• 한국연소학회:학술대회논문집
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• 대한연소학회 2003년도 제27회 KOSCO SYMPOSIUM 논문집
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• pp.83-88
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• 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.

• 한국지구과학회지
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• 제35권5호
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• pp.313-323
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• 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.

• 대한토목학회논문집
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• 제30권3D호
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• pp.247-254
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• 2010

수도권 도심 대기질 개선을 위한 환경지역 운영 정책의 긍정적 편익이 5년간 약 3조 3천억원인 것으로 추산(최기주, 2009)되는 등 해당 정책의 당위성은 충분히 인정되고 있다. 그러나 영세 화물 차주에게 배출저감장치 부착 등과 같은 저공해화 조치는 큰 부담이며, 저공해화 미이행 차량에 대한 환경지역의 운행규제는 생계에 치명적인 영향을 끼칠 수 있다. 본 연구에서는 화물운송시장 자료 등을 활용하여 3개 대안별 영세 화물 차주의 규모를 추정한 뒤, 교통수요분석을 통해 해당 차량의 총주행거리 감소분을 산정, 이에 따른 경제적 손실규모를 추정하였다. 그 결과 영세 화물 차주에 대한 손실규모 추정액은 5년간 약 6조 1천억원으로 긍정적 편익을 크게 상회하는 것으로 나타나 이에 대한 대응책 마련이 절실한 것으로 판명되었다. 이는 국가적인 차원에서 다수의 편익을 위해 추진하는 정책이라 할지라도 소수의 의한 경제적 손실규모가 더 크게 발생할 수 있기 때문에 정책 시행에 앞서 충분한 검토가 필요함을 시사한다.

• 한국연소학회:학술대회논문집
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• 한국연소학회 1999년도 제19회 KOSCO SYMPOSIUM 논문집
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• pp.201-207
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• 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.

• 한국연소학회지
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• 제14권1호
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• pp.19-24
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• 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.

• 한국ITS학회 논문지
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• 제22권6호
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• pp.196-207
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• 2023

기후위기 대응을 위한 대책으로 버스도 전기, 수소 버스로 우선 전환되고 있다. 지자체는 신규 투입, 전환되는 전기, 수소 버스 배정의 우선순위를 탄소배출량에 따라 판단할 필요가 있으며 그 방법으로 특정 구간에 무공해버스 운행만 허용하는 LEBZ 도입을 고려할 수 있다. LEBZ를 도입하기 위해서는 도입 전후 탄소배출량 절감 효과를 비교할 필요가 있으나 LEBZ도입 방안과 도입 시 효과를 분석하는 연구는 부족한 상황이다. 본 논문에서는 버스정보시스템 데이터를 활용하여 제주특별자치도를 대상으로 버스우선차로에 LEBZ 도입 시 효과를 산출하고 비교하였다. 분석 시나리오를 총 5개로 구분하여 시나리오1부터 4까지는 LEBZ 도입, 시나리오5는 LEBZ를 지정하지 않고 일부 차량만 전기, 수소 버스로 전환하는 경우로 구성하였고, 버스정보시스템 자료를 이용하여 탄소배출량을 비교한 결과 LEBZ를 도입한 경우가 km당 감축량이 최대 0.097t, 그렇지 않은 경우가 0.022t으로 LEBZ 도입은 높은 효율을 보임을 확인하였다. 본 논문은 제안한 버스정보시스템 데이터를 활용한 탄소배출량 산출 및 LEBZ 도입에 따른 효과 비교를 통해 각 지자체에서도 전기, 수소 버스 투입 시 의사 결정을 보다 합리적으로 할수 있는 방법론 제시에 의의를 두었다.

• 열처리공학회지
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• 제14권4호
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• pp.212-219
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• 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.

• 한국연소학회지
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• 제9권1호
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• pp.11-17
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• 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.

• 한국환경과학회지
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• 제11권6호
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• pp.543-551
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• 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.

• 한국대기환경학회지
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• 제12권2호
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• pp.131-139
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• 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.