• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.49.2-49
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• 2002

This paper describes the configuration of a multi-agent system that can recognize human intentions. This system constructs ontologies of human intentions and enables knowledge acquisition and sharing between intelligent agents operating in different environments. This is achieved by using a bi-directional associative memory network. The process of intention recognition is based on fuzzy association inferences. This paper shows the process of information sharing by using ontologies. The purpose of this research is to create human-centered systems that can provide a natural interface in their interaction with people.

• 한국방재학회:학술대회논문집
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• 2010.02a
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• pp.66.2-66.2
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• 2010

장대 케이슨 방파제에 작용하는 다방향 불규칙파랑의 파력 평활화 계수를 계산하였다. 다방향 불규칙파랑의 주파수 스펙트럼으로는 Bretschneider-Mitsuyasu 스펙트럼을 사용하였고, 방향 스펙트럼은 Mitsuyasyu 타입의 스펙트럼을 적용하였다. 계산 결과 단일 케이슨의 길이가 길수록, 주파향의 입사각이 클수록 평활화 계수는 감소하였다. 다양한 에 대해서도 계산하였으며, 가 클수록 평활화계수는 규칙파와 비슷한 경향을 보였다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1997.10a
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• pp.339-344
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• 1997

Samsung Ltd. has developed a new-type cab mount for specific use on construct ion machinery subjected to strong vibration and multi-directional impact force. These all make it possible to achieve an excellent damping effect over a wide frequency range against large amplitude vibration as well as excellent insulation against small-amplitude vibration. This new mount make lower vibration and noise levels while increasing riding comfort at the same time. Characteristics of Cab mount were optimized through computer simulation, advanced bench testing, ODS testing, and a real equipment offroad testing.

• Journal of the Microelectronics and Packaging Society
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• v.11 no.2 s.31
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• pp.43-47
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• 2004

A coupler or divider is a microwave passive component used for power coupling or dividing. Regarding the trend of current telecommunication systems monolithic integration of passive components is highly desirable. In this study by the LTCC(Low temperature co-fired ceramics) technology a 2012 size type dual band coupler with multi-layer structure was fabricated. To achieve the desired coupling values for both DCS and EGSM bands, broad side coupled patterns were used with multi-layer structure. Its characteristics such as coupling, insertion loss, isolation and directivity values were measured and compared with simulation results.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.12
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• pp.6017-6037
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• 2017

In a multi-resolution image encoding system, the image is encoded into a single file as a layer of bit streams, and then it is transmitted layer by layer progressively to reduce the transmission time across a low bandwidth connection. This encoding scheme is also suitable for multiple decoders, each with different capabilities ranging from a handheld device to a PC. In our previous work, we proposed an edge adaptive hierarchical interpolation algorithm for multi-resolution image coding system. In this paper, we enhanced its compression efficiency by adding three major components. First, its prediction accuracy is improved using context adaptive error modeling as a feedback. Second, the conditional probability of prediction errors is sharpened by removing the sign redundancy among local prediction errors by applying sign flipping. Third, the conditional probability is sharpened further by reducing the number of distinct error symbols using error remapping function. Experimental results on benchmark data sets reveal that the enhanced algorithm achieves a better compression bit rate than our previous algorithm and other algorithms. It is shown that compression bit rate is much better for images that are rich in directional edges and textures. The enhanced algorithm also shows better rate-distortion performance and visual quality at the intermediate stages of progressive image transmission.

