• Journal of Welding and Joining
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• v.16 no.3
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• pp.148-156
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• 1998

The purpose of this study is to investigate the characteristics of Pb-Free Sn-2%Ag-Bi solder alloys. The solder alloys used in this study is Sn-2%Ag-(3,5,7,9%) Bi It is examined that their properties such as melting range, wettability, microstructure, microhardness, and tensile property. The addition of Bi(3,5,7,9%) lowered the melting point of the solder and the melting range was 196~203$^{\circ}C$. The wettability of the solder as equal to that of Sn-37% Pb solder. The morphology of structure did not change largely by addition of Bi. But the structure of cellular dendrite of linear type displayed. The tensile strength of the solder was superior to that of Sn-37%Pb solder. But the elongation was inferior to that of Sn-37%Pb solder. The hardness of Sn-2%Ag solder was tow times and that of Sn-2%Ag-Bi solder was three times of that in Sn-37%Pb solder. But the effect of increment of Bi content did not change largely.

• Journal of the Korea Institute of Building Construction
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• v.18 no.4
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• pp.321-327
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• 2018

Blast furnace slag has been actively used as a substitute for cement in the construction field with high value-added through resource recycling research. However, most of the slag cannot find a clear recycling purpose. This is because some slags contain unstable materials and are used for road-use asphalt and embankment, which are low value-added materials. Electric arc furnace reduction slag(ERS) has been reported to contain a large amount of unstable free CaO due to deoxidation and component adjustment. In this study, free CaO of ERS which is generated in Korean steelmakers is quantitatively evaluated by using ethylene glycol method. As a result of free CaO quantitative evaluation of ERS, it was confirmed that there is a big difference according to the location of each field. In addition, ERS generally existed in powder form as undifferentiated characteristics, but it was confirmed that free CaO content was different due to hydration product in aggregate form due to water treatment. In addition, free CaO is an amorphous material and its crystallization characteristics are different due to the influence of temperature when it is cooled. ERS requires a long-term aging period as it contains a lot of free CaO.

• Archives of Pharmacal Research
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• v.10 no.1
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• pp.29-35
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• 1987

The effect of drug addition on the bovine serum albumin (BSA)-edible dye complex was studied by spectrophotometric method. The edible dyes tested were amranth, erythrosine, tatrazine and sunset yellow. The moles of bound dye per protein mole and free energies for edible dyes bounded were determined at pH 7.4. The values of free energy change by the addition of drughs to BSA-edible dye were ranged fro -6, 260 to 08030 cal/mole. In the wide range of edible dye concentration (0.3-$7{\times}10^{-5}$$^{-5}$ M), acetylsalicylic acid (ASA) showed pattern of displacement different from that of dye. It was assumed that ASA has different binding mechanisms from edible dye.

• Environmental Analysis Health and Toxicology
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• v.11 no.1_2
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• pp.49-57
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• 1996

The production of reactive oxygen species on addition of hexavalent chromium (potassium dichromate, $K_2Cr_2O_7$ ) to lung cells in culture was studied using flow cytometer analysis. A Coulter Epics Profile flow cytometer was used to detect the formation of reactive oxygen species after $K_2Cr_2O_7$ was added to A549 cells grown to confluence. The cells were loaded with the dye, 2',7'-dichlorofluorescein diacetate, after which cellular esterases removed the acetate groups and the dye was trapped intracellularly. Reactive oxygen species oxidized the dye, with resultant fluorescence. Increased doses of Cr(VI) caused increasing fluorescence (10-fold higher than background at 200 gM). Addition of Cr(III) compounds, as the picolinate or chloride, caused no increased fluorescence. Electron paramagnetic resonance (EPR) spectroscopic studies indicated that three (as yet unidentified) spectral "signals" of the free radical type were formed on addition of 20, 50, 100 and 200 gM Cr(VI) to the A549 cells in suspension. Two other EPR 'signals" with the characteristics of Cr(V) entities were seen at field values lower than the standard free radical value. radical value.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.10
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• pp.1056-1060
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• 2004

In this study, 0.96B $i_{0.5}$($Na_{0.84}$ $K_{0.16}$)$_{0.5}$Ti $O_3$ + 0.04SrTi $O_3$ + 0.3 wt% N $b_2$ $O_{5}$+0.2 wt% L $a_2$ $O_3$ + xwt % Mn $O_2$ were investigated as a function of the amount of Mn $O_2$ addition in order to improve dielectric and piezoelectric properties of Lead-free piezoelectric ceramics. With increasing the amount of Mn $O_2$ addition, the density, electromechanical coupling factor( $k_{p}$), piezoelectric constant( $d_{33}$, $g_{33}$) and curie temperature (Tc) showed the maximum value of 5.7 g/㎤, 38 %, 219 pC/N, 26 mVㆍm/N and 32$0^{\circ}C$ at 0.1 wt% Mn $O_2$ addition, respectively, and mechanical quality factor( $Q_{m}$ ) showed the maximum value of 158 at 0.3 wt% Mn $O_2$ addition.ddition.ion.n.

• The Korean Journal of Food And Nutrition
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• v.28 no.3
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• pp.499-506
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• 2015

The aim of this study was to investigate the changes in the taste components of cheonggukjang made with germinated soybeans, which is produced by the addition of a smoking process. The total organic acid content of smoked cheonggukjang made with germinated soybeans (SCGS) was four times higher than that of non-smoked cheonggukjang made with non-germinated soybeans (NCNS). The total organic acid content of SCGS was lower than that of non-smoked cheonggukjang made with germinated soybeans (NCGS). The total free sugar content of NCGS and SCGS was approximately three times higher than that of NCNS. The total free amino acid content of NCGS was significantly decreased compared with that of NCNS, whereas the total free amino acid content of SCGS was 1.2 times higher than that of NCGS. The essential amino acid content of SCGS was significantly increased compared with that of NCGS. The ratio of glutamic acid to the total free amino acid in NCNS and SCGS was 19.6%. Similarly, the ratio of glutamic acid to the total free amino acid in NCGS was 19.1%. There were no significant differences in the total fatty acid content of NCNS, NCGS, and SCGS. The sensory evaluation of appearance, aroma, taste, and overall quality of SCGS was significantly increased compared with that of NCNS and NCGS. These results suggest that smoked cheonggukjang made with germinated soybeans could be utilized for the development of a novel fermented food.

