• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.3
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• pp.242-248
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• 2008

The structural, optical and electrical properties of ZnO films doped with 1.5 at% of 3A materials(B, Al, Ga, In) were studied by sol-gel process. The films were found to be c-axis (002) oriented hexagonal structure on glass substrate, when post heated at 500 $^{\circ}C$. The surface of the films showed a uniform and nano size microstructure and the crystalline size of doped films decreased. The lattice constants of ZnO:B/Al/Ga increased than that of ZnO, while ZnO:In decreased. All the films were highly transparent(above 90 %) in the visible region. The energy gaps of ZnO:B/Al/Ga were increased a little, but that of ZnO:In was not changed. The resistivities of ZnO:Al/Ga/In were less than 0.1 $\Omega$cm. All the films showed a semiconductor properties in the light or temperature, however ZnO:In was less sensitive to it. A figure of merit of ZnO:In had the highest value of 0.025 $\Omega^{-1}$ in all samples.

• Journal of the Korean Society of Safety
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• v.28 no.4
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• pp.66-71
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• 2013

There is a critically structural problem of scaffolding system when one of scaffold columns is remove to be used as a gangway for their temporary office in the structure before finishing all such as an apartment or office building. This is not used to checking to structurally checking at a construction site. This study is to find out which system at a site will be more effective and low-cost-high effectiveness of aluminum ladder, timber ladder, ${\phi}$1/2 inch steel pipe truss with a type of concave, convex warren truss ladders. Theses are structurally tested with horizontal set as a truss type with 1.8 meter long. Concentrated load has been loaded at the upper center of the system and checked its strain at the bottom center, using aluminum-use strain gage and steel-use gauge have been attached concave warren truss with diameter 1/2 inch has 14% stronger than convex truss. Convex truss has almost same strength as an aluminum ladder truss, it is found out.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.2 s.245
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• pp.194-201
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• 2006

Gait analysis is essential to identify accurate cause and knee condition from patients who display abnormal walking. Traditional linear tools can, however, mask the true structure of motor variability, since biomechanical data from a few strides during the gait have limitation to understanding the system. Therefore, it is necessary to propose a more precise dynamic method. The chaos analysis, a nonlinear technique, focuses on understand how variations in the gait pattern change over time. Eight healthy eight subjects walked on a treadmill for 100 seconds at 60 Hz. Three dimensional walking kinematic data were obtained using two cameras and KWON3D motion analyzer. The largest Lyapunov exponent from the measured knee angular displacement time series was calculated to quantify local stability. This study quantified the variability present in time series generated from gait parameter via chaos analysis. Knee flexion-extension patterns were found to be chaotic. The proposed Lyapunov exponent can be used in rehabilitation and diagnosis of recoverable patients.

• Journal of the Korean Institute of Intelligent Systems
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• v.20 no.1
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• pp.146-152
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• 2010

In this paper, we implemented the intelligent healthcare system self-diagnosis that can achieve self-diagnosis by measured bio-signal(blood pressure, blood sugar, body fat monitor) after the recognize a user to access using RFID. The implemented healthcare self-diagnosis intelligent system is consist of kiosk structure that is RFID reader, bio-signal measuring instrument(hemadynamometer, glucometer, body fat monitor), computer for a part of database server and printer for print the result of self-diagnosis. It can achieve self-diagnosis of a user after compare and analyze the measured data and information of a user from database. The implemented system can make simple self-diagnosis even if not take a physical examination at hospital and apply to company, school, etc.

• Journal of Navigation and Port Research
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• v.33 no.6
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• pp.429-436
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• 2009

Container cranes are main equipments to load and unload containers to container ships at container terminals. If a crane breakdowns, it can reduce the productivity of container terminals. This paper deals with Preventive Maintenance (PM) schedules for the container cranes. The cranes consist of many parts and we analyze the structure of a container crane using the tree models. Next, we apply a Genetic Algorithm (GA) for determining optimal PM schedule and evaluate the performance of the proposed method through simulation system Finally, we explain how to adjust the PM schedule found in industry based on work schedules.

