• Journal of the Microelectronics and Packaging Society
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• v.11 no.3 s.32
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• pp.37-45
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• 2004

Electroless Ni(P) has been widely used for under bump metallization (UBM) of flip chip and surface finish layer in microelectronic packaging because of its excellent solderability, corrosion resistance, uniformity, selective deposition without photo-lithography, and also good diffusion barrier. However, the brittle fracture at solder joints and the spatting of intermetallic compound (IMC) associated with electroless Ni(P) are critical issues for its successful applications. In the present study, the mechanism of IMC spatting and microstructure change of the Ni(P) film were investigated with varying P content in the Ni(P) film (4.6,9, and $13 wt.\%$P). A reaction between Sn penetrated through the channels among $Ni_3Sn_4$ IMCs and the P-rich layer ($Ni_3P$) of the Ni(P) film formed a $Ni_3SnP$ layer. Thickening of the $Ni_3SnP$ layer led to $Ni_3Sn_4$ spatting. After $Ni_3Sn_4$ spatting, the Ni(P) film directly contacted the molten solder and the $Ni_3P$ phase further transformed into a $Ni_2P$ phase. During the crystallization process, some cracks formed in the Ni(P) film to release tensile stress accumulated from volume shrinkage of the film.

• Journal of the Korean Ceramic Society
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• v.39 no.3
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• pp.259-264
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• 2002

In this study, sintering properties of Artificial Lightweight aggregates(ALAs) prepared from coal ash as a function of sintering temperature (900$^{\circ}$C, 1000$^{\circ}$C, 1100$^{\circ}$C) and time (2min, 5min, 10min) when limestone added as lightweight mineral was investigated. Increasing the sintering temperature resulted simultaneously from a decline of quartz mineral as well as growth of mullite mineral. Addition of limestone to ALAs newly formed sintered minerals such as clinoptilolite and plagioclase. Sintering effect of ALAs prepared from coal ash and limestone was more affected by a sintering temperature than time. As sintering temperature and time increae, transition of macropore to micropore and formation of closed pores were happened, consequently shrank the total pore volume of ALAs. The surface of ALAs sintered at 1000$^{\circ}$C for 5min was nearly not detected open pores due toe amalgamation effect of molten slag layer but homogeneous distributions of closed pores with micro-scale were examined in cross sectional area ALAs. Sintering temperature and time which present the most adequate state, in the preparation of ALAs, are corresponded to 1000$^{\circ}$C and 5min, respectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.4 s.119
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• pp.430-439
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• 2007

In this paper, we propose a broadband TEM horn antenna optimized using a genetic algorithm. The characteristics required for the TEM horn are the broad matching bandwidth from 2 GHz to 10 GHz and high gain in broadside with a small gain deviation within that bandwidth. In addition, a broadband balun is designed to improve the portability and to reduce the total size of the antenna. The measured return loss of the proposed TEM horn with the broadband balun is less than -10 dB(VSWR<2) from 2 GHz to 10 GHz. Compared to a conventional triangular type TEM horn, the proposed antenna shows about 80 % reduced volume and gives the broadside gain about 12 dBi with a gain deviation less than 6 dB from 2 GHz to 10 GHz. The time domain measurement shows less than 0.4 ns group delay and the pulse measurement using the transmitting signal with the rising time of 58.5 ps shows the received pulse with the rising time of 66.5 ps, which is less than 10 % rising time variation.

