• Journal of Educational Research in Mathematics
• /
• v.20 no.2
• /
• pp.185-202
• /
• 2010

This study was designed to investigate the possibility that the optimization problem solving activities based on the instrumented CAS can have an influence on the sequence of mathematics curriculum in secondary mathematics education. Some optimization problem solving activities based on CAS were constructed and executed to eleventh grade(the penultimate year of Korean high school) 7 students for nine class hours. They have experienced using CAS in mathematics class for three months, but never learned calculus. The data which consists of classroom observations(audio and video taped) and post-unit interviews with students were analyzed. In the analysis, with CAS, students can highly deal with the applied optimization problems made up of calculus, cubic equation, solution of radical equation, and graph analysis which never learned. This result shows CAS may have an influence on the sequence of mathematics curriculum in secondary mathematics education.

• Journal of applied mathematics & informatics
• /
• v.40 no.1_2
• /
• pp.289-303
• /
• 2022

This article examines the multidimensional index extraction method of the disability social security system based on data mining. While creating the data warehouse of the social security system for the disabled, we need to know the elements of the social security indicators for the disabled. In this context, a clustering algorithm was used to extract the indicators of the social security system for the disabled by investigating the historical dimension of social security for the disabled. The simulation results show that the index extraction method has high coverage, sensitivity and reliability. In this paper, a multidimensional extraction method is introduced to extract the indicators of the social security system for the disabled based on data mining. The simulation experiments show that the method presented in this paper is more reliable, and the indicators of social security system for the disabled extracted are more effective in practical application.

• School Mathematics
• /
• v.11 no.3
• /
• pp.527-546
• /
• 2009

This study was designed to gain insights into instrumental genesis process of CAS in Korean high school students and to explore its practical potentials in secondary mathematics education. Two activities, such as Concept-Centered Mathematics Activity based on CAS and Problem Solving Activities, were constructed and executed to 10th Grade seven students for twelve class hours. The finding on the students' activities are as follows : it is meaningful in mathematics education, especially in algebra education, in that the CAS based concept centered mathematics activity offers great opportunities to deal with high-qualified application problems. The problem solving activities based on the instrumented CAS may have an influence on the sequence of mathematics curriculum, e.g. the optimization problems may precede the calculus problems such as derivatives in high school. The results of this study to investigate the instrumental genesis of CAS in mathematical activities will give insights into the secondary mathematics curriculum to prepare the CAS in Korea.

• Journal of IKEEE
• /
• v.27 no.3
• /
• pp.213-219
• /
• 2023

According to statistics from the National Police Agency, smishing crimes using texts or messengers have increased dramatically since COVID-19. In addition, most of the cases of impersonation of public institutions reported to agency were related to vaccination and reward, and many methods were used to trick people into clicking on fake URLs (Uniform Resource Locators). When detecting them, URL-based detection methods cannot detect them properly if the information of the URL is hidden, and content-based detection methods are slow and use a lot of resources. In this paper, we propose a system for URL-based detection using transformer for regular URLs and content-based detection using XGBoost for shortened URLs through the process of determining shortened URLs using GRU(Gated Recurrent Units). The F1-Score of the proposed detection system was 94.86, and its average processing time was 5.4 seconds.

• Proceedings of the IEEK Conference
• /
• 2002.07b
• /
• pp.830-833
• /
• 2002

To solve the internal security problem such as human error and bad faith, the automation of computer system management is significant. For this purpose, we focus attention in the automation of Mail Delivery Service. Today, requirement for reliable mail delivery system becomes larger and larger. However, existing systems are too strict about their configuration. Hence, we propose the method based on Reinforcement Learning (RL) to achieve proper MX record ordering. A measure on validity of the design of system, such as network topology number of servers and so on, is also obtained as side benefit. In order to verify the usability of the presented method, we did on a small model of mail delivery system. As a result, we show that RL is available for determination of the proper MX record ordering. Additionally, we suggest that it is also available for comparing validity of setting of MTA and the network design.

• Journal of applied mathematics & informatics
• /
• v.6 no.1
• /
• pp.175-184
• /
• 1999

Along with the computation and analysis for nonlinear system being more and more involved in the fields such as automation control electronic technique and electrical power system the nonlin-ear theory has become quite a attractive field for academic research. In this paper we derives the solutions for state equation of nonlinear system by using the inverse operator expression of the so-lutions is obtained. An actual computation example is given giving a comparison between IOM and Runge-kutta method. It has been proved by our investigation that IOM has some distinct advantages over usual approximation methods in that it is computationally con-venient rapidly convergent provides accurate solutions not requiring perturbation linearization or the massive computation inherent in discrietization methods such as finite differences. So the IOM pro-vides an effective method for the solution of nonlinear system is of potential application valuable in nonlinear computation.

• Current Optics and Photonics
• /
• v.2 no.6
• /
• pp.540-546
• /
• 2018

We propose an implementation scheme for an optical encryption system with hybrid-pattern random keys. In the encryption process, a pair of random phase keys composed of a white-noise phase key and a structured phase key are positioned in the input plane and Fourier-spectrum plane respectively. The output image is recoverable by digital reconstruction, using the conjugate of the encryption key in the Fourier-spectrum plane. We discuss the system encryption performance when different combinations of phase-key pairs are used. To measure the effectiveness of the proposed method, we calculate the statistical indicators between original and encrypted images. The results are compared to those generated from a classical double random phase encoding. Computer simulations are presented to show the validity of the method.

• Bulletin of the Korean Mathematical Society
• /
• v.57 no.1
• /
• pp.251-274
• /
• 2020

We study a dynamical system that was originally defined by Romik in 2008 using an old theorem of Berggren concerning Pythagorean triples. Romik's system is closely related to the Farey map on the unit interval which generates an additive continued fraction algorithm. We explore some number theoretical properties of the Romik system. In particular, we prove an analogue of Lagrange's theorem in the case of the Romik system on the unit quarter circle, which states that a point possesses an eventually periodic digit expansion if and only if the point is defined over a real quadratic extension field of rationals.

• Journal of applied mathematics & informatics
• /
• v.17 no.1_2_3
• /
• pp.737-746
• /
• 2005

Average memory occupancy and congestion in computer system or communication system may be reduced further if new jobs are admitted only when the number of jobs queued at CPU is below a certain threshold, run queue cutoff (RQ). In our previous paper we showed that response time of a job is invariant with respect to RQ if jobs do not communicate each other. In this paper, we prove that the invariance property by considering the evolution of the queue lengths as point processes. We also present an approximate method for the delay due to context switching under time slicing.

• Journal of applied mathematics & informatics
• /
• v.16 no.1_2
• /
• pp.539-550
• /
• 2004

We consider communication or computer systems that have the average memory occupancy and congestion. A certain system may be reduced further if new processes are admitted only when the number of processes queued at the processor is below a certain threshold, run queue cutoff(RQ). We show that response time of a process is invariant with respect to RQ when processes do not communicate each other. The invariance property is considered with the evolution of the queue lengths as point processes and demonstrate it numerically using matrix-geometric methods. We illustrate the RQ invariance property.