• Bulletin of the Korea Photovoltaic Society
• /
• v.7 no.1
• /
• pp.27-32
• /
• 2021

코로나-19 팬데믹으로 인류는 많은 어려움에 처하게 되었다. 그러나 바이러스 감염 예방을 위해 대량 시료에 대한 정확하고 신속한 분석이 필요함에 따라 실험실 자동화 기술의 상용화가 크게 앞당겨졌다. 스마트 랩이란 실험실 자동화를 위한 H/W인 실험실 자동화 시스템(LAS)와 실험 절차 및 데이터를 통합 관리하는 S/W인 실험실 데이터 관리 시스템 (LIMS)의 결합으로 이뤄진 통합 연구 시스템이라고 할 수 있다. 스마트 랩을 통해 사용자는 24시간 연속적인 장비 가동을 통한 분석 물량 확대는 물론 전처리와 같은 반복 작업 감소, 정확도 향상 등의 자동화로 인한 장점과 함께 시험 방법의 동일성 유지, 시료별 이력 추적, 조작 방지 등의 소프트웨어적인 장점을 동시에 얻을 수 있다. 스마트 랩은 지금도 발전하고 있으며 일부 대기업과 연구소에서 도입을 추진하고 있는 태동기라고 할 수 있다. 최근 우리나라가 선도하고 있는 페로브스카이트 태양전지와 같이 수분에 취약한 유무가 복합 재료의 in-line 시험이나 조성의 미세한 조정에 따라 변화하는 물성 변화를 추적 조사하는데 필요한 많은 측정과 데이터 처리 등 태양전지 분야에서도 앞으로 그 활약이 기대된다.

• Proceedings of the Korean Society For Composite Materials Conference
• /
• 2004.04a
• /
• pp.115-118
• /
• 2004

In this paper, a Fiber Bragg Grating (FBG) sensor system for smart structures is described. FBGs are well-suited for long term and extremely severe experiments, where traditional strain gauges fail. In the system, a reflect wave-length measurement method which employs a tunable light source to find out the center wave-length of FBG sensor is used. We applied the FBG system to composite repairing structures and beam column joint of building structure. We also applied the system to nuclear energy power plant for structural integrity test to measure the displacement of the structure under designed pressure and to check the elasticity of the structure by measuring the residual strain. The system works very well and it is expected that it can be used for a real-time strain, temperature and vibration detectors as parts of smart structures.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.39 no.6
• /
• pp.675-689
• /
• 2019

Development of smart construction materials with both self-strain and self-damage sensing capacities is still difficult because of little information about the self-damage sensing source. Herein, we investigate the effects of the matrix strength, fiber geometry, and fiber content on the electrical resistivity of steel-fiber-reinforced cement composites by multi-fiber pullout testing combined with electrical resistivity measurements. The results reveal that the electrical resistivity of steel-fiber-reinforced cement composites clearly decreased during fiber-matrix debonding. A higher fiber-matrix interfacial bonding generally leads to a higher reduction in the electrical resistivity of the composite during fiber debonding due to the change in high electrical resistivity phase at the fiber-matrix interface. Higher matrix strengths, brass-coated steel fibers, and deformed steel fibers generally produced higher interfacial bond strengths and, consequently, a greater reduction in electrical resistivity during fiber debonding.

• Composites Research
• /
• v.28 no.3
• /
• pp.75-80
• /
• 2015

Poly(vinylidene fluoride-trifluoroethylene; P(VDF-TrFE)) is one of the most promising electroactive polymers with numerous application potentials in many fields of industry. Because of its good electro-mechanical properties P(VDF-TrFE) has been used for a number of sensors and actuators and also can be used for monitoring composite structure behaviors as a sensor. Three different ways (Electrical poling, annealing-cooling, and pressing) to enhance ${\beta}$-phase of P(VDF-TrFE) film were carried out. A microscopic analysis was conducted using X-ray diffraction to investigate the effect of such treatments on piezoelectric properties of P(VDF-TrFE) film. From the results, poling, annealing-cooling, and pressing were all effective to enhance ${\beta}$ crystallinity of P(VDF-TrFE) film and the maximum increase rate was 62.80% from 45.29% of the control group.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.34 no.1
• /
• pp.65-73
• /
• 2006

The high temperature occurs due to the combustion gas from engine in unmanned aerial vehicles (UAV). The high temperature may cause serious damages in UAV structure. The Functionally Graded Material (FGM) is chosen as a candidate material of the engine duct structure. A functionally graded material (FGM) is a two- component mixture composed by compositional gradient materials from one material to the other. In contrast, traditional composite materials are homogeneous mixtures, and involve compositions between the desirable properties of the component materials. Since significant proportions of an FGM contain the pure form of each material, the need for compromise is eliminated. The properties of both components can be fully utilized. Thermal stress analysis of FGM layers (20, 40, 60, 80 and 100) is performed in this paper. In addition, the creep behavior of FGM applied in duct structure of an engine is analyzed for better understanding of FGM characteristics.

