• Journal of the Institute of Electronics Engineers of Korea SP
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• v.47 no.6
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• pp.162-170
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• 2010

Adaptive arrays reject interferences while preserving the desired signal, exploiting a priori information on its arrival angle. Subspace-based adaptive arrays, which adjust their weight vectors in the signal subspace, have the advantages of fast convergence and robustness to steering vector errors, as compared with the ones in the full dimensional space. However, the complexity of theses subspace-based methods is high because the eigendecomposition of the covariance matrix is required. In this paper, we present a simple subspace-based method based on the PASTd (projection approximation subspace tracking with deflation). The orignal PASTd algorithm is modified such that eigenvectora are orthogonal to each other. The proposed method allows us to significantly reduce the computational complexity, substantially having the same performance as the beamformer with the direct eigendecomposition. In addition to the simple beamforming method, we present theoretical analyses on the SINR (signal-to-interference plus noise ratio) of subspace beamformers to see their behaviors.

• Journal of the Korean Wood Science and Technology
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• v.33 no.3 s.131
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• pp.64-71
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• 2005

In this study, we attempted to apply ultrasonic treatment for the preservative treatment of two softwood species, Korean pine and Japanese red pines to evaluate its effectiveness. Wood samples were submerged in oilborne preservative, copper naphthenate (NCU) and waterborne preservative, alkyl ammonium compound (AAC) and then treated with ultrasonic wave of 40 kHz, 400 W. After the treatment, the retention and penetration depth of these preservatives in the specimens were measured as a function of treatment time. Both the retention and penetration depth were continuously increased with increasing the treatment time up to 120 hours, where the retention reached about 95% by the application of AAC and the penetrating depth of 95% and 83% by the application of NCU, respectively for both species. The results of electronic microscopic observation showed that the improved retention capacity could be attributed to air deflation, wood extractive deflation working of ultrasonic wavelength, and destruction of wood pits which served as the pathway of preservatives. The results suggested that the use of ultrasonic treatment could be applied to thick wood veneers for the production of laminated wood products.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.9
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• pp.148-156
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• 2014

In the MVDR (minimum variance distortionless response) adaptive array, its performance could be greatly deteriorated in the presence of steering vector errors as the desired signal is treated as an interference. This paper suggests an computationally simple adaptive beamforming method which is robust against these errors. In the proposed method, a minimization problem that is formulated according to the DCB (doubly constrained beamforming) principle is solved to find a solution vector, which is in turn projected onto a subspace to obtain a new steering vector. The minimization problem and the subspace projection are dealt with using some principal eigenpairs, which are obtained using a modified PASTd(projection approximation subspace tracking with deflation). We improve the existing MPASTd(modified PASTd) algorithm such that the computational complexity is reduced. The proposed beamforming method can significantly reduce the complexity as compared with the conventional ones directly eigendecomposing an estimate of the corelation matrix to find all eigenvalues and eigenvectors. Moreover, the proposed method is shown, through simulation, to provide performance improvement over the conventional ones.

• The Korean Journal of Physiology
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• v.17 no.1
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• pp.23-28
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• 1983

In order to clarify the effect of steroid on the pulmonary pressure-volume curve in the pneumonectomized rabbit, the right side pneumonectomy was performed under general anesthesia with pentobarbital sodium and the remaining lung was excised on the fifth day after surgery. The intrapulmonic pressure in the excised left lung was measured at 20, 25, and 30 ml lung volume during inflation and deflation period. In the steroid treated group, the intrapulmonic pressure at 20, 25, and 30 ml lung volume during inflation was significantly decreased compared with intrapulmonic pressure of the control group. But in the pneumonectomy group the decreasing tendency of the pressure was observed. During deflation, the intrapulmonic pressure at 25 ml and 20 ml was not significantly different from the control group in pneumonectomy and steroid treated pneumonectomy group. And the lung weight was measured in each experimental group and also the lung weightbody weight ratio(L/B) was calculated. The lung weight was significantly increased in both pneumonectomy and steroid treated pneumonectomy group. Calculated L/B was increased significantly in both group. Above results suggest that steroid increases the secretion of pulmonary surfactant or affects the catabolic effect on protein metabolism of connective tissue in lung parenchyma.

