• Korean Journal of Food Science and Technology
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• v.24 no.6
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• pp.541-546
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• 1992

In order to develop low salt fermented hen clam sauce with high stability, the effects of citric acid pretreatment and fermentation temperature were examined. The VBN contents of surf clam sauce treated with citric acid (SCA) were lower than those of control and the same sauces added alcohol at two temperature conditions ($5^{\circ}C$ and room temperature) during fermentation. The maximum $NH_2-N$ contents of control and SCA during fermentation at $5^{\circ}C$ were 501.3 and $618.4{\sim}691.6\;mg/100g$, respectively, and the pH of those showed $5.61{\sim}6.24$ and $2.43{\sim}3.21$. The total creatine contents of control and SCA, respectively, were $36.8{\sim}27.6\;mg/100g$ ranges. As the time of treatment with citric acid was longer, the degradation of ATP, ADP and AMP in the SCA was faster. In the control, the Ala content was $19.6{\sim}23.02%$ and was highest level among all free amino acids. As fermenting term was longer, among the free amino acids, Ala and Gly were large amounts in control and SCA, respectively, and Gly was slowly increased in SCA during fermentation. As the results of organoleptic test, the tastes of SCA showed good score than control.

• Structural Engineering and Mechanics
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• v.83 no.5
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• pp.693-707
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• 2022

Bonded joints have proven their performance against conventional joining processes such as welding, riveting and bolting. The single-lap joint is the most widely used to characterize adhesive joints in tensile-shear loadings. However, the high stress concentrations in the adhesive joint due to the non-linearity of the applied loads generate a bending moment in the joint, resulting in high stresses at the adhesive edges. Geometric optimization of the bonded joint to reduce this high stress concentration prompted various researchers to perform geometric modifications of the adhesive and adherends at their free edges. Modifying both edges of the adhesive (spew) and the adherends (bevel) has proven to be an effective solution to reduce stresses at both edges and improve stress transfer at the inner part of the adhesive layer. The majority of research aimed at improving the geometry of the plate and adhesive edges has not considered the effect of temperature and water absorption in evaluating the strength of the joint. The objective of this work is to analyze, by the finite element method, the stress distribution in an adhesive joint between two 2024-T3 aluminum plates. The effects of the adhesive fillet and adherend bevel on the bonded joint stresses were taken into account. On the other hand, degradation of the mechanical properties of the adhesive following its exposure to moisture and temperature was found. The results clearly showed that the modification of the edges of the adhesive and of the bonding agent have an important role in the durability of the bond. Although the modification of the adhesive and bonding edges significantly improves the joint strength, the simultaneous exposure of the joint to temperature and moisture generates high stress concentrations in the adhesive joint that, in most cases, can easily reach the failure point of the material even at low applied stresses.

• Journal of Welding and Joining
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• v.30 no.6
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• pp.113-119
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• 2012

Ultrasonic bonding is the novel packaging method for flip-chip with high yield and low-temperature bonding. The bonding module is a core part of the bonding machine, which can transfer the ultrasonic energy into the bonding spot. In this paper, we propose topology optimization technique which can make new design of boding modules due to the constraints on resonance frequency and mode shapes. The designed bonding module using topology optimization was fabricated in order to evaluate the bonding performance and reliable operation during the continuous bonding process. The actual production models based on the proposed design satisfied the target frequency range and ultrasonic power. The bonding test was performed using flip-chip with lead-free Sn-based bumps, the results confirmed that the bonding strength was sufficient with the designed bonding modules. Also the performance degradation of the bonding module was not observed after the 300-hour continuous process with bonding conditions.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.131-131
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• 2003

The advent of photonic technologies in the field of communications and data transmission has been heavily increasing the demand in integrated optical (IO) circuits capable of accomplishing not only simple tasks like signal, but also more sophisticated functions like all-optical signal routing or active multiplexing/demultiplexing. In the last decade, sol-gel technology has been widely used to prepare optical materials. Sol-gel processes show many promises for the development of low-loss, high-performance glass integrated optical circuits. However, crack formation is likely to occur during heat treatment in thick gel films. In order to overcome the critical thickness limitation, the organic-modified silicate has been widely used. In this case coating matrices have been prepared from the organo-silanes of T structures, acidic catalyst and the as-prepared gel films have been heat-treated below 200$^{\circ}C$ to avoid the crack formation and the degradation of organic components. However, the films prepared in the acidic condition and the low heat temperature make the films contain high OH groups which is the major optical loss function. In this work, C$\sub$6/H$\sub$5/SiO$\sub$1.5/ films were prepared on silicon substrate by sol-gel method using base catalyst in a PTMS/NH$_4$OH/H$_2$O/C$_2$H$\sub$5/OH system. The sol showed spinable viscosity at 50 wt% of solid content, and neglectable viscosity change with time. The films were crack-free and transparent after curing at 450 $^{\circ}C$, and highly condensed to minimize OH content in C$\sub$6/H$\sub$5/SiO$\sub$1.5/ networks. The effects of heat treatment of the films are characterized on the critical thickness, the chemical composition and the refractive indices by means of SEM, FT-IR, TGA, prism coupler, respectively.

