• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.8
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• pp.76-82
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• 2015

A hybrid fiber-optic sensor system which combines fiber Bragg grating sensors and a Michelson interferometer has been constructed and evaluated for condition monitoring of large scale wind turbines. In order to measure multiple stresses applied to wind turbines such as strain, temperature and vibration, the system uses single broadband light source. It addresses both types of sensors, which simplifies the optical setup and enhances the cost-effectiveness of condition monitoring system. An athermal-packaged FBG is used to supply quasi-coherent light, of which coherence length is about 3.28mm, for the Michelson interferometer demodulation. Experimental results demonstrated that the proposed fiber-optic sensor system was capable of measuring strain and temperature with measurement accuracy of 1pm. Also 500~2000Hz vibration signals were successfully analyzed by applying FFT signal processing to interference signals.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.10 no.1
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• pp.16-22
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• 2007

This study was carried out to investigate the effects of shading conditions for appropriate light level for several floricultural plants native to Korea. The results under the different shading levels of 0, 30, 50, 60% and full sun light are as follows; Growth of Miscanthus sinensis and Pennisetum alopecuroides, which are heliophyte plants, were better under 30% shading condition than full sunlight. Higher shading levels was poor than control. Growth of Sedum spectable was decreased when light intensity was decreased. As shading level increased, growth reduction rate in Sedum spectable were higher than that of other species. Growth and ornamental value of Arisaema amurense, which is sciophyte plants, were increased under 50% shading.

• Bulletin of the Korean Chemical Society
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• v.31 no.7
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• pp.1941-1944
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• 2010

The heterojunction structures of BiOCl/$Bi_3O_4Cl$, exhibiting considerable visible-light photocatalytic efficiency, were prepared by a simple wet-chemical process at ambient condition. The prepared nanocomposites were characterized by XRD, TEM, and UV-visible diffuse reflectance spectra. Under visible light (${\lambda}\geq$420 nm) irradiation, BiOCl/$Bi_3O_4Cl$ exhibited an enhanced photocatalytic activity in decomposing 2-propanol (IP) in gas phase and salicylic acid (SA) in aqueous solution, whereas the bare BiOCl and $Bi_3O_4Cl$ showed negligible activities. It is deduced that the remarkable visible-light photocatalytic activity of the BiOCl/$Bi_3O_4Cl$ originates from the hole $(h^+)$ transfer between VB of the $Bi_3O_4Cl$ and BiOCl semiconductors.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.3
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• pp.453-457
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• 2008

We studied on the dependency of parameters which those were used to design a ballast of ICP light source. These parameters were derived from Barkhausen criterion equation about the oscillating condition of ballast. Comparing with a change of turns, we can suggest that a change of l is suitable to control a $I_p$ of an ICP light source. According to the Z-l equation, we can find an optimum rating power of ICP light sources corresponding to l.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.8
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• pp.751-755
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• 2010

In this paper, we proposed an omnidirectional ranging system that is able to obtain $360^{\circ}$ all directional distances effectively based on structured light image. The omnidirectional ranging system consists of laser structured light source and a catadioptric omnidirectional camera with a curved mirror. The proposed integro-differential structured light image processing algorithm makes the ranging system robust against environmental illumination condition. The omnidirectional ranging system is useful for map-building and self-localization of a mobile robot.

• Fashion & Textile Research Journal
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• v.3 no.1
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• pp.31-34
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• 2001

The color difference values of dyed fabrics with colorant in Eucommiae Cortex were as follows; One hour of dyeing depending on pH at $95^{\circ}C$ exhibited colors of dark brown, light brown, light beige and grey. The colors of wool, nylon and silk was darkest brown at pH 3 but light brown or yellow as pH increased. In all dyed fabrics the color was changed to darker brown as time prolonged, however; there was no further color change and value and chroma of wool declined. At pH 3, the increase in temperature turned colors of all dyed fabrics into dark brown from light yellow. As the result of repetitive dyeing, colors of all dyed fabrics gradually turned into darker brown. The methods of mordant resulted in color changes between light yellow and dark brown without various color changes.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.10a
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• pp.416-421
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• 1997

This study was conducted to evaluate durability of high-strength light-weight aggregate concretes which are increasingly demanded recently. Two different artificial light-weight aggregates were used and two levels of high-strength concretes were made using w/c of 33% and 37% for target strength of 500kg/$\textrm{cm}^2$ and 400kg/$\textrm{cm}^2$, respectively. Cylinder specimens($\phi$=10cm and h=20cm) were made and treated with freezing-and-thawing(F/T) cycle at $-18^{\cire}C$ and $4^{\cire}C$. Dynamic modulus of elasticity and surface condition were evaluated with F/T cycle increase. The results showed that durability of the light-weight aggregate concretes was worse than that of conventional concrete, and the light-weight high-strength concrete with w/c=37% had the better durability than the one with w/c=33%.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2012.05a
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• pp.255-256
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• 2012

In this study, strain properties of high strength concrete using light weight aggregate which is widely used in recent years are evaluated. For these purpose, thermal strain, transient creep were measured in prestressed condition as 0, 20, 40% of specimen strength at target temperature with 60MPa specimens which was using normal and light weight aggregate. As a result, light weight aggregate is more advantageous for the control of strain than normal aggregate because of its low thermal expansion.

• Journal of Korean Society for Atmospheric Environment
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• v.21 no.E2
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• pp.49-56
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• 2005

A long-path transmissometer is one of the optical instruments widely used to measure atmospheric light extinction coefficient without enclosing a light beam and perturbing aerosols. Over the past two decades, a number of measurements have been carried out using the long-path transmissometer manufactured by OPTEC, Inc. Calibration of the transmissometer should be performed when any component of the transmissometer system is interchanged or installation condition is changed. For a better calibration of the transmissometer, application of a modified calibration method for the existing neutral density (ND)-filter method was recommended for the computation of the atmospheric transmittance using model MODTRAN 4 in this study. It was revealed that the measured light extinction coefficient from the transmissometer which was calibrated using the existing ND-filter method could be overestimated due to the assumption of the atmospheric transmittance suggested by OPTEC, Inc. The uncertainty of the measured light extinction coefficient from the transmissometer calibrated based on the modified ND-filter method was calculated to be approximately $13Mm^{-1}$.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.04a
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• pp.155-161
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• 1997

This Expriment is performed to describe the properties of the freezing-thawing and to find the method to enhance the freezing-thawing resistance of the high strength light weight aggregates concrete. For this purpose, we made 8 kinds of specimen of concrete mold. The light weight coarse aggregate concrete which contained AE was appeared in good condition and its durability index was more than 90% by the buffer action which owing to entained air. The light weight aggregates concrete which admixture of silca fume, was appeared that the durability index was 46.74% in spite of its high strength. I might conclude that the most important factor for freezing-thawing resistance of high strength light weight aggregate concrete is the entrained air.