• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.25 no.12
• /
• pp.1709-1715
• /
• 2021

In order to accurately extract the necessary text from the web page, the method of specifying the tag and style attributes where the main contents exist to the web crawler has a problem in that the logic for extracting the main contents. This method needs to be modified whenever the web page configuration is changed. In order to solve this problem, the method of extracting the text by analyzing the frequency of appearance of the text proposed in the previous study had a limitation in that the performance deviation was large depending on the collection channel of the web page. Therefore, in this paper, we proposed a method of extracting texts with high accuracy from various collection channels by analyzing not only the frequency of appearance of text but also parent tag paths of text nodes extracted from the DOM tree of web pages.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2021.05a
• /
• pp.584-588
• /
• 2021

The impedance of the speaker is likely to be recognized as a fixed value. However, speaker impedance continues to vary with frequency variation, especially larger in resonant frequency region. The sound pressure level of loudspeakers is determined by the current flowing throughout the coil that consists loudspeakers. If loudspeakers are driven by voltage, sound pressure level of the loudspeaker is distorted by the variation of loudspeaker impedance. Current-drive of loudspeakers can solve this problem, but distortion of sound pressure level occurs in low frequencies due to resonance. The distortion can degrade the sound quality of the sound system. So to solve this problem, In this paper, we propose a resonance compensation circuit using DSP. we simulates audio systems using an equivalent model of loudspeakers to verify distortion of sound pressure level due to impedance variation and propose a circuit to compensate it. The proposed circuit is configured using a state variable filter and it can adjust the center frequency and output, so it will be used various sound systems.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.22 no.11
• /
• pp.1070-1077
• /
• 2011

This paper introduces a radar signal processing technique for intelligent rear view monitoring of an automobile. The linear frequency modulation-frequency shift keying(LFM-FSK) waveform, which is the combination of frequency modulation continuous wave(FMCW) and frequency shift keying(FSK) waveform, is employed to simultaneously estimate the range, relative aspect angle, and velocity of an automobile. Hence, it can be applied to monitor the rear view of an automobile. FMCW waveform has high range resolution capability, but it produces ghost targets under a multiple target environment. In contrast, FSK waveform can provide high velocity resolution and avoids the problem of ghost targets. However, it fails to identify multiple targets along the radar's line of sight. With LFM-FSK waveform, we can estimate the ranges and velocities of multiple targets with very high resolution, which avoids the ghost target problem of an FMCW waveform. Simulation result shows that LFM-FSK wavefrom is suitable for use in the lane change assistance system for an automobile.

• Korean Journal of Child Studies
• /
• v.26 no.5
• /
• pp.1-14
• /
• 2005

The purpose of this study was to examine the relation between forms of children's solitary play and temperament, problem behaviors. Seventy-six children of four-year-olds were observed during free play. Children's temperament was measured by mothers of participants. Children's problem behaviors were measured by teachers. Following from Coplan et al(1994), this study were analyzed three aggregate measures of solitary play consisting of reticent behavior, solitary-passive play, and solitary-active play. The results of this study shows that first, the highest frequency of solitary play's forms was reticent behavior, followed by solitary-passive play, then solitary-active play. There weren't any differences in children's solitary play according to their gender. Second, there were significant differences among forms of children's solitary play and temperament. And there were gender differences in the correlates of different forms of solitary play. Third there were significant differences among forms of children's solitary play and problem behaviors. Also, there were gender differences in the correlates of different forms of solitary play. This result points out the important of solitary play and distintion of solitary play'forms.

• Journal of Korean Home Economics Education Association
• /
• v.12 no.2
• /
• pp.107-122
• /
• 2000

The purposes of this study were to investigate the decision making process & preference for imported products and to suggest the systematic education programs for adolescent consumers. The data for this research were attained from 426 middle & high school students in Pohang. The data were analyzed by frequency distribution. mean standard deviation analysis of variance t-test, χ(sup)2-test and Pearson’s correlation with SAS program. The results of this study were as follows: 1. preference for imported products was significantly different according to sex, amount of pocket money, region. T.V advertising, friends and the attitude of their mothers. 2. Decision making process was composed of 4 dimensions in this study; information sources criteria for products problem experience of consumption and type of problem solving. In case of information sources there was a signifiant difference according to sex. grade level of parents’education. Criteria for products were significantly different according to sex grade. level of father’s education type of father’s job amount of pocket money and how they gained their pocket money. Consumption problem experience & type of problem solving were significantly different according to sex and grade. 3. Preference for imported products was significantly different according to criteria for products and consumption problem experience out of adecision making process.

