• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.148-153
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• 2017

During natural ageing of HTPB propellant undergoes a series of slow physico-chemical degradation reactions. By using accelerated ageing conditions it is possible to simulate the material behaviour at different time-temperature conditions especially focused on the in-service conditions. Ageing behaviour of HTPB propellant were investigated using HFC(Micro-Heat Flow Calorimeter) is universal technique for measuring the rate of slow chemical and physical processes in long-term storage.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.5
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• pp.59-65
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• 2018

During natural aging, hydroxyl-terminated polybutadiene(HTPB) propellant undergoes a series of slow physico-chemical degradation reactions. By using accelerated ageing conditions it is possible to simulate the material behavior at different time-temperatures focusing on in-service conditions. Aging behaviors of HTPB propellant are investigated using HFC(heat flow calorimeter), a universal technique for measuring the rate of slow chemical and physical processes in long-term storage.

• Horticultural Science & Technology
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• v.32 no.2
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• pp.193-201
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• 2014

We investigated the effect of preharvest spray of aminoethoxyvinylglycine (AVG) on the fruit quality and incidence of physiological disorders during shelf-life of 'Hanareum' and 'Wonhwang' pear (Pyrus pyrifolia Nakai). AVG applications (0, 75, 150 and $300mg{\cdot}L^{-1}$) made 30 days before anticipated harvest of respective cultivar. AVG did not influence the fruit development and quality parameters including starch content, soluble solids and acidity at harvest time in two pear cultivars although the flesh firmness of the fruits treated with $300mg{\cdot}L^{-1}$ AVG were higher than that of control in 'Hanareum' pear. Among the three AVG concentrations, only $300mg{\cdot}L^{-1}$ AVG showed effectiveness on maintaining flesh firmness in 'Hanareum' pear during shelf-life. Meanwhile, competitive high flesh firmness was attained in 'Wonhwang' pear treated with $150mg{\cdot}L^{-1}$ AVG (27.7 N) and $300mg{\cdot}L^{-1}$ AVG (28.2 N) when compared with untreated control (17.8 N) during 21 days of shelf-life at $25^{\circ}C$. AVG did not cause any significant difference at skin color development relative to control in two pear cultivars. AVG decreased ethylene production and respiration rate at $300mg{\cdot}L^{-1}$ level in two pear cultivars during the entire shelf-life. During shelf-life, low incidence of physiological disorders including internal and core browning and mealiness were attained in the fruits treated at $300mg{\cdot}L^{-1}$ AVG in two cultivars when we compared with the untreated control.

• Korean Journal of Food Science and Technology
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• v.27 no.5
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• pp.703-707
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• 1995

Shelf-life dating of cooked and heat sterilized food was carried out with the use of principal component analysis (PCA). Changes in color, pH, acidity and sensory properties were measured and analyzed during storage at 20, 30 and $40^{\circ}C$. Acceptability of sample was decreased during storage, shelf-life of sample was determined 1.5, 3 and 3 months at 20, 30 and $40^{\circ}C$, respectively. Application of PCA to quality evaluation, principal component (PC) 1 dominated 49.6% of total variation and PC 2 expressed 28.8%. The rate of change of PC 1 to storage time was 1.3 with increasing temperature of $10^{\circ}C$, and close to shelf-life determined by accepability at 20 and $40^{\circ}C$. Therefore, PCA was applicable to evaluate the quality, predict the shelf-life and investigate the quality parameter of food during storage.

• Food Science and Preservation
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• v.15 no.3
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• pp.332-339
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• 2008

This study was performed to investigate the sorption characteristics and shelf-life of coated ascorbic acid Stability of ascorbic acid, which oxidizes easily during storage and processing, was achieved by applying a fluidized bed coating using Zein-DP and HPMC-FCC as covering materials. The monolayer moisture content calculated using the GAB equation showed a higher level of significance than when calculated using the BET equation. The fit to the isotherm curve was in the order of Halsey, Caurie, Oswin and Khun. The equilibrium relative humidity prediction model was established in terms of time and water activity, it had higher significance. The stability of the coated ascoribic acid during storage was investigated in terms of radical-scavenging activity, which decreased with increasing time of storage and was more affected at higher storage temperatures. The quality reduction rate constant (k) was calculated by a first-order reaction rate. The reaction rate constant increased with increasing storage temperature. The shelf-life of Zein-DP-coated ascorbic acid was estimated to be 45.83 days at 20C and 63.19 days at 10C, and the shelf-life for HPMC-FCC-coated ascorbic acid was estimated to be 28.84 days at 20C and 36.14 days at 10, the ascorbic acid was 24.52 days at $20^{\circ}C$ and 27.22 days at $10^{\circ}C$, respectively. Therefore, the fluidized bed coating effectively increased the stability of ascorbic acid.

