• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.6
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• pp.401-410
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• 2020

In this study, a real-time Tactical UAS position compensation system based on image information developed to compensate for the weakness of location navigation information during GPS signal interference and jamming / spoofing attack is described. The Tactical UAS (KUS-FT) is capable of automatic flight by switching the mode from GPS/INS integrated navigation to DR/AHRS when GPS signal is lost. However, in the case of location navigation, errors accumulate over time due to dead reckoning (DR) using airspeed and azimuth which causes problems such as UAS positioning and data link antenna tracking. To minimize the accumulation of position error, based on the target data of specific region through image sensor, we developed a system that calculates the position using the UAS attitude, EO/IR (Electric Optic/Infra-Red) azimuth and elevation and numerical map data and corrects the calculated position in real-time. In addition, function and performance of the image information based real-time UAS position compensation system has been verified by ground test using GPS simulator and flight test in DR mode.

• Progress in Medical Physics
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• v.20 no.4
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• pp.225-234
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• 2009

Geant4 (GEometry ANd Tracking) provides various packages specialized in modeling electromagnetic interactions. The validation of Geant4 physics models is a significant issue for the applications of Geant4 based simulation in medical physics. The purpose of this study is to evaluate accuracy of Geant4 electromagnetic physics for proton therapy. The validation was performed both the Continuous slowing down approximation (CSDA) range and the stopping power. In each test, the reliability of the electromagnetic models in a selected group of materials was evaluated such as water, bone, adipose tissue and various atomic elements. Results of Geant4 simulation were compared with the National Institute of Standards and Technology (NIST) reference data. As results of comparison about water, bone and adipose tissue, average percent difference of CSDA range were presented 1.0%, 1.4% and 1.4%, respectively. Average percent difference of stopping power were presented 0.7%, 1.0% and 1.3%, respectively. The data were analyzed through the kolmogorov-smirnov Goodness-of-Fit statistical analysis test. All the results from electromagnetic models showed a good agreement with the reference data, where all the corresponding p-values are higher than the confidence level $\alpha=0.05$ set.

• International Journal of Highway Engineering
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• v.7 no.1 s.23
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• pp.11-20
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• 2005

This study examined the correlation between mechanical properties and LMS(Large molecular size) of binders in hot-recycled asphalt mixtures. Hot-recycled asphalt mixtures were manufactured by various mixing methods. Laboratory tests including indirect tensile strength, wheel tracking test and Kim test were performed for each recycled mixture. Gel-permeation chromatography (GPC) analysis was performed for the binders coated on virgin and old (RAP) aggregates separately. For the purpose of binder aging analysis, a round-shaped virgin coarse aggregates (13mm gravel) were introduced in recycled mixtures. This makes possible to distinguish the virgin aggregates from RAP aggregates in recycled mixtures for GPC sampling. Results of GPC showed that there was significant difference in aging level between the binder coated on RAP and that of virgin aggregates in the same recycled mixture. Regression analysis was performed to correlate mechanical properties to LMS ratio. Results showed that most of the mechanical properties had relatively good correlation with LMS. This trend agree with LMS increase up to some degree, but fails for further LMS increase.

• Progress in Medical Physics
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• v.29 no.1
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• pp.8-15
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• 2018

