• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.6C
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• pp.285-293
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• 2012

The surface tension, which is generated in the unsaturated soils, increases the stiffness of the soils. The objective of this study is to estimate the effect of the surface tension, which varies according to the temperature, on the shear wave velocity. Nine specimens, which have the different degree of saturation (0%, 2.5%, 5%, 10%, 20%, 40%, 60%, 80%, 100%), are prepared by using sand-silt mixtures. Experiments are carried out in a nylon cell designed for the measurement of shear waves. A pair of bender elements, which are used for the generation and detection of shear waves, is installed as a cross-hole type. The shear waves are continuously monitored and measured as the temperature of specimens decreases from $15^{\circ}C$ to $1^{\circ}C$. The results show that shear wave velocities of the fully saturated and fully dried specimens change a little bit as the temperatures of specimens decrease. However, the shear wave velocities of the specimens with the degree of saturations of 2.5%, 5%, 10%, 20%, 40%, 60% and 80% continuously increase as temperature decreases from $15^{\circ}C$ to $1^{\circ}C$. Furthermore, a fully saturated specimen is dried at the temperature of $70^{\circ}C$ in order to observe the shear waves according to degree of saturation. The shear wave velocities measured at the temperature of $70^{\circ}C$ are generally lower than those measured at temperature of $15^{\circ}C$. This study demonstrates that the dependence of shear wave velocities on the temperature according to the degree of saturation should be taken into account in both laboratory and field tests.

• Journal of Korea Water Resources Association
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• v.36 no.3 s.134
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• pp.413-422
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• 2003

Numerical analysis for the Bragg reflection due to sinusoidally varying seabeds tying on a sloping beach was performed by using a couple of ordinary differential equations derived from the Boussinesq equations. Incident waves were wane groups generated by two short waves with slightly different phases. Effects of the slope of a seabed to the reflection were investigated in detail. It is shown that the reflection of long waves enhanced by increasing the slope of a seabed. This phenomenon caused by increase of wave amplitude due to increase of nonlinearity and shoaling.

• Journal of Korea Multimedia Society
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• v.6 no.7
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• pp.1312-1320
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• 2003

In this paper, we consider a multilayer neural network, with a single hidden layer. Error backpropagation learning method used widely in multilayer neural networks has a possibility of local minima due to the inadequate weights and the insufficient number of hidden nodes. So we propose a fuzzy supervised learning algorithm by using self-generation that self-generates hidden nodes by the compound fuzzy single layer perceptron and modified ART1. From the input layer to hidden layer, a modified ART1 is used to produce nodes. And winner take-all method is adopted to the connection weight adaptation, so that a stored pattern for some pattern gets updated. The proposed method has applied to the student identification card images. In simulation results, the proposed method reduces a possibility of local minima and improves learning speed and paralysis than the conventional error backpropagation learning algorithm.

• Journal of the Korean Chemical Society
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• v.37 no.10
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• pp.888-894
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• 1993

The electrochemical behaviors of copper-1-(2-pyridylazo)-2-naphthol(Cu-PAN) complex in acetonitrile (AN) solution have been investigated by the use of cyclic voltammetry, DC-polarography, controlled potential coulometry and UV-Vis spectroscopy. Cu-PAN complex in acetonitrile exhibit three reduction waves at -1.27 V, -1.64 V and -2.08 V vs. Ag/AgNO$_3$(AN). The numbers of electron involved in each reduction step was calculated with controlled potential coulometry, and reduction product was identified with UV-Vis spectrum. As the result, we proposed the reduction mechanism of the Cu-PAN complex in acetonitrile.

• Proceedings of the Korea Water Resources Association Conference
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• 2010.05a
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• pp.739-743
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• 2010

본 연구에서는 확산파 기반의 2차원 침수해석 모형을 이용하여 울산광역시 태화강 유역에 대하여 침수시 건물 안으로의 흐름은 없다는 가정 하에서 건물로 인한 흐름의 양상, 침수심, 침수위등을 분석하였다. 지형자료는 최근 대도시를 중심으로 구축되고 있는 1m 간격으로 수집된 LiDAR 자료를 바탕으로 10m간격의 정형격자를 통하여 지형자료를 생성하였으며, 수치지도로부터 추출된 건물을 ArcView 등의 GIS Tool을 활용하여 LiDAR 자료와 합성하여 2차원 침수해석에 적용되는 지형자료를 구성하였다. 200년 빈도의 확률강우에 대한 유출해석 결과를 이용하여 FLDWAV 모형을 적용한 태화강에 대한 1차원 하천해석을 실시하였고, 제방파제에 대한 가상의 시나리오를 생성하여 파제에 따른 외수범람에 대한 2차원 침수해석을 실시하였으며, 침수해석 결과를 각 시간별로 가시화함으로써 효율적이며 정확한 침수해석 방법을 제안하고자 하였다. 침수해석 결과에 대한 분석을 통하여 침수면적에 따른 적합도가 건물의 영향을 고려한 경우와 그렇지 않은 경우를 비교한 결과 90%이하로 떨어지는 것을 확인하였고, 침수심과 침수위에 대한 분석을 통하여 침수심은 건물 영향 고려시 낮게 산정되나 침수위로 고려시 높은 수위 값을 나타내는 것을 확인하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.10
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• pp.845-849
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• 2013

