• The Transactions of the Korea Information Processing Society
• /
• v.7 no.7
• /
• pp.2179-2187
• /
• 2000

This paper provides a heuristic analysis technique which determines an optimal number of V\ulcorner/V\ulcorner pads meeting allowable Simultaneous Switching Noise(SN) budget, early in the design phase. Until now, in determining the number of V\ulcorner/V\ulcorner pads, designers had to simulate packaging models case by case in the design phase or roughly allocate the power/ground pins in an inaccurate way according to typical design rules. However, due to the high density and frequency trends of IC technologies, the V\ulcorner/V\ulcorner pads allocation method can affect an adverse effect on IC operations, which requires more accurate and efficient methods be devised. Thus, this paper proposes an analytic V\ulcorner/V\ulcorner pads calculation method that gives a practical help for packaging designs early in the design phase. The proposed method is applied to a design example of a 1/8x208 pin plastic quad flat package (PQFP) and the results are verified through simulation using HSPICE.

• International Journal of Precision Engineering and Manufacturing
• /
• v.1 no.1
• /
• pp.133-145
• /
• 2000

Plastic molding designers are frequently faced with optimizing multiple defects in injection molded parts. these defects are usually in conflict with each other, and thus a tradeoff needs to be made reach a final compromised solution. In this study, an automated injection molding design methodology has been developed to optimize multiple defects of injection molded parts. Two features of the proposed methodology are as follows: one is to apply the utility theory to transform the original multiple objective optimization problem into single objective optimization problem with utility as objective function, the other is an implementation of a direct search-based injection molding optimization procedure with automated consideration of process variation. The modified complex method is used as a general optimization tool in this research. The developed methodology was applied to an actual molding design and the results showed that the methodology was useful through the CAE simulation using a commercial injection molding software package. Applied to production, this study will be of immense value to industry in reducing the product development time and enhancing the product quality.

• Earthquakes and Structures
• /
• v.15 no.2
• /
• pp.123-132
• /
• 2018

In this paper the strain energy density (SED) model is used to analyze the seismic behavior of suspen-domes and a new criterion is established for judging the seismic failure based on a characteristic point in the SED model. Firstly, a nonlinear time-history response analysis was carried out using the finite-element package ANSYS for typical suspen-domes subjected to different ground motions. The seismic responses including nodal displacements, ratios of yielding members, strain energy density and structural maximum deformation energy were extracted corresponding to the increasing peak ground acceleration (A). Secondly, the SED sum ($I_d$) was calculated which revealed that the $I_d-A$ curve exhibited a relatively large change (called a characteristic point) at a certain value of A with a very small load increment after the structures entered the elastic-plastic state. Thirdly, a SED criterion is proposed to judge the seismic failure load based on the characteristic point. Subsequently, the case study verifies the characteristic point and the proposed SED criterion. Finally, this paper describes the unity and application of the SED criterion. The SED method may open a new way for structural appraisal and the SED criterion might give a unified criterion for predicting the failure loads of various structures subjected to dynamic loads.

• Journal of the Korean Society for Precision Engineering
• /
• v.17 no.9
• /
• pp.210-221
• /
• 2000

Plastic mold designers and frequently faced with optimizing multi-quality issues in injection molded parts. These issues are usually in conflict with each other and thus tradeoff needs to be made to reach a final compromised solution. in this study an automated injection molding design methodology has been developed to optimize multi-quality characteristics of injection molded parts. The features of the proposed methodology are as follows : first utility theory is applied to transform the original multi-objective problem into single-objective problem. Second is an implementation of a direct search-based injection molding optimization procedure with automated consideration of robustness against process variation. The modified complex method is used as a general optimization tool in this study. The developed methodology was applied to an actual mold design and the results showed that the methodology was useful through the CAE simulation using a commercial injection molding software package. Applied to production this study will be of immense value to companies in reducing the product development time and enhancing the product quality.

• Journal of Welding and Joining
• /
• v.29 no.1
• /
• pp.46-51
• /
• 2011

TSV technology raises several reliability concerns particularly caused by thermally induced stress. In traditional package, the thermo-mechanical failure mostly occurs as a result of the damage in the solder joint. In TSV technology, however, the driving failure may be TSV interconnects. In this study, the thermomechanical reliability of TSV technology is investigated using finite element method. Thermal stress and thermal fatigue phenomenon caused by repetitive temperature cycling are analyzed, and possible failure locations are discussed. In particular, the effects of via size, via pitch and bonding pad on thermo-mechanical reliability are investigated. The plastic strain generally increases with via size increases. Therefore, expected thermal fatigue life also increase as the via size decreases. However, the small via shows the higher von Mises stress. This means that smaller vias are not always safe despite their longer life expectancy. Therefore careful design consideration of via size and pitch is required for reliability improvement. Also the bonding pad design is important for enhancing the reliability of TSV structure.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.18 no.2
• /
• pp.61-66
• /
• 2010