• Asian-Australasian Journal of Animal Sciences
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• v.24 no.5
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• pp.713-722
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• 2011

The aim of this study was to confirm Pseudomonas spp. as the specific spoilage organism (SSO) of chilled beef during aerobic storage and to establish a model to predict the shelf life of beef. Naturally contaminated beef was stored at $4^{\circ}C$, and the spoilage limit of Pseudomonas organisms was determined by measuring several quality indicators during storage, including the number of Pseudomonas organisms, total number of bacteria, total volatile basic nitrogen (TVBN) values, L value color scale scores and sensory evaluation scores. The beef was then stored at 0, 4, 7, 10, 15 or $20^{\circ}C$ for varying amounts of time, and the number of Pseudomonas organisms were counted, allowing a corresponding growth model to be established. The results showed that the presence of Pseudomonas spp. was significantly correlated to each quality characteristic (p<0.01), demonstrating that Pseudomonas spp. are the SSO of chilled beef and that the spoilage limit was $10^{8.20}$ cfu/g. The Baranyi and Roberts equation can predict the growth of Pseudomonas spp. in beef, and the $R^2$ value of each model was greater than 0.95. The square root model was used as follows, and the absolute values of the residuals were less than ${0.05:\;{\mu_{max}}^{1/2}$ = 0.15604 [T+(-0.08472)] (p<0.01), $R^2$ = 0.98, $\lambda^{-1/2}$ = 0.0649+0.0242T (p<0.01, $R^2$ = 0.94). The model presented here describes the impact of different temperatures on the growth of Pseudomonas spp., thereby establishing a model for the prediction of the shelf life of beef stored between 0 to $20^{\circ}C$.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.28 no.3
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• pp.331-337
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• 1995

Seaweed Jellys(Muks) were prepared with sea mustard and sea tangle. Optimum storage condition was also investigated in terms of bacterial counts, pH, titratable acidity, gel strength and total volatile nitrogen(TVN) as soaking temperature and time in distilled water. Gel strength of Muk decreased, and TVN and baterial counts increased during storage in water. Seaweed Muk has a shelf life of 3 days at $32^{\circ}C$ in water and 15 days at $18^{\circ}C$. Shelf life of seaweed Muk with soy milk was 3 days at 18's and shorter than that of seaweed Muk without soy milk.

• Korean Journal of Food Science and Technology
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• v.26 no.3
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• pp.331-335
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• 1994

The shelf-life of instant noodle stored at $35{\sim}65^{\circ}C$ under dark condition was estimated from the change of hexanal content, which was linearly increased as the storage time increased. The rate constants of hexanal production at various storage temperatures followed Arrhenius relationship. The activation energy and $Q_{10}$ calculated were 12.7 kcal/mole and 1.92, respectively. The rancid flavor was organoleptically detected after 6 days at $65^{\circ}C$ and 13 days $50^{\circ}C$, at which the content of hexanal was 3.5 ppm. The shelf-life of instant noddle at $21^{\circ}C$ based on $Q_{10}$ value of hexanal production was about 110 days. The changes of acid value and peroxide value of instant noodle during storage followed similar pattern to those of hexanal. The activation energy and $Q_{10}$ for both acid value and peroxide value were 16.0 kcal/mole and 2.55, respectively. The hexanal content showed a high positive correlation with acid value as well as peroxide value at all storage temperatures.

• Korean journal of food and cookery science
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• v.25 no.2
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• pp.170-179
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• 2009

This study examined effects on shelf-life extension and prevention of starch retrogradation in rye-wheat mixed bread (RWMB) samples prepared with substitutions of 20, 40, 60, and 80% rye sourdough (RSD) as well as a control made with the addition of naturally fermented raisin extract. These effects were investigated using mold growth, water activity, and textural characteristics during a storage period of 8 days at $20^{\circ}C$. The activities of the rye sourdough were examined in terms of pH, total titratable acidity, general bacteria, lactic acid bacteria, and yeast counts. As the incubation time of the sour dough increased, pH decreased, while total titratable acidity increased. General bacteria, lactic acid bacteria, and yeast counts increased with increasing incubation time. Mold grew on the external surface of the control group after 6 days and on the surface of the RSD bread samples after 8 days, respectively. With regard to water activity, the control group had increasing activity as the storage period increased. In addition, the 20, 40, 60, and 80% RSD samples had increasing water activities until the 4th day however, these strongly decreased by the 6th day. In terms of textural characteristics, as the storage period increased, hardness increased, while springiness, cohesiveness, and resilience decreased. There were no significant differences in gumminess among the samples. The control, 20, 40, and 60% RSD samples had decreases in chewiness with increasing storage time, however, the 40% RSD sample did not differ significantly during the storage period. Finally, water activity was negatively correlated with hardness (p<0.05). In conclusion, the results indicate that substituting rye sourdough in rye-wheat mixed bread has a prolongation effect on shelf-life, but no effect on the prevention of starch retrogradation.

• Korean Journal of Agricultural Science
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• v.39 no.4
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• pp.503-509
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• 2012

This research aimed to investigate the effect of preharvest spray of aminoethoxyvinylglycine (AVG) on fruit quality of 'Nagasawa Hakuho' peach (Prunus persica Batsch). The efficacy of various concentrations of AVG (75 and 150 mg/L), which inhibits the ethylene biosynthesis, was evaluated under field conditions. Treatments were performed 21, 14 and 7 days before harvest, respectively. Fruit weight, flesh firmness, soluble solids content, acidity, ethylene production, respiration rate and skin color difference were determined at harvest time and during shelf-life at $25^{\circ}C$. Results indicated that the most appropriate timing of AVG spraying was 21 days before harvest at the concentration of 75 mg/L as shown higher firmness at harvest time and lower ethylene production and respiration rate during shelf-life. Spraying of AVG during near harvest period (14 to 7 days before harvest) inhibited fruit growth slightly, independent of concentration and did not affect fruit quality in 'Nagasawa Hakuho' peach.