• Journal of Radiation Protection and Research
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• v.12 no.1
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• pp.1-11
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• 1987

Central axis percentage depth-doses, P(%), were measured at the points from the 2.5cm depth of reference point to 20 cm depth with 2.5 cm interval. Distance from the X-ray target to the water phantom($30{\times}30{\times}30cm^3$) surface was 1 m, and at this point three different beam sizes of $5cm{\phi},\;10cm{\phi},\;and\;15cm{\phi}$ were used. While the X-ray tube voltage varied from 150 to 250 kV, the tube current remained constant at 5 mA. Absorbed dose rate in water, $\dot{D}_w$, was determined using the air kerma calibration factor, $N_k$, which was derived from the exposure calibration factor, $N_x$, of the NE 2571 ion chamber. The reference exposure rate, $\dot{X}_c$, was measured using the Exradin A-2 ion chamber calibrated at ETL, Japan. The half value layers of the X-rays determined to meet ETL calibration qualities. The absorbed dose rates determined at the calibration point were compared to the values obtained from Burlin's general cavity theory, and the percentage depth-dose values determined from $N_k$ showed a good agreement with the values of the published depth dose data(BJR Suppl. 17).

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.294-297
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• 2002

For the quality control procedure of diagnostic x ray units, a method for simultaneous measurement of air kerma, half value layer and tube potential was developed utilizing a computed radiography system for intraoral radiography and film badge case. The response of average pixel values under the windows were calibrated by x rays generated at tube potentials from 40 to 140 kV with filtration from 1.5 to 3.7 mmAl. The calibration curves for half value layer and tube potential were derived as functions of attenuation factors by the 1.4 mmAl filter and the 0.2 mmCu filter. The energy dependency of the open window response was corrected by the calibration factor as a function of the attenuation factor by the 1.4 mmAl filter. The uncertainty of the estimated half value layer, tube potential and air kerma were 0.2 mmAl, 3.6 % and 5 %, respectively. It was thus suggested that this system could be applied to quality control program to detect the variation of working condition of x ray units in clinical use.

• Journal of Digital Convergence
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• v.11 no.12
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• pp.551-556
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• 2013

The Forearm and the lumbar spine bone mineral density bone mineral density values obtained through, T-score and Z-score correlation between numerical and calibration function obtained as a result of any one part to another part of the results is intended to infer. Groups of 66 patients, 11 patients by age 20-70 were composed of patients measured with the forearm and lumbar spine bone mineral density T-score and Z-score of the survey for each of the three factors that correlated to assess the correlation Find the correction factor to obtain the relationship. Bone mineral density of the correlation coefficient R = 0.769 correction factor is Y = 1.541X + 0.133. T-score of correlation coefficient R = 0.768 and the correction factor Y = 0.715X - 0.4 is Z-score of the correlation coefficient R = 0.635 correction factor Y = 0.751X - 0.162. It is regarded that there will be a clinical availability which can analogize the result of a part by using the result of the other part.

• Analytical Science and Technology
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• v.24 no.3
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• pp.200-211
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• 2011

In this study, 13 compounds including four volatile fatty acids (VFA) and nine volatile organic compounds (VOC) were analyzed by cryogenic trapping-thermal desorption technique. In order to evaluate the analytical method for VFA, calibration experiments were performed using five different sorbent materials. When the calibration results are compared between different sorbents, sampling tube filled with Carbopack X showed the highest response factor (RF) for both VFA and VOC. To validate this new analytical method for VFA using cryogenic trapping-thermal desorption technique, this method was compared with alkali absorption method recommended by the odor prevention law of the Korea Ministry of Environment (KMOE). For this purpose, unknown samples were analyzed by two different methods, i.e., cryogenic trapping-thermal desorption (TD) and alkali absorption with solid phase microextraction (SPME). When the results of two different methods were compared, ratios of concentrations determined by the two analytical methods (TD/SPME) was found as 0.46 (valeric acid) ~ 0.71 (isovaleric acid). Therefore, additional study is required to properly establish and find stable analytical conditions for VFA analysis. Furthermore, comparison between two different methods should be made with more reliable calibration approaches.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.8
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• pp.38-48
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• 2014

In this paper, a design of Signal Processing Analog Front-End IC for Automotive Piezo-Resistive Type Pressure Sensor is presented. In modern society, as the car turns to go from mechanical to electronic technology, the accuracy and reliability of electronic parts required importantly. In order to improve these points, Programmable Gain Amplifier (PGA) amplifies the received signal in accordance with gain for increasing the accuracy after PRT Sensor is operated to change physical pressure signals to electrical signals. The signal amplified from PGA is processed by Digital blocks like ADC, CMC and DAC. After going through this process, it is possible to determine the electrical signal to physical pressure signal. As processing analog signal to digital signal, reliability and accuracy in Analog Front-End IC is increased. The current consumption of IC is 5.32mA. The die area of the fabricated IC is $1.94mm{\times}1.94mm$.

