• Title/Summary/Keyword: counting process

Search Result 212, Processing Time 0.028 seconds

High-Resolution Fluorescence Near-Field Imaging of Individual Nanoparticles via the Tip-Induced Quenching Technique

  • Park, Won-Hwa;Kim, Zee-Hwan
    • Bulletin of the Korean Chemical Society
    • /
    • v.28 no.12
    • /
    • pp.2195-2199
    • /
    • 2007
  • We demonstrate that high-resolution (~60 nm) near-field fluorescence images of fluorescent nanospheres can be obtained by utilizing the tip-induced fluorescence quenching process. A time-stamped photon counting (TSPC) technique employed enables us to efficiently measure the degree of fluorescence quenching caused by the dielectric or metallic atomic force microscopy tip. We find that the degree of quenching is not only determined by the tip-material but also by the local morphology of the tip. The fringe patterns around individual nanospheres observed are explained in terms of the interference between the excitation field that is directly induced by the laser source, and the scattered excitation field from the tip.

Classification of the Length of Ceramic Fibers by Settling Process (중력침강에 의한 세라믹 섬유의 길이분류)

  • 김제균;최광훈;오승진;정윤중;강대갑;이재춘
    • Journal of the Korean Ceramic Society
    • /
    • v.31 no.2
    • /
    • pp.161-170
    • /
    • 1994
  • For the preparation of short ceramic fibers of which average length might be in accordance with the opening size of sieve, e.g., 150${\mu}{\textrm}{m}$ or 300${\mu}{\textrm}{m}$, bulk fibers were grounded on sieve screen by applying both compressing and shearing force, and passed through the sieve screen. The grounded fibers were subjected to gravitational settling processes. The classified fibers were observed by scanning electron microscopy and the length of each fiber was measured to correlate the average length with the opening size of the sieve used for grinding bulk fibers. Theoretical analysis show that a free settling technique is ineffective for the classification of fibers by length compared with that of particles. The average lengths of classified fibers estimated by scanning electron microscopy were in good agreement with those obtained by relative packing volume of the fibers. Accordingly, it is confirmed that average fiber lengths can be determined from bulk volume data without photographing, counting and averaging results for hundreds of fibers.

  • PDF

Filter Calibration using Self Oscillation of Biquad RC Filter (바이쿼드 RC 필터의 자가 발진을 이용한 필터 교정)

  • Ahn, Deok-Ki;Hwang, In-Chul
    • The Transactions of The Korean Institute of Electrical Engineers
    • /
    • v.59 no.5
    • /
    • pp.1005-1009
    • /
    • 2010
  • This paper presents a digitally-controlled filter calibration technique for biquad RC filter using self oscillation. The biquad RC filter is converted to a fully-differential ring oscillator by changing its resistor connections, where the oscillation frequency reflects the cut-off frequency. The proposed calibration circuit measures the oscillation frequency by counting with a fixed higher-frequency clock and then tunes it to a desired frequency with a digital frequency-locked loop including a PI controller. Because the proposed circuit directly measures the cut-off frequency of the filter itself and calibrates it with the small area digital circuits, the area and the power consumption are much small compared with conventional works. When it is implemented in a 65nm CMOS process, the calibration circuit except the filter consumes the area of 80um X 50um and power consumption is 443uA at 1.2 V supply voltage.

Effects of Informative Censoring in the Proportional Hazards Model (비례위험모형에서 정보적 중도절단의 효과)

  • 정대현;홍승만;원동유
    • Journal of Applied Reliability
    • /
    • v.2 no.2
    • /
    • pp.121-133
    • /
    • 2002
  • This paper concerns informative censoring and some of the difficulties it creates in analysis of survival data. For analyzing censored data, misclassification of informative censoring into random censoring is often unavoidable. It is worthwhile to investigate the impact of neglecting informative censoring on the estimation of the parameters of the proportional hazards model. The proposed model includes a primary failure which can be censored informatively or randomly and a followup failure which may be censored randomly. Simulation shows that the loss is about 30% with regard to the confidence interval if we neglect the informative censoring.

  • PDF

An Analysis of 2D Positional Accuracy of Human Bodies Detection Using the Movement of Mono-UWB Radar

  • Kiasari, Mohammad Ahangar;Na, Seung You;Kim, Jin Young
    • Journal of Sensor Science and Technology
    • /
    • v.23 no.3
    • /
    • pp.149-157
    • /
    • 2014
  • This paper considers the ability of counting and positioning multi-targets by using a mobile UWB radar device. After a background subtraction process, distinguishing between clutters and human body signals, the position of targets will be computed using weighted Gaussian mixture methods. While computer vision offers many advantages, it has limited performance in poor visibility conditions (e.g., at night, haze, fog or smoke). UWB radar can provide a complementary technology for detecting and tracking humans, particularly in poor visibility or through-wall conditions. As we know, for 2D measurement, one method is the use of at least two receiver antennas. Another method is the use of one mobile radar receiver. This paper tried to investigate the position detection of the stationary human body using the movement of one UWB radar module.

