• Korean journal of food and cookery science
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• v.10 no.3
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• pp.267-276
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• 1994

Recent epidemological observations suggested beneficial effects of dietary fiber on man's health. With the increased emphasis placed on the requirement for dietary fiber in the diet, there has been greater interest in successfully incorporating dietary fiber into food products. Hence, in this study, several dietary fibers such as cellulose, pectin, rice bran, barley bran and job's tears bran were incorporated into julpyun to determine their effects on some physical properties and sensory characteristics. Difference of water binding capacity(WBC) was found among dietary fiber sources. The WBC of pectin was highest and that of job's tears bran was lowest. The moisture contents of julpyun were increased as WBC of added dietary fiber sources was higher. In the rheometer measurement for julpyun added with dietary fiber, hardness of julpyuns added with cellulose and pectin was low. But, hardness of julpyun added cellulose was increased rapidly during storage at 4$^{\circ}C$. Springiness and gumminess wereshowed similar aspects to hardness. In the retrogradation speed by Avrami equation, the rate constant of julpyun added barley bran was low ao retrogradation occurred slowly. The results of sensory evaluation, julpyun added no dietary fiber showed good overall preference. Overall preference in sensory evaluation showed positive correlation with the after-swallowing and color.

• Journal of the Korean Society of Food Science and Nutrition
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• v.32 no.8
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• pp.1262-1269
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• 2003

In this study, enzymes were investigated as an antistaling agent for a Korean rice cake. Thermograms by a DSC demonstrated that the gelatinization-onset temperature of the Korean rice cake was at its lowest temperature of 71.1$^{\circ}C$ with the GP (glucoamylase+pullulanase) treatment, followed by $\beta$-amylase and $\alpha$-amylase. The gelatinization peak temperature of the Korean rice cake with enzyme treatment was relatively lower compared to the control. Furthermore, the Korean rice cake with GP treatment showed the lowest peak temperature. Melting enthalpy of the Korean rice cake increased with the enzyme treatment, with $\beta$-amylase, followed by $\alpha$-amylase and GP. Melting enthalpy of the Korean rice cake with GP treatment was significantly lower compared to the $\beta$- and $\alpha$-amylase treatment. Recrystallinity in the case of GP treatment was also significantly lower than control. The range of Avrami exponent (n) was 0.90 ∼ 1.20 and the time constant of retrogradation (1/k) of the Korean rice cake crystalline decreased in the following order: GP, $\beta$-, $\alpha$ -amylase and control. Textural characteristics of the Korean rice cake with enzyme treatment differed greatly from that of control. The L＊ values of all the Korean rice cakes made without $\beta$-amylase decreased and the a＊ values were significantly different at p<0.05. The GP treatment altered the b＊ value toward blue color, whereas $\beta$-and $\alpha$-amylase changed to the direction to yellow color. In sensory evaluation, the Korean rice cake with enzyme treatment showed higher evaluation compared to control.

• Food Engineering Progress
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• v.14 no.2
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• pp.146-152
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• 2010

A Korean traditional food, sulgidduk, was prepared with the supplementation of whole wheat flour (WWF) high in dietary fiber, and its quality characteristics were investigated depending on the WWF content (3, 5, and 7%). There was no significant difference found in moisture content of final products. Colorimetric analysis revealed that L-value representing brightness decreased with increasing WWF content. In texture profile analysis, freshly-made samples did not show measurable difference in hardness depending on WWF content. However, stored samples at 25$^{\circ}C$ for up to 3 days exhibited a decrease in hardness with increasing WWF content, indicating retardation of retrogradation related to WWF addition. Springiness and chewiness values showed decreasing trend with WWF content especially for stored samples. Retardation of retrogradation with WWF addition was also evidenced by observing the increment of time constant calculated from Avrami equation. Analysis of sensory evaluation demonstrated that considering flavor, taste, texture, and overall acceptability, 5% substitution of rice flour with WWF could be a promising formulation for quality product with high nutritional value.

