• Transactions of the Korean Society of Machine Tool Engineers
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• v.15 no.3
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• pp.73-81
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• 2006

This paper describes our primary study for a new method of recognizing materials, which is need for precision work system. This is a study of dynamic characteristics of smart sensors, new method$(R_{SAI})$ has the sensing ability of distinguishing materials. Experiment and analysis are executed for finding the proper dynamic sensing condition. First, we developed advanced smart sensor. We made smart sensors for experiment. The type of smart sensor is HH type. The smart sensor was developed for recognition of material. Second, we develop new estimation methods that have a sensing ability of distinguish materials. Dynamic characteristics of sensor are evaluated through new recognition index$(R_{SAI})$ that ratio of sensing ability index. Distinguish of object is executed with $R_{SAI}$ method relatively. We can use the $R_{SAI}$ method for finding materials. Applications of this method are finding abnormal condition of object (auto-manufacturing), feeling of object(medical product), robotics, safety diagnosis of structure, etc.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.6
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• pp.1356-1363
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• 2005

In the gyrocompass system, the use of the fiber optic gyroscope(FOG) makes this traditional system considerably attractive because it has strong points in terms of weight, power, warming-up time, and cost. In this paper, a novel digital north-finding method based upon an FOG, which can be applied to the gyrocompass system, is proposed. The analytical model for the earth signal of the FOG is described, and the earth signals passed through lock-in amplifiers are modeled. Additionally, a north-finding algorithm using two lock-in amplifier outputs is developed, and the proposed method is organized by the developed algorithm. Simulation results are included to verify the performance of the proposed method.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.11
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• pp.3104-3109
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• 2009

The technology of direction finding is very important to find the direction of emitters for ELINT(electronic intelligence) system. The principle of TDOA(time difference of arrival) is to receive an emitter signal with two antennas, measure the time difference between two antennas, and converse the time difference to direction difference. This technology can be used in broadband frequency system and make the system very simple because a phase-discriminator and a voltage comparator are not needed. For fine DF accuracy, high time resolution receiver and long basis line antennas are needed. The DF accuracy of noise added signals is simulated with different time

• Proceedings of the Korea Society for Industrial Systems Conference
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• 2008.10b
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• pp.449-454
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• 2008

Finding an energy efficient route is one of the very important issues in the wireless sensor networks. The route scheme should consider both of the energy level of sensor nodes and the number of hops at the same time. First of all, this paper proposes an optimum routes finding scheme (ORFS), which could be used in the sensor network routing protocols. The scheme uses an optimum value for the path with the considerations of both the minimum energy level of a path and the number of hops at the same time. After that, this paper proposes a routing protocol based on the ORFS for how it could be used for the multipath directed diffusion with data aggregation (MDD-A), to get the better energy efficiency. The analysis result shows that the proposed routing protocol could lengthen the network life cycle about 18.7% compared to the previous MDD-A related protocols.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.4
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• pp.723-730
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• 2017

In this paper, we consider an online compensation algorithm considering the mutual coupling and suggest a new GPS antenna array to apply. To evaluate the anti-jamming performance for the proposed antenna array, ULA and URA, we divide direction finding of multiple jamming signals into environments. 1. there is no mutual coupling. 2. there is mutual coupling but no compensation. 3. mutual coupling is compensated. RMSE analysis showed that the online compensation algorithm works and that peak detection is possible for multiple jamming signals.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.2
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• pp.168-177
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• 2008

Path finding is a key element in the navigation of a mobile robot. To find a path, robot should know their position exactly, since the position error exposes a robot to many dangerous conditions. It could make a robot move to a wrong direction so that it may have damage by collision by the surrounding obstacles. We propose a method obtaining an accurate robot position. The localization of a mobile robot in its working environment performs by using a vision system and Virtual Reality Modeling Language(VRML). The robot identifies landmarks located in the environment. An image processing and neural network pattern matching techniques have been applied to find location of the robot. After the self-positioning procedure, the 2-D scene of the vision is overlaid onto a VRML scene. This paper describes how to realize the self-positioning, and shows the overlay between the 2-D and VRML scenes. The suggested method defines a robot's path successfully. An experiment using the suggested algorithm apply to a mobile robot has been performed and the result shows a good path tracking.

