• Title/Summary/Keyword: Case-crossover study

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A Case Study on Crossover Coordination Applied in Fashion Collection since 1996 (1996년 이후 패션 콜렉션에 나타난 크로스오버 코디네이션에 관한 연구)

  • Kim Chil-Soon;Yoo Hee-Jung
    • The Research Journal of the Costume Culture
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    • v.14 no.3 s.62
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    • pp.457-468
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    • 2006
  • The purpose of this study was to understand fashion trend and characteristics by finding out the influences of crossover on modern fashion coordination through the identification of crossover coordination trend and characteristics. With a review of the literature, this study analyzed crossover coordination according to the types of expression methodology, periodical changes and designer's tastes that appeared through the collections of the six representative designers from 1996 to 2004. The results of this study were as follows. As a result of analysis of our sources, we realized that crossover coordination was shown most frequently in 1997 and Christian Dior was the designer who used crossover coordination most frequently. Among lots of crossover coordination cases, most of the cases are the coordination with different materials. In our results, trends of crossover coordination in materials appeared again about every five years cycle. Christian Dior combined different elements through silhouette and material, Dolce & Gabbana combined images and Jean Paul Gaultier combined different elements in the aspect of purpose and wearing configuration.

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Innovative Product Strategy of KIA SOUL - Attract customers' soul - (기아자동차 SOUL의 혁신적인 제품전략 - 소비자의 soul을 움직이다 -)

  • Lee, Doo-Hee;Lee, Jong-Ho;Jeon, Ki Heung
    • Asia Marketing Journal
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    • v.11 no.3
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    • pp.151-165
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    • 2009
  • The objective of this case study is to analyze how effectively KIA SOUL, which is a leading Crossover Utility Vehicle (CUV) brand, has created a new market space through innovative product strategy. Up until now, most car manufacturers have focused only on the traditional product market segments missing out on the opportunity of the crossover segment market. KIA SOUL found a new market space by identifying the high crossover utility demand and filling the gap between the current product category values and the emerging crossover product category values. This case study illustrates that an innovative product strategy can be effectively employed to create a new market space in the saturated car manufacturing industry. The case summarizes that the innovative product strategy of KIA SOUL is comprised of four primary pillars: design innovation, market frontier in CUV, the first company to launch customizing service brand-TUON, and functional innovation. The KIA SOUL case study provides valuable insights and implications for many other companies that are planning to find "blue oceans" for their own business.

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$PM_{10}$ Exposure and Non-accidental Mortality in Asian Populations: A Meta-analysis of Time-series and Case-crossover Studies

  • Park, Hye Yin;Bae, Sanghyuk;Hong, Yun-Chul
    • Journal of Preventive Medicine and Public Health
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    • v.46 no.1
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    • pp.10-18
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    • 2013
  • Objectives: We investigated the association between particulate matter less than $10{\mu}m$ in aerodynamic diameter ($PM_{10}$) exposure and non-accidental mortality in Asian populations by meta-analysis, using both time-series and case-crossover analysis. Methods: Among the 819 published studies searched from PubMed and EMBASE using key words related to $PM_{10}$ exposure and non-accidental mortality in Asian countries, 8 time-series and 4 case-crossover studies were selected for meta-analysis after exclusion by selection criteria. We obtained the relative risk (RR) and 95% confidence intervals (CI) of non-accidental mortality per $10{\mu}g/m^3$ increase of daily $PM_{10}$ from each study. We used Q statistics to test the heterogeneity of the results among the different studies and evaluated for publication bias using Begg funnel plot and Egger test. Results: Testing for heterogeneity showed significance (p<0.001); thus, we applied a random-effects model. RR (95% CI) per $10{\mu}g/m^3$ increase of daily $PM_{10}$ for both the time-series and case-crossover studies combined, time-series studies relative risk only, and case-crossover studies only, were 1.0047 (1.0033 to 1.0062), 1.0057 (1.0029 to 1.0086), and 1.0027 (1.0010 to 1.0043), respectively. The non-significant Egger test suggested that this analysis was not likely to have a publication bias. Conclusions: We found a significant positive association between $PM_{10}$ exposure and non-accidental mortality among Asian populations. Continued investigations are encouraged to contribute to the health impact assessment and public health management of air pollution in Asian countries.

