• Journal of Korea Multimedia Society
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• v.25 no.2
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• pp.280-286
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• 2022

In order to efficiently collect data, it is essential to locate the facilities and analyze the movement data. The current technology for location collection can collect data using a GPS sensor, but GPS has a strong straightness and low diffraction and reflectance, making it difficult for indoor positioning. In the case of indoor positioning, the location is determined by using wireless network technologies such as Wifi, but there is a problem with low accuracy as the error range reaches 20 to 30 m. In this paper, using BLE 4.2 built in Raspberry Pi, we implement Bluetooth Smart Ready. In detail, a beacon was produced for Advertise, and an experiment was conducted to support the serial port for data transmission/reception. In addition, advertise mode and connection mode were implemented at the same time, and a 3-count gradual algorithm and a quadrangular positioning algorithm were implemented for Bluetooth RSSI error correction. As a result of the experiment, the average error was improved compared to the first correction, and the error rate was also improved compared to before the correction, confirming that the error rate for position measurement was significantly improved.

• Journal of radiological science and technology
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• v.4 no.1
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• pp.45-53
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• 1981

In examinations of the stomach roentgenography, it is imperative to obtain adequate film density throughout all its different regions. Therefore, it is necessary to use more sophiscated exposure techniques. In order to achieve these purpose, the radiologic technologists must be measured abdominal thickness in variations with patient positions. In consideration of these problem, the author was made an experiment on correction method of kVp and mAs by abdominal thickness in roentgenography of the stomach. The results were summarized as follws: 1. When the patient in erect position, abdominal thickness was the most thickened at the level of 3cm inferior to umbilicus without regard to body habitus and it was the most thickened at the level of 3cm superior to umbilicus in prone and supine position. 2. As a result of measuring film density for stomach, the adequate film density was represented from 0.70 to 2.49 in erect position and $0.28{\sim}1.18$ in supine position, $0.5{\sim}2.45$ in prone position. 3. In order to obtain uniform film density in 1.25, the correction factor for kVp by abdominal thickness was represented average ${\pm}4.5kVp\;per\;{\pm}1cm$ in a fixed 50 mAs, and average ${\pm}3.9kVp\;per\;{\pm}1cm$ in a fixed 100mAs. 4. In order to obtain uniform film density in 1.25, the correction factor for mAs by abdominal thickness was represented average ${\pm}30.9%\;per\;{\pm}1cm$ in a fixed 80 kvp and ${\pm}26.9%\;per\;{\pm}1cm$ in a fixed 100kVp.

• Archives of Craniofacial Surgery
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• v.14 no.1
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• pp.36-40
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• 2013

Background: Correction of unilateral blepharoptosis is unexpectedly difficult because healthy eye is often affected by Hering's law. Methods: We measured changes of marginal reflex distance (MRD1) on the unaffected eyelids between preoperative and 3-month postoperative photographs after ptosis correction. This study analyzed 134 unilateral blepharoptosis patients with ptosis correction from February 2002 to February 2011. Fifty patients among them were negative in Hering's law dependence test. From the preoperative and postoperative photographs the MRD1 of unaffected upper eyelids were measured and adjusted with the average pupil diameter of Koreans. Mean age was 34.4 and male was 30 and female was 20. Average follow-up periods were 14 months. Results: Thirteenth unaffected eyes (26%) showed decreased MRD1, and 3 patients (6%) showed decreased MRD1 value over 1.0 mm. Then 3 patients needed additional operations for correction of preoperatively unaffected but ptotic eyelids. Conclusion: There were no meaningful data statistically in the value of MRD1 in every unaffected eye of the patients and in the difference between preoperative and postoperative MRD1 of groups divided according to severity, causes, and types of operation.

• Progress in Medical Physics
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• v.9 no.3
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• pp.163-173
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• 1998

Nuclear medicine emission computed tomography(ECT) can be very useful to diagnose early stage of neuronal diseases and to measure theraputic results objectively, if we can quantitate energy metabolism, blood flow, biochemical processes, or dopamine receptor and transporter using ECT. However, physical factors including attenuation, scatter, partial volume effect, noise, and reconstruction algorithm make it very difficult to quantitate independent of type of SPECT. In this study, we quantitated the effects of attenuation and scatter using brain SPECT and three-dimensional brain phantom with and without applying their correction methods. Dual energy window method was applied for scatter correction. The photopeak energy window and scatter energy window were set to 140ke${\pm}$10% and 119ke${\pm}$6% and 100% of scatter window data were subtracted from the photopeak window prior to reconstruction. The projection data were reconstructed using Butterworth filter with cutoff frequency of 0.95cycles/cm and order of 10. Attenuation correction was done by Chang's method with attenuation coefficients of 0.12/cm and 0.15/cm for the reconstruction data without scatter correction and with scatter correction, respectively. For quantitation, regions of interest (ROIs) were drawn on the three slices selected at the level of the basal ganglia. Without scatter correction, the ratios of ROI average values between basal ganglia and background with attenuation correction and without attenuation correction were 2.2 and 2.1, respectively. However, the ratios between basal ganglia and background were very similar for with and without attenuation correction. With scatter correction, the ratios of ROI average values between basal ganglia and background with attenuation correction and without attenuation correction were 2.69 and 2.64, respectively. These results indicate that the attenuation correction is necessary for the quantitation. When true ratios between basal ganglia and background were 6.58, 4.68, 1.86, the measured ratios with scatter and attenuation correction were 76%, 80%, 82% of their true ratios, respectively. The approximate 20% underestimation could be partially due to the effect of partial volume and reconstruction algorithm which we have not investigated in this study, and partially due to imperfect scatter and attenuation correction methods that we have applied in consideration of clinical applications.

