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[Co / Cu / NiFe / Cu] 다층박막의 자기저항효과에 관한 연구
정진봉(J. B. Jeong),박창만(C. M. Park),이기암(K. A. Lee),황도근(D. G. Hwang),이상석(S. S. Lee) 한국자기학회 1995 韓國磁氣學會誌 Vol.5 No.3
A study of the dependence of the magnetoresistance in glass\[Cu_(xÅ)\NiFe_(50Å)\Cu_(xÅ)\Co_(50Å)]_N (X = 8, 10, 14, 18, 22, 26, 28, 38, 48, 58 Å, N = 2, 3, 4, 10, 20) multilayers prepared by dc magnetron sputtering on the interlayer thickness of Cu (X), the number of multylayer(N) and annealing temperature has been performed. Resistance measurement were made by four terminal method, and the magnetic field applied to perpendicular and parallel for the current. The maximum magnetoresistance(MR) ratio(%) was appeared in the vicinity of 10 Å in Cu layer, and it was oscillated with the thickness of Cu. The MR ratio was increased with the number of layers N, however the ratio for the N = 4 layers decreased rather than the N = 3 layers. The dependence of the ratio on the annealing temperature was increased to 250 ℃.
강정아(Jeong A Kang),이유선(Yeu Seon Lee),정승현(Seung Hyeon Jeong),이정우(Jeong Woo Lee),김보영(Bo Yeong Kim),임대승(Dea Seung Im),이민수(Min Soo Lee),김정희(Jeong Hee Kim),정준용(Jun Young Jeong),최시완(Si Wan Choi),정진옥(Jin Ok J 대한내과학회 2002 대한내과학회지 Vol.63 No.2
Background: Coronary artery spasm plays an important role in the pathogenesis of variant angina. However the precise mechanism (s) and the clinical characteristics of variant angina remain to be elucidated. We investigated the clinical characteristics and diagnostic features of variant angina. Methods: The clinical characteristics and coronary angiographic findings were analyzed in 178 patients with angiographically documented coronary artery spasm, which developed spontaneously or was provoked by the admistration of intravenous ergonovine maleate. All patients were followed for at least 1 year or more or until their death. Results: One hundred and eleven patients complained of chest pain which developed especially at night and in the early morning. One hundred and thirty three patients (74.7%) were smokers. The electrocardiographic findings at the time of admission showed no changes in 147 cases (82.6%), testes showed ST segment elevation in 22 cases (12.4%), ST segment depression in 2 cases (1.1%), T wave inversion in 7cases (3.9%). The treadmill test was performed in 135 cases, ST segment elevation was noted in 6 patients (4.4%) and ST segment depression in 18 patients (13.3%). All of the other results were within normal range. The ergonovine provovative tests for coronary spasms were safe and effective. The right coronary artery was the most prevalent site of coronary artery spasm. Drug treatment was applied initially to all patients, but only 115 patients (64.5%) received the follow-up. Of these three died from cardiac arrest. The rate of cardiac death was low (1.7%) in patient, which made it difficult to know the risk factors for the cardiac deaths. Two (1.1%) had cardiac arrest. They didn't take any medication. Patients with variant angina usually responded well to nitrates and calcium antagonists. Thus nitrates and calcium antagonists are useful in preventing attacks and abolished attacks of variant angina. Conclusion: In this study, 13.2% of coronary artery disease was variant angina. The effectiveness of drug therapy and the prognosis of the patients was quite good in the group. But when chest pain happens, the adequate use of nitrate agents is needed because of cardia arrest or cardiac death in 2.8% of the patients. (Korean J Med 63:195-202, 2002)
홍종선,김강천,정진아,Hong, C.S.,Kim, G.C.,Jeong, J.A. 한국통계학회 2012 Communications for statistical applications and me Vol.19 No.2
신용평가모형에서 부도로 잘못 예측된 정상 차주의 비율과 정확하게 평가된 부도차주의 비율인 일변량 누적분포함수로 표현된 ROC 곡선을 이용하여 분류성과를 평가한다. 본 연구에서는 스코어 확률변수를 이변량으로 확장하여 부도와 정상 차주의 결합누적분포함수를 이용하여 표현할 수 있는 ROC 곡선을 제안한다. 이변량 평균벡터를 통과하는 확률변수의 선형 관계를 이용하여 이변량 ROC 곡선을 구현한다. 그리고 다양한 이변량 정규분포에 대한 ROC 곡선으로부터 분류성과를 탐색하고, 이에 대응하는 AUROC 통계량과 비교분석한다. 본 연구에서 제안한 이변량 ROC 곡선으로부터 분류기준에 적합한 최적분류점을 구하고 이를 통해 이변량 혼합분포함수의 최적 분류기준을 설정할 수 있음을 보인다. For credit assessment models, the ROC curves evaluate the classification performance using two univariate cumulative distribution functions of the false positive rate and true positive rate. In this paper, it is extended to two bivariate normal distribution functions of default and non-default borrowers; in addition, the bivariate ROC curves are proposed to represent the joint cumulative distribution functions by making use of the linear function that passes though the mean vectors of two score random variables. We explore the classification performance based on these ROC curves obtained from various bivariate normal distributions, and analyze with the corresponding AUROC. The optimal threshold could be derived from the bivariate ROC curve using many well known classification criteria and it is possible to establish an optimal cut-off criteria of bivariate mixture distribution functions.