• Journal of the Korean Society of Food Science and Nutrition
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• v.46 no.3
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• pp.335-342
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• 2017

In this study, we investigated the physicochemical quality characteristics and antioxidant activities of water extracts ($20^{\circ}C$ and $95^{\circ}C$) against different parts (leaf and petiole) from Wasabia japonica (wasabi). Water extracts were divided into six types of wasabi powders: leaf hot air dried (LD), petiole hot air dried (PD), whole (leaf+petiole) hot air dried (WD), leaf steamed and hot air dried (LSD), petiole steamed and hot air dried (PSD), and whole steamed and hot air dried (WSD). Turbidity was higher in wasabi $20^{\circ}C$ water extracts than in $95^{\circ}C$ hot water extracts. Browning degree was higher in wasabi leaf extracts than in petiole extracts. The pH of hot water extraction was lower than that of room temperature extraction. Wasabi extracts did not show much difference in Hunter's color values according to extraction temperature, expected that b value of yellowness was significantly higher in leaf extracts than in petiole extracts. Carbazole pectin contents of leaf extracts were significantly higher than in petiole extracts, however water soluble pectin was higher in petiole extracts. The total polyphenol contents of LD20 and LD95 were 1,561.43 mg gallic acid equivalent (GAE)/100 g and 1,163.02 mg GAE/100 g, respectively, and total polyphenols decreased during hot water extraction. Extracts from different parts of wasabi showed a significant difference in total flavonoid contents. Total flavonoid contents of LD20, LD95, PD20, and PD95 were 554.44 mg/100 g, 396.65 mg/100 g, 55.42 mg/100 g, and 47.68 mg/100 g, respectively. In the sensory evaluation, LD95 extract showed significantly higher values than other samples in terms of color, flavor, taste, mouth feeling, and overall acceptability. In the analysis of sourness, saltiness, umami, sweetness, and bitterness taste by an electronic tongue, the sourness values of LD20 and PSD95, saltiness values of WSD20 and WSD95, and umami values of PD20 and PD95 were significantly higher than other extracts. The results of this study suggest that wasabi leaf and petiole extracts enhance qualities and antioxidant activities when used different parts together.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.17 no.1
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• pp.6-10
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• 2007

The a-plane GaN layer on r-plane $Al_2O_3$ substrate is grown by mixed-source hydride vapor phase epitaxy (HVPE). The GaN/InGaN heterostructure is performed by selective area growth (SAG) method. The heterostructure consists of a flown over mixed-sourec are used as gallium (or indium) and nitrogen sources. The gas flow rates of HCl and $NH_3$ are maintained at 10 sccm and 500 sccm, respectively. The temperatures of GaN source zone is $650^{\circ}C$. In case of InGaN, the temperature of source zone is $900^{\circ}C$. The grown temperatures of GaN and InGaN layer are $820^{\circ}C\;and\;850^{\circ}C$, respectively. The EL (electroluminescence) peak of GaN/InGaN heterostructure is at nearly 460 nm and the FWHM (full width at half maximum) is 0.67 eV. These results are demonstrated that the heterostructure of III-nitrides on r-plane sapphire can be successfully grown by mixed-source HVPE with multi-sliding boat system.

• Korean Journal of Food Science and Technology
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• v.26 no.1
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• pp.37-43
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• 1994

Optimization study was conducted for preparation of uncompressed soy protein isolate(SPI) tofu in the aspects of water addition ratio, second heating temperature and amounts of oil and dextrin added. The SPI tofu was prepared without compression step with SPI-oil-dextrin mixture and $CaSO_4-GDL$ mixed coagulants. The data were statistically analyzed by multiple regresstion and response surface methodology(RSM). Addition of dextrin increased the hardness of tofu, particularly for the second heating at $85^{\circ}C$ and 8 times of water to SPI. RSM figure showed that the effect of dextrin on hardness became to be less as the heating temperature increased. The hardness increase effect was no significant except addition of 25% oil and 8 times of water and second heating at $85^{\circ}C$. The addition of 25% oil and $10{\sim}15%$ dextrin and second heating at $90^{\circ}C$ for $45{\sim}60$ minutes resulted hardness and cohesive tofu. The optimal method proposed for uncompressed SPI tofu on the basis of textural and sensory properties was first heating of homogenized SPI-oil-dextrin(100:25:15) with addition of 8 times of water(on the basis of SPI) at $100^{\circ}C$ for 6 minutes, cooling to $40^{\circ}C$, additon of mixed coagulants of $CaSO_{4}-GDL$(0.07 g, 0.0075 g/SPI) and second heating at $90^{\circ}C$ for 45 minutes.

