• Korean Journal of Agricultural Science
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• v.38 no.1
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• pp.115-120
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• 2011

20% of total energy use to sustain temperature of building inside. In this reasons, researchers effort to improve the thermal insulation capacity with new wall system. Using appropriate materials and consisting new wall system should considered in energy saving design. OSB(Oriented strand board), Larch lining board used to consist wall system. $2{\sim}6$ Larch lining board has tongue & groove shape for preventing moisture. Comparing with gypsum board and green timber lining board as interior sheathing material, temperature difference of Green timber wall system was bigger than temperature difference of gypsum board wall system. This aspects indicate that Green timber wall system was revealed higher thermal insulation property than gypsum board wall system. Gypsum board portion transfer heat easily because temperature difference gradient of gypsum board wall system was smaller than OSB wall system. Total temperature variation shape of G-4-S and G-6-S show similar model but, temperature variation shape in green timber wall portion assume a new aspect. The purpose of this study was that possibility of thermal insulation variation and new composition of wall system identify to improve thermal insulation performance. In the temperature case, this study shows possibility of improving thermal insulation performance. Humidity, sunshine and wind etc. should considered to determine building adiabatic properties.

• Steel and Composite Structures
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• v.37 no.3
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• pp.341-351
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• 2020

Steel plate shear wall with self-centering energy dissipation braces (SPSW-SCEDB) is a lateral force-resisting system that exhibits flag-shaped hysteretic responses, which consists of two pre-pressed spring self-centering energy dissipation (PS-SCED) braces and a wall plate connected to horizontal boundary elements only. The present study conducted a series of cyclic tests to study the hysteretic performances of braces in SPSW-SCEDB and the effects of braces on the overall hysteretic characteristics of this system. The SPSW-SCEDB with PS-SCED braces only exhibits excellent self-centering capability and the energy loss caused by the large inclination angle of PS-SCED braces can be compensated by appropriately increasing the friction force. Under the combined effect of the two components, the SPSW-SCEDB exhibits a flag-shaped hysteretic response with large lateral resistance, good energy dissipation and self-centering capabilities. In addition, the wall plate is the primary energy dissipation component and the PS-SCED braces provide supplementary energy dissipation for system. The PS-SCED braces can provide up to 90% self-centering capability for the SPSW-SCEDB system. The compressive bearing capacity of the wall plate should be smaller than the horizontal remaining restoring force of the braces to achieve better self-centering effect of the system.

• Journal of the Microelectronics and Packaging Society
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• v.22 no.4
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• pp.77-82
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• 2015

To increase the performance of solid oxide fuel cell operating at intermediate temperature ($600^{\circ}C{\sim}800^{\circ}C$), $Sm_{0.2}Ce_{0.8}O_2$ (SDC) thin layer was applied to the $La_{0.8}Sr_{0.2}Mn_{0.8}Cu_{0.2}O_3$ (LSMCu) cathode by sol-gel coating method. The SDC was employed as a diffusion barrier layer on the yttria-stabilized zirconia(YSZ) to prevent the interlayer by-product formation of $SrZrO_3$ or $La_2Zr_2O_7$. The by-products were hardly formed at the electrolyte-cathode interlayer resulting to reduce the cathode polarization resistance. Moreover, SDC thin film was coated on the cathode pore wall surface to extend the triple phase boundary (TPB) area.

• Advances in Computational Design
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• v.2 no.1
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• pp.43-56
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• 2017

The aim of this paper is to develop software for designing of steel reinforced elastomeric isolator (SREI) according to American Association for State Highway and Transportation Officials Load and Resistance Factor Design (AASHTO LRFD) Specifications. SREI is used for almost all bridge types and special structures. SREI-structures interface defines support boundary conditions and may affect the seismic performance of bridges. Seismic performance of the bridge is also affected by geometrical and materials properties of SREI. The selection of SREI is complicated process includes satisfying all the design constraints arising from code provisions and maximizing performance at the lowest possible cost. In this paper, design stage of SREI is described up to AASHTO LRFD 2012. Up to AASHTO LRFD 2012 analysis and design program of SREI performed different geometrical and material properties are created with C# object-oriented language. SREI-CAD, name of the created software, allows an accurate design for economical estimation of a SREI in a short time. To determine types of SREI effects, two different types of bearings, rectangular and circular with similar materials and dimension properties are selected as an application. Designs of these SREIs are completed with SREI-CAD. It is seen that ensuring the stability of circular elastomer bearing at the service limit state is generally complicated than rectangular bearing.

