• Transactions of Materials Processing
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• v.20 no.4
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• pp.316-323
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• 2011

The hot curvature-forming of large aluminum thick plate using a grid-typed hybrid die is a process for the production of a spherical LNG tank. Many variables such as the initial die surface quality, grid size, grid thickness, size of blank plate and cooling line design, control the success of the process. In addition, the plate used in this process is generally larger than $10{\times}10m$ in size. Thus, it is very difficult to predict the surface characteristics of the plate during forming and to measure the different parameters due to the high cost of the experiments. In order to optimize the process design for the grid-type die, the development of an analytical method to predict the surface characteristics of the final product in hot curvature-forming is needed. This paper described the development of the method and procedures for FE simulations of the hot curvature-forming process, including hot forming, air flow, cooling, and thermal deformation analyses. An experiment for a small scale model of the process was conducted to check the validity of the numerical method. The results showed that the curvature of the plate in the analysis agrees well with that of the experiment within 0.037 and 0.016% tolerance margins for its side and corner, respectively.

• Transactions of Materials Processing
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• v.23 no.7
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• pp.405-412
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• 2014

As a major type of heat exchanger, the steam generator (SG) produces steam from heat energy of a nuclear power plant reactor. The steam produced by the steam generator flows into a turbine, and plays an important role in electric power generation. The heat transfer tubes in the steam generator consist of approximately 10,000 U-shaped tubes, which perform a structural role and act as thermal boundaries. The heat transfer tubes conduct the thermal energy between the primary coolant (about $320^{\circ}C$, $157kgf/cm^2$) obtained from the reactor and the secondary coolant (about $260^{\circ}C$, $60kgf/cm^2$) as part of the secondary system. Recently, the heat transfer tubes in the steam generator of the pressurized water reactor (PWR) are primarily produced from Alloy 600 and Alloy 690 seamless tubes. As a pilot study to find process parameters for the cold U-bending process using rotary draw bending, numerical and experimental investigations were conducted to produce U-shaped tubes from long straight SUS304L seamless tubes. 3D finite element simulations were run using ABAQUS Explicit with consideration of the elastic recovery. The process parameters studied were the angular speed, the operation period and the bending angle. Experimental verifications were conducted to insure the suitability of the final U-shaped configurations with respect to both ovality and wall thickness.

• Elastomers and Composites
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• v.44 no.4
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• pp.384-390
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• 2009

Roll-to-roll forming process is one of important metal processing technology because the process is simple and economical. These days, with these merits, roll-to-roll forming process is tried to be employed in manufacturing the circuit board, barrier ribs and solar cell plate. The solar cell plate may have millions of patterns, and the analysis of forming considering all the patterns is impossible due to the computational costs. In this study, analyses are carried out for various numbers of patterns and the results are compared. It is shown that the analyses results with four row patterns and twelve row patterns are same. So, it is considered that the analysis can be carried out for only four rows of pattern for the design of incremental roll-to-roll forming process. Also formability is analysed for various number of mesh, protrusion shapes and forming temperature.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.54 no.6
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• pp.255-261
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• 2005

Recently, the RF inductive discharge or inductively coupled plasma continues to attract growing attention as an effective plasma source in many industrial applications, the best known of which are plasma processing and lighting technology. To the point of lighting sources, the ring-shaped electrodeless fluorescent lamps utilizing an inductively coupled plasma have been objects of interest and research during the last decades, mainly because of their potential for extremely long life, high lamp efficacies, rapid power switching response. In this paper, maxwell 3D finite element analysis program (Ansoft) was used to obtain electromagnetic properties associated with the coil and nearby structures. The electromagnetic emitting properties were presented by 3D simulation software operated at 250 kHz and some specific conditions. The electromagnetic field in the ferrite core was shown to be high and symmetric. An LS-100 luminance meter and a Darsa-2000 spectrum analyzer were used in the experiment. According to data on the lamp tested using high magnetic field ferrite, the optical and thermal wave fields were shown to be high around the ring-shaped electrodeless fluorescent lamp. The optical or light field was high at the center of the bulb rather than around the ferrite core. The light conditions of the bulb were assumed to be complex, depending on the condition of the filler gas, the volume of the bulb, and the frequency of the inverter. Our results have shown coupling between the gas plasma and the field of the light emitted to be nonlinear.

