission signal analyzed from time-frequency method is different with the range by noise and crack. Also, it could be classified that it was also generated by fracture mechanics of dimple, inclusion etc.

• Journal of the Korean Society of Combustion
• /
• v.9 no.1
• /
• pp.11-17
• /
• 2004

The purposes of this study are to analyze nitrogen oxides(NOx) formation mechanism and to reduce abnormal NOx emissions in gas turbines. Industrial gas turbines emissions have potential to negative affect to the atmosphere in many different ways such as photochemical smog, acid rain and global warming. In conventional gas turbine combustors, one of the main pollutants such as nitrogen oxide(NOx) species, are principally formed from combustion process of fuel with oxygen in the primary combustion zone, and their emission levels are highly depend on peak temperatures in the combustor. In order to examine the characteristics and the effect of NOx formation, we used gas turbine of which commercial operating in Korea. From the examination, it has been found that NOx emissions are relatively high at low load(output) and during combustion mode change. Also, the effect of Air/Fuel ratio was considered. As the Air/Fuel ratio was increased in Lean-Lean mode, the NOx emission was decreased. The results of this study indicated that NOx emission levels are highly depend on peak temperature and pressure of combustion process in the combustor.

• Journal of Environmental Science International
• /
• v.11 no.6
• /
• pp.543-551
• /
• 2002

A Numerical simulation on the thermal flow performance was carried out to propose the incinerator type for the domestic refuses and to investigate the design factor and operating conditions. The SSTI(Standard Stoker Type Incinerator) proposed in this study was modified from the type with central f)ow. It has the characteristics of good mixing between refuse and hot combustion gas in primary combustion chamber and between unburned gas inflowing and secondary air jet in secondary chamber. By predictive results, the SSTI was no recirculation zone in secondary chamber so that mixing time was increased with high residence time. It has good characteristics of combustion and low emission. Parametric screening studies have been understood with phenomenon of combustion in incinerator.

• Journal of Korean Society for Atmospheric Environment
• /
• v.12 no.2
• /
• pp.131-139
• /
• 1996

The developent of ceramic combustor is being increased beca- use of the excellent physical properties of ceramic material, that is, high-resistant strength, high emissivity power and high corrosin-resistance. Ceramic combustor has been interested in the application of ultra-lean combustion for low NO$_{x}$ emission and gaseuos waste incineration with good combustion. This experimental study was conducted to investigate the combustion and emission characteristics of wall recess type ceramic combustor with equivalence ratio, mixture flow velocity and wall recess depth as parameters. The results in this study are as follows: 1. Wall recess played a important role to extend flame stability region. 2. The peak temperature of gas was peoportional to equivalence ratio, mixture flow velocity and wall recess depth. 3. The static pressure of mixing chamber and inlet temperature depended on the position of flame zone. 4. NO reduction was achieved by lean mixture without lower combustibility.y.