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타원형 광구조물을 갖는 비분산 적외선 알코올 센서의 특성
이승환,김진호,강병도,인정민,Yi, SeungHwan,Kim, JinHo,Kang, ByoungDo,Ihn, JeongMin 한국자동차안전학회 2015 자동차안전학회지 Vol.7 No.2
NDIR (Non-dispersive infrared Rays) alcohol sensor has been prototyped and its temperature characteristics were measured. In order to design novel optical alcohol sensor, elliptical structures with one common foci were modeled and analyzed their optical properties. After analyzing elliptic optical structures, a prototype alcohol sensor module was tested according to the temperature variations from $-20^{\circ}C$ to $35^{\circ}C$. The offset voltages of alcohol sensor decreased from 1.1056 V at the temperature $-20^{\circ}C$ to 0.7339 V at $35^{\circ}C$. However, the highest sensitivity of alcohol sensor showed about $303{\mu}V/ppm$ at room temperature.
혈중 알코올 농도와 호흡기 알코올 농도 상관성: 한국인 남성
이승환,남범우,서정석,Yi, SeungHwan,Nam, BeomWoo,Seo, JeongSeok 한국자동차안전학회 2015 자동차안전학회지 Vol.7 No.4
The relationship between BAC(Blood Alcohol Concentrations) and BrACs(Breath Alcohol Concentrations) and also partition ratio of healthy Korean adult males (96 males) are researched in this paper and its dependency is described according to TBW (total body water), BMI (body mass index), BFM (body fat mass), and PBF (percentage of body fat). Among the above four variables, TBW affects significantly to the partition ratio compared to the other variables. The partition ratio of Korean healthy males showed 1,913 (95 % Confidence Interval (C.I.) from 1,889 to 1,937) for the whole time intervals. However, when Q was averaged after 60 minutes later, its values was 2,011 (95 % C.I. from 1,982 to 2,040). Bland-Altman plots showed the compatibility of measurement methods of multi-gas analyzer, and the biases according to the partition ratios (Q=2,100 and Q=1,913) gave -0.0052 % (95 % CI from -0.0059 to -0.0045%) and -0.0004 % (95 % CI from -0.0011 to +0.0003%), respectively.
이승환(SeungHwan Yi),이곤재(Gon-Jae Lee),한승오(Seungoh Han) 대한전기학회 2009 전기학회논문지 Vol.58 No.3
Piezoresistive pressure sensor have become the successfully-commercialized MEMS product and the related technologies have been well developed over the past decades. Regarding the design methodology, however, the coupled-physics FEM analyses of the transducer itself and the signal-processing circuitry design based on the conventional EDA are separated and both of the analyses were sequentially processed for the full design of the pressure sensor. For the fast and effective R&D, new design methodology is proposed in this paper where the FEM results are linked to the EDA environment and therefore most of the design works can be done in the EDA environments, which means the time-consuming FEM analyses can be minimized. In order to verify the proposed approach, a typical piezoresistive pressure sensor having the silicon diaphragm and piezoresistors was modeled and analyzed based on the proposed methodology. The verification results showed that the simulated results were matched well with the measured data within the 7% difference while the simulation time was reduced less than 5% compared to the conventional methodology. Through the proposed approach, various types of the piezoresistive pressure sensors can be developed in more effective way.
White-Cell 구조를 응용한 비분산 적외선 이산화탄소 센서의 온도특성
이승환 ( Seunghwan Yi ),박영환 ( Younghwan Park ),이재경 ( Jaekyung Lee ) 한국센서학회 2016 센서학회지 Vol.25 No.5
NDIR CO₂ gas sensor was prototyped with ASIC implemented thermopile sensor which included temperature sensor and White-Cell structure in this paper. The temperature dependency of dual infrared sensors (CO₂ and reference IR sensors) has been characterized and their output voltage ratios according to the temperature and gas concentration were presented in this paper for achieving temperature compensation algorithm. The initial output voltages of NDIR CO₂ gas and reference IR sensors showed 3<sup>r</sup><sup>d</sup> order polynomial and linear output voltages according to the variation of ambient temperatures from 253 K to 333 K, respectively. The output voltages of temperature sensor presented a linear dependency according to the ambient temperature and could be described with . The characteristics of output voltage ratios could be modeled with five parameters which are dependent upon the ambient temperatures and gas concentration. The estimated CO₂ concentrations showed relatively high error below 300 ppm (maximum 572 % at 7 ppm CO₂ concentration), however, as the concentration increased from 500 ppm to 2,000 ppm, the overall estimated errors of CO₂ concentrations were less than ±10% in this research.
이승환 ( Seunghwan Yi ) 한국센서학회 2021 센서학회지 Vol.30 No.1
The motivation of this paper is to easily analyze the properties of nondispersive infrared gas sensor that has more than two different optical path length and to suggest the criterion and definition of infrared light absorbance in order to minimize the measurement errors. With the output voltage ratios and the normalized derivatives of infrared ray (IR) absorbance, when the normalized derivatives of IR absorbance decreases from 0.28 to 0.10, the lower and higher limits of errors were decreased from -5.62% and 2.39% to -4.27% and 2.78%. When the normalized derivatives of IR absorbance were 0.10, the output voltage could be partitioned into two regions with one exponential equation and the temperature compensation error was less than 5%.
광학적 가스센서 특성 향상을 위한 광 공동 구조의 고찰
박종선(JongSeon Park),이승환(SeungHwan Yi) 한국가스학회 2008 한국가스학회지 Vol.12 No.4
본 논문은 적외선 센서의 광 강도 및 효율을 증가시키기 위해 새로운 오목한 반사 벽면(curved mirror surface)과 기존의 수직 반사 벽면(vertical mirror surface)구조와의 모의해석 및 실험 결과에 대해 기술하였다. 모의해석 결과 수직 반사 벽면을 사용했을 때 적외선 센서 필터 표면에 도달하는 광의 분포는 타원 형상으로 적외선 센서 표면에 도달함을 볼 수 있고, 오목한 반사 벽면을 사용하는 경우에는 광이 원형 상으로 집광되는 것을 볼 수 있었다. 따라서 초기 평행광의 면적보다 작은 면적으로 집광됨으로 인해 단위면적당 광 강도는 향상되고, 이에 따라 광학적 센서의 출력전압은 향상될 것이라 예측되었다. 이 모의해석을 근간으로 하여 25℃, 45%R.H.에서 이산화탄소를 0 ppm에서 2500 ppm까지 250 ppm 간격으로 주입시켰을 때, 오목한 반사 벽면의 광 공동이 수직 반사 벽면의 광 공동보다 출력전압이 약 200 ㎷ 증가하였다. This paper describes about the simulation and the experimental results of optical cavity with curved mirror surface and vertical mirror surface to improve the light intensity and efficiency of the optical sensors. When we use the vertical mirror surface, the distribution of light reached to the filter surface of detector shows an elliptical shape. Whereas, the curved mirror surface focuses the light into circular shape. Therefore, due to focusing effects in case of using curved mirror surface, the light intensity per unit area has been improved. Consequently, the output voltage of gas sensor has been expected to increase. Based upon the simulation, the experiment of gas sensor has been conducted with CO₂ gas from 0ppm to 2,500 ppm at 250 ppm step and 25℃, 45%R.H. ambient. The output voltage of gas sensor that has a curved mirror surface increases approximately 200 ㎷ than that of vertical mirror surface.