• Asian-Australasian Journal of Animal Sciences
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• 제27권7호
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• pp.1013-1018
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• 2014

In this study, we developed kinetic models to predict the growth of pathogenic Escherichia coli on cheeses during storage at constant and changing temperatures. A five-strain mixture of pathogenic E. coli was inoculated onto natural cheeses (Brie and Camembert) and processed cheeses (sliced Mozzarella and sliced Cheddar) at 3 to 4 log CFU/g. The inoculated cheeses were stored at 4, 10, 15, 25, and $30^{\circ}C$ for 1 to 320 h, with a different storage time being used for each temperature. Total bacteria and E. coli cells were enumerated on tryptic soy agar and MacConkey sorbitol agar, respectively. E. coli growth data were fitted to the Baranyi model to calculate the maximum specific growth rate (${\mu}_{max}$; log CFU/g/h), lag phase duration (LPD; h), lower asymptote (log CFU/g), and upper asymptote (log CFU/g). The kinetic parameters were then analyzed as a function of storage temperature, using the square root model, polynomial equation, and linear equation. A dynamic model was also developed for varying temperature. The model performance was evaluated against observed data, and the root mean square error (RMSE) was calculated. At $4^{\circ}C$, E. coli cell growth was not observed on any cheese. However, E. coli growth was observed at $10{\circ}C$ to $30^{\circ}C$C with a ${\mu}_{max}$ of 0.01 to 1.03 log CFU/g/h, depending on the cheese. The ${\mu}_{max}$ values increased as temperature increased, while LPD values decreased, and ${\mu}_{max}$ and LPD values were different among the four types of cheese. The developed models showed adequate performance (RMSE = 0.176-0.337), indicating that these models should be useful for describing the growth kinetics of E. coli on various cheeses.

• Structural Engineering and Mechanics
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• 제81권5호
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• pp.565-574
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• 2022

The infrastructures such as offshore, bridges, power plant, oil and gas piping and aircraft operate in a harsh environment during their service life. Structural integrity of engineering components used in these industries is paramount for the reliability and economics of operation. Two regression models based on the concept of Gaussian process regression (GPR) and Minimax probability machine regression (MPMR) were developed to predict stress intensity factor range (𝚫K). Both GPR and MPMR are in the frame work of probability distribution. Models were developed by using the fatigue crack growth data in MATLAB by appropriately modifying the tools. Fatigue crack growth experiments were carried out on Eccentrically-loaded Single Edge notch Tension (ESE(T)) specimens made of API 5L X65 Grade steel in inert and corrosive environments (2.0% and 3.5% NaCl). The experiments were carried out under constant amplitude cyclic loading with a stress ratio of 0.1 and 5.0 Hz frequency (inert environment), 0.5 Hz frequency (corrosive environment). Crack growth rate (da/dN) and stress intensity factor range (𝚫K) values were evaluated at incremental values of loading cycle and crack length. About 70 to 75% of the data has been used for training and the remaining for validation of the models. It is observed that the predicted SIF range is in good agreement with the corresponding experimental observations. Further, the performance of the models was assessed with several statistical parameters, namely, Root Mean Square Error (RMSE), Mean Absolute Error (MAE), Coefficient of Efficiency (E), Root Mean Square Error to Observation's Standard Deviation Ratio (RSR), Normalized Mean Bias Error (NMBE), Performance Index (ρ) and Variance Account Factor (VAF).

• Asian-Australasian Journal of Animal Sciences
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• 제9권1호
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• pp.31-35
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• 1996

An experiment was conducted on rainbow trout(Oncorhynclus mykiss) for eight weeks to investigate the growth performance of the fish fed with different dietary protein with constant diet energy of $20kJg^{-1}$. Four diets containing 25, 30, 35 and 40% crude protein were used. The highest mean final weight was obtained for the fish fed with diet having 35% protein. Growth performance in terms of Specific Growth Rate (SGR), Food Conversion Ratio (FCR) and Protein Efficiency Ratio (PER) were calculated for each diet. There were no significant differences in SGR but the highest value was exhibited by fish fed with 35% protein diet. Significant differences were found among FCR of different diets. Diets with 35 and 40% crude protein gave better FCR value than that of 25 and 30% crude protein. Although significant differences were not found between PER of different diets but PER of diet with 35% protein was found to be better than PER of both high and low protein diets (diets of 40 and 30% crude protein). It is concluded that diet having 35% protein with protein energy ratio of $17.53mgkJ^{-1}$ was suitable for rainbow trout (O. mykiss) among the protein spectrum used.

