• Title, Summary, Keyword: logistic curve

Search Result 253, Processing Time 0.04 seconds

The Study for Software Future Forecasting Failure Time Using Curve Regression Analysis (곡선 회귀모형을 이용한 소프트웨어 미래 고장 시간 예측에 관한 연구)

  • Kim, Hee-Cheul;Shin, Hyun-Cheul
    • Convergence Security Journal
    • /
    • v.12 no.3
    • /
    • pp.115-121
    • /
    • 2012
  • Software failure time presented in the literature exhibit either constant, monotonic increasing or monotonic decreasing. For data analysis of software reliability model, data scale tools of trend analysis are developed. The methods of trend analysis are arithmetic mean test and Laplace trend test. Trend analysis only offers information of outline content. In this paper, we discuss forecasting failure time case of failure time censoring. In this study, we predict the future failure time by using the curve regression analysis where the s-curve, growth, and Logistic model is used. The proposed prediction method analysis used failure time for the prediction of this model. Model selection using the coefficient of determination and the mean square error were presented for effective comparison.

Meteorological Determinants of Forest Fire Occurrence in the Fall, South Korea

  • Won, Myoung-Soo;Miah, Danesh;Koo, Kyo-Sang;Lee, Myung-Bo;Shin, Man-Yong
    • Journal of Korean Society of Forest Science
    • /
    • v.99 no.2
    • /
    • pp.163-171
    • /
    • 2010
  • Forest fires have potentials to change the structure and function of forest ecosystems and significantly influence on atmosphere and biogeochemical cycles. Forest fire also affects the quality of public benefits such as carbon sequestration, soil fertility, grazing value, biodiversity, or tourism. The prediction of fire occurrence and its spread is critical to the forest managers for allocating resources and developing the forest fire danger rating system. Most of fires were human-caused fires in Korea, but meteorological factors are also big contributors to fire behaviors and its spread. Thus, meteorological factors as well as social factors were considered in the fire danger rating systems. A total of 298 forest fires occurred during the fall season from 2002 to 2006 in South Korea were considered for developing a logistic model of forest fire occurrence. The results of statistical analysis show that only effective humidity and temperature significantly affected the logistic models (p<0.05). The results of ROC curve analysis showed that the probability of randomly selected fires ranges from 0.739 to 0.876, which represent a relatively high accuracy of the developed model. These findings would be necessary for the policy makers in South Korea for the prevention of forest fires.

A new formulation for calculation of longitudinal displacement profile (LDP) on the basis of rock mass quality

  • Rooh, Ali;Nejati, Hamid Reza;Goshtasbi, Kamran
    • Geomechanics and Engineering
    • /
    • v.16 no.5
    • /
    • pp.539-545
    • /
    • 2018
  • Longitudinal Displacement Profile (LDP) is an appropriate tool for determination of the displacement magnitude of the tunnel walls as a function of the distance to the tunnel face. Some useful formulations for calculation of LDP have been developed based on the monitoring data on site or by 3D numerical simulations. However, the presented equations are only based on the tunnel dimensions and for different quality of rock masses proposed a unique LDP. In the present study, it is tried to present a new formulation, for calculation of LDP, on the basis of Rock mass quality. For this purpose, a comprehensive numerical simulation program was developed to investigate the effect of rock mass quality on the LDP. Results of the numerical modelling were analyzed and the least square technique was used for fitting an appropriate curve on the derived data from the numerical simulations. The proposed formulation in the present study, is a logistic function and the constants of the logistic function were predicted by rock mass quality index (GSI). Results of this study revealed that, the LDP curves of the tunnel surrounded by rock masses with high quality (GSI>60) match together; because the rock mass deformation varies over an elastic range.

Cell Disruption of Microalgae by Low-Frequency Non-Focused Ultrasound (저주파 초음파를 이용한 미세조류 파쇄)

  • Bae, Myeong-Gwon;Choi, Jun-Hyuk;Park, Jong-Rak;Jeong, Sang-Hwa
    • Journal of the Korean Society of Manufacturing Process Engineers
    • /
    • v.19 no.2
    • /
    • pp.111-118
    • /
    • 2020
  • Recently, bioenergy research using microalgae, one of the most promising biofuel sources, has attracted much attention. Cell disruption, which can be classified as physical or chemical, is essential to extract functional ingredients from microalgae. In this study, we investigated the cell disruption efficiency of Chlorella sp. using low-frequency non-focused ultrasound (LFNFU). This is a continuously physical method that is superior to chemical methods with respect to environmental friendliness and low processing cost. A flat panel photobioreactor was employed to cultivate Chlorella sp. and its growth curve was fitted both with Logistic and Gompertz models. The temporal change in cell reduction by cell disruption using LFNFU was fitted with a Logistic model. The experimental conditions that were investigated were the initial concentration of microalgal cells, relative amplitude of output ultrasound waves, processing volume of microalgal cells, and initial pH value. The optimal conditions for the most efficient cell disruption were determined through the various tests.

Predicting Suicidal Ideation in College Students with Mental Health Screening Questionnaires

  • Shim, Geumsook;Jeong, Bumseok
    • Psychiatry investigation
    • /
    • v.15 no.11
    • /
    • pp.1037-1045
    • /
    • 2018
  • Objective The present study aimed to identify risk factors for future SI and to predict individual-level risk for future or persistent SI among college students. Methods Mental health check-up data collected over 3 years were retrospectively analyzed. Students were categorized as suicidal ideators and non-ideators at baseline. Logistic regression analyses were performed separately for each group, and the predicted probability for each student was calculated. Results Students likely to exhibit future SI had higher levels of mental health problems, including depression and anxiety, and significant risk factors for future SI included depression, current SI, social phobia, alcohol problems, being female, low self-esteem, and number of close relationships and concerns. Logistic regression models that included current suicide ideators revealed acceptable area under the curve (AUC) values (0.7-0.8) in both the receiver operating characteristic (ROC) and precision recall (PR) curves for predicting future SI. Predictive models with current suicide non-ideators revealed an acceptable level of AUCs only for ROC curves. Conclusion Several factors such as low self-esteem and a focus on short-term rather than long-term outcomes may enhance the prediction of future SI. Because a certain range of SI clearly necessitates clinical attention, further studies differentiating significant from other types of SI are necessary.

