• Journal of the Korea Convergence Society
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• v.10 no.12
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• pp.287-292
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• 2019

This paper analyzes the thermal behaviors of genuine discs used in automobiles and discs coming out of tuning products through FEM analysis. Modeling with genuine disk modeling and tuning disks Model-1, Model-2, Model-3 and analyzing the disk rotation speed was set to 1000rpm. When the brake is operated, the thermal behavior of the disk surface, such as the operating temperature caused by the disk and pad contact, the friction surface temperature after the disk stop, and the thermal deformation, were analyzed. When the brake was activated (0-4.5 seconds), the tuning disk showed 34℃ higher than the original disk, and after the disk stopped (40.5 seconds), the tuning disk was analyzed 18℃ lowe, deformation due to the disk heat was deformed by 0.3mm for the tuning disk. Although there is an effect to reduce the fading phenomenon due to the thermal behavior of the pure disk and the tuning disk, it can be observed that there is no significant change in the thermal behavior due to the hole processing and the disk surface processing of the tuning disk.

• Interaction and multiscale mechanics
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• v.2 no.1
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• pp.45-68
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• 2009

An aim of the study is to develop an efficient numerical simulation technique that can handle the two-scale analysis of fluid permeation filters fabricated by the partial sintering technique of small spherical ceramics. A solid-fluid mixture homogenization method is introduced to predict the mechanical characters such as rigidity and permeability of the porous ceramic filters from the micro-scale geometry and configuration of partially-sintered particles. An extended finite element (X-FE) discretization technique based on the enriched interpolations of respective characteristic functions at fluid-solid interfaces is proposed for the non-interface-fitted mesh solution of the micro-scale analysis that needs non-slip condition at the interface between solid and fluid phases of the unit cell. The homogenization and localization performances of the proposed method are shown in a typical two-dimensional benchmark problem whose model has a hole in center. Three-dimensional applications to the body-centered cubic (BCC) and face-centered cubic (FCC) unit cell models are also shown in the paper. The 3D application is prepared toward the computer-aided optimal design of ceramic filters. The accuracy and stability of the X-FEM based method are comparable to those of the standard interface-fitted FEM, and are superior to those of the voxel type FEM that is often used in such complex micro geometry cases.

• Journal of the Korean Society for Nondestructive Testing
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• v.33 no.1
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• pp.73-79
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• 2013

In this study, NIMAX material has been processed using the three-dimensional measuring instrument and white light interferometer. they were tested to roundness and surface roughness and results are as follows: As for a cutting characteristic, it indicated that F4 showed a lower result than 2F showed due to the high hardness of the material and showed a good result when spindle rotation speed and tool feed were low. As for the measurement of roundness through 3-Dimensional measuring machine, it indicated that 4F showed a good result like the condition of cutting component and that roundness showed a good result when spindle rotation speed of 1,700 rpm and tool feed speed of 85 mm/min were applied. As for the surface roughness of processing surface, Surface roughness showed better 4F than 2F and conditions of spindle rotation speed 1,700 rpm, tool feed rate 55 mm/min showed good results in the Ra $0.4025{\mu}m$.

• Journal of the Institute of Convergence Signal Processing
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• v.20 no.4
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• pp.199-204
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• 2019

In the boundary layer, vortical system has been analyzed by the statistical methods to identify the vortex interaction. However, there are the limitations in explaining vortices by the mean velocity or the standard deviation. This paper proposed a method to establish a frequency analysis by Fourier transform in order to simultaneously investigate various scale vortices. For this purpose, the flow visualization conducted to reveal a standing vortex, a hairpin vortex and a wake region around a hemisphere attached on a flat plate in a water channel. In addition, the velocity where the hairpin vortex was being generated in the wake region was measured by a hot-film anemometer. To observe changes in the vortex interaction, suction was applied through a hole in front of the hemisphere. For the evaluation of the proposed frequency analysis, the existing statistical results were compared to the frequency analysis that corresponds to the qualitative results of the flow visualization.

• Journal of Korean Society of Forest Science
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• v.94 no.6
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• pp.377-386
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• 2005

This study was carried out to analyse the landslide characteristics by ground investigation, borehole image processing system, field seismic test, laboratory test and ground stability analysis at the landsliding area occurred in Maeri, Sangdong-myeon, Gimhaesi, Gyeongsangnam-do. Region I needs to install data logger system to monitor a land displacement during the heavy rainfall events because the region can be liable to occur the land slide by land creeping. It is needed to restore rapidly, if the land displacement occurs in Region I. Region II needs to monitor and repair because of the possibility of slope failure by long-term soil loss. Region III needs constructions to remove ground runoff and ground water to be infiltrated from talus. Region IV where is a stable region, needs to be protected from land cutting or other man-made damage.