A virtual manufacturing system that is composed of JMatPro, a material modeler and $DEFORM^{TM}$-HT, a finite element package is applied to the hot press forming process: high temperature material properties for each phase such as flow stress, elastic modulus, Poisson's ratio, thermal expansion coefficient, in addition to TTT curve are predicted by JMatPro and taken into $DEFORM^{TM}$-HT to predict the material behavior considering phase transformation and heat transfer simultaneously. In order to verify the accuracy of computation, the residual stress and the springback were compared with the experimental measurements. Both the predicted and measured principal residual stresses and amount of springback were in good agreement. It was also found that the residual stresses generated from hot press forming are not negligible as it has been generally assumed, although the springback deformation is quite small.

• Journal of the Korean Society for Precision Engineering
• /
• v.20 no.12
• /
• pp.25-33
• /
• 2003

A burr has been defined as undesirable projection of material formed as a result of plastic flow from a cutting or shearing operation. It is unavoidable in all kinds of machining operation. As a result, burr makes troubles on manufacturing process due to deburring cost, quality of products and productivity. In this study, the primary interest is about exit burr. The burr formation mechanism in each type of burr is classified. Data bases are developed to predict burr formation result. In the milling operation, we develop an algorithm to analyze the burr formation mechanism by the geometrical analysis on the multi featured workpiece with multi cutting path. The algorithm includes three steps, i. e., the feature identification, the cutting condition identification, and the analysis on exit burr formation. We can predict which portion of workpiece would have the exit burr in advance so that we can manage to find a way to minimize the exit burr formation in an actual cutting. Also, this algorithm can be implemented in a commercial CAM package so that we can simulate the NC code to review the burr formation in advance.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.05c
• /
• pp.55-58
• /
• 2001

In this paper, we present the results of the design and fabrication of the VCO(Voltage controlled Oscillator) using RF circuit simulator GENESYS and electromagnetic field simulator EMpower Frequency range is fabricated VCO is 850 MHz ~ 950 MHz, which is used Colpitts Circuit. the fabricated VCO is consisted of resonator, oscillator and MSL(Microstrip Line) is used in LC tuning circuit.(operated by negative feedback) MSL(Microstrip Line), Varactor(Plastic package), low noise TR(SOT-23), chip inductor(1608), chip capacitor(1005), chip resistance(1005). 1005 type is used for sample fabrication of VCO. In the fabrication process, circuit pattern is screen printed on the alumina substrates of over 99.9% purity. Center frequency of the sample VCO is 850MHz at $V_T=1.5V$, while the simulated value was 1.0GHz at $V_T=1.5V$. Variable frequency range of the sample is 860~950MHz in contrast to the 1068~1100MHz of the simulated values.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.05c
• /
• pp.153-156
• /
• 2001

In this paper, we present the results of the design and fabrication of the VCO(Voltage controlled Oscillator) using RF circuit simulator GENESYS and electromagnetic field simulator EMpower Frequency range is fabricated VCO is 850 MHz ~ 950 MHz, which is used Colpitts Circuit. the fabricated VCO is consisted of resonator, oscillator and MSL(Microstrip Line) is used in LC tuning circuit.(operated by negative feedback) MSL(Microstrip Line), Varactor(Plastic package), low noise TR(SOT-23), chip inductor(1608), chip capacitor(1005), chip resistance(1005). 1005 type is used for sample fabrication of VCO. In the fabrication process, circuit pattern is screen printed on the alumina substrates of over 99.9% purity. Center frequency of the sample VCO is 850MHz at $V_T$=1.5V, while the simulated value was 1.0GHz at $V_T$=1.5V. Variable frequency range of the sample is 860~950MHz in contrast to the 1068~1100MHz of the simulated values.

• Food Science of Animal Resources
• /
• v.33 no.4
• /
• pp.448-455
• /
• 2013

Proper storage of left-over meat in a household refrigerator is important for extending its shelf-life and assuring its safety until it is next used. Various fresh meat packaging methods were examined to determine their effects on the quality characteristics of pork loins during household storage at $5^{\circ}C$. The packaging methods include 1) wrapping in a polyethylene pouch (WP), 2) keeping in an air-tight plastic container (CP), and 3) using a household vacuum packaging machine (VP). The fastest increase in total aerobic bacteria during storage occurred in the WP samples, followed by the CP and VP samples. The count of Pseudomonas spp. was found to be lowest in the VP, and then the CP and WP samples. Enterobacteriaceae grew fastest in the WP samples, followed by the CP and VP samples. The WP samples also incurred the most significant increase in thiobarbituric acids and volatile basic nitrogen values over the storage period, as compared to the CP and VP samples. Off-odour at 30 min after opening the package, was first notable at day 11 in WP samples, but only at day 15 in the CP and VP samples. The colour also deteriorated earlier in the WP samples than in the CP and VP samples.