• Elastomers and Composites
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• v.40 no.2
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• pp.119-127
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• 2005

Material characteristics and lifetime evaluation are very important in design procedure to assure the safety and reliability of the rubber components. In this paper, the material test and accelerated heat aging test were carried out to predict the useful life of NBR and EPDM rubber mount for a compression motor which is used in a refrigerator. In order to investigate the effects of heat-aging on the material properties, crosslink density, modulus at 100% strain, stress-strain curves were obtained from uniaxial and equi-biaxial tensile tests. The change of compression set were used for assessment of the useful life and the time to threshold value were plotted against the reciprocal of absolute temperature to give the Arrhenius plot. The useful life at variable temperatures are obtained in the Arrhenius relationship.

• International Journal of Automotive Technology
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• v.7 no.6
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• pp.757-762
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• 2006

Reliability of automotive parts has been one of the most interesting fields in the automotive industry. Especially, a small DC motor was issued because of the increasing adoption for passengers' safety and convenience. For several years, small DC motors have been studied and some problems of a life test method were found out. The field condition was not considered enough in the old life test method. It also needed a lot of test time. For precise life estimation and accelerated life test, new life test procedure was developed based on measured field condition. The vibration condition on vehicle and latent force on fan motor shaft were measured and correlated with each other. We converted the acceleration data into the load data and calculated the equivalent load from integrated value. We found the relationship which can be used for accelerated life test without changing the severity by using different loading factors.

• Food Science of Animal Resources
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• v.42 no.2
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• pp.332-340
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• 2022

The objective of this study was to determine the optimal cooking time by considering the cooking loss, shear force, and off-odor reduction of pork large intestines. Commercial pork large intestines were purchased, quartered perpendicularly, and cooked in boiling water for 40, 120, 180, and 240 min. Cooking loss of the samples increased after 240 min of cooking (10.92, p<0.05) while shear force value was lower at 240 min (4.45) compared to that at other cooking times (p<0.001). The amount of major volatile organic compounds showed a decreasing trend with increasing cooking time. In particular, the amount of methyl pentanoate (17,528.71) and methyl isobutyrate (812.51), compounds with a relatively low odor threshold, decreased significantly after 120 min of cooking and no change was observed thereafter (p<0.05). In addition, the amount of 2-pentanol (3,785.65) and 1-propanol (622.26), possibly produced by lipid oxidation, significantly decreased at the same cooking time (p<0.001). In the principal component analysis, only the 40 min cooking time was significantly different from other cooking time by high amounts of 1-propanol, 2-pentanol, and methyl isobutyrate. In conclusion, in the present study, the optimal cooking time for pork large intestines was 120 min in terms of off-odor reduction, cooking loss, and shear force.

• Journal of Information Technology Applications and Management
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• v.27 no.3
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• pp.69-75
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• 2020

In this paper, we applied the shape parameters of the exponentialized exponential life distribution widely used in the field of software reliability, and compared the reliability properties of the software using the non-homogeneous Poisson process in finite failure. In addition, the average value function is also a non-decreasing form. In the case of the larger the shape parameter, the smaller the estimated error in predicting the predicted value in comparison with the true value, so it can be regarded as an efficient model in terms of relative accuracy. Also, in the larger the shape parameter, the larger the estimated value of the coefficient of determination, which can be regarded as an efficient model in terms of suitability. So. the larger the shape parameter model can be regarded as an efficient model in terms of goodness-of-fit. In the form of the reliability function, it gradually appears as a non-increasing pattern and the higher the shape parameter, the lower it is as the mission time elapses. Through this study, software operators can use the pattern of mean square error, mean value, and hazard function as a basic guideline for exploring software failures.

• Journal of the East Asian Society of Dietary Life
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• v.22 no.4
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• pp.489-496
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• 2012

This research investigated the quality characteristics and anthocyanin content of wet noodles according to the amount of freeze-dried purple sweet potato powder. For viscosity, initial pasting temperature tended to increase compared to the control group, whereas peak viscosity, peak viscosity time and final viscosity steadily decreased. As the amount of purple sweet potato powder increased, breakdown value of viscosity and set back value significantly decreased. For chromaticity, as the amount of purple sweet potato powder increased, L-value decreased gradually, whereas a-value gradually increased and b-value significantly decreased compared to the control group. Anthocyanin content significantly increased in the addidtive group (91.79) compared to the control group (70.20). Measurement of texture characteristics found that hardness was highest in the control group, but it decreased as the amount of purple sweet potato powder increased. Springiness, gumminess and chewiness were highest in the control group. In the sensory evaluation, color, odor, chewiness, and overall acceptance were high in the 6% addictive group. In this study, by investigating the anthocyanin contents, quality characteristics and sensory attributes of wet noodles with freeze-dried purple sweet potato powder, we found that the 6% additive group is the best. Our results provide basic information for the development of noodles with purple sweet potato powder.

