• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.1
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• pp.13-22
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• 2022

In this paper, we propose single and array antenna with dual linear polarization characteristics for 28 GHz band. The proposed antenna is designed two microstirp feeding structure and Taconic TLY-5 substrate, which is thickness 0.5 mm, and the dielectric constant is 2.2. The size of single patch antenna is 3.4 mm×3.4 mm, and total size of single antenna is 15.11 mm×15.11 mm. Also, the size of array antenna is 3.15 mm×3.15 mm, and total size of array antenna is 21.5 mm×13.97 mm. From the fabrication and measurement results, for 1×2 array antenna, in case of vertical polarization, cross polarization ratios are obtained from 14.23 dB to 20.79 dB and in case of horizontal polarization, cross polarization ratios are obtained from 14.31 dB to 22.74 dB for input port 1. in case of vertical polarization, cross polarization ratios are obtained from 15.75 dB to 25.88 dB and in case of horizontal polarization, cross polarization ratios are obtained from 14.70 dB to 22.82 dB for input port 2.

• 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.

• Journal of the Microelectronics and Packaging Society
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• v.30 no.4
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• pp.8-16
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• 2023

The importance of next-generation packaging technologies is being emphasized as a solution as the miniaturization of devices reaches its limits. To address the bottleneck issue, there is an increasing need for 2.5D and 3D interconnect pitches. This aims to minimize signal delays while meeting requirements such as small size, low power consumption, and a high number of I/Os. Hybrid bonding technology is gaining attention as an alternative to conventional solder bumps due to their limitations such as miniaturization constraints and reliability issues in high-temperature processes. Recently, there has been active research conducted on SiCN to address and enhance the limitations of the Cu/SiO₂ structure. This paper introduces the advantages of Cu/SiCN over the Cu/SiO₂ structure, taking into account various deposition conditions including precursor, deposition temperature, and substrate temperature. Additionally, it provides insights into the core mechanisms of SiCN, such as the role of Dangling bonds and OH groups, and the effects of plasma surface treatment, which explain the differences from SiO₂. Through this discussion, we aim to ultimately present the achievable advantages of applying the Cu/SiCN hybrid bonding structure.

• Journal of Advanced Technology Convergence
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• v.3 no.3
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• pp.9-15
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• 2024

This paper details research on the optimized design and fabrication of a 4x4 microstrip array antenna intended for X-Band applications. The study focuses on achieving the desired resonance frequency and gain by modifying the microstrip patch and array antenna parameters, including substrate type and patch size. It presents results from designing and fabricating a 4x4 array antenna with optimum substrate materials to enhance X-Band resonance characteristics and gain. The antenna dimensions are 10mm(W)x7.4mm(L)x 0.79mm(H), with an Rogers RO 4350B dielectric substrate (ε_r=3.54) and an inset-fed feeding method to minimize antenna size. Both the single patch and 4x4 array antennas demonstrated stable SWR (<1.5) and a gain of 18.5dBi at the target frequency of 10.3GHz in simulations. The fabricated antenna showed performance consistent with simulation results. This antenna design is suitable for X-Band applications, including military, satellite communications, and biomedical fields.

• Korean Journal of Food Science and Technology
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• v.52 no.5
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• pp.560-563
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• 2020

Cold plasma has been applied to improve quality of food product; however, studies on its effects on microbial and physicochemical qualities of rice noodles are rarely conducted. In this study, changes in the quality characteristics of rice noodles treated by cold plasma were determined. Cold plasma was generated in a square-shaped plastic container (250 W, 15 kHz, ambient air), and dielectric barrier discharge plasma treatments were applied to rice noodle samples for 0, 10, or 20 min. Rice noodles inoculated with either Bacillus cereus or Escherichia coli O157:H7 were subjected to plasma treatment for 20 min, and the approximate bacterial count reduction were 4.10 and 2.75 log CFU/g, respectively. The Hunter color values of the sample were increased after cold plasma treatment. Peroxide values and thiobarbituric acid reactive substance (TBARS) were increased with an increase in cold plasma treatment time. Futhermore, lipid oxidation was enhanced. Although further studies are warranted to evaluate changes in chemical qualities, such as lipid oxidation of rice noodles, induced by cold plasma, the results suggest that cold plasma can improve the microbial and physical qualities of rice noodles.

