• Korean Journal of Remote Sensing
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• v.40 no.3
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• pp.257-268
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• 2024

Drone-mounted hyperspectral sensors (DHSs) have revolutionized remote sensing in agriculture by offering a cost-effective and flexible platform for high-resolution spectral data acquisition. Their ability to capture data at low altitudes minimizes atmospheric interference, enhancing their utility in agricultural monitoring and management. This study focused on addressing the challenges of radiometric and geometric distortions in preprocessing drone-acquired hyperspectral data. Radiometric correction, using the empirical line method (ELM) and spectral reference panels, effectively removed sensor noise and variations in solar irradiance, resulting in accurate surface reflectance values. Notably, the ELM correction improved reflectance for measured reference panels by 5-55%, resulting in a more uniform spectral profile across wavelengths, further validated by high correlations (0.97-0.99), despite minor deviations observed at specific wavelengths for some reflectors. Geometric correction, utilizing a rubber sheet transformation with ground control points, successfully rectified distortions caused by sensor orientation and flight path variations, ensuring accurate spatial representation within the image. The effectiveness of geometric correction was assessed using root mean square error(RMSE) analysis, revealing minimal errors in both east-west(0.00 to 0.081 m) and north-south directions(0.00 to 0.076 m).The overall position RMSE of 0.031 meters across 100 points demonstrates high geometric accuracy, exceeding industry standards. Additionally, image mosaicking was performed to create a comprehensive representation of the study area. These results demonstrate the effectiveness of the applied preprocessing techniques and highlight the potential of DHSs for precise crop health monitoring and management in smart agriculture. However, further research is needed to address challenges related to data dimensionality, sensor calibration, and reference data availability, as well as exploring alternative correction methods and evaluating their performance in diverse environmental conditions to enhance the robustness and applicability of hyperspectral data processing in agriculture.

• Journal of IKEEE
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• v.28 no.1
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• pp.38-45
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• 2024

Most previous works about magnetic effect on plasma emission were interested in emission enhancement which was useful to various fields of plasma application. On the contrary, the following work is interested in plasma dissipation rarely reported in prior researches and expected to help advance plasma-controlling technique. Nd:YAG laser (1064 nm, 6 ns) was focused on three kinds of metals (Al, Ti and STS) and air. The permanent magnetic field (0.4 T) of Nd₂Fe₁₄B magnet was provided passing throughout laser-induced plasma. The spectra of plasma in both the presence and absence of the magnetic field were observed with varying laser power and delay time of the spectrograph. In this work it was uniquely discovered that the plasma always dissipated easily in the presence of magnetic field irrespective of the laser power. With the O I(777.42 nm)-line shape function fitted to Lorentz profile, its half width at half maximum (HWHM) was evaluated to verify that the magnetic field increased the plasma density. It is concluded that magnetic field facilitates not only plasma emission enhancement but also plasma dissipation, increasing recombination rate which is proportional to plasma density.

• Journal of Surface Science and Engineering
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• v.57 no.4
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• pp.296-305
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• 2024

The aim of this in vitro study was to evaluate the changes in the roughness and weight of titanium discs treated with 3 different types of magnetostrictive ultrasonic scaler tip. Eighty identical disks (10 mm in diameter), 50 for surface roughness and 30 for weight change, were investigated in this study. For this study, 3 types of scaler tip were used as follows; Powerline(FSI-PWR-1000), Slimline(FSI-SLI-1000), and Thinsert(-16 00037374). The power was set to high power(HP), medium power(MP), and low power(LP), in the blue zone recommended by the manufacturer. Surface topography analysis was carried out using scanning electron microscopy (SEM). Surface roughness measurements, the average surface roughness (Ra) and mean roughness profile depth (Rz), were compared between treated and non-treated surfaces with a profilometer. A PowerLINE-MP of magnetostrictive ultrasonic scalers for implant patients might be recommended when considering changes in the roughness and weight of titanium discs.

