• Title/Summary/Keyword: Inverse square law

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Image Recovery Using Nonlinear Modeling of Industrial Radiography (산업용방사선영상의 비선형모델링에 의한 영상복구)

  • Hwang, Jung-Won;Hwang, Jae-Ho
    • Journal of the Institute of Electronics Engineers of Korea SP
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    • v.45 no.4
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    • pp.71-77
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    • 2008
  • This paper presents a methodology for recovering the industrial radiographic images from the effects of nonlinear distortion. Analytical approach based on the inverse square law and Beer's law is developed in order to improve a mathematic model of nonlinear type. The geometric effect due to dimensions of the radioactive source appeals on the digitized images. The relation that expresses parameters values(angle, position, absorption coefficient, length, width and pixel account) is defined in this model, matching with the sample image. To perform the search for image recovery most similar to the model, a correction procedure is designed. The application of this method on the radiographic images of steel tubes is shown and recovered results are discussed.

Design of a Radiation Spectroscopy Detector using a Spherical Scintillator and Development of a Radiation Source Position Tracking System (구형의 섬광체를 이용한 방사선 스펙트로스코피 검출기 설계 및 방사선원 위치 추적 시스템 개발)

  • Lee, Seung-Jae
    • Journal of the Korean Society of Radiology
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    • v.14 no.6
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    • pp.725-731
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    • 2020
  • A radiation spectroscopy detector using a spherical scintillator was designed, and a system was developed to track the position of a radiation source using several detectors. The position tracking algorithm was designed based on the theory that the number of radiations decreases according to the inverse square law of distance, and the position of the radiation source was calculated by measuring the number of radiations generated from the radiation sources at various positions. The radiation generated from the radiation source is detected by different coefficients in each detector, and the difference between these detected coefficients varies in proportion to the inverse square of the distance. Geant4 Application for Tomographic Emission (GATE) simulation was performed to verify and evaluate the performance of the designed radiation source position tracking system, and radiation generated from radiation sources placed at different positions was counted with each detector. The number of measured radiations was tracked through the radiation source position tracking algorithm, and the error between the actual radiation source position and the position calculated by the algorithm was evaluated. The error between the position of the actual radiation source and the calculated position was measured as an average of 0.11% on the X-axis and 0.37% on the Y-axis, and it was verified that the position can be measured very accurately.

Dose Characteristics by the Co-60 Source Oscillations in High Dose Rate After Loading Irradiations (고선량율 원격강내조사의 코발트-60 이동선원에 의한 선량특성)

  • 최태진;김옥배;노홍균
    • Progress in Medical Physics
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    • v.1 no.1
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    • pp.51-60
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    • 1990
  • Dose distributions around Co- 60 moving source in high dose rate remote afterloading unit, Buchler 3K unit, were experimented with X-omat V films and calculations. In our experiments, film dosimetries have achieved to evaluated the axial dose distributions for source oscillations were 0, 3.5, 5.0 and 6.0 cm in periodically, In results, the dose distributions in axial of source movement showed apparently higher than in transverse direction caused by source locations, dwelling time and air gap in the applicator. In the calculations, the dose rate was derived by using the inverse square law, filteration corrections and Meisberger constant for scatter corrections as source movings. In our experiments and calculations, the average dose uncertainties were showed -2.1$\pm$1.9% in fixed sourdce, -2.9$\pm$1.8%, -7.4$\pm$6.1% and -6.7$\pm$4.6% at 3.5 cm, 5.0 cm and 6.0 cm source oscillations, but the calculations have showed very close to experimental dose rate within 4 cm distance from source.

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The study on the development of noise prediction program for construction sites (건설공사장 소음예측 프로그램 개발에 관한 연구)

  • Yoon, Je-Won;Kim, Young-Chan;Kang, Hee-Man;Kim, Chul-Hwan;Chang, Tae-Sun;Lee, Ki-Jung
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2007.05a
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    • pp.974-977
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    • 2007
  • 본 연구에서는 건설 공사소음 예측 및 가설방음벽 설계를 위해 개발한 공사장 소음예측 프로그램에 대해 소개하고자 한다. 또한, 건설장비가 운영되는 동안 이격거리별 소음측정을 수행한 후 측정결과와 해석결과와의 비교검토를 통해 개발 프로그램의 타당성을 검증하고자 하며, 상용되고 있는 소음해석 전용 소프트웨어를 이용해 다양한 경우에 대한 소음해석을 수행한 후 해석결과를 개발 프로그램의 해석결과와 비교함으로서 개발 프로그램의 타당성을 검증하는 것을 본 연구의 목적으로 한다.

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An optical encryption system for Joint transform correlator (JTC 구조를 이용한 광학적 영상 암호화 시스템)

  • 박세준;서동환;이응대;김종윤;김정우;이하운;김수중
    • Proceedings of the IEEK Conference
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    • 2001.06b
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    • pp.63-66
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    • 2001
  • In this paper a binary image encryption technique and decryption system based on a joint transform correlator (JTC) are Proposed. In this method, a Fourier transform of the encrypted image is used as the encrypted data and a Fourier transform of the random phase is used as the key code. The original binary image can be reconstructed on a square law device, such as a CCD camera after the joint input is inverse Fourier transformed. The proposed encryption technique does not suffer from strong auto-correlation terms appearing in the output plane. Based on computer simulations, the proposed encryption technique and decoding system were demonstrated as adequate for optical security applications.