• Journal of Sensor Science and Technology
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• v.7 no.3
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• pp.154-162
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• 1998

A planar Bi-Sb multijunction thermal converter with high thermal sensitivity and small ac-dc transfer error has been fabricated by preparing the bifilar thin film Pt-heater and the hot junctions of thin film Bi-Sb thermopile on the $Si_{3}N_{4}/SiO_{2}/Si_{3}N_{4}$-diaphragm, which functions as a thermal isolation layer, and the cold junctions on the dielectric membrane supported with the Si-substrate, which acts as a heat sink, and its ac-dc transfer characteristics were investigated with the fast reversed dc method. The respective thermal sensitivities of the converter with single bifilar heater were about 10.1 mV/mW and 14.8 mV/mW in the air and vacuum, and those of the converter with dual bifilar heater were about 5.1 mV/mW and 7.6 mV/mW, and about 5.3 mV/mW and 7.8 mV/mW in the air and vacuum for the inputs of inside and outside heaters, indicating that the thermal sensitivities in the vacuum, where there is rarely thermal loss caused by gas, are higher than those in the air. The ac-dc voltage and current transfer difference ranges of the converter with single bifilar heater were about ${\pm}1.80\;ppm$ and ${\pm}0.58\;ppm$, and those of the converter with dual bifilar heater were about ${\pm}0.63\;ppm$ and ${\pm}0.25\;ppm$, and about ${\pm}0.53\;ppm$ and ${\pm}0.27\;ppm$, respectively, for the inputs of inside and outside heaters, in the frequency range below 10 kHz and in the air.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.33 no.2
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• pp.83-90
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• 2023

The β-Ga₂O₃ has the most thermodynamically stable phase, a wide band gap of 4.8~4.9 eV and a high dielectric breakdown voltage of 8MV/cm. Due to such excellent electrical characteristics, this material as a power device material has been attracted much attention. Furthermore, the β-Ga₂O₃ has easy liquid phase growth method unlike materials such as SiC and GaN. However, since the grown pure β-Ga₂O₃ single crystal requires the intentionally controlled doping due to a low conductivity to be applied to a power device, the research on doping in β-Ga₂O₃ single crystal is definitely important. In this study, various source powders of un-doped, Sn 0.05 mol%, Sn 0.1 mol%, Sn 1.5 mol%, Sn 2 mol%, Sn 3 mol%-doped Ga₂O₃ were prepared by adding different mole ratios of SnO₂ powder to Ga₂O₃ powder, and β-Ga₂O₃ single crystals were grown by using an edge-defined Film-fed Growth (EFG) method. The crystal direction, crystal quality, optical, and electrical properties of the grown β-Ga₂O₃ single crystal were analyzed according to the Sn dopant content, and the property variation of β-Ga₂O₃ single crystal according to the Sn doping were extensively investigated.

• Journal of Bio-Environment Control
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• v.11 no.1
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• pp.5-11
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• 2002

In this study, new development of natural ventilation window was accomplished to control environment of greenhouse with no use of farced ventilation during hot season. The ventilation effect of developed ventilation window was investigated in experimental greenhouse which was designed using side wall panel and folding type panel fur natural ventilation. Folding panel type ventilation window was designed to open upper part of the side wall and top of the roof using two hinges which are located bottom of the side wall and the roof panel to grab one side of each panels and guide the other side along with the guidance rail. Developed ventilation window has top ventilation part with maximum moving distance X=ι (1-cos$\theta$)=848.5 mm and side ventilation part with maximum moving distance Y=ι/2 $\times$sin$\theta$=1,184.4 mm at 45$^{\circ}$ of theoretical opening angle. It took 4.5 minutes to open roof vent fully and temperature at 1.2 and 0.8 m height decreased after 1 minute from starting opening and became equilibrium state maintaining 3-4$^{\circ}C$ difference after 2 minutes from complete opening. Air exchange rate was 15.2~39.3 h$^{-1}$ which was more than 10~15 h$^{-1}$ of continuous type and Venlo type greenhouse. The descent effect of temperature by ventilation windows was two times higher than Venlo type greenhouse.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.5 s.108
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• pp.461-475
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• 2006

