• 한국생산제조학회지
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• 제26권3호
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• pp.313-319
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• 2017

This study presents a genetic algorithm (GA) to design a PID controller systematically for an inchworm operated by piezoelectric actuators. The performance index considering overshoot and settling time is adopted to search an optimal PID gain using GA. The piezoelectric actuator shows nonlinear characteristics including hysteresis and residual displacement. The PID feedback system combined with an integrator is used to improve the ability of tracking the complex input signals and suppressing the steady state error. The PID controller tuned by GA can track the various motion contours effectively. However, the PID controller shows an improper residual vibration under the application of high-frequency square input. The input shaper combined with the feedback system can overcome this limitation of the PID controller.

• Structural Engineering and Mechanics
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• 제31권1호
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• pp.93-112
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• 2009

In this study seismic analyses of steel structures were carried out to examine the effect of ground motion characteristics and structural properties on energy demands using 100 earthquake ground motions recorded in different soil conditions, and the results were compared with those of previous works. Analysis results show that ductility ratios and the site conditions have significant influence on input energy. The ratio of hysteretic to input energy is considerably influenced by the ductility ratio and the strong motion duration. It is also observed that as the predominant periods of the input energy spectra are significantly larger than those of acceleration response spectra used in the strength design, the strength demand on a structure designed based on energy should be checked especially in short period structures. For that reason framed structures with buckling-restrained-braces (BRBs) were designed in such a way that all the input energy was dissipated by the hysteretic energy of the BRBs, and the results were compared with those designed by conventional strength-based design procedure.

• 한국소음진동공학회논문집
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• 제18권7호
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• pp.756-763
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• 2008

This paper presents an inchworm with three piezoelectric actuators. The dynamic stiffness of the inchworm is generally low compared to its driving condition, so mechanical vibration may degenerate the motion accuracy of the inchworm. The dynamic model of inchworm is identified by curve fitting technique based on the experimental frequency response function. For the precision motion control and low residual vibration of inchworm, driving input signal is designed by using cycloid step input and LQG control technique. Experimental result shows that proposed input shaping method is applicable effectively to the inchworm.

• 산업기술연구
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• 제19권
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• pp.173-178
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• 1999

In many areas of technology there are machines and systems controllable in up to six degrees of freedom. Helicopters and underwater vehicles, industrial robots are among the first representatives of this category. They need six degrees of freedom in order to move and orient within their workspace. An even broader and more explosively growing area is 3D computer graphics and virtual environment. In this work, functions of 3D input device are described and two types of commercial 3D input device are presented. Then, a preliminary experiment of a low cost 6 axis force/moment sensor is presented that can also be sued as a 3D input device. A low cost force/moment sensor and its application in robot teaching experiment is described. It computes the direction of 3 components of the force and 3 components of the moment applied by human holding the sensor by hand. The concept is shown by an experiment where the tool position and orientation of a robot in 3 dimensional space is controlled by the proposed sensor.

• 한국지진공학회논문집
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• 제9권3호
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• pp.59-68
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• 2005

에너지 설계법은 지진에 의해 누적된 손상과 구조물의 이력거동에 의한 영향을 직접적으로 고려할 수 있기 때문에 현행 내진설계 기준보다 더 합리적이다. 그러나 지반운동과 구조물 특성에 따른 에너지 응답에 대한 관련 연구자들의 합의가 아직 도출되지 않고 있다. 따라서 본 연구에서는 에너지 요구에 대한 지진하중과 구조물 특성의 영향을 다른 지반조건에서 계측된 100개의 지진기록을 이용하여 평가하고 기존 연구결과와 비교하였다. 해석 결과에 따르면 연성비와 지반조건은 입력에너지에 상당한 영향을 주는 것으로 나타났다. 입력에너지에 대한 이력에너지비는 연성비, 감쇠비와 강한 지진파의 지속시간에 많은 영향을 받았지만 지반조건에 따른 변화는 작았다.

