• 대한전기학회:학술대회논문집
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• 대한전기학회 1987년도 전기.전자공학 학술대회 논문집(II)
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• pp.1217-1220
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• 1987

We have developed a Ultra Sound Pulsed Doppler System with two-dimensional M-mode image and Spectrum analyzer. The image of the M-mode is composed of time and depth axes. The Spectrum analyzer shows the spectrum of Doppler signal which represents the velocity component of time dependent blood-flow behavior. The spectrogram using Spectrum analyzer is composed of frequency and amplitude axes. The outputs of the system are audio signals, velocity curves, velocity profiles, M-mode images and spectrogram.

• 한국지진공학회논문집
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• 제18권5호
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• pp.213-219
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• 2014

The source parameters of four earthquakes with magnitude larger than 4.0 nearby the offshore Sinan are analyzed. The waveform inversion method is used for analyzing the source parameters of two events (20 August 2012 and 21 April 2013) with C&B and AK135-c crustal velocity structure models. The source parameters of the other two events (26 July 1994 and 23 March 2003) are obtained from references. Focal mechanisms of the events are strike slip faulting or strike slip faulting with a thrust component. The directions of P-axes of the events are ENE-WSW or NE-SW which are similar to previous studies on P-axes in and around the Korean peninsula. With regard to the events nearby the offshore Sinan, the regional stress, rather than being local stress, is seen to be the result of the combination of tectonic forces from the compression of plates colliding to the Eurasian Plate.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2008년도 한국우주과학회보 제17권2호
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• pp.36.3-36.3
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• 2008

KARI (Korea Aerospace Research Institute) is going to launch a Communication, Ocean and Meteorological Satellite (COMS) at summer of 2009. It will be first thing to be developed for a geostationary satellite through domestic technology. Of course, KARI has performed this development program with EADS Astrium in France since 2005. COMS has the non-symmetric configuration that the solar array is only attached on the south panel. Due to the configuration, momentum of satellite will be rapidly accumulated induced by solar pressure and then 3 wheels of large momentum are located on roll-yaw plane for attitude control. Therefore, to prevent the saturation of wheel momentum, wheel off-loading will be performed two times per day during 10 minutes for each one. At the moment, translation movement on 3-axes direction appears because of using thrusters. In this paper, strategy of the wheel off-loading and triaxiality which is the translation effect on 3-axes are introduced. Consequently, the result of optimized triaxiality considering the wheel off-loading strategy is summarized.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 추계학술대회 논문집
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• pp.229-232
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• 2000

This research aims at developing a low-cost PC-NC system based on one-CPU and investigating the feasibility of its application to a simple-function lathe. Its hardware consists a two axes motion control board including a 24bit counter, 8253 timer, a 12bit DA converter, DIO board for PLC operation and a PC with Intel Pentium 466MHz. The fundamental real-time MC functions such as G-code interpretation, interpolation, position and velocity control of axes are performed. User programming interface with functions of icon manipulation, tool-path simulation and NC-code generation was implemented. In order to achieve real-time control and safety, axis control, NC interpretation, interpolation and user communication are completely executed during every interrupt interval of I msec.

• 한국정밀공학회지
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• 제10권4호
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• pp.190-199
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• 1993

In this study a three-axes mobile robot which has two independently controlled driving wheels and a function of simultaneously steering the driving wheels has been developed. Two-motion modes of the mobile robot, the first is a differential velocity motion of two driving wheels and the second is a equal driving and steering motion, have been analyzed and the kinematic and dymanic analyses about the each motion mode have been carried out. As a result of dynamic analysis, the torque used on a motor control and acceleration have been derived explicitly. Hence, a computation time is saved effectively and a real time control of the mobile robot considering the dynamics has become possible. Through a simulation the results considering the dynamics have been compared with that no regarding the dynamics and the possibility of real-time control has been proved.