• Journal of Conservation Science
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• v.26 no.1
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• pp.85-94
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• 2010

Color stable hydrogenated bisphenol-A (HBA) epoxy adhesives containing organic-inorganic hybrid nanocomposites were prepared and investigated the properties. Isophorone-diamine (IPDA) was used as a hardener and polyhedral organomeric silsesquioxanes (POSS; EP0408 and EP0409) having epoxy function groups were used to tailor adhesives in the nanoscale range. The dependence of the concentration of different nano materials were studied since the large surface area of the nanosized particles can cause significant changes in properties of adhesives. HBA-IPDA adhesives containing different amount of nanomaterials have been applied to the fresh Namsan granite and compared with those of commercial adhesives, which have problems of color change as well as a high viscosity. The mechanical properties of HBA-IPDA containing POSSs are consistent with those of commercial adhesives in addition to the low viscosity.

• Resources Recycling
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• v.9 no.1
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• pp.52-62
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• 2000

In order to maximize the recycling of converter slag to the more valuable fields, such as high quality aggregates for construction, cement industry and flux for ion making. It will be very important to control the compositions and properties of converter slag to suit the purpose of utilizastion. In this study, converter slag (STELCO, CANADA) was mixed with 5%~30% $SiO_2$and 7% carbon, and then reduced at $1650^{\circ}C$. After the reduction was completed, the reformed slags were cooled to room temperature in the furnace. All of the slags were then characterized using SEM-EDX, XRD and chemical analysis. Also the compressive strengths and densities of the reformed slags were measured to compare with natural aggregates. XRD analysis shows that th phases of reformed slags are changed from bredigite+merwinite mixed phases of 10% $SiO_2$added reduction to akermanite phases of 20% and 30% $SiO_2$ added reduction. But the SEM-EDX analysis revealed that the phase distribution of the reformed slags was changed very sensitively and complicately depends on the change of slag compositions. And also the properties of reformed slags are changed very much depend on the phase distribution. About one third of Cadmium and on fifth of Vanadium are remained in reduction reformed converter slag. Another heavy metal elements such as cobalt, zinc, lead are removed up to more than 90-95% of original slag. The compressive strength and density of 25% $SiO_2$ added and reformed slag is very near to natural granite. This is superior more than 10% to Thyssen's $SiO_2$ added and oxidized converter slag aggregates.

• Food Science and Preservation
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• v.15 no.2
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• pp.185-190
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• 2008

We investigated changes in fruit quality of Hallabong tangor (Citrus Kiyomi ${\times}$ ponkan) that was packaged with Si+CaO and LDPE film. The flesh ratio during storage was 74.33% (${\pm}3.66$) to 81.56% (${\pm}1.38$). Firmness of M16A, a variant of Hallabong tangor, was higher 100g-force than that of Hallabong tangor, changes of firmness was not shown among film packages. A fruit juice was $12-14^{\circ}$Brix, and this increased somewhat at the end of storage without film packaging. The titratable acidity of the M16A variety was 0.2% lower than that of the Hallabong tangor. Hallabong and M16A maintained freshness and taste for 120 and 60 days, respectively. The level of reducing sugars in the Hallabong tangor was 1% higher than that of the M16A variety. Reducing sugars increased at room temperature storage without film packaging. Total sugar content was 9.19% (${\pm}2.03$) to 12.78% (${\pm}0.75$). The content of vitamin C declined slowly after 105 days of storage. In conclusion, storage of Hallabong tangor with film packaging coated with Si+CaO was effective for maintaining freshness and quality.