• KSBB Journal
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• v.10 no.1
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• pp.78-88
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• 1995

The encapsulatpd A. niger grew up inside the capsule and mycelia penetrated through the pore of the capsule membrane. The mycelia on the capsule wall became loose when the carbon source and oxygen were deficient in the medium. On the contrary, the production rate increased and mycelia made a lump tightly when the carbon source and oxygen were sufficient. Namely, number of proper capsule of unit volume in the medium was existed. The phenomenon which was swelled of capsule membrane in cultivation could prevented by adding CaCl2 into the medium. According to the time adding CaCl2 into the medium, the production rate of citric acid was influenced. In case of adding CaCl2 into the medium at 7th day cultivation, the production yield of citric acid was increased about 40 percent higher than that of adding CaCl2 initially. The production yield of citric acid using encapsulated A. niger of flask culture was influenced with oxygen supply. The production yield of citric acid ($\Delta$p/$\Delta$s) of the flask culture was increased 3.88 time by using T-flask instead of parafilm sealed flask. Therefore, the productivity and consumption rate concerning production which was taken carbon source were increased when oxygen supply was sufficient. The production of citric acid using encapsulated A. niger was increased average 30 percent higher than that of bead in between 6th and 13th day cultivation.

• Korean Journal of Environmental Agriculture
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• v.33 no.4
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• pp.372-380
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• 2014

BACKGROUND: This study was carried out in order to closely examine the influence of fertilization upon growth in container of seedling in indeciduous Quercus species (Q. mysinaefolia, Q. acuta and Q. glauca). METHODS AND RESULTS: Fertilizer level was made by adjusting water soluble compound fertilizer (N:P:K=19: 19:19, v/v) to 1000, 2000, $3000mg{\cdot}L^{-1}$ level along with non-fertilizing plot. Fertilization increased height, root collar diameter growth, and dry weight in these three species of trees. The more increase in fertilizer level led to the more rise even in growth of these species. H/D ratio and T/R ratio also showed tendency of getting bigger in the more rise in fertilizer level. Photosynthetic rate was shown to get higher in the higher fertilizer level according to fertilization in all the three species. In the analysis of root morphological traits, the total root length was surveyed to be longer in the more rise in fertilizer concentration. As even a case of root project area, surface area, and root volume is the similar tendency to characteristics in the total root length, a rise depending on fertilization was observed. CONCLUSION: In light of the results in this experiment, the fertilizer level is judged to be $2000mg{\cdot}L^{-1}$ level that is proper for production of 1-year-old container seedling in indeciduous Quercus species with excellent root development and high seedling quality index.

• Economic and Environmental Geology
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• v.36 no.3
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• pp.149-157
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• 2003

Deep sea core samples were taken in the southwestern part of the Ulleung Basin in order to characterize the properties of shallow gases in the sediment. Amount of shallow gases in the sediments were calculated by head space techniques, and chemical and isotopic compositions of hydrocarbon gases were analyzed. Geochemical analyses were carried out on the gas bearing sediments to find out relationship between natural gas contents and organic characteristics of the sediments. Seismic characteristics of shallow gases in the sediments were also examined in this study. The amount of the hydrocarbon gases in the sediments range from 0.01% to 11.25%. Calculation of volume of gas per volume of wet sediment varies from 0.1 to 82.0 ml HC/L wet sediment. Methane consists 98% of the total hydrocarbon gases except for two samples. Based on the methane content and isotopic composition$(\delta^{13}c)$: -94.31$\textperthousand$~-55.5$\textperthousand$), the hydrocarbon gases from the sediments are generated from bacterial activities of methanogenic microbes. Contents of hydrocarbon gases are variable from site to site. Volume of shallow gases in the sediments shows no apparent trends vs. either characteristics of organic matter or particle sizes of the sediments. Gas concentration is high in the area of seismic anomalies such as blanking zone or chimney structures in the section. Physicochemically the pore water and the formation water systems are saturated with gases in these areas. Concentration of hydrocarbon gases in the sediments in these area shows favorable condition for generation of gas hydrate, as far as the other conditions are satisfied.

