• Korean Journal of Food Science and Technology
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• v.26 no.1
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• pp.62-67
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• 1994

Quality change of Kimchi packaged with Ny/PE, Ny/CPP (PPtray+Ny/CPP cover), Cryovac BK-1, BK-4, and PET/Al/PE film was observed during storage at $5^{\circ}C$ (97%RH) and $20^{\circ}C$ (76%RH). To evaluate quality change of Kimchi, gas composition of package, pH, acidity, color, growth of lactic acid bacteria, and sensory score were measured periodically. Regarding to gas composition of package, Kimchi packaged with PET/Al/PE showed higher oxygen concentration at the beginning of storage than the others; carbon dioxide concentration was almost 100% at the end of storage. Carbon dioxide concentration of Kimchi packaged with Cryovac BK-1 and BK-4 which has higher gas permeability than the others, was increased to a maximum and then decreased due to permeation of gas during storage; oxygen concentration was increased. Unlike Kimchi packaged with Ny/PE, Ny/CPP, and PET/Al/PE, package swelling was not observed in Kimchi packaged with Cryovac BK-1 and BK-4 during storage. Although pH change was not significant depending on the packaging material, Kimchi packaged with Cryovac BK-1 and BK-4 showed lower pH value and higher acidity than those of the others. Color change of Kimchi was different depending on the packaging material during storage. Difference of the growth of lactic acid bacteria and sensory evaluation were not significant among Kimchi packaged with different packaging material during storage at either temperature. In conclusion, the effect of packaging materials on the quality change of Kimchi was not significant; however, to prevent from swelling of packaged Kimchi which is one of the most serious problem during storage and distribution, might be avoided by using relatively high $CO_2$ permeable film than high gas barrier film.

• Journal of the Microelectronics and Packaging Society
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• v.24 no.1
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• pp.83-90
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• 2017

In this paper, we evaluated the solderability of thin electroless nickel-electroless palladium-immersion gold (ENEPIG) plating layer for fine-pitch package applications. Firstly, the wetting behavior, interfacial reactions, and mechanical reliability of a Sn-3.0Ag-0.5Cu (SAC305) solder alloy on a thin ENEPIG coated substrate were evaluated. In the wetting test, maximum wetting force increased with increasing immersion time, and the wetting force remained a constant value after 5 s immersion time. In the initial soldering reaction, $(Cu,Ni)_6Sn_5$ intermetallic compound (IMC) and P-rich Ni layer formed at the SAC305/ENEPIG interface. After a prolonged reaction, the P-rich Ni layer was destroyed, and $(Cu,Ni)_3Sn$ IMC formed underneath the destroyed P-rich Ni layer. In the high-speed shear test, the percentage of brittle fracture increased with increasing shear speed.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.49 no.3
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• pp.227-231
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• 2004

A total of 219 polymerase chain reaction tests of genetically modified (GM) DNA sequences in soybean seeds and soybean sprouts were conducted during 2000-2001. No CM gene was found in 96 tests of soybean seeds. However, either a functional CP4EPSPS gene or the 355 promoter gene was found three times in 2000 and eight times in 2001, in between 0.01 and 0.17％ of soybean spout products, in 123 tests. Since the amount of GM genes was much less than the threshold limit of 3％, none of the 11 positive soybean-sprout samples needed to be libeled GM crops. Of these, seven sprout samples were from domestic seeds and four were from seeds imported from China. To find the contamination route, the raw materials, seed surface, floor of the storage room, area around the selection machine, surface of the packaging film and corn powder used in the package were tested. The 35S promoter gene was detected in only two samples of the corn powder (0.1％). Although we could not find the cause of the GM contamination, the sprout package film is one possibility. In total,8.9％ of the soybean sprout tests were GM positive, but the amounts were much less than the threshold of 3％. This means that there are frequent false-positives and these would threaten the sprout industry if GMO were decided qualitatively. Food companies should make their safety data available to the public and make an effort to address people's concerns about GM food more openly. In addition, there is a need to establish a quantitative test for GM genes in sampled water and a sampling method for raw materials.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.10
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• pp.3794-3801
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• 2010

