• Food Science and Biotechnology
• /
• v.16 no.2
• /
• pp.234-237
• /
• 2007

Water resistance of three biopolyester films, such as poly-L-lactate (PLA), poly-hydroxybutyrate-co-valerate (PHBV), and Ecoflex, and low density polyethylene (LDPE) film was investigated by measuring contact angle of various probe liquids on the films. The properties measured were initial contact angle of water, dynamic change of the water contact angle with time, and the critical surface energy of the films. Water contact angle of the biopolyester films ($57.62-68.76^{\circ}$) was lower than that of LDPE film ($85.19^{\circ}$) indicating biopolyester films are less hydrophobic. The result of dynamic change of water contact angle also showed that the biopolyester films are less water resistant than LDPE film, but much more water resistant than cellulose-based packaging materials. Apparent critical surface energy for the biopolyester films (35.15-38.55 mN/m) was higher than that of LDPE film (28.59 mN/m) indicating LDPE film is more hydrophobic.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2016.05a
• /
• pp.175-176
• /
• 2016

In this study, research is in order to prevent the defects that occur when the polished tiles construction. For material to be used when the polishing tile construction, trying to evaluate the shrinkage characteristics when the environmental conditions change. Depending on the material used for the shrinkage characteristics evaluation results, the difference between the change values of the length of the drying shrinkage becomes large. Therefore, there is a need for the construction method with consideration of the characteristics of the materials used.

• 연구논문집
• /
• s.33
• /
• pp.167-174
• /
• 2003

Alloy 713LC was developed to improve the tensile strength and ductility by reducing the carbon content of Alloy 713C. As Alloy 713LC was designed to minimize the mechanical property change with process conditions, it is generally utilized in the parts which have thick and thin sections simultaneously. In the thick and the thin sections, quite different properties are required. Consequently it is essential to crucially control the local mechanical properties of a parts by optimizing the process condition and heat treatment. In this research, high temperature mechanical properties including creep-rupture and strain-control low cycle fatigue were investigated together with the microstructural variations with heat treatment. Failure mechanism was also analyzed by observing the fracture surface to correlate the variation of mechanical properties with the microstructural change.

• Proceedings of the IEEK Conference
• /
• 2006.06a
• /
• pp.469-470
• /
• 2006

Surface Acoustic Wave(SAW) devices can be used to as wireless sensor elements, called SAW transponders, for measuring shysical quantities such as temperature that do not need any power supply and may be accessed wirelessly. SAW devices were fabricated on Y-Z $LiNbO_3$ piezoelectric substrate with a good temperature coefficient property. The signal response of SAW sensor on the temperature change were compared. To measure the change of SAW velocity. Temperature changed form $20^{\circ}C$ to $400^{\circ}C$ was linearly changed, the SAW sensor is application to the temperature sensor.

• Journal of the Korean Ceramic Society
• /
• v.29 no.10
• /
• pp.806-814
• /
• 1992

The aim of this study was to investigate the change in compressive strength, freacture behavior and degradation of piezoelectric properties with compressive cyclic loading in Pb(Zr, Ti)O3 of tetragonal, morphotropic phase boundary and rhombohedral composition. The highest compressive strength was found in rhombohedral composition. After poling treatment the strength increased by 8.4% and 6.5% in tetragonal and morphotropic phase boundary compositions respectively while changed little in rhombohedral. The increase of compressive strength after poling treatment is believed to be due to the internal stress around grain boundary by domain alginment toward electric field direction in the microstructures having tetragonality and the occurrence of domain switching to the direction perpendicular to electrical field during fracture. Fracture mode relatively change from transgranular to intergranular was observed in the large grain sized tetragonal and morphotropic phase boundary compositions before and after poling but the transgranular fracture mode always remained in the rhombohedral composition. From the X-ray diffractometer analysis the domains parallel to the electric field direction is known to undergo rearrangement during the cyclic loading into random direction that is responsible for the degradation of piezoelectric property.

• Proceedings of the IEEK Conference
• /
• 2002.07c
• /
• pp.1764-1767
• /
• 2002

Recent explosive increases in information 'volume have led to a rapid development or a change of information technology which stores, searches, and manages a vast amount of information. It is considered that an effective share and utilization of a large amount of digital information produced by work performances is a pivotal element which can make decisive contributions to a great success of business management. This common property of information reflects a changing social paradigm including a change of business processes. This paper is aimed at designing and embodying the construction of knowledge base in an efficient project management system using unsupervised data mining techniques in order to extract information and utilize it as knowledge about standard data (statistical data, template etc.,), size prediction and a danger precaution notice which are needed for a plan and a scheduling of a new project from data coming from already-established projects.

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.63 no.4
• /
• pp.327-332
• /
• 2014

In this paper, the temperature distribution according to the property change of the insulating oil of the power transformer and max temperature were predicted through the ductility interpretation which heat-flow is coupled. By using CFD (Computation Fluid Dynamics) for the interpretation, the temperature distribution of 154kV the class single phase power transformer was predicted. The power loss causing the temperature rise of the transformer was changed to the heat source and we used as the input value for the heat-flow analysis. The temperature distribution was predicted according to the change of the density, specific heat, thermal conductivity and viscosity, that is the ingredient having an effect on the temperature rise of the transformer oil. The mineral oil of 4 kinds used in domestic and international based on the interpreted result was selected and the temperature distribution according to each load and Hot Spot temperature was predicted.

• Kyungpook Mathematical Journal
• /
• v.46 no.1
• /
• pp.145-152
• /
• 2006

In this paper, we study a class of strongly nonlinear implicit complementarity problems in the setting of Hilbert spaces H (not necessarily Hilbert lattices). By using the property of the projection and a suitable change of variables, we establish the equivalence between the strongly nonlinear implicit complementarity problem and the fixed point problem in H. Moreover, we use this equivalence and the fixed point theorem of Boyd and Wong to prove the existence and uniqueness of solutions for the strongly nonlinear implicit complementarity problem in H.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2004.11a
• /
• pp.789-792
• /
• 2004

This study aims to detect only voids and estimate the cross-sectional size and thickness of voids using radar. A new method based on radar image processing is carried out with various void sizes and depths. The regression relationship between void size which has different depth and the amplitude characteristics of the radar return is considered in a new method of this research. For the purpose of examining; this regression relationship, experiments with change of void depth, surface area and thickness were carried out. Finally, the threshold value for image processing which aims to represent only voids to be fitted size (width) can be obtained. As the results, a proposed method in this study has a possibility of detecting only voids and estimating void size and thickness with good accuracy.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2013.11a
• /
• pp.150-151
• /
• 2013

Recently, the internal space organization of the building changes to the frame construction and flat slab construction in the wall type structure. And the use of light weight panel changing the internal joint use easily is increased. Therefore, in this research, the length change characteristic that the magnesium chloride addition rate reaches to the magnesium curing body tries to be studied. It could confirm according to the length change specific result that the magnesium chloride amount of addition reaches to the magnesium oxide curing body to expand. And the thing described below was the large-scale expansion the magnesium oxide addition rate 60%. And it showed up as 50, 40, 30, 20, and order of 10s (%). It could look at to form the hydrate of the SEM picture result needle-shaped of the Hardened.