• Journal of Institute of Control, Robotics and Systems
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• v.8 no.1
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• pp.15-20
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• 2002

An electro-hydraulic manipulator using hydraulic actuators has many nonlinear elements, and its parameter fluctuations are greater than those of an electrically driven manipulator. So it is relatively difficult to realize not only stable contact work but also accurate force control for the automatic assembly tasks using hydraulic manipulators. In this manuscript, we applied a compliance control, which is based on the position control by a disturbance observer for our manipulator system. A reference trajectory modification method is proposed in order to achieve accurate force control even though the stiffness and the position of the environment change. Experimental results show that highly robust force tracking by a 6-link electro-hydraulic manipulator could be achieved under various environment conditions. The proposed force control algorithm is applied to the approaching of bolt and the wrenching of nut tasks as one typical task in the maintenance work of live power electric line and is experimentally confirmed very effective for the task.

• The Journal of the Acoustical Society of Korea
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• v.16 no.1
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• pp.33-38
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• 1997

In this paper, we analyzed the resolution of tomographic images which can be obtained with Scanning Tomographic Acoustic Microscope(STAM) utilizing the acousto-optic effect. To realize this, lateral and depth resolutions of both ultrasonic transducer and specimen rotating device are obtained by using BFP tomographic reconstruction algorithm. Simulation results show that both rotating devices have a good depth resolution of $1.5{\lambda}$. For the lateral resolution, the specimen rotating device produces $0.53{\lambda}$ in the x and y directions and the transducer rotating device produces $0.56{\lambda}$ and $0.70{\lambda}$ in the x and y directions respectively. These results imply that the specimen rotating device is more suitable for STAM system construction.

• Journal of the Society of Naval Architects of Korea
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• v.42 no.5 s.143
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• pp.534-541
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• 2005

Until now, Korean shipyards have accumulated a great amount of data. But they do not have appropriate tools to utilize the data in practical works. Engineering data contains experts' experience and know-how in its own. It is very useful to extract knowledge or information from the accumulated existing data by using data mining technique This paper treats an evolutionary computation based on genetic programming (GP), which can be one of the components to realize data mining. The paper deals with linear models of GP for the regression or approximation problem when given learning samples are not sufficient. The linear model, which is a function of unknown parameters, is built through extracting all possible base functions from the standard GP tree by utilizing the symbolic processing algorithm. In addition to a standard linear model consisting of mathematic functions, one variant form of a linear model, which can be built using low order Taylor series and can be converted into the standard form of a polynomial, is considered in this paper. The suggested model can be utilized as a designing tool to predict design parameters with small accumulated data.

• Proceedings of the KIEE Conference
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• 2000.07a
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• pp.394-396
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• 2000

This paper presents a new algorithm for the allocation of the reliability level of composite power system under deregulated electricity market. Under deregulated electricity market, it is required to establish a methodology that can evaluate supply cost and supply reliability of each demand to realize the available priority service reflected a preference of each customer. In this study, a concept of reliability differentiated electricity service as priority service to keep reliability of particular customer within a desirable level is proposed on HLII under deregulated competitive electricity market. The uncertainties of not only generators but also transmission lines are considered for the reliability evaluation in this study. The characteristics and effectiveness of this methodology are illustrated by the case studies on MRBTS and IEEE-RTS.

• Journal of Satellite, Information and Communications
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• v.6 no.2
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• pp.78-83
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• 2011

In this paper, we propose a computationally efficient early stopping method to reduce the average number of iterations. The conventional early stopping methods have too much computational complexity to compute the stopping criterion. Thus, only the hard decision based early stopping method is suitable to realize the hardware of LDPC decoder. However, this method also can increase the computational complexity of LDPC decoder. The proposed method can effectively reduce the computational complexity of stopping criterion as we do not compute hard decision, and we combine the stopping criterion with horizontal shuffling scheduling decoding scheme. The simulation results show that a new early stopping method achieves acceptable bit error rate performance also reduces the average number of iterations.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.2
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• pp.228-235
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• 2002

Differentiated services network (DiffServ) aims to provide the same service to a group of connections that have similar Quality of Service requirements. One of the essential function to realize DiffServ is the traffic conditioning mechanisms to support the required services. The paper proposes the enhanced traffic conditioning mechanism which alleviates a bias against reserved bandwidth size. The simulation results show that the new mechanism is rather insensitive of size of reserved bandwidth, and performs better both in terms of throughput assurance and fair distribution of excess bandwidth in case of well-provisioned and over-provisioned network environment.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.9
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• pp.833-839
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• 2011

This paper has suggested a technique for measuring VSWR at 1.8 GHz band for various modulated signals. By using directional coupler the power of incident and reflected wave is measured, and in order to minimize the size and cost of the measuring circuit, a SPDT(Single Pole Double Throw) switch is adopted to realize the circuit with just one detector and one A/D(Analog to Digital) converter. MCU(Micro Control Unit) is used to calculate the voltage reflection coefficient and VSWR, and the measured VSWR error has improved by approximately 0.2 with applying a simple bubble sorting algorithm to reduce the measurement error, the MCU process time and load.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.12
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• pp.6116-6132
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• 2017

The proxy re-encryption allows an intermediate proxy to convert a ciphertext for Alice into a ciphertext for Bob without seeing the original message and leaking out relevant information. Unlike many prior identity based proxy re-encryption schemes which are based on the number theoretic assumptions such as large integer factorization and discrete logarithm problem. In this paper, we first propose a novel identity based proxy re-encryption scheme which is based on the hardness of standard Learning With Error(LWE) problem and is CPA secure in the standard model. This scheme can be reduced to the worst-case lattice hard problem that is able to resist attacks from quantum algorithm. The key step in our construction is that the challenger how to answer the private query under a known trapdoor matrix. Our scheme enjoys properties of the non-interactivity, unidirectionality, anonymous and so on. In this paper, we utilize primitives include G-trapdoor for lattice and sample algorithms to realize simple and efficient re-encryption.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.36C no.11
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• pp.84-91
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• 1999

In this paper, we could analyze the comparison with applied WFM to the quantization triangularity fuzzy function and triangularity Fuzzy function. In order to improve on a fault which not remove completely noise included image according to a peculiarity of noise, we got to realize FDNN of the high speed weight eliminating noise included image, minimizing the lost of information, obtaining information of suitability owing to applied Fuzzy Algorithm to DBNN of a hierarchical structure. We could analyze the comparison with a power of WFM and FDNN using simulation We could find to superiority the proposed FDNN )n a result which was the comparison of MSE for the boats image.

• Journal of Electrical Engineering and Technology
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• v.13 no.2
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• pp.989-997
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• 2018

Massive event stream brings us great challenges in its volume, velocity, variety, value and veracity. Picking up some valuable information from it often faces with long detection time, high memory consumption and low detection efficiency. Aiming to solve the problems above, an efficient complex event detection method based on NFA_HTS (Nondeterministic Finite Automaton_Hash Table Structure) is proposed in this paper. The achievement of this paper lies that we successfully use NFA_HTS to realize the detection of complex event from massive RFID event stream. Specially, in our scheme, after using NFA to capture the related RFID primitive events, we use HTS to store and process the large matched results, as a result, our scheme can effectively solve the problems above existed in current methods by reducing lots of search, storage and computation operations on the basis of taking advantage of the quick classification and storage technologies of hash table structure. The simulation results show that our proposed NFA_HTS scheme in this paper outperforms some general processing methods in reducing detection time, lowering memory consumption and improving event throughput.