Selecting the Best Soil Particle-Size Distribution Model for Korean Soils

  • Hwang, Sang-Il
    • Journal of Environmental Policy
    • /
    • v.2 no.1
    • /
    • pp.77-86
    • /
    • 2003
  • Particle-size distributions (PSDs) are widely used for the estimation of soil hydraulic properties. The objective of this study was to select the best model among the nine PSD models with different underlying assumptions, by using a variety of Korean soils. The Fredlund model with four parameters, the logistic growth curve, and Weibull distribution model showed the highest performance compared to the other models with the majority of soils studied. It was interesting to find that the logistic growth function with no fitting parameters showed a great fitting performance.

  • PDF

A Study on Transportation Systems of Container Cargoes in Busan Port (부산항 컨테이너 화물수송체계에 관한 연구)

  • 오석기;오윤표;윤칠용
    • Journal of Korean Port Research
    • /
    • v.15 no.1
    • /
    • pp.19-26
    • /
    • 2001
  • The purpose of this study is to improve the strategies for transportation systems of container cargoes in Busan port. Therefore, container cargoes forecasting is done through logistic methods based on past trends. In 2011, container cargoes demand was forecasted 8.791 million TEU(T/S including 12.559 million TEU). In order to improve transportation systems of container cargoes, the conclusions of this study can be summarized as follows ; \circled1 port facilities expansion, \circled2 diversity of container transport modes, \circled3 make up ICD and exclusive container roads, \circled4 the second Seoul-Busan Expressway.

  • PDF

Technological status of Biocluster in Daedeok Innopolis: With the focused on the patent analysis (대덕 바이오클러스터의 기술현황: 특허 분석을 중심으로)

  • Kim, Yoon-Dong;Choi, Jong-In
    • Journal of Technology Innovation
    • /
    • v.16 no.1
    • /
    • pp.215-237
    • /
    • 2008
  • KIPRIS patent database was analyzed for identifying the technological status of Daedeok Innopolis Biocluster. It was found that the pattern of activities among various technological areas in Daedeok Biocluster is similar to that of an advanced country rather than those of other cities in Korea. The technological growth in Daedeok Innopolis Biocluster is in the progressive stage, which may be due to the innovative activities rather than the rise in the number of new firms or institutes. The concentration of technology in Daedeok Innopolis Biocluster is a favorable condition for the innovation activities. The trend for the technological concentration was remarkably consistent with the growth curve that a population increases according to the logistic equation. The logistic growth may be represented by the result of competition due to the limited resource allocation and then innovation cluster is corresponding to the ecosystem composed by biological individuals. There is strong competition in Daedeok Innopolis Biocluster in around 2009, so the government might make a policy to encourage the technological diversity for healthy knowledge ecosystem.

  • PDF

Studies on the Mathematical Analysis of Growth Kinetics in Tobacco (Nicotiana tabacum L. ) I. Growth Curve and Growth Velocity of Total Dry Weight. (담배의 생장반응에 관한 수리해석적 연구 I. 전건물중의 생장곡선과 생장속도)

  • 김용암;변주섭
    • Journal of the Korean Society of Tobacco Science
    • /
    • v.3 no.2
    • /
    • pp.109-114
    • /
    • 1981
  • This experiment was conducted with three varieties (Hicks, Burley 21, Sohyang) and cropping systems (Improved mulching, Mulching, Non mulching) of NC 2326 to analyze growth kinetics by means of growth function involving its velocity and accelerated velocity. The basic growth data were obtained by harvest method at interval of ten days from transplanting to hundred days and analyzed by , regression equation, determinant of matrix, and differentiation. The plot of total dry weight of leaves, stalk and roots per a plant vs. time forms a sigmoid curve and its function fitted logistic satisfactorily. Tobacco plant grows at an accelerated velocity. And growth velocity, symmetric about an inflection point, is proportional to biomass attained and to the difference between biomass attained and the maximum, and to the decrease according to the biomass. Of varieties and cropping systems, the most maximum velocity was 9.58g per day per plant in mulching cultivation of NC 2326 and maximum accelerated velocity was 264mg per $day^2$ per plant in Burley 21.

  • PDF

Soft Set Theory Oriented Forecast Combination Method for Business Failure Prediction

  • Xu, Wei;Xiao, Zhi
    • Journal of Information Processing Systems
    • /
    • v.12 no.1
    • /
    • pp.109-128
    • /
    • 2016
  • This paper presents a new combined forecasting method that is guided by the soft set theory (CFBSS) to predict business failures with different sample sizes. The proposed method combines both qualitative analysis and quantitative analysis to improve forecasting performance. We considered an expert system (ES), logistic regression (LR), and support vector machine (SVM) as forecasting components whose weights are determined by the receiver operating characteristic (ROC) curve. The proposed procedure was applied to real data sets from Chinese listed firms. For performance comparison, single ES, LR, and SVM methods, the combined forecasting method based on equal weights (CFBEWs), the combined forecasting method based on neural networks (CFBNNs), and the combined forecasting method based on rough sets and the D-S theory (CFBRSDS) were also included in the empirical experiment. CFBSS obtains the highest forecasting accuracy and the second-best forecasting stability. The empirical results demonstrate the superior forecasting performance of our method in terms of accuracy and stability.