• Journal of Korean Society of Coastal and Ocean Engineers
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• v.21 no.2
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• pp.154-163
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• 2009

Incident wave angles are conventionally estimated by the directional spectrum analysis of wave data collected from in-situ sensors. The in-situ measurements are limited in monitoring incident wave angles in the wide surf zone, since the techniques are typically expensive, labor-intensive, and point-measuring. In this study, estimation of incident wave angles using wave crest features captured in digital video imagery is proposed to observe incident wave directions over the surf zone. Line signatures of wave crests having high image pixel intensities are extracted by moving an interrogation window to identify high intensity pixels in sequential video images. Wave angles are computed by taking the first derivative of the extracted crest signatures, i.e. local slope of the crest signatures in the two-dimensional physical plane. Compared to the wave angle estimates obtained by the directional spectrum analysis, video-based wave angle estimates show good agreements in general.

• Proceedings of the KSRS Conference
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• 2007.10a
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• pp.629-632
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• 2007

While conventional interferometric SAR (InSAR) technique is an excellent tool for displacement observation, it is only sensitive to one-dimensional deformation along the satellite's line-of-sight (LOS). Recently, a multiple aperture interferogram (MAI) technique has been developed to overcome this drawback. This method successfully extracted along-track displacements from InSAR data, based on split-beam InSAR processing, to create forward- and backward- looking interferograms, and was superior to along-track displacements derived by pixel-offset algorithm. This method is useful to measure along-track displacements. However, it does not only decrease the coherence of MAI because three co-registration and resampling procedures are required for producing MAI, but also is confined to a suitable interferometric pair of SAR images having zero Doppler centroid. In this paper, we propose an efficient and robust method to generate MAI from interferometric pair having non-zero Doppler centroid. The proposed method efficiently improves the coherence of MAI, because the co-registration of forward- and backward- single look complex (SLC) images is carried out by time shift property of Fourier transform without resampling procedure. It also successfully removes azimuth flat earth and topographic phases caused by the effect of non-zero Doppler centroid. We tested the proposed method using ERS images of the Mw 7.1 1999 California, Hector Mine Earthquake. The result shows that the proposed method improved the coherence of MAI and generalized MAI processing algorithm.

• Journal of Korean Society of societal Security
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• v.1 no.3
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• pp.77-81
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• 2008

In this paper, we introduce a multi purpose environmental monitoring system developed as a commercially available standard using the technique of hetero-core spliced fiber optic sensor. The monitoring system has been tested and evaluated in a possible outdoor condition in view of the full scaled operation at actual sites to be monitored. Additionally, the developed system in this work conveniently provides us with various options of sensor modules intended for monitoring such physical quantities as displacement, distortion, pressure, binary states, and liquid adhesion. Two channels of optical fiber line were monitored, in each of which three displacement sensor modules were connected in series, in order to examine the performance to a pseudo-cracking experiment in the outdoor situation, and to clarify temperature influences to the system in terms of the coupling of optical connectors and the OTDR stability. The pseudo-cracking experiment successfully observed the actually given cracks by means of calculation based on the detected displacement values and their geometrical arrangement of the used sensor modules. And the robustness to the temperature is verified in the various temperature change.

• Korean Journal of Construction Engineering and Management
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• v.14 no.5
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• pp.153-163
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• 2013

As recent buildings have been more higher and larger, construction vertical lifting planning and operation is a key factor for successful project in tall building. Although many studies have been trying to set up a construction lifting planning system at early stage, there's not existing a control real-time lift operation control system with respect to during construction stage. Therefore, In this study, we use the sensor device to collect the lift operating data for improvement of lift operation efficiency and develope optimum lift operating system which can perform real-time analysis. Finally, we verify the efficiency of proposed system through comparison between realtime operating data and simulated data using proposing system. In this paper, the proposed system show more efficient moving line compared with previous system. This can contribute to development of unmanned lift system.

• Journal of the Korean Vacuum Society
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• v.20 no.2
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• pp.86-92
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• 2011

The diagnosis studies of the process of chemical vapor deposition were carried out by using in-situ particle monitor (ISPM) and self-plasma optical emission spectroscopy (SPOES). We used the two kinds of equipments such as the silicon plasma enhanced chemical vapor deposition system with silane gas and the borophosphosilicate glass depositon system for monitoring. Using two sensors, we tried to verify the diagnostic and in-situ sensing ability of by-product gases and contaminant particles at the deposition and cleaning steps. The processes were controlled as a function of precess temperature, operating pressure, plasma power, etc. and two sensors were installed at the exhaust line and contiguous with each other. the correlation of data (by-product species and particles) measured by sensors were also investigated.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.17 no.3
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• pp.11-17
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• 2003