• Korean Journal of Food Science and Technology
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• v.34 no.1
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• pp.79-84
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• 2002

Changes of microbiological and physicochemical characteristics of gamma irradiated Doenjang with low salt were studied. Samples were prepared by mixing the Doenjang and the Chungkukjang with 6% and 8% of salinity. The mixture was irradiated by gamma-ray with dose of 0, 5, 10, 20 kGy, and each sample was stored at $25^{\circ}C$ for 8 weeks. The results showed that the Bacillus cell was inactivated by $10^4-10^5\;cells/g$ with dose of 10 kGy, and yeast and Lactobacillus group were nearly eliminated by 10 kGy. The general quality of gamma irradiated low salt Doenjang, such as amino nitrogen, protease activity, and pH, were more stable than that of control during storage periods. The sensory evaluations showed that 8% (salt)-5 kGy and 6% (salt)-10 kGy irradiated samples were more acceptable than market purchased Doenjang. Therefore, it was considered that gamma irradiation was effective for maintaining better quality of low salt Doenjang and suitable radiation dose was 5 kGy in 8% salted, and 10 kGy in 6% salted sample.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.50 no.spc1
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• pp.88-93
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• 2005

The functional vice (Oryza sativa L.) has been highly regarded recently, in the change of rice maykets in the world. Goami2 (GA), one of the functional rice varieties, was developed from high-quality rice, Ilpumbyeo (IP). From the previous study, GA has been proved its beneficial effect on the improvement of metabolic control and body weight reduction especially in obesity, We could certain that GA was very difficult to be gelatinized due to the micro lump shown in the Scanning electron micrographs (SEM) photos. To improve its cooking quality, we investigated the changes of physicochemical properties, which were differentiated by the conditions of milling and blending. As GA was milled every $2\%$ until eliminating $12\%$, the nitrogen content was decreased linearly. But the decreasing rate of nitrogen content of GA during milling process was relatively lower than that of IP. Thus, we assumed that GA has relatively high nitrogen in inner starch of grain. The degree of milling had no effect on the gelatinization of cooked GA, but affected lightness and whiteness linearly, which were ranged in normal values when the rice was milled more than $10\%$ in weight. So we could concluded that the milling process was not proper to improve cooking quality of GA. And we could suggested that GA was needed to soak into water at least one hour before cooking by it water absorption rate at normal temperature$(21^{\circ}C)$ and sensory evaluation. From the texture analysis, cooked GA had higher hardness than other varieties. Therefore, we blended GA with IP, Baekjinju(BJ) and Hwasunchalbyeo(HS), then subjected to sensory evaluation. All evaluation items including the sensory preference were the highest scores for the rice blended with glutinous rice varieties, BJ and HS.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.24 no.2
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• pp.144-151
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• 1991

Quality stability and utilization of sardine protein concentrates were investigated. pH, water activity and amino-nitrogen contents of autoclaved and boiled products were little changed during the storage of 60 days. Available lysine contents of the both products at the initial stage of storage were 5.58g/16g-N and 5.69g/16g-N, respectively. But the available lysine contents and digestibility of the both products decreased slightly with increasing of storage time. Lipophilic and hydrophilic brown pigment formation of the both products increased during storage of 60 days, but peroxide value(POV) and thiobarbituric acid(TBA) value decreased. Total amino acid contents of the both products were in the range of $88.99{\~}89.90g/16g-N$, and the predominant ones were glutamic acid, aspartic acid, leucine and lysine. From the sensory scores of model snack, it is concluded that the sardine protein concentrate can be used as a source material for snack.

• Applied Chemistry for Engineering
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• v.21 no.3
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• pp.317-322
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• 2010

In this study, poly(methyl methacrylate) (PMMA) was treated with changing mixing ratios of $F_2$ and $O_2$ using oxyfluorination method for hydrophilic modification of PMMA film. For the characterizations of oxyfluorinated PMMA surface, contact angle, surface free energy, X-ray photoelectron spectroscopy (XPS) and optical transmittance (UV-vis) were carried out. After the oxyfluorination, PMMA surface became more hydrophilic showing the decrease of water contact angle from $69^{\circ}$ to $44^{\circ}$. So, surface free energy of oxyfluorinated PMMA film was increased from 46 to $58\;mN\;m^{-1}$. These results are attributed to hydrophilic functional groups such as hydroxyl group formed oxyfluorination method on the PMMA surface. From XPS results, it was confirmed that O/C concentration ratio on the surface of PMMA was increased, the amount of C-OH bonding which shows hydrophilicity was also largely increased from 6.7 to 24.8% with increasing fluorine partial-pressure via the oxyfluorination, The oxyfluorination conditions, room temperature, 1 bar with one mixture ratio of $F_2$ to $O_2$ had little influence on optical transmittance properties of PMMA film but enhanced its surface hydrophilicity. This result suggests that oxyfluorination method could be useful to change hydrophobic PMMA surface to hydrophilic.