• KSBB Journal
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• v.21 no.2
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• pp.157-163
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• 2006

A supercritical fluid process, called aerosol solvent extraction system(ASES), is especially suitable to the pharmaceutical, cosmetic and food industries due to its environmentally-friendly, non-toxic and residual solvent-free properties. In particular, the application of the ASES process to the processing of thermo-labile bioactive compounds has received attention of many scientists and engineers because of its low-temperature operating conditions. Unstable substances such as Vitamin-C and Vitamin-A can be effectively protected from degradation during the preparation process, because the ASES process is free from oxygen and moisture. In this study, Vitamin-C was formulated with 2-hydroxypropyl-${\beta}$-cyclodextrin (HP-${\beta$-CD) for enhancement of Vitamin-C stability and bioavailability using the ASES process. To investigate the influence of the preparation process on the stability of Vitamin-C, Vitamin-C/HP-${\beta}$-CD inclusion complexes were prepared using both conventional solvent evaporation method and ASES process, and stored in a 50 mM phosphate buffer solution of pH 7.0 at $25^{\circ}C$ for 24 hours. From the experimental results, the stability of the Vitamin-C/HP-${\beta}$-CD inclusion complex prepared from the ASES process was found to be much higher than that of pure Vitamin-C and the Vitamin-C/HP-${\beta}$-CD inclusion complex prepared by the solvent evaporation method. The stability of Vitamin-C was observed to increase with the decrease of temperature at a constant pressure or with the increase of pressure at a constant temperature.

• Korean Journal of Food Science and Technology
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• v.20 no.6
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• pp.883-889
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• 1988

The salted small shrimps(Acetes japonicus) were fermented for 3 months at room temperature. During the period of fermentation, the changes of shrimp protein properties were determined. The extractability of soluble protein was slightly decreased in 1 month fermentation, but thereafter increased. The contents of 10% TCA soluble fraction were gradually increased during 3 month fermentation, and the rate of 10% TCA soluble fraction/total soluble protein was also greatly increased during the period of fermentation. Sephadex G-100 gel filtration pattern was changed after 1 month fermentation, showing the disappearance of low molecular weight protein peaks, the decomposition and the delay of elution time of main shrimp protein peaks. Polyacrylamide gel disc electrophoresis patterns showed the degradation of main protein bands into lots of smaller bands after 1 month fermentation. The contents of total free amino acids were slightly decreased in 1 month fermentation and then gradually increased during the Period of fermentation. The rate of free amino acids/soluble protein was steadily increased during the period of fermentation, but the rate of free amino acids/10% TCA soluble fraction was decreased continually during the period of fermentation. The contents of most free amino acids were increased during the period of fermentation, but those of histidine and arginine were greatly decreased in 1 month fermentation. Ammonia was increased after 1 month fermentation. The pH value of salted shrimp was slowly changed during 3 months of fermentation, showing increase from 7.8 to 8.2.

• Journal of the Microelectronics and Packaging Society
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• v.12 no.3 s.36
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• pp.197-205
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• 2005

Development of the packaging is one of the critical issues for commercialization of the RF-MEMS devices. RF MEMS package should be designed to have small size, hermetic protection, good RF performance and high reliability. In addition, packaging should be conducted at sufficiently low temperature. In this paper, a low temperature hermetic wafer level packaging scheme for the RF-MEMS devices is presented. For hermetic sealing, Au-Sn eutectic bonding technology at the temperature below $300{\times}C$ is used. Au-Sn multilayer metallization with a square loop of $70{\mu}m$ in width is performed. The electrical feed-through is achieved by the vertical through-hole via filled with electroplated Cu. The size of the MEMS Package is $1mm\times1mm\times700{\mu}m$. By applying $O_2$ plasma ashing and fabrication process optimization, we can achieve the void-free structure within the bonding interface as well as via hole. The shear strength and hermeticity of the package satisfy the requirements of MIL-STD-883F. Any organic gases or contamination are not observed inside the package. The total insertion loss for the packaging is 0.075 dB at 2 GHz. Furthermore, the robustness of the package is demonstrated by observing no performance degradation and physical damage of the package after several reliability tests.