• Journal of KIISE:Software and Applications
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• v.32 no.7
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• pp.625-635
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• 2005

In this paper, we propose a hybrid approach for segmenting the lungs efficiently and automatically in chest CT images. The proposed method consists of the following three steps. first, lungs and airways are extracted by two- and three-dimensional automatic seeded region growing and connected component labeling in low-resolution. Second, trachea and large airways are delineated from the lungs by two-dimensional morphological operations, and the left and right lungs are identified by connected component labeling in low-resolution. Third, smooth and accurate lung region borders are obtained by refinement based on image subtraction. In experiments, we evaluate our method in aspects of accuracy and efficiency using 10 chest CT images obtained from 5 patients. To evaluate the accuracy, we Present results comparing our automatic method to manually traced borders from radiologists. Experimental results show that proposed method which use connected component labeling in low-resolution reduce processing time by 31.4 seconds and maximum memory usage by 196.75 MB on average. Our method extracts lung surfaces efficiently and automatically without additional processing like hole-filling.

• Journal of the Korean Society for Nondestructive Testing
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• v.15 no.4
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• pp.531-539
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• 1996

The research for the classification of the artificial defects in welding parts is performed using the pattern recognition technology of ultrasonic signal. The signal pattern recognition package including the user defined function is developed to perform the digital signal processing, feature extraction, feature selection and classifier selection. The neural network classifier and the statistical classifiers such as the linear discriminant function classifier and the empirical Bayesian classifier are compared and discussed. The pattern recognition technique is applied to the classification of artificial defects such as notchs and a hole. If appropriately learned, the neural network classifier is concluded to be better than the statistical classifiers in the classification of the artificial defects.

• Journal of the Korea Computer Graphics Society
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• v.24 no.3
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• pp.43-48
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• 2018

In this paper, we present a method for removing shadows from scanned documents. Compared to the existing methods such as one based on image pyramid representation or adaptive thresholding, our method produces more robust and higher quality results. The basic idea of the approach is to use the local image statistics and to separate interesting regions from the image such as the regions around letters and figures. For the separated regions, we adaptively adjust the local brightness and contrast, and apply the sigmoid function to the intensity values as well to enhance the clarity of the image. For separated the other empty regions, we apply the gradient-base image hole filling method to fill the region with smooth color change.

• Proceedings of the IEEK Conference
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• 2001.09a
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• pp.777-783
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• 2001

This paper is mainly concerned with the state of the practical developments of a constants PWM bridge type resonants DC-DC suitable converter for Nd:YAG Laser with a Microprocessor. (PIC16C54 & 8051) The use of IGBT power supply with feedback control of flashLamp currents imparts a advantages to Nd:YAG Laser for materials processing. these include the alility to tailor the pulseshape and modify pulse parameters on a pulse- by pulse basis. And Correct choice of pulseshape can enhance the repeatability of the process. as higher power IGBT became available, act ive pulseforming power supplies will find greater user in deep hole drilling machine By Using certain control tecniques, utililized in designing Pic16c54 from Microchip technology and Intel 8051, also Mornitoring from Microsoft Visual Basic 5, And it allowed us to designed and fabricate ahigh repel it ion rate and high power(HRHP) pulsed Nd:YAG laser system, As a result of that, the current pulsewidth could be contort led 200s to 350s(step 50s) , and the pulse repetition rate could be adjusted 500pps to 1150pps. In addition, in the case of one laser head consisting of a Nd:YAG laser rod and two flashlamps , the maximum laser output of 240w was produced at the condition of 350s and 1150pps, and that of about 480w was generated at the same condition when two laser heads were arranged in cascade.

• Journal of ILASS-Korea
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• v.10 no.1
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• pp.17-23
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• 2005

Even though a relatively complete knowledge base has been established for diesel sprays, much of the knowledge cannot be directly translated to correlate the characteristics of gasoline spray. The macroscopic characteristics of gasoline impingement spray was investigated with photographic and image processing technique by Particle Motion Analysis System. The injector with single hole nozzle diameter of 0.28 mm was used in this experiment and the injection duration was selected as 10 msec. The injection pressure with 0.3, 0.35, and 0.4 MPa, impingement distance or 70, 100 and 130m, impingement angle or 0.15, 30 and $45^{\circ}$ were employed for the variables to affect the spray characteristics of impinging spray. It is clear that there is the analogy on the spray tip penetration between the gasoline impinging jet and diesel free jet. The spray tip penetration of impinging gasoline spray is proportional to the quarter power of the time after start of injection. The maximum height of impinging gasoline spray is also proportional to the quarter power of the time regardless of impingement distance, impingement angle and injection pressure. In addition, the effect of impingement angle on the spray tip penetration is significant according to the time after start of injection, even though there is minor effect in the initial stage of time after start of injection. Moreover, there is no remarkable effect of injection pressure on the spray tip Penetration under the experimental condition used in this study.