This work reports the acceptance testing and commissioning experience of the Robotic Intensity-Modulated Radiation Therapy (IMRT) M6 system with a newly released $InCise^{TM}2$ Multileaf Collimator (MLC) installed at the Yonsei Cancer Center. Acceptance testing included a mechanical interdigitation test, leaf positional accuracy, leakage check, and End-to-End (E2E) tests. Beam data measurements included tissue-phantom ratios (TPRs), off-center ratios (OCRs), output factors collected at 11 field sizes (the smallest field size was $7.6mm{\times}7.7mm$ and largest field size was $115.0mm{\times}100.1mm$ at 800 mm source-to-axis distance), and open beam profiles. The beam model was verified by checking patient-specific quality assurance (QA) in four fiducial-inserted phantoms, using 10 intracranial and extracranial patient plans. All measurements for acceptance testing satisfied manufacturing specifications. Mean leaf position offsets using the Garden Fence test were found to be $0.01{\pm}0.06mm$ and $0.07{\pm}0.05mm$ for X1 and X2 leaf banks, respectively. Maximum and average leaf leakages were 0.20% and 0.18%, respectively. E2E tests for five tracking modes showed 0.26 mm (6D Skull), 0.3 mm (Fiducial), 0.26 mm (Xsight Spine), 0.62 mm (Xsight Lung), and 0.6 mm (Synchrony). TPRs, OCRs, output factors, and open beams measured under various conditions agreed with composite data provided from the manufacturer to within 2%. Patient-specific QA results were evaluated in two ways. Point dose measurements with an ion chamber were all within the 5% absolute-dose agreement, and relative-dose measurements using an array ion chamber detector all satisfied the 3%/3 mm gamma criterion for more than 90% of the measurement points. The Robotic IMRT M6 system equipped with the $InCise^{TM}2$ MLC was proven to be accurate and reliable.

• The Journal of the Korea Contents Association
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• v.18 no.4
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• pp.416-427
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• 2018

As the loan size of real estate PF is huge, its market ripple effect gets bigger when overdue occurs. Accordingly, the management of the delinquency rate and macroeconomic analysis are required. As the preceding research mainly proceeded with microeconomic analysis through the real estate PF data of individual banks to evaluate importance of list or analyzed core factors for delinquency, it lacked research on comprehensive real estate PF size. In order to overcome the limitations of such data, this research studied real estate PF delinquency rate of the entire market and effect relationship by the size. The research utilized the size of real estate PF loans, money supply, interest rate, consumer price index(CPI), and GDP data. Also, it applied the first model of VECM as linear relationship between at least two or more variables, following the result of co-integration test. As a result of Granger-causality test, the real estate PF loans delinquency rate is influenced by their loan size, and as a result of impulse response analysis, the interest rate is shown to be affecting delinquency rate the most. Interest rate could risesomeday and aggravate the delinquency rate of real estate PF. Also, risk exposure could be serious as the loan size increases.Therefore, the management of real estate PF delinquency rate requires continuous monitoring, tracking and observing issued loans from a macro point of view. The plans to prevent delinquency will be necessary.

• International Journal of Highway Engineering
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• v.3 no.3 s.9
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• pp.119-133
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• 2001

The stiffness of chemcrete modified asphalt mixtures increase rapidly with time in the presence f oxygen and high temperature, Sometimes the asphalt pavements that have chemcrete modified asphalt mixture applied on the surface none show premature cracking because of the excessive increase in the stiffness f the asphalt mixtures. To mitigate this premature cracking, the chemcrete modified mixtures have been used as a base course material. In this study, the performance of the chemcrete modified asphalt binder and mixtures are investigated through a course of various laboratory tests including dynamic shear rheometer and bending beam rheometer tests for binders and uniaxial tensile fatigue, wheel tracking, and moisture damage tests for the mixtures. And also the resilient modulus of the conventional and chemcrete modified mixtures are compared based on the test results conducted on the specimens obtained from various in-situ test sections. It can be concluded from the tests results that the chemcrete modified mixtures show better rutting resistance than conventional mixtures. The chemcrete modified mixtures may have low temperature cracking when it is applied in the cold region. The stiffness of chemcrete modified mixtures is approximately 50 percent higher than that of conventional mixtures more than two years after the chemcrete modified mixture was applied in the base course.

