• Proceedings of the Korean Society For Composite Materials Conference
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• 2003.04a
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• pp.31-36
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• 2003

Recently, composite materials are widely used for nozzle, pressure vessel, skins of satellite and many structures under condition of high temperature due to good thermal characteristics such as low CTE, heat-resistance, etc. Fiber optic sensors, especially FBG(fiber Bragg grating) sensors, can be a good counterproposal of strain gages for the measurement of material properties of composites under high temperature. In this research, T700/Epoxy specimens with embedded FBG sensors were fabricated and tested at the Instron with thermal chamber from room temperature to $400^{\circ}C$. The effects of embedding optical fiber on material properties were also verified. And, the experimental results were discussed and analyzed by microphotographs of the composite specimen.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05c
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• pp.36-40
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• 2002

This paper presents the results of a investigation, a development of the measuring system for grounding properties in live-line. The importance of the grounding system and it's property has been increased with the development, enlarge in capacity, of electrical industry. Moreover, with the rapid growth of communication and precision industry, now, we should consider the grounding properties to ensure the stable and/or safe operation. But the conventional measuring system is not proper to measure the grounding properties of the system, voltage applied. So, in this investigation, we proposed a new method for live-line measurement and develope the system. And through the field test we could confirm the superior performance of th developed system.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.11
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• pp.981-986
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• 2014

Printed electronics devices are made of several sets of printed patterns. The quality or printability of the printed patterns determines the electrical performance of such devices. Moreover, control of the printability determines the reliability of such devices. Despite its importance, few studies have been reported for the measurement of the printed patterns to evaluate their printability. In this study, a measurement method is proposed for printed patterns, including the definition of the properties to be measured, and the related software is described. The proposed method measures the width, pinholes, and edge waviness and evaluates the printability of the patterns quantitatively. The proposed measurement method could be an efficient tool to evaluate and enhance the printability of printed patterns in printed electronics.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.5
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• pp.140-147
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• 2008

In this study, a carbon nanotube probe (CNT probe) is proposed as a mechanical force transducer for the measurement of pico-Newton (pN) order force in biological applications. In order to measure nantube's displacement in the air or liquid environment, the fabrication of a CNT probe with tip-specific loading of fluorescent dyes is performed using tip- specific functionalization of the nanotube and chemical bonding between dyes and nanotube. Also, we experimentally investigated the mechanical properties of the CNT probe using electrostatic actuation and fluorescence microscope measurement. Using fluorescence measurement of the tip deflection according to the applied voltage, we optimized the bending stiffness of the CNT probe, therefore determined the spring constant of the CNT probe. The results show that the spring constant of CNT probes is as small as 1 pN/nm and CNT probes can be used to measure pN order force.

• Korean Chemical Engineering Research
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• v.48 no.1
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• pp.93-97
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• 2010

In this study, we have measured the thermo-physical properties of pure organic phase change materials (PCMs) and their mixtures which have the melting points from 0 to $15^{\circ}C$ by using a modified T-history method. These organic PCMs can be used as coolant materials for packaging and shipping of vaccines. Through measuring the thermophysical properties of pure paraffins, we were able to know that we could improve the reliability of measurement if we considered the melting point of each material and subsequently decided an optimum coolant temperature for each system. The modified T-history method showed a potential usefulness for reliably measuring thermo-physical properties of organic mixtures with avoiding possible inaccuracy of measurement due to using a small amount of sample at DSC measurement.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.6 no.2
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• pp.22-27
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• 2007

In this study, the two methods of stiffness measurement(Spring constant) of cantilever were proposed for quantitative measurement in Atomic Force Microscopy(AFM). As the 1st method for the measurement of stiffness, the probe method, which is used in the measurement of the semiconductor mechanical and electrical properties, was applied to the measurement of the cantilever. Experiments by the probe method were performed finding the resistance value of cantilever. As the results, the resistance was measured differently along with the dimension and the thickness of cantilever that determined the stiffness(spring constant) of the lever. As the 2nd method, the vibration characteristics(Dunkerley expression) is used to obtain the stiffness of the complex structure which is combined by AFM cantilever and the standard cantilever. We measured the resonant frequency from the complex structure using the micro stages and stereo microscope. As the results, we confirmed that the vibration characteristics(Dunkerley expression) is effected the micro complex structure of AFM cantilever.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.334.2-334.2
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• 2016

