• Journal of Ocean Engineering and Technology
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• v.18 no.4 s.59
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• pp.33-39
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• 2004

This paper presents a hybrid underwater navigation system for unmanned underwater vehicles, using an additional range sonar, where the navigation system is based on inertial and Doppler velocity sensors. Conventional underwater navigation systems are generally based on an inertial measurement unit (IMU) and a Doppler velocity log (DVL), accompanying a magnetic compass and a depth sensor. Although the conventional navigation systems update the bias errors of inertial sensors and the scale effects of DVL, the estimated position slowly drifts as time passes. This paper proposes a measurement model that uses the range sonar to improve the performance of the IMU-DVL navigation system, for extended operation of underwater vehicles. The proposed navigation model includes the bias errors of IMU, the scale effects of VL, and the bias error of the range sonar. An extended Kalman filter was adopted to propagate the error covariance, to update the measurement errors, and to correct the state equation, when the external measurements are available. To illustrate the effectiveness of the hybrid navigation system, simulations were conducted with the 6-d.o.f. equations of motion of an AUV in lawn-mowing survey mode.

• Journal of Conservation Science
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• v.25 no.1
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• pp.61-76
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• 2009

Gwangjueupseong (Gwangju Town Wall) has been found in the site of the Asian Culture Complex (former Provincial Government of Jeonnam) by archaeological field survey. The length of the remaining wall is 85.1m, and the Town Wall consists of ten kinds of rock type. The major rock types are dacite (41.1%) and andesite (35.7%). Dacite composes main rock blocks of the wall, and andesite is used to fill the cavity between main rock blocks. These rocks look very similar to basement rocks of the Mudeung Mountain on the basis of occurrence features, magnetic susceptibility, petrological, mineralogical and geochemical properties. Also, quarrying traces were found on the southwestern slope of the mountain along the Jeungsimsa Temple valley. Thus, it is probable that the rock materials of the Gwangju Town Wall were supplied from the Mudeung Mountain and that they were transported along the Gwangju river.

• Korean Journal of Remote Sensing
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• v.4 no.1
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• pp.31-40
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• 1988

Low-cost microcomputer systems can be assembled which possess computing power, color display, memory, and storage capacity approximately equal to graphic workstactions. A low-cost, flexible, and user-friendly IBM/PC/XT/AT based image processing system has been developed and named as KMIPS(KAIST (Korea Advanced Institute of Science & Technology) Map and Image Processing Station). It can be easily utilized by the resource managers who are not computer specialists. This system can: * directly access Landsat MSS and TM, SPOT, NOAA AVHRR, MOS-1 satellite imagery and other imagery from different sources via magnetic tape drive connected with IBM/PC; * extract image up to 1024 line by 1024 column and display it up to 480 line by 672 column with 512 colors simultaneously available; * digitize photographs using a frame grabber subsystem(512 by 512 picture elements); * perform a variety of image analyses, GIS and terrain analyses, and display functions; and * generate map and hard copies to the various scales. All raster data input to the microcomputer system is geographically referenced to the topographic map series in any rater cell size selected by the user. This map oriented, georeferenced approach of this system enables user to create a very accurately registered(.+-.1 picture element), multivariable, multitemporal data sets which can be subsequently subsequently subjected to various analyses and display functions.

• Journal of radiological science and technology
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• v.46 no.1
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• pp.53-61
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• 2023

The aim of this study analyzed the important level (IL) and understanding level (UL) including the Borich's need for students preparing of the national examination for radiological technologists at online open chatting room. A total of 254 survey were collected from a total of 1,016 students who used open chatting room from December 13 to December 16, 2022. A general characteristics were the age, gender, curriculum (3 or 4 years), grade and area. The IL, UL, learning satisfaction (LS), learning achievement (LA) and intention to continue using (ICU) were analyzed by using the 5 point Likert scale. There was no significant difference the LS, LA, and ICU according to general characteristics (p>0.05). There was a statistically significant difference a total of sixteen subjects based on the t-test results of the response values from the IL and UL (p<0.05). The total of ten subjects with the highest priority in the Locus for Focus models were the Ultrasonography, Human anatomy, Magnetic resonance imaging, Radiation therapy, Cardiovascular and intervention, Computed tomography, Human physiology, Radiographic imaging, Fluroscopic radiography, and Nuclear medicine) that the Borich's need was also the same as the top 10 ranked subjects. The LS (4.23±0.72), LA (4.18±0.73), and ICU (4.15±0.78) for open chatting room were high. This study identified the subjects most needed by college students by the Borich's need analysis. First, it is necessary to provide intensive education on subjects with high scores that are most needed by college students. Second, it is necessary to improve the teaching method for subjects with low need and low level of understanding.