This study evaluated the linear dimensional changes with the factor of time and thickness using of three commercially available tissue conditioners (Coe-Comport, Visco-Gel, Soft-Liner). The thickness of materials were changed (1.5mm, 3.0mm) and the percentage changes in dimension were measured at 1h(baseline), 12h, 24h, 3 days and 7days after specimen preparation. The obtained data were analyzed by ANOVA with the SAS/PC statistical package. From the results, large differences appear between the various tissue conditioners. The results suggested that the period recommended for forming functional impression would be 36h to 3days after insertion in the mouth. Depending on the type of tissue conditioner over time, as there were significant differences in the elastic change(p<0.05). Tissue conditioner of the 1.5mm, 3.0mm thickness were significantly different by the dimensional stability(p<0.05). Elastic deformation of the ideal itself, and resilient when compared only the look, Visco-Gel 3.0mm group, stability was the most stable volume. In addition, it is important to select tissue conditioners suitable for functional impression because of the wide range of dimensional stability among the materials.

• Korean Journal of Plant Resources
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• v.19 no.1
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• pp.59-67
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• 2006

This study was conducted to investigate the changes in some physicochemical properties, including pH, moisture and ash content, Ca, Na, Mg, K, crude saponin and codonoposide, of cultivated Codonopsis lanceolata, which were packed with woven polypropylene(WP) or low density polyethylene(LDPE, thickness 0.04 mm) bag and stored at $4^{\circ}C\;or\;20^{\circ}C$ for 30 days. pH of the juice of fresh Codonopsis lanceolata was 5.3 and decreased significantly during storage. Storage temperature exerted more influence upon the content of moisture and ash than package materials. The concentration of Ca, Mg, Na and K were 427.3mg, 203.4mg, 10.2mg, and 619mg per 100g dry matter respectively. The contents of Ca and Na were not changed significantly, but the contents of Mg and K were decreased during room temperature storage. It was revealed that the juices of stored sample had darkened and redness and yellowness were somewhat deeper than those of fresh sample. 1g of the cultivated Codonopsis lanceolata had 29.3mg of crude saponin and 3.78mg of codonoposide, and the changes of them during storage at various conditions were not significant.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.4
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• pp.503-509
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• 2019

The demand for smaller, faster, and multi-functional mobile devices in increasing at a rapidly increasing rate. In response to these trends, Stacked Chip Scale Package (SCSP) is used widely in the assembly industry. A film type adhesive called die attach film (DAF) is used widely for bonding chips in SCSP. The DAF requires high flowability at high die attachment temperatures for bonding chips on organic substrates, where the DAF needs to feel the gap depth, or for bonding the same sized dies, where the DAF needs to penetrate bonding wires. In this study, the mixture design of experiment (DOE) was performed for three raw materials to obtain the optimized DAF recipe for low elastic modulus at high temperature. Three components are acrylic polymer (SG-P3) and two solid epoxy resins (YD011 and YDCN500-1P) with different softening points. According to the DOE results, the elastic modulus at high temperature was influenced greatly by SG-P3. The elastic modulus at $100^{\circ}C$ decreased from 1.0 MPa to 0.2 MPa as the amount of SG-P3 was decreased by 20%. In contrast, the elastic modulus at room temperature was dominated by YD011, an epoxy with a higher softening point. The optimized DAF recipe showed approximately 98.4% pickup performance when a UV dicing tape was used. A DAF crack that occurred in curing was effectively suppressed through optimization of the cure accelerator amount and two-step cure schedule. The imizadole type accelerator showed better performance than the amine type accelerator.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.12
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• pp.261-267
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• 2020

