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상태공간 측정을 통한 AD HOC 네트워크의 최적화 연구
김현창,정석문,Kim, Hyun-Chang,Chung, Suk-Moon 한국군사과학기술학회 2005 한국군사과학기술학회지 Vol.8 No.4
In this paper, Ad-hoc network is a collection of mobile nodes without any wired infrastructure. Design of efficient routing protocols in ad-hoc network is a challenging issue. An AODV routing protocol for wireless ad hoc networks one that searches for and attempts to discover a route to some destination node. We propose a technique that reduce the number of Routing packet. Our technique use variable values reflecting the condition of network. This also contributes to improve throughput.
Development and Validation of Osteoporosis Risk-Assessment Model for Korean Men
김현창,오순민,송보미,남병호,이유미,문성환,김덕용,강대룡 연세대학교의과대학 2016 Yonsei medical journal Vol.57 No.1
Purpose: The aim of the present study was to develop an osteoporosis risk-assessment model to identify high-risk individuals among Korean men. Materials and Methods: The study used data from 1340 and 1110 men ≥50 years who participated in the 2009 and 2010 Korean National Health and Nutrition Examination Survey, respectively, for development and validation of an osteoporosis risk-assessmentmodel. Osteoporosis was defined as T score ≤-2.5 at either the femoral neck or lumbar spine. Performance of the candidate models and the Osteoporosis Self-assessment Tool for Asian (OSTA) was compared with sensitivity, specificity, and area under the receiver operating characteristics curve (AUC). A net reclassification improvement was further calculated to compare the developedKorean Osteoporosis Risk-Assessment Model for Men (KORAM-M) with OSTA. Results: In the development dataset, the prevalence of osteoporosis was 8.1%. KORAM-M, consisting of age and body weight, had a sensitivity of 90.8%, a specificity of 42.4%, and an AUC of 0.666 with a cut-off score of -9. In the validation dataset, similar results were shown: sensitivity 87.9%, specificity 39.7%, and AUC 0.638. Additionally, risk categorization with KORAM-M showed improvedreclassification over that of OSTA up to 22.8%. Conclusion: KORAM-M can be simply used as a pre-screening tool to identify candidates for dual energy X-ray absorptiometry tests.
Clinical Utility of Novel Biomarkers in the Prediction of Coronary Heart Disease
김현창 대한심장학회 2012 Korean Circulation Journal Vol.42 No.4
Coronary heart disease (CHD) is a significant cause of morbidity and mortality worldwide. Many risk prediction models have been developed in an effort to assist clinicians in risk assessment and the prevention of CHD. However, it is unclear whether the existing CHD prediction tools can improve clinical performance, and recently, there has been a lot of effort being made to improve the accuracy of the prediction models. A large number of novel biomarkers have been identified to be associated with cardiovascular risk, and studied with the goal of improving the accuracy and clinical utility of CHD risk prediction. Yet, controversy still remains with regard to the utility of novel biomarkers in CHD risk assessment, and in finding the best statistical methods to assess the incremental value of the biomarkers. This article discusses the statistical approaches that can be used to evaluate the predictive values of new biomarkers, and reviews the clinical utility of novel biomarkers in CHD prediction, specifically in the Korean population.