• Composites Research
• /
• v.20 no.3
• /
• pp.25-30
• /
• 2007

This paper describes the basic design and fabrication of smart skin antenna for phased array applications. The smart skin phased array antenna, of which radiation pattern can be electrically steerable without mechanical rotation, has to meet the both mechanical and electrical performance. The smart skin antenna is a honeycomb sandwich structure to enhance the mechanical performance such as strength, weight and so on. The example of smart skin antenna integrated with radome is designed with the resonant frequency of 5 GHz, circular polarization, 2 by 2 subarray, and a coaxial probe-fed excitation. In addition, the performance of raw microstrip patch antenna uncovered radome is investigate. The fabricated smart skin antenna shows a reasonable performance with gain of 12.2 dBi and frequency bandwidth of 6.4 %.

• Proceedings of the Korean Society For Composite Materials Conference
• /
• 2005.04a
• /
• pp.1-4
• /
• 2005

A higher order zig-zag shell theory is developed to refine accurately predict deformation and stress of smart shell structures under the mechanical, thermal, and electric loading. The displacement fields through the thickness are constructed by superimposing linear zig-zag field to the smooth globally cubic varying field. Smooth parabolic distribution through the thickness is assumed in the transverse deflection in order to consider transverse normal deformation. The mechanical, thermal, and electric loading is applied in the sinusoidal distribution function in the in-surface direction. Thermal and electric loading is given in the linear variation through the thickness. Especially, in electric loading case, voltage is only applied in piezo-layer. The layer-dependent degrees of freedom of displacement fields are expressed in terms of reference primary degrees of freedom by applying interface continuity conditions as well as bounding surface conditions of transverse shear stresses. In order to obtain accurate transverse shear and normal stresses, integration of equilibrium equation approach is used. The numerical examples of present theory demonstrate the accuracy and efficiency of the proposed theory. The present theory is suitable for the predictions of behaviors of thick smart composite shell under mechanical, thermal, and electric loadings combined.

• Journal of the Korean Society for Aviation and Aeronautics
• /
• v.13 no.1
• /
• pp.20-31
• /
• 2005

In this study, subsonic flutter analyses have been conducted for a composite smart UAV with T-tail configuration at the critical flight condition. Detailed three-dimensional finite element model for dynamic analysis is constructed including its nonstructural elements corresponding to installed electronic equipments and fuels. Computational structural dynamics and aeroelastic techniques are conducted using MSC/NASTRAN and originally developed in-house codes. The results for fundamental vibration characteristics and flutter instabilities are presented and compared to each other for different fuel conditions.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.16 no.3
• /
• pp.471-476
• /
• 2021

Soft magnetic composite (SMC) materials based on powder metallurgy have a number of advantages over the conventional electrical steel sheets commonly used in electric machines. Thus, technologies related to these materials have shown significant improvement in recent years. In general, SMCs are magnetically isotropic owing to the shape of the powder, which makes them suitable for the construction of electric machines with three-dimensional flux and complex structures. However, the materials with isotropic magnetic properties (such as SMCs) have complex vector hysteresis; thus, it is very difficult to predict accurate loss properties. Therefore, we manufactured ring-type specimens of electrical steel sheets and SMC, which analyzed their magnetic properties according to the specimen size, and performed the electromagnetic field analysis of a high-speed permanent magnet (PM) motor driven at 800 Hz or higher using the measured magnetic information to compare the core loss of the motor. The reliability of this paper has been verified by measuring the efficiency after manufacturing the motor.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.30 no.1
• /
• pp.49-55
• /
• 2002

In this paper, we present the simulation monitoring of strain and temperature during and after the cure of unsymmetric composite laminate using fiber optic sensors. Fiber Bragg grating/extrinsic Fabry-Perot interferometric (FBG/EFPI) hybrid sensors are used to measure those measurands. The characteristic matrix of the sensor is analytically derived and measurements can be done without sensor calibration. A wavelength-swept fiber laser is utilised as a lighr source. Two FBG/EFPI sensors are embedded in a graphite/epoxy unsymmetric cross-ply composite laminate in different directions and different locations. We perform a real time monitoring of fabrication strains and temperatures at two points of the composite laminate during cure process in an autoclave. Also, the thermal strains and temperatures of the fabricated laminate are measured in a thermal chamber. Through these experiments, we can provide a basis for the efficient smart processing of composite and know the thermal behavior of unsymmetric cross-ply composite laminate.