• Title/Summary/Keyword: Imputation method

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Lung Function Trajectory Types in Never-Smoking Adults With Asthma: Clinical Features and Inflammatory Patterns

  • Kim, Joo-Hee;Chang, Hun Soo;Shin, Seung Woo;Baek, Dong Gyu;Son, Ji-Hye;Park, Choon-Sik;Park, Jong-Sook
    • Allergy, Asthma & Immunology Research
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    • v.10 no.6
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    • pp.614-627
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    • 2018
  • Purpose: Asthma is a heterogeneous disease that responds to medications to varying degrees. Cluster analyses have identified several phenotypes and variables related to fixed airway obstruction; however, few longitudinal studies of lung function have been performed on adult asthmatics. We investigated clinical, demographic, and inflammatory factors related to persistent airflow limitation based on lung function trajectories over 1 year. Methods: Serial post-bronchodilator forced expiratory volume (FEV) 1% values were obtained from 1,679 asthmatics who were followed up every 3 months for 1 year. First, a hierarchical cluster analysis was performed using Ward's method to generate a dendrogram for the optimum number of clusters using the complete post-FEV1 sets from 448 subjects. Then, a trajectory cluster analysis of serial post-FEV1 sets was performed using the k-means clustering for the longitudinal data trajectory method. Next, trajectory clustering for the serial post-FEV1 sets of a total of 1,679 asthmatics was performed after imputation of missing post-FEV1 values using regression methods. Results: Trajectories 1 and 2 were associated with normal lung function during the study period, and trajectory 3 was associated with a reversal to normal of the moderately decreased baseline FEV1 within 3 months. Trajectories 4 and 5 were associated with severe asthma with a marked reduction in baseline FEV1. However, the FEV1 associated with trajectory 4 was increased at 3 months, whereas the FEV1 associated with trajectory 5 was persistently disturbed over 1 year. Compared with trajectory 4, trajectory 5 was associated with older asthmatics with less atopy, a lower immunoglobulin E (IgE) level, sputum neutrophilia and higher dosages of oral steroids. In contrast, trajectory 4 was associated with higher sputum and blood eosinophil counts and more frequent exacerbations. Conclusions: Trajectory clustering analysis of FEV1 identified 5 distinct types, representing well-preserved to severely decreased FEV1. Persistent airflow obstruction may be related to non-atopy, a low IgE level, and older age accompanied by neutrophilic inflammation and low baseline FEV1 levels.

Development of Machine Learning Based Precipitation Imputation Method (머신러닝 기반의 강우추정 방법 개발)

  • Heechan Han;Changju Kim;Donghyun Kim
    • Journal of Wetlands Research
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    • v.25 no.3
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    • pp.167-175
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    • 2023
  • Precipitation data is one of the essential input datasets used in various fields such as wetland management, hydrological simulation, and water resource management. In order to efficiently manage water resources using precipitation data, it is essential to secure as much data as possible by minimizing the missing rate of data. In addition, more efficient hydrological simulation is possible if precipitation data for ungauged areas are secured. However, missing precipitation data have been estimated mainly by statistical equations. The purpose of this study is to propose a new method to restore missing precipitation data using machine learning algorithms that can predict new data based on correlations between data. Moreover, compared to existing statistical methods, the applicability of machine learning techniques for restoring missing precipitation data is evaluated. Representative machine learning algorithms, Artificial Neural Network (ANN) and Random Forest (RF), were applied. For the performance of classifying the occurrence of precipitation, the RF algorithm has higher accuracy in classifying the occurrence of precipitation than the ANN algorithm. The F1-score and Accuracy values, which are evaluation indicators of the classification model, were calculated as 0.80 and 0.77, while the ANN was calculated as 0.76 and 0.71. In addition, the performance of estimating precipitation also showed higher accuracy in RF than in ANN algorithm. The RMSE of the RF and ANN algorithms was 2.8 mm/day and 2.9 mm/day, and the values were calculated as 0.68 and 0.73.

A study of Liability for LMO and Biomedicine (LMO에 대한 손해배상책임 - 바이오신약을 중심으로)

  • Moon, Sang-Hyuk
    • The Korean Society of Law and Medicine
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    • v.12 no.1
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    • pp.43-67
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    • 2011
  • Humankind history is faced with one gigantic turning point due to development of Living genetically Modified Organisms. Food production by means of LMO is on the acceleration in an effort to solve the shortage of food problems. Food is also used as alternative energy source. Use of LMO product is not only limited to food and energy, but is actively utilized in various fields of medicines. This paper is first to check out the state of biomedicine developed and associated problems from industries that use LMO, after which we made an attempt on legislative approach to find out means of relief, through examples of such laws legislated for the sufferer from the adverse effect of the biomedicine. As for the liable subject to bear the responsibility for compensatory damage in a way of relieving the victim owing to adverse effect of biomedicine, those who manufactured and sold biomedicine and who are related to the damage to the victim due to the accident and medical doctors and pharmacists who prescribe and administer the medicine in question have been looked into. Accidents involving medicines and medical supplies could take place without reason for imputation on part of the liable subjects or fault of the victim, in which case the victim can't receive damage compensation from any of both parties. When such accidents happened turn out to be no fault accidents, introduction of damage relief measures might have to be reviewed against side effects of medicine and medical supplies as no fault compensation in order for actual relief to be possible. Talking about technicality of legislation, we can suggest a method of strengthening the accountability of manufacturer for stereotypical agenda on biomedicines by newly legislating special regulation with an issue that resists claim on risks associated with the development of medicine and incorporating the same into Manufactured Product Liability Law. After all, when an accident happens associated with biomedicine, the damage will be done to the consumer. And the consumer will be exposed to fatal danger even without the time to cope with potential risks associated with medicine and medical supplies they take. Therefore, it is necessary to protect the potential victim by having the manufacturer of biomedicines bear the liability of medical risks.

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Estimation of the Percent of the Vote by Adjustment of Voter Turnout in Election Polls (선거여론조사에서 투표율 반영을 통한 득표율 추정)

  • Kim, Jeonghoon;Han, Sang-Tae;Kang, Hyuncheol
    • Journal of the Korean Data Analysis Society
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    • v.20 no.6
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    • pp.2873-2881
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    • 2018
  • It is very important to obtain objective and credible information through election polls in order to contribute to the correct voting behavior of the voters or to establish appropriate election strategies for candidates or political parties. Therefore, many related organizations such as political parties, media organizations, and research institutions have been making efforts to improve the accuracy of the results of the polls and the election prediction. Kim et al. (2017) analyzed whether the non-response group responded that there is no support candidate in the election survey to increase the accuracy of the estimation of the vote rate. As a result, it has been confirmed that the accuracy of the estimation of the vote rate can be significantly improved by performing an appropriate classification on the non-response layer. In this study, we propose a method to estimate the turnout by each strata (sex, age group) under the condition that the total turnout rate is given for a specific district (region) and propose a procedure to predict the vote rate by reflecting the turnout. In addition, case studies were conducted using data gathered through telephone interviews for the 20th National Assembly elections in 2016.