In this paper, it is described about the tri-band mobile antenna system design to provide broadband multimedia and direct broadcasting services using goo-stationary Koreasat 3, simultaneously operated in Ka/K/Ku band. The radiating part of the antenna system with a fan beam characteristic in the elevation plane is composed of the quasi-offset dual shaped reflector and the tri-band feeder. The tri-band feeder is also composed of the Ka/K dual band feeder with the protruding dielectric rod, the circular polarizer, the ortho-mode transducer and the circular-polarized Ku band feed array. Especially, the Ka/K dual band circular polarizer was realized firstly using the comb-type structure. For fast satellite-tracking on the movement, the Ku band feed array has the structure of the $2{\times}2$ active phased array which can make electrical beams. And, the circular-polarized characteristic in the feed array was improved by $90^{\circ}$ rotating arrangement of four radiating elements polarized circularly by a $90^{\circ}$ hybrid coupler, respectively. Four beam forming channels to make electrical beams at Ku band are divided into the main beam channel and the tracking beam channel in the output, and noise temperature characteristics of each channel were analyzed on the basis of the contributions of internal sub_units. From the fabricated antenna system, the output power at $P_{1dBc}$ of Ka_Tx channel was measured more than 34.1 dBm and the measured noise figures of K/Ku_Rx channels were less than 2.4 dB and 1.5 dB, respectively, over the operating band. The radiation patterns with co- and cross-polarization in the tri-band were measured using a near-field measurement in the anechoic chamber. Especially, Ku radiation patterns were measured after correcting each initial phase of active channels with partial radiation patterns obtained from the independent excitation of each channel. The antenna gains measured in Ka/K/Ku band of the antenna system were more than 39.6 dBi, 37.5 dBi, 29.6 dBi, respectively. And, the antenna system showed good system performances such as Ka_Tx EIRP more than 43.7 dBW and K/Ku_Rx G/T more than 13.2 dB/K and 7.12 dB/K, respectively.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.1
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• pp.29-37
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• 1999

In this study, we have prepared PLT thin films having various La concentrations by using sol-gel method and studied on the effect of La concentration on the electrical properties of PLT thin films. As the La concentration increases from 5mol% to 28mol%, the dielectric constant at 10kHz increases from 428 to 761, while the loss tangent decreases from 0.063 to 0.024. Also, the leakage current density at 150kV/cm has a tendency to decrease from 6.96${\mu}A/cm^2$ to 0.79${\mu}A/cm^2$. In the result of hysteresis loops of PLT thin films, the remanent polariation and the coercive field decrease from 9.55${\mu}C/cm^2$ to 1.10${\mu}C/cm^2$ and from 46.4kV/cm to 13.7kV/cm, respectively. With the result of the fatigue test on the PLT thin films, we have found that the fatigue properties are improved remarkably as the La concentration increases from 5 mol% to 28mol%. In particular, the PLT28) has paraelectric phase and its charge storage clensity and leakage current density at 5V are 134fC/${\mu}cm^2$ and 1.01${\mu}A/cm^2$, respectively. The remanent polarization and coercive field of the PLT(10) film are 6.96${\mu}C/cm^2$ and 40.2kV/cm, respectively. After applying of $10^9$ square pulses with ${\pm}5V$, the remanent polarilzation of the PLT(10) film decreases about 20% from the initial state. In the results, we conclude that the 10mol% and the 28mol% La doped PLT thin films are very suitable for the capacitor dielectrics of new generation of DRAM and NVFRAM respecitively.