• The Korean Journal of Nuclear Medicine Technology
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• v.16 no.1
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• pp.70-75
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• 2012

Purpose: It is important to acquire accurate data because the SPECT scan affected by various physical factors. The aim of this study was to compare the uniformity when both centers were matched or mismatched differed from position of heart in COR. Materials and methods: The images were acquired with cylindrical uniform phantom (6.7 cm diameter, 9 cm length) and heart insert phantom using Cardio MD SPECT system (Philips, USA). The phantoms were positioned on COR as well as four different points which were 10 cm above, below, left and right side from the COR. The counts from the both edge of cylindrical uniform phantom and those from the both wall of heart insert phantom were compared by using vertical and horizontal line profile. In addition, the qualitative evaluation was performed with heart insert phantom images and volunteer test. Results: In heart insert phantom study, the differences of counts between COR and 10 cm above, below, left and right point of COR were 1.1, 4.1, 4.9, 2.2 and 0.9% using T-A curve for horizontal view. In case of vertical view of COR 3.9, 21.9, 3.5, 23.9, 14.0% were shown. In cylindrical phantom study, the differences of counts between COR and 10 cm above, below, left and right point of COR were 4.3, 0.3, 3.3, 2.6 and 0.7% using T-A curve for horizontal view. In case of vertical view of COR 2.7, 3.0, 1.0, 0.3, 3.4% were shown. For qualitative evaluation, the images at COR were the most uniform for both of heart insert phantom and volunteer test, whereas other four positions showed somewhat distorted images. Conclusion: It showed the most uniform images when COR is matched with the heart. Therefore, we can expect that distortion which increased or decreased of myocardial perfusion will be prevented by matching the heart and COR when positioning. Furthermore, the accuracy of diagnosis will be improved as well.

• Journal of Korean Society of Transportation
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• v.21 no.1
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• pp.127-136
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• 2003

Road safety is defined under the minimum design standard and design examination process is consisted of the standard according to current road design. However, road safety in practical way is correlative to not only all element of roads but also road shape, such as, between straight line and curved line and between curved lines. Also. it is related to alignments such as horizontal alignment and vertical alignment, and cross section. That is, the practical road design should be examined in both sides of 3 dimension and consecutiveness (consistency) as the actual road is a 3 - dimensional successive object. The paper presents a concept for acceleration to evaluate consistency of road considering actual road shape on 3-dimension. Acceleration of vehicle is influential to road consistency based on running state of vehicles and state of drivers. The magnitude of acceleration. especially, is a quite influential element to drivers. Based on above, the acceleration on each point on 3-D road can be calculated and then displacement can be done. Computation of acceleration means total calculation on each axis. Speed profile refers to “Development of a safety evaluation model for highway horizontal alignment based on running speed(Jeong, Jun-Hwa, 2001)” and then acceleration can be calculated by using the speed pronto. According to literature review, definition of acceleration on 3-D and g-g-g diagram are established. For example, as a result of the evaluation, if the acceleration is out of range, the road is out of consistency. The paper shows calculation for change of acceleration on imaginary road under minimum design standard and the change tried to be applied to consistency. However accurate acceleration is not shown because the speed forecasting model is limited and the paper did not consider state of vehicles (suspension, tires and model of vehicles). If speed pronto is defined exactly, acceleration is calculated on all road shapes, such as. compound curve and clothoid curve. and then it is appled to consistency evaluation. Unfortunately, speed forecasting model on 3 -D road and on compound curves have rarely presented. Speed forecasting model and speed profile model need to be established and standard of consistency evaluation need to developed and verified by experimental vehicles.

