• Title/Summary/Keyword: Case-crossover design

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A Study on the Blending Color in Karim Rashid's Works (카림 라시드의 작품에 나타난 블렌딩 색채에 관한 연구)

  • Kim, Sun-Young
    • Korean Institute of Interior Design Journal
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    • v.20 no.4
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    • pp.155-162
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    • 2011
  • In order to pursue the traces of truth, boundaries set by man for convenience were crossed or Integrated leading to the discovery of new paradigms. Such phenomena including collaboration, convergence, crossover and etc. are expressed in various forms across the society and culture. In particular, development of digital technology is moving away from its previous color based on scientific, statistical and quantitative perspective by using diverse variables. Also, as the borderlines of genres become increasingly more ambiguous, various concepts of color blending developed rapidly. Thus These chaosmos-like color blending have created new contents. This research aims to understand the principle of color blending in Karim Rashid's work, which advocates the world of design in diverse fields from industrial products to architecture. The principle of color blending such as information change, source color and destination color, interaction, and etc. makes it possible to extract the expressed element and method of color blending. Meanwhile, the features of color blending such as integrated space and time, vague form, and narrative genre can be inferred from case analysis.

Optimal design using genetic algorithm with nonlinear elastic analysis

  • Kim, Seung-Eock;Song, Weon-Keun;Ma, Sang-Soo
    • Structural Engineering and Mechanics
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    • v.17 no.5
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    • pp.707-725
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    • 2004
  • An optimal design method with nonlinear elastic analysis is presented. The proposed nonlinear elastic method overcomes the drawback of the conventional LRFD method that accounts for nonlinear effect by using the moment amplification factors of $B_1$ and $B_2$. The genetic algorithm used is a procedure based on Darwinian notions of survival of the fittest, where selection, crossover, and mutation operators are employed to look for high performance ones among sections in the database. They are satisfied with the constraint functions and give the lightest weight to the structure. The objective function taken is the total weight of the steel structure and the constraint functions are strength, serviceability, and ductility requirement. Case studies of a planar portal frame, a space two-story frame, and a three-dimensional steel arch bridge are presented.

Effects of Air Pollution on Asthma in Seoul: Comparisons across Subject Characteristics (서울지역 대기오염이 천식에 미치는 급성영향: 연구대상의 특성에 따른 비교)

  • Kim, Sun-Young;Kim, Jai-Yong;Kim, Ho
    • Journal of Preventive Medicine and Public Health
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    • v.39 no.4
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    • pp.309-316
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    • 2006
  • Objectives: Korean epidemiological studies have used reduced samples according to the subject's characteristics, such as the health services provided, the historical note with asthma, and age, to examine the acute effect of air pollution on asthma using the Korean National Health Insurance records. However, there have been few studies on whether the effects shown in these reduced samples are different from those of all samples. This study compared the effects of air pollution on asthma attacks in three reduced samples with those of entire samples. Methods: The air pollution data for $PM_{10},\;CO,\;SO_2,\;NO_2,\;and\;O_3$, and weather conditions including temperature, relative humidity, and air pressure in Seoul, 2002, were obtained from outdoor monitoring stations in Seoul. The emergency hospital visits with an asthma attack in Seoul, 2002 were extracted from the Korean National Health Insurance records. From these, the reduced samples were created by health service, historical notes with asthma, and age. A case-crossover design was adopted and the acute effects of air pollution on asthma were estimated after adjusting for weather, time trend, and seasonality. The model was applied to each reduced sample and the entire sample. Results: With respect to the health service, the effects on outpatients were similar to those for the total sample but were different for inpatients. These similar effect sizes were also observed in the reduced samples according to the historical note with asthma and age. The relative risks of $PM_{10},\;CO,\;SO_2,\;NO_2,\;and\;O_3$, among the reduced and entire samples were 1.03, 1.04-1.05, 1.02-1.03, 1.04-1.06, and 1.10-1.17, respectively. Conclusions: There was no clear evidence to show a difference between the reduced samples and the entire samples.

