• Journal of Biosystems Engineering
• /
• 제29권5호
• /
• pp.441-450
• /
• 2004

This study was performed to estimate mid and long term demands of a tractor, a rice transplanter, a combine and a grain dryer by using logistic curve function and Markov chain model. Field survey was done to decide some parameters far logistic curve function and Markov chain model. Ceiling values of tractor and combine fer logistic curve function analysis were 209,280 and 85,607 respectively. Based on logistic curve function analysis, total number of tractors increased slightly during the period analysed. New demand for combine was found to be zero. Markov chain analysis was carried out with 2 scenarios. With the scenario 1(rice price $10\%$ down and current supporting policy by government), new demand for tractor was decreased gradually up to 700 unit in the year 2012. For combine, new demand was zero. Regardless of scenarios, the replacement demand was increased slightly after 2003. After then, the replacement demand is decreased after the certain time. Two analysis of logistic owe function and Markov chain model showed the similar trend in increase and decrease for total number of tractors and combines. However, the difference in numbers of tractors and combines between the results from 2 analysis got bigger as the time passed.

• 한국산림과학회지
• /
• 제57권1호
• /
• pp.1-7
• /
• 1982

원래 인구증가곡선(人口增加曲線)으로 알려진 단순(單純) logistic 곡선(曲線)은 초본식물(草本植物)의 성장표현(成長表現)에도 이용(利用)되어 왔다. 초본(草本)의 경우 이론치(理論値)와 실측치(實測値) 사이의 적합도(適合度)는 만족(滿足)스러운 것으로 알려져 있다. 그러나 초본(草本)과는 특성(特性)이 상이(相異)한 목본식물(木本植物)의 성장(成長)에 단순(單純) logistic 곡선(曲線)이 적용(適用)된 예는 극히 드물다. 따라서 그에 대한 적합성(適合性) 여부는 아직 의문시 되고 있다. 본연구(本硏究)에서는 임분밀도관리(林分密度管理)의 기초(基礎)가 되고 있는 단순(單純) logistic 곡선(曲線)의 적합성(適合性)을 조사하기 위하여 이것을 소나무임분(林分)에 적용(適用)시켜 보았다. 적합성검정(適合性檢定)을 위해서는 Chi-square test가 채용되었다.

• 응용통계연구
• /
• 제14권1호
• /
• pp.71-80
• /
• 2001

로지스틱 회귀모형은 이항 반응자료에 대한 가장 보편적인 일반화 선형모형으로 독립변수에 대한 확률함수를 추정하는데 이용된다. 많은 실제적 상황에서 확률함수가 종형의 곡선형태로 표현되는데 이 경우에는 2차항을 포함한 로지스틱 회귀모형을 이용한 분석은 대칭성을 갖는 확률함수에 대한 가정으로 인해 비대칭 형태의 종형곡선에서는 확률함수의 신뢰성이 저하되고, 2차항을 포함하기 때문에 독립변수의 효과를 설명하기가 쉽지 않다는 제한점을 가지고 있다. 본 논문에서는 이러한 문제점을 해소하기 위해서 로지스틱 회귀분석과 반복적 이분법을 이용하여 종형의 형태에 관계없이 확률곡선을 추정하는 방법론을 제안하고 모의 실험을 통해 2차항을 포함한 로지스틱 회귀모형과 비교하고자 한다.

• Journal of Information Technology Applications and Management
• /
• 제12권2호
• /
• pp.1-13
• /
• 2005

This paper proposes a software-reliability growth model incoporating the amount of testing effort expended during the software testing phase after developing it. The time-dependent behavior of testing effort expenditures is described by a Logistic curve. Assuming that the error detection rate to the amount of testing effort spent during the testing phase is proportional to the current error content, a software-reliability growth model is formulated by a nonhomogeneous Poisson process. Using this model the method of data analysis for software reliability measurement is developed. After defining a software reliability, This paper discusses the relations between testing time and reliability and between duration following failure fixing and reliability are studied. SRGM in several literatures has used the exponential curve, Railleigh curve or Weibull curve as an amount of testing effort during software testing phase. However, it might not be appropriate to represent the consumption curve for testing effort by one of already proposed curves in some software development environments. Therefore, this paper shows that a logistic testing-effort function can be adequately expressed as a software development/testing effort curve and that it gives a good predictive capability based on real failure data.

