• The Journal of the Korea institute of electronic communication sciences
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• v.6 no.5
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• pp.717-722
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• 2011

This paper presents that the electronic controller is developed for controlling the setting temperature and water in the ceramic pipe system. The heating water system is designed for controlling the temperature to supply the heat through the ceramic pipe heater to input the water, also for controlling quantity of water using the water sensor and impeller. The control method of the heating water system is applied the mathematic modeling of the ceramic pipe heater on the suppling the heat at coming water, and the test result of the electronic controller is present to smartly control the setting temperature, therefore the ceramic pipe heater is proposed to be able to apply the heating structure and the control methods as a product.

• Journal of the Korean Society of Propulsion Engineers
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• v.8 no.4
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• pp.91-101
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• 2004

With the mathematic linear model of a combustor which consists of a combustion chamber and injectors, the analysis of low frequency dynamic characteristics of a liquld-propellant rocket engine combustor was performed. Propellant mass flowrate was varied by combustion chamber pressure feedback, therefore low frequency oscillation was appeared. Increasing the time constant of a combustion chamber and injector pressure differences and decreasing combustion time delay increased the combustor system stability. The variation of injector time constant little affected stability. The system was always stable, when there was no combustion time delay. Increasing combustion time delay decreased oscillation frequency and damping ratio, and the system eventually became unstable.

• Journal of the Korean Solar Energy Society
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• v.23 no.3
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• pp.37-44
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• 2003

This paper presents the modeling and analysis of V47-660 kW wind turbine generation system(WTGS) in Jeju wind farm using Psim program. Generally, WTGS is composed of complicated machinery. So it is very difficult to present the mathematic model. This means that WTGS has a nonlinear system. Using the real output data from V47 WTGS for one year, it is simply possible to express the rotor and gear coupling system as a torque generator according to wind speed. Also, the modeling of electrical system can be able to present using the data sheet from the company. To analyze the proposed method, results of computer simulation using Psim program are presented to support the discussion.

• Journal of Korea Society of Digital Industry and Information Management
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• v.9 no.4
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• pp.103-110
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• 2013

In Information Technology era, various amazing IT technologies, for example Big Data, are appearing and are available as the amount of information increase. The number of counselling for violation of personal data protection is also increasing every year that it amounts to over 160,000 in 2012. According to Korean Privacy Act, in the case of treating unique personal identification information, appropriate measures like encipherment should be taken. The technologies of encipherment are the most basic countermeasures for personal data invasion and the base elements in information technology. So various cryptography algorithms exist and are used for encipherment technology. Therefore studies on safer new cryptography algorithms are executed. Cryptography algorithms started from classical replacement enciphering and developed to computationally secure code to increase complexity. Nowadays, various mathematic theories such as 'factorization into prime factor', 'extracting square root', 'discrete lognormal distribution', 'elliptical interaction curve' are adapted to cryptography algorithms. RSA public key cryptography algorithm which was based on 'factorization into prime factor' is the most representative one. This paper suggests algorithm utilizing telescoping series as a safer cryptography algorithm which can maximize the complexity. Telescoping series is a type of infinite series which can generate various types of function for given value-the plain text. Among these generated functions, one can be selected as a original equation. Some part of this equation can be defined as a key. And then the original equation can be transformed into final equation by improving the complexity of original equation through the command of "FullSimplify" of "Mathematica" software.

• Industrial Engineering and Management Systems
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• v.11 no.1
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• pp.48-53
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• 2012

Due to the customer needs of reducing cost and delivery date shorting, prompt change in the production plan became more important. In the multi period system (For instance, production line.) where target processing time exists, production, idle and delay risks occur repeatedly for multiple periods. In such situations, delay of one process may influence the delivery date of an entire process. In this paper, we discuss the minimum expected cost of the case mentioned above, where the risk depends on the previous situation and occurs repeatedly for multiple periods. This paper considers the optimal switching frequency to minimize the total expected cost of the production process. In this paper, first, the optimal switching frequency model is proposed. Next, the mathematic formulation of the total expectation is presented. Finally, the policy of optimal switching frequency is investigated by numerical experiments.