• The Journal of the Korea Contents Association
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• v.8 no.9
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• pp.10-18
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• 2008

The most critical element in the real-time operation of RFID application programs that are suitable for the mobile environment is the RFID middleware, made exclusively for mobile handsets, which processes collected data on a real-time basis and sends only the useful information to the application client. In this paper, we intend to design and implement a mobile RFID middleware system that supports the mobile handset environment for real-time based processing of the necessary data in the mobile environment. The proposed mobile RFID middleware system includes a mobile reader interface that collects the tag data, a mobile filtering engine that processes the tag data into more meaningful data that is sent to the application interface, and finally the mobile application interface that supports the m-SOAP application access protocol for interfacing with existing mobile applications. The filtering speed of the newly-developed middleware engine was found to be suitable for the characteristics of mobile handsets.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.3
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• pp.15-24
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• 2015

Jacket matrices which are defined to be $m{\times}m$ matrices $J^{\dagger}=[J_{ik}^{-1}]^T$ over a Galois field F with the property $JJ^{\dagger}=mI_m$, $J^{\dagger}$ is the transpose matrix of element-wise inverse of J, i.e., $J^{\dagger}=[J_{ik}^{-1}]^T$, were introduced by Lee in 1984 and are used for Digital Signal Processing and Coding theory. This paper presents some square matrices $A_2$ which can be eigenvalue decomposed by Jacket matrices. Specially, $A_2$ and its extension $A_3$ can be used for modifying the properties of hyperbola and hyperboloid, respectively. Specially, when the hyperbola has n times transformation, the final matrices $A_2^n$ can be easily calculated by employing the EVD[7] of matrices $A_2$. The ideas that we will develop here have applications in computer graphics and used in many important numerical algorithms.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.2
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• pp.451-456
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• 2016

Because GPS signals are weak, system jamming is a real and present danger. This can happen when the receiver is subjected to intentional or unintentional interference by a transmitter. If the jamming signal is strong enough, the receiver can be operated to take corrective action automatically. Current methods to protect GPS receiver from jamming condition are based on spatial filtering. In this paper, the beamforming as referred to in signal processing technique used in arrays for directional signal reception was suggested and analyzed for anti-jamming. In order to change the directionality of the array when receiving a jamming signal, a beamformer can control the signal at each sensor. Therefore, cutoff angle ${\theta}$ was measured in the opposite direction of the jammer. GPS signals are only processed when the antenna element is within inside the cutoff angle. As a result, GPS positioning can be used in condition under cutoff angle $30^{\circ}$.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.10a
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• pp.530-532
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• 2018

Digital imaging equipment has been used for a variety of purposes in a wide range of society and has become an important element of the fourth industrial revolution. However, there are various causes of noise in the process of transmitting / receiving data and processing of the equipment, thus affecting the accuracy and reliability of the equipment. In this paper, we propose an image restoration algorithm based on pixel range set by standard deviation to effectively remove Salt and Pepper noise. In the conventional methods, the performance degrades in the edge and high frequency components of the image. However, the proposed method has better noise reduction performance than the conventional method by performing the noise elimination considering the image boundary. It has confirmed that the performance of such PSNR and magnified image, the experimental results showed that the proposed algorithm superior compared to existing methods.

• The KIPS Transactions:PartD
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• v.8D no.3
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• pp.241-246
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• 2001

Area of software measurement in software engineering is active more than thirty years. There is a huge collection of researches but still no a concrete software cost estimation model. If we want to measure the cost-effort of a software project, we need to estimate the size of the software. A number of software metrics are identified in the literature ; the most frequently cited measures are LOC(line of code) and FPA(function point analysis). The FPA approach has features that overcome the major problems with using LOC as a measure of system size. This paper presents an neural networks(NN) models that related software development effort to software size measured in FPs and function element types. The research describes appropriate NN modeling in the context of a case study for 24 software development projects. Also, this paper compared the NN model with a regression analysis model and found the NN model has better estimative accuracy.

• The KIPS Transactions:PartB
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• v.10B no.5
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• pp.543-552
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• 2003

An increasing in quantity of multimedia data brought a new problem that expected data should be retrieved fast and exactly. The adequate representation is a key element for the efficient retrieval. For this reason, MPEG-7 standard was established for description of multimedia data in 2001. However, the content of the standard is massive and the approach method is not clear for real application system yet, because of properties of MPEG-7 standard that has to include a lot of potential cases. In this paper, we suggested implementation scheme of retrieval system with using of only visual descriptors and presented the performance results of developed system. From the result of developed system, MPEG-7 VIRS (Video/Image Retrieval System), we analyzed the retrieval results between using individual descriptor and using multiple descriptors, and showed a layout for real application system.