• The Journal of the Acoustical Society of Korea
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• v.14 no.3
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• pp.71-81
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• 1995

In this paper, feature vector extraction methods and classification algorithms for the automatic classification of transient signals in underwater are discussed. A feature vector extraction method using wavelet transform, which shows good performance with small number of coefficients, is proposed and compared with the existing classical methods. For the automatic classification, artificial neural networks such as multilayer perceptron (MLP), radial basis function (RBF), and MLP-Class are utilized, where those neural networks as well as extracted feature vectors are combined to improve the performance and reliability of the proposed algorithm. It is confirmed by computer simulation with Traco's standard transient data set I and simulated data that the proposed feature vector extraction method and classification algorithm perform well, assuming that the energy of a given transient signal is sufficiently larger than that of a ambient noise, that there are the finite number of noise sources, and that there does not exist noise sources more than two simultaneously.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.12 s.115
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• pp.1224-1230
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• 2006

In this paper, for spatial multiplexing with limited feedback, a precoding scheme is proposed based on the joint use of minimal instantaneous feedback and long-term feedback of a small number of bits, wherein the long-term feedback is used to convey a selected preceding matrix within a precodercodebook consisting of a number of unitary matrices, and the active column vectors of the selected unitary matrix are conveyed to the transmitter using instantaneous feedback. Focusing on the case of dual multi-input multi-output(MIMO) systems, precoder codebook design for maximizing the average throughput of a spatial multiplexing system with a zero-forcing(ZF) receiver is proposed. It is shown that the proposed scheme provides a considerable throughput enhancement over multi-mode antenna selection and multi-mode basis selection only with the additional long-yterm feedback of a small number of bits. For example, the throughput increases by 11.5 % than antenna selection and 5.1% than basis selection, respectively, when SNR=20 dB.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.7C
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• pp.554-564
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• 2012

The vehicle recognition consists of two steps; the vehicle region detection step and the vehicle identification step based on the feature extracted from the detected region. Features using linear transformations have the effect of dimension reduction as well as represent statistical characteristics, and show the robustness in translation and rotation of objects. Among the linear transformations, the NMF(Non-negative Matrix Factorization) is one of part-based representation. Therefore, we can extract NMF features with sparsity and improve the vehicle recognition rate by the representation of local features of a car as a basis vector. In this paper, we propose a feature extraction using NMF suitable for the vehicle recognition, and verify the recognition rate with it. Also, we compared the vehicle recognition rate for the occluded area using the SNMF(sparse NMF) which has basis vectors with constraint and LVQ2 neural network. We showed that the feature through the proposed NMF is robust in the urban scene where occlusions are frequently occur.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.34 no.4
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• pp.199-204
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• 2021

In this study, an isogoemetric analysis (IGA) method that uses NURBS (Non-Uniform Rational B-Spline) basis functions in computer-aided design (CAD) systems is employed to account for the geometric exactness of curved electrodes constituting an electro-adhesive pad in electrostatic problems. The IGA is advantageous for obtaining precise normal vectors when computing the electro-adhesive forces on curved surfaces. By performing parametric studies using numerical examples, we demonstrate the superior performance of the curved electrodes, which is attributed to the increase in the normal component of the electro-adhesive forces. In addition, concave curved electrodes exhibit better performance than their convex counterparts.

• Parasites, Hosts and Diseases
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• v.23 no.2
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• pp.305-312
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• 1985

The surface fine structures of Ixodes persulcatus (Schulze, 1930) male and female specimens were observed by means of a scanning electron microscope. A brief review on the biology of the ticks and their disease relationships was also presented. 1. The sexual dimorphism of the specimen was marked; the male was quite smaller than the female. 2. The genital groove was well developed and deep, the anal groove was distinct and characteristically extending anteriorly around the anus. 3. The 4th article was much reduced and situated on the top of the 3rd article ventrally. The hypostome dentition was usually 3/3. 4. The bottom of the basis capitulum of the male specimen was strictly straight in shape. 5. This species was regarded as one of the most important vectors for infectious diseases of migrating birds.