An analysis of air apollution and daily mortality (대기중 총분진과 사망자수에 관한 분석)

  • Kim, Ho
    • The Korean Journal of Applied Statistics
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    • v.13 no.2
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    • pp.265-274
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    • 2000
  • Relationship between the daily mortality and total suspended particulate(TSP) for the period of 1996-1997 was examined in Seoul, Korea. Generalized additive model was adapted for the analysis to allow the seasonality and long-term time effect in the air pollution and the nonlinear relationships with weather variables such as air temperature and relative humidity. An increase of 100 Ji9/m') TSP corresponds to 0.8-5.2 percent increase of the daily mortality Unidirectional (prospective and retrospective) case-crossover design results in large bias of the estimates. Bidirectional method gives relatively unbiased estimates but the standard errors are larger Case-crossover design should be used with caution in the situation where the data have seasonal trends like air pollution study.

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Incorporating Genetic Operators into Optimizing Highway Alignments (도로선형최적화를 위한 유전자 연산자의 적용)

  • Kim, Eung-Cheol
    • Journal of Korean Society of Transportation
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    • v.22 no.2 s.73
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    • pp.43-54
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    • 2004
  • This study analyzes characteristics and applicability of genetic algorithms and genetic operators to optimize highway alignments. Genetic algorithms, one of artificial intelligence techniques, are fast and efficient search algorithms for generating, evaluation and finding optimal highway alignment alternatives. The performance of genetic algorithms as an optimal search tool highly depends on genetic operators that are designed as a problem-specific. This study adopts low mutation operators(uniform mutation operator, straight mutation operator, non-uniform mutation operator whole non-uniform mutation operator) to explore whole search spaces, and four crossover operators(simple crossover operator, two-point crossover operator, arithmetic crossover operator, heuristic crossover operator) to exploit food characteristics of the best chromosome in previous generations. A case study and a sensitivity analysis have shown that the eight problem-specific operators developed for optimizing highway alignments enhance the search performance of genetic algorithms, and find good solutions(highway alignment alternatives). It has been also found that a mixed and well-combined use of mutation and crossover operators is very important to balance between pre-matured solutions when employing more crossover operators and more computation time when adopting more mutation operators.

Associations between Air Pollution and Asthma-related Hospital Admissions in Children in Seoul, Korea: A Case-crossover Study (환자교차 설계 방법을 적용한 소아천식 입원에 대한 도시 대기오염의 급성영향평가)

  • Lee, Jong-Tae
    • Journal of Preventive Medicine and Public Health
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    • v.36 no.1
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    • pp.47-53
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    • 2003
  • Objectives : I used a case-crossover design to investigate the association between air pollution, and hospital admissions for asthmatic children under the age of 15 years in Seoul, Korea Methods : I estimated the changes in the levels of hospitalization risk from theinterquartile (IQR) increase in each pollutant concentrations, using conditional logistic regression analyses, with controls for weather information. Results : Using bidirectional control sampling, the results from a conditional logistic regression model, with controls for weather conditions, showed the estimated relative risk of hospitalization for asthma among children to be 1.04 (95% confidence interval (CI), 1.01-1.08) for particulate matter with an aerodynamic diameter less than or equal to 10m (IQR=40.4ug/m3); 1.05 (95% CI, 1.00- 1.09) for nitrogen dioxide (IQR=14.6ppb): 1.02 (95% CI,0.97-1.06) for sulfur dioxide (IQR=4.4ppb): 1.03 (95% CI, 0.99-1.08) for ozone (IQR=21.7ppb): and 1.03 (95% CI, 0.99-1.08) for carbon monoxide f10R=1.0ppm). Conclusions : This empirical analysis indicates the bidirectional control sampling methods, by design, would successfully control the confounding factors due to the long-term time trends of air pollution. These findings also support the hypothesis that air pollution at levels below the current ambient air quality standards of Korea is harmful to sensitive subjects, such as asthmatic children.