• Journal of the Korean Magnetics Society
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• v.4 no.1
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• pp.12-19
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• 1994

The crystallization behavior of the amorphous $Fe_{73.5}Cu_{1}Nb_{3}Si_{16.5}B_{6}$ alloy with isothermal annealing at $552^{\circ}C$ was studied by $M\"{o}ssbauer$ spectroscopy. The amorphous phase was revealed to coexist together with $Do_{3}-FeSi$ nanocrystalline and Cu-duster in annealed alloys by $M\"{o}ssbauer$ spectrum analysis. At the early stage of crystallization, Si content of FeSi is high due to the creation of Cu-cluster, and decreases with annealing until 60 minutes, which results in the increase in the mean hyperfine field of FeSi, and thereafter keeps constant. After 60 minutes, the decrease in the mean hyperfine field of the residual armrphous, in spite of a slight change in the volume fraction of the FeSi and the residual armrphous, is caused by the increase in the content of Nb and B in residual amorphous phase. Both directions of the hyperfine field, those of the FeSi and the residual amorphous, become randomly oriented in about 60 minutes. For FeSi and Cu-duster, the Avrami exponents are 0.51 and O.65, the activation energies are 2.35 eV and 2.44 eV, and the incubation times are 2.4 minutes and 0.8 minutes respectively. Earlier formation of Cu-duster than that of FeSi is coincidence with the fact that Cu atom promotes the nucleation of the FeSi.

• Korean Journal of Materials Research
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• v.27 no.2
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• pp.63-68
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• 2017

A black nickel oxide powder, one of the commercial nickel oxide ores, was reduced by hydrogen gas in a batch-type fluidized-bed reactor in a temperature range of 350 to $500^{\circ}C$ and in a residence time range of 5 to 120 min. The hydrogen reduction behavior of the black nickel oxide was found to be somewhat different from that of green nickel oxide ore. For the black nickel oxide, the maximum temperature (below which nickel oxide particles can be reduced without any agglomeration) was significantly lower than that observed for the green nickel oxide. In addition, the best curve fittings of the Avrami model were obtained at higher values of the overall rate constant "k" and at lower values of the exponent "m", compared to those values for the green nickel oxide. It may be inferred from these results that the hydrogen reduction rate of the black nickel oxide is faster than that of the green nickel oxide in the early stages, but the situation reverses in the later stages. For the black nickel oxide ore, in spite of the low temperature sintering, it was possible to achieve a high degree fluidized-bed reduction at lower temperatures and at lower gas consumption rates than was possible for the green nickel oxide. In this regard, the use of black nickel oxide is expected to yield a benefit if its ore price is sufficiently lower than that of the green nickel oxide.

• Korean Journal of Materials Research
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• v.20 no.2
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• pp.72-77
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• 2010

Glass-ceramics were fabricated by heat-treatment of glass obtained by melting a coal bottom ash with $Li_2O$ addition. The main crystal grown in the glass-ceramics, containing 10 wt% $Li_2O$, was $\beta$-spodumene solid solution, while in $Li_2O$ 20 wt% specimen was mullite, identified using XRD. The activation energy and Avrami constant for crystallization were calculated and showed that bulk crystallization behavior will be predominant, and this expectation agreed with the microstructural observations. The crystal phase grown in $Li_2O$ 10 wt% glass-ceramics had a dendrite-like shaped whereas the shape was flake-like in the 20 wt% case. The thermal expansion coefficient of the $Li_2O$ 10 wt% glass-ceramics was lower than that of the glass having the same composition, owing to the formation of a $\beta$-spodumene phase. For example, the thermal expansion coefficient of $Li_2O$ 10 wt% glass-ceramics was $20\times10^{-7}$, which is enough for application in various heat-resistance fields. But above 20 wt% $Li_2O$, the thermal coefficient expansion of glass-ceramics, on the contrary, was higher than that of the same composition glass, due to formation of mullite.

• Korean Journal of Food Science and Technology
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• v.28 no.6
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• pp.1052-1058
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• 1996

The effect of varietal differences of rice starches by amylose content and gel consistency on the retrogradation behavior was studied. Setback viscosity of rice flour measured in a Brabender amylograph was significantly affected by amylose content as well as gel consistency. Increase in the rigidity modulus (E) of rice starch gels during storage determined by using texture analyzer indicated that amylose content was an important factor in terms of hardness increase. Kinetics of retrogradation showed that time constant of rice starch gels was influenced by amylose content, but not by gel consistency.

