• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.901-905
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• 2005

It is very important to arrange landmarks when a mobile robot needs to measure its own location. So, it has been discussed often how to arrange landmarks in the optimal way until now. We, there, chose the RFID (Radio frequency Identification) tags as landmarks which can be observed by a mobile robot, and demonstrated the possibility of the optimal arrangement of them. For this work first, we defined the optimization problem and its parameters for the arrangement of tags. Second, we proposed the algorithm which can be applied to the optimization problem. Finally we could obtain closely optimal and practical arrangement with the minimum number of landmarks which satisfied the necessary condition by experimentation.

• Education of Primary School Mathematics
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• v.4 no.1
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• pp.75-82
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• 2000

The purpose of this study is to investigate the recognition fur mathematics subject in the 5th and 6th graders elementary students. To carry out this study, the 5th and 6th graders recognition as learning mathematics subject was investigated by questionaire. The questionaire was analysed by using frequency and percentage. The 5th and 6th graders had difficulties in the hierarchical problem because mathematics is very systematic and hierarchical, and other had difficulties in studying mathematics because the explanation of the problem solving process in the textbook was not detailed. Others had difficulties in studying mathematics because of quick loaming progress, in applying the formulas and property of mathematics.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.830-833
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• 2005

SDM(Structural Dynamics Modification) is to improve dynamic characteristics of a structure, more specifically of a base structure, by adding or deleting auxiliary(modifying) structures. In this paper, I will focus on the optimal layout of the stiffeners which are attached to the plate to maximize 1st natural frequency. Recently, a new topology method was proposed by yamazaki. He uses growing and branching tree model. I modified the growing and branching tree model. The method is designated modified tree model. To expand the layout of stiffeners, I will consider non-matching problem. The problem is solved by using local lagrange multiplier without the mesh regeneration. Moreover The CMS(Component mode synthesis) method is employed to reduce the computing time of eigen reanalysis using reduced componet models.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.1
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• pp.361-378
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• 2012

Most of the current frequency hopping (FH) based dynamic spectrum access (DSA) methods concern a reactive channel access scheme with synchronous inter-channel spectrum sensing, i.e., FH is reactively triggered by the primary user (PU)'s return reported by spectrum sensing, and the PU channel to be switched to is assumed precisely just sensed or ready to be sensed, as if the inter-channel spectrum sensing moments are synchronous. However, the inter-channel spectrum sensing moments are more likely to be asynchronous, which risks PU suffering more interference. Moreover, the spectrum sensing is usually erroneous, which renders the problem more complex. To address this problem, we propose a proactive FH based DSA method against both erroneous spectrum sensing and asynchronous inter-channel spectrum sensing (moments). We term it as proactive DSA. The optimal FH sequence is obtained by dynamic programming. The complexity is also analyzed. Finally, the simulation results confirm the effectiveness of the proposed method.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.2 no.6
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• pp.299-311
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• 2008

The Radio Frequency IDentification (RFID) system is a contactless automatic identification system, which comprises readers and tags. In RFID systems, a reader collision occurs when there is interference in communication between one reader and the tags, due to the signals from other readers. The reader collision problem is considered as the fundamental problem affecting high density RFID reader installations. In this paper, we analyze the existing reader anti-collision algorithms. We also propose a pulse protocol-based reader anti-collision algorithm using slot occupied probability (SOP). The implementation of this improvement is simple, yet it effectively mitigates most reader collisions in dense reader mode, as shown in our simulation. That is, the proposed algorithm reduces the identification time, and increasesthe system throughput and system efficiency compared with the conventional reader anti-collision algorithms.

• Journal of the Korea Computer Industry Society
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• v.6 no.3
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• pp.429-436
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• 2005

The linear modulation method which has high spectrum efficiency when applying in mobile communication system, the problem occurs. In order to solve like this problem non-linearity characteristic of the power amplifier linearity against the method which it does it investigated. It used a design objection and it implemented the microwave power amplifier. The amplifier which it produces used the micro-strip line and when it imput power 13 dBm from center frequency, the possibility of getting the output power of 28 dBm.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.37.4-37
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• 2001

This paper presents a vibration-rejection control design for a magnetic suspension system which has strong non-linearity, open-loop unstable characteristics, high-order flexible modes, and parameter variations. The target plant to be controlled consists of a U-core electromagnet and a flexible rail. We describe the test rig and formulate the mathematical model and then we set up a control problem as the mixed sensitivity problem where the augmented plant is constructed with frequency weighting functions and the feedback controller is designed by using the H$\infty$ controller. The effectiveness of the designed controller for the magnetic suspension system with high-order flexible modes is validated and justified using several simulations. These results show that the magnetic suspension system is robustly stable against disturbance and gives the well-damped tracking performance ...

• 중국학논총
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• no.65
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• pp.23-38
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• 2020

The dictionary is the most important tool for every Chinese learner to confirm the meaning and usage of words. Therefore, accuracy of headword's interpretation in the dictionary is crucial. This study aims to discuss the accuracy and the adequacy of headwords' interpretation in the Chinese-Korean dictionary through the Chinese corpus and Baidu. The scope of this study are 3000 words in the D3H1 region. According to the research results, the main problems of the vocabulary in this region can be divided into three categories: the first is the problem of lexical interpretation, the second is the problem of missing interpretation, and the third is other problems. In the D3H1 area, there are a total of 719 low-frequency vocabularies, and 54 headword's interpretations are not accurate or appropriate. This study is a detailed investigation and analysis of the problems of these 54 vocabularies.

• International Journal of Internet, Broadcasting and Communication
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• v.13 no.2
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• pp.166-172
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• 2021

The purpose of this study is to identify the impact of informatization minds of college students majoring in sports on information development efforts and academic achievement. Accordingly, a survey was conducted on 200 college students majoring in physical education at D University, and 197 students were selected as the final effective samples. Data processing was conducted using SPSS 23 for frequency analysis, reliability analysis, correlation analysis, and regression analysis. The results are as follows: First, recognition of the necessity of informatization education, a subfactor of the informatization mind, has a positive impact on informatino development efforts. Second, recognition of the necessity of informatization education, understanding and utilization of informatization concepts among sub-factors of informatization minds have a positive impact on the major learning achievement. Third, all the conversational factors in the informatization mind have a positive impact on study problem resolution. Fourth, information development efforts have a positive impact on the major learning achievement and the study problem resolution. Therefore, efforts are needed to increase the information mindset of college students major in sports.

• The Journal of the Acoustical Society of Korea
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• v.20 no.2E
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• pp.9-16
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• 2001

A psychoacoustic model based noise shaping method which shapes the noise in the frequency domain is proposed, where its presence with a host signal will not be perceptually noticeable. The derivation of imperceptible noise levels from the masking thresholds of the signal involves a deconvolution associated with the spreading function in the psychoacoustic model, which results in an ill-conditioned problem. In this paper, the problem is formulated as a constrained optimization, and it is demonstrated that the solution provides noise shaping where the noise excitation level conforms to the masking thresholds of the signal, and thus the noises embedded in the signal will not be perceived by human ear.