• Journal of ILASS-Korea
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• v.10 no.2
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• pp.1-9
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• 2005

An experimental study was carried out to obtain the fundamental data about the effects of radical ignition on premixture combustion. A CVC(constant volume combustor) divided into the sub-chamber and the main chamber was used. Numerous narrow passage holes are arranged between the main chamber and the sub-chamber. The products including radicals generated by spark ignition in tile sub-chamber derives the simultaneous multi-point ignition in the main chamber. We have examined the effects of the sub-chamber volume, the diameter and number of passage holes, and the equivalence $ratio({\Phi})$ on the combustion characteristics by means of burning pressure measurement and flame visualization. In a CVC, the overall burning time including the ignition delay became very short and the maximum burning pressure was slightly increased by the radical ignition(RI) method in comparison with those by the conventional spark ignition(SI) method. Combustible lean limit by RI method is extended by ${\Phi}=0.25$ compared with that by SI method. Also, In cases of charging the number and the diameter for the fixed total cross section of the passage holes, combustion period increased significantly at a sub-chamber with a single hole, but those of the other conditions had almost a similar tendency in the sub-chamber with 4 or more holes. regardless of equivalence ratio. Therefore, it was Proved that a critical cross section exists with the number of passage holes.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.75-78
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• 2004

Various jet engines (Turbine engine family and RAM Jet engine) have been developed for high speed aircrafts. but their application to hypersonic flight is restricted by principle problems such as increase of total pressure loss and thermal stress. Therefore, the development of next generation propulsion system for hypersonic aircraft is a very important subject in the aerospace engineering field, SCRAM Jet engine based on a key technology, Supersonic Combustion. is supposed as the best choice for the hypersonic flight. Since Supersonic Combustion requires both rapid ignition and stable flame holding within supersonic air stream, much attention have to be given on the mixing state between air stream and fuel flow. However. the wider diffusion of fuel is expected with less total pressure loss in the supersonic air stream. So. in this study the direction of fuel injection is inclined 30 degree to downstream and the total pressure of jet is controlled for lower penetration height than thickness of boundary layer. Under these flow configuration both streams, fuel and supersonic air stream, would not mix enough. To spread fuel wider into supersonic air an aerodynamic force, baroclinic torque, is adopted. Baroclinic torque is generated by a spatial misalignment between pressure gradient (shock wave plane) and density gradient (mixing layer). A wedge is installed in downstream of injector orifice to induce an oblique shock. The schlieren optical visualization from side transparent wall and the total pressure measurement at exit cross section of combustor estimate how mixing is enhanced by the incidence of shock wave into supersonic boundary layer composed by fuel and air. In this study non-combustionable helium gas is injected with total pressure 0.66㎫ instead of flammable fuel to clarify mixing process. Mach number 1.8. total pressure O.5㎫, total temperature 288K are set up for supersonic air stream.

• Korean Journal of Heritage: History & Science
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• v.54 no.4
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• pp.152-173
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• 2021

The Large Banner was introduced during the Japanese Invasions of Korea with a new military system. It was a flag that controlled the movement of soldiers in military training. In addition, it was used in other ways, such as a symbol when receiving a king in a military camp, a flag raised on the front of a royal procession, at the reception and dispatch of envoys, and at a local official's procession. The Large Banner was recognized as a symbol of military dignity and training rites. The Large Banner was analyzed in the present study in the context of two different types of decorations. Type I includes chungdogi, gakgi and moongi. Type II includes grand, medium, and small obangi, geumgogi and pyomigi. Each type is decorated differently for each purpose. The size of the flag is estimated to be a square of over 4 ja long in length. Flame edges were attached to one side and run up and down The Large Banner used the Five Direction Colors based on the traditional principles of Yin-Yang and Five Elements. The pattern of the Large Banner is largely distinguished by four. The pattern of large obangi consists of divine beasts symbolizing the Five Directions and a Taoism amulet letter. The pattern of medium obangi features spiritual generals that escort the Five Directions. The pattern of small obangi has the Eight Trigrams. The pattern of moongi consists of a tiger with wings that keeps a tight watch on the army's doors. As for historical sources of coloring for Large Banner production, the color-written copy named Gije, from the collection of the Osaka Prefect Library, was confirmed as the style of the Yongho Camp in the mid to late 18th century, and it was also used for this essay and visualization work. We used Cloud-patterned Satin Damask as the background material for Large Banner production, to reveal the dignity of the military. The size of the 4 ja flag was determined to be 170 cm long and 145 cm wide, and the 5 ja flag was 200 cm long and 175 cm wide. The conversion formula used for this work was Youngjochuck (1 ja =30cm). In addition, the order of hierarchy in the Flag of the King was discovered within all flags of the late Joseon Dynasty. In the above historical study, the two types of Large Banner were visualized. The visualization considered the size of the flag, the decoration of the flagpole, and the patterns described in this essay to restore them to their original shape laid out the 18th century relics on the background. By presenting color, size, material patterns, and auxiliary items together, it was possible not only to produce 3D content, but also to produce real products.