In this paper, we implemented 2-wire (data gnd) RS232C serial communication interface by applying the Collision Sensing Multiple Access(CSMA) Protocol. The transmitting and receiving wires of RS232C pert are connected together by the interface circuit forming data wire without hardware modification On two-wired common channel connection simultaneous transmission Don mere than two hosts causes data collision. The collision is detected by loop-back test of transmission data comparing with the fed back data to detect the data distortion. Various models are adopted to reduce the probability of retransmitted data collision and experiments show the performance of each cases. Due to allowing multiple hosts to be accessed through the common communication channel with minimum circuit addition the result of this paper can be easily applied for conventional RS232C instruments and machines to connect to the single data communication line.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.21 no.4
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• pp.143-148
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• 2021

A systematic study of Bloch surface wave (BSW), which is created by guided mode resonance (GMR) of dielectric multilayer structures with a grating profile, is presented to analyze the sensing performance of bio-sensors. The effect of structural parameters on optical behavior is evaluated by using Babinet's principle and modal transmission-line theory. The sensitivity of designed bio-sensors is proportional to the grating constant at wavelength spectrum, and inversely proportional to the normal wave vector of incident electromagnetic wave at angular spectrum. Numerical results for two devices with SiO/SiO₂ and TiO₂/SiO₂ multilayer dielectric stacks are presented, showing that BSW can be exploited for the realization of efficient diffraction-based bio-sensors from infrared to visible-band range.

• Journal of IKEEE
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• v.26 no.2
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• pp.313-318
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• 2022

The feedback voltage detection structure is proposed to alleviate overshoot and undershoot caused by the removal of the existing external output capacitor. Conventional LDO regulators suffer from overshoot and undershoot caused by imbalances in the power supply voltage. Therefore, the proposed LDO is designed to have a more improved transient response to form a new control path while maintaining only the feedback path of the conventional LDO regulator. A new control path detects overshoot and undershoot events in the output stage. Accordingly, the operation speed of the pass element is improved by charging and discharging the current of the gate node of the pass element. LDO regulators with feedback voltage sensing architecture operate over an input voltage range of 3.3V to 4.5V and have a load current of up to 200mA at an output voltage of 3V. According to the simulation result, when the load current is 200mA, it is 73mV under the undershoot condition and 61mV under the overshoot condition.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.22 no.3
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• pp.145-150
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• 2022

An analytical model based on a modal transmission-line theory (MTLT) is developed to investigate the optical transmission through metal gratings. This model gives well physical meanings for the transmission as well as for the dispersion relations of the modes responsible for high transmission. These concepts provide accurate information even for real metals used in the visible~near-infrared wavelength range, where surface plasmon polaritons (SPP's) are excited. Furthermore, the dispersion relations allow the nature of the propagation modes to be assessed. The propagation modes are hybrid between Fabry-Pérot like modes and SPP's. It is important to consider different period and aspect ratio of metal gratings in order to determine the nature of the hybrid modes. In this paper, the sensing characteristics and mode propagation phenomena of high-performance plasma bio-sensors that depend on these variables were clearly analyzed.

• Korean Journal of Remote Sensing
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• v.24 no.6
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• pp.551-558
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• 2008

It is well known that the protein content of rice grain is an indicator of taste of cooked rice in the countries where people as the staple food. Ground-based optical sensing over the crop canopy would provide information not only on the mass of plant body which reflects the light, but also on the crop nitrogen content which is closely related to the greenness of plant leaves. The vegetation index has been related to crop variables such as biomass, leaf nitrogen, plant cover, and chlorophyll in cereals. The objective of this study was to investigate the correlation between GNDVI and NDVI values, and grain protein content at different dates and to estimate the grain protein content using G(NDVI) values. We measured Green normalized difference vegetation index [$GNDVI=({\rho}0.80{\mu}m-{\rho}0.55{\mu}m)/({\rho}0.80{\mu}m+{\rho}0.55{\mu}m)$] and [$GNDVI=({\rho}0.80{\mu}m-{\rho}0.68{\mu}m)/({\rho}0.80{\mu}m+{\rho}0.68{\mu}m)$] by using two different active sensors. The study was conducted during the rice growing season for three years from 2005 through 2007 at the experimental plots of National Institute of Agricultural Science and Technology. The experiments were carried out by randomized complete block design with the application of four levels of nitrogen fertilizers(0, 70, 100, 130kg N/ha) and the same amount of phosphorous and potassium content of the fertilizers. After heading stage, relationships between GNDVI of rice canopy and grain protein content showed the highly positive correlation at different dates for three years. GNDVI values showed higher correlation coefficients than that of NDVI during growing season in 2005-07. The correlation between GNDVI values at different dates and grain protein contents was highly correlated at early July. We attempted to estimate the grain protein content at harvesting stage using GNDVI values from early July for three years. The determination coefficients of the linear model by GNDVI values were 0.9l and the measured and estimated grain protein content at harvesting stage using GNDVI values highly correlated($R^2=0.96^{***}$). Results from this study show that GNDVI appeared very effective to estimate leaf nitrogen and grain protein content of rice canopy.