• Journal of the Earthquake Engineering Society of Korea
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• v.9 no.1 s.41
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• pp.51-59
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• 2005

Magnetorheological(MR) dampers are one of the most promising semi active control devices, because they have advantages such as small power requirement, reliability, and low price to manufacture. To reduce the responses of structures with MR dampers, a control system including power supply, controller, and sensors is required. However, when a mount of MR dampers are used to a large?scale civil structure such as cable stayed bridges, the control system becomes complex. Therefore, it is not easy to install and maintain the MR damper based control system. To resolve above difficulties, This paper proposes a smart passive system that consists of a MR damper and an electromagnetic induction(EMI) system. According to the Faraday’s law of induction, EMI system that is attached to the MR damper produces electric energy. The produced energy is supplied to the MR damper. Thus, the MR damper with EMI system does not require any power at all. Furthermore, the induced electric energy is proportional to external loads like earthquakes, which means the MR damper with EMI system is adaptable to external loads without any controller and corresponding sensors. Therefore, it is easy to build up and maintain the proposed smart passive system.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.6
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• pp.1381-1388
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• 1993

This paper presents a method for the simultaneous optimal design of structural and control systems. Sensitivities of performance index with respect to structural design variables are analyzed. The structural design variables are optimized to minimize the performance index by use of conjugate gradient method. The method is applied to a half model of an active vehicle suspension system with elastic body moving on a randomly profiled road. The suspension control force of an optimally controlled system in the presence of measurement errors are calculated by use of linear quadratic Gaussian control theory and Kalman filter theory. The performance index contains ride comfort, road holding and working space of suspension. The structural design variables taken are stiffness, daming properties and the position of the suspension system. The random road profile considered as colored noise is shaped from white noise by use of shaping filter. The performance of an optimal simultaneous structure/control system is compared with that of an optimal controlled system.

• Journal of KIISE
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• v.42 no.11
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• pp.1397-1403
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• 2015

A named entity(NE) dictionary is an important resource for the performance of NE recognition. However, it is not easy to construct a NE dictionary manually since human annotation is time consuming and labor-intensive. To save construction time and reduce human labor, we propose a semi-automatic system for the construction of a NE dictionary. The proposed system constructs a pseudo-document with Wiki-categories per NE class by using an active learning technique. Then, it calculates similarities between Wiki entries and pseudo-documents using the BM25 model, a well-known information retrieval model. Finally, it classifies each Wiki entry into NE classes based on similarities. In experiments with three different types of NE class sets, the proposed system showed high performance(macro-average F1-score of 0.9028 and micro-average F1-score 0.9554).

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.8
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• pp.758-764
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• 2015

This paper describes the pattern synthesis of array antenna which conforms to a metallic curved surface formed by the rotation of a quadratic function by using EAGA(Enhanced Adaptive Genetic Algorithm). Three rotated-type conformal surfaces are realized by changing the coefficient of the quadratic function and the pattern of each conformal array antenna is synthesized. In order to reduce the overall time of pattern synthesis, the transformed active element pattern obtained by the active element pattern of the 2-dimensional planar array using Euler angles rotation is utilized instead of the active element pattern of the 3-dimensional conformal array antenna itself. To verify validity of the proposed synthesis procedure, the synthesized patterns using EAGA are compared with those obtained by MWS.

• The Journal of the Acoustical Society of Korea
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• v.31 no.4
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• pp.235-243
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• 2012

This paper studies characteristics and causes of sound, and many others by distinguishing passivity and activity of the cases of a dog vocalizing human's words. As a result of the previous cases of vocalization of human's words, the dog was able to understand characteristics of a host's voice and imitate the sound using his own vocal organs. This is the case of passive vocalization accompanied by temporary voice imitation without a function of communication. On the contrary, as a consequence of the recently reported case in which a dog vocalizes such words as "Um-ma" and "Nu-na-ya," it shows the vocalization pattern clearly distinguished from the prior cases. The given dog repeatedly vocalizes pertaining words in an active manner according to circumstances and plays a role of fundamental communication and interaction with its host. The reason why the dog can vocalize the man's words actively is determined to be that the dog has a high level of intelligence and intimacy with its host, that people react actively to its pertaining pronunciation, and so forth. The following results can be used for the study that investigates animals' sound with vocalization possibility and language learning feasibility.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.3
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• pp.1459-1466
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• 2013

Recently, various types of three-dimensional cameras have been used to analyze surrounding environments. In this paper, we suggest a mechanism of adaptively switching active and passive cameras of hybrid cameras, which can extract 3D image information more accurately. The suggested method first obtains brightness and texture features representing the environment from input images. It then adaptively selects active and passive cameras by generating rules that reflect the extracted features. In experimental results, we show that a hybrid 3D camera consisting of passive and active cameras is set up and the proposed method can effectively choose appropriate cameras in the hybrid camera and make it possible to extract three dimensional information more accurately.

