• Korean Journal of Optics and Photonics
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• 제14권5호
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• pp.483-490
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• 2003

We have analyzed theoretically optical pulse propagation in a coherent atomic medium for amplification without inversion (AWI), which is achieved by adding incoherent optical pumping to a typical EIT system. In order to explain experimental results [Kim et al., J. Phys. B, 36, 2671(2003)] to control the group velocity of the optical pulse by changing pumping power, we established a 5-level atomic system and applied density matrix equations. This AWI model system is different from previous AWI systems from the viewpoint of using two levels for incoherent optical pumping isolated optically from the EIT (electromagentically induced transparency) system so that more atoms can participate in pulse speed control. We have found that population transfer by collisions between ground states plays a decisive role for efficient AWI, and more atoms are effective for slowing the pulse. Our numerical results are in good agreement qualitatively with experimental results.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• 제18권6호
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• pp.137-154
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• 2019

This study analysed the center control emergency vehicle preemption[EVP] test result on the 1.782 km section around Gangbuk Fire Station. The pros and cons between center control and site control EVP was compared through the review of existing research. The test site was selected based on the higher link speed for choosing low congested area and 4 to 6 lane road. EVP operates green extension under the estimated arrival time to each intersection. This study is about EVP system field application and its evaluation by analyzing EVP operation result with the emergency vehicle's trace, GPS data. The impact on the surrounding traffic was analysed in delay from the queue length survey. Analysis showed the decrease in averge travel time 41.81%, but the increase in delay of surrounding traffic slightly. It is expected that EVP can be applied to the expanded area by researching EVP compensation scheme.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• 제30권6_1호
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• pp.575-581
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• 2012

In general, various modeling and estimation techniques have been proposed to extract the tropospheric and ionospheric delays from the GPS CORS. In this study, Kalman filter approach is adopted to estimate the tropospheric and ionospheric delays and the proper modeling for the state vector and the variance-covariance matrix for the process noises are performed. The coordinates of reference stations and the zenith wet delays are estimated with the assumption of random walk stochastic process. Also, the first-order Gauss-Markov stochastic process is applied to compute the ionospheric effects. For the evaluation of the proposed modeling technique, Kalman filter algorithm is implemented and the numerical test is performed with the CORS data. The results show that the atmospheric effects can be estimated successfully and, as a consequence, can be used for the generation of VRS data.

• Journal of the Korean Geotechnical Society
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• 제28권4호
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• pp.67-78
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• 2012

A three-dimensional approximate computer-based method, YSPR (Yonsei Piled Raft), was developed for analysis of behavior of piled raft foundations. The raft was modeled as a flat shell element having 6 degrees of freedom at each node and the pile was modeled as a beam-column element. The behaviors of pile head and soil were controlled by using $6{\times}6$ stiffness matrix. To model the non-linear behavior, the soil-structure interaction between soil and pile was modeled by using nonlinear load-transfer curves (t-z, q-z and p-y curves). Comparison with previous model and FEM analysis showed that YSPR gave similar load-displacement behaviors. Comparison with field measurement also indicated that YSPR gave a reasonable result. It was concluded that YSPR could be effectively used in analysis and design of piled raft foundations.

• Journal of the Korea Society of Computer and Information
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• 제10권1호
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• pp.59-66
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• 2005

The organization of the web is progressively more being used to improve search and analysis of information on the web as a large collection of heterogeneous documents. Most people begin at a Web search engine to find information. but the user's pertinent search results are often greatly diluted by irrelevant data or sometimes appear on target but still mislead the user in an unwanted direction. One of the intentional, sometimes vicious manipulations of Web databases is a intentionally biased web page like Google bombing that is based on the PageRank algorithm. one of many Web structuring techniques. In this thesis, we regard the World Wide Web as a directed labeled graph that Web pages represent nodes and link edges. In the Present work, we define the label of an edge as having a link context and a similarity measure between link context and target page. With this similarity, we can modify the transition matrix of the PageRank algorithm. By suggesting a motivating example, it is explained how our proposed algorithm can filter the Web intentionally biased web Pages effective about $60\%% rather than the conventional PageRank.

• Journal of KIISE:Computer Systems and Theory
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• 제30권7_8호
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• pp.359-369
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• 2003

We present efficient generalized algorithms for all-to-all personalized communication operations in a 2D torus. All-to-all personalized communication, or complete exchange, is at the heart of numerous applications, such as matrix transposition, Fast Fourier Transform(FFT), and distributed table lookup. Some algorithms have been Presented when the number of nodes is power-of-2 or multiple-of-four form, but there has been no result for general cases yet. We first present complete exchange algorithm called multiple-Hop-2D when the number of nodes is in the form of multiple-of-two. Then by extending this algorithm, we present two algorithms for an arbitrary number of nodes. Split-and-Merge algorithm first splits the whole network into zones. After each zone performs complete exchange, merge is applied to finish the desired complete exchange. By handling extra steps in Double-Hop-2D algorithm, Modified Double-Hop-2D algorithm performs complete exchange operation for general cases. Finally, we compare the required start-up time for these algorithms.

