• Journal of the Korean Institute of Gas
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• v.27 no.1
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• pp.78-85
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• 2023

Fixed-bed reactor Computational Fluid Dynamics (CFD) simulation of methanol steam reforming reaction was performed using the intrinsic kinetic data of the copper-impregnated hydrotalcite catalyst. The activation energy of the copper hydrotalcite catalyst obtained from the previous study results was 97.4 kJ/mol, and the pre-exponential was 5.904 × 10¹⁰. Process simulation was performed using the calculated values and showed a similar tendency to the experimental results. And the conversion rate according to the change of the reaction temperature (200 - 450 ℃) and the molar ratio of methanol and water was observed using the intrinsic kinetic data. In addition, mass and heat transfer phenomena analysis of a commercial reactor (I.D. 0.05 - 0.1m, Length 1m) was predicted through axial 2D Symmetry simulation using the power law model of the above kinetic constants.

• Journal of the Korea Society of Computer and Information
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• v.26 no.1
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• pp.103-110
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• 2021

In this paper, we compare two access control mechanisms for D2D(Device-to-Device) systems in 5G wireless networks and propose an effective access control for 5G D2D networks. Currently, there is no specified access control for 5G D2D networks but there can be two access control approaches for 5G D2D networks. One is the UE-to-Network Relay based access control and the other is the Remote UE(User Equipment) based access control. The former is a UE-to-Network Relay carries out the access control check for 5G D2D networks but the latter is a Remote UE performs the access control check for 5G D2D networks. Through simulation and evaluation, we finally propose the Remote UE based access control for D2D systems in 5G wireless networks. The proposed approach minimizes signalling overhead between the UE-to-Network Relay and the Remote UE and more efficiently performs the access control check, when the access control functionalities are different from the UE-to-Network Relay in 5G D2D networks.

• The KIPS Transactions:PartD
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• v.12D no.5 s.101
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• pp.797-806
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• 2005

The objective of the In-h(High Level Architecture) have recommended by DoD(Department of Defense) is to facilitate interoperability among simulations and to promote reuse of their components. There are many legacy simulation softwares developed before the HLA becomes simulation standard. The integration of legacy simulations into federations using the HLA is an important research topic in M&S(Modeling and Simulation) area. Legacy simulation softwares of the mission critical industry such as nuclear and aerospace are generally use Fortran language. However, the reuse of those is not easy because the HLA is not support Fortran language. This paper suggests a integration method which minimizes the modification of legacy simulation software and migrates the legacy simulation software to HLA federation. Each federate participating in federation have the separated executables that communicate via a shared memory created at run-time. Two types of shared memory blocks are used for publication and subscription. Declaration block for global variables used in legacy simulation software is separated for publication and subscription and then mapped as classes of objects and interactions for the HLA FOM design. To validate the suggested method, we approached the HLA integration of legacy nuclear simulation code being used in plant design and to observe the integration results, we used the FMT(Federation Management Tool). The diagnostic information which the FTM displays showed that our method can be successfully and effectively used for a HLA federation.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.10
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• pp.51-56
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• 2004

We propose and fabricate an 1${\times}$2 asymmetric optical switch by TOE using SOI wafer based on silicon which has very large TOE figure and it is a good material for optical devices. SOI wafer consists of 3 layers; upper Si layer for device(waveguide;core, n=3.5), buried oxide layer for insulator(clad, n=1.5) and Si substrate layer. We designed 1${\times}$2 asymmetric y-branched single mode optical waveguide switch by BPM simulation and metal heater by heat transfer simulation. Fabricated switch shows about 3.5 watts of power consumption and over 20dB of crosstalk between output channels.

