• Electronics and Telecommunications Trends
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• v.38 no.1
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• pp.36-45
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• 2023

The increasing demand for ultra-high efficiency of compact power conversion systems for electric vehicle applications has brought GaN power semiconductors to the fore due to their low conduction losses and fast switching speed. In particular, the development of materials and core device processes contributed to remarkable results regarding the publication of vertical GaN power devices with high breakdown voltage. This paper reviews recent advances on GaN material technology and vertical GaN power device technology. The GaN material technology covers the latest technological trends and GaN epitaxial growth technology, while the vertical GaN power device technology examines diodes, Trench FETs, JFETs, and FinFETs and reviews the vertical GaN PiN diode technology developed by ETRI.

• Korean Journal of Soil Science and Fertilizer
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• v.46 no.4
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• pp.237-244
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• 2013

Radar remote sensing is appropriate for monitoring rice because the areas where this crop is cultivated are often cloudy and rainy. Especially, Synthetic Aperture Radar (SAR) can acquire remote sensing information with a high temporal resolution in tropical and subtropical regions due to its all-weather capability. This paper analyzes the relationships between backscattering coefficients of rice measured by RADARSAT-2 SAR and growth parameters during a rice growth period. We examined the temporal variations of backscattering coefficients with full polarization. Backscattering coefficients for all polarizations increased until Day Of Year (DOY 222) and then decreased along with Leaf Area Index (LAI), fresh weight, and Vegetation Water Content (VWC). Vertical transmit and Vertical receive polarization (VV)-polarization backscattering coefficients were higher than Horizontal transmit and Horizontal receive polarization (HH)-polarization backscattering coefficients in early rice growth stage and HH-polarization backscattering coefficients were higher than VV-polarization backscattering coefficients after effective tillering stage (DOY 186). Correlation analysis between backscattering coefficients and rice growth parameters revealed that HH-polarization was highly correlated with LAI, fresh weight, and VWC. Based on the observed relationships between backscattering coefficients and variables of cultivation, prediction equations were developed using the HH-polarization backscattering coefficients.

• Journal of the Korean institute of surface engineering
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• v.50 no.1
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• pp.10-16
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• 2017

This article reports for the first time on the lateral growth of PEO (plasma electrolytic oxidation) films on Al1050 alloy by the application of anodic pulse current in an alkaline electrolyte. Generation of microarcs was observed at the edges initially and then moved towards the central region with PEO treatment time. Disc type PEO film islands with about $20{\mu}m$ diameter were formed first and they grew laterally by the formation of new disc type PEO films at the edge of pre-formed PEO islands. The PEO film islands were found to be interconnected completely and form a continuous PEO film when generation of small size microarcs are terminated at the central part of the specimen, resulting in very smooth surface with low surface roughness less than $1{\mu}m$ of $R_a$. Further PEO treatment after the complete interconnection of PEO films islands showed local thickening of PEO films by vertical growth. It is concluded that very smooth PEO film surface can be obtained by lateral growth mechanism rather than vertical growth of them.

• International Journal of Advanced Culture Technology
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• v.9 no.1
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• pp.129-135
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• 2021

In this study, we built a mock-up of an indoor garden for private use and vertical gardens were installed on the walls of this indoor garden model. The purpose of this study is to examine the types of plants for best fit for growth and nurture in vertical garden and to identify the effects of indoor air quality improvement by these plants. As the result of the experiment, 22 species out of 32 species previously used for indoor garden was selected to be suitable for vertical gardens of a personal indoor garden. 10 species were found to be inappropriate for a personal indoor garden in terms of ornamental value, growth status and maintenance. The effect of plants on reducing CO2 has been proven by many studies. Also, through photosynthesis, plants combine CO2 with water and produce sugars and O2 (oxygen). Everyone accepts this fact. In nature, the production of oxygen is so important that without plants we would soon use it up and die. From the NASA Fact Sheet we know that air contains 20.95% O2 and 0.04% CO2. If you had enough plants in a room to use up all of the all of CO2 and convert it to oxygen, the oxygen levels would increase from 20.95% to 21%. This increase is difficult to detect and would have no effect on humans.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.6
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• pp.535-541
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• 1999

Low-dislocation-density large-diameter GaAs single crystals with low-residual-strain have been strongly required. We have developed dislocation-free 3-inch Si doped GaAs crystals for photonic devices, and low-dislocation-density low-residual-strain 4-inch to 6-inch semi-insulating GaAs crystals for electronic devices by Vertical Bridgman(VB) technique. We confirmed that VB substrates with low-residual-strain have higher resistance against slip-line generation during MBE process. VB-GaAs single crystals show uniform radial profile of resistivity reflecting to the flat solid-liquid interface during the crystal growth. Uniformity of micro-resistivity of VB-GaAs substrate is much better than of the LEC-GaAs substrate, which is due to the low-dislocation-density of VB-GaAs single crystals.