• Progress in Medical Physics
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• v.7 no.1
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• pp.65-77
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• 1996

Using the 2-D and 3-D Hoffman brain phantom, 3-D Jaszczak phantom and Single Photon Emission Computed Tomography, the effects of data acquisition parameter, attenuation, noise, scatter and reconstruction algorithm on image quantitation as well as image quality were studied. For the data acquisition parameters, the images were acquired by changing the increment angle of rotation and the radius. The less increment angle of rotation resulted in superior image quality. Smaller radius from the center of rotation gave better image quality, since the resolution degraded as increasing the distance from detector to object increased. Using the flood data in Jaszczak phantom, the optimal attenuation coefficients were derived as 0.12cm$\^$-1/ for all collimators. Consequently, the all images were corrected for attenuation using the derived attenuation coefficients. It showed concave line profile without attenuation correction and flat line profile with attenuation correction in flood data obtained with jaszczak phantom. And the attenuation correction improved both image qulity and image quantitation. To study the effects of noise, the images were acquired for 1min, 2min, 5min, 10min, and 20min. The 20min image showed much better noise characteristics than 1min image indicating that increasing the counting time reduces the noise characteristics which follow the Poisson distribution. The images were also acquired using dual-energy windows, one for main photopeak and another one for scatter peak. The images were then compared with and without scatter correction. Scatter correction improved image quality so that the cold sphere and bar pattern in Jaszczak phantom were clearly visualized. Scatter correction was also applied to 3-D Hoffman brain phantom and resulted in better image quality. In conclusion, the SPECT images were significantly affected by the factors of data acquisition parameter, attenuation, noise, scatter, and reconstruction algorithm and these factors must be optimized or corrected to obtain the useful SPECT data in clinical applications.

• Journal of Animal Science and Technology
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• v.49 no.4
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• pp.481-490
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• 2007

An experiment was conducted to investigate the effects of dietary supplementation of MOS, lectin and organic acid mixture(Organic acid F, Organic acid G) on the egg production, egg quality, profile of leukocytes and erythrocytes, small intestinal microflora and immune response in laying hens. A total of 900 Hy-line BrownⓇ laying hens of 48 wks old were assigned to one of the following 6 dietary treatments:control(C), C+AvillamycinⓇ 6ppm, C+MOS 250ppm, C+lectin 12.5ppm, C+Organic acid F(formic acid 35.4%, formate 34.6%, potassium 30.0%) 0.3% and C+0rgarnic acid G(fumaric acid 23%, calcium formate 14%, potassium sorbate 5%, calcium propionate 7%) 0.06%. Each treatment was replicated five times with thirty birds per replicate, housed in 2 bird cages. Feeding trial lasted for 6 wks under 16 hours lighting regimen. All supplemental groups were higher than the control in 6 wks hen-day and hen-housed egg production showing the highest with MOS treatment(P<0.05). Soft & broken egg productions were lower in supplemental groups than in the control except lectin treatment(P<0.05). Eggyolk color of supplemental groups was higher than that of the control except Organic acid G treatment(P<0.05). The values of RBC, HB, MCHC were highest in lectin treatment and lowest in MOS treatment(P<0.05). The numbers of intestinal microflora were not significantly different among the treatments. Serum IgG levels of all supplemental groups were higher than those of the control(P<0.05). In conclusion, for supplementation of antibiotics, immune modulators and organic acid mixture improved production parameters in general. Among the supplements, MOS showed the best performance in egg production and eggyolk color.

• 한국해양학회지
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• v.23 no.1
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• pp.24-40
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• 1988

In the Korea Ocean Nodule Development (KONOD)-1 area between the Clarion and Clipperton fracture zones of the northeastern equatorial Pacific, the pelagic sediment layer can be divided into two or three units on air-gun seismic profile. The acoustic units can be also correlated with those in the DSDP site 163 core. The topmost unit (unit I) is acoustically transparent and consists of zeolitic clay and radiolarian ooze of late Oligocene to middle Eocene age. Unit IIA is well-stratified and transparent in the lower part. consisting of the radiolarian ooze intercalated with chert beds and zeolitic clay of early Eocene to Paleocene age. Unit IIB is stratified with layers of silicified and compacted flinty-cherty nannofossil chalk (late Cretaceous) on top of the acoustic basement. Units I and IIA form the Line Islands Formation that overlies an unnamed formation of unit lIB. The entire layers and the unit I layer propressively thin northward, except near the Line Islands Ridge. The distribution of sediment layer has been controlled by the equatorial Cenozoic CCD and the northward spreading of the Pacific plate. The change of CCD corresponding to the subsidence and migration of the plate has determined the sediment composition of the DSDP 163 core passed across the equator of high sedimentation suite. The late Cretaceous sedimentary layer (unit IIB) in the 163 core was formed above the CCD south of the equator. The unit IIA resulted from rapid subsidence of the Pacific plate below the CCD in the Paleocene. The unit IIA is seen only in the west of 149 W. Both the units IIA and I were probably formed during the Pacific plate passing and after leaving the equatorial region respectively since early Eocene. In the south of the KONOD-l area, the unit I was redistributed by bottom current, a branch of the Antarctic Bottom Water flowing eastward guided by the Clipperton fracture zone. The activities of bottom currents were prolonged for a long geological time. Turbidite layers occur more than 350 km from the Hawaiian Ridge to near the Clarion fracture zone. They originated directly from the Hawaiian Ridge, filling the topographic lows.

