• Bulletin of the Korean Chemical Society
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• v.23 no.11
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• pp.1531-1540
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• 2002

With the invention of the inlaying technique for celadon in the latter half of the 12th century, the Koryo potters reached a new height of artistic and scientific achievement in ceramics chemical technology. Inlaid celadon shards, collected in 1991 during the surface investigation of Kangjin kilns found on the southwestern shore of South Korea, were imbedded in epoxy resin and polished for cross-section examination. Backscattered electron images were taken with an electron microprobe equipped with an energy dispersive spectrometer. The spectrometer was also used to determine the composition of micro-areas. Porcelain stone, weathered rock of quartz, mica, and feldspar composition were found to be the raw material for the body and important components in the glaze and white inlay. The close similarity between glaze and black inlay in the microstructure suggests that the glaze material was modified by adding clay with high iron content, such as biotite, for use as black inlay. The deep soft translucent quality of celadon glaze is brought about by its microstructure of bubbles, remnant and devitrified minerals, and the schlieren effect.

• Journal of Advanced Marine Engineering and Technology
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• v.10 no.3
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• pp.107-118
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• 1986

The presenet research attempts to examine the combustion characteristics and the structure of the flame in turbulent premixed flames and thus enhance the combustion performance that leads to the design of the effective combustion system (untilizing LNG). Following experimental investigations for several stabilized premixed flames were attempted to identify the interactive mechanism between flame structures and flow fields; Visualization by Schlieren method, measurement of flow velocity by LDV, detection of ion current by ion probe, measurement of fluctuating temperature by thermocouple having compensation circuit, average values with respect to time of fluctuating amount for flow velocity, temperature, ion current, etc., variable RMS values, PDFs, autocorrelation, crosscorrelation, spatial macroscale, power spectra, and velocity scale. Continuing the authors published studies whose flame dominated by coherent structures and the characteristics of combustion reaction for irregular three dimensional flame and stabilized flame by step were investigated with obtained experimental quantities. Results of this research are following : The most turbulent flames support the structure of a Wrinkled laminar flame or laminar flamelets. It also observed that combustion reaction is related to small tubulence microscales of the turbulent flow fields closly.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.2
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• pp.8-14
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• 2018

In the present work, a numerical study is carried out to observe the characteristics of the flow and particle behaviors in a supersonic double Venturi abrasive blasting nozzle. Schlieren flow visualization and Pitot pressure at the nozzle downstream are also carried out, and those measurement results are compared to the numerical ones for code validation. Open and closed secondary holes on the double Venturi nozzle surface are tested for various nozzle pressures, and the results are compared with the ones observed for other similar supersonic Laval nozzles.

• International Journal of Automotive Technology
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• v.2 no.3
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• pp.85-91
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• 2001

Characteristics of methane direct-injection spark-ignition stratified combustion in lean hydrogen mixture were analyzed both in a single cylinder engine and in a constant volume combustion chamber. Combustion pressure and Instantaneous combustion chamber wall temperature during the combustion process were measured with a thin-film thermocouple and used in analyses of combustion and cooling loss. Results in this research show that the premixed hydrogen increases cooling loss to combustion chamber wall while achieving combustion promotion, and the combustion system is effective especially in lean mixture conditions. Analysis of flame propagation was also done with Schlieren photography in the constant volume combustion chamber.

• International Journal of Automotive Technology
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• v.5 no.4
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• pp.239-245
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• 2004

It has been recognized that alternative fuels such as Liquid Petroleum Gas (LPG) show less polluting combustion characteristics than diesel fuel. Furthermore, engine performance is expected to be nearly equal to that of the diesel engine if direct-injection stratified-charge combustion of the LPG can be adopted in the spark-ignition engine. However, spray characteristics of LPG are quite different from those of diesel fuel. understanding the spray characteristics of LPG and evaporating processes are very important for developing efficient and low emission LPG engines optimized in fuel injection control and combustion processes. In this study, the LPG spray characteristics and evaporating processes were investigated using the Schlieren and Mie scattering optical system and single-hole injectors in a constant volume chamber. The results show that the mixture moves along the impingement wall that reproduced the piston bowl and reaches in ignition spark plug. LPG spray receives more influence of ambient pressure and temperature significantly than that of n-dodecane spray.

