• The Korean Journal of Nuclear Medicine
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• v.5 no.2
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• pp.65-71
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• 1971

A simplified method for the local blood flow determination by means of $^{86}Rb$ was developed in rats and rabbits. $^{86}Rb$ in the form of chloride mixed with physiological saline was intravenously injected. The doses were $10{\mu}Ci$ for rats and $100{\mu}Ci$ for rabbits, which were injected in less than 5 seconds. The rats were sacrificed after 30 seconds, and the rabbits at the intervals of 10, 20, 40 and 60 seconds, by decapitation or rapid intravenous injection of 3 to 5ml of saturated KCI. After bleeding, the organ and tissue samples, e.g. lungs, renal cortex, jejunum and skeletal muscle were quickly removed. The $^{86}Rb$ uptake in 1 gram of the organs and tissues were measured. On the basis of uptake value, administered dose and body weight, the local blood flow was calculated. Following were the results: 1. The uptake values of $^{86}Rb$ in the above organs and tissues of rats were different from other previous reports, in which the large rats were used. It appears, therefore, that the correction on the basis of body weight is necessary. 2. The uptakes of $^{86}Rb$ in the above organs and tissues of rabbits remained rather stationary within 20 to 40 seconds. 3. The local blood flow in the above organs and tissues were calculated from $^{86}Rb$ uptake in per cent dose per 1 gram tissue for 200 gram body weight. The formula could be applied not only to the rabbits but to the rats. 4. The present method could be applied to the comparison of the local blood flow between the various organs and tissues of the control and experimental animals.

• Geophysics and Geophysical Exploration
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• v.5 no.3
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• pp.193-198
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• 2002

In crosswell ray tomography, the resultant velocity structure could be affected by source static, first-arrival-time picking errors, convergence to a local minimum due to an inappropriate initial velocity model and etc. In the paper, I propose an algorithm that automatically correct the souce static among these error-prone factors. The algorithm automatically corrects source static using the picking times' differences along the source direction. The application of the algorithm to real data produces a quite satisfactory result. Tile algorithm seems to be helpful for users to apply the souce static correction consistently and to acquire accurate velocity structure.

• Journal of Power Electronics
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• v.16 no.2
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• pp.610-620
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• 2016

The compound active clamp zero voltage soft switching (CACZVS) three-phase power factor correction (PFC) converter has many advantages, such as high efficiency, high power factor, bi-directional energy flow, and soft switching of all the switches. Triple closed-loop PI controllers are used for the three-phase power factor correction converter. The control objectives of the converter include a fast transient response, high accuracy, and unity power factor. There are six parameters of the controllers that need to be tuned in order to obtain multi-objective optimization. However, six of the parameters are mutually dependent for the objectives. This is beyond the scope of the traditional experience based PI parameters tuning method. In this paper, an improved chaotic particle swarm optimization (CPSO) method has been proposed to optimize the controller parameters. In the proposed method, multi-dimensional chaotic sequences generated by spatiotemporal chaos map are used as initial particles to get a better initial distribution and to avoid local minimums. Pareto optimal solutions are also used to avoid the weight selection difficulty of the multi-objectives. Simulation and experiment results show the effectiveness and superiority of the proposed method.

• Nuclear Engineering and Technology
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• v.54 no.10
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• pp.3962-3973
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• 2022

Several critical heat flux (CHF) correlations including the look-up table in the MARS code have been assessed for the prediction of CHF in a downward-flow narrow rectangular channel. For the assessment, we built an experiment database that covers pressures between 1.01 and 39.0 bar, gap sizes between 1.09 and 6.53 mm, mass fluxes up to 25,772 kg/m²s, and under one-sided and two-sided heating conditions. The results of the assessment showed that the Kaminaga correlation has the best overall prediction compared to others. However, because the correlation uses global variables, such as inlet and outlet subcooling and total heat transfer area, it is difficult to use in a system code. A new CHF correlation is then proposed by replacing the global variables in the Kaminaga correlation with local ones and adding correction factors to consider the effect of gap size, mass flux, and the number of heating walls. Additional correction factor is added to consider the effect of inlet subcooling. It is shown that the new one is better than the Kaminaga correlation and it is easy to implement to any system code.