Comparison of Endotracheal Intubation in Difficult Postures by Using the SALT(Supraglottic Airway Laryngopharyneal Tube)

  • Yun, Seong-Woo
    • Journal of the Korea Society of Computer and Information
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    • v.25 no.12
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    • pp.227-233
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    • 2020
  • The purpose of this study is to compare the speed, confidence, and ease of endotracheal intubation in a difficult posture by using the SALT(Supraglottic Airway Laryngopharyngeal Tube), and a direct laryngoscope to improve the ability to implement professional airway management. The subject of the study was an experimental study by a randomized crossover design, targeting 30 first-class emergency medical technicians working in J-do fire station, and the SPSS 20.0 version was used for data analysis. The endotracheal intubation by using SALT showed a significant difference in speed compared to endotracheal intubation by using a direct laryngoscope(p<.001), and also showed a significant difference in confidence and ease(p<.001). If it is difficult to endotracheal intubation by direct laryngoscope, or in the case of trauma patients, if SALT is used, safe and rapid intubation will be possible. In addition, to improve the efficiency of professional airway management, it is believed that the introduction of SALT in domestic sites is necessary.

Comparison of Endotracheal Intubation to Transfer - A Study of Simulation Using the SALT - (이송 중 기관내 삽관의 효율성 비교 - SALT를 이용한 시뮬레이션 연구 -)

  • Yun, Seong-Woo;Jung, Jun-Ho;Lee, Hyo-Ju;Choi, Mi-Young
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2022.10a
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    • pp.300-302
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    • 2022
  • The purpose of this study is to compare the speed, confidence, and ease of endotracheal intubation in a transfer posture by using the SALT(Supraglottic Airway Laryngopharyngeal Tube), and a direct laryngoscope to improve the ability to implement professional airway management. The subject of the study was an experimental study by a randomized crossover design, targeting 28 first-class emergency medical technicians working in J-do fire station, and the SPSS 20.0 version was used for data analysis. The endotracheal intubation by using SALT showed a significant difference in speed compared to endotracheal intubation by using a direct laryngoscope(p<.001), and also showed a significant difference in confidence and ease(p<.001). If it is transfer to endotracheal intubation by direct laryngoscope, or in the case of transfer patients, if SALT is used, safe and rapid intubation will be possible.

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Errors in Estimated Temporal Tracer Trends Due to Changes in the Historical Observation Network: A Case Study of Oxygen Trends in the Southern Ocean

  • Min, Dong-Ha;Keller, Klaus
    • Ocean and Polar Research
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    • v.27 no.2
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    • pp.189-195
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    • 2005
  • Several models predict large and potentially abrupt ocean circulation changes due to anthropogenic greenhouse-gas emissions. These circulation changes drive-in the models-considerable oceanic oxygen trend. A sound estimate of the observed oxygen trends can hence be a powerful tool to constrain predictions of future changes in oceanic deepwater formation, heat and carbon dioxide uptake. Estimating decadal scale oxygen trends is, however, a nontrivial task and previous studies have come to contradicting conclusions. One key potential problem is that changes in the historical observation network might introduce considerable errors. Here we estimate the likely magnitude of these errors for a subset of the available observations in the Southern Ocean. We test three common data analysis methods south of Australia and focus on the decadal-scale trends between the 1970's and the 1990's. Specifically, we estimate errors due to sparsely sampled observations using a known signal (the time invariant, temporally averaged, World Ocean Atlas 2001) as a negative control. The crossover analysis and the objective analysis methods are for less prone to spatial sampling location biases than the area averaging method. Subject to numerous caveats, we find that errors due to sparse sampling for the area averaging method are on the order of several micro-moles $kg^{-1}$. for the crossover and the objective analysis method, these errors are much smaller. For the analyzed example, the biases due to changes in the spatial design of the historical observation network are relatively small compared to the tends predicted by many model simulations. This raises the possibility to use historic oxygen trends to constrain model simulations, even in sparsely sampled ocean basins.