• Fisheries and Aquatic Sciences
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• 제1권2호
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• pp.192-200
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• 1998

This study was carried out to evaluate the effect of feeding higher protein feeds with lesser amount, but feeding the constant total protein input for all treatments, on water quality and nitrite toxicity in channel catfish ponds. There was no significant difference in survival rate among treatments $(P>0.05)$. Specific growth rate (SGR) for Treatment 1$(28\%\;protein\;and\;100\%\;of\;satiation)$ was significantly higher $(P>0.05)$ than for Treatment 3$(36\%\;protein\;and\;87.5\%\;of\;satiation)$, but not significantly higher than for Treatment 2 $(32\%\;protein\;and\;77.8\%\;of\;satiation)$ at constant digestible energy (DE), 3.08kcal/g (treatments 1, 2 and 3). At constant DE/P (treatments 4, 2 and 5), no significant difference in SGR was observed among treatments. Feed conversion ratio (FCR) slightly improved or improved as dietary protein level increased from $28\%$ to $32\%$ and feed allowance decreased by $12.5\%$, but did not improve as dietary protein level increased from $32\%$ to $36\%$ and feed allowance decreased by $22.2\%$, at constant DE and constant DE/P. There was no significant difference in water quality variables, such as total ammonia nitrogen (TAN), nitrite, chlorophyll a, soluble phosphorous concentrations among treatments, but significant difference in water quality variables over time as amount of feed fed increased $(P<0.0001)$. There was a trend toward increase in TAN and nitrite over time. A strong linear regression was observed between mean total ammonia nitrogen and nitrite for all treatments Y (Nitrite) =$0.04\times (TAN)+0.01$, $R_2=0.89$. Methemoglobin percent in the blood of catifish was not significantly different among treatments. And its mean value was $7.5\%$, which was relatively low, so that it was not serious problem in catfish production pond under these experiment conditions. There was the stronger linear regression between the percentage of Methemoglobin and the molar ratio of nitrite to chloride rather than nitrite alone: $Y\;(Methemoglobin\;\%)\;=\;58.45\;\times\;(NO^{2-}/Cl^-)\;+\;0.41,\;R^2=0.60$. These results indicate that deterioration of water quality has no strong impact on poor weight gain for $36\%$ dietary protein in this study.

• 한국작물학회지
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• 제46권3호
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• pp.202-208
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• 2001

본 연구는 광안벼를 공시하여 동일한 일장 조건에서 온도에 따른 벼의 출엽 및 출수 반응을 검토하여 온도에 의한 출엽속도 추정모델을 설정하고자 하였던 바 결과를 요약하면 다음과 같다. 1. 13시간의 동일한 일장에서 최종엽수는 15엽으로 온도에 따라 변하지 않았다. 2. 출엽속도는 저온에서 고온으로 갈수록 증가하였으며, 고온일수록 발육진전에 따른 출엽속도 감소정도가 컸다. 3. 온도변화에 따른 출엽속도는 15-27$^{\circ}C$의 범위에서는 온도가 높아짐에 따라 직선적으로 높아지는 1차 회귀 관계를 보였다. 임계온도는 발육진전에 따라 높아지는 경향을 보였다. 4. 임계온도를 1$0^{\circ}C$로 하였을 때 유효적산온도와 출엽과의 관계는 Logistic 함수에 의하여 가장 잘 표현되었다($R^2$=0.995). 하루당 출엽속도는 다음의 식으로 표현되었다. (equation omitted) 여기서 dL/dt는 출엽속도, T$_{i}$는 일평균기온, L은 엽수이고 a, b, c는 상수로 각각 41.8, 1098.38, -0.9273이다. 5. 위의 출엽속도 추정모델에 의해 추정된 값은 모델설정에 이용되지 않은 실제 조사 출엽속도와 가 0.99이상으로 추정 정확도가 매우 높았다.

• 천문학회보
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• 제42권1호
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• pp.39.2-39.2
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• 2017

Stars form through the gravitational collapse of molecular clouds. However, the rate at which a star gains most of its mass and the physics that drives the main phase of stellar growth is still unclear. The typical luminosity of observed protostars is smaller than what expected from the Shu's inside-out collapse model, which predicts a constant mass accretion rate. The episodic accretion model has been suggested as a solution of this luminosity problem. The JCMT Transient survey is a long term monitoring program using JCMT/SCUBA-2 to detect accretion variability of protostars in the eight nearby star-forming regions. Recently, we found a rise of the 850 micron flux at a clump in the Serpens main region at the rate of ~17% relative to the mean flux over previous observations. The submm clump is associated with a class I protostar, EC53, which has been reported as a binary system with a periodic variability. In this talk, we will provide a brief overview of the JCMT Transient Survey project, present the detection of the variable source, and discuss about follow-up observations.

