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PCA와 Sammon Mapping 분석을 통한 센서 어레이 패턴들의 실시간 가시화 방법
변형기 ( Hyung Gi Byun ),최장식 ( Jang Sik Choi ) 한국센서학회 2014 센서학회지 Vol.23 No.2
Sensor arrays based on chemical sensors produce multidimensional patterns of data that may be used discriminate between different chemicals. For the human observer, visualization of multidimensional data is difficult, since the eye and brain pro-cess visual information in two or three dimensions. To devise a simple means of data inspection from the response of sensor arrays, PCA (Principal Component Analysis) or Sammon`s nonlinear mapping technique can be applied. The PCA, which is a well-known statistical method and widely used in data analysis, has disadvantages including data distortion and the axes for plotting the dimensionally reduced data have no physical meaning in terms of how different one cluster is from another. In this paper, we have investigated two techniques and proposed a combination technique of PCA and nonlinear Sammom mapping for visualization of multidimensional patterns to two dimensions using data sets from odor sensing system. We conclude the combination technique has shown more advantages comparing with the PCA and Sammon nonlinear technique individually.
금속산화물센서의 이산화염소 가스에 대한 감지거동에 관한 연구
유준부 ( Joon-boo Yu ),변형기 ( Hyung-gi Byun ) 한국센서학회 2020 센서학회지 Vol.29 No.3
Chlorine dioxide is very effective gas for sterilization or disinfection (in manufacturing), and does not produce harmful by-products after use. However, if its concentration exceeds 10 %, it become explosive and cannot be compressed or stored. Therefore, it is necessary to measure its concentration. In this study, the concentration of chlorine dioxide with a high oxidizing strength was measured using a metal oxide sensor. The sensor was a commercially available TGS series from Figaro. The sensitivity of the sensor was inversely proportional to a low concentration of chlorine dioxide gas below 6 ppm and returned to the initial resistance at about 6 ppm. When the gas concentration reached multiples of 10 ppm, resistance of the sensor increased to several megaohms.
유전 알고리즘과 러프 집합을 이용한 계층적 식별 규칙을 갖는 가스 식별 시스템의 설계
방영근(Yonug-Keun Bang),변형기(Hyung-Gi Byun),이철희(Chul-Heui Lee) 대한전기학회 2012 전기학회논문지 Vol.61 No.8
Recently, machine olfactory systems as an artificial substitute of the human olfactory system are being studied actively because they can scent dangerous gases and identify the type of gases in contamination areas instead of the human. In this paper, we present an effective design method for the gas identification system. Even though dimensionality reduction is the very important part, in pattern analysis, We handled effectively the dimensionality reduction by grouping the sensors of which the measured patterns are similar each other, where genetic algorithms were used for combination optimization. To identify the gas type, we constructed the hierarchical rule base with two frames by using rough set theory. The first frame is to accept measurement characteristics of each sensor and the other one is to reflect the identification patterns of each group. Thus, the proposed methods was able to accomplish effectively dimensionality reduction as well as accurate gas identification. In simulation, we demonstrated the effectiveness of the proposed methods by identifying five types of gases.
휘발성유기화합물가스에 대한 폴리아닐린 센서의 감도 향상
유준부,유비,임정옥,변형기,허증수,Yu, Joon-Boo,Liu, Fei,Lim, Jeong-Ok,Byun, Hyung-Gi,Huh, Jeung-Soo 한국재료학회 2007 한국재료학회지 Vol.17 No.8
Nano-structured polyaniline have been synthesized by interfacial polymerization method at room temperature. An aqueous solution of aniline in chloroform and another solution of ammonium peroxydisulfate in doping acid were prepared at different times terminated with methanol at room temperature. SEM, UV-vis were used to characterize the polyaniline with regard to their morphology and structure. The diameter and length of polyaniline can be controlled by the reaction time. Nano-structured polyaniline were found to have superior sensitivity for volatile organic compounds(VOCs). As the reaction time to increase from 30minute to 2hours the sensitivity were decreased to VOCs vapors. The sensitivity of Nano-structured polyaniline sensor appeared to VOCs better than the sensitivity of chemical synthesis sensors. The sensitivity of Nano-structured polyaniline sensor improved benzene vapors.
PDA를 이용한 휴대용 Electronic Nose 시스템 개발
김정도 ( Jeong Do Kim ),변형기 ( Hyung Gi Byun ),함유경 ( Yu Kyung Ham ) 한국센서학회 2004 센서학회지 Vol.13 No.6
N/A We have designed a portable electronic nose (e-nose) system using an array of commercial gas sensors and personal digital assistants (PDA) for the recognition and analysis of volatile organic compounds (VOC) in the field. Field screening of pollutants has been a target of instrumental development during the past years. A portable e-nose system was advantageous to localize the special extent of a pollution or to find pollutants source. The employment of PDA improved the user-interface and data transfer by Internet from on-site to remote computer. We adapted the Lavenberg-Marquardt algorithm based on the back-propagation and proposed the method that could predict the concentration levels of VOC gases after classification by separating neural network into two parts.
임베디드 시스템에서 DFS 기법을 이용한 동적 전력 관리
권기현(Ki Hyeon Kwon),김남용(Namyong Kim),변형기(Hyung-Gi Byun) 한국디지털콘텐츠학회 2009 한국디지털콘텐츠학회논문지 Vol.10 No.2
In order to decrease the power consumption in Embedded Linux environment based on XScale PXA255, We produce the device driver of DFS(Dynamic Frequency Scaling) technique, design and implement the middleware DFM(Dynamic Frequency Management) to scale the power of embedded target board with porting this device drive, suggest the method to reduce the Embedded system’s power consumption.