• Journal of Power Electronics
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• v.12 no.5
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• pp.787-799
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• 2012

Real and reactive power flows on a transmission line interact inherently. This situation degrades power flow controller performance when independent real and reactive power flow regulation is required. In this study, a quasi multi-pulse interline power flow controller (IPFC), consisting of eight six-pulse voltage source converters (VSC) switched at the fundamental frequency is proposed to control real and reactive power flows dynamically on a transmission line in response to a sequence of set-point changes formed by unit-step reference values. It is shown that the proposed hybrid fuzzy-PI commanded IPFC shows better decoupling performance than the parameter optimized PI controllers with analytically calculated feed-forward gains for decoupling. Comparative simulation studies are carried out on a 4-machine 4-bus test power system through a number of case studies. While only the fuzzy inference of the proposed control scheme has been modeled in MATLAB, the power system, converter power circuit, control and calculation blocks have been simulated in PSCAD/EMTDC by interfacing these two packages on-line.

• Design & Manufacturing
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• v.10 no.2
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• pp.29-33
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• 2016

Production machines have been more important, due to quality level of vehicle motor core is getting higher. That is why, to improve assembly fit of tooling and to be emphasized how much moving down caused of deterioration of high speed press, it is also getting more important parts as solution of problems. To analyze how much move based on condition of movement as tooling and high speed press, and to measure how much impact to embossing height caused of changing movement down. As the result of investigation, in case of material thickness 0.5mm, there is highest pull and force power when emboss height is 0.45mm. If emboss height is less than 0.45mm, pull and force power is getting lower, if emboss height is higher than 0.45mm, it is impossible to make it forming caused of changed press movement, also it has been piercing.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.1
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• pp.99-105
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• 2004

The car seat head restraint is used for neck injury(whiplash injury) prevention in rear end impacts. The purpose of this study was to evaluate the seat head restraints for the total number of 34 domestic cars. H-POINT machine and HRMD(head restraint measuring device) were applied to measure backset(the distance between head and seat head restraint) and height(height gap between head and seat head restraint). For tendency study of driver's head position, we took the 320 driver's pictures in the street. As results, There were only five percent drivers in good and acceptable zone. For car seat head restraint system, the results was 9 cars for good zone, 10 cars for acceptable zone, 9 cars for marginal zone and 6 cars for poor zone were evaluated. For a precise evaluation the of whiplash injury, detailed FE neck model will be developed and the clinical database should be constructed for model validation.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.6
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• pp.516-521
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• 2009

X-ray system which is usefully used in diagnosis of the patient, being bombed of radioactivity is a big weak point when irradiates a X-ray to the human body so that ICRP restricted the radiation exposure tolerance of the human body. In order to reduce being bombed, the many research and development is now advanced. A lots of diagnostic X-ray machines have currently used due to the increase of occurrence efficiency of X-ray and precisely the output control by using the inverter which is a high speed switching semiconductors. For getting the confidence of the X-ray machine, the same radiation occurrence, same evaluation, and same irradiation condition are necessary when evaluates X-ray irradiation. It is the most important part for the accuracy of the test result and the patient safety. This research has produced the high voltage occurrence system of full-wave rectification method by using the LC resonance inverter, and evaluated the irradiation reproducibility in order to use it in diagnosis of the patient.

• Korean Journal of Materials Research
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• v.21 no.12
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• pp.650-654
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• 2011

In this paper, the effects of conventional and newly developed elastomer modified underfill materials on the mechanical shock reliability of BGA board assembly were studied for application in mobile electronics. The mechanical shock reliability was evaluated through a three point dynamic bending test proposed by Motorola. The thermal properties of the underfills were measured by a DSC machine. Through the DSC results, the curing condition of the underfills was selected. Two types of underfills showed similar curing behavior. During the dynamic bending reliability test, the strain of the PCB was step increased from 0.2% to 1.5% until the failure circuit was detected at a 50 kHz sampling rate. The dynamic bending reliability of BGA board assembly using elastomer modified underfill was found to be superior to that of conventional underfill. From mechanical and microstructure analyses, the disturbance of crack propagation by the presence of submicron elastomer particles was considered to be mainly responsible for that result rather than the shear strength or elastic modulus of underfill joint.

