• Korean Journal of Remote Sensing
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• v.39 no.5_3
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• pp.1061-1067
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• 2023

In this letter, we simulated an atmospheric correction for Sentinel-2 images, of which spectral bands are similar to Compact Advanced Satellite 500-4 (CAS500-4). Using the second simulation of the satellite signal in the solar spectrum - vector (6SV)2.1 radiation transfer model and random forest (RF), a type of machine learning, we developed an RF-based atmospheric correction model to simulate 6SV2.1. As a result, the similarity between the reflectance calculated by 6SV2.1 and the reflectance predicted by the RF model was very high.

• Journal of the Korea Society of Computer and Information
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• v.29 no.8
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• pp.157-164
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• 2024

In this paper, we propose a discussion that the feasibility of deploying a deep learning-based detector on the resource-limited board. Although many studies evaluate the detector on machines with high-performed GPUs, evaluation on the board with limited computation resources is still insufficient. Therefore, in this work, we implement the deep-learning detectors and deploy them on the compact board by parsing and optimizing a detector. To figure out the performance of deep learning based detectors on limited resources, we monitor the performance of several detectors with different H/W resource. On COCO detection datasets, we compare and analyze the evaluation results of detection model in On-Board and the detection model in On-GPU in terms of several metrics with mAP, power consumption, and execution speed (FPS). To demonstrate the effect of applying our detector for the military area, we evaluate them on our dataset consisting of thermal images considering the flight battle scenarios. As a results, we investigate the strength of deep learning-based on-board detector, and show that deep learning-based vision models can contribute in the flight battle scenarios.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.4
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• pp.425-430
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• 2012

In this study, a preconverter of an MCFC for an emergency electric power supplier is numerically simulated to increase the hydrogen production from natural gas (methane). A commercial code is used to simulate a porous catalyst with a user subroutine to model three dominant chemical reactions-steam reforming, water-gas shift, and direct steam reforming. To achieve a fuel conversion rate of 10% in the preconverter, the required external heat flux is supplied from the outer wall of the preconverter. The calculated results show that the temperature distribution and chemical reaction are extremely nonuniform near the wall of the preconverter. These phenomena can be explained by the low heat conductivity of the porous catalyst and the endothermic reforming reaction. The calculated results indicate that the use of a compact-size preconverter makes the chemical reaction more uniform and provides many advantages for catalyst maintenance.

• Journal of Digital Convergence
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• v.11 no.12
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• pp.479-485
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• 2013

Virtualization is a promising approach to consolidating multiple online services onto a smaller number of computing resources. A virtualized server environment allows computing resources to be shared among multiple performance isolated platforms called virtual machines. Through server virtualization software, applications servers are encapsulated into VMs, and deployed with APIs on top generalized pools of CPU and memory resources. Networking and security have been moved to a software abstraction layer that transformed computing, network virtualization. And it paves the way for enterprise to rapidly deploy networking and security for any application by creating the virtual network. Stochastic reward net (SRN) is an extension of stochastic Petri nets which provides compact modeling facilities for system analysis. In this paper, we develop SRN model of network virtualization based on virtual switch. Measures of interest such as switching delay and throughput are considered. These measures are expressed in terms of the expected values of reward rate functions for SRNs. Numerical results are obtained according to the virtual switch capacity and number of active VMs.

• Journal of the Microelectronics and Packaging Society
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• v.24 no.4
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• pp.19-22
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• 2017

In this study, wavelength-free $1{\times}N$ optical splitter using a tapered polymer waveguide was studied to realize the transmission network of high-speed information communication network. Based on the evaluation of mode converting characteristics of splitter having two tapered multi-mode interference structures, an optimized structure of the $1{\times}N$ splitter was proposed for wide-range of input wavelength. 2D-BPM analysis $1{\times}8$ model showed that insertion loss of the proposed splitter is less than 10 dB for wavelength of input source from 1260 nm to 1650 nm.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.30 no.2
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• pp.71-77
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• 2016

The dielectric barrier discharge (DBD) has low efficiency due to about 70% input power is consumed as thermal energy in the discharge space. However, because of the usage of DBD ozone generator is easier than other methods. The DBD ozone generator has been widely applied for high concentration ozone generation in the industrial application. But, the low-capacity compact DBD ozone generator is not applied so far. Therefore, the DBD ozone generator is necessary to improve ozone production efficiency and reduce the capacity. In this paper, the stainless steel pipe inner electrode was designed with hall type and screw type to improve the ozone production yield. The manufactured two inner electrodes were experimented with normal type for comparison of the discharge characteristics and the ozone generating characteristics. As the experimental results, the discharge current effective value of designed inner electrodes with hall type and screw type are higher than the normal type, due to unequal electric field is formed at the boundary. However, the difference of designed and original electrodes is less than 0.1mA that has no effect on the discharge characteristic. On the other hand, the screw type inner electrode increased higher than original model about 7 times when the flow rate of the oxygen source gas was increased from $0.6{\ell}/min$ to $1.0{\ell}/min$ The reason was assumed by the flow rate of the raw gas through the inner electrode was became fast that has a cooling effect. The designed hall type and screw type inner electrodes have shown good performances in ozone generation and ozone production that better than normal type in the same electrode surface area.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.76.1-76.1
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• 2015

