• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 1991년도 한국자동제어학술회의논문집(국제학술편); KOEX, Seoul; 22-24 Oct. 1991
• /
• pp.1681-1686
• /
• 1991

In robotics and other fields of engineering, techniques for artificial reality or virtual reality are focused on and studied extensively, e.g., virtual existence for tele-operator systems in robotics, and virtual reality of designed objects in architecture. In order to realize the system we should create physical stimulations according to internal models created by experiences in a human brain. The internal model does not have to have direct connections to the real world, however, the stimulation must be signals such that the internal model are retrieved in a human brain. In this paper we propose a technique for tele-virtual reality of dynamic mechanical models, which means that one dynamic mechanical model can be shared by peoples in distant places. Since a stability issue due to time delays arises in the system, we employed a scattering technique developed for a tele-operator system and a kind of passive adaptive controllers. Furthermore, restrictions due to a simple digital implementation of the scattering transformation are discussed and some conditions for stability are shown. The proposed method is applied to a remote tug of war system and the effectiveness is verified.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2005년도 춘계학술대회논문집
• /
• pp.221-226
• /
• 2005

In this paper, a dynamic model for the rotor shaft-coupling-blade system is developed. The blades are attached to a disk and driven by an electric motor shaft which is flexible in torsion. We assumed that the shaft torsional flexibility is lumped in the flexible coupling which is usually adopted in rotor systems. The Lagrangian approach with the small deformation theory for both blade-bending and shaft-torsional deformations is employed for developing the equation of the motion. The assumed modes method is used for estimating the blade transverse deflection. The numerical results highlight the effects of both structural damping of the system and the torsional stiffness of the flexible coupling to the dynamic response of the blade. The results showed strong coupling between the blade bending and shaft torsional vibrations in the form of inertial nonlinearif, stiffness hardening and softening.

• Journal of Electrical Engineering and Technology
• /
• 제10권4호
• /
• pp.1389-1399
• /
• 2015

This research suggests maximum power point tracking (MPPT) for the solar photovoltaic (PV) power scheme using a new constant voltage (CV) fractional order incremental conductance (FOINC) algorithm. The PV panel has low transformation efficiency and power output of PV panel depends on the change in weather conditions. Possible extracting power can be raised to a battery load utilizing a MPPT algorithm. Among all the MPPT strategies, the incremental conductance (INC) algorithm is mostly employed due to easy implementation, less fluctuations and faster tracking, which is not only has the merits of INC, fractional order can deliver a dynamic mathematical modelling to define non-linear physiognomies. CV-FOINC variation as dynamic variable is exploited to regulate the PV power toward the peak operating point. For a lesser scale photovoltaic conversion scheme, the suggested technique is validated by simulation with dissimilar operating conditions. Contributions are made in numerous aspects of the entire system, including new control algorithm design, system simulation, converter design, programming into simulation environment and experimental setup. The results confirm that the small tracking period and practicality in tracking of photovoltaic array.

• 대한기계학회논문집
• /
• 제18권5호
• /
• pp.1158-1168
• /
• 1994

For BEM analyses of the impact problems of dissimilar materials, the connected multi-region method using perfect bonded conditions on the interface boundaries was added to two-dimensional Laplace transformed-domain BEM program for a single region analysis. It was confirmed that the BEM results of impact problems of a single-region and multi-regions for a homogeneous isotropic material are agreed well. The two-dimensional Laplace transformed-domain BEM program combined with connected multi-region method was applied to analyse several impact problems of dissimilar materials. Also the feasibility of BEM impact analyses was investigated for dissimilar materials by the analysis of the BEM results for impact problems of dissimilar materials in terms of physical aspects. As for an application, the two-dimensional Laplace transformed BEM concerning impact problems of cracks at the interface of dissimilar materials and the determinating process of the dynamic stress intensity factors by extrapolation method are presented in this paper.

• 대한수학교육학회지:학교수학
• /
• 제15권4호
• /
• pp.957-973
• /
• 2013

본 연구에서는 중학교 3학년 수학영재 학생들이 비유클리드 쌍곡원반모형에서 정삼각형 테셀레이션을 구성하는 활동을 하면서 나타나는 사고과정을 분석하였다. 역동적 기하환경인 poincare disk. gsp 파일에서 테셀레이션을 구성하기 위해 쌍곡평면에서 도형과 변환에 대한 학습을 하였다. 쌍곡선분의 특징을 탐구하고 도형인 정삼각형의 작도와 반전 변환을 학습 한 후 작도 과정을 반복한 후 쌍곡평면에서 테셀레이션이 가능하게 되는 조건을 탐구하는 과제를 해결하였다. 학생들은 이러한 과제를 해결하며 다양한 전략적 사고과정이 나타났고, 비유클리드 기하체계를 인지하는 경험을 할 수 있었다.

