• Proceedings of the KIEE Conference
• /
• 2001.04a
• /
• pp.19-21
• /
• 2001

Induction motors are a critical component of many industrial machines and are frequently integrated in commercial equipment. The many economical losses and the deterioration of system reliability might be caused by the failure of induction motors in industrial field. Based on the reliability and cost competitiveness of driving system(motors), the faults detection and diagnosis of system is considered very important factors. In order to perform the faults detection and diagnosis of motors, the vibration monitoring method and motor current signature analysis (MCSA) method are emphasized. In this paper, MCSA method is used for induction motor fault diagnosis. This method analyzes the motor's supply current, since this diagnoses the motor's condition. The diagnostic system is constructed by using LabVIEW of National Instruments.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2008.05a
• /
• pp.387-390
• /
• 2008

Electromagnetic forming (EMF) technology, which is one of the high speed forming methods, has been used for the forming process in various industry fields. Numerical approach by finite element simulation of the EMF process is presented in this study. The implicit code is used to obtain the numerical model of the time-varying currents that are discharged through the coil in order to obtain the transient magnetic forces. In addition, the body forces generated in the workpiece are used as the loading condition to analyze deformation of thin sheet metal workpiece using explicit code. Numerical approach for a dimpled shape by EMF process is carried out and the simulated results of the dimpled shape by EMF are reviewed in view of the deformed shape and formability evaluation.

• Computers and Concrete
• /
• v.1 no.3
• /
• pp.249-260
• /
• 2004

The stress transmission mechanism in pretensioned concrete beams, though very interesting from an economical point of view, is very complex, integrating various phenomenons such as sliding, bond, bursting. For long the complexity of this mechanism has led engineers to provide a massive rectangular anchorage zone at each end of the beam. The necessity of using such a concrete reinforcement is certainly unquestionable in post-tensioned beams. However in pretensioned elements the stresses induced in concrete in the anchorage zone are smaller than in post-tensioned elements. In this article the stress field in the end zone is calculated numerically and from this analysis the possible reduction of the cross-section of the anchorage block is examined.

• Journal of Ocean Engineering and Technology
• /
• v.15 no.3
• /
• pp.9-19
• /
• 2001

In this paper we present the aspect of inertial oscillation typically observed in the spin-up of fluids at low Rossby numbers in a circular cylinder. Numerical computations for the quasi three-dimensional equation as well as one-dimensional equation are performed to estimate the predictability of the one-dimensional equation with Ekman pumping/suction models. It is assumed that the discrepancy between the two results may be attributed to the inertial oscillation The detailed analysis to the numerical results reveals that the axial plane is dominated by a comparatively strong oscillatory flows caused by the inertial oscillation. In view of the fact that the time-averaged flow field however agrees to the Taylor-Proudman theorem, it is recommended that further analysis is needed to obtain an improved one-dimensional model like the Reynolds-averaged Navier-Stokes equation for turbulent flows.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.33 no.3
• /
• pp.261-264
• /
• 2009

We present a three-dimensional (3D) particle focusing channel using the positive dielectrophoresis (pDEP) guided by a dielectric structure between two planar electrodes. The dielectric structure between two planar electrodes induces the maximum electric field at the center of the microchannel, and particles are focused to the center of the microchannel by pDEP as they flow from the single sample injection port. Compared to the previous 3D particle focusing methods, the present device achieves the simple and effective particle focusing function without any additional fluidic ports and top electrodes. In the experimental study, approximately 90 % focusing efficiency were achieved within the focusing length of 2mm, on both x-z plane (top-view) and y-z plane (side-view) for $2{\mu}m$-diameter polystyrene (PS) bead at the applied voltage over 15 Vp-p (square wave) and at the flow rate below 0.01 ${\mu}l$/min. The present 3D particle focusing channel results in a simple particle focusing method suitable for use in integrated microbiochemical analysis system.