• Progress in Medical Physics
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• v.15 no.3
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• pp.149-155
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• 2004

Purpose: To investigate the effects of tissue inhomogeneity corrections on the dose delivered to prostate cancer patients treated with Intensity-Modulated Radiation Therapy (IMRT). Methods and Materials: For five prostate cancer patients, IMRT treatment plans were generated using 6 MV or 10 MV X-rays. In each plan, seven equally spaced ports of photon beams were directed to the isocenter, neglecting the tissue heterogeneity in the body. The dose at the isocenter, mean dose, maximum dose, minimum dose and volume that received more than 95% of the isocenter dose in the planning target volume ( $V_{p>95%}$) were measured. The maximum doses to the rectum and the bladder, and the volumes that received more than 50, 75 and 90% of the prescribed dose were measured. Treatment plans were then recomputed using tissue inhomogeneity correction maintaining the intensity profiles and monitor units of each port. The prescription point dose and other dosimetric parameters were remeasured. Results: The inhomogeneity correction reduced the prescription point dose by an average 4.9 and 4.0% with 6 and 10 MV X-rays, respectively. The average reductions of the $V_{p>95%}$ were 0.8 and 0.9% with the 6 and 10 MV X-rays, respectively. The mean doses in the PTV were reduced by an average of 4.2 and 3.4% with the 6 and 10 MV X-rays, respectively. The irradiated volume parameters in the rectum and bladder were less decreased; less than 2.1 % (1.2%) of the reduction in the rectum (bladder). The average reductions in the mean dose were 1.0 and 0.5% in the rectum and bladder, respectively. Conclusions: Neglect of tissue inhomogeneity in the IMRT treatment of prostate cancer gives rise to a notable overestimation of the dose delivered to the target, whereas the impact of tissue inhomogeneity correction to the surrounding critical organs is less significant.

• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.508-510
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• 2004

In this paper, we proposed the GPS position data correction method for autonomous land navigation using vanishing point property and a monocular vision system. Simulations are carried out over driving distances of approximately 60 km on the basis of realistic road data. In straight road, the proposed method reduces GPS position error to minimum more than 63% and positioning errors within less than 0.5m are observed. However, the average accuracy of the method is not presented. because it is difficult to estimate it in curve road or other road environments.

• Proceedings of the KIEE Conference
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• 2003.10b
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• pp.187-189
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• 2003

Conventional Switched Mode Power Supplies(SMPS) with diode-capacitor rectifier have distorted input current waveform with high harmonic content. Typically, these SMPS have a power factor lower than 0,65. To improve with this problem the power factor correction(PFC) circuit of power supplies has to be introduced. Specially. to the reduce size and manufacture cost of power conversion device, the single-stage PFC converter is increased to demand as necessary of study. in this paper, The comparative analysis of power factor correction circuit using Feedforward control with average current mode flyback converter(single-stage) and boost converter(two-stage). Also, the validity of designed and manufactured high power factor flyback converter and boost converter is confirmed by simulation and experimental results.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.41 no.6
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• pp.187-193
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• 2004

In this paper, we proposed the GPS position data correction method for autonomous land navigation using vanishing point property and a monocular vision system. Simulations are carried out over driving distances of approximately 60 km on the basis of realistic road data. On a straight road, the proposed method reduces GPS position error by at least 63% within 0.5 m. However, the average accuracy of the method is not presented, because it is difficult to estimate it on other than a straight road in variable conditions.

• Annual Conference on Human and Language Technology
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• 1994.11a
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• pp.132-139
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• 1994

Cognitive Spelling Therapist generates the candidates for correction of one-letter misspelling words, which correspond to over 80 % of the misspelling words. One-letter misspelling can be divided into four categories, and for each categories Cognitive Spelling Therapist copes them with seperate cognitive therapies. Each therapy is based on cognitive causes of misspelling: figural confusion, pronunciation confusion, and keyboard confusion. Cognitive Spelling Therapist generates three candidates for correction in average. After we tested the correctness of candidates with 185 misspelled words randomly sampled from two typist for two months, Cognitive Spell Therapist showed 97.5 % correction for substitution errors, while insertion, deletion, and transposition errors were perfectly corrected.

• Journal of Biomedical Engineering Research
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• v.11 no.1
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• pp.31-38
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• 1990

Image correction of the fluorescein angiogram with the low contrast and geometrically distorted is studied. The procedure is divided into two steps : A template matching step and a geometrical transformation step. Based on the sequential similiarity detection algorithm, more Improved matching results are obtained with edge enhanced image. For the reference points and the corresponding matchimg points, the geometrical transformationss by the use of the average value of the X, Y translational shifts and a pair of these points, respectively are described. Then the corrected images are obtained using bilinear interpolation. It is proven that the usefullness of this study for the image correction of the ocular fundus fluoresceln angiogram with low contrast and geometrically distorted mainly due to the eye movements.