• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.11
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• pp.1064-1073
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• 2013

In this paper, a compact 370 W high efficiency GaN(Gallium Nitride) HEMT(High Electron Mobility Transistor) power amplifier(PA) using internal harmonic manipulation circuits is presented for cellular and L-band. We employed a new circuit topology for simultaneous high efficiency matching at both fundamental and 2nd harmonic frequency. In order to minimize package size, new 41.8 mm GaN HEMT and two MOS(Metal Oxide Semiconductor) capacitors are internally matched and combined package size $10.16{\times}10.16{\times}1.5Tmm^3$ through package material changes and wire bonded in a new package to improve thermal resistance. When drain biased at 48 V, the developed GaN HEMT power amplifier has achieved over 80 % Drain Efficiency(DE) from 770~870 MHz and 75 % DE at 1,805~1,880 MHz with 370 W peak output power(Psat.). This is the state-of-the-art efficiency and output power of GaN HEMT power amplifier at cellular and L-band to the best of our knowledge.

• Archives of design research
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• v.17 no.3
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• pp.343-352
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• 2004

Under the production system of a free market economy, the modern consumers'goods that feature current trends reveal diverse aspects of the whole society and culture. This phenomenon is progressing at such a rapid speed that theories can barely keep up to explain it dearly. It is believed that the reason for the lag in academic theories is the formation of pluralistic values in human lifestyles due to the development of science and information communication. The pluralism of values in contemporary society is being studied in many academic fields, and the design among these fields often sees such a phenomenon as one of the post-modernism concepts, where post-modernism suggests a diversification and dismantling of modernism. In other words, the current design is closely watching products that are totally different from existing products, from complex and conceptual outcomes in the field of design to products that reflect various trends. Thus, it is true that package design, which proactively reflects current trends, freely traverses among specific domains of various fields that have been determined tacitly. It is also believed that other fields are also reflecting the same developments. Such a phenomenon is strikingly revealed with so-called 'fancy products', while other products 'parody' package design. This study sees the phenomenon as dismantling the border between product design and package design. The examined package design reflects the broader characteristics of the times, based on current concepts and meanings, after reviewing design examples.

• Journal of the Korean Society of Food Science and Nutrition
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• v.45 no.3
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• pp.402-408
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• 2016

Master packaging system consists of an inner individual package and secondary outer package. During the stages of chilled transport and distribution, the combination of primary individual package and secondary package was used to maintain a modified atmosphere for shiitake mushrooms. During the retail stage at higher temperature ($25^{\circ}C$), the primary individual package was exposed to display conditions after dismantling of the secondary packaging. The master packaging system was constructed to contain eight individual $30-{\mu}m$ thick polypropylene film bags of 500 g shiitake mushrooms inside a $40-{\mu}m$ low-density polyethylene bag. Carbon dioxide absorbent material [$Ca(OH)_2$] and/or moisture absorbent (superabsorbent polymer) were designed in their required amounts based on respiration characteristics and then applied to the outer secondary packaging in sachet form. Gas concentration of the packaging, temperature, and humidity were monitored throughout transport and storage. The quality of shiitake mushrooms was measured at the retail stage to determine the packaging effect. During the distribution stage of 108 h, $O_2$ and $CO_2$ concentrations in the master packaging system were maintained at 9~11% and 1~4% in the inner packaging, respectively, which are good for quality preservation. Compared to the control, the master packaging with $CO_2$ and/or moisture absorbents improved mushroom preservation and particularly reduced decay.

• Corrosion Science and Technology
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• v.6 no.6
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• pp.282-285
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• 2007

Smaller size and higher integration of electronic systems make narrower interconnect pitch not only in chip-level but also in package-level. Moreover electronic systems are required to operate in harsher conditions, that is, higher current / voltage, elevated temperature / humidity, and complex chemical contaminants. Under these severe circumstances, electronic components respond to applied voltages by electrochemically ionization of metals and conducting filament forms between anode and cathode across a nonmetallic medium. This phenomenon is called as the electrochemical migration. Many kinds of metal (Cu, Ag, SnPb, Sn etc) using in electronic packages are failed by ECM. Eutectic SnPb which is used in various electronic packaging structures, that is, printed circuit boards, plastic-encapsulated packages, organic display panels, and tape chip carriers, chip-on-films etc. And the material for soldering (eutectic SnPb) using in electronic package easily makes insulation failure by ECM. In real PCB system, not only metals but also many chemical species are included. And these chemical species act as resources of contamination. Model test systems were developed to characterize the migration phenomena without contamination effect. The serpentine-shape pattern was developed for analyzing relationship of applied voltage bias and failure lifetime by the temperature / humidity biased(THB) test.