• Journal of Biomedical Engineering Research
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• v.30 no.6
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• pp.461-468
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• 2009

Magnetic resonance electrical impedance tomography (MREIT) enables us to perform high-resolution conductivity imaging of an electrically conducting object. Injecting low-frequency current through a pair of surface electrodes, we measure an induced magnetic flux density using an MRI scanner and this requires a sophisticated MR phase imaging method. Applying a conductivity image reconstruction algorithm to measured magnetic flux density data subject to multiple injection currents, we can produce multi-slice cross-sectional conductivity images. When there exists a local region of fat, the well-known chemical shift phenomenon produces misalignments of pixels in MR images. This may result in artifacts in magnetic flux density image and consequently in conductivity image. In this paper, we investigate chemical shift artifact correction in MREIT based on the well-known three-point Dixon technique. The major difference is in the fact that we must focus on the phase image in MREIT. Using three Dixon data sets, we explain how to calculate a magnetic flux density image without chemical shift artifact. We test the correction method through imaging experiments of a cheese phantom and postmortem canine head. Experimental results clearly show that the method effectively eliminates artifacts related with the chemical shift phenomenon in a reconstructed conductivity image.

• Archives of Craniofacial Surgery
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• v.20 no.3
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• pp.170-175
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• 2019

Background: Cryptotia is a congenital anomaly in which the upper part of the retroauricular sulcus is absent and buried underneath the temporal skin. Various surgical techniques have been reported for the correction of cryptotia following Kubo's V-Y plasty in 1933. Conventional methods using a local skin flap, skin grafting, tissue expansion, Z-plasty, and any of these combined approaches can result in skin deficiency of the upper auricle. The aim of this study was to develop a new method that improves cosmetic results and has fewer complications. Methods: This study involved four patients in whom five cryptotia deformities were corrected using V-Y plasty and Z-plasty. After elevation of the flap, acellular dermal matrix (ADM; MegaDerm) that was over 5 mm in thickness was applied to the cephalo-auricular angle and positioned to enhance the projection of the ear. Lastly, the flap was transposed to complete the repair. Results: Between January 2014 and February 2018, cryptotia correction with ADM graft was performed in four patients. None of the patients developed a recurrence of cryptotia, and there were no postoperative complications such as wound infection, seroma formation, and dehiscence. In addition, the procedures resulted in a favorable cosmetic appearance. Conclusion: Based on these findings, i.e., no recurrence and a favorable cosmetic result, when using an ADM graft, it is suggested that this technique could be an alternative method of cryptotia correction. It could also lessen donor-site morbidity when compared to autologous cartilage grafting and be more cost-effective than using cartilage from a cadaver.

• Atmosphere
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• v.24 no.3
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• pp.433-444
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• 2014

Although the Radar-AWS Rainrate (RAR) calculation system operated by Korea Meteorological Administration estimated precipitation using 2-dimensional composite components of single polarization radars, this system has several limitations in estimating the precipitation accurately. To to overcome limitations of the RAR system, the Korea Meteorological Administration developed and operated the RMQ (Radar-based Multi-sensor Quantitative Precipitation Estimation) system, the improved version of NMQ (National Mosaic and Multi-sensor Quantitative Precipitation Estimation) system of NSSL (National Severe Storms Laboratory) for the Korean Peninsula. This study introduced the RMQ system domestically for the first time and verified the precipitation estimation performance of the RMQ system. The RMQ system consists of 4 main parts as the process of handling the single radar data, merging 3D reflectivity, QPE, and displaying result images. The first process (handling of the single radar data) has the pre-process of a radar data (transformation of data format and quality control), the production of a vertical profile of reflectivity and the correction of bright-band, and the conduction of hydrid scan reflectivity. The next process (merger of 3D reflectivity) produces the 3D composite reflectivity field after correcting the quality controlled single radar reflectivity. The QPE process classifies the precipitation types using multi-sensor information and estimates quantitative precipitation using several Z-R relationships which are proper for precipitation types. This process also corrects the precipitation using the AWS position with local gauge correction technique. The last process displays the final results transformed into images in the web-site. This study also estimated the accuracy of the RMQ system with five events in 2012 summer season and compared the results of the RAR (Radar-AWS Rainrate) and RMQ systems. The RMQ system ($2.36mm\;hr^{-1}$ in RMSE on average) is superior to the RAR system ($8.33mm\;hr^{-1}$ in RMSE) and improved by 73.25% in RMSE and 25.56% in correlation coefficient on average. The precipitation composite field images produced by the RMQ system are almost identical to the AWS (Automatic Weather Statioin) images. Therefore, the RMQ system has contributed to improve the accuracy of precipitation estimation using weather radars and operation of the RMQ system in the work field in future enables to cope with the extreme weather conditions actively.