• International Journal of Aeronautical and Space Sciences
• /
• v.14 no.3
• /
• pp.256-263
• /
• 2013

The saturation of the actuator impairs the response performance of the near space interceptor control system. A control system based on the properties of linear tracking system is designed for this problem. The properties are that the maximum value of the pseudo-Lyapunov function of the linear tracking control system do not present at the initial state but at the steady state, based on which the bounded stability problem is converted into linear tracking problem. The pseudo-Lyapunov function of the linear tracking system contain the input variables; the amplitude and frequency of the input variables affect the stability of the nonlinear control system. Designate expected closed-loop poles area for different input commands and obtain a controller which is function of input variables. The coupling between variables and linear matrices make the control system design problem non-convex. The non-convex problem is converted into a convex LMI according to the Shur complement lemma and iterative algorithm. Finally the simulation shows that the designed optimal control system is quick and accurate; the rationality of the presented design techniques is validated.

• Proceedings of the IEEK Conference
• /
• 2006.06a
• /
• pp.37-38
• /
• 2006

In this paper, we describe a security problem of IPsec. And we propose a solution for this problem. The problem is a fragility of IPsec Gateway which is used in tunnel mode. The role of IPsec Gateway is encrypting or decrypting IPsec packets. Because of the role of IPsec Gateway, IPsec Gateway suffers overhead for decrypting numerous packets. Adversaries can easily attack IPsec Gateway using a DDoS attack. To solve this problem, we propose the "Priority based Random Packet Drop" method. In this method, the white list which is a list of normal users is created. After that, according to the frequency of uses, the method marks priorities of random drops to the white list. If anomalous traffic appeared, this method will drop many packets which consist of anomalous traffic. In simple experiment, we show our solution is proper to defend IPsec Gateway. For this experiment, we use empirical backbone traffic which includes DoS attacks.

• ETRI Journal
• /
• v.37 no.3
• /
• pp.471-479
• /
• 2015

Traditional designs of cognitive radio (CR) focus on maximizing system throughput. In this paper, we study the joint overlay and underlay power allocation problem for orthogonal frequency-division multiple access-based CR. Instead of maximizing system throughput, we aim to maximize system energy efficiency (EE), measured by a "bit per Joule" metric, while maintaining the minimal rate requirement of a given CR system, under the total power constraint of a secondary user and interference constraints of primary users. The formulated energy-efficient power allocation (EEPA) problem is nonconvex; to make it solvable, we first transform the original problem into a convex optimization problem via fractional programming, and then the Lagrange dual decomposition method is used to solve the equivalent convex optimization problem. Finally, an optimal EEPA allocation scheme is proposed. Numerical results show that the proposed method can achieve better EE performance.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.12 no.5
• /
• pp.2063-2081
• /
• 2018

A resource allocation algorithm is proposed in this paper to simultaneously minimize the total system power consumption and maximize the system throughput for the downlink of multi-user multiple input multiple output-orthogonal frequency division multiplexing (MIMO-OFDM) systems. With the Lagrange dual decomposition method, we transform the original problem to its convex dual problem and prove that the duality gap between the two problems is zero, which means the optimal solution of the original problem can be obtained by solving its dual problem. Then, we use convex optimization method to solve the dual problem and utilize bisection method to obtain the optimal dual variable. The numerical results show that the proposed algorithm is superior to traditional single-objective optimization method in both the system throughput and the system energy consumption.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.29 no.10
• /
• pp.783-790
• /
• 2018

The frequency-hopping technique is one of the spread-spectrum techniques. Frequency hopping is a communication system in which the carrier frequency channel is hopped within the wideband. Therefore, a frequency-hopping system has such advantages as antijamming and low probability of intercept. This system is often used in military communications. Because frequency-hopping signal detection is difficult, it is an important research issue. A novel detection technique is proposed that can improve detection probability. When the received signal is transformed to a frequency domain sample by fast Fourier transform, spectral leakage lowers the detection probability. This problem can be solved by using the Hamming window, and the detection probability can be increased. However, in a frequency-hopping environment, the windowing technique lowers the detection probability. The proposed method solves this weakness. The simulation results show that the proposed detection technique improves the detection probability by as much as 13 %.