• 응용통계연구
• /
• 제7권2호
• /
• pp.249-261
• /
• 1994

본 연구의 목적은 한국인구의 연도별 추정과 그 장래인구의 예측을 위한 단순 Logistic Curve의 모수(母數)들을 추정하는데 있다. 즉 1949년부터 1990년에 이르는 9회에 걸친 인구 Census 자료를 토대로 하고, 3-군법(3-群法)을 적용하여 모수들을 추정하므로서 연도별 총인구들의 곡선추계를 위한 Logistic Curve를 얻었다. 아울러 이 곡선에 의하여 1950년부터 1990년까지의 Census와 Census 사이의 총인구를 연도별로 추정하였으며, 다른 한편 1991년부터 2010년에 이르기까지 장래인구를 예측하였다. 뿐만 아니라 최근 한국인구 성장의 상한점근치(Upper Asymptote)로 58,616천명을 제시할 수 있었다.

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

• Asian Pacific Journal of Cancer Prevention
• /
• 제14권10호
• /
• pp.5891-5893
• /
• 2013

Incidence/mortality of liver cancer follow logistic curves because there is a limit reflecting the prevalence of hepatitis virus carriers in the cohort. The author fitted logistic curves to incidence/mortality data covering the nine five-year cohorts born in 1911-1955 of both sexes. Goodness-of-fit of logistic curves was sufficiently precise to be used for future predictions. Younger cohorts born in 1936 or later were predicted to show constant decline in incidence/mortality in the future. The male cohort born in 1931-35 showed an elevated incidence/mortality of liver cancer early in their lives supporting the previous claim that this particular cohort had suffered massive HCV infection due to nation-wide drug abuse in the 1950s. Declining case-fatality observed in younger cohorts suggested improved treatment of liver cancer. This study demonstrated that incidence/mortality of liver cancer follow logistic curves and fitted logistic formulae can be used for future prediction. Given the predicted decline of incidence/mortality in younger cohorts, liver cancer is likely to be lost to history in the not-so-distant future.

• 한국구조물진단유지관리공학회 논문집
• /
• 제7권2호
• /
• pp.135-140
• /
• 2003

As a construction technique is developed recently, the construction space and construction period are considered to important matters. Especially, in case of construction period, several method is proposed for strength control in the construction field. However there are very little strength control models for application of internal condition. The purpose of this study is to develop a strength control model for application of variety internal condition at construction field. The results are as follows ; 1) According to the results of compressive strength of concrete evaluated by logistic curve and proposed curve, proposed curve is applicable of construction field because there is similar relation with logistic curve. 2) It is shown that the construction period is shortened by reduction of the formwork removal time, because a predicted compressive strength of using the new curve is higher than the proposed compressive strength of standard.

• 한국소음진동공학회논문집
• /
• 제20권6호
• /
• pp.555-561
• /
• 2010

Predicted noise level has been used to assess the annoyance response since noise map was generalized and being the normal method to assess the environmental noise. Unfortunately using predicted noise level to derive the annoyance prediction curve caused some problems. The data have to be grouped manually to use the annoyance prediction curve. The aim of this paper is to propose the method to handle the predicted noise level and the survey data for annoyance prediction curve. This paper used the percentage of persons annoyed(%A) and the percentage of persons highly annoyed as the descriptor of noise annoyance in a population. The logistic regression method was used for deriving annoyance prediction curve. It is concluded that the method of dichotomizing data and logistic regression was suitable to handle the predicted noise level and survey data.

• 한국화재소방학회논문지
• /
• 제33권6호
• /
• pp.20-27
• /
• 2019

본 연구는 화재 시 열출력 급상승 구간에 대한 정확한 열방출율을 예측하기 위한 새로운 함수를 개발하여 제안하는 것을 목적으로 하였다. 현재 화재공학에서 사용되고 있는 'αt²' 곡선은 화재시스템 공학 관점에서 비효율적이며 실효성 저하를 초래하므로 열방출율의 예측오차를 최소화시킬 필요가 있다. 'αt²'과 비교하여 보다 논리적인 배경과 형태적으로 유사성을 가진 로지스틱 함수 이론을 기반으로 화재 급성장 구간은 물론 화재 초기 단계까지 적용 가능한 새로운 예측 함수를 개발하였다. 개발된 함수는 더 넓은 화재성장 구간에서 정확도 높은 예측결과를 갖는 것으로 본 연구에서 증명되었다. 이 연구결과는 향후 화재성장패턴 연구의 개발과 함께 화재공학의 발전을 위해 적용될 것이다.