• Journal of Internet Computing and Services
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• v.19 no.5
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• pp.43-54
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• 2018

Images taken in haze weather are characteristic of low contrast and poor visibility. The process of reconstructing clear-weather image from a hazy image is called dehazing. The main challenge of image dehazing is to estimate the transmission map or depth map for an input hazy image. In this paper, we propose a single image dehazing method by utilizing the Generative Adversarial Network(GAN) for accurate depth map estimation. The proposed GAN model is trained to learn a nonlinear mapping between the input hazy image and corresponding depth map. With the trained model, first the depth map of the input hazy image is estimated and used to compute the transmission map. Then a guided filter is utilized to preserve the important edge information of the hazy image, thus obtaining a refined transmission map. Finally, the haze-free image is recovered via atmospheric scattering model. Although the proposed GAN model is trained on synthetic indoor images, it can be applied to real hazy images. The experimental results demonstrate that the proposed method achieves superior dehazing results against the state-of-the-art algorithms on both the real hazy images and the synthetic hazy images, in terms of quantitative performance and visual performance.

• Korean Journal of Soil Science and Fertilizer
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• v.38 no.4
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• pp.222-229
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• 2005

A simplified one-dimensional model STELLA was used to predict soil water movement in lllinois corn fields using soil water balance sheets. It offered the potential to increase understanding of soil nitrate and agrochemical leaching process. The model accounted for aU possible annual inputs and outputs of water from a closed ecosystem as represented by corn fields. Water inputs included precipitation, while outputs included runoff, transpiration, evaporation and drainage. To run the model required daily inputs of two climatic data measurements such as daily precipitation and pan evaporation. Vertical water flow through the soil profile was calculated with first order equation including the difference in hydraulic conductivity and matric potential at the various soil types. The output results included daily changes of water content in the soil layers and daily amount of water losses including run-off, percolation, transpiration. This model was verified using Illinois corn field data for the soil water content measured by neutron scattering methods through 1992 to 1994 growing seasons. Approximately 22 to 78% of simulated water contents agreed with the measured values and their standard deviation, depending on soil types, whereas 30 to 70% of simulated water values agreed with the measured values and their standard deviations depending on soil layers.

• Geophysics and Geophysical Exploration
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• v.1 no.1
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• pp.49-56
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• 1998

Seismic tomography has been widely used as high resolution subsurface imaging techniques in engineering applications. Although most of the techniques have been using travel time inversion, waveform method is being driven forward owing to the progress of computational environments. Although full-waveform inversion method has been known as the best method in terms of model resolving power without high-frequency restriction and weak scattering approximation, it has practical disadvantage that it is apt to get stuck in local minimum if the initial guess is far from the actual model and it consumes so much time to calculate. In this study, 2-D full-waveform inversion algorithm in acoustic medium is developed, which uses result of traveltime tomography as initial model. From the application on synthetic data, it is proved that this approach can efficiently reduce the problem of conventional approaches: our algorithm shows much faster convergence rate and improvement of model resolution. Result of application on physical modeling data also shows much improvement. It is expected that this algorithm can be applicable to real data.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.36 no.4
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• pp.129-137
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• 2024

An analytic solution for the interaction between an array of circular piles made by joining trapezoid steel pipes (TSP) and waves was obtained using an eigenfunction expansion method. First, an analytic model for the wave scattering of multiple piles fixed at arbitrary positions was derived, and then a simplified model was obtained assuming that an infinite array of identical piles were deployed perpendicular to the propagating direc- tion of incident waves. A regular wave experiment was conducted using an experimental model with a scale ratio of 1/100 in a two-dimensional wave tank to verify the analytic solutions. The analytic results and experimental results were qualitatively consistent with each other. Using a developed analytic model, we examined the wave force on the multiple piles and the wave deformation in front of the arrayed piles. The period for the installation is greatly reduced as the TSP pile can be prefabricated in a factory. In particular, it is possible to install at the soft seabed. A seawall structure using arrayed TSP piles will be an ideal complement for a concrete seawall in future.