• The Journal of the Korea institute of electronic communication sciences
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• 제14권2호
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• pp.439-446
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• 2019

In this paper, we propose a encryption method using C-MLCA and 1D CAT to secure medical image for efficiently. First, we generate a state transition matrix using a Wolfram rule and create a sequence of maximum length. By operating the complemented vector, it converts an existing sequence to a more complex sequence. Then, we multiply the two sequences by rows and columns to generate C-MLCA basis images of the original image size and go through a XOR operation. Finally, we will get the encrypted image to operate the 1D CAT basis function created by setting the gateway values and the image which is calculated by transform coefficients. By comparing the encrypted image with the original image, we evaluate to analyze the histogram and PSNR. Also, by analyzing NPCR and key space, we confirmed that the proposed encryption method has a high level of stability and security.

• Journal of Preventive Medicine and Public Health
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• 제21권2호
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• pp.329-339
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• 1988

The study is carried out to investigate the effect of drinking and smoking for the activities of aspartate aminotransferase(AST, or GOT) and alanine aminotransferase(ALT or GPT), from December 25, 1986 to April 30, 1987. The male physical examinees for employment, 900 who had visited to the Taegu Medical Center were subjected. And the positive cases of HBs-Ag, Anti-HBs and skin test for Clonorchis sinensis were excluded. The general characters of drinking and smoking pattern were introduced by interview with questionnaire provided for. In drinking cases, the longer duration was significantly effected the higher rate of abnormality in AST and ALT level. But the amount and the frequency were not. It was not appeared effects by mackgulri which is a Korean traditional wine and small amount of beers. In smoking cases, also same pattern. The age was related in all cases. By the way, when the effect is related the positive results with other factors: HBs-Ag, Anti-HBs, skin test for Clonorchiasis and harmful occupational history, it is higher abnormal rate of AST and ALT in the duplicated cases with two factors or more. Particularly in HBs-Ag positive cases, those who had smoking was the highest in rate of abnormality, and drinking was the follows. In correlation matrix among seven factors; HBs-Ag, age, drinking amount, drinking period, drinking frequency, smoking amount and smoking period, correlation coefficient was significant between the abnormal rate and to with age, drinking period, smoking period, and smoking amount.

• The Journal of the Acoustical Society of Korea
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• 제19권3호
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• pp.35-44
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• 2000

In this paper, we propose a new trajectory model for characterizing segmental features and their interaction based upon a general framework of hidden Markov models. Each segment, a sequence of vectors, is represented by a trajectory of observed sequences. This trajectory is obtained by applying a new design matrix which includes transitional information on contiguous frames, and is characterized as a polynomial regression function. To apply the trajectory to the segmental HMM, the frame features are replaced with the trajectory of a given segment. We also propose the likelihood of a given segment and the estimation of trajectory parameters. The obervation probability of a given segment is represented as the relation between the segment likelihood and the estimation error of the trajectories. The estimation error of a trajectory is considered as the weight of the likelihood of a given segment in a state. This weight represents the probability of how well the corresponding trajectory characterize the segment. The proposed model can be regarded as a generalization of a conventional HMM and a parametric trajectory model. The experimental results are reported on the TIMIT corpus and performance is show to improve significantly over that of the conventional HMM.

• Korean Journal of Optics and Photonics
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• 제9권2호
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• pp.111-116
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• 1998

Thirteen InGaAs/InGaAsP separate-confinement heterostructure multiple quantum well lasers were designed such that the strain in the active layer from 0.9% compressive strain to 1.4% tensile, and their threshold current density was caluculated to see the effects of strain on the threshold current density. The well width was adjusted such that the bandgap of the quantum well is 1.55 ${\mu}{\textrm}{m}$, For the calculation of the band structure and transition matrix element needed for the gain calculation, a block diagonalized 8$\times$8 second-order $\to{k}.\to{p}$ Hamiltonian was used to incorporate the conduction band nonparabolicity and the valence band mixing. The threshold current density shows discontinuity at 0.4% tensile strain where the first heavy-hole subband and the first light-hole subband cross and at 0.5% tensile strain where the second conduction subband begins to exist. The threshold current density at room temperature has a maximum around these 0.4-0.5% tensile strains, and as strain varies in either direction it decreases first and then increases a little after a local minimum. This calculated trend is consistent with the other reported experimental results. We discussed the results of this calculation in comparison with other theoretical or experimental papers on the effect of strain.