• The korean journal of orthodontics
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• v.18 no.2
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• pp.459-474
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• 1988

A study was made of a method of rational assessment on the roentgeno-cephalogram in orthodontic practice. Fifty eight measurements were analyzed on the roentgeno-cephalograms of 50 male and 50 female Korean adults with the acceptable profile and the normal occlusion. The means and standard deviations of measurements were studied in male and female groups by various analytic methods, and the sex difference was examined statistically. The obtained data were compared with those of the Japanese and American standards by useing a Japanese adults standard polygon chart reported by lizuka and Ishikawa. Amongs of 58 measurements, 14 have been selected as statistically significant and clinically useful, and used to make a Korean adult standard polygon chart. The results obtained were as follows: 1. Standards for cphalometric analysis in Korean adults were obtained, and the polygon chart and cephalometric profilogram were also made by using the standards in order to apply to a clinical diagnosis. 2. The sex difference was recognized in linear measurements, but not in angular measurments. 3. In comparison with the American standards from Downs and Graber, the Korean showed significant differences in angle of convexity, mandibular plane angle, Y-axis angle, interincisal angle and lower incisor to mandibular plane angle. Thus, the Korean showed a more retruded chin position, convex facial type, than white people. 4. In comparison with the Japanese standards from Iizuka and Ishikawa, the Korean showed a significant similarity with the Japanese, especially in females. 5. Upper incisor to Huxely line angle, established as a new measurement, proved to be paralell to X-Y axis angle.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.31 no.6
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• pp.434-449
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• 2019

In this study, we develop a new cross-shore sediment module which takes the effect of infra-gravity waves of bound mode, and boundary layer streaming on the sediment transport into account besides the well-known asymmetry and under-tow. In doing so, the effect of individual random waves occurring during the unit observation period of 1 hr on sediment transport is also fully taken into account. To demonstrate how the individual random waves would affect the sediment transport, we numerically simulate the non-linear shoaling process of random wavers over the beach of uniform slope. Numerical results show that with the consistent frequency Boussinesq Eq. the application of which is lately extended to surf zone, we could simulate the saw-tooth profile observed without exception over the surf zone, infra-gravity waves of bound mode, and boundary-layer streaming accurately enough. It is also shown that when yearly highest random waves are modeled by the equivalent nonlinear uniform waves, the maximum cross-shore transport rate well exceeds the one where the randomness is fully taken into account as much as three times. Besides, in order to optimize the free parameter K involved in the long-shore sediment module, we carry out the numerical simulation to trace the yearly shoreline change of Mang-Bang beach from 2017.4.26 to 2018.4.20 as well, and proceeds to optimize the K by comparing the traced shoreline change with the measured one. Numerical results show that the optimized K for Mang-Bang beach would be 0.17. With K = 0.17, via yearly grand circulation process comprising severe erosion by consecutively occurring yearly highest waves at the end of October, and gradual recovery over the winter and spring by swell, the advance of shore-line at the northern and southern ends of Mang-Bang beach by 18 m, and the retreat of shore-line by 2.4 m at the middle of Mang-Bang beach can be successfully duplicated in the numerical simulation.