• Progress in Medical Physics
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• v.13 no.1
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• pp.21-26
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• 2002

A practical calculation algorithm which calculates the relative output factor(ROF) for irregular shaped electron field has been developed and evaluated the accuracy of the algorithm. The algorithm adapted two-source model, which assumes that the electron dose can be express as sum of the primary source component and the scattered component from the shielding block. Original two-source model has been modified in order to make the algorithm simpler and to reduce the number of parameters needed in the calculation, while the calculation error remains within clinical tolerance range. The primary source is assumed to have Gaussian distribution, while the scattered component follows the inverse square law. Depth and angular dependency of the primary and the scattered are ignored ROF can be calculated with three parameters such as, the effective source distance, the variance of primary source, and the scattering power of the block. The coefficients are obtained from the square shaped-block measurements and the algorithm is confirmed from the rectangular or irregular shaped-fields used in the clinic. The results showed less than 1.0 ％ difference between the calculation and measurements for most cases. None of cases which have bigger than 2.1 ％ have been found. By improving the algorithm for the aperture region which shows the largest error, the algorithm could be practically used in the clinic, since one can acquire the 1011 parameter's with minimum measurements(5∼6 measurements per cones) and generates accurate results within the clinically acceptable range.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.12 no.4
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• pp.425-433
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• 2019

In this paper, the RCS analysis of the 10m unmanned surface vehicles was performed, and the factors of RCS increase were analyzed. Modeling techniques by transforming a geometric shape can reduce the RCS area, which can be used to develop stealth unmanned surface vehicles. In order to reduce the RCS, the existing Top Mast part was moved 1m to the tail part, the 5 degree tilt angle was moved below 0.5 m, and additional guided walls were installed to minimize the influence on the center and surrounding corner reflecting structures. As a result of comparing and analyzing the RCS analysis value with the existing model, it can be seen that the reduced countermeasure model is -3.79 dB lower than the existing model for all elevations. In particular, it can be seen that the strong scattering phenomenon is substantially removed in the region except the sacrificial angle region. In addition, it can be seen that in the case of -5m to 2m where the guide wall is added, the reflected signal is improved up to 20 to 40 dB or more, so that it does not appear on the 2D ISAR image. RCS analysis of unmanned surface vehicles explained the process of analyzing and identifying problem location through distance profile analysis and ISAR image analysis.

• Journal of Environmental Science International
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• v.17 no.6
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• pp.623-631
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• 2008

Many recent studies have concentrated upon the radiative effects of atmospheric aerosols. Though their scattering and absorption of radiation, aerosols can also induce some other important environment effects. In this study, new radiation code and aerosol data within Atmosphere General Circulation Model (AGCM) is used to assess the aerosol radiative forcing and to analyze relative climate effects. The new Kangnung National University AGCM Stratospheric-15 (KNU AGCM ST15) was integrated by using two sets of radiative effect of aerosols: CTRL as not a radiative effect of aerosols and AERO as a radiative effect of aerosols. Two cases show the difference of net shortwave radiation budget at top-of-atmosphere (TOA) is found to be about $-3.4Wm^{-2}$, at the surface (SFC) is about $-5.6Wm^{-2}$. Consequently the mean atmospheric absorption due to aerosol layer in global is about $2.2Wm^{-2}$. This result confirms the existence of a negative forcing due to the direct effect of aerosols at the surface and TOA in global annual mean. In addition, it is found that cooling over at the surface air temperature due to radiative effect of aerosols is about $0.17^{\circ}C$. It is estimated that radiative forcing of the net upward longwave radiation taken as the indirect effect of aerosol is much smaller than that of the direct effect as there is about $0.2Wm^{-2}$ of positive forcing both at TOA and at SFC. From this study, It made an accurate estimation of considering effect of aerosols that is negative effect. This may slow the rate of projected global warming during the $21^{st}$ century.

