• Journal of the Institute of Convergence Signal Processing
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• v.5 no.1
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• pp.18-24
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• 2004

SPECT technology is used for the reconstructed image in the field of industry noncontact measurement system. One of the distortion problems in reconstructed image quality is a collimator characterictic. The image distortion is caused by a geometrical structure of the collimator. This paper indicated a correction method to remove the image distortion by the structure of the collimator, and compared with the existing correction method. The correction. method removed the image distortion to use deconvolution of projection data with the shift-variant blurring function in the frequency domain. In this pater, I simulated with the collimator angle and distance between the detector and the center of object. and verified with expeimental data. The validity and limitation of correction method is studied for actual industrial applications.

• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.10
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• pp.1087-1094
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• 2014

In general, a speaker generates nonlinear distortions owing to a design principle, manufacturing process, and so on, which decreases and changes a sound quality. So, if the speaker is linearized by compensating these nonlinear distortions, the sound quality and satisfaction can be increased. In this paper, a new adaptive controller was proposed to be applied for compensating nonlinear distortions of a speaker. Through computer simulations as well as the analytical analysis, it could be shown that it is possible for both conventional adaptive controller and proposed adaptive controller, to be applied for linearizing the speaker with nonlinear distortions. Also, the simulations results demonstrated that the proposed adaptive controller may have faster convergence speed and better capability of compensating the nonlinear distortion than the conventional adaptive controller with nearly equal computation complexity.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.6
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• pp.104-110
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• 2018

Operating mode analysis of a liquid propellant rocket engine(LRE) is a crucial tool through the development of an engine. The operating mode analysis of an engine based on a collection of the acceptance tests of components shows discrepancies when compared to the test results. We propose a correction method for performance parameters to develop an engine analysis model for the gas generator cycle of an LRE. In order to simulate engine behavior, the performance parameters for the analysis model are tuned based on the test results of the 75tf engine of KSLV-II.

• Journal of Radiation Protection and Research
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• v.31 no.4
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• pp.165-171
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• 2006

In Korea, a real-time effective dose measurement system is in development. The system uses 32 high-sensitivity MOSFET dosimeters to measure radiation doses at various organ locations in an anthropomorphic physical phantom. The MOSFET dosimeters are, however, mainly made of silicon and shows some degree of energy and angular dependence especially for low energy photons. This study determines the correction factors to correct for these dependences of the MOSFET dosimeters for accurate measurement of radiation doses at organ locations in the phantom. For this, first, the dose correction factors of MOSFET dosimeters were determined for the energy spectrum in the steam generator channel of the Kori Nuclear Power Plant Unit #1 by Monte Carlo simulations. Then, the results were compared with the dose correction factors from 0.652 MeV and 1.25 MeV mono-energetic photons. The difference of the dose correction factors were found very negligible $(\leq1.5%)$, which in general shows that the dose corrections factors determined from 0.662 MeV and 1.25 MeV can be in a steam general channel head of a nuclear power plant. The measured effective dose was generally found to decrease bit $\sim7%$ when we apply the dose correction factors.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1997.10a
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• pp.283-286
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• 1997

일반적으로 직진 경로를 주행하는 이동로봇의 오차 보정을 위해서는 PI 제어기의 계수 보정이 필요하다. 본 논문에서는 직진 경로를 주행하는 이동로봇의 양쪽 바퀴에서 얻어진 엔코더의 값으로 측정하고, 측정되어진 엔코더의 값을 이용하여 방향과 움직임의 오차를 보정해주는 알고리즘을 PI제어기와 유전알고리즘을 사용하여 최적의 파라미터를 구할 수 있는 방법을 제안하였다.

• Economic and Environmental Geology
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• v.51 no.1
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• pp.39-48
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• 2018

We carried out the standoff compensation data from 2007 to 2011 into four different density borehole models to find out the most effectiveness of standoff compensation charts. First, we investigated the irregular collapse characteristics of gamma ray and cut the non-ideal gamma response to improve the effectiveness of the standoff compensation error data. Effectiveness of detector combinations, density of borehole, and spine and ribs techniques from the modified standoff compensation data was analyzed. As the result of comparison, LSD-MSD combination has been suitable for standoff compensation more than LSD-SSD combination and it is possible to do standoff compensation for soil or weathered zone under groundwater level without fatal errors. Even though error scales of density transformed spine and ribs techniques were generally large compared to the conventional standoff compensation, standoff compensation for soil and weathered zone under groundwater level were sufficiently effective.