• Journal of the Korean Vacuum Society
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• v.10 no.4
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• pp.403-410
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• 2001

Acceleration in integration density and speed performance of ULSI circuits require miniaturization of CMOS and interconnections as well as higher current density capabilities for transistors. A leading candidate to substitute Al-alloy is Cu, which has lower resistivity and higher melting point. So we can expect much higher electromigration resistance. In this paper, we are going to explain the major features of EM for MOCVD Cu according to variant conditions. We compared the life time and activation energy of MOCVD Cu with those of I-beam Cu and AA in the same conditions. The electromigration experiments were performed with Cu/Al/TiN multilayer. Experimental results shows that the deposition rate and electromigration characteristics of Cu thin film were improved by the Al interlayer.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.10
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• pp.820-826
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• 2009

The anisotropic phonon conductions with varying Joule heating rate of the silicon film in Silicon-on-Insulator devices are examined using the electron-phonon interaction model. It is found that the phonon heat transfer rate at each boundary of Si-layer has a strong dependence on the heating power rate. And the phonon flow decreases when the temperature gradient has a sharp change within extremely short length scales such as phonon mean free path. Thus the heat generated in the hot spot region is removed primarily by heat conduction through Si-layer at the higher Joule heating level and the phonon nonlocality is mainly attributed to lower group velocity phonons as remarkably dissimilar to the case of electrons in laser heated plasmas. To validate these observations the modified phonon nonlocal model considering complete phonon dispersion relations is introduced as a correct form of the conventional theory. We also reveal that the relation between the phonon heat deposition time from the hot spot region and the relaxation time in Si-layer can be used to estimate the intrinsic thermal resistance in the parallel heat flow direction as Joule heating level varies.

• Tribology and Lubricants
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• v.23 no.4
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• pp.170-174
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• 2007

Wear and scuffing tests were conducted using friction and wear measurement of piston rings and cylinder blocks in low friction diesel engine. The frictional forces, wear amounts and cycles to scuffing in boundary lubricated sliding condition were measured using the reciprocating wear tester. The cylinder blocks were used as reciprocating specimens, and the piston rings with several coatings were used as fixed pin. Several coatings were used such as DLC, TiN, Cr-ceramic and TiAlN in order to improve the tribological characteristics. From the tests wear volume of piston ring surfaces applied various coatings were compared. During the tests coefficients of friction were monitored. Test results showed that DLC coatings showed good tribological properties. TiN and Cr-ceramic coated rings showed good wear resistance properties but produced high friction.

• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.368-371
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• 2006

[ $La_{0.8}Sr_{0.2}Co_{1-x}Mn_xO_3$ ] cathode as a high performance cathode on YSZ electrolyte was studied by analyzing impedance spectra. It was shown that cathode property of $La_{0.8}Sr_{0.2}Co_{1-x}Mn_xO_3$ is bet ter than that of$La_{0.8}Sr_{0.2}CoO_3$. At $700^{\circ}C$ in air environment, $La_{0.8}Sr_{0.2}Co_{0.4}Mn_{0.6}O_3$ cathode on CGO- layered YSZ electrolyte showed very low area specific resistance of $0.14{\Omega}cm^2$, which is low enough for intermediate-temperature sol id oxide fuel cells. This is because material properties of ionic conductivity and thermal expansion compatibility with electrolyte were optimized. Judging from activation energy and oxygen part i al pressure dependance of cathode property, it was noted that oxygen surface exchange kinetics is dominantly influential on cathode property in higher temperature region than $700^{\circ}C$ and oxygen self-diffusion in cathode material is more influential in lower temperature region.

• Structural Engineering and Mechanics
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• v.38 no.4
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• pp.385-403
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• 2011

Continuous deep girders which transmit the gravity load from the upper wall to the lower columns have frequently long end shear spans between the boundary of the upper wall and the face of the lower column. This paper presents the results of tests and analyses performed on three 1:2.5 scale specimens with long end shear spans, (the ratios of shear-span/total depth: 1.8 < a/h < 2.5): one designed by the conventional approach using the beam theory and two by the strut-and-tie approach. The conclusions are as follows: (1) the yielding strength of the continuous RC deep girders is controlled by the tensile yielding of the bottom longitudinal reinforcements, being much larger than the nominal strength predicted by using the section analysis of the girder section only or using the strut-and-tie model based on elastic-analysis stress distribution. (2) The ultimate strengths are 22% to 26% larger than the yielding strength. This additional strength derives from the strain hardening of yielded reinforcements and the shear resistance due to continuity with the adjacent span. (3) The pattern of shear force flow and failure mode in shear zone varies depending on the amount of vertical shear reinforcement. And (4) it is necessary to take into account the existence of the upper wall in the analysis and design of the deep continuous transfer girders that support the upper wall with a long end shear span.

• Structural Engineering and Mechanics
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• v.65 no.6
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• pp.657-678
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• 2018

Sandwich structures are well known for their use in aircraft, naval and automobile industries due to their high strength resistance with light weight and high energy absorption capability. Sandwich beams with soft core are very common and simple structures that are employed in day to day general use appliances. Modeling and analysis of sandwich structures is not straight forward due to the interactions between core and face sheets. In this paper, formulation of Super Convergent finite elements for analysis of the sandwich beams with soft core based on Euler Bernoulli beam theory are presented. Two elements, Eul4d with 4 degrees of freedom assuming rigid core in transverse direction and Eul10d with 10 degrees of freedom assuming the flexible core were developed are presented. The formulation considers the top, bottom face sheets and core as separate entities and are coupled by beam kinematics. The performance of these elements are validated by results available in the published literature. Number of studies are performed using the formulated elements in static, free vibration and wave propagation analysis involving various boundary and loading conditions. The paper highlights the advantages of the elements developed over the traditional elements for modeling of sandwich beams and, in particular wave propagation analysis.