• Journal of KIISE:Databases
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• v.31 no.3
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• pp.243-251
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• 2004

Most programs of bioinformatics provide biochemists and biologists retrieve and analysis services of gene and protein database. As these services retrieve database for each arrival of user's request, it takes a long time and increases server's load and response time. In this paper. by utilizing database retrieval patterns of sequence alignment programs in bioinformatics, grouping method is proposed to share database retrieval between many requests. Carpool method is also proposed to reduce response time as well as to increase system expandability by combining new arriving requests with the previous on going requests. The performance of our two proposed schemes is verified by mathematic analysis and simulation.

• Proceedings of the KIEE Conference
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• 2003.11c
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• pp.965-967
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• 2003

Fuzzy Controller is a system that displays a person's thoughts using membership function and IF-THEN rules. With the help of specialists' knowledge, rule bases can be explained in easy language. Furthermore Fuzzy Controller has strong resistance against turbulence. Its performance is especially prominent when targets cannot be measured in mathematic methods because the fuzzy controller can measure the output using only the relations between the input and output. With the increasing influence of multimedia on our daily lives, vision plays bigger role both in industries and personal lives. Like wise vision is being used in many areas such as detecting and identifying objects. It is difficult to detect and control targets because there is a delay in the calculating when using vision in detecting and controlling objects in large quantity. In this paper we showed how to use fuzzy controller in minimizing the calculation process, controlling target objects and moving view window instead of applying input variation through vision. Ball beam, which has strong nonlinear, was used as the target object and DSP320C6711 IDK by TI(Texas Instruments) company was for the benefit of speedy calculation and vision data operation.

• The Mathematical Education
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• v.49 no.4
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• pp.501-522
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• 2010

In this study, 'Instruments of the achievement attribution in mathematical learning' was develop to investigate the reasons of mathematical learning achievement by reflecting Korean middle school and high school students' psychological characters and learning context in mathematical learning. To develop the appropriate items for the achievement attribution in mathematical learning, after reviewing attribution literature thoroughly, first version of the instrument was developed and Exploratory Factor Analysis and Confirmatory Factor Analysis were conducted. Then, to reduce the effect of the gender difference and achievement level difference, Differential Item Functioning was performed. Also, using Multiple group Confirmatory Factor Analysis, this instrument was investigated to see whether this can be used for both middle school and high school. The final items for success attribution are 3 items for luck, 3 items for effort, 2 items for ability. The failure attribution were composed of 3 items for luck, 3 items for effort, 2 items for ability, and 2 items for other. The instrument was developed by using large samples and psychometric analysis. Therefore, mathematic teachers can use this instrument efficiently to make a foundation for better learning environment so students' cognitive area and affective area can be harmonized.

• Communications of Mathematical Education
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• v.23 no.3
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• pp.785-801
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• 2009

The education of mathematics is comprised of formal thoughts so students lose interest and they don't have a chance to have a liberal mind. To solve this problem, recently, the flow of mathematic education is changing from formal mathematics to experimental mathematics, which focuses on student's activity and experience. Experimental mathematics can improve student's interest and participation. This study is about teaching methods of trigonometric functions through experimental mathematics measuring height and width of buildings. For measuring height of buildings we use clinometer and for measuring width of buildings we developed a mathematical tool with which we can measure angle for width of buildings. Through this activity, students obtained an interest in mathematics and they gained a positive attitude for the lesson. If we use this experimental mathematics method in high school, it's possible to reduce fears of mathematics and to increase an interest for mathematics.

• Journal for History of Mathematics
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• v.18 no.4
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• pp.29-38
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• 2005

This Paper discusses the history of the conflicts between synthesis and analysis, from those in heuristic and logic development style in ancient Greek to those in projective geometric methods. The two methods, which originally displayed difference in heuristic, offer the base for the two fields of geometry, the analytic geometry and the synthetic geometry in the 18th century as they originated from the field of geometry. As to the 19th century, they even display antagonistic aspects derived by having other perspectives about the true nature of mathematic but finally lose the reason of conflict as the ancient times when the dialectical sublation of both had been proposed.