• 유체기계공업학회:학술대회논문집
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• 2000.12a
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• pp.312-317
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• 2000

High efficient steam turbine stage has been developed with the help of the 3-dimensional design tool. In this stage design, the compound leaned stacking method has been adopted to reduce the secondary flow loss of a turbine passage and to increase the performance efficiency for the turbine nozzles. And the turbine buckets have been designed with the quasi-3-dimensional turbomachinery blade design method. To verify the stage design, therefore, the 3-dimensional numerical simulation of a steam turbine stage was conducted. In this design, CFX-TASCflow was employed to predict the turbulent flow of a steam turbine stage. The analysis was performed in parallel calculation using the HP N4000 8 CPUs machine. The result showed CFX-TASCflow could be used as the 3-dimensional flow analysis tool of steam turbine design.

• Tribology and Lubricants
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• v.16 no.5
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• pp.389-394
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• 2000

Scanning Probe Microscope (SPM) such as Scanning Tunneling Microscope (STM) and Atomic Force Microscope (AEM) was shown to be the powerful tool for nano-scale characterization of material surfaces. Using this technique, surface morphology of the cyclically deformed Cu or Cu-Al single crystal was observed. The surface became proportionately rough as the number of cycles increased, but after some number of cycles no further change was observed. Slip steps with the heights of 100 to 200 nm and the widths of 1000 to 2000 nm were prevailing at the stage. The slipped distance of one slip system at the surface was not uniform, and formation of the extrusions or intrusions was assumed to occur such place. By comparing the morphological change caused by crystallographic orientation, strain amplitude, number of cycles or stacking fault energy, some interesting results which help to clarify the basic mechanism of fatigue damage were obtained. Furthermore, applicability of the scanning tunneling microscopy to fatigue damage is discussed.

• Carbon letters
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• v.2 no.1
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• pp.22-26
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• 2001

Na alloyed graphite intercalation compounds with stage 1 and 2 were synthesized using the high temperature and pressure technique. Thermal stability and staging transitions of the compounds were investigated depending on heating rates. The thermal stability and temperature dependence of the deintercalation compounds were characterized using differential scanning calorimeter (DSC) analyzer. Enthalpy of formations were confirmed at temperatures between 25 and $500^{\circ}C$, depending on the various heating rates. The structure ions and interlayer spaces of the graphite were identified by X-ray diffraction (XRD). Diffractograms of stages with non-integral (00l) values were obtained in the thermal decomposition process, and stacking disorder defects and random stage modes were observed. The average value of the interlayer C-C bond lengths were found approximately $2.12{\AA}$ and $1.23{\AA}$ from the diffractions. Based on the stage transition, the degree of the deintercalaton has a inverse-linear relationship against the heating rate.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.2
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• pp.143-150
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• 2015

At present, the actual condition is that Korean modular structures are limited to a low rise detached house and military barracks. And there is no standardized structural design method of stacked modular structure. Accordingly, in general, they don't review impact force in the stage of stacking and installing a module, the effect which wind load has on a structure in the stage of lifting, and inertial force occurring in the stage of lifting or transporting a module in the process of constructing a structure. Therefore, this study investigated the construction method of modular system to be studied in stages, and decided on the position to which load was applied and boundary condition in structural analysis at each construction stage. Besides, inertial force according to each speed was calculated in the lifting and wheeled transport of module. And we calculated impact load according to lifting speed in module stacking and installation work and wind load due to instantaneous wind speed in the installation work by lifting. On the basis of the suggested method, in the modular system to be studied, it carried out review of structure by changing determining conditions of load being applied by construction stage, such as in the stage of lifting, in the stage of transport, and in the stage of installation, and drew construction conditions securing stability structurally.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1999.06a
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• pp.67-72
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• 1999

Scanning probe Microscope(SPM) such as Scanning Tunneling Microscope(STM) and Atomic Force Microscope(AFM) was shown to be the powerful tool for nano-scale characterization of material surfaces Using this technique, surface morphology of the cyclically deformed Cu or Cu-Al single crystal was observed. The surface became proportionately rough as the number of cycles increased, but after some number of cycles no further change was observed. Slip steps with the heights of 100 to 200 nm and the widths of 1000 to 2000 nm were prevailing at the stage. The slipped distance of one slip system at the surface was not uniform. and formation of the extrusions or intrusions was assumed to occur such place. By comparing the morphological change caused by crystallographic orientation, strain amplitude, number of cycles or stacking fault energy, some interesting results which help to clarify the basic mechanism of fatigue damage were obtained. Furthermore, applicability of the scanning tunneling microscopy to fatigue damage is discussed.