• Journal of the East Asian Society of Dietary Life
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• v.17 no.6
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• pp.919-925
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• 2007

The purpose of this study was to investigate the influence of customers' perceived risks on their perception of value at family restaurants in Seoul. Frequency analysis, reliability analysis, factor analysis, multiple-regression analysis were employed to analyze the data. The customers' perceived risk were divided into 6 factors. Three of the perceived risk factors(financial, time, performance risk) negatively(-) influenced the perception of value. In particular, 'financial risk' was the most negative. However, 3 factors(physical risk, psychological risk, social risk) didn't have significant influence on perceived risk. As a result, customers of family restaurants appear to perceive various risks, and these risks have significant impacts on their perception of value. Therefore, food-service corporations need to reduce customers' perceived risks, possibly by various and efficient pricing-policies, discount, price-bundling, using coupon, effective physical evidence and offering unique compensation.

• International conference on construction engineering and project management
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• 2009.05a
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• pp.1528-1533
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• 2009

Infrastructure is provided to the user through long-term project period and large-scale working expenses. Existing facilities are getting old as time goes by. Accordingly, proper maintenance is required and generally more maintenance cost than initial invested cost is needed during life cycle. Therefore, a specific plan that just increases the value of facilities is required by evaluating performance of facilities and inputting minimum maintenance cost. Value engineering that increases the value of object by systemically analyzing Life Cycle Costs and function is actively promoted at the design phase of construction. These efforts can increase the performance of facilities at the maintenance phase of infrastructure. This study is to search how to evaluate the performance of Roadway by utilizing function analysis, as a core part of VE in the maintenance phase. In order to this a new evaluation criteria were proposed by adding an evaluation items to the existing criteria through the research of old documents, status of roadway maintenance and function analysis of VE. The results of this study may promote the effective performance evaluation to determine a resolution of roadway congestion in future. A succeeding study using the proposed evaluation criteria will be required.

• Journal of Practical Engineering Education
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• v.11 no.2
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• pp.291-303
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• 2019

The purpose of this research was to investigate the effect of the achievement goal orientation on college students' life satisfaction and sense of the belonging. This study used the analysis of the latent growth model to comprehend the slope of the 3 years longitudinal data. The result was that mastery approach and mastery avoidance affected the initial value of college life satisfaction, but not its slope as the time of 3 years went. On the other hand, performance approach was the opposite of mastery approach and mastery avoidance to college students' life satisfaction. Performance avoidance did not have an influence on both the initial value and the slope of college students' life satisfaction. The effect of the achievement goal orientation to the sense of belonging was also explored and its result was that mastery approach and mastery avoidance affected the initial value of the sense of belonging. However, it was different that performance approach did not influence the slope of the sense of belonging.

• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.505-505
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• 2009

The object is to optimize the best condition of organosolv pretreatment process with sulfuric acid as a catalyst. As a material, Pitch pine (Pinus rigida) was ground and sieved through 40-mesh screen, and Celluclast and $\beta$-glucosidase were used as enzymes for enzymatic hydrolysis. Pretreatment processes were carried out in the minibomb, and 20 g of materials with 200 ml of 50% ethanol solution (v/v) with 1% sulfuric acid as a catalyst. Pretreatment temperature was varied from $150^{\circ}C$ to $190^{\circ}C$, and time was varied from 0 to 20 min. Then, residual materials were used for enzymatic hydrolysis. The best conditions were selected by estimating followed enzymatic hydrolysis rate and degradable rates after pretreatment process. The highest value of enzymatic hydrolysis rate was obtained as 55 - 60% at 160 and at $180^{\circ}C$, but the value decreased under more severe conditions. As the residual rates decreased under severe conditions, it infered that the decrease of sugar contents limits enzymatic hydrolysis rates. Combined with enzymatic hydrolysis rate, degradable rates and H-factors, the temperatures at $160^{\circ}C$ for 20 min and at $180^{\circ}C$ for 0 min were concluded as the optimized conditions where have the lowest H-factor value for considering energy input.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.10a
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• pp.60-66
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• 2004

Hardness value decreased about 3% for annealed specimens and increased about 60% for one hour aged specimens. But the values of the other specimens aged two hours or more showed almost the same. The yield strength was the highest about 1,800㎫ in 0.06%Nb specimen having twice as much as the base meta1 specimen. Also, the elongation was the highest in 0.03%Nb specimen showing the same as base metal specimen. The higher aging temperature and the longer aging time, the higher fatigue life. On the other hand, the 0.03%Nb specimen showed the highest fatigue life which increased about 12% more than base metal specime. 0.06%Nb specimen aged at 482$^{\circ}C$ for 8 hours simultaneously satisfied the 250 grade strength and 200 grade elongation having the most superior mechanical properties.