• The Journal of the Convergence on Culture Technology
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• v.9 no.6
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• pp.919-925
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• 2023

Modern drones are equipped with miniaturized mission equipment capable of performing various tasks such as surveillance and reconnaissance. Consequently, these mission equipment are exposed to disturbances like wind loads and motor rotations, which can lead to instability in the operation of the Electro-Optical Targeting System (EOTS). Specifically, simple step inputs for changing the line of sight in EOTS can cause abrupt changes in speed, inducing overshoot and potentially creating instability along with other disturbances. To address this, a velocity profile was designed so that the angular velocity moves in a trapezoidal shape when changing the EOTS line of sight. A Double-loop controller was designed to apply this profile as an input to the external loop receiving position feedback. The system's stability was then compared, and the velocity profile was optimized within a stable range by varying maximum speed and acceleration.

• International Journal of Computer Science & Network Security
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• v.24 no.2
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• pp.53-58
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• 2024

This paper presents a novel miniaturized 3-D cubic antenna for use in wireless sensor network (WSN) application. The geometry of this antenna is designed as a cube including a meander dipole antenna. A truly omnidirectional pattern is produced by this antenna in both E-plane and H-plane, which allows for non-intermittent communication that is orientation independent. The operating frequency lies in the ISM band (centered in 2.45 GHz). The dimensions of this ultra-compact cubic antenna are 1.25*1.12*1cm3 which features a length dimension λ/11. The coefficient which presents the overall antenna structure is Ka=0.44. The cubic shape of the antenna is allowing for smart packaging, as sensor equipment may be easily integrated into the cube hallow interior. The major constraint of WSN is the energy consumption. The power consumption of radio communication unit is relatively high. So it is necessary to design an antenna which improves the energy efficiency. The parameters considered in this work are the resonant frequency, return loss, efficiency, bandwidth, radiation pattern, gain and the electromagnetic field of the proposed antenna. The specificity of this geometry is that its size is relatively small with an excellent gain and efficiency compared to previously structures (reported in the literature). All results of the simulations were performed by CST Microwave Studio simulation software and validated with HFSS. We used Advanced Design System (ADS) to validate the equivalent scheme of our conception. Input here the part of summary.

• Journal of the Korean Institute of Gas
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• v.28 no.1
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• pp.59-64
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• 2024

In this study, we conducted research on a miniaturized transmission system suitable for ultra-compact electric vehicles, such as electric arts or small electric cars. While conventional electric vehicles eliminate multi-gear transmissions and control motor output or secure initial driving force through reducers, in vehicles like electric karts or compact electric cars, which have relatively small battery capacities, the driving range can be reduced or the motor can be stressed epending on the loading state. Therefore, in this study, we developed a low stage ratio 0.625 and high stage ratio 1.6 a two-stage transmission system that can change gears as needed, considering factors such as slope conditions and loading status, by applying the continuously variable transmission (CVT) mechanism. Based on the selected gear ratios, we designed the transmission and created a test rig to verify the power transmission efficiency of the developed transmission. Using the test rig, we varied the rotational speed and load of the transmission to confirm its power transmission characteristics and also examined the heat generation characteristics during shifting and operation. As a result, developed a two-stage transmission with a CVT structure.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.2
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• pp.192-201
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• 2003