• ETRI Journal
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• 제37권2호
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• pp.406-416
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• 2015

Timing plays a key role in expressing the qualitative aspects of a character's motion; that is, conveying emotional state, personality, and character role, all potentially without changing spatial positions. Temporal editing of locomotion style is particularly difficult for a novice animator since observers are not well attuned to the sense of weight and energy displayed through motion timing; and the interface for adjusting timing is far less intuitive to use than that for adjusting pose. In this paper, we propose an editing system that effectively captures the timing variations in an example locomotion set and utilizes them for style transfer from one motion to another via both global and upper-body timing transfers. The global timing transfer focuses on matching the input motion to the body speed of the selected example motion, while the upper-body timing transfer propagates the sense of movement flow - succession - through the torso and arms. Our transfer process is based on key times detected from the example set and transferring the relative changes of angle rotation in the upper body joints from a timing source to an input target motion. We demonstrate that our approach is practical in an interactive application such that a set of short locomotion cycles can be applied to generate a longer sequence with continuously varied timings.

• 인터넷정보학회논문지
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• 제15권4호
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• pp.9-20
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• 2014

대상의 동작을 잘 예측하는 것은 사회적 상호작용과 의사결정 컨텍스트 이해의 핵심이다. 본 연구는 동작 인식 과정에서 인간 뇌 시각인지 과정을 모방한 방법으로 관절 동작의 동작 순서 패턴을 학습하는 컴퓨팅 모델을 제안하였다. 제안 방법의 핵심은 뇌에서 동작 인지 자극을 처리하는 신경생리학적 IT, MT, STS의 피질 기능과 특정 시각 신경 회로 네트워크 기능을 모방하여 비지도 방법으로 동작 순서를 학습한 후 동작을 예측, 인식하는 것이다. 실험을 통해 제안 모델이 어떻게 연속적으로 입력되는 비디오에서 의미있는 동작 스냅샷 뿐 아니라 중요한 동작 패턴을 자동으로 선택하는 지를 제시하였다. 이 핵심 움직임은 학습 네트워크가 정적 시점에서 정지 영상에 함축된 동작을 인식하는지를 증명하는데 이용하는 관절 자세이다. 또한 STS 피질 영역에서 어떻게 정지와 움직임 입력을 통합하는지를 모방하여 학습하고, 학습한 피드백 연결이 차후 동작의 입력 순서를 어떻게 예측하는지를 제시하였다. 네트워크 시뮬레이션을 통해 동작 인식에 대한 제안 모델의 우수성을 입증하였다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 춘계 학술발표회 논문집
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• pp.1134-1139
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• 2005

Seismic motion amplification owing to the input motion level at bedrock is one of the important topics to understand various geomaterials behavior. The extremely valuable borehole records at Port Island were obtained during the 1995 Hyogoken Nanbu Earthquake and also before and after the main event. In this study, the seismic motion amplification at the soft reclaimed ground was discussed. Comparison of measured records with numerical simulation results were made with focus on seismic motion amplification characteristics at the soft reclaimed ground.

• 한국항행학회논문지
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• 제13권4호
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• pp.503-508
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• 2009

본 논문에서는 특정인(장애인, 재활치료자, 고령자 등)들이 수월하게 컴퓨터를 사용 할 수 있도록 하기 위한 손동작 인식형 보조 입력장치를 설계하였다. 입력장치는 3차원 공간에서 손 동작 인식을 위해 자이로 센서를 사용하였고, 통신 대역은 무선 RF 2.4GHz 대역에서 신호를 송 수신 하도록 하였다. 제작된 보드는 자이로 모듈, RF 통신 모듈, MCU, USB 단자 등으로 구성되었다. 동작인식 실험결과, 마우스 기반의 커서 이동 및 프로그램 제어 등이 설계 규격대로 수행됨을 확인 하였다.

• Earthquakes and Structures
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• 제8권5호
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• pp.957-976
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• 2015

Recently, two energy-based response parameters, i.e., the absolute and the relative elastic input energy equivalent velocity, have been receiving a lot of research attention. Several studies, in fact, have demonstrated the potential of these intensity measures in the prediction of the seismic structural response. Although some ground motion prediction equations have been developed for these parameters, they only provide marginal distributions without information about the joint occurrence of the spectral values at different periods. In order to build new prediction models for the two equivalent velocities, a large set of ground motion records is used to calculate the correlation coefficients between the response spectral values corresponding to different periods and components of the ground motion. Then, functional forms adopted in models from the literature are calibrated to fit the obtained data. A new functional form is proposed to improve the predictions of the considered models from the literature. The components of the ground motion considered in this study are the two horizontal ones only. Potential uses of the proposed equations in addition to the prediction of the correlation coefficients of the equivalent velocity spectral values are shown, such as the prediction of derived intensity measures and the development of conditional mean spectra.