Kernel Estimation of Hazard Ratio Based on Censored Data

  • Choi, Myong-Hui;Lee, In-Suk;Song, Jae-Kee
    • Journal of the Korean Data and Information Science Society
    • /
    • v.12 no.2
    • /
    • pp.125-143
    • /
    • 2001
  • We, in this paper, propose a kernel estimator of hazard ratio with censored survival data. The uniform consistency and asymptotic normality of the proposed estimator are proved by using counting process approach. In order to assess the performance of the proposed estimator, we compare the kernel estimator with Cox estimator and the generalized rank estimators of hazard ratio in terms of MSE by Monte Carlo simulation. Two examples are illustrated for our results.

  • PDF

Absolute Measurement of the Quantum Efficiency of Photodetectors Using Correlated Photon Pairs (광자쌍을 이용한 광검출기의 양자효율 절대측정)

  • 안경진
    • Korean Journal of Optics and Photonics
    • /
    • v.4 no.4
    • /
    • pp.452-456
    • /
    • 1993
  • The quantum efficiencies of photomultiplier tubes were measured by counting the coincidence photon pairs generated in the process of spontaneous parametric down-conversion. They were measured within 3% accuracy over the range of wavelength from 560 to 850 nm without any standard light source or detector. The values for 633 nm correspond to those obtained with a calibrated laser power meter within the measurement error.

  • PDF

A Design of Single Pixel Readout Circuit for Digital X-ray Image Sensor (디지털 X-ray 이미지 센서용 Single Pixel Readout 회로 설계)

  • Kang, Hyung-Geun;Jeon, Sung-Chae;Jin, Seoung-Oh;Lim, Gyu-Ho;Woo, Eum-Chan;Huh, Young;Sung, Kwan-Young;Park, Mu-Hun;Ha, Pan-Bong;Kim, Young-Hee
    • Proceedings of the IEEK Conference
    • /
    • 2006.06a
    • /
    • pp.563-564
    • /
    • 2006
  • A single photon counting type image sensor which is applicable for medical diagnosis with digitally obtained image and industrial purpose has been designed using $0.25{\mu}m$triple well CMOS process.

  • PDF

Counting the number of cars waiting at the traffic light by computer vision process (컴퓨터비전 처리에 의한 교통신호 차례를 기다리는 차량 댓수의 계수)

  • 조준희;김희승
    • Proceedings of the Korean Information Science Society Conference
    • /
    • 2003.10b
    • /
    • pp.562-564
    • /
    • 2003
  • 지능형 교통 시스템(intelligent traffic system)의 필요성은 컴퓨터비전기술의 발전에 따라 성장해오고 있다. 지능형 교통 시스템의 바람직한 방법들 중 하나는 비전처리를 통하여 자동차의 수를 계수하는 것이다. 차량이 포함된 도로 이미지들은 디지털 카메라에 의하여 촬영된다. 우선적으로 이미지에서 도로의 중앙선 오른쪽부분은 제외한다. 단순히 개개의 차량을 분리해 나는 것은 겹치는 문제, 그림자, 조명과 같은 많은 문제점을 가지고 있다. 차량계수를 목적으로 이미지를 세밀히 조사하다가 보니 낮에는 차량의 앞 범퍼 끝의 그림자로 밤에는 헤드라이트 불빛으로 차량을 식별할 수 있다는 것을 알 수 있었다. 이 논문에서는 그림자분석을 통한 차량계수를 다루었다. 이 특징을 사용하여 차량을 계수하여 만족할만한 정확성을 성취하는 것이 이 논문의 목표이다.

  • PDF

A Study on Filtration System Model and Comparative Performance Tests of Automotive (여과시스템 모델과 자동차 연료필터의 비교성능시험 연구)

  • 이재천
    • Journal of the Korean Society for Precision Engineering
    • /
    • v.20 no.3
    • /
    • pp.194-201
    • /
    • 2003
  • This study presents the comparative filtration performance evaluation of automotive fuel filters based on the theory of Beta ratio. For the experiments, the fuel component's test stand incorporating the multi-pass filtration test circuit was developed. A mathematical description of filtration process in general was derived. And the theoretical basis of multi-pass test and the test procedure were described in detail. Experimental results revealed that domestic fuel filter tested could not maintain consistent Beta ratio, that is filtration efficiency, although it had the holding capacity of contaminants close to the specification at maximum pressure drop across the filter assembly. The results of experiments and simulations also showed that filtration system model could be refined including desorption ratio to estimate the variable Beta ratio in service life.