• Journal of the Korean Institute of Navigation
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• v.14 no.2
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• pp.77-82
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• 1990

In this paper the results for thin multi-layer InGaAsP($1.3{\mu}m$)/InP crystal growth by vertical liquid epitaxial growing furnance have been presented. The growth rates of InGaAsP layer and InP layer at cooling rate of $0.3^{\circ}C$/min and the growing temperature of $630^{\circ}C$ were obtained as $0.11 {\mu}m$/min and $0.06 {\mu}m$/min, respectively, by the uniform cooling with two phase solution technique.

• Proceedings of the Korea Association of Crystal Growth Conference
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• 1999.06a
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• pp.129-157
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• 1999

Low-dislocation-density large-diameter GaAs single crystals with low-residual-strain have been strongly required. We have developed dislocation-free 3-inch Si-doped GaAs crystals for photonic devices [1], and low-dislocation-density low-residual-strain 4-inch to 6-inch [2, 3] semi-insulating GaAs crystals for electronic devices by Vertical Boat (VB) technique. We confirmed that VB substrates with low-residual-strain have higher resistance against slip-line generation during MBE process. VB-GaAs single crystals show uniform radial profile of resistivity reflecting to the flat solid-liquid interface during the crystal growth. Uniformity of micro-resistivity of VB-GaAs substrate is much better than that of the LEC-GaAs substrate, which is due to the low-dislocation-density of VB-GaAs single crystals.

• Journal of the korean academy of Pediatric Dentistry
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• v.46 no.2
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• pp.173-182
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• 2019

Vertical facial growth triggers the rotation of mandible to move the chin point to the downward and backward direction, which showed remarkably effective result making the less prominent chin. Recently, the intraoral removable appliance utilizing class III elastic demonstrated the vertical growth trigger mechanism. The treatment change was very fast and wearing was quite easy, compared to extraoral appliances. The purpose of this study was to verify the duration of the treatment on class III malocclusion using intraoral removable appliances, which designed to accelerate vertical facial growth. 56 patients were selected with the complaint of the protruded mandible and class III malocclusion (overjet : -3 - 0 mm, overbite : 0 - 4 mm). Information like; age at start, duration of the treatment events, type of the treatment, overjet, overbite etc. was collected and calculated. The average age of the patients delivering the initial brace was $8.75{\pm}1.10year$. Most of the anterior crossbite was resolved within 6 months. The total treatment period was $21.79{\pm}10.73months$ with the additional procedures like the alignment of anterior teeth and torque control using additional removable and fixed orthodontic appliances. The correlation study showed that patient's cooperation (p = 0.000) and the use of fixed appliance (p = 0.032) were significantly influenced on treatment duration.

• Korean Journal of Soil Science and Fertilizer
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• v.47 no.2
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• pp.85-91
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• 2014

Ground-based polarimetric scatterometers have been effective tools to monitor the growth of crop with multi-polarization and frequencies and various incident angles. An important advantage of these systems that can be exploited is temporal observation of a specific crop target. Polarimetric backscatter data at L-, C- and X-bands were acquired every 10 minutes. We analyzed the relationships between L-, C- and X-band signatures, biophysical measurements over the whole corn growth period. The Vertical transmit and Vertical receive polarization (VV) backscattering coefficients for all bands were greater than those of the Horizontal transmit and Horizontal receive polarization (HH) until early-July, and then thereafter HH-polarization was greater than VV-polarization or Horizontal transmit and Vertical receive polarization (HV) until the harvesting stage (Day Of Year, DOY 240). The results of correlation analysis between the backscattering coefficients for all bands and corn growth data showed that L-band HH-polarization (L-HH) was the most suited for monitoring the fresh weight ($r=0.95^{***}$), dry weight ($r=0.95^{***}$), leaf area index ($r=0.86^{**}$), and vegetation water content ($r=0.93^{***}$). Retrieval equations were developed for estimating corn growth parameters using L-HH. The results indicated that L-HH could be used for estimating the vegetation biophysical parameters considered here with high accuracy. Those results can be useful in determining frequency and polarization of satellite Synthetic Aperture Radar stem and in designing a future ground-based microwave system for a long-term monitoring of corn.

• Journal of Information Display
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• v.2 no.3
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• pp.54-59
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• 2001

The role of $NH_3$ for vertical alignment of CNTs was investigated. The direct cause of the alignment was a dense distribution of catalytic metal particles, but which was kept catalytically active during the growth process by $NH_3$. This allows a dense nucleation of the CNTs, and consequently, assists vertical alignment through entanglement and mechanical leaning among the tubes. The CNTs grow in a base growth mode. Several evidences were presented including a direct cross-sectional TEM observation. Since Ni is consumed both by silicide reaction and by capture in the growing tube, the growth stops when Ni is completely depleted. This occurs faster for smaller particles, and thus a longer growth results in thin bottom with poor adhesion.