• Journal of Korean Society of Industrial and Systems Engineering
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• v.39 no.1
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• pp.98-104
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• 2016

With the development of modern science and technology, weapon systems such as tanks, submarines, combat planes, radar are also dramatically advanced. Among these weapon systems, the ballistic missile, one of the asymmetric forces, could be considered as a very economical means to attack the core facilities of the other country in order to achieve the strategic goals of the country during the war. Because of the current ballistic missile threat from the North Korea, establishing a missile defense (MD) system becomes one of the major national defense issues. This study focused on the optimization of air defense artillery units' deployment for effective ballistic missile defense. To optimize the deployment of the units, firstly this study examined the possibility of defense, according to the presence of orbital coordinates of ballistic missiles in the limited defense range of air defense artillery units. This constraint on the defense range is originated from the characteristics of anti-ballistic missiles (ABMs) such as PATRIOT. Secondly, this study proposed the optimized mathematical model considering the total covering problem of binary integer programming, as an optimal deployment of air defense artillery units for defending every core defense facility with the least number of such units. Finally, numerical experiments were conducted to show how the suggested approach works. Assuming the current state of the Korean peninsula, the study arbitrarily set ballistic missile bases of the North Korea and core defense facilities of the South Korea. Under these conditions, numerical experiments were executed by utilizing MATLAB R2010a of the MathWorks, Inc.

• School Mathematics
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• v.13 no.4
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• pp.581-598
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• 2011

Given the growing agreement that algebra should be taught in the early stage of the curriculum, considerable studies have been conducted with regard to early algebra in the elementary school. However, there has been lack of research on how to organize mathematic lessons to develop of algebraic reasoning ability of the elementary school students. This research attempted to gain specific and practical information on effective algebraic teaching and learning in the elementary school. An exploratory qualitative case study was conducted to the fourth graders. This paper focused on the associative law of the multiplication. This paper showed what kinds of activities a teacher may organize following three steps: (a) focus on the properties of numbers and operations in specific situations, (b) discovery of the properties of numbers and operations with many examples, and (c) generalization of the properties of numbers and operations in arbitrary situations. Given the steps, this paper included an analysis on how the students developed their algebraic reasoning. This study provides implications on the important factors that lead to the development of algebraic reasoning ability for elementary students.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37C no.11
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• pp.1036-1044
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• 2012

Thanks to progressive development of IT technology, the number of intelligent devices communicating each other through an In-Vehicle Network(IVN) has been steadily increasing. It is expected that the required network bandwidth and network nodes for vehicle control in 2015 will be increased by two times and one and half times as compared to in 2010, respectively. As a result, many researchers in automotive industry has showed a significant interest on industrial Ethernets, such as EtherCAT and TTEthernet. This paper addresses an analysis on transmission delay and fault recovery performance with an EtherCAT network which is being considered as an IVN. A mathematical model based on the analysis is verified through a set of experiments using an experimental network setup.

• Education of Primary School Mathematics
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• v.2 no.1
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• pp.3-13
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• 1998

In mathematics education we have focused on how to improve the problem-solving ability, which makes its way to the new direction with the introduction of meta-cognition. As meta-cognition is based on cognitive activity of learners and concerned about internal properties, we may find a more effective way to generate learners problem-solving power. Its means that learners can regulate cognitive process according to their gorls of learning by themselves. Moreover, they are expected to make active participation through this process. If specific meta problems designed to develop meta-cognition are offered, learners are able to work alone by means of their own cognition and regulation while solving problems. They can transfer meta-cognition to the other subjects as well as mathematics. The studies on meta-cognition conducted so far may be divided into these three types. First in Flavell(［3］) meta-cognition is defined as the matter of being conscious of one's own cognition, that is, recognizing cognition. He conducted an experiment with presschoolers and children who just entered primary school and concluded that their cognition may be described as general stage that can not link to specific situation in line with Piaget. Second, Brown(［1］, ［2］) and others argued that meta-cognition means control and regulation of one's own cognition and tried to apply such concept to classrooms. He tried to fined out the strategies used by intelligent students and teach such types of activity to other students. Third, Merleary-Ponty (1962) claimed that meta-cognition is children's way of understanding phenomena or objects. They worked on what would come out in children's cognition responding to their surrounding world. In this paper following the model of meta-cognition produced by Lester (［7］) based on such ideas, we develop types of meta-cognition. In the process of meta-cognition, the meta-cognition working for it is to be intentionally developed and to help unskilled students conduct meta-cognition. When meta-cognition is disciplined through meta problems, their problem-solving power will provide more refined methods for the given problems through autonomous meta-cognitive activity without any further meta problems.

