• 한국전산유체공학회:학술대회논문집
• /
• 1996.05a
• /
• pp.125-130
• /
• 1996

A numerical analysis is conducted on heat transfer and fluid flow of a plasma spraying process under the DC-RE hybrid electromagnetic field. Plasma flow is analyzed by using Eulerian approach and the equation of particle motion is simultaneously solved using a trajectory analysis with a lumped-heat-capacity model. Axisymmetric two dimensional electromagnetic fields governed by Maxwell's equations are solved based on a vector potential concept. The effects of the RF electromagnetic field on the temperature and velocity fields of the turbulent plasma flow are clarified. Control characteristics of phase changes and dispersed features of particles by applying the RF electromagnetic field are also clarified in an attempt to improve the plasma spraying process

• Proceedings of the KSME Conference
• /
• 2008.11a
• /
• pp.1784-1787
• /
• 2008

Molecular dynamics (MD) simulations are used to analyze behavior of copper nanowires under cyclic loading. The embedded atom method (EAM) potential is employed to represent atomic interaction. Cyclic load is applied in two ways (Forward Tension / Reverse Compression and Forward Compression / Reverse Tension). The results show that dislocations are piled up as a result of plastic deformation during alternate tensile and compressive loading. After cyclic loading with a change of direction, yield stress decreases in consequence of the effect by the dislocation pileups. On the other hand, under FC/RT cyclic load, phase transformation represent associated with mechanical twinning. And copper nanowire can return to almost former undeformed condition during tensile loading at 300K.

• Journal of Distribution Science
• /
• v.12 no.3
• /
• pp.25-32
• /
• 2014

Purpose - This study reviews changes in the steel export-import structure between Korea and Japan using a trade related index; it focuses on analyzing comparative advantage based on time-series analysis statistics data using the trade intensity index (TII), revealed comparative advantage index (RCA), and trade specialization index (TSI). Research design, data, and methodology - In terms of their economic phase, Korea and Japan have a mutually complementary character. Therefore, this study aims to understand each country's trade structure to strengthen Korea-Japan economic cooperation, examine trade drawbacks, analyze factors that affect trade, and identify ways to improve and expand trade. Results - The results indicate immense potential for mutual cooperation and complementariness, which will yield guaranteed adequate profits comparable to those of any regional economic integrated community. Conclusion - From our viewpoint, Northeast economic cooperation can facilitate industry technological cooperation with Japanese partners in the prevailing environment that is characterized by increasing competition among industries and the need to secure stable resource supplies as well as the expansion of the export market and diversification, which can have significant positive implications.

• Architectural research
• /
• v.15 no.3
• /
• pp.143-150
• /
• 2013

The Korean government recently has rediscovered the potential value of Han-Ok, the Korean traditional house, as an eco-friendly building. In order to objectively verify the environmental performance of Han-Ok as a low carbon green building, this paper suggests the analysis method of GHG emission load of Korean traditional house, based on Life Cycle Assessment, which is commonly abbreviated to "LCA". The environmental impacts caused by building construction and operation can be analyzed through the sum of input and output data from every phase. The study particularly describes the GHG reduction effect by using traditional building materials such as wood products, traditional clay roof tiles, and mud, which are mainly used to construct Han-Ok. Also the study proposes the method for comparative analysis of quantity of GHG emissions in building's entire life cycle so that the data can be used as a reliable basis to optimize the environmental performance of building.