• Korean Journal of Materials Research
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• v.26 no.2
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• pp.79-83
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• 2016

A commercial NiO (green nickel oxide, 86 wt% Ni) powder was reduced using a batch-type fluidized-bed reactor in a temperature range of 500 to $600^{\circ}C$ and in a residence time range of 5 to 90 min. The reduction rate increased with increases in temperature; however, agglomeration and sintering (sticking) of Ni particles noticeably took place at high temperatures above $600^{\circ}C$. An increasing tendency toward sticking was also observed at long residence times. In order to reduce the oxygen content in the powder to a level below 1% without any sticking problems, which can lead to defluidization, proper temperature and residence time for a stable fluidized-bed operation should be established. In this study, these values were found to be $550^{\circ}C$ and 60 min, respectively. Another important condition is the specific gas consumption rate, i.e. the volume amount ($Nm^3$) of hydrogen gas used to reduce 1 ton of Green NiO ore. The optimum gas consumption rate was found to be $5,000Nm^3/ton$-NiO for the complete reduction. The Avrami model was applied to this study; experimental data are most closely fitted with an exponent (m) of $0.6{\pm}0.01$ and with an overall rate constant (k) in the range of 0.35~0.45, depending on the temperature.

• The Korean Journal of Food And Nutrition
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• v.29 no.6
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• pp.930-937
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• 2016

This study investigated the quality characteristics, antioxidant activities, and retarding retrogradation of sponge cakes made with 0%, 1%, 3%, 5% and 7% pumpkin (Cucurbita moschata Duch.) leaf powder. Specific capacity significantly increased with the addition (0.33~0.38), but baking loss and dough yield were not significantly different (p<0.05). In color, there was a decrease in the L-value, a-value and b-value, but ${\Delta}E$ increased in proportion to the amount of pumpkin leaf powder. Moisture content increased in the 0~3% additions, from 27.90~31.68%, but decreased in 5% and 7% (22.37% and 28.15%, respectively). pH tended to decrease significantly according to the amount of pumpkin leaf powder (p<0.05). Hardness increased with the addition of pumpkin leaf powder, and pumpkin leaf groups presented higher springiness and cohesiveness than the control. Chewiness was not significantly differ (p<0.05). In retarding retrogradation, Avrami exponent (n) showed that addition of 5% (0.1329) had more retarding retrogradation effect than the control (0.4319), whereas time constant (1/k) showed both 3% (100.00) and 5% (70.42) addition had more effect than control (18.45). Total phenols and flavonoids content increased proportionate to the addition levels. ABTS radical scavenging activity tended to increase according to the level of pumpkin leaf powder. In sensory properties, 5% addition showed maximum color, and 3% addition had the highest scores in flavor, moistness, sweetness, chewiness and overall acceptability. These results suggested that pumpkin leaf was a good addition to improve the quality characteristics, health and sensory preferences. The most appropriate proportion to have the effect of retarding retrogradation in sponge cake is 3%.

• Korean Journal of Food Science and Technology
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• v.21 no.6
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• pp.766-771
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• 1989

physicochemical properties of rice starch isolated from eight varieties were examined to evaluate the rice processing suitability The amylose contents of rice starch were varied with 16.7-29.7%, and IR 30, Godael, Aguja and Lengkwang varieties showed higher amylose content than the other varieties. The water binding capacity and blue value were in the range of 87.0 103.0 and 0.178-0.305, respectively. As the amylose content increased, the amylogram pasting temperature and the break down ratio increased, while the peak viscosity did not show any significant difference. The transmittance of 0.1% starch suspension slowly increased at $50^{\circ}C$ in the low-amylose content rice group, and rapidly increased at $65^{\circ}C$ in the high-amylose content rice group, but there were no differences above $75^{\circ}C$ among varieties. Also the low-amylose rice starch showed higher values in the swelling power and solubility. The hardness of the 30% rice starch gels was low in low-amylose one. During storage at $20^{\circ}C$ for 14 days, the increment of hardness was more slow in high-amylose one. The retrogradation velocity constant of rice starch gel by Avrami equation was the highest as 0.219 in Aguja variety.