• Title/Summary/Keyword: logistic regression equation

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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
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    • v.3 no.2
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    • pp.109-114
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    • 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.

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A Study on the Competitiveness Improvement of Coastal Shipping for Northeast Asia Logistics-Hub (동북아 물류거점화를 위한 연안해운 경쟁력 제고방안에 관한 연구)

  • Lee Yon-Jae;Ahn Ki-Myung;Kim Kwang-Hee;Kim Hyun-Duk
    • Journal of Navigation and Port Research
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    • v.29 no.6 s.102
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    • pp.501-508
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    • 2005
  • The purpose of this paper is to present the alternatives for improving coostal shipping logistics system to be a logistic hub-nation with a competitive edge. For this purpose, major environmental factors in Northeast Asia and accordingly its effects are analyzed And then the effects of coastal shipping system's development strategy is analysed using Structural Equation Model and Multiple Regression Model. Research results show that three types of coastal shipping development strategy( connected transportation system, structure of coastal shipping system, governmental support policy) will contribute much to being a logistics hub-nation. From the results, some implications are derived as follows. Firstly, environmental-friendly balanced ocean-coastal transport system is required Secondly, a excusive feeder port, Ro-Ro ship & high-speed ship are necessary to establish the one-stop logistics service system Finally, governmental support policy and subsidy(tax-exempted oil & various tax benefits) are required to reactivate lagged coastal shipping system to be a logistic hub-nation with a competitive edge.

Growth curve estimates for wither height, hip height, and body length of Hanwoo steers (Bos taurus coreanae)

  • Park, Hu-Rak;Eum, Seung-Hoon;Roh, Seung-Hee;Sun, Du-Won;Seo, Jakyeom;Cho, Seong-Keun;Lee, Jung-Gyu;Kim, Byeong-Woo
    • Korean Journal of Agricultural Science
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    • v.44 no.3
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    • pp.384-391
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    • 2017
  • Growth curves in Hanwoo steers were estimated by Gompertz, Von Bertalanffy, Logistic, and Brody nonlinear models using growth data collected by the Hanwoo Improvement Center from a total of 6,973 Hanwoo (Bos taurus coreanae) steers 6 to 24 months old that were born between 1996 and 2015. The data included three parameters: A, mature size of body measurement; b, growth ratio; and, k, intrinsic growth rate. Nonlinear regression equations for wither height according to Gompertz, Von Bertalanffy, Logistic, and Brody models were $Y_t=144.7e^{-0.5869e^{-0.00301t}}$, $Y_t=145.3(1-0.1816e^{-0.00284t})^3$, $Y_t=143.1(1+0.7356e^{-0.00352t})^{-1}$, and $Y_t=146.8(1+0.4700e^{-0.00249t})^1$, respectively, while those for hip height were $Y_t=144.5e^{-0.5549e^{-0.00312t}}$, $Y_t=145.0(1-0.1724e^{-0.00295t})^3$, $Y_t=143.1(1+0.6863e^{-0.00360t})^{-1}$, and $Y_t=146.2(1+0.4501e^{-0.00263t})^1$, respectively. Equations for body length $Y_t=174.1e^{-0.8342e^{-0.00289t}}$, $Y_t=175.8(1-0.2500e^{-0.00265t})^3$, $Y_t=170.0(1+1.1548e^{-0.00363t})^{-1}$, and $Y_t=180.3(1+0.6077e^{-0.00215t})^1$, respectively, for the same models. Among the four models, the Brody model resulted in the lowest mean square error, with mean square errors of 31.79, 30.57, and 42.13, respectively, for wither height, hip height, and body length. Also, an estimated birth wither height, birth hip height, and birth body length (77.98, 80.57, and 70.97 cm, respectively) were lower in the Brody model than in other models. An inflection point was not observed during the growth phase of Hanwoo steer according to the growth curves calculated using Gompertz, Von Bertalanffy, and Logistic models. Based on the results, we concluded that the regression equation using the Brody model was the most appropriate among the four growth models. To obtain more accurate parameters, however, using data from a wider production period (from birth to shipping) would be required, and the development of a suitable model for body conformation traits would be needed.