• Journal of Internet Computing and Services
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• v.25 no.2
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• pp.21-28
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• 2024

Radar is an essential sensor component in autonomous vehicles, and the market for radar applications in this context is steadily expanding with a growing variety of products. In this study, we aimed to enhance the stability and performance of radar systems by developing and evaluating a radar performance prediction model that can predict radar defects. We selected seven machine learning and deep learning algorithms and trained the model with a total of 49 input data types. Ultimately, when we employed an ensemble of 17 models, it exhibited the highest performance. We anticipate that these research findings will assist in predicting product defects at the production stage, thereby maximizing production yield and minimizing the costs associated with defective products.

• The KSFM Journal of Fluid Machinery
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• v.17 no.5
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• pp.78-82
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• 2014

This paper describes a brief aerodynamic design procedure of multi-stage axial turbine. The design procedure was established including one dimensional scratch design, through flow analysis with empirical correlations, two dimensional airfoil design and three dimensional airfoil stacking. Detailed aerodynamic performance assessment was done with full three dimensional CFD method at the design and off design conditions to construct turbine performance map. With the present method, aerodynamic design procedure of 1st and 2nd stages of high pressure turbine for 10,000lbf class turbofan engine was introduced.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.275-278
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• 2005

The dynamic characteristics of rotor shafts for electric motors were investigated through the modal tests. The natural frequencies and modal dampings in each manufacturing stage of rotor core assembly were analyzed from the frequency response functions fer all 6 motors of a product model. The deviation of the each individual modal feature was found dependent on the mode shapes as well as the rotor assembly stage. The core stacking itself is known to widen the deviation of modal properties but fellowing processes of rotor bar insertion and swaging are confirmed to reduce the deviation. Finally the equivalent diameter of core part was estimated from the comparison of measured and calculated results to include the stiffness of core part.

• Journal of Intelligence and Information Systems
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• v.14 no.4
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• pp.31-46
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• 2008

A stacking yard of a container terminal is a space for temporarily storing the containers that are carried in or imported until they are carried out or exported. If the containers are stacked in an inappropriate way, the efficiency of operation at the time of loading decreases significantly due to the rehandlings. The remarshaling is the task of rearranging containers during the idle time of transfer crane for the effective loading operations. This paper proposes a method of planning for remarshaling in a yard block of an automated container terminal. Our method conducts a search in two stages. In the first stage, the target stacking configuration is determined in such a way that the throughput of loading is maximized. In the second stage, the crane schedule is determined so that the remarshaling task can be completed as fast as possible in moving the containers from the source configuration to the target configuration. Simulation experiments have been conducted to compare the efficiency of loading operations before and after remarshaling. The results show that our remarshaling plan is really effective in increasing the efficiency of loading operation.

• Composites Research
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• v.29 no.6
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• pp.353-357
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• 2016

An appropriate way to fabricate a hybrid composite containing evenly dispersed carbon nano tubes(CNTs) is to stacking B-stage resin films that contain evenly dispersed CNTs and various reinforcing fiber layers alternatively. In the present study, B-stage resin films are manufactured via shear mixing and three-roll milling. CNT dispersion in resin via these two processes are evaluated by SEM on their fracture surfaces. For more efficient process, the dispersivities are evaluated according to the number of calendering passes. Samples are made for different number of passes during calendering, and their dispersions are evaluated via SEM fractographs as well as by measuring their electrical conductivities. Additionally, the optimal process conditions are obtained by measuring the electrical conductivity and evaluating their dispersivity of the samples prepared by gap mode and force mode.