• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.7
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• pp.534-538
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• 2013

We propose a generic method to calculate the optical functionalities of a 3D display with a lenticular lens array. In the present work, based on the geometrical optics, it is designed considering the specifications of the display panel. For the effective simulation, we first calculate the optical functionalities of a single cylindrical lens and, by comparing with the results obtained from the conventional geometrical optics, confirm the validity of the present method. Afterwards, we obtain the full distribution of the light intensity at an optimum viewing distance by expanding the results of the single lens to the horizontal plane of the display panel. From these results, we finally confirm whether the 3D images are realized or not in the system.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.11
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• pp.951-956
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• 2013

This paper describes techniques used to analyze the sweet spot of sound field reproduced by ear-level linear arrays of loudspeakers by geometrical approach method. Previous researches have introduced various sweet spot definitions in their own way. In general, sweet spot is defined as an area whose stereophonic sound effect is valid. Its size is affected by the geometrical arrangement of the system. In this paper, a case when plane waves are generated by linear arrays of loudspeakers in the horizontal plane is considered. So the sweet spot is defined as an area in which the listener can perceive the desired azimuth angle. Because there are many loudspeakers, impulse responses at listener's ears are in the form of pulse-train and the time-duration of the pulse-train affects the localization performance of the listener. So we calculated the maximum time duration of pulse-train by geometrical approach method and identified with the results of impulse response simulation. This paper also includes parameter analysis with respect to aperture size, so it suggests a tool for sound engineers to expect the sweet spot size and listener's sound perception.

• New & Renewable Energy
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• v.20 no.1
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• pp.102-109
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• 2024

The Typical Meteorological Year (TMY) dataset compiles 12 months of data that best represent long-term climate patterns, focusing on global horizontal irradiance and other weather-related variables. However, the irradiance measured on the plane of the array (POA) shows certain distinct distribution characteristics compared with the irradiance in the TMY dataset, and this may introduce some biases. Our research recalculated POA irradiance using both the Isotropic and DIRINT models, generating an updated dataset that was tailored to POA characteristics. Our analysis showed a 28% change in the selection of typical meteorological months, an 8% increase in average irradiance, and a 40% reduction in the range of irradiance values, thus indicating a significant shift in irradiance distribution patterns. This research aims to inform stakeholders about accurate use of TMY datasets in potential decision-making. These findings underscore the necessity of creating a typical dataset by using the time series of POA irradiance, which represents the orientation in which PV panels will be deployed.

• Journal of the Korea Society of Computer and Information
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• v.27 no.3
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• pp.71-77
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• 2022

In this paper, we propose 1×2 array antenna with dual linear polarization characteristics for mmWave band operation. The proposed antenna is designed two microstirp feeding structure and FR-4 substrate, which is thickness 0.4 mm, and the dielectric constant is 4.3. The size of 1×2 array antenna is 2.33 mm×2.33 mm, and total size of array antenna is 13.0 mm×6.90 mm. From the fabrication and measurement results, bandwidths of 1.13 GHz (28.52~29.65 GHz) for port 1 and 1.08 GHz (28.45~29.53 GHz) for port 2 were obtained based on the impedance bandwidth. Cross polarization ratios are obtained from 7.68 dBi to 16.90 dBi in case of vertical polarization, and from 7.46 dBi to 15.97 dBi in case of horizontal polarization for input port 1, respectively. Also, cross polarization ratios are obtained from 8.59 dBi to 13.72 dBi in case of vertical polarization and from 9.03 dB to 14.0 dB in case of horizontal polarization for input port 2, respectively.

• The Journal of the Acoustical Society of Korea
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• v.41 no.4
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• pp.397-409
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• 2022

A model is developed for the calculation of sea surface generated ambient noise in the range dependent ocean environment. The sources are located in the horizontal plane all around and their depths are at the near-surface. The receiver array is located in the range dependent ocean waveguide. One-way coupled mode method is used to model the acoustic propagation between the sources and receiver in the range dependent waveguide, and the cross spectral density matrix of noise is derived. In simulation, noise intensity, beamforming result and coherence function are calculated from the cross spectral density matrix. These results are compared with those in the range independent environment. The modeling result shows the effect of the vertical directionality and asymmetry characteristics of the horizontal plane.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.2
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• pp.144-150
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• 2012

In this paper, circularly polarization patch array antenna of RSE(Road-side Equipment) base station for DSRC(Dedicated Short Range Communication) of ITS(Intelligent Transport System) is proposed. The antenna of RSE base station for DSRC is designed to operate circularly polarization to receive reflected signal from multiplex path effectively. The proposed antenna consisted of microstrip patch and feed line, the slit is inserted in the proximity of the slot of feed structure to generate circularly polarization. The $2{\times}2$ array structure is designed to satisfying gain that DSRC RSE base station antenna required. Measured impedance bandwidth and axial-ratio bandwidth are satisfied by all DSRC band of 5.795~5.855 GHz. Vertical and horizontal HPBW of the proposed antenna are both about 43 degrees, it showed gain characteristic of about 11.21 dBi.