• Industry Promotion Research
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• v.8 no.3
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• pp.137-152
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• 2023

As the world progresses towards a global society as time goes by, it is a natural reality that interpreting the fortunes of people born in foreign countries will inevitably increase in the future. If the time of birth is different, a big problem arises in the theory of MyungLiollgy. Therefore, this researcher decides whether to use the local standard time of the country of birth or convert it to the Korean time zone when a foreign-born person writes four weeks, because the position of the sun determines the time and date, so the local standard time It was concluded that it was appropriate to use it, and to support the discussion on the correction of true solar time in Eastern and Western countries, we carefully selected major countries and major cities where the time difference between the currently used national standard time and the true solar time according to the actual longitude line was expected, and the results were presented. was calculated and derived. As a result of the study, it was confirmed that the time difference between the national standard time and the true solar time is much greater than the general idea. On the other hand, through the case of actual foreign-born people, it was possible to find out the great influence of summer time on the composition of the sandbar, in addition to the influence of the exact time difference on the birth date and cutting time. Through the results of this study, it is thought that we have laid the systematic foundation of the myo-logical theory on the correction of true solar time in Eastern and Western countries for the simplicity of the four weeks of foreign-born people, and this will serve as an opportunity to reduce confusion about the method of simplifying the four weeks of foreign-born people. It is assumed that it will be possible.

• Journal of Korean Foot and Ankle Society
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• v.17 no.2
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• pp.93-99
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• 2013

Purpose: Proximal metatarsal chevron osteotomy for hallux valgus is followed by significant amount of postoperative pain. Periarticular multimodal drug local injection can be an option for pain control. This study was attempted to evaluate the efficacy of the morphine as multimodal drug and to confirm the effect of periarticular multimodal drug local injection on controlling early postoperative pain. Materials and Methods: Between March 2012 and June 2012, 22 patients received proximal metatarsal chevron osteotomy for the correction of hallux valgus deformity. 10 patients (Group A) received periarticular injection of the test solution made with morphine, ropivacaine, ephinephrine and ketorolac. 12 patients (Group B) received periarticular injection of the test solution without morphine. The visual analog scale (VAS) was checked at 2, 4, 6, 8 hours, 1 day and 2 days each after surgery. Results: The VAS score at postoperative 2 hours to 1 day between two groups showed no significant difference, but the VAS score at postoperative 2 days was significantly higher in Group A compared to the VAS score of group B. The amount of additional pain control (tramadol HCL) between two groups showed no significant difference for 3 days after surgery. Conclusion: Periarticular multimodal drug local injection was effective in reducing pain after hallux valgus surgery regardless of mixing with morphine.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.48 no.1
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• pp.71-79
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• 2011

The objective of the imaging pipeline is to transform the original scene into a display image that appear similar, Generally, gamma adjustment or histogram-based method is modified to improve the contrast and detail. However, this is insufficient as the intensity and the chromaticity of illumination vary with geometric position. Thus, MSR (Multi-Scale Retinex) has been proposed. the MSR is based on a channel-independent logarithm, and it is dependent on the scale of the Gaussian filter, which varies according to input image. Therefore, after correcting the color, image quality degradations, such as halo, graying-out, and dominated color, may occur. Accordingly, this paper presents a novel color correction method using a modified image formation model in which the image is divided into three components such as global illumination, local illumination, and reflectance. The global illumination is obtained through Gaussian filtering of the original image, and the local illumination is estimated by using JND-based adaptive filter. Thereafter, the reflectance is estimated by dividing the original image by the estimated global and the local illumination to remove the influence of the illumination effects. The output image is obtained based on sRGB color representation. The experiment results show that the proposed method yields better performance of color correction over the conventional methods.