• Korean Journal of Crystallography
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• v.17 no.1
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• pp.1-5
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• 2006

After the definition of the basis vectors of the two-dimensional direct and reciprocal lattices, various interrelations between them are derived, and additionally how to calculate $\vec{d^*}(hk)//direction\;of\;(hk),\;d(hk)=1/d^*(hk),\;[uv]$, planes belonging to a direction [uv], areas and interplanar spacing of 2-dimensional low different lattices are shown.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.11a
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• pp.561-562
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• 2008

The numerical analysis of sound radiation by vibrating structure is a well known and mature technology used in many industries. Accurate methods based on the boundary or finite element method have been successfully developed over the last two decades and are now available in standard CAE tools. These methods are however known to require significant computational resources which, furthermore, very quickly increase with the frequency of interest. The low speed of most current methods is a main obstacle for a systematic use of acoustic CAE in industrial design processes. In this paper we are going to present a set of innovative techniques that significantly speed-up the calculation of acoustic radiation indicators (acoustic pressure, velocity, intensity and power; contribution vectors). The modeling is based on the well known combination of finite elements and infinite elements but also combines the following ingredients to obtain a very high performance: o a multi-frontal massively parallel sparse direct solver; o a multi-frequency solver based on the Krylov method; o the use of pellicular acoustic modes as a vector basis for representing acoustic excitations; o the numerical evaluation of Green functions related to the specific geometry of the problem under investigation. All these ingredients are embedded in the ACTRAN/AR CAE tool which provides unprecedented performance for acoustic radiation analysis. The method will be demonstrated on several applications taken from various industries.

• Wind and Structures
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• v.9 no.3
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• pp.231-243
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• 2006

An improvement to the spectral representation algorithm for the simulation of wind velocity fields on large scale structures is proposed in this paper. The method proposed by Deodatis (1996) serves as the basis of the improved algorithm. Firstly, an interpolation approximation is introduced to simplify the computation of the lower triangular matrix with the Cholesky decomposition of the cross-spectral density (CSD) matrix, since each element of the triangular matrix varies continuously with the wind spectra frequency. Fast Fourier Transform (FFT) technique is used to further enhance the efficiency of computation. Secondly, as an alternative spectral representation, the vectors of the triangular matrix in the Deodatis formula are replaced using an appropriate number of eigenvectors with the spectral decomposition of the CSD matrix. Lastly, a turbulent wind velocity field through a vertical plane on a long-span bridge (span-wise) is simulated to illustrate the proposed schemes. It is noted that the proposed schemes require less computer memory and are more efficiently simulated than that obtained using the existing traditional method. Furthermore, the reliability of the interpolation approximation in the simulation of wind velocity field is confirmed.

• Structural Engineering and Mechanics
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• v.21 no.5
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• pp.553-570
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• 2005

Dynamic and static analyses of existing structures are very important to obtain reliable information relating to actual structural properties. For this purpose a series of material test, dynamic test and static collapse test of the existing two brick chimneys, in Tokoname, are carried out. From the material tests, Young's modulus and compressive strength of the brick used for these chimneys are estimated to be 3200 MPa and 7.5 MPa, respectively. The results of static collapse test of the existing two brick chimneys are discussed in this paper and composed with the results from FEA (Finite Element analysis). From the results of dynamic tests, the fundamental frequencies of Howa and Iwata brick chimneys are estimated to be about 2.69 Hz and 2.93 Hz, respectively. Their natural modes are identified by ARMAV (Autoregressive Moving Average Vectors) model. On the basis of the static and dynamic experimental tests, a numerical model has been prepared. According to the European code (Eurocode n. 8: "Design of structures for earthquake resistance") non-linear static (Pushover) analysis of the two chimneys is carried out and they seem to be vulnerable to earthquakes with 0.25 to 0.35 g.

• Korean journal of applied entomology
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• v.10 no.2
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• pp.85-89
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• 1971

An investigation was carried out to know the host range of the rice stripe virus as a basis of the disease control. 1. In order to investigate the host range of the rice stripe virus 30 species including gramineaceae and forage crop and weeds were inoculated with viruliferous Laodelphax sriatellus Fallen. As a result, 21 out of 30 species showed typical symptoms. 2. Cyperus amuricus Maximowicz var. laxus., Pycreus sanguinolentus Nees. and Eriocaulon robustius Makino, not belonging to gramineaceae were known to be new host plants of rice stripe virus. The highest infection occurred on Pycreus sanguinolentus grown widly in the wet paddy fold. 3. The number of vectors inoculated on the plants was decreased after 48 hours than that of 24 hours.