• Journal of Power Electronics
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• v.16 no.2
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• pp.610-620
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• 2016

The compound active clamp zero voltage soft switching (CACZVS) three-phase power factor correction (PFC) converter has many advantages, such as high efficiency, high power factor, bi-directional energy flow, and soft switching of all the switches. Triple closed-loop PI controllers are used for the three-phase power factor correction converter. The control objectives of the converter include a fast transient response, high accuracy, and unity power factor. There are six parameters of the controllers that need to be tuned in order to obtain multi-objective optimization. However, six of the parameters are mutually dependent for the objectives. This is beyond the scope of the traditional experience based PI parameters tuning method. In this paper, an improved chaotic particle swarm optimization (CPSO) method has been proposed to optimize the controller parameters. In the proposed method, multi-dimensional chaotic sequences generated by spatiotemporal chaos map are used as initial particles to get a better initial distribution and to avoid local minimums. Pareto optimal solutions are also used to avoid the weight selection difficulty of the multi-objectives. Simulation and experiment results show the effectiveness and superiority of the proposed method.

• Structural Engineering and Mechanics
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• v.72 no.2
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• pp.181-190
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• 2019

Topology optimization of structures seeking the best distribution of mass in a design space to improve the structural performance and reduce the weight of a structure is one of the most comprehensive issues in the field of structural optimization. In addition to structures stiffness as the most common objective function, frequency optimization is of great importance in variety of applications too. In this paper, an efficient multi-objective Bi-directional Evolutionary Structural Optimization (BESO) method is developed for topology optimization of frequency and stiffness in continuum structures simultaneously. A software package including a Matlab code and Abaqus FE solver has been created for the numerical implementation of multi-objective BESO utilizing the weighted function method. At the same time, by considering the weaknesses of the optimized structure in single-objective optimizations for stiffness or frequency problems, slight modifications have been done on the numerical algorithm of developed multi-objective BESO in order to overcome challenges due to artificial localized modes, checker boarding and geometrical symmetry constraint during the progressive iterations of optimization. Numerical results show that the proposed Multiobjective BESO method is efficient and optimal solutions can be obtained for continuum structures based on an existent finite element model of the structures.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.24 no.3
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• pp.109-114
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• 2024

The effect of inter-channel coupling in multi-channel monopulse receiver is expected to increase by miniaturization trend of receiver. Therefore, in this paper, calibration method is proposed to compensation for inter-channel coupling in receiver of monopulse radar. And it can prevent distortion of angle information of target. Hardware configuration that consists of switch, directional coupler, matched load, ADC(Analog to Digital Converter), signal source of calibration is proposed to calibration. Total nine scattering parameters are obtained by controlling the switch and signal source of calibration. After that, method for restoring the undistorted signal is proposed using the mathematical relationship between the monopulse signal output from the antenna and the monopulse signal passing through the multi-channel receiver in the presence of inter-channel coupling.

• Proceedings of the KIPE Conference
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• 2011.11a
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• pp.73-74
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• 2011

Phase-shedding, one famous technology for multi-phase converters, is implemented in a bi-directional multi-phase converter for ESS. It reduces active operating modules at light load to compensate efficiency. Shedding point, the load level where the converter changes the number of active modules, is important factor that affects the effect of phase-shedding. Loss analysis is done for determining shedding point. Phase-shedding hysteresis is applied so that excessive phase transition is avoided. This paper proposes shedding point correction where the shedding point is adaptively corrected by calculating a new shedding point.

• Journal of Ocean Engineering and Technology
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• v.17 no.4
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• pp.1-7
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• 2003

A virtual reality technology for multipurpose numerical simulation is developed to reproduce and investigate a variety of ocean environmental problems in a 3D Numerical Wave Tank(NWT). The governing equations for solving incompressible fluid motion are Navier-Stokes equation and continuity equation. The Marker-Density function technique is adopted to implement the fully nonlinear freesurface kinematic condition. The marine environmental situations, i.e., waves, currents, etc., are reproduced by use of multi-segmented wavemakers on the basis of the so-called ″snake-principle″. In this paper, some numerical reproduction techniques for regular, and irregular waves, multi-directional waves, Bull's-eye wave. wave-current, and solitary wave are presented, and a model test in motion with large amplitude of roll angle is conducted in the developed 3D-NWT, using a overlaid grid system.