• Journal of the Korean Society of Radiology
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• v.10 no.1
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• pp.7-13
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• 2016

The goal of this study is to investigate corpus callosum and both internal capsule changes with the internet addiction disorder compared to control group using MR diffusion tensor imaging. A total of 22 teenager volunteers who had 10 high-risk group with internet addiction and 12 normal control group were conducted for this study. Imaging was conducted on a 3 T using a EPI sequence. Image evaluation was analysed of the FA, ADC($10^{-3}mm^2/s$), length(mm). We did select ROI for image tracking on corpus callosum of 5 and including 2(internal capsule). The data from these ROIs were compared statistically among the groups using independent t-test, correlation coefficient. There were significant inter-group differences(p<0.05) among FA, ADC($10^{-3}mm^2/s$) and length(mm). And also significantly negative correlations were fond between FA values of corpus callosum and IAD scale(p=0.000). DTI was shown significant changes of FA and ADC, LNF values in IAD compared to control group. Therefore, our results may provided clinical information for brain wite matter functions.

• Journal of the Korean Society for Marine Environment & Energy
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• v.17 no.3
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• pp.247-256
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• 2014

Recently, camera and RADAR are used for more effective and accurate observation of the bird migration. In recent years, many researches on the bird migration using RADAR are undertaking and in active, thus causes the advent of "RADAR ornithology" as a new academic field. Due to the lack of accessibility, economic feasibility and mobility of weather RADAR, airport searching RADAR and tracking RADAR, Nowadays, a marine RADAR is widely used for a bird observation. In this paper, we deals with a study on development of a remote bird observation system using marine FMCW RADAR, which monitors, records and analyzes bird movement by RADAR image processing and target recognition technology. Also, we conduct first test and second test for availability of the developed system, and verify the system to apply in bird observation domain. Consequently, we figured problems out, and correct the problems to improve the system. The developed system can apply in other domains such as environment evaluation. In the future, the system needs to improve accuracy of statistics and to track migration route of bird.

• Journal of The Korean Association For Science Education
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• v.33 no.7
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• pp.1471-1485
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• 2013

The purpose of this study was to develop a HAM (Heuristic Attention Model) by analyzing the difference between eye movements according to the science achievement of elementary school students on discrimination task. Science achievement was graded by the results of the Korea national achievement test conducted in 2012 for a random sampling of classes. As an assessment tool to check discrimination task, two discrimination measure problems from TSPS (Test of Science Process Skill, developed in 1994) which were suitable for an eye tracking system were adopted. The subjects of this study were 20 students from the sixth grade who agreed to participate in the research. SMI was used to collect EMD (eye movement data). Experiment 3.2 and BeGaze 3.2 programs were used to plan experiments and analyze EMD. As a result, eye movements of participants in discrimination tasks varied greatly in counts and duration of fixation, first fixation duration, and dwell time, according to students' science achievement and difficulty of the problems. By the analysis of EMD, strategies of the students' problem-solving could be found. During problem solving, subjects' eye movements were affected by visual attention; bottom-up attention, top-down attention and convert attention, and aflunter attention. In conclusion, HAM was developed, and it is believed to help in the development of a science learning program for underachievers.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.12B
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• pp.1708-1721
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• 2011

Recent outbreak of cattle diseases such as foot-and-mouth disease(FMD) requires constant monitoring of burial sites of mass cull of cattles. However, current monitoring system takes environmental samples from burial sites with period of between one and two weeks, which makes it impossible for non-stop management of hazardous bio-waste. Therefore, in this study, we suggest an improved real-time environmental monitoring system for such bio-hazardous sites based on wireless sensor networks, which makes constant surveillance of the FMD burial sites possible. The system consists mainly several wireless environmental monitoring sensors(i.e dust, Co2, VOC, NH3, H2S, temperature, humidity) nodes and GPS location tracking nodes. Through analysis of the relayed of the environmental monitoring data via gateway, the system makes it possible for constant monitoring and quick response for emergency situation of the burial sites. In order to test the effectiveness of the system, we have installed a set of sensor to gas outlets of the burial sites, then collected and analyzed measured bio-sensing data. We have conducted simulated emergency test runs and was able to detect and monitor the foul smell constantly. With our study, we confirm that the preventive measures and quick response of bio environmental accident are possible with the help of a real-time environmental monitoring system.