• Journal of the Microelectronics and Packaging Society
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• v.10 no.3
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• pp.43-55
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• 2003

As the development of If industries and their electronic device manufacturing technology have been accelerated recently, the request for electronic devices with small size, light weight, and high performance has been inducing that electronic package and substrate (PCB) companies have to develop substrates with low cost, high dense I/O, excellent thermal properties and electrical properties. Therefore, world-wide chip makers have been setting their own severe reliability standards and requiring their suppliers to keep specification and to develop green, high frequency and high-performing substrates. Because properties of substrates are dependent mainly on their constituent materials, the application of them showing superior properties is expected to satisfy the customer's requirement. Therefore, substrate companies should ensure the superiority of materials and assure their competitive capability of substrates by analyzing the latest trends of technology and properties of the materials.

• Korean Journal of Food Science and Technology
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• v.41 no.3
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• pp.272-277
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• 2009

In this research, three dimensional mathematical models were developed to predict the shelf life of tofu packaged in a semi-rigid plastic container. A model combining oxygen transfer through the package and oxygen consumption within the package was considered. According to the results, the model simulations estimated that the number of microorganisms in the filled water was higher than that in the tofu, suggesting the shelf life of packaged tofu was not affected by the number of microorganisms in the tofu product, but rather by the number of organisms in the filled water. Additionally, the effects of the physical properties of the packaging material, such as oxygen permeability through the package, oxygen diffusion coefficient, the initial oxygen concentration in the filled water, and the depth of the filled water in the packaged tofu, were also observed.

• Journal of the Microelectronics and Packaging Society
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• v.25 no.4
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• pp.41-45
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• 2018

We have simulated the process induced warpage for panel level package using finite element method. Silicon chips of $5{\times}5mm^2$ were redistributed on $122.4{\times}93.6mm^2$ size panel and the total number of redistributed chips was 221. The warpage at each process step, for example, (1) EMC molding, (2) attachment of detach core, (3) heating, (4) removal of a carrier, and (5) cooling was simulated using ANSYS and the effects of detach core and carrier materials on the warpage were investigated. The warpage behaved complexly depending on the materials for the detach core and carrier. However, glass carrier showed the lower warpage than FR4 carrier regardless of detach core material, and the minimum warpage was observed when the glass was used for the detach core and carrier at the same time.

• Journal of the Microelectronics and Packaging Society
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• v.30 no.3
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• pp.35-39
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• 2023

ESG (Environment, Social, Governance) has become a major guideline for many companies to improve corporate value and enable sustainable management. Among them, the environment requires a technological approach. This is because technological solutions are needed to reduce or prevent environmental pollution and save energy. Semiconductor package technology has been developed to better satisfy the essential roles of semiconductor packaging: chip protection, electrical/mechanical connection, and heat dissipation. Accordingly, technologies have been developed to improve heat dissipation effect, improve electrical/mechanical properties, improve chip protection reliability, stacking and miniaturization, and reduce costs. Among them, heat dissipation technology increases thermal efficiency and reduces energy consumption for cooling. Also, technology to improve electrical characteristics has had an impact on the environment by reducing energy consumption. Technologies that recycling or reducing material consumption reduce environmental pollution. And technologies that replace environmentally harmful substances contribute to environmental improvement, in particular. In this paper, I summarize trends in semiconductor package technologies to prevent pollution and improve environment.

• Transactions of Materials Processing
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• v.21 no.7
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• pp.447-452
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• 2012

This paper is concerned with forming of Al-Zn-Mg-Sc aluminum alloy bolts, focusing on the effects of heat treatment and age-hardening on the formability and ductile damage evolution. Both experimental and finite element studies were performed. From the experiments, it is observed that the heat treatment or the normalization of Al-Zn-Mg-Sc aluminum alloy increases its formability dramatically resulting in successful bolt forming, while the effects of age-hardening at room temperature on the stress-strain relationship and formability are not very critical. Deformation characteristics such as distribution of effective stress and strain, material flow, and ductile damage evolution during bolt forming are examined using a commercial finite element package, Deform-2D. It should be noted that the extrusion load predicted by the finite element method matches well the experiment results. The finite element predictions on the deformation characteristics support the experimental observations such as fracture of bolt head flange, material flow, and distribution of hardness.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.191-191
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• 2009

In this paper, we have confirmed the temperature of LED chip and McPCB with thermal simulation program which is CFDedign V10 for analysis the thermal flow of HP LED package. we have known that the heat from LED chip is transferred through heat slug to copper layer of McPCB. the temperature of LED chip shows 85.11 [$^{\circ}C$], which shows the temperature gap of 7.52 [$^{\circ}C$] against McPCB. the gap of temperature affect reliability of the wire bonding and die attachment. therefore, copper layer of heat slug on the McPCB should designed with the largest dimension.