• Proceedings of the KWS Conference
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• 2002.10a
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• pp.450-455
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• 2002

Cu-cored Sn-Ag solder balls were fabricated by coating pure Sn and Ag on Cu balls. The melting behavior and the solderability of the BGA joint with the Ni/Au coated Cu pad were investigated and were compared with those of the commercial Sn-Ag and Sn-Ag-Cu balls. DSC analyses clarified the melting of Cu-cored solders to start at a rather low temperature, the eutectic temperature of Sn-Ag-Cu. It was ascribed to the diffusion of Cu and Ag into Sn plating during the heating process. After reflow soldering the microstructures of the solder and of the interfacial layer between the solder and the Cu pad were analyzed with SEM and EPMA. By EDX analysis, formation of a eutectic microstructure composing of $\beta$-Sn, Ag$_3$Sn, ad Cu$_{6}$Sn$_{5}$ phases was confirmed in the solder, and the η'-(Au, Co, Cu, Ni)$_{6}$Sn$_{5}$ reaction layer was found to form at the interface between the solder and the Cu pad. By conducting shear tests, it was found that the BGA joint using Cu-cored solder ball could prevent the degradation of joint strength during aging at 423K because of the slower growth me of η'-(Au, Co, Cu, Ni)$_{6}$Sn$_{5}$ reaction layer formed at the solder, pad interface. Furthermore, Cu-cored multi-component Sn-Ag-Bi balls were fabricated by sequentially coating the binary Sn-Ag and Sn-Bi solders on Cu balls. The reflow property of these solder balls was investigated. Melting of these solder balls was clarified to start at the almost same temperature as that of Sn-2Ag-0.75Cu-3Bi solder. A microstructure composing of (Sn), Ag$_3$Sn, Bi and Cu$_{6}$Sn$_{5}$ phases was found to form in the solder ball, and a reaction layer containing primarily η'-(Au, Co, Cu, Ni)$_{6}$Sn$_{5}$ was found at the interface with Ni/Au coated Cu pad after reflow soldering. By conducting shear test, it was found that the BGA joints using this Cu-core solder balls hardly degraded their joint shear strength during aging at 423K due to the slower growth rate of the η'-(Au, Cu, Ni)$_{6}$Sn$_{5}$ reaction layer at the solder/pad interface.he solder/pad interface.

• Journal of the Korean Academy of Esthetic Dentistry
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• v.22 no.1
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• pp.30-46
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• 2013

Porcelain fused to metal crown has been used mostly over the last 50 years for restorations in dentistry. However, the patients' awareness of aesthetic aspect, biocompatibility and the problems such as an allergy to metals led to the growing interest in the 'metal free restoration'. In particular, the price of the precious metals that have been mainly used to date has risen drastically, which made them impossible to play their role as oral restorative materials anymore, and in addition, the PFM restoration has intrinsic problems of chipping and fracture. Therefore, the CAD/CAM has been drawing more attention than ever due to the popular needs for the material that is more aesthetic and stronger for restoration of the molar implant. Considerations in carrying out the full zirconia restoration are as follows: 1) strength, 2) combination work, 3) light penetrability, 4) treatment of cracks, 5) the color reproducibility of the block, 6) the abrasivity of antagonistic tooth, 7) low temperature degradation. In this presentation, the color reproducibility of the block will be discussed. One of the biggest reasons for avoiding the full zirconia restoration is that it is difficult to reproduce the natural color compared to the conventional PFM restoration. Thus, many clinicians show reluctance due to the exposure of the ugly block when the coloring on the surface is removed after occlusal adjustment. From the experience of using blocks by Zirkonzahn for more than 4 years, it is considered that these problems can be addressed to some degrees. Accordingly, how to make restorations that are well in harmony with surrounding prosthesis or natural teeth will be discussed.

• Korean Journal of Microbiology
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• v.53 no.4
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• pp.273-285
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• 2017

The purpose of this study was to investigate the inhibitory effect of antibacterial substances produced by probiotic lactic acid bacteria (LAB) against biogenic amines-producing bacteria and the influence of culture conditions on the antibacterial activity of bacteriocin and organic acid. The bacteriocin solutions of Lactobacillus plantarum FIL20 (64 AU/ml) and Lactobacillus paracasei FIL31 (128 AU/ml) showed strong antibacterial activity against Serratia marcescens CIH09 and Aeromonas hydrophilia RIH28, respectively. And the lactic acid contents in the cell-free culture supernatants (CFCS) obtained from FIL20 and FIL31 strains were $107.3{\pm}2.7mM$ and $129.5{\pm}4.6mM$, respectively. Therefore, the bacteriocin solution (200 AU/ml) and the CFCS ($200{\mu}l/ml$) produced by L. plantarum FIL20 and L. paracasei FIL31 significantly (P < 0.05) decreased the bacterial numbers and histamine and tyramine production ability of S. marcescens CIH09 and A. hydrophilia RIH28. The amounts of histamine and tyramine produced by the CIH09 strain under conditions of low initial pH (5.0) and incubation temperature ($15^{\circ}C$) was significantly reduced by treatment with bacteriocin solution and CFCS obtained from L. plantarum FIL20. In addition, the bacterial counts and biogenic amines contents of CIH09 strain were significantly decreased (P < 0.05) when sodium chloride (5%) or potassium nitrite (200 mg/g) were mixed with the antibacterial substances of L. plantarum FIL20. Consequently, the bacteriocin and organic acid solution of L. plantarum FIL20 and L. paracasei FIL31 can be used as a biological preservation to effectively control the production of biogenic amines by the application of hurdle technology.