• Proceedings of the KSR Conference
• /
• 2007.05a
• /
• pp.824-828
• /
• 2007

With increasing interest in the reduction of cost for operation and maintenance of overhead catenary system, various methods of condition monitoring have been developed and used in with high-speed analysis and advanced image processing techniques. This study utilizes a high-speed camera as inspecting system to measure the wear, stagger, hight and arc extinguishing test of overhead catenary system. All measuring image were captured by a high speed CMOS camera with PCI express output, which can acquire up to 1000 frames per second with the resolution 1024 × 1280 pixels. Line type laser source with a power equal to 300 mW and the National Instrument LabVIEW (8.0) based on vision acquisition software have been used in application programming interface for image acquisition, display, and storage. The proposed high-speed camera system is finally applied to measure the overhead catenary system showing promising on-field applications

• Journal of Fashion Business
• /
• v.12 no.4
• /
• pp.158-169
• /
• 2008

This study aims to survey the perceptions held by students and field workers regarding the clothing-related qualification certificates, which can serve as the base for becoming clothing professionals, to compare and analyze the actual state of qualification certificates on the basic research level, and thus to search for the directions suitable for the clothing-related qualification certificates. The questionnaire method was selected for the study. The responses of 406 copies from students and 81 copies from field workers were used, and frequency analysis and t-test were done with the assistance of spss 10.0 statistics program, The findings are as follows. First, as to the qualification certificates perceived by the students, the certificates of colorist engineer and colorist industrial engineer were known most. 237 students, or 58.4% of the student respondents, had obtained the information about the qualification certificates mainly through the internet and mass media, and 77.3% of the students had a plan to get the qualification certificates. Second, as to the qualification certificates perceived by the field workers, the respondents indicated that school grades(43.2%) would be given the highest additional points at the time of employment, while the clothing-related qualification certificates gathered low responses of 11.1%. The field workers perceived that the qualification certificate of Western suit engineer(pattern) was needed for the job, while 45.4% of them perceived that no qualification certificate was required for the job. Third, both the students and the field workers showed low acquisition levels of the qualification certificates, and in view of their perceptions that the qualification certificates of languages or computer skills were more useful, the improvement is needed in order for the national certificates for the clothing-related skill qualification to develop in the more job-related directions.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.16 no.12 s.103
• /
• pp.1222-1228
• /
• 2005

Analysis on the field uniformity inside of a reverberation chamber was done at 2.45 GHz which is an operating frequency of MWO(Microwave Oven). The Schroeder's Quadratic Residue Diffuser was designed for the chamber, and 3 different types of diffusers have been investigated using the finite-difference time-domain(FDTD) method for the field characteristics of each type. Type 2 and 3 diffusers were filled with dielectric material, and the size of these could be designed smaller than Type 1, without degradation of field characteristic. Type 3 diffuser shows better results among the three types of diffusers in view of increased test region and better field uniformity.

• Journal of Astronomy and Space Sciences
• /
• v.23 no.4
• /
• pp.415-424
• /
• 2006

In this paper, requirements of Meteorological Administration about Meteorological Image. (MI) of Communications, Ocean and Meteorological Satellite (COMS) is analyzed for the design of COMS ground station and according to the analysis results, the distribution image size of each observation area suitable for satellite Field Of View (FOV) stated at the requirements of meteorological administration is determined and the precise satellite FOV and the size of distribution image is calculated on the basis of the image size of the determined observation area. The results in this paper were applied to the detailed design for COMS ground station and also are expected to be used for the future observation scheduling and the scheduling of distribution of user data.

• Therapeutic Science for Rehabilitation
• /
• v.9 no.1
• /
• pp.45-55
• /
• 2020

Objective : The purpose of this study was to investigate the effects of visual perception on driving performance and the importance of visual training for improving driving performance in patients with stroke. Methods : The evaluations, using MVPT(Motor-free Visual Perception Test), TMT A&B(Trail Making Test A & B), UFOV(Useful Field Of View test), and a driving simulator, were carried out with patients in department of physical medicine and rehabilitation in a rehabilitation hospital from October 2014 to November 2014. Results : Driving performance was related to the ability of various visual perceptions of patients with stroke, and the highest correlation was found in the UFOV subtest 2, TMT B, and MVPT. The results of discriminant analysis indicated a sensitivity of 100.0%, specificity of 80.0%, and predicted the results of the driving simulator with 89.5% accuracy. Conclusion : This study found that visual-perception skills influence driving performance and suggested the importance of visual-perception skill training for driving.