• Journal of IKEEE
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• v.19 no.4
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• pp.566-572
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• 2015

In this paper, we calculate monostatic RCS(Radar Cross Section) and bistatic RCS for improving the Performance of the skin tracking of KSLV-II and the results were compared. EM(Electromagnetic) simulator was used for numerical analysis. For the two paths(L, S), after the vehicle was launched, RCS was calculated for region from 280 to 400 seconds. In the case of using the bistatic radar system, when the vehicle was launched to the L path, tracking performance was better when we receive RCS in Jeju than in Goheung. When the vehicle was launched to the S path, tracking performance was better when we receive RCS in Goheung than in Jeju. In the case of using the monostatic radar system, when the vehicle was launched to the L path, tracking performance was better when we receive RCS in Goheung than in Jeju. When the vehicle was launched to the S path, tracking performance was better when we receive RCS in Jeju than in Goheung.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.276-276
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• 2010

Localized surface plasmon resonance (LSPR) has been explored recently as a promising approach to increase energy conversion efficiency in photovoltaic devices, particularly for thin film hydrogenated amorphous silicon (a-Si:H) solar cells. The LSPR is frequently excited via an electromagnetic (EM) radiation in proximate metallic nanostructures and its primary con sequences are selective photon extinction and local EM enhancement which gives rise to improved photogeneration of electron-hole (e-h) pairs, and consequently increases photocurrent. In this work, high-dielectric-constant (k) $ZrO_2$ (refractive index n=2.22, dielectric constant $\varepsilon=4.93$ at the wavelength of 550 nm) is proposed as spacing layer to enhance the LSPR for application to the thin film silicon solar cells. Compared to excitation of the LSPR using $SiO_2$ (n=1.46, $\varepsilon=2.13$ at the wavelength of 546.1 nm) spacing layer with Au nanoparticles of the radius of 45nm, that using $ZrO_2$ dielectric shows the advantages of(i) ~2.5 times greater polarizability, (ii) ~3.5 times larger scattering cross-section and ~1.5 times larger absorption cross-section, (iii) 4.5% higher transmission coefficient of the same thickness and (iv) 7.8% greater transmitted electric filed intensity at the same depth. All those results are calculated by Mie theory and Fresnel equations, and simulated by finite-difference time-domain (FDTD) calculations with proper boundary conditions. Red-shifting of the LSPR wavelength using high-k $ZrO_2$ dielectric is also observed according to location of the peak and this is consistent with the other's report. Finally, our experimental results show that variation of short-circuit current density ($J_{sc}$) of the LSPR enhanced a-Si:H solar cell by using the $ZrO_2$ spacing layer is 45.4% higher than that using the $SiO_2$ spacing layer, supporting our calculation and theory.

• Journal of the Korean Society of Industry Convergence
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• v.24 no.6_2
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• pp.729-735
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• 2021

Recently Artificial Intelligence(AI) has been developed and used in various fields. Especially AI recognition technology can perceive and distinguish images so it should plays a significant role in quality inspection process. For stability of autonomous driving technology, semiconductors inside automobiles must be protected from external electromagnetic wave(EM wave). As a shield film, a thin polymeric material with hole shaped micro-patterns created by a laser processing could be used for the protection. The shielding efficiency of the film can be increased by the hole structure with appropriate pitch and size. However, since the sensitivity of micro-machining for some parameters, the shape of every single hole can not be same, even it is possible to make defective patterns during process. And it is absolutely time consuming way to inspect all patterns by just using optical microscope. In this paper, we introduce a AI inspection system which is based on web site AI tool. And we evaluate the usefulness of AI model by calculate Area Under ROC curve(Receiver Operating Characteristics). The AI system can classify the micro-patterns into normal or abnormal ones displaying the text of the result on real-time images and save them as image files respectively. Furthermore, pressing the running button, the Hardware of robot arm with two Arduino motors move the film on the optical microscopy stage in order for raster scanning. So this AI system can inspect the entire micro-patterns of a film automatically. If our system could collect much more identified data, it is believed that this system should be a more precise and accurate process for the efficiency of the AI inspection. Also this one could be applied to image-based inspection process of other products.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.3
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• pp.227-247
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• 2015

An X-band $8{\times}16$ dual-polarized active phased array antenna system has been implemented based on the substrate integrated waveguide(SIW) technology having low propagation loss, complete EM shielding, and high power handling characteristics. Compared with the microstrip case, 1 dB less is the measured insertion loss(0.65 dB) of the 16-way SIW power distribution network and doubled(3 dB improved) is the measured radiation efficiency(73 %) of the SIW sub-array($1{\times}16$) antenna element. These significant improvements of the power division loss and the radiation efficiency using the SIW, save more than 30 % of the total power consumption, in the active phased array antenna systems, through substantial reduction of the maximum output power(P1 dB) of the high power amplifiers. Using the X-band $8{\times}16$ dual-polarized active phased array antenna system fabricated by the SIW technology, the main radiation beam has been steered by 0, 5, 9, and 18 degrees in the accuracy of 2 degree maximum deviation by simply generating the theoretical control vectors. Performing thermal cycle and vacuum tests, we have found that the SIW array antenna system be eligible for the space environment qualification. We expect that the high efficiency SIW array antenna system be very effective for high performance radar systems, massive MIMO for 5G mobile systems, and various millimeter-wave systems(60 GHz WPAN, 77 GHz automotive radars, high speed digital transmission systems).

