• 한국농공학회논문집
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• 제62권1호
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• pp.61-70
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• 2020

To estimate the ventilation volume of mechanically ventilated swine farms, various regression models were applied, and errors were compared to select the regression model that can best simulate actual data. Linear regression, linear spline, polynomial regression (degrees 2 and 3), logistic curve, generalized additive model (GAM), and gompertz curve were compared. Overfitting models were excluded even when the error rate was small. The evaluation criteria were root mean square error (RMSE) and mean absolute percentage error (MAPE). The evaluation results indicated that degree 3 exhibited the lowest error rate; however, an overestimation contradiction was observed in a certain section. The logistic curve was the most stable and superior to all the models. In the estimation of ventilation volume by all of the models, the estimated ventilation volume of the logistic curve was the smallest except for the model with a large error rate and the overestimated model.

• 한국수산과학회지
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• 제23권5호
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• pp.385-393
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• 1990

전남 연안역에 출현하는 멸치 치어의 성장을 연구하기 위하여 전남 연안역의 3개 정점에서 1988년 5월부터 1989년 8월 사이에 정치망으로 멸치를 채집하였으며, 멸치의 연령은 이석에 나타난 성장선수로부터 결정하였다. 체장의 성장은 Gompertz의 성장식으로 표현하면 $$L =5.76{\times}E xp(1.66 \times(1- E xp(-0.44\;t)))$$, 또는 $$L=3.7{\times}E xp(1.99\times(1-E xp(-0.0614\;t)))$$로 표시된다. 20일부터 40일 사이의 평균 일일성장율은 0.38mm/day였으며, 일일성장율은 10일경에 최대를 보인후 서서히 감소하는 것으로 나타났다. 멸치의 성장은 채집시기나 채집장소에 관계없이 거의 일정한 것으로 나타났다.

• 산업경영시스템학회지
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• 제32권4호
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• pp.184-191
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• 2009

In a technological driven environment, a depreciation estimate which is based on traditional life analysis results in a decelerated rate of capital recovery. This time pattern of technological growths models needs to be incorporated into life analysis framework especially in those industries experiencing fast technological changes. The approximation technique for calculating the variance can be applied to the six growth models that were selected by the degree of skewness and the transformation of the functions. For the Pearl growth model, the Gompertz growth model, and the Weibull growth model, the errors have zero mean and a constant variance over time. However, transformed models like the linearized Fisher-Pry model, the linearized Gompertz growth model, and the linearized Weibull growth model have increasing variance from zero to that point at which inflection occurs. It can be recommended that if the variance of error over time is increasing, then a transformation of observed data is appropriate.

• 한국식물병리학회지
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• 제14권2호
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• pp.150-156
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• 1998

To develop a model for prediction of turnip mosaic virus(TuMV) disease progress of Chinese cabbage based on weather information and number of TuMV vector aphids trapped in Taegwallyeong alpine area, data were statistically processed together. As the variables influenced on TuMV disease progress, cumulative portion(CPT) above 13$^{\circ}C$ in daily average temperature was the most significant, and solar radiation, duration of sunshine, vector aphids and cumulative temperature above $0^{\circ}C$ were significant. When logistic model and Gompertz model were compared by detemining goodness of fit for TuMV disease progress using CPT as independent variable, regression coefficient was higher in the logistic model than in the Gompertz model. Epidemic parameters, apparent infection rate and initial value of logistic model, were estimated by examining the relationship between disease proportion linearized by logit transformation equation, In(Y/Yf-Y) and CPT. Models able to describe the progression of TuMV disease were formulated in Y=100/(1+128.4 exp(-0.013.CPT.(-1(1/(1+66.7.exp(-0.11.day). Calculated disease progress from the model was in good agreement with investigated actual disease progress showing high significance of the coefficient of determination with 0.710.

• Journal of the Korean Data Analysis Society
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• 제20권6호
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• pp.2721-2731
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• 2018

This study purposes to derive the predictive model for the cold tolerance of Brassica napus, using the data collected in the Tree Breeding Lab of Gyeongsang National University during July and August of 2016. Three Brassica napus samples were treated at each of low temperatures from $4^{\circ}C$ to $-12^{\circ}C$ by decrement of $4^{\circ}C$, step by step, and electrolyte leakage levels were measured at each stage. Electrolyte leakages were observed tangibly from $-4^{\circ}C$. We tried to fit the six nonlinear regression models to the electrolyte leakage data of Brassica napus: 3-parameter logistic model, baseline logistic model, 4-parameter logistic model, (4-1)-parameter logistic model, 3-parameter Gompertz model, and (3-1)-parameter Gompertz model. The baseline levels of the electrolyte leakage estimated by these models were 4.81%, 4.07%, 4.19%, 4.07%, 4.55%, and 0%, respectively. The estimated median lethal temperature, LT50, were $-5.87^{\circ}C$, $-6.31^{\circ}C$, $-6.05^{\circ}C$, $-6.35^{\circ}C$, $-4.98^{\circ}C$, and $-5.15^{\circ}C$, respectively. We compared and discussed the measures of goodness of fit to select the appropriate nonlinear regression model.