• Journal of Mechanical Science and Technology
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• v.20 no.6
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• pp.874-881
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• 2006

Combustion stability characteristics in actual full-scale combustion chamber of a rocket engine are investigated by experimental tests with the model (sub-scale) chamber. The present hot-fire tests adopt the combustion chamber with three configurations of triplet impinging-jet injectors such as F-O-O-F, F-O-F, and O-F-O configurations. Combustion stability bound-aries are obtained and presented by the parameters of combustion-chamber pressure and mixture (oxidizer/fuel) ratio. From the experimental tests, two instability regions are observed and the pressure oscillations have the similar patterns irrespective of injector configuration. But, the O-F-O injector configuration shows broader upper-instability region than the other configurations. To verify the instability mechanism for the lower and upper instability regions, air-purge acoustic test is conducted and the photograph or the flames is taken. As a result, it is found that the pressure oscillations in the two regions can be characterized by the first impinging point of hydraulic jets and pre-blowout combustion, respectively.

• Journal of Internet Computing and Services
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• v.5 no.2
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• pp.1-15
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• 2004

The current Internet space is evolving to the so called Ubiquitous space. Unlike the Internet space, the information in the Ubiquitous space is distributed evenly in the places like computer's memory, human's brain and physical machine. The 'hypertext', the connection model of the information, which is originally designed for the Internet space doesn't suit well to the Ubiquitous space. From this point of view, we proposed the CPM model in this paper. The CPM model is designed for comprising the such three computing mechanism as analog computing, digital computing and human computing. In this paper, we showed that the characteristics of the CPM model might answer the such purpose as the connection of information in the Ubiquitous space.

• Journal of Institute of Convergence Technology
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• v.6 no.1
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• pp.23-26
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• 2016

DC motor shafts have several defects such as double cut, deep scratch on surface, and defects in diameter and length. The deep scratches are due to collision among the other shafts. So the scratches are long and thin but their orientations are random. If the smallest enclosing box, i.e. oriented bounding box for a detective point group is found, then the size of the corresponding defect can be modeled as its diagonal length. This paper proposes an suface inspection algorithm for the DC motor shaft using the oriented bounding box. To evaluate the proposed algorithm, a test bed is made with a line scan CCD camera (4096 pixels/line) and two rollers mechanism to rotate the shaft. The experimental result on a pre-processed image with contrast streching algorithm, shows that the proposed algorithm sucessfully finds 150 surface defects and its computation time (0.291 msec) is enough fast for the requirement (4 seconds).

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.12 no.3
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• pp.250-255
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• 2012

Face recognition has wide applications in security and surveillance systems as well as in robot vision and machine interfaces. Conventional challenges in face recognition include pose, illumination, and expression, and face recognition at a distance involves additional challenges because long-distance images are often degraded due to poor focusing and motion blurring. This study investigates the effectiveness of applying photon-counting linear discriminant analysis (Pc-LDA) to face recognition in harsh environments. A related technique, Fisher linear discriminant analysis, has been found to be optimal, but it often suffers from the singularity problem because the number of available training images is generally much smaller than the number of pixels. Pc-LDA, on the other hand, realizes the Fisher criterion in high-dimensional space without any dimensionality reduction. Therefore, it provides more invariant solutions to image recognition under distortion and degradation. Two decision rules are employed: one is based on Euclidean distance; the other, on normalized correlation. In the experiments, the asymptotic equivalence of the photon-counting method to the Fisher method is verified with simulated data. Degraded facial images are employed to demonstrate the robustness of the photon-counting classifier in harsh environments. Four types of blurring point spread functions are applied to the test images in order to simulate long-distance acquisition. The results are compared with those of conventional Eigen face and Fisher face methods. The results indicate that Pc-LDA is better than conventional facial recognition techniques.

• Tribology and Lubricants
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• v.35 no.5
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• pp.317-322
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• 2019

In spite of progress in tribological research, machine component failure due to friction and wear has been reported frequently. This failure may lead to secondary damage that can cause huge expense for maintenance and repair. To prevent economic loss, it is important to detect and predict the initial failure point. In this sense, various researchers have been tried to develop Condition Monitoring (CM) method using Acoustic Emission (AE) generated while the materials undergo failure. In this study, effect of particles on friction and wear was investigated using the pin-on-plate friction test and AE signal was recorded with a band-width type AE sensor. The experiments were performed in dry and lubricant conditions using steel and glass as specimens. After the experiment, 3D laser microscope image was captured to evaluate the wear behavior quantitatively. The AE signal was analyzed in time-domain and frequency-domain. The amplitude was compared with the frictional results. The results of this study showed that particle generation accelerate wear, generate high magnitude AE signal and change the frequency characteristics of the signal. Also, lubricant condition test results showed low coefficient of friction, low wear rate, and low magnitude of AE signal compared to the dry condition. It is expected that the results of this study will aid in better assessment of wear in CM technology