• Journal of Korea Water Resources Association
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• v.32 no.2
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• pp.163-176
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• 1999

Hydrology-based topographical informations generated by GIS techniques could be changed according to the selection of base map, algorithm of extraction, and so on. The purpose of this paper is to investigate the variation of SCS CN extracted by GIS technique and to propose the effective strategy for applying GIS to the rainfall-runoff simulation in ungaged basin. For experimental implementation, GIS spatial data, such as reconnaissance soil map, detailed interpretative soil map, landuse planning map and remotely sensed data(Landsat TM), were collected and generated to calculate the amount of effective rainfall in Pyungchang river basin. In applying SCS Runoff Curve Number to the test basin, the hydrological attribute data were analyzed. In addition, the characteristics of runoff responses according to the selection of GIS spatial data for SCS CN were reviewed. This study shows the applicability of GIS techniques to runoff simulation in ungaged basin by comparing with the measured flood hydrograph. It has been found that the detained interpretative soil map and remote sensing data are appropriate for calculating of SCS CN.

• Journal of Adhesion and Interface
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• v.21 no.4
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• pp.162-167
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• 2020

The skin-inspired multimodal soft sensors have been developed through multidisciplinary approaches to mimic the sensing ability with high sensitivity and mechanical durability of human skin. For practical application, although the stimulus discriminability against a complex stimulus composed of various mechanical and thermal stimuli experienced in daily life is essential, it still shows a low level actually. In this paper, we first introduce the operating mechanisms and representative studies of the unimodal soft sensor, and then discuss the recent research trend in the multimodal soft sensors and the stimulus discriminability.

• Journal of Korea Water Resources Association
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• v.56 no.4
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• pp.235-243
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• 2023

Due to the revision of the River Act and the enactment of the Act on the Investigation, Planning, and Management of Water Resources, a regular bed change survey has become mandatory and a system is being prepared such that local governments can manage water resources in a planned manner. Since the topography of a bed cannot be measured directly, it is indirectly measured via contact-type depth measurements such as level survey or using an echo sounder, which features a low spatial resolution and does not allow continuous surveying owing to constraints in data acquisition. Therefore, a depth measurement method using remote sensing-LiDAR or hyperspectral imaging-has recently been developed, which allows a wider area survey than the contact-type method as it acquires hyperspectral images from a lightweight hyperspectral sensor mounted on a frequently operating drone and by applying the optimal bandwidth ratio search algorithm to estimate the depth. In the existing hyperspectral remote sensing technique, specific physical quantities are analyzed after matching the hyperspectral image acquired by the drone's path to the image of a surface unit. Previous studies focus primarily on the application of this technology to measure the bathymetry of sandy rivers, whereas bed materials are rarely evaluated. In this study, the existing hyperspectral image-based water depth estimation technique is applied to rivers with vegetation, whereas spatio-temporal hyperspectral imaging and cross-sectional hyperspectral imaging are performed for two cases in the same area before and after vegetation is removed. The result shows that the water depth estimation in the absence of vegetation is more accurate, and in the presence of vegetation, the water depth is estimated by recognizing the height of vegetation as the bottom. In addition, highly accurate water depth estimation is achieved not only in conventional cross-sectional hyperspectral imaging, but also in spatio-temporal hyperspectral imaging. As such, the possibility of monitoring bed fluctuations (water depth fluctuation) using spatio-temporal hyperspectral imaging is confirmed.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.22 no.1
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• pp.89-103
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• 2009

This study investigates the applicability of the time reversal concept in modem acoustics to the Lamb waves, which have been widely studied for defect detection in plate-like structures. According to conventional time reversal acoustics, an input signal can be reconstructed at an excitation point if an output signal recorded at another point is reversed in the time domain and emitted back to the original source point. However, the application of a time reversal process(TRP) to Lamb wave propagations is complicated due to velocity and amplitude dispersion characteristics of Lamb waves and reflections from the boundaries of a structure. In this study, theoretical investigations are presented to better understand the time reversibility of Lamb waves. In particular, the effects of within-mode dispersion, multimode dispersion, amplitude dispersion, and reflections from boundaries on the TRP are theoretically formulated. Simple numerical case studies are conducted to validate the theoretical findings of this study.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.241.1-241.1
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• 2011