• The Journal of Asian Finance, Economics and Business
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• 제8권1호
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• pp.207-215
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• 2021

The number of tourists visiting Nepal has shown rapid growth in recent years, and Nepal is expecting more tourist arrivals in the future. This paper, thus, attempts to analyze the tourist arrivals in Nepal and predict the number of visitors until 2025. This paper has examined the international tourist arrival trend in Nepal using the Gompertz and Logistic growth model. The international tourist arrival data from 1991 to 2018 is used to investigate international tourist arrival trends. The result of the analysis found that the Gompertz model performs a better fit than the Logistic model. The study further forecast the expected tourist arrival below one million (844,319) by 2025. Nevertheless, the government of Nepal has the goal of two million tourists in a year. The present study also discusses system dynamics scenarios for the two million potential visitors within a year. Scenario analysis shows that proper advertisement and positive word-of-mouth will be key factors in achieving a higher number of tourists. The current study could fill the gap of theoretical and empirical forecasting of tourist arrivals in the Nepalese tourism industry. Also, the study findings would be beneficial for government officers, planners and investors, and policy-makers in the Nepalese tourism industry.

• Journal of Preventive Medicine and Public Health
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• 제56권1호
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• pp.59-66
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• 2023

Objectives: The aim of this study was to evaluate the effect of body weight status and sleep duration on the discrete-time hazard of menarche in Korean schoolgirls using multiple-point prospective panel data. Methods: The study included 914 girls in the 2010 Korean Children and Youth Panel Study who were in the elementary first-grader panel from 2010 until 2016. We used a Gompertz regression model to estimate the effects of weight status based on age-specific and sex-specific body mass index (BMI) percentile and sleep duration on an early schoolchild's conditional probability of menarche during a given time interval using general health condition and annual household income as covariates. Results: Gompertz regression of time to menarche data collected from the Korean Children and Youth Panel Study 2010 suggested that being overweight or sleeping less than the recommended duration was related to an increased hazard of menarche compared to being average weight and sleeping 9 hours to 11 hours, by 1.63 times and 1.38 times, respectively, while other covariates were fixed. In contrast, being underweight was associated with a 66% lower discrete-time hazard of menarche. Conclusions: Weight status based on BMI percentiles and sleep duration in the early school years affect the hazard of menarche.

• 농업과학연구
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• 제48권4호
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• pp.987-1001
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• 2021

One of the most critical issues in the dairy industry, alongside the low birth rate and the aging population, is the decrease in demand for milk. In this study, the consumption trends of 12 major dairy products distributed in Korea were predicted using a logistic model, the Gompertz model, and the Bass diffusion model, which are representative S-shaped growth models. The 12 dairy products are fermented milk (liquid type, cream type), butter, milk powder (modified, whole, skim), liquid milk (market, flavored), condensed milk, cheese (natural, processed), and cream. As a result of the analysis, the growth potential of butter, condensed milk, natural cheese, processed cheese, and cream consumption among the 12 dairy products is relatively high, whereas the growth of the remaining dairy product consumption is expected to stagnate or decrease. However, butter and cream are by-products of the skim milk powder manufacturing process. Therefore, even if the consumption of butter and cream grows, it is difficult to increase the demand of domestic milk unless the production of skim milk powder produced from domestic milk is also increased. Therefore, in order to support the domestic dairy industry, policy support should be focused on increasing domestic milk usage for the production of condensed milk, natural cheese, and processed cheese.

• 유기물자원화
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• 제24권1호
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• pp.21-29
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• 2016