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.7
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• pp.727-732
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• 2008

Recently, according to the increase of using the microwave equipments, the interests in effects on human body have been also increased. For example, there have been many researches on making the standard the specific absorbing ratio (SAR) caused by mobile phones. However, it is needed to study on the induced current on human body caused by HF(Hight Frequency) band which can deeply penetrate the human body. Especially, since the RFID systems are applied to the transportation card and the library, it is hooded to research on the effect on human body exposed to the radiated power from the RFID system. In this paper, we designed a cylindrical monopole antenna model of human body exposed to 13.56 MHz RFID system, which can model the induced current on human body. To verify the proposed equivalent antenna model, we compared the induced currents between human body and the equivalent antenna model.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.9
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• pp.661-667
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• 2018

Tactical communication radio systems that employ software defined radios(SDRs) have been developed for achieving high-speed data transmissions and voice communications. Such systems possess multiband and multichannel features, and can potentially replace several existing radio systems. This paper proposes a design for wideband antennas by incorporating a diplexer matching network for tactical vehicles. The proposed antenna design includes two radiators(upper and lower) and a diplexer matching network connected to the end of the feed line such that the LC matching networks are interleaved in the lower radiator and spring mount. By employing the diplexer matching network, the designed antenna can perform wideband impedance matching for the fifty ohm feed line. The designed LC networks aid in varying the effective electrical length of the antenna according to the operation frequency. The primary objective behind adjusting the electrical length is to vary the current distribution above and below the LC networks. The proposed antenna was fabricated and tested in an open site. The obtained evaluation results show that the designed antenna can achieve a relative bandwidth of 190% with a VSWR value of 3.5:1, and can attain good antenna gains over VHF and UHF bands.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.46 no.6
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• pp.44-49
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• 2009

EAS (electronic article surveillance) systems have increased rapidly for article surveillance. In this paper, the strength of the EMF (electromagnetic fields) of EAS systems were measured. Pacemaker and ICD were investigated for inappropriate response resulting from EM (electromagnetic) EAS systems. The strength of EMF and the response of pacemaker and ICD were measured in the inner left side, outer right sides and the center of gates of the 6.3 kHz and 14.25 kHz EAS systems at a height of 130cm. As the result, EMF of the EAS system using 14.25 kHz was stronger than that of 6.3 kHz. AU interferences were observed only for 14.25 kHz, and the noisy ECG was found in three static positions on the pacemaker. The ICD resulted in noise reversion and VF (ventricular fibrillation) both static and moving positions by the EMP of 14.25 kHz EAS system. Therefore, it is necessary to post a message warning radiation of EMF from every EAS systems and possible risk of pacemakers and ICDs.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.7
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• pp.671-677
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• 2013

In this paper, we propose a method of near-field analysis for vehicle LF antennas in order to estimate the accurate reading range of a smart key. The LF antenna consists of a ferrite core and a conducting wire which is coated with polyethylene for insulation, and it is mounted at the rear bumper frame of a commercial vehicle. The reading range of a smart key is measured at nine azimuthal directions distributed around the rear bumper, and then, the received power at each maximum reading range is measured by using a spectrum analyzer. The measurement shows that the maximum reading range exists between 1.38 m and 1.53 m, and the radiated power is between -83.6 dBmW and -75.0 dBmW. We further conducted EM simulation to estimate the reading range and the received power under the same condition that we applied for the measurement. The results demonstrate that an accurate reading range and received power can be achieved by simulation.

• Geophysics and Geophysical Exploration
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• v.25 no.1
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• pp.26-37
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• 2022

Recently, multiple methods using small aircraft for geophysical exploration have been suggested as a result of the development of information and communication technology. In this study, we introduce the hybrid unmanned aircraft electromagnetic system of the Korea Institute of Geosciences and Mineral resources, which is under development. Additionally, data processing and interpretation methods are suggested via the analysis of datasets obtained using the system under development to verify the system. Because the system uses a three-component receiver hanging from a drone, the effects of rotation on the obtained data are significant and were therefore corrected using a rotation matrix. During the survey, the heights of the source and the receiver and their offsets vary in real time and the measured data are contaminated with noise. The noise makes it difficult to interpret the data using the conventional method. Therefore, we developed a recurrent neural network (RNN) model to enable rapid predictions of the apparent resistivity using magnetic field data. Field data noise is included in the training datasets of the RNN model to improve its performance on noise-contaminated field data. Compared with the results of the electrical resistivity survey, the trained RNN model predicted similar apparent resistivities for the test field dataset.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.185.2-185.2
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• 2016

The plasma density is an essential plasma parameter describing plasma physics. Furthermore, it affects the throughput and uniformity of plasma processing (etching, deposition, ashing, etc). Therefore, a novel technique for plasma density measurement has been attracting considerable attention. Microwave probe is a promising diagnostic technique. Various type of cutoff, hairpin, impedance, transmission, and absorption probes have been developed and investigated. Recently, based on the basic type of probes, modified flat probe (curling and multipole probes), have been developing for in situ processing plasma monitoring. There is a need for comparative study between the probes. It can give some hints on choosing the reliable probe and application of the probes. In this presentation, we make attempt of numerical study of different kinds of microwave probes. Characteristics of frequency spectrum from probes were analyzed by using three-dimensional electromagnetic simulation. The plasma density, obtained from the spectrum, was compared with simulation input plasma density. The different microwave probe behavior with changes of plasma density, sheath and pressure were found. To confirm the result experimentally, we performed the comparative experiment between cutoff and hairpin probes. The sheath and collision effects are corrected for each probe. The results were reasonably interpreted based on the above simulation.