• 디지털산업정보학회논문지
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• 제7권4호
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• pp.7-14
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• 2011

Infinite failure NHPP models presented in the literature exhibit either constant, monotonic increasing or monotonic decreasing failure occurrence rate per fault (hazard function). This infinite non-homogeneous Poisson process is model which reflects the possibility of introducing new faults when correcting or modifying the software. In this paper, polynomial hazard function have been proposed, which can efficiency application for software reliability. Algorithm for estimating the parameters used to maximum likelihood estimator and bisection method. Model selection based on mean square error and the coefficient of determination for the sake of efficient model were employed. In numerical example, log power time model of the existing model in this area and the polynomial hazard function model were compared using failure interval time. Because polynomial hazard function model is more efficient in terms of reliability, polynomial hazard function model as an alternative to the existing model also were able to confirm that can use in this area.

• 대한기계학회논문집A
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• 제25권11호
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• pp.1705-1712
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• 2001

Mechanical component has striation with constant width and SEM can estimate fracture type and loading condition. SEM has benefit to fatigue fracture analysis but striation can be observed according to the kind of material and range of crack growth rate and can't. In this case, it needs AFM that can measure 3-dimensional surface profile with resolution of atomic size. In this study. to find fracture reason of torsion-mounted blade in nuclear plant, we estimate the relation between stress intensity factor range and root mean square roughness in 12% Cr steel by AFM and predict in-service loading condition of turbine blade. failure analysis is performed by finite element method and Goodman diagram on torsion-mounted blade.

• 한국수산과학회지
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• 제31권6호
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• pp.842-851
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• 1998

한국 동해 남부 연안 일광만에 출현하는 요각류 Acartia steueri를 대상으로, 실험실에서 여러 온도와 과량의 먹이 (Isochrysis galbana와 Dunaliella salina) 조건에서 알에서 성체까지 사육하여 이들의 발생양상과 성장에 대하여 고찰하였다. 알의 부화시간($D_E$, day)과 온도 (T, $^{\circ}C$)와의 관계는, $D_E=744(T+3.5)^{-1.97}$로서 표현되었다. 평균 알의 부화성공률은 $8.4\~26.2^{\circ}C$의 온도 범위에서는 $88.4\%$이었으며, $3.7^{\circ}C$와 $30.0^{\circ}C$에서는 각각 $54.2\%$와 $31.4\%$로서 낮게 나타났는데, 이것은 이 종이 온대해역의 온도범위에 적응하고 있기 때문인 것으로 사료된다. 후기 배 발생양상은 등시간발생보다는 등비율발생을 보였으며, copepodite기의 체류시간이 nauplius기의 체류시간보다 전체적으로 길게 나타났다. Nauplius 1기의 체류시간이 유생단계 가운데서 가장 짧았고, nauplius 2기의 체류시간은 nauplius기 중에서 가장 길었다. 수컷은 copepodite 4기부터 형태적으로 암컷과 구분되었으며, 수컷이 암컷보다도 더 빨리 발생하였다. 주어진 온도에서의 중위 발생시간은 초기 배발생시간에 대한 각 유생단계의 비례상수를 곱하여 Belehradek방정식으로부터 계산되었다. $19.1^{\circ}C$에서 몸의 탄소무게는 시간에 따라 지수함수적으로 증가하였다. Nauplius 1기를 제외한 nauplius기의 평균 비성장률 (0.200 $d^{-1}$)은 copepodite기의 평균비성장률 (0.190 $d^{-1}$)과 유의한 차이가 없었다. Nauplius 6기의 비성장률은 0.107 $d^{-1}$로서 가장 낮았는데, 이것은 몸의 성장보다는 copepodite기로의 변태에 따른 에너지 소비와 관련이 있는 것 같다.

• 대한토목학회논문집
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• 제8권2호
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• pp.167-175
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• 1988

본 연구의 목적은 변동하중을 받는 구조부재의 피로거동을 해석하는 것이다. 이 연구의 해석과정은 다음과 같다. (1) 도로교의 실동응력파측정 및 통계적해석 (2) 등가의 일정진폭하중과, 통계적해석에 의해 모형화된 변동하중하(下)의 피로시험 (3) 등가응력개념의 RMC 모델에 의한 변동하중하(下)의 피로해석 등가응력개념에 의한 변동하중하(下)의 피로해석은 대부분의 구조용강재의 균열성장속도회귀지수가 $m{\fallingdotseq}3$이므로 이론적으로 RMC 모델이 합당하다. 변동하중하(下)의 피로시험해석결과 RMC 모델이 기존의 RMC 모델보다 변동하중에 의한 피로거동치(da/dN-${\Delta}K$, $N_f$)에 더 가까웠다. 또 변동하중하(下)에서 응력범위의 변화로 인한 interaction효과나 응력범위적용순서(sequence)효과 등은 피로수명에 거의 영향을 미치지 않으며, 응력범위변화속도가 클수록 피로균열성장속도가 빨라짐을 알 수 있었다.