• Journal of Applied Reliability
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• v.15 no.2
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• pp.90-100
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• 2015

Reliability growth rate (or reliability growth curve slope) have the two cases of trend as a constant or changing one during the reliability growth testing. The changing case is very common situation. The reasons of reliability growth rate changing are that the failures to follow the NHPP (None-Homogeneous Poisson Process), and the solutions implemented during test to break out other problems or not to take out all of the root cause permanently. If the changing were big, the "Goodness of Fit (GOF)" of reliability growth curve to test data would be very low and then reduce the accuracy of assessing result with test data. In this research, we are using Duane model and AMSAA model for assessing test data and projecting the reliability level of complex and repairable system as like construction equipment and vehicle. In case of no changing in reliability growth rate, it is reasonable for reliability engineer to implement the original Duane model (1964) and Crow-AMSAA model (1975) for the assessment and projection activity. However, in case of reliability growth rate changing, it is necessary to find the method to increase the "GOF" of reliability growth curves to test data. To increase GOF of reliability growth curves, it is necessary to find the proper parameter calculation method of interesting reliability growth models that are applicable to the situation of reliability growth rate changing. Since the Duane and AMSAA models have a characteristic to get more strong influence from the initial test (or failure) data than the latest one, the both models have a limitation to contain the latest test data information that is more important and better to assess test data in view of accuracy, especially when the reliability growth rate changing. The main objective of this research is to find the parameter calculation method to reflect the latest test data in the case of reliability growth rate changing. According to my experience in vehicle and construction equipment developments over 18 years, over the 90% in the total development cases are with such changing during the developing test. The objective of this research was to develop the newly assessing method and the process for GOF level increasing in case of reliability growth rate changing that would contribute to achieve more accurate assessing and projecting result. We also developed the new evaluation method for GOF that are applicable to the both models as Duane and AMSAA, so it is possible to compare it between models and check the effectiveness of new parameter calculation methods in any interesting situation. These research results can reduce the decision error for development process and business control with the accurately assessing and projecting result.

• International Journal of Precision Engineering and Manufacturing
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• v.3 no.2
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• pp.95-101
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• 2002

The propagation rate(da/dt) prediction parameter and the microstructure properties of creep crack in domestic 3.3NiCrMov steel were investigated at 550$\^{C}$ by using 0.5" CT specimen under constant load(4090N) and constant Ct(300∼4000N/mhr) condition that was maintained during crack growth of 1mm distance. C＊ usually increased with crack length though load was reduced in order to maintain constant Ct value as crack growth and considerably showed the scatter band, but Ct depended on load line displacement rate and represented a good relation with da/dt. At constant toad and Ct region, crack growth slope was 0.900 and 0.844 each, in the other hand C＊ slope was 0.480. Fully coalesced area(FCA) ahead of crack tip was increased as Ct value increase to the critical value, and after that value FCA decreased. The average diameter ditribution of cavity in FCA showed the greatest value about 1.5 ㎛ when Ct=2000N/mhr. The increasing of Ct in FCA view point enlarged the size of damage area and the size reached to maximum 800 ㎛ when Ct=2000N/mhr.

• Asian-Australasian Journal of Animal Sciences
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• v.16 no.6
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• pp.894-902
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• 2003

Prebiotics (peptides, N-acetyglucoamine, fructo-oligosaccharides, isomalto-oligosaccharides and galactooligosaccharides) were added to skim milk in order to improve the growth rate of contained Lactobacillus acidophilus, Lactobacillus casei, Bifidobacterium longum and Bifidobacterium bifidum. The purpose of this research was to study the potential synergy between probiotics and prebiotics when present in milk, and to apply modern optimization techniques to obtain optimal design and performance for the growth rate of the probiotics using a response surface-modeling technique. To carry out response surface modeling, the regression method was performed on experimental results to build mathematical models. The models were then formulated as an objective function in an optimization problem that was consequently optimized using a genetic algorithm and sequential quadratic programming approach to obtain the maximum growth rate of the probiotics. The results showed that the quadratic models appeared to have the most accurate response surface fit. Both SQP and GA were able to identify the optimal combination of prebiotics to stimulate the growth of probiotics in milk. Comparing both methods, SQP appeared to be more efficient than GA at such a task.

