• Communications of the Korean Mathematical Society
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• v.10 no.2
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• pp.317-323
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• 1995

In this note we prove that Apostol's conjecture is true for the operators having totally disconnected spectra and also give a result related on compalence.

• Journal of IKEEE
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• v.17 no.4
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• pp.559-563
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• 2013

This paper analytically proves the equivalence between two main oscillator phase noise theories, which are based on the ISF, and Floquet vector, respectively. For this purpose, this study obtains the power spectral density matrix from the ISF-based phase noise theory. As a result, one can prove that the power spectral density matrix obtained from the ISF-based phase noise theory is essentially equivalent to the power spectral density matrix presented by the Floquet vector-based phase noise theory, which manifests the equivalence of the two main theories. This study is intended to provide deeper insight into the relations between the two main theories.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.33 no.3
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• pp.218-225
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• 1997

The formerly proposed spectral model of turbulent burning velocity is refined for nonstoichiometric hydrocarbon mixtures. Refinements are made in regard to the following two points : (1) an effect of the diffusivity of deficient reactant on the turbulent burning velocity and (2) consideration of increasing laminar name thickness with a decrease in the laminar burning velocity A comparison between the predicted turbulent velocities and the measured ones is made. The predictions by the refined spectral model agree quantatively well with the experimental results in the regime of practical equivalence ratio, but not in the high and low equivalence ratio regime.

• YAKHAK HOEJI
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• v.39 no.2
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• pp.205-209
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• 1995

Methylene protons of benzyl and ethyl ester in ethyl 1-benzyl-2, 3-dioxo-cyclopenta[b]-pyrrole-3a-carboxylate (A) exhibited opposite$^{1}$H-NMR spectral patterns mutually between magnetic equivalence and nonequivalence depending on concentration and temperature. The diastereotopic spectral data of compound A were reported with brief interpretation.

• 한국연소학회:학술대회논문집
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• 2015.12a
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• pp.233-235
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• 2015

This study is to investigate the combustion instability of the variation of combustion chamber length in dual swirl gas turbine model combustor. When equivalence ratio was fixed at 1.1, as the length of the combustion chamber increases the value of the frequency decreased in 7kW while the value of the frequency was constant in 4kW. The analysis of flame behaviors by high speed camera was conducted to identify such trend.

• 한국연소학회:학술대회논문집
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• 2006.04a
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• pp.19-25
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• 2006

Energy efficient and low pollution combustion systems the use gaseous fuels have been in great demand in recent year. Radiant burner in many different forms are emerging as very desirable combustion systems for same reason. Porous radiant burners are used in drying, preheating and curing, and in other type of materials processing and manufacturing processes. However, little knowledge is available about the operating characteristics and the structure of flames in porous ceramic fiber radiant burners. The objective of the present work is to investigate the global performance characteristics of the ceramic fiber burner. A detailed study which includes the spectral intensity, gas temperature, radiation efficiency and global pollutant emissions. Another objective is to study the flame structure of the ceramic fiber burner by measuring the local gas temperature. The results indicate that ceramic fiber burner do offer a 19-44% gain in radiant efficiency. The ceramic fiber burner exhibit significant spectral intensity peaks in the band at $2.0-2.5{\mu}m$. The local temperature distribution inside the mat and near the mat surface as a function of the equivalence ratio can be reasonably interpreted by the relation of the heat balance in the mat and movement of the reaction zone. Nox emission from ceramic fiber burner is less than 25ppm throughout the operating range.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.12
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• pp.35-40
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• 2006

The combustion instability in a model dump combustor with an exhaust nozzle and the possibility of combustion control using a loudspeaker to these instabilities were studied. By changing inlet velocity, combustor length and equivalence ratio, dynamic pressure signals and flame structures were simultaneously taken. Because inlet velocity and combustor length affect the life time of vortex in the dump combustor, the results showed that as the combustor length increased and the inlet velocity decreased, the instability frequency decreased and the maximum power spectral density of the dynamic pressure generally decreased. Also, instability frequency and maximum power spectral density of the dynamic pressure increased with the increment of equivalence ratio. From the data of close-loop control, the optimum time-delay control using a loudspeaker was confirmed to be able to reduce the vortex shedding induced from the mixed acoustic-convective mode combustion instability.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2005.11a
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• pp.445-449
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• 2005

The mixed acoustic-convective mode combustion instability and the possibility of combustion control using a loudspeaker to these instabilities were studied. By changing inlet velocity, combustor length and equivalence ratio, the dynamic pressure signals and the flame structures were simultaneously taken. The results showed that as the combustor length increased and the inlet velocity decreased, the instability frequency decreased and the maximum power spectral densities of the dynamic pressures generally decreased. The instability frequency could be affected by an equivalence ratio over the operating conditions. From the data of close-loop control, as the loudspeaker may work out-of-phase with the natural instability, the optimum time-delay controller was confirmed to be able to reduce the vortex shedding from the mixed acoustic-convective mode combustion instability.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.4
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• pp.600-609
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• 2001

WSGGM based low-resolution spectral model for calculating radiation transfer in combustion gases is applied to estimate self-absorption of radiation energy in one-dimensional opposed flow flames. Development of such a model is necessary in order to enable detailed chemistry-radiation interaction calculations including self-absorption. Database of band model parameters which can be applied to various one-dimensional opposed flow diffusion and partially premixed flames is created. For the validation of the model and database, low resolution spectral intensities at fuel exit side are calculated and compared with the results of a narrow band model with those based on the Curtis-Godson approximation. Good agreements have been found between them. The resulting radiation model is coupled to the OPPDIF code to calculate the self-absorption of radiant energy and compared with the results of an optically thin calculation and the results of a discrete ordinates method in conjunction with the statistical narrow band model. Significant self-absorption of radiation is found for the flames considered here particularly for the fuel side of the reacting zone. However, the self-absorption does not have significant effects on the flame structure in this case. Even in the case of the low velocity diffusion flame and the partially premixed flame of low equivalence ratio, the effects of self-absorption of radiation on the flame temperature and production of minor species are not significant.

• Journal of Plant Biotechnology
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• v.42 no.3
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• pp.257-264
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• 2015

To determine whether metabolite fingerprinting for whole cell extracts based on Fourier transform infrared (FT-IR) spectroscopy can be used to discriminate and compare metabolic equivalence, standard medicinal parts from four medicinal plants (Cynanchum wilfordii Hemsley, Atractylodes japonica Koidz, Polygonum multiflorum Thunberg and Astragalus membranaceus Bunge) and their in vitro-produced adventitious roots were analyzed by FT-IR spectroscopy. The principal component analysis (PCA) and partial least square discriminant analysis (PLS-DA) from the FT-IR spectral data showed that the whole metabolic pattern from Cynanchum wilfordii was highly similar to Astragalus membranaceus. However, Atractylodes japonica and Polygonum multiflorum showed significantly different metabolic patterns. Furthermore, adventitious roots from Cynanchum wilfordii and Astragalus membranaceus also showed similar metabolic patterns compared to their standard medicinal parts. These results clearly show that mass proliferation of adventitious roots may be applied to aquire novel supply of standard medicinal parts from medicinal plants. However, the whole metabolic pattern from adventitious roots of Atractylodes japonica and Polygonum multiflorum were not similar to their standard medicinal parts. Furthermore, FT-IR spectroscopy combined with multivariate analyses established in this study may be applied as an alternative tool to discriminate the whole metabolic equivalence from several standard medicinal parts. Thus, we suggest that these metabolic discrimination systems may be applied for metabolic standardization of herbal medicinal resources.