• Journal of the Korean Society of Radiology
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• v.17 no.3
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• pp.401-410
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• 2023

A radiographer is a job in charge of diagnostic imaging equipment, and must contribute to the promotion of public health by suggesting an appropriate level of work. To this end, we intend to present an appropriate level of work through evaluation of human harm according to work, statistical evaluation through questionnaires, and domestic and international trends. In the case of human harm evaluation, considering radiation exposure, 42.6%, shield work, 69.7%, and in the case of magnetic resonance imaging, the maximum length of stay in the examination room should be adjusted to 15 minutes and not exceed 30 times. According to the survey statistics, it was confirmed that the physical and mental burden increased due to the high workload and difficulty compared to working hours. Based on domestic and international trends, it is necessary to adjust the examination standards for domestic radiographers to 36.8% to promote national health through qualitative improvement of radiological examinations. something to do.

• Health Policy and Management
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• v.33 no.3
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• pp.325-337
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• 2023

Background: While there are many studies estimating the effects of private health insurance on various types of health care utilization, few have examined how such effects change in conjunction with important policy reforms in national health insurance (NHI). This study examined how the effect of private health insurance (supplemental and fixed cash benefit) on high-cost outpatient imaging test utilization changed following the expansion of magnetic resonance imaging (MRI) coverage in 2018, which is a key example of the NHI benefit expansion policy in recent years. Methods: Data from the 2017 and 2019 Korea Health Panel Survey, which contained information about healthcare utilization before and after the expansion of MRI coverage in 2018, were used. The incremental effect of private health insurance on high-cost outpatient imaging test utilization for each period were quantified and compared, with special attention given to the type of private health insurance. Results: While people with supplemental private health insurance were more likely to use high-cost outpatient imaging tests than those without, both before and after the expansion of MRI coverage, the incremental effect increased from 1.6% points in 2017 to 2.5% points in 2019. Conclusion: Benefit expansion in NHI does not necessarily reduce disparities in the use of health care between private health insurance subscribers and non-subscribers. The results of our study also suggest that the path through which private health insurance affects healthcare utilization may not be limited to the price mechanism alone but can be more complex.

• Korean Journal of Heritage: History & Science
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• v.38
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• pp.387-419
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• 2005

Material characteristics and provenance interpretation of the raw materials for the stone moulds of bronze artifacts excavated in Galdong Prehistoric site were studied. The stone moulds are made of igneous hornblendite with coarse-grained holocrystalline textures. The surface color shows greenish grey to dark green with greasy luster. The value of magnetic susceptibility of the moulds ranges from 19.2 to 71.0 (mean ; $39.2{\times}10^{-3}$ SI unit).High value of magnetic susceptibility indicates high contents of magnetite as a ferromagnetic mineral and the wide range of the values are due to heterogeneous distribution of magnetite. These are characteristics of basic igneous rocks. The rock-forming minerals of the moulds mainly consist of amphibole, plagioclase and biotite. Pyroxene, chlorite and opaque minerals are also rarely present. A large quantity of carbon was detected on the dark black crust near the surface of the moulds by quantitative analysis. Geological field survey was carried out to identify a source of the raw materials of the stone moulds around Galdong site. Hornblendite or gabbroic rocks being similar to the moulds forming rock occur at Daeseongri, Sikcheonri and Gyodongri in Jangsoo, and Illdaeri in Namwon about 50 kilometers away from the site in a straight line. They have similarity with the moulds forming rock in magnetic susceptibility ranging from 16.1 to 72.4 (mean ; $39.9{\times}10^{-3}$ SI unit). Among those hornblendite or gabbroic rocks, one in Jangsoo area is the most similar to the moulds forming rock on the basis of petrological and mineralogical characteristics. Comparing normalized patterns of major, minor, rare earth and immobile elements contents of the moulds to them of hornblendite in Jangsoo area, geochemical evolution trend and behavior characteristics show affinities between them. It suggests that the moulds forming rock and hornblendite in Jangsoo area have been originated from cogenetic magma. This hornblendite is easy to engrave an inscription or detail graphics on the surface because of its softness, and has good thermal conductivity. Hornblendite in Sikcheonri, Jangsoo is particularly produced and used for stone wares until the present day. Therefore, it is probable that the stone materials of the moulds has been imported from Daeseongri, Sikcheonri and Gyodongri in Jangsoo area. However, it cannot be completely excluded the possibility that the material of the moulds was supplied from Illdaeri in Namwon area appearing the same type of hornblendite on a small outcrops. It is necessary to carry out further archaeological studies to identify several possibilities of migration process of raw materials.