• 한국전산유체공학회:학술대회논문집
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• 2007.04a
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• pp.87-90
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• 2007

A general purpose program NUFLEX for the analysis 3-D thermo/fluid flow and pre/post processor in complex geometry has been developed, which consists of a flow solver based on FVM and GUI based pre/post processor. The solver employs a general non-orthogonal grid system with structured grid and solves laminar and turbulent flows with standard/RNG ${\kappa}-{\varepsilon}\;SST$ turbulence model. In addition, NUFLEX is incorporated with various physical models, such as interfacial tracking, cavitation, MHD, melting/solidification and spray model. For the purpose of verification of the program and testing the applicability, many actual problems are solved and compared with the available data. Comparison of the results with that by STAR-CD or FLUENT program has been also made for the same flow configuration and grid structure to test the validity of NUFLEX.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2017.05a
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• pp.244-245
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• 2017

This study aims to develop high durability graphene / epoxy paint for durability improvement of construction structure. For the development of graphene / epoxy coatings, first, graphene must remain stable in the polymer. Second, the integrity of graphene and polymer should be ensured. Accordingly, in order to obtain dispersibility, surface modification of graphene nanoplate(GnP) with CH and COOH functional groups and its dispersibility in organic solvents were investigated. Also, Fourier Transform Infrared Spectroscopy(FT-IR) analysis and Atomic Force Microscope(AFM) analysis were performed to confirm whether the functional groups were synthesized by surface modification. As a result, FT-IR and AFM analysis did not confirm the surface modification, but GnP was found to be stable when dispersed in an organic solvent.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.48 no.1
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• pp.39-44
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• 1999

The dielectric layers in AC plasma display panel(PDP) are essential to the discharge cell structure, because they protect metal electrodes from sputtering by positive ion bombarding in discharge plasma and form a sheath of wall charges which are essential to memory function of AC PDP. This layer should have high dielectric breakdown voltage, and also be transparent because the luminance of PDP is strongly correlated this layer. In this paper, we discussed the dielectric breakdown voltage and transparency of the dielectric layer under various conditions. As a result, on the $15\mum$ thickness, the minimum dielectric breakdown voltage was 435V and the transmission coefficient was about 80% after $570^{\circ}C$ firing process. It can be proposed that the resonable dielectric thickness in AC PDP is $15\mum$ because it has about 75V margin on the maximum applied voltage.

• Proceedings of the KIEE Conference
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• 1999.11d
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• pp.860-862
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• 1999

we have grown vertically aligned carbon nanotubes on a large area of Co-Ni codeposited Si substrates by thermal chemical vapor deposition using $C_{2}H_{2}$ gas. The carbon nanotubes grown by the thermal chemical vapor deposition are multi-wall structure, and the wall solace of nanotubes is covered with defective carbons or carbonaceous particles. The carbon nanotubes range from 50 to 120nm in diameter and about $130{\mu}m$ in length at $950^{\circ}C$. The turn-on voltage was about $0.8V/{\mu}m$ with a current density of $0.1{\mu}A/cm^2$ and emission current reveals the Fowler-Nordheim mode.

• Proceedings of the KIEE Conference
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• 1999.11d
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• pp.909-911
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• 1999

Metalization technology of the fine patterns by electroless plating is required in place of electrodeposition as high-density printed circuit boards (PCB) become indispensable with the miniaturization of electronic components. Electroless nickel plating is a suitable diffusion barrier between conductor metals, such as Al and Cu, and solder is essetional in electronic packaging in order to sustain a long period of service. Moreover, Electroless nickel has particular characteristics including non-magnetic property, amorphous structure, wear resistance, corrosion protection and thermal stability. In this study fundamental aspects of electroless nickel deposition were studied with effect of complexeing agents of different kinds. Then, the property of electroless deposit are controlled by the composition of the deposition solution, the deposition condition such as temperature and pH value and so on. the characteristics of the deposits has been carried out.