• 한국실내디자인학회논문집
• /
• 제19권5호
• /
• pp.83-94
• /
• 2010

Conventionally, ornament has developed around linear thinking based on Euclidean geometry, and been explained as simple and lucid natural Euclidean geometrical phenomena. The modular arrangement with vertical, horizontal and diagonal grids has been an organizing principle of classical ornament, but in digital era ornament is found not to be explained only with the principle of traditional arrangement due to the seemingly irregular complex forms. In that sense, this study presents the concept of digital ornament and examined the backgrounds of ornament in digital age, that are complex system and non-Euclidean geometry. Accordingly, the present study takes an approach by dividing new formal types of ornament into algorithmic form, hybrid form and dynamic form to find out a principle of pattern organization. Lately, architects who actively use computer for their architectural designs take the algorithmic strategies in nature and create various and complex patterns by simple rules. The patterns are not the repetition of the same, but the production of singularities. In addition, hybrid form by morphing shows a topologically flexible evolutionary transformation, and is used to create in-between transitional shapes from the source to target. Finally, the patterns by the interaction between the system components which are corresponded to the embedded forces emerge from dynamic simulation of the natural environment. Rather than objects itself, focus is given to the process of generating forms, and the ornamental patterns as the revelation of such implicit order provide not just the formal beauty but also spatial pathways for lights and air, maximizing the effects of lights.

• 한국정보통신학회논문지
• /
• 제7권6호
• /
• pp.1283-1290
• /
• 2003

PWM Buck AC-AC 컨버터는 최근 들어 전압 또는 전력 레귤레이터, 전자식 변압기, 위상 천이기와 같은 산업현장의 다양한 응용분야에 폭넓게 사용되고 있다. 본 논문에서는 이러한 PWM Buck AC-AC 컨버터의 정적 및 동적 모델링과 완전한 특성 해석을 제시한다. 먼저, 3상의 컨버터 시스템은 DQ 변환 기법에 의하여 모델링 되고 그에 따라 전압이득과 역률과 같은 기본적인 특성식을 구하고 제어를 위한 시스템의 상태 방정식과 전달함수를 구한다. 다음으로, 이러한 해석에 기초하여 매우 빠른 동적 응답을 갖도록 순시적인 듀티 변동이 가능한 feedforward-feedback 제어기법을 제안한다. 끝으로, 실험결과를 통하여 이러한 모델링과 해석 및 제어가 유효함을 확인할 수 있다.

• Applied Microscopy
• /
• 제45권2호
• /
• pp.95-100
• /
• 2015

The in-situ heating transmission electron microscopy experiment allows us to observe the time- and temperature-dependent dynamic processes in nanoscale materials by examining the same specimen. The temperature, which is a major experimental parameter, must be measured accurately during in-situ heating experiments. Therefore, calibrating the thermocouple readout of the heating holder prior to the experiment is essential. The calibration can be performed using reference materials whose phase-transformation (melting, oxidation, reduction, etc.) temperatures are well-established. In this study, the calibration experiment was performed with four reference materials, i.e., pure Sn, Al-95 wt%Zn eutectic alloy, NiO/carbon nanotube composite, and pure Al, and the calibration curve and formula were obtained. The thermocouple readout of the holder used in this study provided a reliable temperature value with a relative error of <4%.

• 전기학회논문지
• /
• 제64권7호
• /
• pp.1005-1011
• /
• 2015

This paper proposes the DC offset compensation algorithm with fast response to the sensed grid voltage in the single-phase grid connected inverter. If the sensor of the grid voltage has problems, the DC offset of the grid voltage can be generated. This error must be resolved because the DC offset can generate the estimated grid frequency error of the phase-locked loop (PLL). In conventional algorithm to compensate the DC offset, the DC offset is estimated by integrating the synchronous reference frame d-axis voltage during one period of the grid voltage. The conventional algorithm has a drawback that is a slow dynamic response because monitoring the one period of the grid voltage is required. the proposed algorithm has fast dynamic response because the DC offset is consecutively estimated by transforming the d-axis voltage to synchronous reference frame without monitoring one cycle time of the grid voltage. The proposed algorithm is verified from PSIM simulation and the experiment.

• 한국실내디자인학회논문집
• /
• 제22권1호
• /
• pp.154-163
• /
• 2013

This study is aimed to identify the expression and the sense of time in contemporary architectural space. And to classify the system and elements of Zeitlichkeit in the contemporary architectural design. The concept of time can be divided into two meaningful perceptions. Those are the concept of realistic time and the concept of subjective time. These tendencies of theories of architectural space has borrowed from innovations in the sciences, and the whole idea of space-time within art and architecture. Those notions developed through the researches of Bauhaus, Postmodernism, Landscape architecture, Digital Architecture and so forth. The result of this study is that the concepts of time are one of the most important strategies of architectural design and have the various languages which there was not in the past. At the point of the transformation in contemporary architecture, the The concepts of space-time are classified into those from the orders of form and space, from dynamic of the image in the dissolution of architectural form, from traces and steps of movement in dynamic form, and from the systems of commands in the digital softwares. As such, Zeitlichkeit in contemporary architecture means that the architecture moves from the construction of the sensual design elements into Art of life through events and contents which human can experience and recognize. These theories and researches reveal that contemporary architectural movements insert the meaningful stories into architectural space through programs and diagrams.