Risk Factors of Work-related Upper Extremity Musculoskeletal Disorders in Male Shipyard Workers: Structural Equation Model Analysis

  • Park, Byung-Chan;Cheong, Hae-Kwan;Kim, Eun-A;Kim, Soo-Geun
    • Safety and Health at Work
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    • v.1 no.2
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    • pp.124-133
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    • 2010
  • Objectives: This study was conducted to develop a model describing the interaction between lifestyle, job, and postural factors and parts of the upper extremities in shipyard workers. Methods: A questionnaire survey was given to 2,140 workers at a shipyard in Ulsan City. The questionnaire consisted of questions regarding the subjects' general characteristics, lifestyle, tenure, physical burden, job control, posture and musculoskeletal symptoms. The overall relationship between variables was analyzed by a structural equation model (SEM). Results: The positive rate of upper extremity musculoskeletal symptoms increased in employees who worked longer hours, had severe physical burden, and did not have any control over their job. Work with a more frequent unstable posture and for longer hours was also associated with an increased positive rate of musculoskeletal symptoms. Multiple logistic regression analysis showed that unstable posture and physical burden were closely related to the positive rate of musculoskeletal symptoms after controlling for age, smoking, drinking, exercise, tenure, and job control. In SEM analysis, work-related musculoskeletal disease was influenced directly and indirectly by physical and job stress factors, lifestyle, age, and tenure (p < 0.05). The strongest correlations were found between physical factors and work-related musculoskeletal disease. Conclusion: The model in this study provides a better approximation of the complexity of the actual relationship between risk factors and work-related musculoskeletal disorders. Among the variables evaluated in this study, physical factors (work posture) had the strongest association with musculoskeletal disorders.

Model construction with core questions from a course evaluation survey (핵심 문항들을 활용한 모델링-강의 평가 자료를 활용한 사례연구)

  • Pak, Ro-Jin
    • Journal of the Korean Data and Information Science Society
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    • v.20 no.6
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    • pp.1075-1083
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    • 2009
  • The scientific research method went through construction of hypothesis and collection of data by experiment or observation and abstracting the hypothesis based on the experience which uses the data. The statistical methodology plays an important role in this process. The method which acquires a data becomes an initial process of abstraction and a survey research using structured questionnaires is a basic tool. After the data is acquired, the high-class statistical techniques such as the regression analysis and the linear structural equation model are used to abstract a hypothesis. By the way, from time to time the concepts which have become abstractive do not help us to understand an actual phenomena, rather it is need to extract some knowledge from questions themselves. In this article, we review the well known statistical methods providing the ways of finding core questions which possibly answer a researcher wants to know. We deal with course evaluation data as an example and try to set up the strategy for improving course evaluation.

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An Analysis of Effects of Differential Coinsurance Policy and Utilization of Outpatients Care by Types of Medical Institutions (종별 의료기관 외래 경증질환 약제비 본인부담 차등정책 효과분석)

  • Park, Yoon-Sung;Kim, Jin Suk
    • Health Policy and Management
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    • v.27 no.2
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    • pp.128-138
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    • 2017
  • Background: The purpose of this study is to analyze the effects of differential coinsurance policy on prescription drug coverage of outpatients by types of medical institutions. Methods: In this study, we used a sample cohort database of the National Health Insurance Service and frequency analysis and marginal logistic regression model using generalized estimating equation were used for statistical analysis. Results: The summary on the major research is followed. First, about 16% of patients who used only tertiary or general hospital due to 52 ambulatory care sensitive conditions before policy implementation moved to hospitals and clinics. However, about 57% of them still use tertiary or general hospital. Second, the factors influencing the utilization of hospitals and clinics after the implementation of the policy were gender, age, and income level. As a result, the policy is effective to reduce the medical use of outpatient mental patients in tertiary or general hospital, but the effect is not significant. Conclusion: Therefore, in order to achieve the purpose of the policy for establishing the health care delivery system, it is necessary to adjust the co-payment so as to feel the burden on the co-payment when the outpatient for 52 ambulatory care sensitive conditions is used at the tertiary or general hospital.

The Rating of Korean Basketball League Teams in 2006-2007 Season: Taking Account of Home-Court Advantage (홈팀의 이점을 고려한 KBL 2006-2007 시즌 경기력 평가)

  • Lee, Seung-Chun;Byun, Jong-Seok
    • Communications for Statistical Applications and Methods
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    • v.15 no.5
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    • pp.687-695
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    • 2008
  • It is widely known that the home advantage plays an important factor for determining victory or defeat in sport leagues. Thus a ranking system of sport league should take account of the home advantage as a key factor. Various statistical models are studied to rate the Korean Basketball league teams in 2006-2007 season. Among them, the model equation provided by Harville and Smith (1994) is useful for constructing two ranking systems. Both systems give quite reasonable quantifications of the team's ability and the home advantage.