The demand for faster, lighter, and thinner portable electronic devices has brought about a change in semiconductor packaging technology. In response, a stacked chip-scale package(SCSP) is used widely in the assembly industry. One of the key materials for SCSP is a die-attach film (DAF). Excellent flowability is needed for DAF for successful die attachment without voids. For DAF with high flowability, two-step curing is often required to reduce a cure crack, but one-step curing is needed to reduce the processing time. In this study, DAF composition was categorized into three groups: cure (epoxy resins), soft (rubbers), hard (phenoxy resin, silica) component. The effect of the composition on a cure crack was examined when one-step curing was applied. The die-attach void and flowability were also assessed. The cure crack decreased as the amount of hard components decreased. Die-attach voids also decreased as the amount of hard components decreased. Moreover, the decrease in cure component became important when the amount of hard component was small. The flowability was evaluated using high-temperature storage modulus and bleed-out. A decrease in the amount of hard components was critical for the low storage modulus at 100℃. An increase in cure component and a decrease in hard component were important for the high bleed-out at 120℃(BL-120).

• Journal of the Microelectronics and Packaging Society
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• v.30 no.2
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• pp.52-59
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• 2023

The effects of dielectric curing temperature and temperature/humidity treatment conditions on the interfacial adhesion energies between Ti diffusion barrier/polybenzoxazole (PBO) dielectric layers were systematically investigated for Cu redistribution layer applications of fan-out wafer level package. The initial interfacial adhesion energies were 16.63, 25.95, 16.58 J/m² for PBO curing temperatures at 175, 200, and 225 ℃, respectively. X-ray photoelectron spectroscopy analysis showed that there exists a good correlation between the interfacial adhesion energy and the C-O peak area fractions at PBO delaminated surfaces. And the interfacial adhesion energies of samples cured at 200 ℃ decreased to 3.99 J/m² after 500 h at 85 ℃/85 % relative humidity, possibly due to the weak boundary layer formation inside PBO near Ti/PBO interface.

• Korean Journal of Materials Research
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• v.12 no.9
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• pp.750-760
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• 2002

In this study, three solders, Sn-37Pb, Sn-3.5Ag, and Sn-3.8Ag-0.7Cu were screen printed on both electroless Ni/Au and OSP metal finished micro-via PCBs (Printed Circuit Boards). The interfacial reaction between PCB metal pad finish materials and solder materials, and its effects on the solder bump joint mechanical reliability were investigated. The lead free solders formed a large amount of intermetallic compounds (IMC) than Sn-37Pb on both electroless Ni/Au and OSP (Organic Solderabilty Preservatives) finished PCBs during solder reflows because of the higher Sn content and higher reflow temperature. For OSP finish, scallop-like $Cu_{6}$ /$Sn_{5}$ and planar $Cu_3$Sn intermetallic compounds (IMC) were formed, and fracture occurred 100% within the solder regardless of reflow numbers and solder materials. Bump shear strength of lead free solders showed higher value than that of Sn-37Pb solder, because lead free solders are usually harder than eutectic Sn-37Pb solder. For Ni/Au finish, polygonal shaped $Ni_3$$Sn_4$ IMC and P-rich Ni layer were formed, and a brittle fracture at the Ni-Sn IMC layer or the interface between Ni-Sn intermetallic and P-rich Ni layer was observed after several reflows. Therefore, bump shear strength values of the Ni/Au finish are relatively lower than those of OSP finish. Especially, spalled IMCs at Sn-3.5Ag interface was observed after several reflow times. And, for the Sn-3.8Ag-0.7Cu solder case, the ternary Sn-Ni-Cu IMCs were observed. As a result, it was found that OSP finished PCB was a better choice for solders on PCB in terms of flip chip mechanical reliability.

• Korean Journal of Materials Research
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• v.26 no.1
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• pp.22-28
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• 2016

In this study, we fabricated high quality color conversion component with green/red phosphor and low melting glass frit. The color conversion component was prepared by placing the green and red phosphor layer on slide glass via screen printing process. The properties of color conversion component could be controlled by changing coating sequence, layer thickness and heat treatment temperature. We discovered that optical properties of color conversion component were generally determined by the lowest layer. On the other hand, the heat treatment temperature also affected to correlated color temperature (CCT) and color rending index (CRI). The color conversion component with a green (lower) - red (upper) layer which was sintered at $550^{\circ}C$ showed the best optical properties: CCT, CRI and luminance efficacy were 3340 K, 78, and 56.5 lm/w, respectively.