• KSBB Journal
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• v.13 no.3
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• pp.289-294
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• 1998

The effects of various step-fortifications of the initial medium with amino acids, glucose, and vitamines on the growth and metabolism of a hybridoma cell line in batch cultures were quantified. Comparisons between the metabolic rates of the various cultivations were made for the exponential growth phase. Fortification of the basal medium resulted in higher cell densities through a prolonged growth phase, but the maximum specific growth rate was not affected. The uptake rate of glutamine increased with the addition of amino acids but did not change upon the addition of glucose or vitamines. The specific glucose consumption decreased slightly with the addition of amino acids but increased production of lactate and {{{{ { NH}`_{4 } ^{ +} }}}}. A reciprocal relationship between the yields of {{{{ { NH}`_{4 } ^{+ } }}}} and lactate indicated a joint regulation of glycolysis and glutaminolysis.

• Food Science of Animal Resources
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• v.38 no.3
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• pp.442-450
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• 2018

Liquid egg products can be contaminated with Salmonella spp. during processing. A predictive model for the growth of Salmonella spp. in unpasteurized liquid eggs was developed and validated. Liquid whole egg, liquid yolk, and liquid egg white samples were prepared and inoculated with Salmonella mixture (approximately 3 Log CFU/mL) containing five serovars (S. Bareilly, S. Richmond, S. Typhimurium monophasic, S. Enteritidis, and S. Gallinarum). Salmonella growth data at isothermal temperatures (5, 10, 15, 20, 25, 30, 35, and $40^{\circ}C$) was collected by 960 h. The population of Salmonella in liquid whole egg and egg yolk increased at above $10^{\circ}C$, while Salmonella in egg white did not proliferate at all temperature. These results demonstrate that there is a difference in the growth of Salmonella depending on the types of liquid eggs (egg yolk, egg white, liquid whole egg) and storage temperature. To fit the growth data of Salmonella in liquid whole egg and egg yolk, Baranyi model was used as the primary model and the maximum growth rate and lag phase duration for each temperature were determined. A secondary model was developed with maximum growth rate as a function of temperature. The model performance measures, bias factor ($B_f$, 0.96-0.99) and $r^2$ (0.96-0.99) indicated good fit for both primary and secondary models. In conclusion, it is thought that the growth model can be used usefully to predict Salmonella spp. growth in various types of unpasteurized liquid eggs when those are exposed to various temperature and time conditions during the processing.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.15 no.4
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• pp.135-140
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• 2005

Thermal-fluid analysis was performed to understand the thermal behavior in the horizontal CVD reactor thereby to design a susceptor which has a uniform deposition rate during silicon EPI growing. Four different types of susceptor designs, standard (no hole susceptor), hole $\sharp$1 (240 mm), hole $\sharp$2 (150 mm) and hole $\sharp$3 (60 mm), were simulated by CFD (Computational Fluid Dynamics) tool. Temperature, gas flow, deposition rate and growth rate were calculated and analyzed. The degree of flatness of EPI wafer loaded on the susceptor was computed in terms of silicon growth rate. The simulation results show that the temperature and thermal distribution in the wafer are greatly dependent on inner diameter of hole susceptor and demonstrate that the introduction of hole in the susceptor can degrade wafer flatness. Maximum temperature difference appeared around holes. As the diameter of the hole decreases, flatness of the wafer becomes poor. Among the threes types of susceptors with the hole, optimal design which resulted a good uniform flatness ($5\%$) was obtained when using hole $\sharp$1.

• Membrane and Water Treatment
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• v.10 no.3
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• pp.191-199
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• 2019

In this study, we investigated the cultivation possibility using Hydrodictyon reticulatum in a continuous raceway pond as a tertiary sewage treatment plant. The cultivation possibility was evaluated by varying the light quantity, wavelength, and hydraulic retention time (HRT). Experimental results showed that the growth rates of algae and the removal efficiencies of nutrients increased as the light quantity increased, and the maximum photosynthetic rate was maintained at $100{\mu}mol/m^2{\cdot}s$ or higher. When wavelength was varied, nutrient removal efficiency and growth rate increased in the following order: green light, red light, white light, and blue light. The nutrient removal efficiencies and algae productivity in HRT 4 d were better than in HRT 8 d. We conclude that if Hydrodictyon reticulatum is cultivated in a raceway pond and used as a tertiary treatment facility in a sewage treatment plant, nutrients can be effectively removed, and production costs can be reduced.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.50 no.4
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• pp.247-255
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• 2005

