• The Journal of the Convergence on Culture Technology
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• v.10 no.2
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• pp.531-536
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• 2024

Control drones, which are recently classified as smart agricultural machines in the agricultural field, are striving to build smart control and automatic control systems by combining hardware and software in order to shorten working hours and increase the effectiveness of control in the aging era of rural areas. In this paper, the characteristics of the nozzle dedicated to the control drone were analyzed as a basic study for the establishment of management control and automatic control systems. In order to consider various variables such as the type of various drone models, controller, wind, flight speed, flight altitude, weather conditions, and UAV pesticide types, related studies are needed to be able to present the drug spraying criteria in consideration of the characteristics and versatility of the nozzle. Therefore, to enable the consideration of various variables, flow analysis (CFD) simulation was conducted based on the self-designed nozzle, and the theoretical and experimental values of the droplet distribution were compared and analyzed through water reduction experiments. In the future, we intend to calculate accurate scattering in consideration of various variables according to drone operation and use it in management control and automatic control systems.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.38 no.6
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• pp.617-629
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• 2001

The mathematical models for the receptive field of simple cells in the human visual system have been developed in the areas of psychophysics, physiology and neuroscience. The various models used in the fields of digital image processing and computer vision include Gator complex, Gaussian derivatives and Hermite functions. In this paper, the effective widths for the models are derived based on the space-frequency uncertainty principle. The center frequency and parameters related to the models are determined in accordance with the human visual filters, and resultant bandwidths are analyzed. Furthermore, the characteristics of space and frequency for the models is analyzed and compared to the experimental data obtained from psychophysics.

• Journal of Radiation Protection and Research
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• v.30 no.4
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• pp.185-196
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• 2005

Although medical exposure from diagnostic radiology procedures such as conventional x-rays, CT and PET scans is necessary for healthcare purposes, understanding its characteristics and size of the resulting radiation dose to patients is much of worth because medical radiation constitutes the largest artificial source of exposure and the medical exposure is in a trend of fast increasing particularly in the developed society. Annual collective doses and per-caput effective doses from different radiology procedures in Korea were estimated by combining the effective dose estimates per single medical procedure and the health insurance statistics in 2002. Values of the effective dose per single procedure were compiled from different sources including NRPB reports, ICRP 80, MIRDOSE3.1 code and independent computations of the authors. The annual collective dose reaches 27440 man-Sv (diagnostic radiology: 22880 man-Sv, nuclear medicine: 4560 man-Sv) which is reduced to the annual per-caput effective dose of 0.58 mSv by dividing by the national population of 47.7 millions. The collective dose is far larger than that of occupational exposures, in the country operated 16 nuclear power plants in 2002, which is no more than 70 man-Sv in the same year. It is particularly noted that the collective dose due to CT scans amounts 9960 man-Sv. These results implies that the national policy for radiation protection should pay much more attention to optimization of patient doses in medicine.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.11
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• pp.1128-1134
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• 2014

In this paper, the effects of a metamaterial slab with negative permeability in a magnetically coupled wireless power transfer system (WPT) in the overall performance are analyzed quantitatively in terms of the effective quality factors of the loop resonators and coupling coefficient considering the slab losses, based on an equivalent circuit. Using the ideal metamaterial slab(lossless slab), the WPT efficiency is improved considerably by the magnetic flux focusing. However, the practical lossy slab made of RRs or SRRs limits the significant enhancement of WPT efficiency due to the relatively high losses in the slab consisting of RRs or SRRs near the resonant frequency. For the practical loop resonator, other than a point magnetic charge, using the practical lossy metamaterial slab in order to improve the transfer efficiency, the width of the slab needs to be optimized somewhat less than the half of the distance between two loop resonators. For the low-loss slab with its loss tangent of 0.001, the WPT efficiency is maximized at 93 % when the ratio of the slab width and the distance between the two resonators is approximately 0.35, compared with 53 % for the case without the slab. The efficiency in case of employing the high-low slab(loss tangent: 0.2) is maximized at 61 % when the slab ratio is 0.25.

• Journal of Navigation and Port Research
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• v.46 no.3
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• pp.179-190
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• 2022

In this study, we investigated the characteristic impedance and bandwidth of CPW3DCS (coplanar waveguide employing periodic 3D coupling structures), and examined its potential for the development of a marine radio communication FISoC (fully-integrated system on chip) semiconductor device. To extract bandwidth and characteristic impedance of the CPW3DC, we induced a measurement-based equation reflecting measured insertion loss, and compared the measured results of the propagation constant β and characteristic impedance with the measured ones. According to the results of the comparison, the calculated results show a good agreement with the measured ones. Concretely, the propagation constant β and characteristic impedance exhibited an maximum error of 3.9% and 6.4%, respectively. According to the results of this study, in a range of LT = 30 ~ 150 ㎛ for the length of periodic structures, the CPW3DC exhibited a passband characteristic of 121 GHz, and a very small dependency of characteristic impedance on frequency. We could realize a low impedance transmission line with a characteristic impedance lower than 20 Ω by using CPW3DCS with a line width of 20 ㎛, which was highly reduced, compared with a 3mm line width of conventional transmission line with the same impedance. The characteristic impedance was easily adjusted by changing LT. The above results indicate that the CPW3DC can be usefully used for the development of a wireless communication FISoC (fully-integrated system on chip) semiconductor device. This is the first report of a study on the bandwidth of the CPW3DC.