Silicon nitride (SiNx:H) films are generally used as passivation layer on solar cell and they are usually made by plasma enhanced chemical vapor deposition (PECVD). In this study, we investigated the properties of silicon nitride (SiNx:H) films made by PECVD. Effects of mixture ratio of process gases with silane (SiH4) and ammonia (NH3) on the passivation qualities of silicon nitride film are evaluated. Passivation properties of SiNx:H are focused by making antireflection properties identical with thickness and refractive index controlled. The absorption coefficient of each film was evaluated by spectrometric ellipsometery and the minority carrier lifetimes were evaluated by quasi-steady-state photo-conductance (QSSPC) measurement. The optical properties were obtained by UV-visible spectrophotometer. The interface properties were measured by capacitance-voltage (C-V) measurement and the film components were identified by Fourier transform infrared spectroscopy (FT-IR) and Rutherford backscattering spectroscopy detection (RBS) - elastic recoil detection (ERD).

• Journal of Biosystems Engineering
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• v.42 no.3
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• pp.199-216
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• 2017

Purpose: This study reviewed the major nondestructive measurement techniques used to assess internal properties of agricultural materials that significantly influence the quality, safety, and value of the products in markets. Methods: Imaging technologies are powerful nondestructive analytical tools that possess specific advantages in revealing the internal properties of products. Results: This review was exploring the application of various imaging techniques, specifically, hyperspectral imaging (HSI), magnetic resonance imaging (MRI), soft X-ray, X-ray computed tomography (XRI-CT), thermal imaging (TI), and ultrasound imaging (UI), to investigate the internal properties of agricultural commodities. Conclusions: The basic instruments used in these techniques are discussed in the initial part of the review. In the context of an investigation of the internal properties of agricultural products, including crops, fruits, vegetables, poultry, meat, fish, and seeds, various extant studies are examined to understand the potential of these imaging technologies. Future trends for these imaging techniques are also presented.

• Structural Engineering and Mechanics
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• v.20 no.1
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• pp.21-43
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• 2005

Masonry is a composite non-homogeneous structural material, whose mechanical properties depend on the properties of and the interaction between the composite components - brick and mortar, their volume ratio, the properties of their bond, and any cracking in the masonry. The mechanical properties of masonry depend on the orientation of the bed joints and the stress state of the joints, and so the values of the shear modulus, as well as the stiffness of masonry structural elements can depend on various factors. An extensive testing programme in several countries addresses the problem of measurement of the stiffness properties of masonry. These testing programs have provided sufficient data to permit a review of the influence of different testing techniques (mono and bi-axial tests), the variations caused by distinct loading conditions (monotonic and cyclic), the impact of the mortar type, as well as influence of the reinforcement. This review considers the impact of the measurement devices used for determining the shear modulus and stiffness of walls on the results. The results clearly indicate a need to re-assess the values stated in almost all national codes for the shear modulus of the masonry, especially for masonry made with lime mortar, where strong anisotropic behaviour is in the stiffness properties.

• Advances in materials Research
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• v.13 no.3
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• pp.211-220
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• 2024

Polylactic acid or polylactide (PLA) is a biodegradable thermoplastic that can be produced from renewable material to create various components for industrial purposes. In 3D printing technology, PLA is used due to its good mechanical, electrical, printing properties, environmentally friendly and non-toxic properties. However, the physical properties and excellent electrical insulation properties of PLA have limited its application. In this study, with the carbon black (CB) as filler added into PLA, the lattice spacing and morphology were investigated by using X-ray diffraction (XRD) and scanning electron microscope (SEM), respectively. The physical properties of PLA-carbon composite were evaluated by using tensile test, shore D hardness test and density and voids measurement. Impedance test was conducted to investigate the electrical properties of PLA-Carbon composites. The results demonstrate that the inclusion of carbon black as filler enhances the physical properties of the PLA-carbon composites, including tensile properties, hardness, and density. The addition of carbon black also leads to improved electrical conductivity of the composites. Better enhancement toward the electrical properties of PLA-carbon composites is observed with 1wt% of carbon black in N774 grade. The N550 grade with 2wt% of carbon black shows better improvement in the physical properties of PLA-carbon composites, achieving 10.686 MPa in tensile testing, 43.330 in shore D hardness test, and a density of 1.200 g/cm3 in density measurement. The findings suggest that PLA-carbon composites have the potential for enhanced performance in various industrial applications, particularly in sectors requiring improved physical and electrical properties.