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李大喆 전북대학교 공업기술연구소 1985 工學硏究 Vol.16 No.-
In the manufacturing process for obtaining reduced iron from pickling-oxide with the charged carbon, the production of reduced iron in controlled by the prereduction process of the charged carbon-oxide pellet by carbon. consequently, for the increase of this product, the basic knowledge of the reduction mechanism packed pellet has to be reviewed. In this paper, time dependences of fractional reduction for a pellet at 800℃-1,100℃ were measured for charged carbon-oxide pellet with 2.25%, 4.5% charged carbon and added reducing agent BaCO_3(1-55), using reducing agent carbon. Fraction reduction is measured for ratio outer diameter of unreacted part and that of reduced iron.
李大澈,李宗석 大田工業大學 1992 한밭대학교 논문집 Vol.9 No.1
A analyticl model is used to study the deformation of meandering river patterns from an initial sine-generated state. The time required for the development of neck cutoff condition is shown to depend on the meander wavelength and on the initial meander amplitude. Sinuosity affects the downvalley migration speed, the amplitud, and the minmum radius of channel curvature of a meander waveform. The wavelength influnces the behavior of a meander pattern as it migrates toward an inerodible boundary and also as it interacts with a straight channel.
李大澈 大田工業高等專門學校 1971 論文集 Vol.8 No.-
The formulars for the bearing power of pile are to be classified from the standpoints of both dynamics and statics, This paper is to get the values of repulsive coefficient and effective one by investigating and analyzing the actions and reactions of pile, drop hammar and soil. The resluts are as follows: 1. The value of 'e' repulsive coefficient is, In the natural earthy stratum : 0.15-0.2 In the natural silt stratum : 0.1-0.13 In the natural clay stratum: 0.08-0.1. 2. The value of 'L', effective coefficient must be amended. 3. The drop hammar is thoough to be driven into with pile, but in fact it repulses, and only pile is driven into with the given speed, 4. Soil pressure is in proportion to the certain depth of pile, but the soil pressure around column capital is proved to diminish. 5. The soil pressure, pressure distribution, and Poisson's ratio in column capital are to be amended.
李大喆 全北大學校 1989 論文集 Vol.31 No.-
The corrosion resistance of titanium is improved by formation of passive film. In this study, therefore, in order to investigate the formation procedure of titanium oxide film by thermal oxidation, titanium plate with purified oxygen gas has been reacted in a temperature between 300℃ and 600℃. And the analysis of titanim oxide film has been investigated by X-ray diffractometer, SEM (Scanning Electron Microscope) and gravimetric method. The corrosion of the thermally formed oxide film on titanium has been studied in HCI, H_2SO_4 and HNO_3 solution. The experimental results are as follows ; 1. Titanium oxide obtained in a temperature between 350℃ and 600℃ appeared better protection than preheat treatment in all acidic solution. 2. TiO_2, the stable phase of tianium oxide, was formed at 400℃ and uniformly formed at 550℃. The result was that corrosion resistance increased. 3. Over the 600℃, the oxide film was unstable and corrosion resistance in proportion to incerease heat treatment time and temperature. 4. As oxide film formed, corrosion resistance increased in heterogeneous state but decreased in over stable stage.
李大喆,李圭澤 全北大學校 1979 論文集 Vol.21 No.-
In the manufacturing process for obtaining reduced sponge iron from pickling-oxide, the production of sponge iron is strictly controlled by pre-reduction process of the pickling oxide bed by coal coke and anthracite. Consequently for the increased of this product, the fundamental knowleadge of a reduction mechanism of the packed bed has to be reviewed. In this study, time dependences of fractional reduction R for a packed columnar iron oxide bed at 1100℃ were measured for various kind of iron oxides with various particle size, using reducing agents, coal coke and anthracite. Fractional reduction R is measured for ratio of outer diameter of unreacted part r_0 and that of sponge iron r, R=1-(r r_0)^2.
李大澈,이종석,金二顯 大田産業大學校 1996 한밭대학교 논문집 Vol.13 No.1
This study is in comparison the theoretical calculated values by the critical channel slope method with the field measured data in a braided channel. A consequence by the dimensional analysis showed to 3 dimensionless variable quantities one of the 6 variables, tractive force, particle size, water and sediment density, gravity acceleration and dynamic viscosity, related to transport of sediment particles. As a study channel reach we chose a small part of MIHO river which is a well developed braided channel in tributary of the KUM river catchment area, and it divided into 25 sections to the channel reaches 4,680m. Theoretical critical channel slope appeared at the section No. 21 and the meandering channel from began to appear instead of braided form at near section No.23 downstream about 320m from section No.21. And also the critical channel slope was 1/1,591 in theory but in field it is 1/1,613.