In this paper, to reduce the size of patch, three types of 3-dimensional patch antennas which are one-directionally-corrugaged type, rectangular ring-likely corrugated type, and lattice-likely corrugated type rectangular microstrip patch antennas(MPA) are designed and fabricated at the 1.575 GHz. As the result, one-directionally corrugated rectangular MPA is reduced in the resonant length of patch by 21.4% than that of general plane MPA. -10 dB bandwidth(B.W) is 62 MHz(3.9 %) and this is broader than that(39 MHz, 2.5 %) of plane MPA by 23 MHz(1.5 %). The gain is 5.8 dBd and this is reduced by 0.9 dB than that(6.7 dBd) of plane MPA. Half power beamwidth(HPBW) is broadened by 18$^{\circ}$ than that of plane MPA in the E-plane and this is due to the reduced length of patch. For rectangular ring-likely corrugated retangular MPA, the patch size is miniaturized by 21.6 % than that of plane MPA. For lattice-likely corrugated rectangular MPA, in the linear polarization, the size of patch is miniaturized by 43.3 % than that of plane MPA. -10 dB B.W is 70 MHz(4.4 %) and this is broadened than that of plane MPA by 31 MHz(2 %). Gain is 2.2 dBd and this is smaller than that of plane MPA by 4.5 dB. HPBW is increased in both E-plane and H-plane by 22$^{\circ}$ and 13$^{\circ}$, respectively. For circular polarization, the size of patch is reduced by 41 % than that by 41 %. The axial ratio(AR) is 0.8 dB at the 1.575 GHz and the axial ratio bandwidth(ARBW) within 2 dB is 20 MHz(1.27 %) and this is increased by 10 MHz(0.63 %) than that 10 MHz(0.63 %) of plane MPA. From all the results above, it is conformed that the proposed antenna has merit in size reduction of patch and in the input impedance B.W, and is more profitable in many application than the general plane type MPA.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.3
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• pp.219-232
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• 2013

This paper presents a microstrip antenna which recovers its resonant frequency and impedance shifted automatically by the approach of other objects such as hands. This can be used for telemetry sensor applications in the ultrahigh frequency(UHF) industrial, scientific, and medical(ISM) band. It is the key element that an frequency-reconfigurable antenna could be electrically controlled. This antenna is miniaturized by loading the folded plates at both radiating edges, and varactor diodes are installed between the radiating edges and the ground plane to control the resonant frequency by adjusting the DC bias asymmetrically. Using this voltage-controlled antenna and the micro controller peripheral circuits of reading the returned level, the antenna is designed and fabricated which recovers its resonant frequency and impedance automatically. Designed frequency auto recovering antenna is conformed to be recovered within a few seconds when the resonant frequency and impedance are shifted by the approach of other objects such as hand, metal plate, dielectric and so on.

• Journal of the Korean Society for Nondestructive Testing
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• v.18 no.5
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• pp.381-388
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• 1998

The ultrasonic method, which is well known as non-destructive test method, is widely used to evaluate the material damage caused by degradation practically. However, this method is just used for measuring the crack size and the thickness loss of tube. The purpose of this study is to investigate the applicability of the ultrasonic technique for the evaluation of carburized material and to suggest the correlations between the ultrasonic characteristics and carburized degradation. The miniaturized specimens($40{\times}20{\times}6.3mm$) are adopted from the HK-40 (25Cr-20Ni-0.4C) centrifugal cast tube after carburization treatment. Carburization was carried at $1200^{\circ}C$ by the pack method. The results of ultrasonic test present that the longitudinal wave velocity increased with the increase of carburized depth. The correlation between the longitudinal wave velocity and carburization was changed with the density and Young's modulus. Therefore, the average velocity in the materials carburized for 336 hours and the unused one were 5,840 m/s and 5,755 m/s at 5 MHz, respectively. With the obtained results from this study, it can be recognized that the technique using the ultrasonic velocity property is very useful method to evaluate the degree of carburized material non-destructively.

• Convergence Security Journal
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• v.14 no.6_1
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• pp.129-138
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• 2014