• Aerospace Engineering and Technology
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• v.11 no.2
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• pp.1-11
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• 2012

This paper describes the transmit/receive(T/R) module for the space based X-band active phased array radar. T/R module is the integrated module which is assembled by the transmitting and receiving RF semiconductor devices to enable the electronically beam steering of the phased array antenna and the key component of the SAR payload. T/R module can selectively receive the polarization signals by the switch according to the established technology but now the technological trend of the T/R module is to receive the horizontal and vertical polarization signal simultaneously. Therefore the research and development of the dual polarization receiving channel T/R module is actively in progress. In this study, as the prior research for the next generation SAR payload, the technological trend of the active phased array radar T/R module and the result of the preliminary design of the dual receiving channel T/R module were described.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.8
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• pp.830-838
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• 2003

In this paper, TX/RX dual operation microstrip single antenna for satellite communication is designed, analyzed, fabricated and measured. TX/RX frequency ranges are 14.0∼l4.5 GHz, 11.7∼12.75 GHz in respectively and vertical and horizontal polarizations are used for TX and RX. This antenna uses microstrip direct feeding for RX and aperture coupled strip-line feeding for TX and accommodates stacked elements for a high directivity and wide impedance bandwidth. In an analysis of single element, FDTD and MOM was compared and FDTD analysis was more accurate because of the consideration of finite structure and imperfect two ground planes. The proposed structure facilitates generally to an extension of two dimensional array and lower an unwanted radiation by strip-line feed in TX. TX/RX 8${\times}$4 array has a return loss below -10 dB, -14 dB in TX, RX respectively and a gain ranging from 19.1∼20.7 dB in TX, 21.2∼21.8 dB in RX which has a radiation efficiency of 43∼5l %, 52∼57 %.

• Journal of Welding and Joining
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• v.33 no.5
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• pp.47-52
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• 2015

In this study, it was tried to analyze the effects of welding parameters on the weld penetration and aspect ratio when a STS316L pipe was welded in a horizontal position by GTAW. Experiments were systematically designed using a L18 orthogonal array, and the effects of welding parameters were statistically analyzed by ANOVA(Analysis of Variance). The shielding gas type has the largest effect on both the penetration and aspect ratio. The welding current type and shielding gas flow rate have a little effect on the penetration, whereas the electrode tip angle has a little effect on the aspect ratio. When welded at a selected welding condition, which is composed of He shielding gas, pulse current of 300/45 A, electrode tip angle of 90o, and shielding gas flow rate of 30 l/min, the estimated interval at least 95 % confidence was $1.99{\pm}0.18mm$ for the penetration and $0.31{\pm}0.04$ for the aspect ratio. From the confirmation experiments, the average penetration and aspect ratio were well agreed with the estimation as 1.96 mm and 0.30, respectively. Additionally, the effects of the welding speed and welding current on the penetration and aspect ratio were experimented and analyzed by linear regression. The penetration was linearly increased with the decrease of the welding speed and with the increase of the welding current, but the aspect ratio showed a tendency to a little decrease with the increase of both the welding speed and current.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.3
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• pp.78-86
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• 2017

In this paper, we propose hidden object detection system using parametric array based on acoustic signal that is harmless to human body. A transmit signal of the proposed detection system uses a high directive chirp signal generated from parametric array phenomenon, which uses technique to improve a signal to noise (SNR) of a received signal and a distance resolution trough the dechirp processing. The transmit sensor array is constructed as $8{\times}2$ and has a horizontal beam width of $7^{\circ}$ and vertical beam width of $26^{\circ}$. To verify the detection and visualization of the proposed system, a 2-axis driving control system based on linear stage was constructed, and A-scan, B-scan, and C-scan experiments was addressed for hidden object. From experimental results, we detected and visualized the hidden bronze plate and pipe by cloth and the visualized shapes was confirmed. Especially, the obtained errors was $0.015m^2$ for bronze plate, and $0.046m^2$ for pipe.