• The Korean Journal of Ceramics
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• v.5 no.1
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• pp.40-43
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• 1999

In order to investigate Sn substitution sites and interstitial O atoms in tin-doped indium oxide, molecular dynamics (MD) simulations were carried out. There are two kinds of cation sites in $In_2O_3$, namely b-site and d-site. NTP-MD simulations under the condition of 300 K and 0 GPa were performed with two kinds of cells substituted by Sn atoms at each site. The excess oxygen atom accompanied with Sn doping was also taken into consideration. According to the calculations of Sn potential energies in each site, it was revealed that Sn atoms were substituted for b-sites rather than for d-sites. It was also revealed that the interstitial excess oxygen atoms tend to be connected with the Sn atoms substituted for the d-sites Sn rather than for the b-site. There MD simulation results well agreed with the experimental results.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.919-922
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• 2008

The objective of this study is to design the full-scale fire test facility of the railroad vehicle with CFD simulation. In the results, the step expansion system should be good enough for the measuring system. Uniform flow is achieved at eight-to-ten diameters of the expanded duct behind the step for moderate expansion ratios($D_{orifice}/D_{duct}$ = 2 being a good choice). To optimization of the fire products collector system with 5 dampers, the additional CFD simulation was also carried out. These results will be help for the railroad fire safety research.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.1A
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• pp.107-112
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• 2004

We propose the optimum TO-can package design in SFF/SFP optical transceiver modules to improve 3dB-bandwidth. The frequency response of TO-38 package is measured and compared to simulation where the 3dB-bandwidth was 3.5GHz. For a higher operating bandwidth (>15GHz), the new optimized physical geometries of TO-can package such as bonding-wire, lead and material was suggested. The optimal result of simulation shows that TO-can package can be used at a higher bit rate optical module of 10Gbps.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1623-1624
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• 2006

It is a paper for design, manufacture and estimation of industry inkjet head. Simulations for Actuator, Ink flow and Ejection are executed for securing design ability. Relations between droplet and properties of ink are explained closely through simulation for nozzle. Actually, two silicon plates are made by dry and wet etching and directly bonded. PZT materials is attached on the bended ink flow part and cut to $540{\mu}m$ interval by dicing saw. Actuator was seen variation within 10% between simulation and actual head. Through the ejection estimation, it is shown that stabilized driving voltages change according to viscosity and surface tension of metal ink. Using the metal ink of viscosity of 4.8 cps and surface tension of 0.025 N/m, it is possible to eject the stable droplets with 5m/s, 20 pl, 5 kHz.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.7
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• pp.653-659
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• 2016

This paper proposes an ultra-wideband Log-Periodic Dipole Array(LPDA) antenna for the feeder of a reflector antenna to be used for airborne spinning direction-finding and detecting wideband signals. To obtain the ultra-wideband characteristics over the 20:1 bandwidth from S to Ka band, the radiation elements of the antenna were printed on a substrate and a wedge-typed dielectric supporter with robust structure was inserted between the substrates. Also, the center portion of the supporter was replaced by a styrofoam material to reduce the supporter weight. The 5-dB return loss of the designed LPDA antenna showed ultra-wideband characteristics, which are 37.57:1(1.09~40.95 GHz) in the simulation and 33.85:1(1.31~44.35 GHz) in the measurement. We achieved the required gains of 5.78 dBi in the simulation and 5.76 dBi in the measurement in the operating band. The proposed robust, light-weight, and ultra-wideband LPDA antenna confirmed that it can be applied for airborne applications.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.4
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• pp.611-619
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• 2008

2.5D Mapping system that embody in this paper can make new design by doing draping to live various texture and model picture image of fashion clothes by pattern, and can confirm clothes work to simulation without producing direction sample or product directly. Also, the system can support function that can forecast fabric design and state of end article exactly, and the system can bring competitive power elevation of fashion industry and cost-cutting effect by doing draping using database of fabric and model picture image. 2.5D Mapping system composed and embodied by mesh warp algorithm module, light and shade extraction and application module, mapping path extraction module, mesh creation and transformation module, and 2.5D mapping module for more natural draping. Future work plans to study 3D fashion design system that graft together 3D clothes technology and 3D human body embodiment technology to do based on embodiment technology of 2.5D mapping system and overcomes expression limit of 2.5D mapping technology.