• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2001년도 제17회 학술발표회 논문초록집
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• pp.55-60
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• 2001

Recently, there have been many research efforts to improve the fuel regression rate in the hybrid rocket engines. In the present study, the ongoing research and development of the next general ion hybrid rocket engine are systematically reviewed. The detailed discussions have been made for the innovative combust ion technologies including the vortex hybrid rocket engines , cryogenic sol id propellant hybrid rocket engine, and the gas generator hybrid rocket engines.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2015년도 제51회 KOSCO SYMPOSIUM 초록집
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• pp.115-116
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• 2015

In the present approach, the flame-acoustics interaction is represented by FDF (Flame Describing Function) which is a important source term in the Helmholtz' equation. In this study, the combustion instability is analyzed by the forced mode strategy with the measured FDF. Numerical results indicate that the present approach reasonably well predicts the essential features of the combustion instability characteristics in the lean premixed combustor under the gas-turbine like environment.

• 한국연소학회:학술대회논문집
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• 한국연소학회 제26회 KOSCO SYMPOSIUM 논문집
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• pp.191-194
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• 2003

The present study is focused on the subgrid scale combustion model in context with a Large Eddy Simulation. In order to deal with detailed chemical kinetic, the level-set method based on a flamelet model is addressed. In this model, the flame front is treated as an interface, represented by an iso-surface of a scalar field G. This iso-surface is convected by the velocity field and its filtered quantities are include the turbulent burning velocity, which is to be modelled. For modelling the turbulent burning velocity, an equation for the length-scale of the sub-filter flame front fluctuations was developed. The formulations and issues for the turbulent premixed and partially premixed flames are addressed in detail.

• 한국연소학회:학술대회논문집
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• 한국연소학회 제26회 KOSCO SYMPOSIUM 논문집
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• pp.215-222
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• 2003

Mild combustion or Flameless oxidation(FLOX) have been considered as one of the most prospective clean-combustion technologies to meet both the targets of high process efficiency and low pollutant emissions. A mild combustor with high air preheating and strong internal exhaust gas recirculation is characterized by relatively low flame temperature, low NOx emissions, no visible flame and no sound. In this study, the Steady Flamelet Approach has been applied to numerically analyze the combustion processes and NOx formation in the mild combustor. The detailed discussion has been made for the basic characteristics of mild combustor, numerical results and limitation of the present combustion modeling.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2006년도 제33회 KOSCO SYMPOSIUM 논문집
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• pp.97-103
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• 2006

This work forcus on the development of gas sensor that measure the concentrations of exhaust gas using diode laser. Each diode laser for exhaust gas measurement is set to work at near-IR using both DA and WMS methods. Also use of fiber-coupled optical elements makes such a sensor rugged and easy to align. On-line data acquisition and processing can be performed with a PC running LabVIEW software, and absorption signals are measured simultaneously by multiplexing method. Finally, It were experimentally compared WMS (Wavelength Modulation Spectroscopy) with DA (Direct Absorption) for the accuracy.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2006년도 제33회 KOSCO SYMPOSIUM 논문집
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• pp.53-59
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• 2006

This study is measurement of radicals in gas & light oil diffusion flame focused on burner exit. The goal of this study is to analyse the relationship between flame chemiluminescence($OH^{\ast}$, $CH^{\ast}$, $C_2^{\ast}$) intensities and flame conditions. The investigation performed turbulent diffusion flame of commercial burner in varying the excess air ratio from 1.0 to 1.8. The optical emissions were measured by photomultiplier(PMT) using optical band pass filter and spectrometer system. The effects of excess air ratio and NOx emission characteristics on the radical emission intensities were investigated experimentally.

• 한국자동차공학회논문집
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• 제13권3호
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• pp.74-79
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• 2005

The Homogeneous Charge Compression Ignition(HCCI) combustion is currently under intensive investigation because of its potential to increase thermal efficiency while greatly decreasing NOx and p.M. In order to account for the thermal boundary layer effects, the two-zone model has been developed to analyze the combustion characteristics of HCCI engine. The detailed chemistry are represented by the GRI mechanism 3.0 involving 53 species and 325reactions. The present combustion model has been validated against the experimental results. Computations are also made for the wide-range operating conditions of HCCI engine.

• 보건의료산업학회지
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• 제9권3호
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• pp.57-67
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• 2015

Objectives : This study has analyzed the relationship between DEA efficiency of costs-patient revenues, productivity per value added and management performance in mental hospitals. Methods : The relationship between DEA efficiency of costs-patient revenues, the productivity per value added and management performance were conducted with correlation analysis and logistic regression. Results : The DEA efficiency of costs-patient revenues had a significant causal relationship with the value added ratio to gross revenue indexing productivity per value added. On the other hand, it was revealed that the operating margin indexing management performance had a slightly significant causal relation with DEA efficiency of costs-patient revenues. Conclusions : The material costs should be focused on the management stability of mental hospitals, and known to the desirable management orientation for the higher efficiency of costs-patient revenues.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2014년도 제49회 KOSCO SYMPOSIUM 초록집
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• pp.133-134
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• 2014

The full transport equation approach for laminar non-premixed flame with detailed chemistry, soot and radiation has an advantage in accuracy and describing for emission pathway, but this approach requires the excessive computational cost especially for a higher-order hydrocarbon fuel flames. On the other hand, the standard flamelet model has an efficiency and accuracy for non-premixed flame, though this model is not suitable for simulating slow processor like soot and radiation in laminar non-premixed flame situation. To overcome this limitation, modified transient flamelet model is developed which coupled with two-equation soot model involved in soot formation and evolution mechanism such as nucleation, surface growth, oxidation and agglomeration.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2014년도 제49회 KOSCO SYMPOSIUM 초록집
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• pp.75-76
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• 2014

The present study has numerically investigated the effects of the oxidizer-side nitrogen dilution on the precise structure and NOx formation characteristics of the turbulent syngas nonpremixed flames. Eulerian particle flamelet model was used to predicted the NOx formation characteristics in the turbulent syngas swirling nonpremixed flames. Current numerical simulation was conducted for the syngas gas turbine combustor. Numericla results indicate that as the H2O portion is increased in diluent, the formation of NOx decreased effectively in turbulent syngas swirl nonpremixed flames.