South Korea should correspond to the primary threat to North Korea's nuclear weapons. It is necessary to have countermeasures to solve the realistic problems of North Korea's nuclear weapons. We can intensify military pact between the United States and Korea and at the same time strengthening the current military power. Currently, we take note the threat North Korea's missile. We can not control the development of a nuclear weapon and there are possibilities that North Korea have successfully miniaturized nuclear enough to carry by the missile. We should overview and check the Korea's missile defenses system. While the direction of the overall missile defense system deployment with a focus on lower and upper air defense network. And discuss defense research should be to build a system that can be protected with a key strategic facilities and cities. While North Korea have nuclear weapon, the main issues related to North Korea's nuclear threat. The six party talks countries try to solve the problem by the international and diplomatic approach. At the same time we should make somewhat to defend measures such as military defenses of Kill chain system to protect our country. Kill Chain is on of the effective defense system. We know that North Korea do not abandon to develop nuclear weapons by diplomatic efforts. We should performed in fact by a variety of military suppression method.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.5 s.96
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• pp.526-533
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• 2005

In this paper, the miniaturized the linear polarization and the circular polarization microstrip antennas, which are the two ends in the resonance length direction or all the four-ends were folded are designed and fabricated at the resonant frequency of 1.575 GHz(fur GPS system). For the linear polarization microstrip antenna, the antenna was bent. downward so that the visible length(=L) was reduced by $31.7\%(\varepsilon_r=1.06)$. The folded antenna was folded toward the center of the antenna once again. In this case, the visible length reduction rate, gain, -10 dB bandwidth, E-plane and H-plane HPBW were $73.9\%$, 5.12 dBd, $64MHz(4\%),\;151^{\circ}\;and\;79.2^{\circ}$, respectively. For the circular polarization microstrip antenna, the folded structure of the linear polarization antenna was applied to all the few directions. For the most efficiency the folded bottom surfaces were designed in a triangular shape. In this case, the visible area reduction rate, gain, -10 dB bandwidth, and HPBW in horizontal polarization of the z-x plane and the z-y plane were $71.5\%,\;3.96dBd,\;84MHz(5.3\%),\;80.6^{\circ}\;and\;82.1^{\circ}$, respectively. Therefore, we have confirmed that the folded structure is suitable fer the miniaturization of the microstrip antenna.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.5 s.96
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• pp.501-510
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• 2005

In this paper, the miniaturized linear and circular polarization microstrip antennas are designed and fabricated at the resonant frequency of 1.575 GHz. To miniaturize the microstrip patch antenna(MPA), the 'L' type plates are attached under the rectangular microstrip patch. In case of the linear polarization, the size of the microstrip antenna attached the 14 plates is reduced to $67.9\%(47mm{\times}47mm)$ compared with general $MPA(83mm{\times}83mm)$. The return loss and -10 dB bandwidth are -34.4 dB and 49 $MHz(3.1\%)$. And the radiation pattern is broad through the size reduction of the patch. Also in case of the circular polarization, the size of the microstrip antenna with 13 plates is reduced to $54.6\%(53mm{\times}54mm)$ compared with the general $MPA(76mm{\times}83mm)$. The axial ratio is 1.37dB at 1.575 GHz, the 2 dB axial ratio bandwidth is 14 $MHz(0.8\%)$. As that result, we could confirm that 3-dimensional structure with attached 'L' shaped plate is proper form for the miniaturization of linear and circular polarization microstrip antenna.

• Journal of the Korea Convergence Society
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• v.8 no.8
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• pp.9-15
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• 2017

With the development of semiconductor integration technology, central processing units and storage devices have been miniaturized and performance has been rapidly developed, interconnection network technology is becoming a more important factor in terms of the performance of high performance computing system. In this paper, we analyze the trend of interconnection network technology used in high performance computing. Interconnect technology, which is the most widely used in the Supercomputer Top 500(2017. 06.), is an Infiniband. Recently, Ethernet is the second highest share after InfiniBand due to the emergence of 40/100Gbps Gigabit Ethernet technology. Gigabit Ethernet, where latency performance is lower than InfiniBand, is preferred in cost-effective medium-sized data centers. In addition, top-end HPC systems that demand high performance are devoting themselves from Ethernet and InfiniBand technologies and are attempting to maximize system performance by introducing their own interconnect networks. In the future, high-performance interconnects are expected to utilize silicon-based optical communication technology to exchange data with light.