Concept Optimization for Mechanical Product Using Genetic Algorithm

  • Huang Hong Zhong;Bo Rui Feng;Fan Xiang Feng
    • Journal of Mechanical Science and Technology
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    • v.19 no.5
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    • pp.1072-1079
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    • 2005
  • Conceptual design is the first step in the overall process of product design. Its intrinsic uncertainty, imprecision, and lack of information lead to the fact that current conceptual design activities in engineering have not been computerized and very few CAD systems are available to support conceptual design. In most of the current intelligent design systems, approach of principle synthesis, such as morphology matrix, bond graphic, or design catalogues, is usually adopted to deal with the concept generation, in which optional concepts are generally combined and enumerated through function analysis. However, as a large number of concepts are generated, it is difficult to evaluate and optimize these design candidates using regular algorithm. It is necessary to develop a new approach or a tool to solve the concept generation. Generally speaking, concept generation is a problem of concept synthesis. In substance, this process of developing design candidate is a combinatorial optimization process, viz., the process of concept generation can be regarded as a solution for a state-place composed of multi-concepts. In this paper, genetic algorithm is utilized as a feasible tool to solve the problem of combinatorial optimization in concept generation, in which the encoding method of morphology matrix based on function analysis is applied, and a sequence of optimal concepts are generated through the search and iterative process which is controlled by genetic operators, including selection, crossover, mutation, and reproduction in GA. Several crucial problems on GA are discussed in this paper, such as the calculation of fitness value and the criteria for heredity termination, which have a heavy effect on selection of better concepts. The feasibility and intellectualization of the proposed approach are demonstrated with an engineering case. In this work concept generation is implemented using GA, which can facilitate not only generating several better concepts, but also selecting the best concept. Thus optimal concepts can be conveniently developed and design efficiency can be greatly improved.

Climate Change and Health - A Systemic Review of Low and High Temperature Effects on Mortality (기후변화와 건강 - 저온과 고온이 사망에 미치는 영향에 관한 체계적 고찰)

  • Lim, Youn-Hee;Kim, Ho
    • Journal of Environmental Health Sciences
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    • v.37 no.6
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    • pp.397-405
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    • 2011
  • Objectives: The impact of climate change on the health has been of increasing concern due to a recent temperature increase and weather abnormality, and the research results of the impact varied depending on regions. We synthesized risk estimates of the overall health effects of low and high temperature taking account of the heterogeneity. Methods: A comprehensive literature search was conducted using PUBMED to identify journal articles of low and/or high temperature effects on mortality. The search was limited to the English language and epidemiological studies using time-series analysis and/or case-crossover design. Random-effect models in meta analysis were used to estimate the percent increase in mortality with $1^{\circ}C$ temperature decrease or increase with 95% confidence intervals (CI) in cold or hot days. Results: Twenty three studies were presented in two tables: 1) low temperature effects; 2) high temperature effects on mortality. The combined effects of low and high temperatures on total mortality were 2% (95% CI, 1-4%) per $1^{\circ}C$ decrease and 4% (95% CI, 2-5%) per $1^{\circ}C$ increase of temperature, respectively. Conclusions: This meta analysis found that both low and high temperatures affected mortality, and the magnitude of high temperature appeared to be stronger than that of low temperature.

Epidemiologic Methods and Study Designs for Investigating Adverse Health Effects of Ambient Air Pollution (대기오염의 건강 영향 평가를 위한 역학연구 설계 및 방법론)

  • Kim, Ho;Lee, Jong-Tae
    • Journal of Preventive Medicine and Public Health
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    • v.34 no.2
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    • pp.119-126
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    • 2001
  • Air pollution epidemiologic studies are intrinsically difficult because the expected effect size at general environmental levels is small, exposure and misclassification of exposure are common, and exposure is not selective to a specific pollutant. In this review paper, epidemiologic study designs and analytic methods are described, and two nationwide projects on air pollution epidemiology are introduced. This paper also demonstrates that possible confounding issues in time-series analysis can be resolved and the impact on the use of data from ambient monitoring stations may not be critical. In this paper we provide a basic understanding of the types of air pollution epidemiologic study designs that be subdivided by the mode of air pollution effects on human health (acute or chronic). With the improvements in the area of air pollution epidemiologic studies, we should emphasize that elaborate models and statistical techniques cannot compensate for inadequate study design or poor data collection.

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Nonlinear Elastic Optimal Design Using Genetic Algorithm (유전자 알고리즘을 이용한 비선형 탄성 최적설계)

  • Kim, Seung Eock;Ma, Sang Soo
    • Journal of Korean Society of Steel Construction
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    • v.15 no.2
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    • pp.197-206
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    • 2003
  • The optimal design method in cooperation with a nonlinear elastic analysis method was presented. The proposed nonlinear elastic method overcame the drawback of the conventional LRFD method this approximately accounts for the nonlinear effect caused by using the moment amplification factors of and. The genetic algorithm uses a procedure based on the Darwinian notions of the survival of the fittest, where selection, crossover, and mutation operators are used to look for high performance among the sections of the database. They satisfy constraint functions and give the lightest weight to the structure. The objective function was set to the total weight of the steel structure. The constraint functions were load-carrying capacities, serviceability, and ductility requirement. Case studies for a two-dimensional frame, a three-dimensional frame, and a three-dimensional steel arch bridge were likewise presented.