• Archives of design research
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• v.17 no.2
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• pp.351-362
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• 2004

Generally, they respond to a phenomenon, with their any way, which they have looked at in their surroundings, and also put into their action successively and variously according as what it is. A person who has not so much problems in experiential education added to mental and physical ability prefers controlling his manner by himself as seeing, listening and feeling to being cured it by other physical support. Meanwhile, even though there are tools that we use conveniently in everyday life, it is sometimes required that user is able to control his action by himself with a certain interactive function to deal with a accidental situation. For example, in the home, when they were cooking, washing dishes and taking a bath they would not often control their minds on how to act about flowing water through the faucet going back and forth between saving and easygoing. By reasons of those statements, the project has been studied to propose the new conceptual faucet which digital technology is applied to, for recognizing the volume of water flowed through water pipe as counting it with built-in flow meter, and then saving water as controling the water-flow with faucet lever. It means that homemakers can observe the flow rate of water from the faucet placed in front of the sink in kitchen and control it right away for saving water. For studying this project, the kinds and features of the various flow-meters that measure the volume of water-flow were researched and analyzed for taking a reasonable type to the new ideal faucet. According to this analyzing, turbine-flow-meter was selected as appropriate form for the digital display-built-in faucet that would be presented in this project. As the next step, the basic structure was created for developing a new conceptual faucet. Finally two models have been presented through several steps for making the suitable shape to the new style faucet.

• Korean Journal of Food Science and Technology
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• v.42 no.3
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• pp.310-316
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• 2010

The objective of this study was to determine the optimum manufacturing conditions of whole egg powder with high foaming property sufficient for making sponge cakes. Whole eggs were either desugarized and/or adjusted pH before spray-dried at a temperature of $70^{\circ}C$. The physical properties of the cake were measured, and sensory evaluation was conducted on a 9-point scale. The pH and specific gravities of the foam and batter made from desugarized egg powder did not differ from those of the control, whereas batter made from commercial powder experienced significant loss of cake characteristics. The pH adjustment did not improve the foaming properties of the egg powders. The volume and textural properties of the cakes made from spray-dried egg did not differ from those of fresh egg. The taste and sensory characteristic scores for fresh egg, desugarized whole egg powder, and commercial powder were 5.00, 4.78, and 1.89, respectively. These results indicate that egg powders desugarized and spray-dried at $70^{\circ}C$ are sufficient for making sponge cakes with acceptable physical and sensory attributes.

• Korean Journal of Food Science and Technology
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• v.52 no.5
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• pp.546-554
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• 2020

Natural food additives have recently attracted attention as alternatives to synthetic additives. However, little information is available regarding their potential toxicity. In this study, we evaluated ten different natural food additives that are widely used in commercial foods in South Korea based on their actual usage level and daily intake. The results showed that none of the tested natural additives exhibited cytotoxicity in terms of inhibition of cell proliferation/viability and lactate dehydrogenase leakage. Additionally, the tested natural food additives did not generate intracellular reactive oxygen species (ROS), whereas they significantly decreased intracellular ROS levels produced by hydrogen peroxide. Moreover, none of the tested natural additives affected cell proliferation and viability in 2D and 3D intestinal epithelium models. Taken together, the ten natural food additives did not exhibit cytotoxicity in their actual usage levels. These findings can be used to further assess the toxicity of natural food additives.

• Applied Chemistry for Engineering
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• v.26 no.2
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• pp.217-223
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• 2015

Effects of the post-acid treatment of SAPO-34 sample by hydrochloric acid were investigated to enhance the catalytic performance in DTO reaction. Uniformly sized SAPO-34 samples with cubic-like morphology were prepared by hydrothermal method using TEAOH and DEA as the structure directing agents. It was modified in terms of the HCl concentration and treating time. As a result, the total surface area and micropore volume for the well modified samples increased and the total acid site was somewhat decreased along with the erosion of the external surface. Especially, the catalytic lifetime and light olefins selectivity for acid treated SAPO-0.2 M (3 h) samples were considerably enhanced compared with those of untreated SAPO-34 samples. It indicates that the deactivation by coke formation proceeds mainly at the pore entrance on the external surface. Therefore, the acid treatment was confirmed to be a simple method which can significantly improve the catalytic performance by modifying the external surface of SAPO-34 catalyst.