• E2M - 전기 전자와 첨단 소재
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• 제2권1호
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• pp.14-24
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• 1989

본 연구에서는 1-3형 PZT/Epoxy 압전복합재료를 제조하고 이에 대한 D-E 곡선, 펄스응답특성 및 유중발생전압특성 등을 조사하였다. 압전복합재료의 음향임피던스는 PZT체적비가 증가함에 따라 비례적으로 증가하였다. 그리고 펄스응답특성은 단일상 PZT의 특성에 비하여 아주 양호하게 나타났으며 PZT 체적비가 40% 이상에서는 펄스응답특성이 거의 일정하게 되었다. 유중에서의 발생전압은 PZT체적비, 시편두께 그리고 유중압력이 증가함에 따란 비례적으로 증가하였다. 이들의 결과는 초음파 트랜스듀서 제작에 좋은 자료가 될 것으로 생각한다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 봄 학술발표회 논문집
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• pp.353-358
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• 2001

The cement concrete pavements are designed twenty years of performance life in Korea. At the present time, some expressways have been elapsed seventy percent of performance life which are detecting local failures. The most repair methods using to repair failures are partial depth repair and full section repair. These methods are most important bonding strength between rapid curing materials and substrate concrete pavements. This study was performed to evaluate bonding strength of the composites section made of rapid curing material and substrate concrete pavements. The pull-out tester was used to test bonding strength for the composites section made of each materials. In the results of the test, the bonding strength values of the epoxy mortar and acrylic mortar are higher than those of the other materials. The performance life of repaired section is affected by various factor. The bonding strength of bonded composites section may be affect the performance life, significantly.

• 한국재료학회지
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• 제3권4호
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• pp.395-402
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• 1993

A newly designed torsion pendulum operating at high pressures and various temperatures has been constructed. The High Pressure Torsion Pendulum(HPTP) is capable of containing gaseous pressure to 690MPa(100, 000psi) and operating at temperatures from-$100^{\circ}C$ to $300^{\circ}C$. A glass fiber braid is installed between two sample holders to accommodateliquid samples. The HPTP was fully automated and computerized using an IBM-AT personal computer to control initiation of oscillation, collect digitized data, and calculate the shear and loss moduli from damped curves, The curing process of an epoxyamine(DGEBA-DDS) system under various pressures up to 124 MPa(18, 000 psi) at $150^{\circ}C$has been successfully carried out and some results are presented.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2003년도 추계학술발표강연 및 논문개요집
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• pp.149-149
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• 2003

This paper presents the work peformed in a program developing composite material which properties satisfy structural and thermal requirements for aircrafts and spacecrafts. In the aerospace vehicle structures, the specific strength of the materials is one of the important requirements and this is why polymer matrix composite material with reinforced carbon fiber is widely used. However, the mechanical properties of the composite material have been known to be dependent on processing and this difficulties in evaluation have caused a lot of mechanical tests for each batch.

• 한국인쇄학회지
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• 제21권2호
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• pp.55-65
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• 2003

A novel evaluation method is investigated for UV curing process in printing system. The method is based on the measurement of conducivity change by the photopolymerization of UV curable inks and paints. It is found that the decrease of conductivity is caused by photopolymerization of epoxy monomer during UV curing process of ink film and the by the rate of UV curing. It is possible to make the dynamical evaluation the curing rate of UV curable ink in curing process by this method.

• Smart Structures and Systems
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• 제17권5호
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• pp.795-817
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• 2016

A non-contact, in-situ and non-invasive technique for health monitoring of submerged fiber reinforced polymers (FRP) laminates has been developed using ultrasonic guided waves. A pair of mobile transducers at specific angles of incidence to the submerged FRP specimen was used to excite Lamb wave modes. Lamb wave modes were used for comprehensive inspection of various types of manufacturing defects like air gaps and missing epoxy, introduced during manufacturing of FRP using Vacuum Assisted Resin Infusion Molding (VARIM). Further service induced damages like notches and surface defects were also studied and evaluated using guided waves. Quantitative evaluation of transmitted ultrasonic signal in defect ridden FRPs $vis-{\grave{a}}-vis$ healthy signal has been used to relate the extent of damage in FRPs. The developed technique has the potential to develop into a quick, real time health monitoring tool for judging the service worthiness of FRPs.

• 한국인쇄학회지
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• 제22권2호
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• pp.37-54
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• 2004

IPNs have interpenetrating motion and phase separation behavior of independent polymers, respectively, and also these are affected by the physical interaction of polymer components. First of all, 2- and 3-component IPNs based on PU are prepared by combination with two or three components of PU, PMMA, PS and epoxy resin. And then the entire physical properties concerning morphological and mechanical behaviors of these IPNs are measured by employing FT-IR, SEM, Rheovibron, and DSC, etc. Compared with pure component, Tg's of IPN are shifted to higher temperature in all IPN kinds, and these are considered in attribution to internal movement of glass transition temperature or partial phenomenon of interpenetration. Rheovibron measurement results in a broader distribution with peaks of tan${\delta}$ or E", and this morphologically represents a medium degree of partially mixed IPNs in confirmation of SEM photographs.

• 대한전기학회논문지
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• 제36권7호
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• pp.447-452
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• 1987

In this paper, the dependence of piezoelectric properties in the 0-3 composite system of piezoelectric-ceramics polymer materials on particle size of ceramics were investigated. Radial mode and thickness mode of composite were observed similar to single phase of piezoelectric ceramics. The measured values of dielectric constant and dissipation factor were dependent on particle size, which increased with the increasing particle size. the planar coupling factor, thickness coupling factor and thickness frequency constant with the particle size were almost constant, while planar frequency constant increased. The thickness coupling factor decreased with the increasing thickness of specimen. It is found that maximum voltage coeffidient was calculated on the specimen with particle size smallar than 46 ${\mu}m$.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.111-111
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• 2010

The mold transformers have been widely used in underground substations in large building and have some advantages in comparison to oil-transformer, that is low fire risk, excellent environmental compatibility, compact size and high reliability. In addition, the application of mold transformer for outdoor is possible due to development of epoxy resin. The mold transformer generally has cooling duct between low voltage coil and high voltage coil. A mold transformer made by one body molding method has been developed for small size and low loss, but it needs some cooling method because heat radiation between each winding is difficult. In this paper, the temperature distribution and thermal stress analysis of H class 100kVA pole cast resin transformer for power distribution are investigated by FEM program.

• Journal of Mechanical Science and Technology
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• 제16권5호
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• pp.666-675
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• 2002

Piezoelectric Fiber Composites with Interdigitated Electrodes (PFCIDE) were previously introduced as an alternative to monolithic wafers with conventional electrodes for applications of structural actuation. This paper is an investigation into the performance improvement of piezoelectric fiber composite actuators by changing the matrix material. This paper presents a modified micro-electromechanical model and numerical analyses of piezoelectric fiber/piezopolymer matrix composite actuator with interdigitated electrodes (PFPMIDE). Various concepts from different backgrounds including three-dimensional linear elastic and dielectric theories have been incorporated into the present linear piezoelectric model. The rule of mixture and the modified method to calculate effective properties of fiber composites were extended to apply to the PFPMIDE model. The new model was validated when compared with available experimental data and other analytical results. To see the structural responses of a composite plate integrated with the PFPMIDE, three-dimensional finite element formulations were derived. Numerical analyses show that the shape of the graphite/epoxy composite plate with the PFPMIDE may be controlled by judicious choice of voltages, piezoelectric fiber angles, and elastic tailoring of the composite plate.