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An Experimental Study on the Propagation of Impulse Noise in the Far Sound Field (원음장에서의 충격성 소음전파에 관한 실험적 연구)

  • 송화영;제현수;이주원;이성태;이동훈
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2004.05a
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    • pp.852-855
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    • 2004
  • This experimental study describes the propagation characteristics of the impulse noise emitted from the exit of a straight pipe attached to the open end of a simple shock tube. The sound pressure level and directivity of the impulse noise propagating from the exit of pipe with several different diameters are measured in the far sound fold for the range of the incident shock wave Mach number between 1.07 and 1.26. The experimental results showed that the peak values of impulse noises had a strong dependance on the exit diameter of a pipe and the shock wave Mach number. The impulse noise had the directivity propagating toward to the pipe axis and the characteristics of inverse square law of propagation distance. Moreover, it was shown that the one-third octave band SPL of impulse noise was almost constant regardless of the frequency band.

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AN EMPIRICAL RELATION BETWEEN CAlI EMISSION FLUX EXCESS AND STELLAR AGE FOR LATE TYPE MAIN SEQUENCE STARS

  • Park, Young-Deuk;Yun, Hong-Sik
    • Journal of The Korean Astronomical Society
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    • v.16 no.2
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    • pp.31-42
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    • 1983
  • Making use of a relation proposed by Wielen (1977), a new empirical relation between Call emission flux and stellar age is derived by analyzing Wilson and Woolley's spectroscopic data (1970) of late type main sequence stars (K0-M5) and kinematic properties of those stars given by Gliese (1969). The proposed relation shows that the emission flux excess of the Call H-K lines, $F_k'+F_k'$ introduced by Linsky et al. (1979) decreases with stellar age $\tau$ as $\tau^{-0.51}$, consistent with the inverse square law as noted by Skumanich (1972).

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Development of Total Body Irradiation Program (전신방사선조사 프로그램 개발)

  • Choi Byung Ock;Jang Ji Sun;Kang Young Nam;Choi Ihl Bohng;Shin Sung Kyun
    • Progress in Medical Physics
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    • v.16 no.3
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    • pp.130-137
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    • 2005
  • In total body irradiation (T81) for leukemia, we have a two methode. One is a AP (anterior-posterior) method and the other is a Lateral methode. Our hospital used lateral methode. T81 must consider about body contour, because of homogeneous dose distribution. For compensation about irregular body contour, we use compensator. For T81 treatment, we must be considered, accurate manufacture of compensator and accurate calculation of dose. We developed the automatic program for T81. This program accomplished for compensator design and dose calculation for irregular body. This program was developed for uses to use in a windows environment using the IDL language. In this program, it use energy data for each energy: TMR, output factor, inverse square law, spoiler, field size factor. This program reduces the error to happen due to the manual. As a development of program, we could decrease the time of treatment plan and care the patient accurately.

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Dose Distribution of Rectum in the treatment of Uterine Cervical Cancer using Remote Afterloading System (RALS시행시 선원의 거리 이동및 직장선량에 관한 계산치와 측정치의 비교연구)

  • 김성규;신세원;김명세
    • Progress in Medical Physics
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    • v.5 no.1
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    • pp.67-74
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    • 1994
  • Dose distribution of point source represents an inverse square law as the distance, Difference of measurement value and calculation value according to moving distance of radiation source show very large error in dose calculation of Brachytherapy. Therefore, in RALS of high dose rate, dose calculation have an important effect in treatment of uterine cervix cancer and recurrent rate. In this paper, authors measured moving distance of radiation source carrying out RALS. And we measured Rectum dose compared with calculationdose.

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Design and Analysis of Experimental Anechoic Chamber for Localization

  • Kim, Keon-Wook
    • The Journal of the Acoustical Society of Korea
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    • v.31 no.4
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    • pp.225-234
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    • 2012
  • The anechoic chamber is essential tool to measure the various acoustic parameters with high precision. The chamber provides the climate controlled indoor environments but requires the dedicated room at a great cost in order to isolate and absorb sound field. Provided the purpose of the chamber is specific to the experiments of sound localization, the performance requirements excluding free field can be alleviated for cost effective solution. This paper designs low cost and profile anechoic chamber based on acoustic pyramids and evaluates the performance specified by the Annex of ISO 3745. Data analysis is employed to measure the free and hemi-free field performance over five straight paths for working areas and four paths for non-working areas. The identical two measurement campaigns were conducted for free and hemi-free field chamber which is easily interchangeable by simple labor in this chamber design. In the working area with conventional speaker, the results of these analyses demonstrate that lab-designed anechoic chamber is in conformance with ISO 3745 for 250 Hz - 16 kHz one-third octave band at free field chamber and for 1 kHz - 16 kHz one-third octave band at hemi-free field chamber.