Numerous possible applications for $ZrO_2$ nanotubes exist such as for catalyst support structures, for sensing or for applications as a solid state electrolyte. Especially, because of a large specific surface area, high efficiency for solid oxide fuel cell (SOFC) application at low temperature can be expected for nanotublar structures in even small size. A zirconium precursor, Tetrakis (ethylmethylamino) zirconium, TEMAZr and $H_2O$ oxidant were used to deposit$ZrO_2$ thin films on an anodized aluminum oxide (AAO) templates having sub-100nm cylindrical pores by atomic layer deposition (ALD) in the temperature range of 150~250$^{\circ}C$. The crystalline structures of as-prepared and post-annealed $ZrO_2$ nanotubes were characterized by x-ray diffraction and high-resolution transmission electron microscopy. The as-prepared samples at $150^{\circ}C$ and $200^{\circ}C$ were showed amorphous, whereas a mixed phase of tetragonal, monoclinic and amorphous polymorph was observed at $250^{\circ}C$. In the bulk, zirconia remains monoclinic phase up to $1,175^{\circ}C$, however, $ZrO_2$ nanotubes were showed tetragonal phase upon post thermal treatments merely at $400^{\circ}C$. This trend may be indicative of high-curvature surfaces of nanotubes and thereby the presence of intrinsic compressive strain. The amount of amorphous structures in the mixed phase as well as as-grown $ZrO_2$ nanotubes were also gradually decreased by subsequent heat treatment.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.6 no.3
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• pp.439-448
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• 1996

The possibility of application or the transparent BK10 glass fiber/PMMA composites as a temperature-or wavelength-sensors was studied. Measurement of diameter and refractive index for glass fibers to be reinforced to PMMA as a function of drawing speed and temperature was done and the appropriate coating methods and solvent for coupling agent was researched. $T_{max%}$ value at which the maximum transmission for the composites occurs could be controlled to be in $31~50^{\circ}C$ by the processing factors such as fiber diameter, fiber vol%, molecular wt. of PMMA. Furthermore, with different wavelength other than 589.3 nm, the $T_{max%}$ value could be controlled to be in $35~55^{\circ}C$. For the sensibility of wavelength for the composites, there was not a wavelength ($\lamda_{max%}$) showing maximum transmission.

• Journal of the Korean Geographical Society
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• v.47 no.2
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• pp.282-296
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• 2012

This study compared effects of spatial resolution ratio in image fusion by Korea Multi-Purpose SATellite 2 (KOMPSAT II), also known as Arirang-2. Image fusion techniques, also called pansharpening, are required to obtain color imagery with high spatial resolution imagery using panchromatic and multi-spectral images. The higher quality satellite images generated by an image fusion technique enable interpreters to produce better application results. Thus, image fusions categorized in 3 domains were applied to find out significantly improved fused images using KOMPSAT 2. In addition, all fused images were evaluated to satisfy both spectral and spatial quality to investigate an optimum fused image. Additionally, this research compared Pixel-Based Image Analysis (PBIA) with the GEOgraphic Object-Based Image Analysis (GEOBIA) to make better classification results. Specifically, a roof top of building was extracted by both image analysis approaches and was finally evaluated to obtain the best accurate result. This research, therefore, provides the effective use for very high resolution satellite imagery with image interpreter to be used for many applications such as coastal area, urban and regional planning.

• Composites Research
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• v.17 no.4
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• pp.61-67
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• 2004

Nondestructive damage sensitivity on single-basalt fiber/epoxy composites was evaluated by micromechanical technique and acoustic emission (AE). Piezoelectric lead-zirconate-titanate (PZT), polyvinylidene fluoride (PVDF) and poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) copolymer were used as AE sensor, respectively. In single-fiber composite, the damage sensing with different sensor types were compared to each other. Piezoelectric PVDF polymer sensor was embedded in and attached on the composite, whereas PZT sensor was only attached on the surface of specimen. In case of embedded polymer sensors, responding sensitivity was higher than that of the attached case. It can be due to full constraint inside specimen to transfer elastic wave coming from micro-deformation. For both the attached and the embedded cases, the sensitivity of P(VDF-TrFE) sensor was almost same as that of conventional PVDF sensor.

• Journal of the Korean Association of Geographic Information Studies
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• v.1 no.1
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• pp.109-117
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• 1998

To obtain new information using a single remotely sensed image data is limited to extract various information. Recent trends in the remote sensing show that many researchers integrate and analyze many different forms of remotely sensed data, such as optical and radar satellite images, aerial photograph, airborne multispectral scanner data and land spectral scanners. Korean researchers have not been using such a combined dataset yet. This study intended to apply the technique of integration between optical data and radar data(SAR) and to examine the output that had been obtained through the technique of supervised classification using the result of integration. As a result, we found of better enhanced image classification results by using IHS conversion than by using RGB mixed and interband correlation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.5 no.1
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• pp.60-64
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• 2004

In this paper, we implemented a real-time remote home monitoring system which we have ported the Linux OS and HTTP(Hypertext Transfer Protocol) web server. The GoAhead web server was ported using by ARM cross compiler. And then we used the analog to digital converter ADC0809 for sensing the vii able input signal at widely separated home. We have implemented linux device driver for ADC(Analog to Digital Convertor) and CGI-C(Common Gateway Interface - C language) application program using Client pull method for monitoring real-time changing data. The factor of monitoring is temperature, intensity of illumination and gas's existence. And this system has ability which check the status of out door and gas valve. We have designed the embedded web server system for home emergency monitoring in low cost.