• Asian Journal of Atmospheric Environment
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• v.6 no.2
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• pp.96-103
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• 2012

Ambient particulate matter (PM) and particle-bound polycyclic aromatic hydrocarbon (PAH) concentrations were measured continuously for 70 days at a Korean elementary school located near a highway. The $PM_{10}$, $PM_{2.5}$, and $PM_1$ values were measured with a light-scattering, multi-channel, aerosol spectrometer (Grimm, Model 1.107). The number concentrations of the particles were measured using a scanning mobility particle sizer and counter (SMPS+C) which counted particles from 11.1 to 1083.3 nm classified in 44 channels. Particle-bound PAHs were measured with a direct reading, photoelectric aerosol sensor. The daily $NO_2$, $SO_2$, and CO concentrations were obtained from a national air-monitoring station located near the school. The average concentrations of $PM_{10}$, $PM_{2.5}$, and $PM_1$ were 75.3, 59.3, and $52.1{\mu}g/m^3$, respectively. The average number concentration of the ultrafine particles (UFPs) was $46,307/cm^3$, and the averaged particle-bound PAHs concentration was $17.9ng/cm^3$ during the study period. The ambient UFP variation was strongly associated with traffic intensity, particularly peak concentrations during the traffic rush hours. Particles <100 nm corresponded to traffic-related pollutants, including PAHs. Additional longterm monitoring of ambient UFPs and high-resolution traffic measurements should be carried out in future studies. In addition, transient variations in the ambient particle concentration should be taken into consideration in epidemiology studies in order to examine the short-term health effects of urban UFPs.

• Aerospace Engineering and Technology
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• v.13 no.2
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• pp.80-86
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• 2014

In this study, we the estimated surface normalized difference vegetation index by using the KOrea Multi-Purpose SATellite-3 (KOMPSAT-3) multi-spectral images for comparative analysis. The estimated NDVI from KOMPSAT-3 is used as for comparison with the high resolution GeoEye products. The geometry conditions for atmospheric effects are selected from meta files of KOMPSAT-3 bundle data. The used geometry conditions are consist of solar zenith angle, solar azimuth angle, viewing zenith angle, viewing azimuth angle, and date. And, Atmospheric effects such as attenuation, scattering and absorption were physically simulated from water vapor, ozone and aerosol information. Generally, although ground measurements are important for accurate information, in this study, MODIS atmospheric products are used as atmospheric constituents. The surface reflectance from radiative transfer model is utilized for estimating vegetation index. The present study, to reduce atmospheric and geometry conditions between KOMPSAT-3 and GeoEye having difference observation characteristics, data acquisition time is carefully determined for reliable vegetation spectral characteristics.

• Bulletin of the Korean Chemical Society
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• v.34 no.6
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• pp.1800-1808
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• 2013

Dual-responsive amphiphilic block copolymers were synthesized by combining enzymatic ring-opening polymerization (eROP) of ${\varepsilon}$-caprolactone (CL) and ATRP of N,N-dimethylamino-2-ethyl methacrylate (DMAEMA). The obtained block copolymers were characterized by gel permeation chromatography (GPC), $^1H$ NMR and FTIR-IR. The critical micelle concentration (CMC) of copolymer was determined by fluorescence spectra, it can be found that with hydrophilic block (PDMAEMA) increasing, CMC value of the polymer sample increased accordingly, and the CMC value was 0.012 mg/mL, 0.025 mg/mL and 0.037 mg/mL for $PCL_{50}$-b-$PDMAEMA_{68}$, $PCL_{50}$-b-$PDMAEMA_{89}$, $PCL_{50}$-b-$PDMAEMA_{112}$, $PCL_{50}$-b-$PDMAEMA_{89}$ was chosen as drug carrier to study in vitro release profile of anti-cancer drug (taxol). The temperature and pH dependence of the values of hydrodynamic diameter (Dh) of micelles, and self-assembly of the resulting block copolymers in water were evaluated by dynamic light scattering (DLS). The result showed that with the temperature increasing and pH decreasing, the Dh decreased. Drug-loaded nanoparticles were fabricated using paclitaxel as model. Transmission electron microscopy (TEM) and atomic force microscopy (AFM) had been explored to study the morphology of the hollow micelles and the nanoparticles, revealing well-dispersed spheres with the average diameters both around 80 nm. In vitro release kinetics of paclitaxel from the nanoparticles was also investigated in different conditions (pH and temperature, etc.), revealing that the drug release was triggered by temperature changes upon the lower critical solution temperature (LCST) at pH 7.4, and at $37^{\circ}C$ by an increase of pH.