• Journal of Radiation Protection and Research
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• v.22 no.4
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• pp.243-250
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• 1997

A relative-calibration-method of solid-state-track-detector for measurement of radon in air has been developed, and the concentration of radon in each room of a 15th-floor-apartment was measured by using the relative calibrated SSTD. There is a tendency to decrease the concentration of radon when the floor is higher, but the main factor to reduce the concentration of radon in room appeared to be ventilation rate. Average concentration of radon of the 15th-floor-apartment was $1.50{\pm}0.51pCi/l$, and the highest and the lowest concentration of radon were $2.68{\pm}0.32pCi/l$, $0.69{\pm}0.16pCi/l$ respectively.

• Journal of the Korean Society for Nondestructive Testing
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• v.21 no.1
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• pp.80-90
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• 2001

The aim of this study is to develop the methodology which enables to identify the mechanical properties of element such as stress intensity factor by using the AE parameters. Considering the multivariate and nonlinear properties of AE parameters such as ringdown count, rise time, energy, event duration and peak amplitude from fatigue cracks of machine element the principal component regression(PCR) and artificial neural network(ANN) models for the estimation of stress intensity factor were developed and validated. The AE parameters were found to be very significant to estimate the stress intensity factor. Since the statistical values including correlation coefficients, standard mr of calibration, standard error of prediction and bias were stable, the PCR and ANN models for stress intensity factor were very robust. The performance of ANN model for unknown data of stress intensity factor was better than that of PCR model.

• Journal of Radiation Protection and Research
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• v.16 no.1
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• pp.15-24
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• 1991

Radon-222 exhalation rate from several domestic building materials were experimentally measured by using radon cup method, in which a CR-39 plastic is used as a passive radon detector. The radon detection factor of CR-39 detector determined in a series of calibration experiments was $0.164{\pm}0.005(tracks\;cm^{-2}/Bq\;d\;m^{-3})$, which is consistent with those reported by other investigators. The radon exhalation rates of several building materials (brick, red brick, concrete block, granite plate, concrete floor and wall) ranges from $6.8{\times}10^{-6}\;(granite plate)\;to\;75.0{\times}10^{-6}Bq/m^2-sec(brick)$ with the increasing order of granite plate, red brick, concrete wall, concrete block, concrete floor and brick. It showed that the CR39 radon cup can be efficiently utilized in measuring the radon-222 gas exhalation rate from building materials.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.57 no.3
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• pp.296-300
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• 2012

Discrimination of geographic origin of agricultural products is a important issue in Korea because the price difference between Korean domestic and imported cereals is a key among some reasons. NIRS (Near Infrared Reflectance Spectroscopy) has been applied to classify the geographical origin of soybeans. Total 135 samples (Korean domestic 92 and foreign 43) were used to obtain calibration equation through 400~2,500 nm wavelength. The math treatment with 1st derivative and 4 nm gap and the modified partial least squares(MPLS)regression was outstanding for calibration equation. The standard error of calibration and determination coefficient in calibration set(n=115) was 6.65 and 0.98, respectively. And it showed that the extra 20 samples for validation equation were identified their authentication correctly. This study describes that the application of NIRS would be possible for discrimination of geographical origin between Korean domestic and imported soybeans.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.3
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• pp.511-518
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• 1997

The technique of fretting fatigue test was developed and fretting fatigue tests of A12024-T4 were conducted under several conditions. The newly developed calibration methods for measuring surface contact tractions showed good linearity and repeatability. The plate type specimen to which tow bridge type pads were attached and vision system was used to observe the crack behaviour. The oblieque cracks appeared in the early stage of crack growth and they became mode I cracks as they grow about 1 mm. The mode I transition points were found to be longer when surface tractions are higher or bulk stress is lower. Before the crack becomes mode I crack, 'well point' where crack grow about rate is minimum, was detected under every experimental condition. The crack behaviour was found to be affected by surface tractions, contact area, bulk stress. It was also found that partial slip and stick condition is most detrimental and the crack starts from the boundary of stick and slip. For gross slip crack started at the outside edge of pad. After crack mode transition, fretting fatigue cracks showed almost same behaviour of plain mode I fatigue cracks. Equivalent stress intensity factor was used to analyze the behaviour of fretting fatigue cracks and it was found that stress intensity factors can be applied to fretting fatigue cracks.