• Journal of Korean Society of Water and Wastewater
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• v.25 no.4
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• pp.581-589
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• 2011

Generally, treated water or raw water is transported into storage reservoirs which are receiving facilities of local governments from multi-regional water supply systems. A water supply control and operation center is operated not only to manage the water facilities more economically and efficiently but also to mitigate the shortage of water resources due to the increase in water consumption. To achieve the goal, important information such as the flow-rate in the systems, water levels of storage reservoirs or tanks, and pump-operation schedule should be considered based on the resonable water demand forecasting. However, it is difficult to acquire the pattern of water demand used in local government, since the operating information is not shared between multi-regional and local water systems. The pattern of water demand is irregular and unpredictable. Also, additional changes such as an abrupt accident and frequent changes of electric power rates could occur. Consequently, it is not easy to forecast accurate water demands. Therefore, it is necessary to introduce a short-term water demands forecasting and to develop an application of the forecasting models. In this study, the forecasting simulator for water demand is developed based on mathematical and neural network methods as linear and non-linear models to implement the optimal water demands forecasting. It is shown that MLP(Multi-Layered Perceptron) and ANFIS(Adaptive Neuro-Fuzzy Inference System) can be applied to obtain better forecasting results in multi-regional water supply systems with a large scale and local water supply systems with small or medium scale than conventional methods, respectively.

• Journal of Biosystems Engineering
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• v.38 no.4
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• pp.327-334
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• 2013

Purpose: The purpose of this study was to analyze for resonant frequency, vibration transmissibility and damping ratio of multi-layered corrugated structures using a random vibration test. Methods: The random vibration test was performed by the ASTM D4728 specifications using two paperboards (S120, K180) and two types of flutes (A/F, B/F). Damping ratio of the multi-layered corrugated structures was estimated using a theoretical equation derived from the measured resonant frequency and transmissibility. Results: The resonant frequency and vibration transmissibility of the multi-layered corrugated structures of K180 and B-flute were higher than those of S120 and A-flute, respectively; however, the damping ratio of each sample had the opposite tendency. The resonant frequency was inversely proportional to the sample thickness and static stress; vibration transmissibility and damping ratio were not correlated with sample thickness and static stress. In addition, we developed a mathematical model of the resonant frequency with variables of sample thickness and static stress. Conclusions: Results of this study can be useful for environment-friendly and optimal packaging design since vibration has been a key factor in cushioning packaging design.

• Archives of design research
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• v.16 no.1
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• pp.15-24
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• 2003

In the latest date, vehicles are offered to the drivers, not only the skill for shifting but the pleasure for driving vehicles that are existing today can be a social problem because the amount of vehicles that are increasing give difficulty for the traffic facilities and parking expansion. these day 80% of four wheeled vehicle carriers single or double person the reducing car scale is an important thing about the financial good use resources of energy and the storage of environment. A solution for these problem is a new general idea vehicle development for one or two person to ride. For the sake of these reasons, first, the information is collected and analyzed about existing foreign countries production. Car external design is intended by mathematical modeling, simulation and model testing about frame system of new concept specially we would like to show three wheeled vehicle that has active tilt control(ATC) system. This car tilts actively by the center rotation wheel and frame when the vehicle turns.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.12
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• pp.856-864
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• 2019

The weapon-target assignment (WTA) problem is a matter of effectively allocating weapons to a number of threats. The WTA in a rapidly changing dynamic environment of engagement must take into account both of properties of the threat and the weapon and the effect of the previous decision. We propose a method of applying the Greedy Randomized Adaptive Search Procedure (GRASP) algorithm, a kind of meta-heuristic method, to derive optimal solution for a dynamic WTA problem. Firstly, we define a dynamic WTA problem and formulate a mathematical model for applying the algorithm. For the purpose of the assignment strategy, the objective function is defined and time-varying constraints are considered. The dynamic WTA problem is then solved by applying the GRASP algorithm. The optimal solution characteristics of the formalized dynamic WTA problem are analyzed through the simulation, and the algorithm performance is verified via the Monte-Carlo simulation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.4
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• pp.703-715
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• 2017

In this paper, we analyze the channel characteristics of the long distance air-ground wideband common data link and we propose a mathematical method to analyze the effect of narrowband and wideband interference of air-ground channel on the received signal of wideband data link. In this paper, we analyze the reception performance according to the communication distance using the proposed performance analysis method, and found out that the communication distance is limited by the narrowband and wideband interference of ground reflection wave. As a result of the performance analysis of the method of controlling the receiving antenna upward, not only the narrow band but also the wideband interference is effectively reduced, so that the communication distance is increased even in the existing wideband data link not including the equalizer.

• Journal of Magnetics
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• v.18 no.4
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• pp.481-486
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• 2013

An electromagnetic launcher (EML) system accelerates and launches a projectile by converting electric energy into kinetic energy. There are two types of EML systems under development: the rail gun and the coil gun. A railgun comprises a pair of parallel conducting rails, along which a sliding armature is accelerated by the electromagnetic effects of a current that flows down one rail, into the armature and then back along the other rail, but the high mechanical friction between the projectile and the rail can damage the projectile. A coil gun launches the projectile by the attractive magnetic force of the electromagnetic coil. A higher projectile muzzle velocity needs multiple stages of electromagnetic coils, which makes the coil gun EML system longer. As a result, the installation cost of a coil gun EML system is very high due to the large installation site needed for the EML. We present a coil gun EML system that has a new structure and arrangement for multiple electromagnetic coils to reduce the length of the system. A mathematical model of the proposed coil gun EML system is developed in order to calculate the magnetic field and forces, and to simulate the muzzle velocity of a projectile by driving and switching the electric current into multiple stages of electromagnetic coils. Using the proposed design, the length of the coil gun EML system is shortened by 31% compared with a conventional coil gun system while satisfying a target projectile muzzle velocity of over 100 m/s.