A study on the factors affecting the life satisfaction of the elderly (노인의 생활전반 만족에 영향을 미치는 요인에 관한 연구)

  • Choi, Hyun-Seok;Ha, Jeong-Cheol
    • Journal of the Korean Data and Information Science Society
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    • v.23 no.1
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    • pp.131-142
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    • 2012
  • Since Korea is moving towards the aged society, increasing is the social attention on overall life satisfaction of the elderly. The purpose of this study is to find the factors affecting the life satisfaction of the elderly among demographic characteristics of aged people, categorized satisfactions and sources of income, based on the 2008 national survey data of the actual living condition of the elderly and welfare need. We found that many factors have significant impact on the life satisfaction of the elderly, such as demographic characteristics, the level of physical and mental health, the economic level.

The Impacts of Social Support on Industrial Injured Workers' Self-rated Health (산업재해 근로자의 사회적 지지가 주관적 건강에 미치는 영향)

  • Kim, Ji Eun;Hahm, Myung-il
    • Health Policy and Management
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    • v.32 no.2
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    • pp.180-189
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    • 2022
  • Background: Social support contributes directly and indirectly to maintaining physical, mental, and social well-being. The aim of the study was to identify the impact of social support on self-rated health among Korean industrial accident workers. Methods: This study used data from the panel study of workers' compensation insurance (PSWCI). The final subjects were 2,759 workers who responded to a 2018 to 2020 PSWCI. Social support was defined as social contact with friends, neighbors, family, and social participation activities like religious activity, social activity, and club activity. Multivariate logistic regression analysis was performed to investigate causal relationships between social support and self-rated health using a generalized estimating equation model. Results: Proportion of workers' good self-rated health steadily increased (2018: n=1,447, 63.2%; 2019: n=1,542, 66.2%; 2020: n=1,653, 67.3%). Higher levels of social contacts with friend (worse: reference; same: β=0.442) and higher levels of social activity (yes: reference; no: β=-0.173) were especially associated with good self-rated health. Conclusion: This study confirmed social support positively influenced self-rated health among the self-rated health of industrial injured workers. The results of this study suggested that recovery policies that the government served should include programs enhancing social support for improving health among industrial injured workers.

Probability of Early Retirement Among Emergency Physicians

  • Shin, Jaemyeong;Kim, Yun Jeong;Kim, Jong Kun;Lee, Dong Eun;Moon, Sungbae;Choe, Jae Young;Lee, Won Kee;Lee, Hyung Min;Cho, Kwang Hyun
    • Journal of Preventive Medicine and Public Health
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    • v.51 no.3
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    • pp.154-162
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    • 2018
  • Objectives: Early retirement occurs when one's job satisfaction suffers due to employment mismatch resulting from factors such as inadequate compensation. Medical doctors report high levels of job stress and burnout relative to other professionals. These levels are highest among emergency physicians (EPs), and despite general improvements in their working conditions, early retirement continues to become more common in this population. The purpose of this study was to identify the factors influencing EPs intention to retire early and to develop a probability equation for its prediction. Methods: A secondary analysis of data from the 2015 Korean Society of Emergency Physicians Survey was performed. The variables potentially influencing early retirement were organized into personal characteristics, extrinsic factors, and intrinsic factors. Logistic regression analysis was performed to identify risk factors and to develop a probability equation; these findings were then arranged in a nomogram. Results: Of the 377 survey respondents included in the analysis, 48.0% intended to retire early. Risk factors for early retirement included level of satisfaction with the specialty and its outlook, slanderous reviews, emergency room safety, health status, workload intensity, age, and hospital type. Intrinsic factors (i.e., slanderous reviews and satisfaction with the specialty and its outlook) had a stronger influence on early retirement than did extrinsic factors. Conclusions: To promote career longevity among EPs, it is vital to improve emergency room safety and workload intensity, to enhance medical professionalism through a stronger vision of emergency medicine, and to strengthen the patient-doctor relationship.