• Proceedings of the KIPE Conference
• /
• 2002.07a
• /
• pp.466-469
• /
• 2002

Many power plants in the thermal and hydraulic utilities, the pulp and the paper industry are faced with high maintenance and down time due to the aged excitation system. For the life extension of the aged power plants, the static excitation system with SCPT type had been developed by KEPRI(Korea Electric Power Research Institute) This paper will discuss the design conception and the application results of system which includes the phase controlled rectifiers of the shunt type, SCPT and redundant analog controller.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2002.08a
• /
• pp.1015-1019
• /
• 2002

The deposition of $SrGa_2S_4$ thin film phosphors doped with Ce or Eu aiming at application for FEDs has been carried out by a multi-source deposition technique. A $SrGa_2S_4$ phase was formed by annealing process and $SrGa_2S_4$ thin films which were deposited using a $Ga_2S_3/Sr$ flux ratio larger than 50 and annealed in $H_2$S showed luminance and luminous efficiency of about 1700 cd/$m^2$ and 2.95 lm/W, respectively, with (0.13, 0.10) chromaticity in the activation with Ce, and about 4000 cd/$m^2$ and 7.05 lm/W, respectively, with (0.36, 0.60) under excitation with 3 kV and 60A/$cm^2$. The results obtained this experiment demonstrate the potential of $SrGa_2S_4$ thin film phosphors for FED screens.

• Journal of Information Display
• /
• v.8 no.4
• /
• pp.1-4
• /
• 2007

In the present study, we propose Monte Carlo simulation that takes into consideration the interface phenomena between liquid crystal and substrate. We use rigid model molecules of liquid crystal and substrate. Interface is generated using potential field that induces decomposition of molecules. We use hard spherocylinders as model liquid crystal molecules. Substrate is modeled as region composed of shorter spherocylinders. Our results show that there is a case in which nematic order is reinforced in the vicinity of rubbed substrate.

• Journal of Communications and Networks
• /
• v.16 no.6
• /
• pp.667-676
• /
• 2014

Connectivity is a crucial quality of service measure in wireless sensor networks. However, the network is always at risk of being split into several disconnected components owing to the sensor failures caused by various factors. To handle the connectivity problem, this paper introduces an in-advance mechanism to prevent network partitioning in the initial deployment phase. The approach is implemented in a distributed manner, and every node only needs to know local information of its 1-hop neighbors, which makes the approach scalable to large networks. The goal of the proposed mechanism is twofold. First, critical nodes are locally detected by the critical node detection (CND) algorithm based on the concept of maximal simplicial complex, and backups are arranged to tolerate their failures. Second, under a greedy rule, topological holes within the maximal simplicial complex as another potential risk to the network connectivity are patched step by step. Finally, we demonstrate the effectiveness of the proposed algorithm through simulation experiments.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2017.05a
• /
• pp.90-90
• /
• 2017

Cold spray (Cold gas dynamic spray, kinetic spray) is the latest spray coating process that is known as solid state deposition process. In cold spray, inert gases (typically nitrogen and helium) accelerate powder particles prior to impact onto the substrate. Accelerating particles start to deposit onto the substrate after reaching certain critical velocities depending on the coating materials and substrate. Since process gas temperatures are kept below to melting temperature of the coating materials, it is possible to spray temperature sensitive materials such as copper and titanium, nanocrystal materials, and amorphous metals without affecting the phase change and oxide formation. It is also possible to deposit thick coatings because cold spray coatings present compressive residual stresses. This ability to deposit thick coatings is suitable to repair or rebuild parts as an additive manufacturing process. In this presentation, cold spray is introduced and compared to other additive manufacturing processes such as laser and electron beam based processes. It is also presented some applications especially in the view point of additive manufacturing process.

• Journal of Korea Foundry Society
• /
• v.36 no.6
• /
• pp.181-186
• /
• 2016

The typical microstructure of Al-5%Mg-2%Zn cast alloy mainly consists of an aluminum matrix with a small amount of AlMgZn 2nd phase. The secondary dendrite arm spacing and the grain size of the cast alloy tend to be inversely proportional to the section thickness of casting; however, the tensile properties cannot be said to be clearly related to the cast microstructure. After T6 heat treatment, the tensile strength of the alloy was enhanced significantly. TEM analysis results show that very fine AlMgZn precipitates were formed after the heat treatment. The corrosion resistance, measured according to the corrosion potential, was found to increase slightly after the conducting of heat treatment.