• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.10a
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• pp.157-158
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• 2009

• Journal of Environmental Health Sciences
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• v.25 no.3
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• pp.108-112
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• 1999

A study was conducted for the effects of input energy on fume formation ratios based on electrode(FFR$_{electrode}(g/kg_{electrode})),\;deposited\;metal(FFR_{weld}(g/kg_{weld}))\;and\;slag(FFR_{slag}(g/kg_{slag}))\;at\;CO_2$ flux cored arc welding on stainless steel. Experiments were run in well designed welding fume box. Six types of flux cored wires were used and three levels of current and voltages were given. The measured values of $FFR_{electrode},\;FFR_{weld},\;FFR_{slag}\;are\;7.90{\pm}1.47\;g/kg_{electrode},\;9.18{\pm}1.65\;g/kg_{\electrode},\;71.8{\pm}24.2\;g/kg_{slag}$ respectively. Fume formation ratios are not increased dramatically by input energy because of simultaneous increasing of melted electrodes, deposited metal and slag. The results indicate that the test of fume formation ratios in the research on production of low fume welding wire can be run at the fixed condition of input energy rather than various condition.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.193-198
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• 2010

In solid propellant rocket motors, $Al_2O_3$, one of combustion products, can be accumulated inside a combustion chamber. A special rocket motor was designed and tested to simulate thermal reaction of rubber insulator affected by the deposited slag. We successfully demonstrated through a dynamic radioscopy that the slag was deposited at the location as designed. In this paper we present a new test method which can simulate a high temperature and pressure environment in combustion chamber to evaluate material characteristics of rubber insulator and can provide design data to decide its thickness for a new solid rocket motor. The solid rocket motor, which has an average chamber pressure of 770 psia and a burning time of 50 seconds, was tested. The results show that erosion of EPDM insulator is more affected by a gas velocity rather than by the thermal reaction of slag with a high thermal capacity.

• Journal of the Korean Society of Propulsion Engineers
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• v.15 no.3
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• pp.9-14
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• 2011

In solid propellant rocket motors, $Al_2O_3$, one of combustion products, can be accumulated inside a combustion chamber. A special rocket motor was designed and tested to simulate thermal reaction of rubber insulator affected by the deposited slag. We successfully demonstrated through a dynamic radioscopy that the slag was deposited at the location as designed. In this paper we present a new test method which can simulate a high temperature and pressure environment in combustion chamber to evaluate material characteristics of rubber insulator and can provide design data to decide its thickness for a new solid rocket motor. The solid rocket motor, which has an average chamber pressure of 770 psia and a burning time of 50 seconds, was tested. The results show that erosion of EPDM insulator is more affected by a gas velocity rather than by the thermal reaction of slag with a high thermal capacity.

• 한국연소학회:학술대회논문집
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• 2013.06a
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• pp.65-68
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• 2013

In a syngas cooling system of coal gasification process, fly slag carried by syngas deposit on the surface of heat exchanger. The deposited materials form a fouling layer with several millimeters thickness, disturbing heat transfer between steam and syngas. This study investigates flow and heat transfer characteristics of syngas in helical coil heat exchanger using computational fluid dynamics under clean and fouled surface condition. Process model were also designed and its results are in good agreement with CFD results.

• Proceedings of the KWS Conference
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• 2010.05a
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• pp.51-51
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• 2010

Recently just as in the automobile industry, shipbuilders also try to reduce material consumption and weight in order to keep operating costs as low as possible and improve the speed of production. Naturally industry is ever searching for welding techniques offering higher power, higher productivity and a better quality. Therefore it is important to have a details research based on the various welding process applied to steel and other materials, and to have the ability both to counsel interested companies and to evaluate the feasibility of implementation of this process. Submerged-arc welding (SAW) process is usually used about 20% of shipbuilding. Similar to gas metal arc welding(GMAW), SAW involves formation of an arc between a continuously-fed bare wire electrode and the work-piece. The process uses a flux to generate protective gases and slag, and to add alloying elements to the weld pool and a shielding gas is not required. Prior to welding, a thin layer of flux powder is placed on the work-piece surface. The arc moves along the joint line and as it does so, excess flux is recycled via a hopper. Remaining fused slag layers can be easily removed after welding. As the arc is completely covered by the flux layer, heat loss is extremely low. This produces a thermal efficiency as high as 60% (compared with 25% for manual metal arc). SAW process offers many advantages compared to conventional CO2 welding process. The main advantages of SAW are higher welding speed, facility of workers, less deformation and better than bead shape & strength of welded joint because there is no visible arc light, welding is spatter-free, fully-mechanized or automatic process, high travel speed, and depth of penetration and chemical composition of the deposited weld metal. However it is difficult to application of thin plate according to high heat input. So this paper has been focused on application of the field according to SAW process for thin plate in ship-structures. For this purpose, It has been decided to optimized welding condition by experiments, relationship between welding parameters and bead shapes, mechanical test such as tensile and bending. Also finite element(FE) based numerical comparison of thermal history and welding residual stress in A-grade 3.2 thickness steel of SAW been made in this study. From the result of this study, It makes substantial saving of time and manufacturing cost and raises the quality of product.

• Journal of the Korea Concrete Institute
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• v.20 no.5
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• pp.619-626
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• 2008

There have been numerous studies to develop eco-friendly concrete. The attempt to reduce the amount of cement usage is suggested as one of the solutions for eco-friendly concrete. To reduce the amount of cement usage, the pozzolan-reaction materials such as ground granulated blast furnace slag, fly ash, and meta kaolin are widely used as the mineral admixture. Hwangtoh which deposited broadly in Korea is a well known eco-friendly material and the activated Hwangtoh with pozzolan-reaction can be practically used as a mineral admixture of concrete. Meanwhile, PET fiber made of recycled PET bottle is a type of recycled material, which can be used to control micro cracks in concrete. But the study about concrete mixed with recycled PET fiber is insufficient and the research of Hwangtoh concrete mixed with PET fiber is urgently needed presently. In this study, experiment and analysis flexural behavior of Hwangtoh concrete blended with recycled PET fiber are carried out. The results are discussed in detail.