혐기성 소화의 주요 조건 중 하나인 C/N비의 경우 하수슬러지는 5.40으로 낮게 나타난 반면 음폐수(Food waste leachate)는 21.84로 높게 나타났다. C/N비가 낮을 경우 혐기성소화의 저해 요인으로 작용될 수 있기 때문에 음폐수의 높은 유기물 농도 및 C/N 비를 활용하여 메탄가스 발생량 증가시킬 수 있었다. Tchobanoglous이 제안한 이론적 메탄가스 발생량 예측수식을 적용하여 메탄 및 바이오가스 발생량을 산정한 결과 하수슬러지 단일 혐기소화의 경우 $305.6mL{\cdot}CH_4/g{\cdot}VS$, $689.4mL{\cdot}CH_4/g{\cdot}VS$의 메탄, 바이오가스가 발생하였고 음폐수 : 하수슬러지를 1:9로 혼합한 시료는 약 $322mL{\cdot}CH_4/g{\cdot}VS$, 3:7시료에서는 약 $354mL{\cdot}CH_4/g{\cdot}VS$, 5:5시료에서는 약 $386mL{\cdot}CH_4/g{\cdot}VS$의 메탄가스가 발생하는 것으로 분석되었다. BMP 실험 결과 1:9, 3:7, 5:5 비율로 병합 처리한 경우 각각 약 233, 298, $344mL{\cdot}CH_4/g{\cdot}VS$의 메탄가스가 발생하였다. 따라서 음폐수의 혼합비율이 높아질수록 메탄가스 발생량은 증가하였고 하수슬러지와 음폐수의 혼합비율에 따른 병합처리 시 하수슬러지 단독처리에 비해 다량의 메탄가스가 발생되었다. BMP 실험을 통해 생산된 메탄가스의 누적생산 곡선을 Modified Gompertz model과 first order kinetic model에 적용하여 추정한 결과, 메탄생성량은 Modified Gompertz model에서는 238.5, 302.3, $353.6mL/g{\cdot}VS$ 발생하였고 first order kinetic model에서는 242.8, 312.5, $365.5mL/g{\cdot}VS$로 음폐수와의 혼합비율이 증가할수록 높게 나타났으며, 최대 메탄생성속도의 경우 3:7비율에서 $48.2mL/gVS{\cdot}day$로 최대 메탄생성 속도를 보였다. first order kinetic model의 1차 반응속도상수 k값은 1:9, 3:7, 5:5 비율에 따라 0.32, 0.22, $0.08day^{-1}$ 나타났다. 1차 반응속도 상수의 경우 음폐수의 혼합비율이 낮을수록 높게 나타났다. Modified Gompertz와 first order kinetic model 모두 실험결과를 잘 모사하였으며, 실험결과와 모의결과의 적합도를 나타내는 상관계수($R^2$)의 경우 0.92~0.98으로 높은 상관성을 나타내었다.

• Journal of Animal Science and Technology
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• 제45권5호
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• pp.711-724
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• 2003

본 연구는 1970년대 이후 축산기술연구소 대관령지소에서 출생한 한우 암소로부터 한우암소의 성장곡선 모수에 영향하는 환경요인의 효과를 추정함으로써 한우의 개량을 위한 정보를 얻고자 실시하였다. Gompertz 모형, von Bertalanffy 모형 및 Logistic 모형에 의해 추정된 성장곡선 모수들의 분산분석 결과는 모두 같은 경향을 나타냈는데, 출생년도-계절의 효과는 성숙체중, 성장비 및 성숙률 모두에게 영향을 미치며, 어미소 연령의 효과는 성장비에서만 영향을 미쳤고, 공변이로 선형 모형에 포함된 최종 체중 측정시 일령의 효과는 성장비를 제외한 성숙체중과 성숙률에 영향을 미치는 것으로 나타났다. Gompertz 모형, von Bertalanffy 모형 및 Logistic 모형에 의해 개체별로 추정한 모수 A는 가을에 출생한 개체들이 봄에 출생한 개체들에 비해 10.47${\pm}$7.9, 19.01${\pm}$9.79 및 13.43${\pm}$5.94kg 더 무거웠으며 Logistic 모형에서 통계적 유의성(P〈.05)이 있었으며, 성숙률은 봄에 출생한 개체들이 가을에 출생한 개체들에 비해 0.00021${\pm}$0.00009, 0.00022${\pm}$0.00009 및 0.00041${\pm}$0.00013으로 높았고 통계적인 유의성(P〈.05)이 있었다. 어미소 연령 그룹별 성장모수들의 최소자승평균치를 보면 연령이 2세나 3세인 어미소로부터 태어난 암소들은 다른 연령그룹의 어미소로부터 태어난 암소들에 비해 성숙체중은 크지 않으면서 성장비가 크고 성숙률은 작은 경향을 보이고 있는데 성숙체중은 크지 않으면서 성장비가 크다는 것은 생시체중이 작다는 것을 시사한다. 따라서 한우 암소를 1산이나 2산까지만 번식에 이용한 후 비육 출하하는 생산체계를 유지하는 집단에서는 축군의 생시체중이 작아지고 성숙체중도 작아지는 현상이 나타날 우려가 있다. 본 연구에서는 성장곡선 모수에 영향을 미치는 환경요인으로서 출생년도-계절과 어미소 연령을 고정효과로 하고 여기에 최종 체중 측정시 일령의 1차식 효과를 공변이로 추가시켰는데, 분산분석 결과 최종 체중 측정시 일령이 세 가지 성장 모형으로 추정한 성숙체중과 성숙률에 영향을 미치는 것으로 나타났다. 이러한 결과들은 최종 체중 측정시 일령에 따라서 성장특성이 달라질 수 있음을 의미하므로 성장곡선 모형의 연구를 위해서는 최종 체중 측정 시점을 변이요인으로 고려하여야 한다. 그리고 한우의 성장 패턴을 좀더 잘 규명하기 위해서는 2차 이상의 다항회귀식 효과에 대한 검토가 필요하다.