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NMOS 소자에 대한 Ru<sub>1</sub>Zr<sub>1</sub> 합금 게이트 전극의 특성
이충근,강영섭,홍신남,Lee, Chung-Keun,Kang, Young-Sub,Hong, Shin-Nam 한국전기전자재료학회 2004 전기전자재료학회논문지 Vol.17 No.6
This paper describes the characteristics of Ru-Zr alloy gate electrodes deposited by co-sputtering. The various atomic composition was made possible by controlling sputtering power of Ru and Zr. Thermal stability was examined through 600 and 700 $^{\circ}C$ RTA annealing. Variation of oxide thickness and X-ray diffraction(XRD) pattern after annealing were employed to determine the reaction at interface. Low and relatively stable sheet resistances were observed for Ru-Zr alloy after annealing. Electrical properties of alloy film were measured from MOS capacitor and specific atomic composition of Zr and Ru was found to yield compatible work function for nMOS. Ru-Zr alloy was stable up to $700^{\circ}C$ while maintaining appropriate work function and oxide thickness.
이충근,신항식,공인덕,이명호,Lee, Chung-Keun,Shin, Hang-Sik,Kong, In-Deok,Lee, Myoun-Ho 대한의용생체공학회 2011 의공학회지 Vol.32 No.2
Assuming that photons absorbed by a vessel do not have acute variations, DC component reflect the basal blood volume (or diameter) before blood pulsation. Vascular stiffness and reflection is influenced by changes in basal blood volume (or diameter). This paper describes analysis of the characteristic variations of vascular stiffness, according to relative variations in DC components of the PPG signal (25-75%). For quantitative analysis, we have used parameters that were proposed previously, reflection and stiffness index, and the second derivative of PPG waveform, b/a and d/a. Significantly, the vascular stiffness and reflections were increased according to increase in DC component of the PPG signal for more than about 3% of baseline values. The systolic blood pressure were increased from $113.1{\times}13.18$ to $116.2{\times}13.319$ mmHg, about 2.76% (r = 0.991, P < 0.001) and the AC component of the PPG signal were decreased from $2.073{\times}2.287$ to $1.973{\times}2.2038$ arbitrary unit, about 5.09% (r = -0.993, P < 0.001). It is separated by DC median and correlation analysis was performed for analyzing vascular characteristics according to instantaneous DC variations. There are significant differences between two correlation coefficients in separated data.
독립요소분석을 이용한 태아심전도 추출을 위한 시변 칼만 평활기의 개발
이충근(Chung Keun Lee),김봉수(Bong Soo Kim),권자영(Ja Young Kwon),최영득(Young Deuk Choi),송광섭(Kwang Soup Song),남기창(Ki Chang Nam) 대한전자공학회 2012 전자공학회논문지 Vol.49 No.10
태아심박의 모니터링은 태아의 안녕을 평가하기 위해 중요한 정보이다. 비관혈적인 태아심전도는 산모의 복부 신호로부터 추출될 수 있다. 따라서 산모 복부의 혼합 신호로부터 태아심전도를 추출하기 위해 많은 유망한 신호처리 방법들이 개발되어 왔다. 그러나 비관혈적인 태아심전도는 안정적인 신호 측정법이 부족하고 신호처리 방법의 어려움으로 여전히 임상에서 널리 적용되지 못하고 있다. 태아심전도를 추출하는 신호처리 결과는 가우시안 백색잡음에 의해 신호대잡음비가 낮아질 수 있다. 본 논문에서는 태아심전도에서 시간에 따라 변하는 백색잡음 신호를 제거하여 신호대잡음비를 높이기 위한 방법으로 시변 칼만 평활기를 제안하였고 그 가능성을 확인하였다. Wiener 과정을 시스템 모델로 설정하고 백색잡음 크기에 따라 공분산 행렬을 수정하였으며, 이를 통해 칼만 이득을 변화시켜 평활화 정도를 가변시킬 수 있도록 설계하였다. 5채널 태아심전도 모델을 이용하여 백색잡음의 크기에 따른 최적 공분산 행렬 값을 구하였고, 모의실험을 통해 제안된 방법의 가능성을 확인할 수 있었다. Fetal heart rate monitoring is important information to assess fetal well-being. Non-invasive fetal ECG (electrocardiography) can be derived from maternal abdominal signal. And various promising signal processing methods have been introduced to extract fetal ECG from mother’s composite abdominal signal. However, non-invasive fetal ECG monitoring still has not been widely used in clinical practice due to insufficient reliable measurement and difficulty of signal processing. In application of signal processing method to extract fetal ECG, it might be lower signal to noise ratio due to time varying white Gaussian noise. In this paper, time varying Kalman smoother is proposed to remove white noise in fetal ECG and its feasibility is confirmed. Wiener process was set as Kalman system model and covariance matrix was modified according to white Gaussian noise level. Modified error covariance matrix changed Kalman gain and degree of smoothness. Optimal covariance matrix according to various amplitude in Gaussian white noise was extracted by 5 channel fetal ECG model, and feasibility of proposed method could be confirmed.
