• Journal of the Korean Society of Groundwater Environment
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• v.1 no.2
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• pp.90-99
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• 1994

Heterogeneous hydraulic conductivity in a flow domain is generated under the assumption that it is a random variable with a lognormal, spatially-correlated distribution. The hydraulic head and the conductivity in a groundwater flow system are represented as a stochastic process. The method of Monte Carlo Simulation (MCS) and the finite element method (FEM) are used to determine the statistics of the head and the logconductivity. The second moments of the head and the logconductivity indicate that the cross-covariance of the logconductivity with the head has characteristic distribution patterns depending on the properties of sources, boundary conditions, head gradients, and correlation scales. The negative cross-correlation outlines a weak-response zone where the flow system is weakly responding to a stress change in the flow domain. The stochastic approach has a potential to quantitatively delineate the zone of influence through computations of the cross-covariance distribution.

• Journal of the Optical Society of Korea
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• v.12 no.2
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• pp.98-102
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• 2008

Optical Coherence Tomography (OCT) is an important noninvasive medical imaging technique that can reveal subsurface structures of biological tissue. OCT has demonstrated a good correlation with histology in sufficient resolution to identify morphological changes in articular cartilage to differentiate normal through progressive stages of degenerative joint disease. Current OCT systems provide individual cross-sectional images that are representative of the tissue directly under the scanning beam, but they may not fully demonstrate the degree of degeneration occurring within a region of a joint surface. For a full understanding of the nature and degree of cartilage degeneration within a joint, multiple OCT images must be obtained and an overall assessment of the joint surmised from multiple individual images. This study presents frequency domain three-dimensional (3-D) OCT imaging of degenerative joint cartilage extracted from bovine knees. The 3-D OCT imaging of articular cartilage enables the assembly of 126 individual, adjacent, rapid scanned OCT images into a full 3-D image representation of the tissue scanned, or these may be viewed in a progression of successive individual two-dimensional (2-D) OCT images arranged in 3-D orientation. A fiber-based frequency domain OCT system that provides cross-sectional images was used to acquire 126 successive adjacent images for a sample volume of $6{\times}3.2{\times}2.5\;mm^3$. The axial resolution was $8\;{\mu}m$ in air. The 3-D OCT was able to demonstrate surface topography and subsurface disruption of articular cartilage consistent with the gross image as well as with histological cross-sections of the specimen. The 3-D OCT volumetric imaging of articular cartilage provides an enhanced appreciation and better understanding of regional degenerative joint disease than may be realized by individual 2-D OCT sectional images.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.9 no.5
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• pp.698-707
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• 1998

For inverse scattering problems reconstructing cross-sectional permittivity distributions of dielectric cylinders, the angular spectral inverse technique using the moment method with pulse basis function suffers from large reconstruction error even if very small noise due to requiring the higher spectral informations on the larger cross-section of the cylinder. To reduce the number of higher-order spectra, this paper presents an improved inverse technique in angular spectral domain applying the moment procedure with a series-expansion basis function for the induced field in each enlarged cross-sectional cell. By choosing adequate spectra and averaging over the enlarged cells with a suitable weighting function, the reconstruction profiles reveal fine enough to suppress the noise effect significantly.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.12 s.354
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• pp.83-88
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• 2006

In this paper, we propose a new cross bar embedded structure for improvement of attenuation characteristics along the different lossy media. A general characterization procedure based on the extraction of the characteristic impedance and propagation constant for analyzing a single MIS(Metal-Insulator-Semiconductor) transmission line used and an analysis for a new substrate shielding MIS structure consisting of grounded crossbars at the interface between Si and Sio2 layer using the Finite-Difference Time-Domain(FDTD) technique is used. In order to reduce the substrate effects on the transmission line characteristics, a shielding structure consisting of grounded cross bar lines over time-domain signal has been examined. The extracted, distributed frequency-dependent transmission line parameters as well as the line voltages and currents, and also corresponding equivalent circuit parameters have been examined as function of frequency. It is shown that the quality factor of the transmission line can be improved without significant changes in the characteristic impedance and effective dielectric constant.

