• Korean Journal of Optics and Photonics
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• v.35 no.1
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• pp.1-8
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• 2024

Explicit expressions for the transmission pseudo-ellipsometric constants and transmittance of a semi-transparent glass substrate coated with thin films are presented to determine the optical constants of a very weakly absorbing thin film coated on a glass substrate. The intensity of the multiply reflected light inside the semi-transparent substrate is superposed incoherently and the light absorption by the substrate is properly treated, so that modeling analysis of thin films coated on a semi-transparent substrate can be performed with increased accuracy. The extinction coefficient derived from transmittance analysis is compared to that from ellipsometric analysis in the weakly absorbing region, and the difference between the two extinction coefficients is discussed in relation to the sensitivities of the transmittance and ellipsometric constants. This transmittance analysis, together with ellipsometric analysis, is applied to a glass substrate coated with a SiN thin film, and it is shown that the thickness and complex refractive index of the SiN thin film can be determined accurately, even though the extinction coefficient is very small.

• The Journal of the Korea institute of electronic communication sciences
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• v.5 no.4
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• pp.357-362
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• 2010

This paper proposes the speech and noise recognition system by using a neural network in order to detect the speech and noise sections at each frame. The proposed neural network consists of a layered neural network training by back-propagation algorithm. First, a power spectrum obtained by fast Fourier transform and linear predictive coefficients are used as the input to the neural network for each frame, then the neural network is trained using these power spectrum and linear predictive coefficients. Therefore, the proposed neural network can train using clean speech and noise. The performance of the proposed recognition system was evaluated based on the recognition rate using various speeches and white, printer, road, and car noises. In this experiment, the recognition rates were 92% or more for such speech and noise when training data and evaluation data were the different.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.44 no.3
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• pp.81-89
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• 2007

This paper presents a parallel distributed implementation of the GHT (generalized Hough transform) for the fast processing on the MPI-based PC cluster. We tried to achieve the higher speedup mainly by alleviating the communication overhead through the pipelined broadcast and accumulator array partition strategy and by time overlapping of the communication and the computation over entire process. Experimental results show that nearly linear speedup is reachable by the proposed method on the MPI-based PC clusters connected through 100Mbps Ethernet switch.

• Journal of Korea Water Resources Association
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• v.37 no.9
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• pp.729-736
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• 2004

Analysis of reflection of random waves propagating over rectangular submerged non-porous breakwaters was performed by using the eigenfunction expansion method. In this study, random waves were generated by superposition of several monochromatioc waves. Reflection coefficients were calculated by summing each numerical results of regular waves. Predicted results from the eigenfunction expansion method were in a good agreement with the results of laboratory measurements. Reflection coefficients of random waves were also resonated at the Bragg reflection condition.

• Journal of Korea Water Resources Association
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• v.52 no.7
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• pp.483-492
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• 2019

An analytical model was developed to estimate the stream depletion due to cyclic groundwater pumping by extending the Hunt's analytical solution which was derived from considering the hydraulic characteristics of the aquifer and the streambed. The model was applied to analyze the long-term effects of groundwater pumping on stream depletion during irrigation season. For the case of a total of 1,500 conditions according to various aquifer and streambed hydraulic characteristics and stream-well distance, the stream depletion due to cyclic groundwater pumping for 10 years was calculated and the results were graphically represented. Especially, the maximum and average stream depletion rates were calculated and compared with the results for continuous groundwater pumping. Furthermore, considering both stream depletion and return flow rates, the limit hydraulic condition that minimizes the influence of groundwater pumping for irrigation water supply on stream depletion was suggested.

• Spatial Information Research
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• v.4 no.1
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• pp.93-105
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• 1996

The purpose of this study was to give some ideas to the improving direction and evaluation in order to solve physical' ecological problems appeared after urban park construction. This study selected Namsangol park as a site, because this park was constructed to the goal in order to rehabilitate the original landform as a part of "Namsan original landscape rehabilitation work". So this study was executed to investigate past and present landform change, soil condition, planting, water/climate etc., and then these were analyzed by GIS.- soil :pH, Ec, organic matter, the ability of moisture content, bulk density, porosity, etc.- planting:planting density, plant species- water/climate: the amount of rainfall, drainage and drainage-basin. And then this study overlayed soil+cut/fill, soil+pine tree, cut/fill + planting density, and cut/fill + plant species.t species.

• Journal of KIISE:Databases
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• v.37 no.5
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• pp.275-284
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• 2010

GPUs are stream processors based on multi-cores, which can process large data with a high speed and a large memory bandwidth. Furthermore, GPUs are less expensive than multi-core CPUs. Recently, usage of GPUs in general purpose computing has been wide spread. The CUDA architecture from Nvidia is one of efforts to help developers use GPUs in their application domains. In this paper, we propose techniques to parallelize a skyline algorithm which uses a simple nested loop structure. In order to employ the CUDA programming model, we apply our optimization techniques to make our skyline algorithm fit into the performance restrictions of the CUDA architecture. According to our experimental results, we improve the original skyline algorithm by 80% with our optimization techniques.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.8
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• pp.1537-1545
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• 2016

In real time video sequence, object segmentation and tracking method are actively applied in various application tasks, such as surveillance system, mobile robots, augmented reality. This paper propose a robust object tracking method. The background models are constructed by learning the initial part of each video sequences. After that, the moving objects are detected via object segmentation by using background subtraction method. The region of detected objects are continuously tracked by using the HSV color histogram with particle filter. The proposed segmentation method is superior to average background model in term of moving object detection. In addition, the proposed tracking method provide a continuous tracking result even in the case that multiple objects are existed with similar color, and severe occlusion are occurred with multiple objects. The experiment results provided with 85.9 % of average object overlapping rate and 96.3% of average object tracking rate using two video sequences.

• The Korean Journal of Applied Statistics
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• v.30 no.6
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• pp.943-955
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• 2017

We investigate and estimate the causal effect of the survey methods in telephone surveys for the 19th presidential election. For this causal study, we draw a causal graph that represents the causal relationship between variables. Then we decide which variables should be included in the model and which variables should not be. We explain why the research agency is a should-be variable and the response rate is a shouldnot-be variable. The effect of ARS can not be estimated due to data limitations. We have found that there is no significant difference in the effect of the proportion of cell phone survey if it is less than about 90 percent. But the support rate for Moon Jae-in gets higher if the survey is performed only by cell phones.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.22 no.6
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• pp.565-572
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• 2009

This work intends to establish the reliability and fracture toughness $K_{IC}$ criterion of welded joints by EGW for high strength EH36-TMCP ultra thick plate. For this, firstly thermo elasto-plastic analysis has been carried out on two pass X-groove butt joint model to clarify the thermal and mechanical behaviour(residual stress, plastic strain, magnitude of stress and their distribution and production mechanism). Moreover, to establish fracture criterion, analysis of fracture toughness $K_{IC}$ has been performed under the notch machined and residual stress with the load condition on EGW welded joints. A quantitative fracture criterion for EGW welded joints is suggested by using $K_{IC}$.