• 대한예방의학회:학술대회논문집
• /
• 대한예방의학회 1998년도 제50차 추계 학술대회 연제집
• /
• pp.196-197
• /
• 1998

• Communications for Statistical Applications and Methods
• /
• 제6권2호
• /
• pp.601-610
• /
• 1999

Crossover design is officially except for special occasions recommended by KFDA and FDA for assessing Bioequivalence between two drugs one for reference and the other for innovator. Such design is regarded as a special case of latin square split-polt or repeated measurement design and its main difference with other designing methods is that each subject in an experiment is exposed two drugs in sequence. Therefore general statistical analysis is not suitable since the model for this experiment includes carryover effect in addition to period and sequence effect. in this paper analysis for crossover model with two drugs and its interpretation are mainly discussed and an example is given for illustration.

• 복식문화연구
• /
• 제14권3호
• /
• pp.457-468
• /
• 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.

• Asia Marketing Journal
• /
• 제11권3호
• /
• pp.151-165
• /
• 2009

본 사례는 Crossover Utility Vehicle (CUV)의 선구자인 기아자동차 SOUL이 혁신적인 제품전략을 통하여 어떻게 새로운 시장을 개척하였는지를 분석하고 있다. 지금까지 대부분의 자동차 제조업체들은 전통적인 시장세분화 기준에 치중하여, 여러 소비자 계층들을 동시에 만족시킬 수 있는 신제품 개발의 기회를 놓치고 있었다. 기아자동차 SOUL은 여러 소비자 계층을 만족시킬 수 있는 제품에 대한 기회를 포착하고, 기존 소비자 계층별 가치를 통합적으로 제공하여 새로운 시장을 열었다. 본 사례는 포화상태에 있는 자동차 산업에서 혁신적인 제품전략을 통해 신시장을 개척하는 과정을 잘 보여주고 있다. 기아자동차 SOUL의 혁신적 제품전략을 크게 디자인 혁신, CUV 시장 개척, 고객을 위한 맞춤서비스 제공, 그리고 기능 혁신의 4가지 축으로 설명하고 있다. 기아자동차 SOUL의 혁신적인 제품전략은 블루오션 개척을 계획하고 있는 많은 기업에게 의미 있는 시사점을 제공해 준다.

• 응용통계연구
• /
• 제13권2호
• /
• pp.265-274
• /
• 2000

대기오염 자료와 사망자수 자료를 이용하여 대기중 총분진이 사망자수에 미치는 영향을 1996~1997년 서울 자료를 이용하여 분석하였다. 대기오염 자료에서 보이는 강한 계절성과 장기간의 경향 그리고 기온과 습도의 비선형관계를 고려하여 일반화 부가모형(generalized additive model)을 사용하였고, 그 결과 대기중 총분진 100$\mu$g/㎥ 증가시 초과사망자는 3%(95% 신뢰구간 : 0.8-5.2)로 추정되었다. 사례-교차연구(case-crossover study)의 결과를 보면 한 방향(후향적, 전향적)으로의 대조기간 설정 방법은 편향된 추정치를 주었고 양방향 방법은 회귀계수의 추정치는 일반화 부가모형과 거의 같은 결과를 주었지만 표준오차는 상대적으로 큰 값을 주었다. 이상에서 볼 때 대기오염 자료의 분석과 같이 계절성이 큰 자료에서는 사례-교차 연구를 적용할 때 주의가 요구됨을 알 수 있었다.

• Journal of Preventive Medicine and Public Health
• /
• 제36권1호
• /
• pp.47-53
• /
• 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.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1997년도 추계학술대회 논문집 학회본부
• /
• pp.257-260
• /
• 1997

This paper designs the optimal PID controller for load frequency control on 2-area power system. Genetic algorithm is utilized to optimize parameters of PID controller which is applied to power system. Using two-point crossover, uniform crossover and one-point crossover, Search performance of genetic algorithm with each crossover method is considered. In case of load variation in 1-area, the dynamic characteristic of power system is considered. The simulation results show that the proposed PID controller is better control performance than PID controller using Ziegler-Nichols method.

• 대한예방의학회:학술대회논문집
• /
• 대한예방의학회 2000년도 제52차 추계학술대회 연제집
• /
• pp.112-113
• /
• 2000

• Journal of Preventive Medicine and Public Health
• /
• 제45권4호
• /
• pp.219-226
• /
• 2012

Objectives: To evaluate the risk of fractures related with zolpidem in elderly insomnia patients. Methods: Health claims data on the entire South Korean elderly population from January 2005 to June 2006 were extracted from the Health Insurance Review and Assessment Service database. We applied a case-crossover design. Cases were defined as insomnia patients who had a fracture diagnosis. We set the hazard period of 1 day length prior to the fracture date and four control periods of the same length at 5, 10, 15, and 20 weeks prior to the fracture date. Time independent confounding factors such as age, gender, lifestyle, cognitive function level, mobility, socioeconomic status, residential environment, and comorbidity could be controlled using the case-crossover design. Time dependent confounding factors, especially co-medication of patients during the study period, were adjusted by conditional logistic regression analysis. The odds ratios and their 95% confidence intervals (CIs) were estimated for the risk of fracture related to zolpidem. Results: One thousand five hundred and eight cases of fracture were detected in insomnia patients during the study period. In our data, the use of zolpidem increased the risk of fracture significantly (adjusted odds ratio [aOR], 1.72; 95% CI, 1.37 to 2.16). However, the association between benzodiazepine hypnotics and the risk of fracture was not statistically significant (aOR, 1.00; 95% CI, 0.83 to 1.21). Likewise, the results were not statistically significant in stratified analysis with each benzodiazepine generic subgroup. Conclusions: Zolpidem could increase the risk of fracture in elderly insomnia patients. Therefore zolpidem should be prescribed carefully and the elderly should be provided with sufficient patient education.

• Journal of Chest Surgery
• /
• 제54권1호
• /
• pp.53-58
• /
• 2021

Background: We aimed to investigate the characteristics of primary spontaneous pneumothorax (PSP) in adolescents and to analyze the relationship between the occurrence of PSP and air pollutants. Methods: Data pertaining to age, sex, body mass index, smoking status, initial pneumothorax volume, presence of bullae, treatment methods, and city of residence were retrospectively obtained from January 2010 to December 2014. We investigated the association between short-term exposure to air pollutants (SO2, NO2, O3, CO, and PM10) and the occurrence of PSP using a case-crossover design with conditional logistic regression. Results: We collected information from 598 patients who were admitted for PSP, with a mean follow-up duration of 62.9 months. The majority (91.1%) of the patients were male. In the case-crossover design, conditional logistic regression showed that no air pollutant was associated with the occurrence of pneumothorax. The results were consistent across all city subgroups (Anyang, Gunpo, Uiwang, and Gwacheon). Conclusion: In our study, the incidence rate of pneumothorax was 153.8 per 100,000 person-years in male adolescents and 16.7 per 100,000 person-years in female adolescents. The case-crossover design showed that PSP in adolescents is unlikely to be related to air pollution.