• Journal of the Korean association of regional geographers
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• v.12 no.4
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• pp.437-448
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• 2006

Bare-topped thufur is called as frost scars, implying the rupturing stage of vegetated mounds, Field observations and measurements provide empirical information on the process and factors of thufur disintegration in Mt. Halla, Initial bare patches on mound apexes are scaled up by continuous removal of soil and vegetation, resulting in the formation of crater-like thufur, Frost action plays a primary role in thufur disintegration, In particular, pipkrake loosens soil particles within the bare patches and subsequently accelerates the degradation of vegetated mounds during periods with frequent diurnal freeze-thaw cycle and high soil moisture, Deflation also has an impact on thufur breakup in that the bare patches usually lack upper dark brown soil and are covered with granules, Withered shrubs such as Juniperus chinensis var. sargentii are frequently observed in frost scars and disrupted mounds, indicating that thufur disintegration has been probably influenced by global warming.

• The Journal of the Acoustical Society of Korea
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• v.20 no.1E
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• pp.7-13
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• 2001

In this paper we propose a new subspace tracking algorithm based on the PASTd (Projection Approximation Subspace Tracking with deflation). The algorithm is obtained via introducing the variable forgetting factor which adapts itself to the time-varying subspace environments. The tracking capability of the proposed algorithm is demonstrated by computer simulations in an abruptly changing DOA scenario. The estimation results of the variable forgetting factor PASTd(VFF-PASTd) outperform those of the PASTd in the nonstationary case as well as in the stationary case.

• Journal of Korean Neurosurgical Society
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• v.41 no.5
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• pp.323-326
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• 2007

Direct carotid-cavernous fistula [CCF] is a common post-traumatic disease. However, pseudoaneurysm formation after balloon occlusion is a rare complication. The author present such a case with review of the literature. A 26-year-old man involved in a motor vehicle accident as a driver. Only mild conjunctival injection and minimal exophthalmos on the right eye were noted after trauma. However, angiography revealed a direct CCF and dissection of the proximal intracranial internal carotid artery [ICA]. After first balloon occlusion of the CCF, the patient redeveloped fistula due to early deflation of the balloon. After the second balloon occlusion, pseudoaneurysm and diplopia were developed with the change of balloon position and shape. However, visual symptom spontaneously resolved and pseudoaneurysm was also decreased within 6 months after balloon occlusion.

• KDI Journal of Economic Policy
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• v.37 no.4
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• pp.21-54
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• 2015

This paper analyzes how and why household debt distribution by the householder age has changed over the past decade both in Korea and the US. Data shows that the proportion of household debt held by younger households has decreased, while that held by older households has increased. Empirical analysis shows that a change in the demographic distribution of householders is the main driving force that has shifted the household debt distribution. Given that demographic aging is an inevitable trend, the proportion of household debt held by older households is also expected to increase. Therefore, the Korean government must preemptively prepare for the household debt problem, especially for debt held by older households, by strengthening macro-prudential policies, preventing asset price deflation, restructuring household debt contract structures, and reforming labor market inflexibility.

• Journal of Communications and Networks
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• v.12 no.3
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• pp.216-221
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• 2010

In this paper, we propose and develop a new algorithm for the principle subspace tracking by orthonormalizing the eigenvectors using an approximation of Gram-Schmidt procedure. We carry out a novel mathematical derivation to show that when this approximated version of Gram-Schmidt procedure is added to a modified form of projection approximation subspace tracking deflation (PASTd) algorithm, the eigenvectors can be orthonormalized within a linear computational complexity. While the PASTd algorithm tries to extracts orthonormalized eigenvectors, the new scheme orthonormalizes the eigenvectors after their extraction, yielding much more tacking efficiency. We apply the new tracking scheme for blind adaptive multiuser detection for non-stationary cellular CDMA environment and use extensive simulation results to demonstrate the performance improvement of the proposed scheme.

• Proceedings of the KIEE Conference
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• 1994.11a
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• pp.78-80
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• 1994

Conventional methods for root finding of the algebraic equations are intrinsically synthetic division methods, i.e., which are the factorization in forms of $f(x)=(x-x_i)Q(x)$. So existing methods have some demerits such as deflation and root-polishing procedures. To overcome these defects a new powerful algorithm, namely circular arithmetic algorithm(CSM), was introduced and has been investigated about its fascinating properties. In this paper, we will propose a simple and effective method of getting the initial guesses for the roots of the equation. With this method the CSM can me all the root of equation with great efficiency.