Optical resonances of metallic or dielectric nanoantennas enable to effectively convert free-propagating electromagnetic waves to localized electromagnetic fields and vice versa. Plasmonic resonances of metal nanoantennas extremely modify the local density of optical states beyond the optical diffraction limit and thus facilitate highly-efficient light-emitting, nonlinear signal conversion, photovoltaics, and optical trapping. The leaky-mode resonances, or termed Mie resonances, allow dielectric nanoantennas to have a compact size even less than the wavelength scale. The dielectric nanoantennas exhibiting low optical losses and supporting both electric and magnetic resonances provide an alternative to their metallic counterparts. To extend the utility of metal and dielectric nanoantennas in further applications, e.g. metasurfaces and metamaterials, it is required to understand and engineer their scattering characteristics. At first, we characterize resonant plasmonic antenna radiations of a single-crystalline Ag nanowire over a wide spectral range from visible to near infrared regions. Dark-field optical microscope and direct far-field scanning measurements successfully identify the FP resonances and mode matching conditions of the antenna radiation, and reveal the mutual relation between the SPP dispersion and the far-field antenna radiation. Secondly, we perform a systematical study on resonant scattering properties of high-refractive-index dielectric nanoantennas. In this research, we examined Si nanoblock and electron-beam induced deposition (EBID) carbonaceous nanorod structures. Scattering spectra of the transverse-electric (TE) and transverse-magnetic (TM) leaky-mode resonances are measured by dark-field microscope spectroscopy. The leaky-mode resonances result a large scattering cross section approaching the theoretical single-channel scattering limit, and their wide tuning ranges enable vivid structural color generation over the full visible spectrum range from blue to green, yellow, and red. In particular, the lowest-order TM01 mode overcomes the diffraction limit. The finite-difference time-domain method and modal dispersion model successfully reproduce the experimental results.

• Journal of Ocean Engineering and Technology
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• v.23 no.2
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• pp.69-73
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• 2009

The objective of this study was to obtain a better understanding of the delayed hydride cracking (DHC) of Zr-2.5Nb alloy. The DHC model has some defects: first, it cannot explain why the DHC velocity (DHCV) becomes constant regardless of an applied stress intensity factor, even though the stress gradient is affected by the applied stress intensity factor at the notch tip. Second, it cannot explain why the DHCV has a strong dependence on the method of approaching the test temperature by a cool-down or a heating-up, even under the same stress gradient, and third, it cannot predict any hydride size effect on the DHC velocity. The DHC tests were conducted on Zr-2.5Nb compact tension specimens with the test temperatures reached by a heating-up method and a cool-down method. Crack velocities were measured in hydrided specimens, which were cooled from solution-treatment temperatures at different rates by being furnace-cooled, water-quenched, and liquid nitrogen-quenched. The resulting hydride size, morphology, and distributions were examined by optical metallography. It was found that fast cooling rates, which produce very finely dispersed hydrides, result in higher crack growth rates. This different DHC behavior of the Zr-2.5Nb tube with the cooling rate after a homogenization treatment is due to the precipitation of the $\gamma$-hydrides only in the water-quenched Zr-2.5Nb tube. This experiment will provide supporting evidence that the terminal solid solubility of a dissolution (TSSD) of $\gamma$-hydrides is higher than that of $\delta$-hydrides.

• Journal of the Korean Institute of Intelligent Systems
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• v.25 no.3
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• pp.248-253
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• 2015

In order to adapt to human's life and perform missions, a humanoid robot needs a height at least similar with children's. In this paper, we proposed a humanoid robot which is like a child who is taller than 1m. We presented showing the humanoid robot's kinematics, designing of a three-dimensional model, developing mechanisms, and the hardware structures using servo motors and compact size PC. Through this process, we designed and manufactured child humanoid robot 'CHARLES(Cognitive Humanoid Autonomous Robot with Learning and Evolutionary Systems)' that is robot is 1m 10cm tall and 8.16kg in weight. For robot's walking, we applied to ZMP-based walking technique and the creation algorithm is applied for walking patterns. Through experiments, we analyzed walking patterns according to the creation and changing parameter values.

• Archives of design research
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• v.16 no.3
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• pp.183-190
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• 2003

It is a fundamental pre-requisite to thoroughly analyse and understand the things which are being designed in the process of industrial design. However, it is not always easy to acquire appropriate data to meet all the requirements to finally design a functionally superior products. This paper proposes an industrial design model with heightened reliability using the orthogonal array tables, which are fairly handy to apply when there are many design criteria to be considered at the onset stage Especially, in this research, the basic purpose of the orthogonal arrays that they try to compact the range of experiments and to improve the effectiveness of the experiment results is answered under average industrial design processes. At the same time, non-quantitative data of design factors are quantitative by the concurrency in design and their mutual actions are examined. This method can help industrial designers in narrowing their design possiblities by depicting more valid data, thus producing quality product designs by deriving optimal control factors.