• Journal of the Korea Computer Industry Society
• /
• v.6 no.5
• /
• pp.675-686
• /
• 2005

This paper proposes a new method of mathematically modeling and computer simulating television ghosts wherein television signals that have undergone multipath fading are generated without using approximations by considering the attenuation, time delay, phase, and timing jitter between consecutive frames. Conventional methods used polynomial interpolation or complex arithmetic to take into account the ghost phase, but our method uses only real arithmetic by employing the Hilbert transform and also reduces the computation time using the FFT (fast Fourier transform) algorithm. Furthermore, it is also possible to observe the transmit waveforms in both RF and IF ranges. Various ghost patterns generated in software provide for essential data required for the development of ghost canceling algorithms, and are deemed to be very useful in analyzing the constituent blocks of the transmitter and receiver chain in television broadcasting. The development of ghost cancelers needs to be preceded by the task of mathematically modeling ghosts and their extensive computer simulations.

• Journal of KIISE:Software and Applications
• /
• v.32 no.8
• /
• pp.795-807
• /
• 2005

The classical approaches for computing Live Variable Analysis(LVA) use iterative algorithms across the entire programs based on the Data Flow Analysis framework. In case of Zephyr compiler, average execution time of LVA takes $7\%$ of the compilation time for the benchmark programs. The classical LVA algorithm has many aspects for improvement. The iterative algorithm for LVA scans useless basic blocks and calculates large sets of variables repeatedly. We propose the improvement of Iterative algorithm for LVA based on used variables' upward movement. Our algorithm produces the same result as the previous iterative algorithm. It is based on use-def chain. Reordering of applying the flow equation in DFA reduces the number of visiting basic blocks and redundant flow equation executions, which improves overall processing time. Experimental results say that our algorithm ran reduce $36.4\%\;of\;LVA\;execution\;time\;and\;2.6\%$ of overall computation time in Zephyr compiler with benchmark programs.

• Journal of KIISE:Software and Applications
• /
• v.29 no.11
• /
• pp.785-794
• /
• 2002

Automatic stock trading systems should be able to solve various kinds of optimization problems such as market trend prediction, stock selection, and trading strategies, in a unified framework. But most of the previous trading systems based on supervised learning have a limit in the ultimate performance, because they are not mainly concerned in the integration of those subproblems. This paper proposes a stock trading system, called R-Trader, based on reinforcement teaming, regarding the process of stock price changes as Markov decision process (MDP). Reinforcement learning is suitable for Joint optimization of predictions and trading strategies. R-Trader adopts two popular reinforcement learning algorithms, temporal-difference (TD) and Q, for selecting stocks and optimizing other trading parameters respectively. Technical analysis is also adopted to devise the input features of the system and value functions are approximated by feedforward neural networks. Experimental results on the Korea stock market show that the proposed system outperforms the market average and also a simple trading system trained by supervised learning both in profit and risk management.

• Journal of KIISE:Software and Applications
• /
• v.30 no.3_4
• /
• pp.268-277
• /
• 2003

A document type definition(DTD) which defines tags for a document is a XML document grammar that defines syntactic structure of a document. An XML document keeps the rules and must be parsed to check validation. To parse XML document, the deterministic parsing method of programming language is irrelevant because it does not satisfy the definition of deterministic content model in element declaration. In this paper, we consider editing of a valid XML document in syntax-directed editing environment, and we suggest the internal storage representations of syntax in DTD and theirs algorithms. The consequence is that a syntactic structure of textual DTD is transformed into graph and table structures. The table structure of DTD is interpreted the context free grammar which has attribute values and is used in syntax-directed editor for XML. We called this the XML abstract grammar and showed generated results and examples.

• Journal of Navigation and Port Research
• /
• v.36 no.6
• /
• pp.429-435
• /
• 2012

Although GNSS hardware and software technologies have been steadily advanced, it is still difficult to obtain reliable positioning results in the area with lots of signal blockage. In this study, algorithms for integrated GPS and GLONASS double difference relative positioning were developed and its performance was validated via simulations of signal blockages. We assumed that signal blockages are caused by high-rise buildings to the east, west, and south directions. And then, GPS-only and integrated GPS/GLONASS positioning accuracy was analysed in terms of 2-dimensional positioning accuracies. Compared with GPS-only positioning, the positioning accuracy of integrated GPS/GLONASS improved by 0.3-13.5 meters.