ice yield and plant growth response to nitrogen (N) fertilizer may vary within a field, probably due to spatially variable soil conditions. An experiment designed for studying the response of rice yield to different rates of N in combination with variable soil conditions was carried out at a field where spatial variation in soil properties, plant growth, and yield across the field was documented from our previous studies for two years. The field with area of 6,600 m2 was divided into six strips running east-west so that variable soil conditions could be included in each strip. Each strip was subjected to different N application level (six levels from 0 to 165kg/ha), and schematically divided into 12 grids $(10m \times10m\;for\;each\;grid)$ for sampling and measurement of plant growth and rice grain yield. Most of plant growth parameters and rice yield showed high variations even at the same N fertilizer level due to the spatially variable soil condition. However, the maximum plant growth and yield response to N fertilizer rate that was analyzed using boundary line analysis followed the Mitcherlich equation (negative exponential function), approaching a maximum value with increasing N fertilizer rate. Assuming the obtainable maximum rice yield is constrained by a limiting soil property, the following model to predict rice grain yield was obtained: $Y=10765{1-0.4704^*EXP(-0.0117^*FN)}^*MIN(I-{clay},\;I_{om},\;I_{cec},\;I_{TN},\; I_{Si})$ where FN is N fertilizer rate (kg/ha), I is index for subscripted soil properties, and MIN is an operator for selecting the minimum value. The observed and predicted yield was well fitted to 1:1 line (Y=X) with determination coefficient of 0.564. As this result was obtained in a very limited condition and did not explain the yield variability so high, this result may not be applied to practical N management. However, this approach has potential for quantifying the grain yield response to N fertilizer rate under variable soil conditions and formulating the site-specific N prescription for the management of spatial yield variability in a field if sufficient data set is acquired for boundary line analysis.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.47 no.4
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• pp.311-318
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• 2002

Planting date of soybeans [Glycine max (L.) Merr.] is one of production components in cultural systems. The objective of the current study was to identify the components of soybean production and cultural practices encompassing planting dates and cultivars that respond to dry matter accumulation, harvest index and yield components. Three determinate soybean cultivars were planted on May 13 (early), June 3 (mid), and June 24 (late). Planting density was 60$\times$15cm with 2 seeds (222,000 plants per ha). Soybean plants were sampled every 10 days interval from the growth stages of V5 to R8 and separated into leaves including petioles, stems, pods, and seeds. Dry matter accumulations, harvest indices, and yield components were measured. Early planting had taken 55 days from VE to R2 and late planting taken 39 days indicating reduced vegetative growth. Early planting showed higher leaf, stem, pod and seed dry weights than late planting. However, late planting appeared to be higher harvest index and harvesting rate. Vegetative mass including leaf and stem increased to a maximum around R4/R5 and total dry weight increased to a maximum around R5/R6 and then declined slightly at R8. The highest seed yield was obtained with mid planting and no difference was found between early and late plantings. Cultivar differences were found among planting dates on growth characteristics and yield components. The results of this experiment indicated that soybean yield in relation to planting dates examined was mainly associated with harvest index and harvesting rate, and planting date of cultivars would be considered soybean plants to reach the growth stage of R4/R5 after mid August for adequate seed yield.

• KSBB Journal
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• v.26 no.3
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• pp.206-210
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• 2011

The growth effect of Nannochloropsis oculata (N.oculata), unicellular microalgae, by alginate was investigated. Alginate was depolymerized with sulfuric acid ($H_2SO_4$) and heat ($121^{\circ}C$), simultaneously. Addition of 0.75% alginate oligomer depolymerized with 0.2 N $H_2SO_4$ showed the maximum yield and the growth rate of N. oculata. Chlorophyll content and reducing sugar was increased by alginate oligomer in a dose-dependent manner. Alginate oligomer promoted the growth of N. oculata, whereas the original alginate polysaccharides had no significant effect. Laminaria japonica (L. japonica) extract containing high level of alginate was also increased growth rate and chlorophyll content. $CO_2$ supply addition to L. japonica extract showed no change the growth rate, although addition to alginate oligomer showed prominently increased. N. oculata could use more saccharides in presence of $CO_2$ according to reducing sugar determination. From these results, it is useful to establish optimal condition for high cell density cultivation of N. oculata.