• Journal of Radiation Protection and Research
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• v.22 no.1
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• pp.29-33
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• 1997

Neutron room scattering corrections that should be made when neutron detectors are calibrated with a $D_2O$ moderated $^{252}Cf$ neutron source in the center of a calibration room are considered. Such room scattering corrections are dependent on specific neutron source type, detector type, calibration distance, and calibration room configuration. Room scattering corrections for the responses of a thermoluminescence dosimeter and two different types of spherical detectors to neutron source in the Radiation Calibration Laboratory(RCL) neutron calibration facility at the Korea Atomic Energy Research Institute(KAERI) were experimentally determined and are presented. The measured room scattering results are then compared with theoretical results calculated by predicting room scattering effects in terms of parameters related to the specific configuration. Agreement between measured and calculated scattering correction is generally about 10% for three kinds of detectors in the calibration facility.

• Korean Journal of Optics and Photonics
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• v.33 no.4
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• pp.146-158
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• 2022

The detector of a focal-plane-array mid-wave infrared (MWIR) camera has different response characteristics for each detector pixel, resulting in nonuniformity between detector pixels. In addition, image nonuniformity occurs due to heat generation inside the camera during operation. To solve this problem, in the process of camera manufacturing it is common to use a gain-and-offset table generated from a blackbody to correct the difference between detector pixels. One method of correcting nonuniformity due to internal heat generation during the operation of the camera generates a new offset value based on input frame images. This paper proposes a technique for dividing an input image into block image patches and generating offset values using only homogeneous patches, to correct the nonuniformity that occurs during camera operation. The proposed technique may not only generate a nonuniformity-correction offset that can prevent motion marks due to camera-gaze movement of the acquired image, but may also improve nonuniformity-correction performance with a small number of input images. Experimental results show that distortion such as flow marks does not occur, and good correction performance can be confirmed even with half the number of input images or fewer, compared to the traditional method.

• Journal of Animal Science and Technology
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• v.44 no.1
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• pp.1-12
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• 2002

The environmental effects were studied to estimate age and lactation stage adjustment coefficients in the primary linear traits of Holstein dairy cattle in Korea. Calving year month, classifier, age-month at classification and lactation stage were the environmental factors which significantly affected the most of linear traits at the level of 0.01. F values of Stature, strength, body depth, thurl with and rear leg side view were relatively higher in the effects of age-month, and dairy form, rear udder height, rear udder width, and udder cleft had relatively higher F values in the effects of lactation stage. Udder depth were affected highly by both age-month and lactation stage. Through the least square means of traits and the interpolation and smoothing obtained by the regression analysis of log and exponential transformed adjustment coefficients, age-month and lactation stage coefficients were estimated, and applied to real data to check the variation in the age-month and lactation stage effects. The estimated mean squares showed that the variation in all the linear traits significantly were decreased for the adjusted factors without the significant changes of variation in calving year month and classifier. That udder depth adjusted for both the age-month and lactation stage resulted in the decreases of variation in the both effects.

• Korean Journal of Remote Sensing
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• v.20 no.2
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• pp.117-124
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• 2004

A spherical earth surface is used for realistic analysis of the geometrical performance characteristics generated by 2-dimensional line-of-sight (LOS) tilt of the satellite imager using the Time Delay and Integration(TDI) technique. A 2-dimensional LOS tilt ever the spherical Earth surface is proposed to compensate geometric performance degradation caused by the satellite altitude decrease below the normal operation altitude. The compensation can be achieved by TDI re-match without degradation of modulation transfer function and with ground sample distance slightly increased. Effective methods of LOS tilt for the compensation are investigated. This study can be useful for mission assurance and flexibility in imager operation.