• Elastomers and Composites
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• v.22 no.3
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• pp.204-212
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• 1987

The purpose of this study is to investigate the reinforced effect between MGF treated silane coupling agents and rubber matrix under the configuration chemical bonds, also the effect of triazine thiol compounds. For this study, vulcanizates were prepared with fifteen different compounding formulas. Their vulcanization characteristics, physical properties were examined by means of the ODR(Oscillating Dist Rheometer), the tensile tester, the benzene swelling test. The results of this study obtained are as follows: 1. In the ODR test, the MA vulcanizate was the fastest one in terms of having reached to optimum cure time($t_{90}$) and, with the same formula, when MGF vulcanizates, the shortest optimum cure times has appeared. 2. The SA, SC vulcanizates were the best the other in the physical properties such as 100%modulus, 200%modulus, 300%modulus, tensile strength. The SB vulcanizate, with higher density of crosslinking than other vulcanizates. The vulcanizates, which were filled with MGF treated with silane coupling agents we were the higher density of crosslinking than vulcanizates filled with MGF only. 3. In aging properties, the silica vulcanizates appeared to be better than the other vulcanizates. The aging Properties of treated MGF vulcanizates were similar to the silica vulcanizates. The(CR+APS+silica) and(CR+APS+MCF) were easily crosslinked by exposure to the air, and the physical properties have been improved.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.3 s.118
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• pp.323-333
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• 2007

In this paper, a new MDAS-DR antenna structure designed to efficiently shape a flat-topped radiation pattern is proposed. The antenna structure is composed of a stacked micro-strip patch exciter and a multi-layered disk array structure(MDAS) surrounded by a dielectric ring. The MDAS, which was supplied by a stacked microstrip patch exciter with radiating power, can form a flat-topped radiation pattern in a far field by a mutual interaction with the surrounding dielectric ring. Therefore, the design parameters of the dielectric ring and the MDAS structure are important design parameters for shaping a flat-topped radiation pattern. The proposed antenna used twelve multi-layered disk array elements and a Teflon material with a dielectric constant of 2.05. An antenna operated at 10 GHz$(9.6\sim10.4\;GHz)$ was designed in order to verify the effectiveness of the proposed antenna structure. The commercial simulator of CST Microwave $Studio^{TM}$, which was adapted to a 3-D antenna structure analysis, was used for the simulation. The antenna breadboard was also fabricated and its electrical performance was measured in an anechoic antenna chamber. The measured results of the antenna breadboard with a flat-topped radiation pattern were found to be in good agreement with the simulated one. The MDAS-DR antenna gain measured at 10 GHz was 11.18 dBi, and the MDAS-DR antenna was capable of shaping a good flat-topped radiation pattern with a beam-width of about $40^{\circ}$, at least within a fractional bandwidth of 8.0 %.

• Archives of design research
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• v.13 no.1
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• pp.209-218
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• 2000

The purpose of this study was to improve the curriculum for industrial design department in the junior colleges. In order to achieve the purpose, two methodologies were carried out. First is job analysis of the industrial designers who have worked in the small & medium manufacturing companies, second is survey for the opinions of professors in the junior colleges. Some results were as follows: 1. The period of junior college for industrial designers is 2 years according to present. But selectively 1 year of advanced course can be established. 2. The practice subjects same as computational formative techniques needed to product development have to be increased. In addition kinds of selection subjects same as foreign language, manufacturing process, new product information and consumer behavior investigation have to be extended. 3. The next subjects need to adjust the title, contents and hours. (1) The need of 3.D related subjects same as computer modeling, computer rendering, 3.D modeling was high. The use of computer is required to design presentation subjects. (2)The need of advertising and sale related subjects same as printing, merchandise, package, typography, photography was low, the need of presentation techniques of new product development was high. (3) The need of field practice, special lecture on practice and reading original texts related subjects was same as at present, but these are not attached importance to form. As the designers feel keenly the necessity of using foreign language, the need of language subject was high.

• Korean Journal of Soil Science and Fertilizer
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• v.32 no.4
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• pp.429-439
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• 1999

Potentiometric titration data were collected for some humic acids purified from Korean upland and paddy soils over a range of pH (3.0 - 11.0) with $NaNO_3$ background electrolyte concentrations (0.01, 0.10, 0.50 and 1.00 M). The data were applied to model A and V which included both intrinsic heterogeneity of humic materials and electrostatic interaction influences on binding sites. The elemental analysis were conducted for various type of humic samples. The $E_4/E_6$ ratio proposed negative correlation with the total carboxyl groups ($r^2$= 0.9988). The charge ($cmol_c\;kg^{-1}$) on the humic acids became more negative as the ionic strength increased. In both continuous and batch titrations, the ionic strength effect was greater in Namweon series (pH 6.39) than others at pH 5.00. The effect of ionic strength on surface charge appears to be greater in batch titrations. This could suggest that continuous titrations do not represent an equilibrium state and the effects of electrolyte concentration was not fully realized during the course of titrations. Both models described experimental data obtained from continuous and batch titrations well over a range of ionic strengths. Model A is more simpler than model V but adaptes more fitted parameters. Thus, the observed change in apparent binding constants with surface charge is regarded solely due to electrostatic influences rather than functional group heterogeneity. However, Model V is more mechanistically realistic in a number of discrete ligand binding sites.