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Yanggu, South Korea

Hong S.-H.,Dongyang Technical College | Kim B.-K.,Korea University
IEEE Transactions on Consumer Electronics | Year: 2010

In the future ubiquitous home network, sensors will collect various home environment data in the home. Since the sensor nodes are equipped with small, often irreplaceable, batteries with limited power capacity, it is essential that the network be energy-efficient in order to maximize its lifetime. Our study, described in this paper, was divided into two classes: The primary class was to set a gateway-selection level and the secondary class was to propose an offer of a home automation using a routing technique centered on a sensor network to set a flooding level. The proposed scheme is to increase the life time of the sensor network with the integrated gateway node. The IGN increases the life time of the network to integrate the multiple gateway nodes © 2006 IEEE.

Park H.,Korea Institute of Industrial Technology | Cha B.,Korea Institute of Industrial Technology | Cho S.,Dongyang Technical College | Kim D.,Ajou University | And 3 more authors.
International Journal of Advanced Manufacturing Technology | Year: 2015

Insert parts in insert injection molding used to be deformed by pressure developed during the molding process. The plastic deformation of insert parts caused by injection pressure during insert injection molding for electric power plugs cannot be predicted by conventional injection molding analysis methods. In this study, the injection-structural coupled analysis was carried out to predict the plastic deformation of insert parts. Injection pressure developed during the molding process was calculated by the injection molding analysis software and was mapped onto the grid surface of the inner tube model for structural analysis as boundary conditions. The effect of process parameters such as injection time, melt temperature, and holding pressure on the injection pressure and the deformation of the inner tubes was examined to find the proper molding condition. The result from the analysis was compared to the insert injection molding experiment. Furthermore, the diameters of sub-runners in the multi-cavity mold of the power plugs were optimized to prevent the deformation of the inner tubes by the unbalanced filling of the melt into the linear arranged cavities using the injection-structural coupled analysis. © 2015 Springer-Verlag London

Kim B.-K.,Korea University | Hong S.-H.,Dongyang Technical College | Hur K.,Gyeongin National University of Education | Eom D.-S.,Korea University
IEEE Transactions on Consumer Electronics | Year: 2010

To synchronize clocks of nodes with low energy use and in short time in WSNs, this paper focuses on the reduction of the number of transmissions and on the message forwarding amongst sensor nodes. And we present a method, which is called EETS (Energy-Efficient Time Synchronization). The EETS method decreases the number of messages for the time synchronization and the messages could be rapidly passed through the network. Additionally, the WSNs are finally able to save energy. Through the performance comparisons of existing algorithms and the EETS with a network simulator and analysis, we show the performance evaluations of the EETS and the improved energy efficiency of the proposed algorithm for the Time Synchronization in the WSNs. © 2006 IEEE.

Cho S.,Dongyang Technical College | Chang T.-E.,Samsung | Lee J.Y.,Samsung | Park H.-P.,Korea Institute of Industrial Technology | And 2 more authors.
Microelectronics Reliability | Year: 2010

Printed Circuit Board (PCB) warpage increases as thickness decreases and ultimately is attributed to CTE mismatch and thickness geometry of the components. Recently, a thin Ball Grid Array (BGA) PCB has been developed due to the advantages like high electrical translation speed with low signal noise. Large warpage severely limited by BGA PCB performance leads to reliability issues modes such as crack and delamination between interconnection components. This is why a dummy design on a BGA PCB and metal stiffener on a Flip Chip (FC) BGA PCB warpage are analyzed experimentally. At the first step, new dummy design in BGA PCB (BoC type) is proposed to reduce warpage. The new dummy design is shaped as a bar. Results of the statistical experimental analysis show PCB warpage using the new dummy design is significantly reduced compared to the use of a PCB with a conventional dummy design. Furthermore, the new dummy design decreases PCB warpage by about 67%. These results signify that the stiffness of the BoC PCB is improved by the new dummy design because the bar-shaped Cu pattern in the dummy acts as a rigid bar stiffener. At the second step, metal stiffener effect is studied to reduce coreless FCBGA PCB warpage. Coreless FCBGA PCB, coreless FCBGA package, and specimens with non-symmetric structure are considered to determine metal stiffener effect on warpage. The experimental results show that metal stiffener has high stiffness, and it seems very effective on reducing average and standard deviation of coreless PCB warpage. © 2009 Elsevier Ltd. All rights reserved.

Kang D.-W.,Hanyang University | Go S.-C.,Hanyang University | Won S.-H.,Dongyang Technical College | Lim S.-B.,Korea Institute of Energy Technology Evaluation and Planning | Lee J.,Hanyang University
Journal of Magnetics | Year: 2010

The multi-degrees of freedom surface permanent-magnet motor (Multi-D.O.F. SPM) has several degrees of freedom operations that are defined as the "roll", "yaw", and "pitch". Normally, the torque that is generated to rotate a rotor includes ripples. The analysis of the torque ripples is important for improving motor performance. In terms of the electric analysis, torque ripple occurs as a result of many factors, including the rotor and stator structures, the distribution of the air-gap flux density, and the waveform of the current in the coils. In particular, the torque ripple is an important factor in the stable operation of the Multi-D.O.F. SPM. Therefore, in this work, the torque ripple was analyzed using various types of magnetization for the permanent magnet. An improved model was proposed for the Multi-D.O.F. SPM based on this analysis. © 2010 Journal of Magnetics.

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