• Journal of Advanced Marine Engineering and Technology
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• v.13 no.4
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• pp.33-39
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• 1989

A turbulent premixed flames of layer formed between burned hot gas and unburned mixture were investigated by means of schlieren photograph with fluctuations of temperature and ion current. The combustion intensity between burned hot gas and shear layer was higher than the intensity between unburned mixture and shear layer. A wrinkled laminar flame and flamelet were appeared at downstream to exist and distributed reaction zone was at upstream as a result of analyzed probability density functions of temperature fluctuation. The initial combustion intensity of reaction zone of eddy between burned hot gas and shear layer was higher than that of final, flowing downstream, and vice versa between unburned mixture and shear layer.

• Applied Science and Convergence Technology
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• v.24 no.1
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• pp.16-21
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• 2015

The characteristics of an atmospheric pressure plasma jet (APPJ) in He discharge are measured with electrical and optical diagnostics methods. The discharge phenomenon in one cycle of the APPJ was diagnosed using intensified charge coupled device (ICCD) imaging. The gate mode images show that the propagation of plasma bullets happens only when the applied voltage on the inner conductor is positive. Moreover, the Schlieren image of the plasma jet shows that the laminar flow is changed into a turbulent flow when the plasma jet is turned on, especially when the gas flow rate increases.

• Journal of the korean Society of Automotive Engineers
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• v.15 no.6
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• pp.33-36
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• 1993

연소실 내의 화염 전파를 검출하는 대표적인 방법으로 High Schlieren Cinematography방식, 광섬유를 이용하는 방법, 이온화 현상을 이용하는 것 등이 있다. 광섬유를 이용하는 방법은 연소실 벽면에 광섬유를 적절히 배치하고 광섬유에서 나오는 신호를 전기적 신호로 바꾸어 해석하는 것이다. 연소시 화염에서 방출되는 빛을 연소실 벽에 적절하게 배치되어 있는 광섬유를 통하여 포토 다이오드로 전송된다. 포토 다이오드는 빛에너지를 전기 신호로 바꾸고, 이 아날로그 신호는 증폭된다. 전압 비교기는 증폭된 신호를 디지탈화하고, 이 신호가 PC에 저장된다. 이 방법은 연소실 벽이나 피스톤 등을 투명화하기 위한 구조변경이나 재질변화로 인한 엔진특성변화를 피할 수 있다. 본 연구에서는 광섬유를 이용하는 측정방법에 대해 연구하였다.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.3
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• pp.10-18
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• 2004

It is well known that the stratified charge combustion has many kind of advantages to combustion characteristics, such as higher thermal efficiency and less CO, NOx levels than conventional homogeneous mixture combustion. Although this combustion can be caused low fuel consumption, it is produced the high unburned hydrocarbon and soot levels because of different equivalence ratio in the combustion chamber. Moreover it has a lot of possibility of low output and misfire if the mixture gas would not be in existence around the spark plug. In this paper, fundamental studies for stratified combustion were carried out using a constant volume combustion chamber. The effect of locally mixture gas distribution according to control the direct injection and premixed injection in the chamber were examined experimentally. In addition, the effects of turbulence on stratified charge combustion process were observed by schlieren photography.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.1
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• pp.213-221
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• 1998

The investigation regarding the ignition system of a plasma jet explored by using a constant volume vessel. The purpose of this study is to elucidate relation between the characteristics of the configuration and jet ejection of plasma jet plug, when the sub energy were supplied at plasma jet ignition system. From the results of a visualization by the schlieren system, the jut ejection for plasma jet ignition are depended on the jet plug configuration and sub energy, but the configuration of plasma jet plug is more influenced than the sub energy on the plasma jet ejection. And the plasma jet ignition strongly influences upon the combustion enhancement than the conventional spark ignition.