Application of Crossover Analysis-logistic Regression in the Assessment of Gene- environmental Interactions for Colorectal Cancer

  • Wu, Ya-Zhou;Yang, Huan;Zhang, Ling;Zhang, Yan-Qi;Liu, Ling;Yi, Dong;Cao, Jia
    • Asian Pacific Journal of Cancer Prevention
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    • v.13 no.5
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    • pp.2031-2037
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    • 2012
  • Background: Analysis of gene-gene and gene-environment interactions for complex multifactorial human disease faces challenges regarding statistical methodology. One major difficulty is partly due to the limitations of parametric-statistical methods for detection of gene effects that are dependent solely or partially on interactions with other genes or environmental exposures. Based on our previous case-control study in Chongqing of China, we have found increased risk of colorectal cancer exists in individuals carrying a novel homozygous TT at locus rs1329149 and known homozygous AA at locus rs671. Methods: In this study, we proposed statistical method-crossover analysis in combination with logistic regression model, to further analyze our data and focus on assessing gene-environmental interactions for colorectal cancer. Results: The results of the crossover analysis showed that there are possible multiplicative interactions between loci rs671 and rs1329149 with alcohol consumption. Multifactorial logistic regression analysis also validated that loci rs671 and rs1329149 both exhibited a multiplicative interaction with alcohol consumption. Moreover, we also found additive interactions between any pair of two factors (among the four risk factors: gene loci rs671, rs1329149, age and alcohol consumption) through the crossover analysis, which was not evident on logistic regression. Conclusions: In conclusion, the method based on crossover analysis-logistic regression is successful in assessing additive and multiplicative gene-environment interactions, and in revealing synergistic effects of gene loci rs671 and rs1329149 with alcohol consumption in the pathogenesis and development of colorectal cancer.

Transient Effects the Risk of Occupational Injuries as an Acute Events : a Case-crossover Study (환자-교차 대조군 연구를 적용한 산업재해 발생의 단기적 영향 요인)

  • Jeong, Seon-A;Won, Jong-Uk;Roh, Jae-Hoon;Lee, Jong-Tae
    • Journal of Preventive Medicine and Public Health
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    • v.34 no.1
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    • pp.35-40
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    • 2001
  • Objectives : To elucidate the transient effects on the risk of occupational injuries as acute events and establish so alternative proposal. Methods : The study population comprised a total of 302 workers randomly selected from applications for occupational injury compensation reported to the Inchon local labor office from January 1. 1999 to December 31. A case-crossover design, where each case serves its own control, was applied to this study. Through a telephone interview, workers provided useful data concerning five job related stressful events such as company transfer, work load change, overtime work, exchange duty, and work-part transfer. They were asked whether there were stressful events within a week of the occurrence of injury and the degree of stress. Exposure status from one year prior was used as control information. In the end, the data provided by 158 of selected persons was used for the analysis based on the quality of the data provided by the participants. A conditional logistic regression was used to discover the transient effects on the risk of occupational injuries as acute events. Results : The effects a company transfer and work load change on occupational injury was statistically significant on the risk of occupational Injuries as an acute event(RR=5.5, 95% CI=2.501-12.428; RR=3.1, 95% CI=1.963-5.017, respectively). Other stressful events were found to elevate the risk factor for the occurrence of occupational jujury, but were not significant. Conclusions : Our results suggested that transient stressful events elevated the risk factor for the occurrence of occupational injury.

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Air pollution and hospital admissions for chronic obstructive pulmonary disease: are their potentially sensitive groups?

  • Tsai, Shang-Shyue;Yang, Ya-Hui;Liou, Saou-Hsing;Wu, Trong-Neng;Yang, Chun-Yuh
    • Advances in environmental research
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    • v.1 no.1
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    • pp.57-68
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    • 2012
  • Recent studies showed that air pollution is a risk factor for hospitalization for chronic obstructive pulmonary disease (COPD). However, there is limited evidence to suggest which subpopulations are at higher risk from air pollution. This study was undertaken to examine the modifying effect of specific secondary diagnosis (including hypertension, diabetes, pneumonia, congestive heart failure) on the relationship between hospital admissions for COPD and ambient air pollutants concentrations. Hospital admissions for COPD and ambient air pollution data for Taipei were obtained for the period from 1999-2009. The relative risk of hospital admissions for COPD was estimated using a case-crossover approach. None of the secondary diagnosis we examined showed much evidence of effect modification.