• The Journal of the Acoustical Society of Korea
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• v.38 no.5
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• pp.522-533
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• 2019

The compressive sensing model for range-Doppler estimation can be expressed as an under-determined linear system y = Ax. To find the solution of the linear system with the compressive sensing method, matrix A should be sufficiently incoherent and x to be sparse. In this paper, we propose a transmission waveform design method that maintains the bandwidth required by the sonar system while lowering the mutual coherence of the matrix A so that the matrix A is incoherent. The proposed method combines two methods of optimizing the sensing matrix with the alternating projection and suppressing unwanted frequency bands using the DFT (Discrete Fourier Transform) matrix. We compare range-Doppler estimation performance of existing waveform LFM(Linear Frequency Modulated) and designed waveform using the matched filter and the compressive sensing method. Simulation shows that the designed transmission waveform has better detection performance than the existing waveform LFM.

• The Journal of the Acoustical Society of Korea
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• v.40 no.5
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• pp.401-407
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• 2021

The continuous active sonar technology is effective for detecting and tracking targets because of short target revisiting rate. Generalized Sinusoidal Frequency Modulation (GSFM) pulses suitable for continuous active sonar systems are known to be capable of obtaining high time-bandwidth product while maintaining the orthogonality between pulses. However, it is unknown how to calculate an appropriate length of time to correlate received GSFM pulses in the presence of a target with acceleration. In this paper, we propose a method to calculate the appropriate time length based on the correlation when matching the received signal in the continuous active sonar system using GSFM pulse. The proposed method calculates the correlation according to the acceleration of the target and calculates the signal processing length according to the correlation. It is shown that stable detection performance can be obtained when the signal processing length calculated by the proposed method through the level of the sidelobe is applied.

• 한국정보교육학회:학술대회논문집
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• 2006.01a
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• pp.107-112
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• 2006

본 연구는 인지적 학습효과가 높아지고 자아 존중감과 협동심을 키울 수 있는 JigsawIII모형을 ICT 소양교육에 적용하는 방안에 대한 연구이다. JigsawIII를 토대로 ICT 소양교육의 이론과 기능분야를 학습하도록 학습환경과 학습절차를 구성하고 실제 현장에 적용하여 실험집단에 JigsawIII 모형을 실시하고, 통제집단에 전통학습방법을 실시하였다. 연구의 결과 이론 학습에서는 실험집단과 통제집단의 학습효과가 비슷하였으나, 기능학습에서는 JigsawIII를 적용한 실험집단이 평균점수의 검증결과가 더 높게 나타났으며, 통계적으로도 p<.05 수준에서 유의미한 것으로 나타났다. ICT 소양교육이 실생활에서 응용할 수 있는 ICT 지식을 익히고 능동적으로 활용하도록 하는 것에 그 목적이 있으므로 JigsawIII모형 ICT 교육에 활용한다면 긍정적인 교육적 효과를 이루어낼 수 있을 것이다.

• Proceedings of the Korean Information Science Society Conference
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• 2005.11a
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• pp.184-186
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• 2005

본 논문은 시간 제약 조건을 갖는 컨텍스트(상황)에 대한 분산적 탐지 기법(PROCON)을 제안한다. 수집한 데이터를 베이스 스테이션으로 모아 컨텍스트의 발생 여부를 결정하는 기존의 중앙집중 기법과 달리 PROCON은 네트워크 내에서 능동적, 분산적 방식으로 센서 노드 간의 협업을 통하여 컨텍스트를 결정한다. 따라서, 컨텍스트의 발생여부 탐지와 이에 대한 대응(Actuation)이 베이스 스테이션에 독립적으로 네트워크 내에서 모두 이루어진다. 본 논문은 다양한 상황구성에 대한 시뮬레이션을 통해 PROCON의 분산 상황방식이 기존의 중앙집중 방식에 비해 상당한 에너지 절약과 서비스 신뢰성(reliability) 향상을 가져온다는 것을 보인다.