• KIPS Transactions on Software and Data Engineering
• /
• v.7 no.9
• /
• pp.345-350
• /
• 2018

This study is an algorithm for detecting vein pattern features important for finger vein recognition. The feature detection algorithm is important because it greatly affects recognition results in pattern recognition. The recognition rate is degraded because the reference is changed according to the finger position change. In addition, the image obtained by irradiating the finger with infrared light is difficult to separate the image background and the blood vessel pattern, and the detection time is increased because the image preprocessing process is performed. For this purpose, the presented algorithm can be performed without image preprocessing, and the detection time can be reduced. SWDA (Down Slope Trace Waveform) algorithm is applied to the finger vein images to detect the fingertip position and vein pattern. Because of the low infrared transmittance, relatively dark vein images can be detected with minimal detection error. In addition, the fingertip position can be used as a reference in the classification stage to compensate the decrease in the recognition rate. If we apply algorithms proposed to various recognition fields such as palm and wrist, it is expected that it will contribute to improvement of biometric feature detection accuracy and reduction of recognition performance time.

• Journal of The Korean Association of Information Education
• /
• v.21 no.6
• /
• pp.619-627
• /
• 2017

The purpose of this study is to verify the effectiveness of the Development-oriented model (Discovery-Design-Development: DDD) for developing students' Computational Thinking skills in software education. DDD is a class model that learns the process of developing SW to solve real-life problems through three stages of Discovery, Design, and Development. In order to verify the effectiveness of the DDD, first grade students at G university who did not have SW education class were tested. As a result, the students who experienced SW development through DDD maintained the learning motivation of SW education before and after, especially the confidence area increased significantly. In addition, students also noted that the Design phase was particularly helpful in improving CT abilities and the DDD was a significant help in understanding of decomposition and algorithms.

• Journal of Digital Convergence
• /
• v.15 no.6
• /
• pp.229-236
• /
• 2017

An efficient frequent pattern algorithm is essential for mining association rules as well as many other mining tasks for convergence with its application spread over a very broad spectrum. Models for mining pattern have been proposed using a FP-tree for storing compressed information about frequent patterns. In this paper, we propose a centroid frequent pattern growth algorithm which we called "CAWFP-Growth" that enhances he FP-Growth algorithm by making the center of weights and frequencies for the itemsets. Because the conventional constraint of maximum weighted support is not necessary to maintain the downward closure property, it is more likely to reduce the search time and the information loss of the frequent patterns. The experimental results show that the proposed algorithm achieves better performance than other algorithms without scarifying the accuracy and increasing the processing time via the centroid of the items. The MapReduce framework model is provided to handle large amounts of data via a pseudo-distributed computing environment. In addition, the modeling of the proposed algorithm is required in the fully distributed mode.

• Journal of Digital Contents Society
• /
• v.18 no.7
• /
• pp.1411-1418
• /
• 2017

The batch job scheduler recognizes the computational resources configured in the cluster environment and plays a role of efficiently arranging the jobs in order. In order to efficiently use the limited available resources in the cluster, it is important to analyze and characterize the characteristics of user tasks. To do this, it is important to identify various scheduling algorithms and apply them to the system environment. Most scheduler software reflects the user's work environment, from job submission to termination, as well as the state of the inventory and system status of the entire managed object. It also stores various information related to task execution, such as job scripts, environment variables, libraries, wait for tasks, start and end times. In this paper, we analyze the execution log of the scheduler such as user 's success rate, execution time, and resource size through information related to job execution through batch scheduler. Based on this, it can be used as a basis to optimize the system by increasing the utilization rate of resources.

• Aerospace Engineering and Technology
• /
• v.11 no.2
• /
• pp.49-56
• /
• 2012

LEO Satellite performs the operations and missions by FSW(Flight Software) after separation from a launch vehicle. Many of the operations by FSW are automatically conducted by the algorithms of FSW. In the case of the IAC(Initial Activation and Checkout) operations, a mission scheduling, an orbit transition, etc, however, a decision and a control of the satellite operators or manufacturers are required in order to operate the satellite safely. For this, the wireless communication channel between a satellite and a ground station should be prepared to receive telemetries and to transmit tele-commands for controlling FSW properly. Therefore, the verification of the interface between KOMPSAT-3 and a ground station is essential. This verification test is named the satellite end-to-end test. In this paper, we show the design process of the satellite end-to-end test and test results.