• BMB Reports
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• v.32 no.1
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• pp.60-66
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• 1999

Matrix metalloproteinase-2 (MMP-2; 72-kDa gelatinase; 72-kDa type IV collagenase; gelatinase A) plays an important role in normal physiological processes and in many pathologic processes such as arthritis and metastasis of cancer. Tissue inhibitor of metalloproteinases-2 (TIMP-2) binds to proMMP-2 or mature MMP-2 at a 1:1 ratio and inhibits the catalytic activity of MMP-2. We demonstrated that the baculovirus/insect cell system does not have TIMP-2 activity. The human proMMP-2 free of TIMP-2 was expressed in the expression system and purified by one-step affinity chromatography using gelatin-Sepharose. The free proMMP-2 was autoactivated to the mature MMP-2 and autodegraded into smaller molecular weight forms in the absence of external activator. The activation and autodegradation of the proMMP-2 was much more rapid in the presence of 4-aminophenylmercuric acetate (APMA). Addition of TIMP-2 inhibits both APMA-induced activation and autodegradation of the free proMMP-2. However, an increasing concentration of TIMP-2 more readily inhibited activation of the free proMMP-2 than autodegradation. These results demonstrate that TIMP-2 plays roles in inhibition of both activation and autodegradation of the free proMMP-2 in addition to inhibition of the catalytic activity of MMP-2.

• Journal of Korean Medicine for Obesity Research
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• v.22 no.2
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• pp.115-124
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• 2022

Objectives: In this study, we investigated physicochemical characteristics and antioxidant activity of Artemisia argyi H. fermented with lactic acid bacteria. Methods: The A. argyi water extract was fermented using lactic acid bacteria isolated from kimchi at 30℃ for 96 h. To evaluate the physicochemical characteristics, we investigated pH, total acidity, viable cells, free sugars, free organic acids, and free amino acids contents during fermentation. In addition, we examined antioxidant activity of fermented Artemisia argyi H. by measurement of 2,2-diphenyl-1-(2,4,6-trinitrophenyl)-hydrazinyl (DPPH) and 2,2'-azubi-bus-3-ethylbenzothiazoline-6-sulfonic acid (ABTS⁺) scavenging activities. Results: During fermentation time, pH of fermented A. argyi was decreased from 4.57 to 3.22, and total acidity was increased from 0.39% to 1.63%. The number of lactic acid bacteria fermented A. argyi was increased from 1.28×10⁷ CFU/ml to 3.75×10⁸ CFU/ml during fermentation time. The free sugars of fermented A. argyi were confirmed glucose and sucrose. In addition, the organic acid content of fermented A. argyi was the highest in oxalic acid and lactic acid. In the composition of free amino acids, content of ornithine increased from 4.4 mg/100 g to 18.8 mg/100 g compared with non-fermented A. argyi. Furthermore, DPPH and ABTS⁺ radical scavenging activities of fermented A. argyi increased in a dose-dependent manner. Conclusions: In conclusion, our data suggest that lactic acid fermentation of A. argyi could be used as a functional food for antioxidants.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.582-589
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• 2006

Shear wane velocity is important property for grasping the dynamic characteristics of material. It is has been used in various fields such as non-destructive testings of structures, seismic analysis of geotechnical structures and maintenance of concrete structure, and etc. Usually, shear wave velocities of rock cores and concrete cylinders are determined by free-free resonance tests, Shear wave measurement in free-free resonance tests is not straightforward, as compared with rod wave and flexural wane measurements. In This study, a new technique using resonance features of flexural and shear waves were proposed in which the nodal points for the fundamental mode of flexural waves were employed to generate and measure the shear waves with the flexural waves minimized. The real measurements for aluminum cylinders proved validity and reliability of the proposed algorithm. In addition to the proposed algorithm, the effects of material properties on elastic-wave velocities in resonance measurements were also studied. In summary, a new framework of the resonance measurements for shear-wave velocity determination was established, based on the results of this thesis.

• Journal of Magnetics
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• v.2 no.3
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• pp.96-100
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• 1997

A spin valve structure of NiO(40 nm)/Co(2 nm)/Cu(2.6 nm)/Co(x nm)/Ta(5 nm) has been investigated for the application of magnetic random access memory (MRAM). The spin valve structure exhibited very large difference in the coercivities between pinned and free layers, a relatively high GMR ratio, and a low free layer coercivity. The spin valves were prepared by sputtering and were characterized by dc 4-point probe, and VSM. The spin valves with combined free layer exhibited a maximun GMR ratio of 10.4% with a free layer coercivity of about 82 Oe. The spin valves with a single 10 nm thick a-CoNbZr free layer exhibited a GMR ratio of about 4.3% with a free layer coercivity of about 12 Oe. The GMR ratio of the spin valves increased by addition of Co between Cu and a-CoNbZr. It has been confirmed that the coercivity of free layer can be decreased by increasing the thickness of a-CoNbZr. It has been confirmed that the coercivity of free layer can be decreased by increasing the thickness of a-CoNbZr layer without losing the GMR ratio substantially, which was mainly due to high resistivity of the amorphous "layers".