• Journal of Environmental Health Sciences
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• v.37 no.2
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• pp.102-112
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• 2011

Objectives: The purpose of this study is to analyze the effects of chronic exposure by welders to manganese (Mn) through an analysis of the degree of brain activity in different activities such as cognition and motor activities using the neuroimaging technique of functional magnetic resonance imaging (fMRI). The neurotoxic effect that Mn has on the brain was examined as well as changes in the neuro-network in motor areas, and the usefulness of fMRI was evaluated as a tool to determine changes in brain function from occupational exposure to Mn. Methods: A survey was carried out from July 2010 to October 2010 targeting by means of a questionnaire 160 workers from the shipbuilding and other manufacturing industries. Among them, 14 welders with more than ten years of job-related exposure to Mn were recruited on a voluntary basis as an exposure group, and 13 workers from other manufacturing industries with corresponding gender and age were recruited as a control group. A questionnaire survey, a blood test, and an fMRI test were carried out with the study group as target. Results: Of 27 fMRI targets, blood Mn concentration of the exposure group was significantly higher than that of the control group (p<0.001), and Pallidal Index (PI) of the welder group was also significantly higher than that of the control group (p<0.001). As a result of the survey, the score of the exposure group in self-awareness of abnormal nerve symptoms and abnormal musculoskeletal symptoms was higher than those of the control group, and there was a significant difference between the two groups (p<0.05, respectively). In the correlation between PI and the results of blood tests, the correlation coefficient with blood Mn concentration was 0.893, revealing a significant amount of correlation (p<0.001). As for brain activity area within the control group, the right and the left areas of the superior frontal cortex showed significant activity, and the right area of superior parietal cortex, the left area of occipital cortex and cerebellum showed significant activity. Unlike the control group, the exposure group showed significant activity selectively on the right area of premotor cortex, at the center of supplementary motor area, and on the left side of superior temporal cortex. In the comparison of brain activity areas between the two groups, the exposure group showed a significantly higher activation state than did the control group in such areas as the right and the left superior parietal cortex, superior temporal cortex, and cerebellum including superior frontal cortex and the right area of premotor cortex. However, in nowhere did the control group show a more activated area than did the exposure group. Conclusions: Chronic exposure to Mn increased brain activity during implementation of hand motor tasks. In an identical task, activation increased in the premotor cortex, superior temporal cortex, and supplementary motor area. It was also discovered that brain activity increase in the frontal area and occipital area was more pronounced in the exposure group than in the control group. This result suggests that chronic exposure to Mn in the work environment affects brain activation neuro-networks.

• Geophysics and Geophysical Exploration
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• v.8 no.3
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• pp.224-231
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• 2005

In geophysical field surveys, commercial equipments often fail to resolve the subsurface target or even sometimes fail to be applied because they do not fit to the various field situations or the physical properties of the medium or target. We developed a geophysical measurement system, which can be easily adapted for the various field situations and targets. The system based on PXI with A/D converter and some stand alone equipment such as Network Analyzer was applied to borehole radar survey, borehole sonic measurement and electromagnetic noise measurement. The system for borehole radar survey consists of PXI, Network Analyzer, dipole antennas, GPIB interface is used for PXI to control Network Analyzer. The system for borehole sonic measurement consists of PXI, 24 Bit A/D converter, high voltage pulse generator, transmitting and receiving piezoelectric sensors. The electromagnetic noise measurement system consists of PXI, 24 Bit A/D converter, 2 horizontal component electric field sensors and 2 horizontal and 1 vertical component magnetic filed sensors. The borehole radar system has been successfully applied to detect the width of the artificial tunnel through which the borehole pass and to image buried steel pipe, while the commercial borehole radar equipment failed. The borehole sonic system was tested to detect the width of artificial tunnel and showed a reasonable result. The characteristic of electromagnetic noise was grasped at an urban area with the data from the electromagnetic noise measurement system. The system is also applied to characterize the signal distortion by induction between the electric cables in resistivity survey. The system can be applied various geophysical problems with a simple modification of the system and sensors.

• Journal of the Korean earth science society
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• v.39 no.3
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• pp.250-259
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• 2018

We investigated the petrological features of the stone materials used in the Jeolla Usuyeong rampart and estimated their provenance through the geological survey. The Jeolla Usuyeong was designated as a historic site (No. 535) on 2016. Since the remaining rampart is less than 15%, it is necessary to make conservation on it. In this study, we discriminated the stone materials used for the rampart according to their petrographic characteristics and estimated the volume proportion of each stone by the rock type. Also, we measured the whole-rock magnetic susceptibility. The petrographic features of the stones in the rampart were compared with those in the vicinity by their mineral composition and texture. The stone materials of the rampart mainly consist of the tuff, lapilli tuff, and lapilli stone. Among these three kinds of rocks, lapilli tuff is quantitatively the most abundant (60.3%), the next is tuff (34.7%), and lapilli stone (2.5%) shows the least amount. The whole-rock magnetic susceptibility of the tuffaceous rocks can be divided by the value of $1.0{\times}10^{-3}$ SI unit. Also, the compressive strength of tuff exhibits about 156 MPa, which is adequate to reuse for the repairing work. Petrological comparisons between stone materials and outcrop rocks distributed around the Hwawon peninsula leads to a conclusion that the stone materials of the rampart are likely to have been delivered from the Dongoeri and Sindeok-ri. Judging from the results of the comparison on the frequency of use and physical properties among the tuffaceous rocks, tuff is considered to suitable for restoring the rampart.