• Journal of Korean Society for Quality Management
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• v.27 no.4
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• pp.241-255
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• 1999

This paper concerns Reliability Analysis System(RAS) developed by LG Electronics, Inc. for collecting, classifying, and analyzing field failure data. To develop this system, a database for the management of field failure data was built and several functions were included to analyze and assess the product reliability. Nonparametric estimation and cumulative hazard plotting techniques were applied to estimate the reliability for a specific period. This system serves not only engineers in charge of quality but also designers who wish to monitor the reliability of their own products.

• 한국전산유체공학회:학술대회논문집
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• 2000.05a
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• pp.91-98
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• 2000

The three-dimensional unsteady compressible Full Navier-Stokes equation solver with sliding multi-block method has been applied to analyze three dimensional characteristics of the flow field and compression wave around the high speed train which Is entering into a tunnel. The numerical scheme of AF + ADI was used to efficiently solve Navier-Stokes equations in the curvilinear coordinate system. The vortex formation around the nose region was found and the generation of compression wave due to the blockage effects was observed ahead of the train in the form of plane wave. The three dimensional characteristics of the flow field compared to the analytic results were discussed in detail. The variation of pressure of tunnel wall surface and velocity profile of the train are identified as the train enters into a tunnel. The changes in aerodynamic forces and streamlines of each specific sections are also discussed and presented.

• Journal of Environmental Science International
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• v.6 no.1
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• pp.33-44
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• 1997

In investigating heavy metal contents at specific areas, the method of selecting sampling points is Important A general method is, according to the law , random sampling of zigzag-form in the selected field. In this work, we studied whether the measured values obtained from a certain method of selecting sampling points is a representative of heavy metal contents in the selected field or not. The selected field for this study is located on the lower Yangsan-river: Gasan-li, Mulgum-myon, Yangsan-gun, KyoungNam, 1 km away from the mi, h stream of Nakdong river. The heavy metals investigated were Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn. The inductively coupled plasma(ICPI atomic emission spectrometer was used to measure these metals quantitatively. The number of total sampling points were 24. We compared the total mean values with the mean obtained from various methods of selecting sampling points.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.4
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• pp.520-529
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• 1999

Exposure limits for human protection are determined by converting basic limits for induced current, SAR(specific absorption rate), or power density, which are based upon biological effects, to measurable electric and magnetic field intensities. As a part of studies for the establishment of a domestic guideline for exposure limits, the validity of the exposure limits of five representative guidelines or standards, which are derived from basic limits, are investigated in this paper, using the published results for coupling mechanisms of electromagnetic field into a human body, and problems in each standard are analyzed and compared with each other.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.7
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• pp.923-929
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• 2004

A magnetostrictive sensor is a sensor measuring elastic waves. Because of its unique non-contact measurement feature, the sensor receives more attentions in recent years. These sensors have been mainly used to measure longitudinal and torsional waves in ferromagnetic waveguides, but there increases an interest in using the sensor for flexural wave measurement. Since the performance of the sensor is strongly influenced by the applied bias magnetic field distribution, the design of the bias magnetic system providing the desired magnetic field is critical. The motivation of this investigation is to design a bias magnetic system consisting of electromagnets and yokes and the specific objective is to formulate the design problem as a bias yoke topology optimization. For the formulation, we employ linear magnetic behavior and examine the optimized results for electromagnets located at various locations. After completing the design optimization, we fabricate the prototype of the proposed bias magnetic system, and test its performance through flexural wave measurements.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2006.04a
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• pp.857-864
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• 2006

Due to the difficulties in numerical generation of random fields that satisfy not only the probabilistic distribution but the spectral characteristics as well. it is relatively hard to find an exact response variability of a structural response with a specific random field which has its features in the spatial and spectral domains. In this study. focusing on the fact that the random field assumes a constant over the domain under consideration when the correlation distance tends to infinity, a semi-theoretical solution of response variability is proposed for in-plane and plate bending structures. In this procedure, the probability density function is used directly resulting in a semi-exact solution for the random field in the state of random variable. It is particularly noteworthy that the proposed methodology provides response variability for virtually any type of probability density functions.

• Journal of Advanced Marine Engineering and Technology
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• v.28 no.2
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• pp.185-191
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• 2004

This study describes the scheme of vector drive system without speed sensor for AC servo motor using theory of a flux observer and based on the field oriented vector control. The new method of speed estimation is presented from operate with the position and magnitude of the secondary flux which obtain from the voltage reference and detected current. As the estimated speed is settled by the flux and the machine-specific parameters. this method don't need to adjust the gain of the parameter. Based on the derived theory for vector control. the scheme for sensorless vector drive of AC servo motor is designed and realized. And the experiment verifies it passable to realize the sensorless vector drive based on a field-oriented type.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.618-621
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• 2008

The magnetic recording system shows the difference of the magnetic recording density according to the direction of the magnetic field. The yoke shape of the recording system affects the magnetic field direction; therefore, the recording density may be raised by changing the shape. This paper intends not only to increase the magnetic flux density of the record region but also to reduce the recording loss of a specific region through the simultaneous design of the yoke and the magnet. The recording loss can be reduced by minimizing the magnetic flux of the adjacent area to the recording region. The topology optimization method is used to obtain the optimal shape both of the yoke and the magnet. And the commercial package, Maxwell is used to verify the result.

• Journal of the Korean Society of Marine Environment & Safety
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• v.20 no.3
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• pp.318-322
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• 2014

A kind of field bus called Actuator and Sensor interface bus(AS-i) was designed in this paper. The configuration of AS-i network system used Application Specific Integrated Circuit(ASIC) SAP5S chip and PLC S7-200 station, which included CPU 224 and AS-i master module CP 243-2. We also created an example program for PLC S7-200 to control AS-i network. The fire and smoke detection system was made with AS-i network system that was designed. This system had got more advantages than other system such as number of stations, easy installation, wide working area, etc. And designed system can be used as a partner network for higher level field bus networks.

• Korean Journal of Veterinary Research
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• v.45 no.2
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• pp.199-205
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• 2005

DNA fingerprint patterns of 8 Brucella reference strains and 15 B. abortus field isolates were characterized by repetitive element sequence-based PCR (rep-PCR) using BOX- and ERIC-primers in this study. AMOS PCR differentiated all Brucella field isolates from B. abortus RB51, a vaccine strain by producing a B. abortus-specific 498 bp band. Rep-PCR using BOX-primer produced 13 to 18 bands with sizes of between 230 and 3,300 bp, and discriminated Brucella strains to the species level except B. canis and B. suis. PCR products amplified with ERIC primers were, however, not appropriate for differentiating the Brucella isolates. DNA fingerprint patterns for all B. abortus field isolates were identical among them and were put on one cluster with B. abortus biovar 1 reference strain in the dendrogram, indicating they were highly clonal. These results suggested that rep-PCR using BOX primer might to be a useful tool for calculating genetic relatedness among the Brucella species and for the study of brucellosis epidemiology.