In this paper, we design local signals to remove side-peaks in the binary offset carrier (BOC) autocorrelation. Specifically, we first investigate why local signals of the conventional schemes are applicable to either sine or cosine-phased BOC signals, and then, design local signals applicable to both sine and cosine-phased BOC signals. Finally, we obtain two partial correlations and propose a correlation function with no side-peak via a combination of the partial correlations. From numerical results, we demonstrate that the designed local signals are applicable to both sine and cosine-phased BOC signals and can remove side-peaks completely.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.15 no.2
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• pp.13-22
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• 2005

To improve the anomaly IDS using system calls, this study focuses on Neural Networks Learning using the Soundex algorithm which is designed to change feature selection and variable length data into a fixed length learning pattern. That is, by changing variable length sequential system call data into a fixed length behavior pattern using the Soundex algorithm, this study conducted neural networks learning by using a backpropagation algorithm with fuzzy membership function. The back-propagation neural networks and Neuro-Fuzzy technique are applied for anomaly intrusion detection of system calls using Sendmail Data of UNM to demonstrate its aspect of he complexity of time, space and MDL performance.

• Annual Conference of KIPS
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• 2007.11a
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• pp.104-107
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• 2007

인간은 초점정보를 이용하여 단안만으로도 공간의 깊이를 지각할 수 있다. 이것은 한 번에 하나의 대상물에만 초점을 맞출 수 있고 그 외의 부분은 흐림 현상을 유도함으로써 이루어진다. 이는 초점이 맞는 대상물체로부터 멀어지면 멀어질수록 흐림 현상이 강해지는 원리를 이용한 것으로 주파수 성분의 변화량에 대한 연산과 깊은 관련이 있다. 본 논문에서는 이와 같은 인간의 시각 시스템의 요소 중 하나인 초점정보를 모방하여 초점거리가 다른 각각의 이미지들에 각각의 가중치를 부여하였다. 그리고 각 이미지들을 일정 블록으로 각각 분할하여 초점이 가장 잘 맞는 블록을 찾아내어 하나의 이미지로 통합하였다. 이때 각 영역은 자신이 속했던 이미지의 가중치를 따르게 한다. 각 이미지에서 가장 포커스 수치가 높은 영역을 찾기 위한 방법으로 주파수 영역 기반 처리와 공간 영역 기반 처리를 결합 하였다. 주파수 기반으로는 FFT(Fast Fourier Transform)에서 고주파 부분의 영역을 뽑아내어 포커스수치를 계산하였으며, 공간 영역 처리 기반으로는 이웃픽셀과의 차이가 임계값이하인 것을 제외한 영역을 뽑아내어 저주파 영역의 연산을 제거하는 방법과 단순히 Laplacian measure만을 사용하여 저주파까지도 포함한 방법의 두 가지를 적용하였다. 최종적으로 3개의 포커스 측정값을 결합시켜 포커스 수치를 계산한 후 각 블록의 가중치에 맞게 하나의 이미지로 통합하여 상대적 깊이지도를 생성하였다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.1 s.104
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• pp.45-51
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• 2006

In this paper, a new predistortion linearizer for controlling the amplitude of low frequency intermodulation distortion signals is proposed. The low frequency intermodulation distortion(IMD) components are generated by harmonic generator. A vector modulator, modulate fundamental signal with low frequency IMD signals, generates predistortion IMD signals and controls amplitude and phase of them with modulation factors. As a result, this predistorter is suppressed IMD signals of power amplifier effectively. The predistortion linearizer has been manufactured to operate in cellular base-station transmitting band($869{\sim}894\;MHz$). The experimental results show that IMD3 of power amplifier are improved more than 20 dB for CW two-tone signals. Also, it's improved the adjacent channel power ratio(ACPR) more than 10 dB for IS-95 CDMA IFA signals.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.12 s.103
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• pp.1239-1245
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• 2005

In this paper, a new predistortion linearizer using second harmonic components feedforwarding is proposed. The harmonic generator of the proposed predistorter that consists of a small signal amplifier extracts second harmonic signals. A vector modulator that modulate fundamental signal with second harmonic signals, generates the inverse third order intermodulation distortion signals and controls amplitude/phase of them with modulation factors. As a result, this linearizer is suppressed IMD3 signals of power amplifier effectively. The test results show that the third order IMD of power amplifier is suppressed more than 20 dB for CW two-tone signals. Also, it's improved the adjacent channel power ratio(ACPR) more than 5 dB for CDMA(IS-95) 4FA signals.