• Journal of Korea Game Society
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• v.15 no.4
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• pp.157-168
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• 2015

The difficulty of the game is closely related to the fun of the game. However, it is not easy to determine the appropriate level of difficulty of the game. In most cases, human playtesting is required. But even so, it is still hard to quantitatively evaluate difficulty of the game. Thus, if we perform quantitative evaluation of the difficulty automatically it will be very helpful in game developments. In this paper, we use a path finding algorithm to evaluate difficulty of exploration in a game level. Exploration is a basic attribute in common video games and it represents the overall difficulty of the game level. We also optimize the proposed evaluation algorithm by using previous exploration histories when available area in an game level is dynamically expanded and the new search is required.

• Journal of the Korea Society for Simulation
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• v.14 no.3
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• pp.21-31
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• 2005

In state-of-the-art games, characters can move in a goal-directed manner so that they can move to the goal position without colliding obstacles. Many path-finding methods have been proposed and implemented for these characters and most of them use the A* search algorithm. When .the map is represented with a regular grid of squares or a navigation mesh, it often takes a long time for the A* to search the state space because the number of cells used In the grid or the mesh increases for higher resolution. Moreover the A* search on the grid often causes a zigzag effect, which is not optimal and realistic. In this paper we propose to use visibility graphs to improve the search time by reducing the search space and to find the optimal path. We also propose a method of taking into account the size of moving characters in the phase of planning to prevent them from colliding with obstacles as they move. Simulation results show that the proposed method performs better than the grid-based A* algorithm in terms of the search time and space and that the resulting paths are more realistic.

• Journal of the Korea Society of Computer and Information
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• v.21 no.12
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• pp.131-137
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• 2016

In this paper, the peak finding algorithms corresponding to the Autocorrelation Function (ACF), which are widely exploited for detecting the pitch of voiced signal, are proposed. According to various researchers, it is well known fact that the estimation of fundamental frequency (F0) in speech signal is not only very important task but quite difficult mission. The proposed algorithms, presented in this paper, are implemented by using many characteristics - such as monotonic increasing function - of ACF function. Thus, the proposed algorithms may be able to estimate both reliable and correct the fundamental frequency as long as the autocorrelation function of speech signal is accurate. Since the proposed algorithms may reduce the computational complexity it can be applied to the real-time processing. The speech data, is composed of Korean emotion expressed words, is used for evaluation of their performance. The pitches are measured to compare the performance of proposed algorithms.

• Korean Journal of Bronchoesophagology
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• v.6 no.1
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• pp.21-28
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• 2000

Background:Subacute necrotizing lymphadenitis or Kikuchi's disease is unknown ethiology and self-limiting process. This disease predominantly affects young women age but rarely affects pediatrics, and usually manifests as lymphadenopathy and fever. Even though this disease is self-limited, benign process, many cases are misidentified as malignant lymphoma. The purpose of this study is to report the clinicopathologic finding, radiological finding and many labolatory test and to compare with characteristics of adult patients in this disease. Meterial and Methods:We reviewed 27 pediarics patients with subacute necrotizing lymphadenitis by excision biopsy or fineneedle aspiration cytology.Result:The most common symptomes were palpation of cervical lymh node(88.9%) and fever(66.7%). The common site of the involvement was cervical lymph node. The multiple involvement was 93% and bilateral involvement was 59%. Leukopenia(52%) and elevated erythrocyte sedimentation rates(93%) appeared in abnormal laboratory data. Microscopically, the characteristic finding was the wide area of florid nuclear dusts engulfed by histiocytes and well-circumscrbed area with eosinophilic fibrinoid material. There was a striking degree ofkaryorrhexis and an absence of granulocyte with paucity of plasma cell. All patients recovered with the conservative treatment and there was no specific complication and recurrence. Conclusion : We reviewed pediatric patients with this disease. Characteristics of this disease inpediatric patients were similar to adult patients.