• Journal of Society of Preventive Korean Medicine
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• v.26 no.1
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• pp.59-74
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• 2022

Objectives : Evidence supporting the cold-heat symptom and sasang constitution type, which are diagnostic items of traditional Korean medicine, is needed to manage sleep disturbances, which is a typical symptom of mibyeong (subhealth). This study examined the association between each cold-heat symptom and sleep disturbances according to each sasang constitution type. Methods : This research was a cross-sectional study of 5,793 subjects from the Korean Medicine Data Center (KDC) community cohort survey. The association between each cold-heat symptom and sleep disturbances was analyzed by logistic regression analysis adjusted for several demographic variables. Subgroup analysis was then performed for each type of sasang constitution. Results : The soeum and soyang types were 1.53 and 1.26 times more likely to have sleep disturbances than the taeum type. Sleep disturbances were associated with 'coldness of the abdomen', 'watery mouth' in the cold domain items, and 'body feverishness', 'flushed face and eye', 'thirst', and 'scanty dark urine' in the heat domain items. The soeum and soyang types were 1.55 and 1.39 times more likely to sleep less than five hours per night than the taeeum type. In addition, the associations of those showed a different pattern for each sasang constitution type. Conclusions : Sleep disturbances are associated with specific cold-heat symptoms, and the associated cold-heat symptoms differ according to the sasang constitution type. These results may help traditional medicine specialists select customized interventions for patients with sleep disturbances.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.10
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• pp.1648-1654
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• 2016

This paper analyzes complex vector current control for the enhanced cross-coupling compensation in accordance with parameter variation in grid-connected inverter system, and verifies through simulation and experiment. Complex vector current control is performed in the synchronous reference frame through d-q transformation. It generates cross-coupling components with rotating nominal angular frequency. In general, cross-coupling elements are compensated by decoupling terms added to output of conventional decoupling PI controller. But, it is impossible to compensate them perfectly which transient response is especially deteriorated such as large overshoot and slow tracking, when variation of grid impedance or measurement error occurs. However, complex vector current control can improve stability and response characteristic of current control regardless of the situation as before. Decoupling controller and complex vector controller are represented through complex forms, and these controllers are analyzed by using frequency response in s-domain, respectively. It is verified that complex vector controller has more superior response characteristic than decoupling controller through MATALB, PSIM and experimental in 5kW grid-connected inverter when L filter parameter is varied from 1.1mH to increase double, 2.2mH.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.289-294
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• 2002

In this study, performance, flow characteristics and noise of a cross-flow-fan system, used in indoor unit of the split-type air conditioner, were predicted by computational simulation. Triangular elements were used to mesh the calculation domain and quadrilateral elements were attached to the blade surfaces and walls to enhance the simulation quality. The unsteady incompressible Wavier-Stokes equations were solved using a sliding mesh technique on the interface between rotating fan region and the outside. Two stripes of velocity stream inside the cross-flow-fan were shown - the one was due to the eccentric vortex and the other was due to the normal entrance flow. As the flow rate increased, the center of the eccentric vortex moved toward the inner blade tip and rear-guide, and the exiting flow still had velocity variation along the stabilizer, which can increase the noise level. The acoustic pressure was calculated by using Lowson's equation. From the calculated acoustic pressure, it was found that the trailing edge is a dominant of acoustic generation.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.3
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• pp.225-236
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• 2002

In this paper, to counteract a cross-polarization interference caused by co-channel dual polarization technique of digital radio relay system(DRRS), we analyze the theoretical model and digital design of cross-polarization interference canceller(XPIC). In addition a complex adaptive time domain equalizer(ATDE) is designed using a finite impulse response filter, and the structure of XPIC and its control method are also illustrated including ATDE. Our computer simulation shows that about 25 dB signature and more than 23 dB XPIC improvement factor can be obtained with XPIC and ATDE. In order to verify the operation of designed XPIC, we review the simulated results in view of tap number, algorithm convergence, system signature, and XPlC improvement factor in connection with 64-QAM DRRS with co-channel dual polarization.

• Journal of Korea Society of Digital Industry and Information Management
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• v.19 no.4
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• pp.147-154
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• 2023

With the recent popularity of smartphones, many games are being developed on mobile-based platforms. As a result, it has brought about many changes in the way mobile game is developed. Especially mobile platforms, which are divided into Android and IOS, can now be applied to each platform without additional development through cross-platform. This means that it is necessary to move away from the method of developing each using separate development tools and implement the development process through cross-platform unique features. In this paper, we studied various methods to increase the productivity and quality of game development for the development of mobile games, and a formal framework considering the development process was developed. The framework consists of process, development domain, and platform support parts, each playing its own role. Items of the detailed framework must be reflected so that detailed response data for efficient application of game development can be established in actual mobile game development. The framework was developed by approaching it from two domains, the need for a framework and the framework implementation of key item response data.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.42 no.4 s.304
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• pp.159-166
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• 2005

This thesis deals with a method to deliver more realistic sound by cancelling the cross-talk which is inherent to the 5.1 channel speaker system. First, the cross-talk cancellation method that eliminates cross-talks on the path from left speaker to right ear and from right speaker to left ear is explained. Then the application and replaying method using the cross-talk cancellation explained here is introduced. The acoustical model for cross-talk cancellation is the free field model This model minimizes distortion of sound. Many experts also make studies on this model. I used the bark scale sound quality compensation based on psycho-acoustic. For the surround channels, band-limited sound quality compensation is performed in the frequency domain.