• 한국운동역학회지
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• 제21권4호
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• pp.449-458
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• 2011

There are many functional methods for estimating the mean axis of rotation of a joint. However, it is still a controversial issue which method is superior. The purpose of this study was to compare functional methods for estimated axes of rotation from synthetic data. The comparison was made in terms of suitabilities on describing humans in sports. For a more practical situation, the axis error as well as measurement and marker movement error were applied to generated data. Simulations having 1000 times of 80 rotational displacements were performed. The functional methods used in the study were two transformation methods, two fitting methods, and one more transformation method called M. The M method is a combination of S$\ddot{o}$derk & Wedin(1993) and Mardia & Jupp(2000). Another factor of the study was angular velocity with levels of .01, .025, .05, .5 and 1 rad/s. The method M resulted in unbiased, stable, and consistent axis of rotation vectors in all levels of angular velocity except .01 rad/s. Therefore, the method M had the highest validity and reliability of all the methods. The fitting methods were very sensitive in small angular velocities and stable only in the velocities of more than .5 rad/s. The most suitable method for analyzing human motion by using marker photogrammetry is M.

• 지질공학
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• 제13권2호
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• pp.257-266
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• 2003

본 연구에서는 포천, 거창, 합천 지역에 분포하는 주라기 화강암을 대상으로 미세균열 분포특성이 화강암의 물성과 역학적 이방성에 미치는 영향에 대하여 관찰하였다. 15종의 방향성 공시체를 대상으로 한 물성시험결과를 살펴보면 공극률과 흡수율은 대체로 비례하는 것으로 측정되었다. 또한 이들 공시체를 대상으로 한 P파 속도의 분포특성을 살펴보면 hardway에 수직한 H축 방향에서 고속도이고, rift에 수직한 R축 방향에서 저속도를 보인다. 3축에 평행하게 제작된 암석 공시체를 대상으로 압축강도시험을 실시하였으며, 강도는 미세균열들의 방향별 발달정도와 밀접한 관계를 보이고 있다.

• 한국음향학회지
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• 제16권6호
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• pp.61-67
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• 1997

압전 회전센서(Piezoelectric Gyroscope)는 물체의 회전속도를 감지하기 위한 센서로서 압전효과를 이용해 코리올리스힘(Coriolis Force)을 측정하는 센서이다. 기존에 사용되고 있는 압전 회전센서는 1축형이 주종을 이루고 있는데 비하여 본 연구에서는 한 차원 발전된 2축형의 회전센서를 고안, 제작하였다. 이러한 새로운 구조에 대한 검토 및 고찰을 위해 유한요소법 (Finite Element Method) 을 통한 동적 해석을 실시하여 구조의 타당성을 검증하고 각 설계인자 변화에 따른 센서의 특성변화를 조사하였다. 또한 그 결과를 토대로 직접 회전센서를 제작하여 그 성능을 평가, 비교하였다. 나아가 센서의 특성평가를 위한 회전 시뮬레이터를 구성한 후 정량적인 실험을 통해 제작된 센서의 반응을 조사하였으며, 그 결과 본 논문에서 개발된 2축형 센서는 두 방향의 회전력에 대한 우수한변별도 및 감도를 나타내어 새로운 형태의 회전 센서로서의 사용가능성을 확인할 수 있었다.

• 한국군사과학기술학회지
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• 제11권2호
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• pp.116-124
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• 2008

Current paper investigates the dynamic behavior and stability of an infrared search and track subjected to external disturbance having gimbal structure with three rotating axes keeping constant angular velocity in the azimuth direction. Euler-Lagrange equation is applied to derive the coupled nonlinear dynamic equation of motion of infrared search and track and the characteristics of dynamic coupling are investigated. Two equilibrium points with small variations from the nonlinear coupling system are derived and the specific condition from which a coupled equation can be three independent equations is derived. Finally, to examine the stability of system, Lyapunov direct method was used and system stability and stability boundaries are investigated.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.1866-1870
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• 2005

Typical small desktop robots have limied application due to their intrinsic feaures like friction, backlash, etc. However, a newly developed small gantry desktop robot needs smaller footprint and shows better performance in position accuracy, velocity, and acceleration. In order to achieve such results, synchronization control of two axes, position compensation methods in plane are suggested.