수정된 라플라시안 센서를 이용한 심박변이도 측정에 관한 연구
이충근(Chung-Keun Lee),신항식(Hang-Sik Shin),김홍래(Hong-Rae Kim),이정환(Jeong-Whan Lee),김용준(Yong-Jun Kim),이명호(Myoung-Ho Lee) 대한전기학회 2009 전기학회논문지 Vol.58 No.5
Heart Rate Variability(HRV) is a parameter that represents monitoring variability of time intervals between R-peak in electrocardiography. HRV serves to various applications, such as indices of autonomic functions, prediction of cardiac sudden death, assessment of stress and emotional, etc. However, as measuring R-peak in ECG needs at least 3-electrodes, and it is inconvenient for end users. In this paper, we suggested the modified laplacian electrodes for measuring HRV at one-point, which are producted by MEMS fabrication and have the two circular electrodes on the pad. For optimal position and direction, we performed an experiment that compared with pearson correlation coefficient and the amplitude of signals, between standard lead II and proposed electrodes. We analyzed the HRV parameters, such as standard deviation of the NN interval(SDNN), high frequency(HF), low frequency(LF), LF/HF ratio. The result showed that the average correlation coefficient and amplitude are 0.967 and 0.685 mVpp at the position 2. The coeffiecient correlation between the standard HRV and proposed electrode-HRV is 0.999.
Business Analytics를 이용한 기업 지식관리시스템 구축 사례 연구
이충근 ( Chung Keun Lee ),이수용 ( Soo Yong Lee ),이군희 ( Gun Hee Lee ) 한국지식경영학회 2013 지식경영연구 Vol.14 No.4
Although business Intelligence system is introduced to many companies over the past decade, The result of business benefits from BI investment are not so significant than expected. But still successful BI system can provide the ability to analyse business information in order to support and improve management decision making across a broad range of business activities. In recently, Business Analytics System(BA) is emerging as advanced alternative of outdated and inefficient BI System. This study is focus on constructing procedure of BA system in KB card company, which is major credit card company in South Korea. In practice there were just few works that mentioned well-designed environment of KMS system, and other contribution of this study is to make a platform which invoke revelation of collective intelligence in data analytic professional users group.
이충근(Chung Keun Lee),이동현(Dong Hyun Lee),박희찬(Hee Chan Park),유태일(Tae Il Yoo),유상열(Sang Yeol Yoo),정병석(Byung Sok Jung) 대한설비공학회 2010 대한설비공학회 학술발표대회논문집 Vol.2010 No.6
In order to compare the concentrations of the indoor air qualities according to living conditions, this thesis measured and compared the concentrations of the fine dusts before and after vacuuming, the formaldehydes of living rooms and bedrooms, and the dust mites on beds and on cotton sofas from 1st of July to 14th of September in 2009 for the total 179 households including 110 general households, 23 multi-children households and 46 low income households in Seoul and Kyung ki areas. Among them, it was 8 cases(4.5%) that the formaldehyde baseline about livingroom were exceeded, and was 26 cases(14.5%) that one about bedroom were exceeded. All of three groups presented the higher formaldehyde concentrations in bedrooms than one in living rooms. The excessive level of the formaldehyde baseline in bedroom according to the features of living conditions were higher in general households than in multi-children and low income households, and they statistically had a slight similarity(p<0.001). The excessive concentration of formaldehyde was higher in bedrooms than in living rooms, and the reasons were that the bedrooms were smaller than living rooms, the various furniture were arranged in the bedrooms’ small spaces, and the times to ventilate bedrooms were less by comparison with living rooms.