• 한국생산제조학회지
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• 제22권5호
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• pp.852-858
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• 2013

In numerical control (NC) machining, a machining error in equipment generally occurs for a variety of reasons. If there is a change in direction in the NC code, the characteristics of the automatic acceleration or deceleration function cause an overlap of each axis of the acceleration and deceleration zones, which in turn causes a shift in the actual processing path. Many studies have been conducted for error calibration of the edge as caused by automatic acceleration or deceleration in NC machining. This paper describes a geometric interpretation of the shape and processing characteristics of the operating NC device. The paper then describes a way to determine a feedrate that achieves the desired tolerance by using linear and parabolic profiles. Experiments were conducted by the validate equations using a three-axis NC machine. The results show that the machining errors were smaller than the machine resolution. The results also clearly demonstrate that the NC machine with the developed system can successfully predict machining errors induced with a change in direction.

• 한국지능시스템학회논문지
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• 제22권1호
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• pp.36-41
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• 2012

본 논문에서는 자동물류운반시스템(AGV)에 사용되는 가감속 제어를 위한 속도 프로파일 기반의 가감속 위치제어를 DC 모터 실험을 통한 토크변화에 대해서 고찰한다. 속도 프로파일을 이용한 모터의 가감속 제어는 모터에 걸리는 부하를 줄임으로써 시스템의 무리한 구동을 방지하고 수명을 연장 시키는 장점을 가지고 있다. 체계적인 설계 구조를 갖는 상태 피드백 제어기를 이용하여 속도 프로파일을 이용한 가감속 제어 기반의 DC 모터의 위치제어와 단순 위치제어를 모의실험을 통하여 비교함으로써 토크 크기를 비교 관찰한다. 또한 CEM-IP-01의 카트 위치 제어 실험을 통하여 이를 검증한다.

• 대한기계학회논문집A
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• 제21권10호
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• pp.1718-1729
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• 1997

This paper describes motion errors due to acceleration and deceleration types of servo motors in NC machine tools. Motion errors are composed of two components : one is due to transient response of a servomechanism and the other comes from gain mismatching of positioning servo motors. It deals with circular interpolation to identify motion errors by using Interface card. Also in order to minimize motion errors, this study presents an effective method to optimize parameters which are connected with motion errors. The proposed method is based upon a second order polynomial regression model and it includes an orthogonal array method to make the effective results of experiments. The validity and reliability of the study were verified on a vertical machining center equipped with FANUC 0MC through a series of experiments and analysis.

• 천문학회보
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• 제43권1호
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• pp.54.3-54.3
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• 2018

In this study, we perform a statistical investigation on the kinematic classication of 4264 coronal mass ejections (CMEs) from 1996 to 2015 observed by SOHO/LASCO C3. Using the constant acceleration model, we classify these CMEs into three groups; deceleration, constant velocity, and acceleration motion. For this, we devise four dierent classication methods by acceleration, fractional speed variation, height contribution, and visual inspection. Our major results are as follows. First, the fractions of three groups depend on the method used. Second, about half of the events belong to the groups of acceleration and deceleration. Third, the fractions of three motion groups as a function of CME speed classied by the last three methods are consistent with one another. Fourth, according to the last three methods, the fraction of acceleration motion decreases as CME speed increases, while the fractions of other motions increase with speed. In addition, the acceleration motions are dominant in low speed CMEs whereas the constant velocity motions are dominant in high speed CMEs.

• 천문학회지
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• 제55권3호
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• pp.67-74
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• 2022

In this study, we perform a statistical investigation of the kinematic classification of 4,264 coronal mass ejections (CMEs) from 1996 to 2015 observed by SOHO/LASCO C3. Using the constant acceleration model, we classify these CMEs into three groups: deceleration, constant velocity, and acceleration motion. For this, we devise three different classification methods using fractional speed variation, height contribution, and visual inspection. The main results of this study can be summarized as follows. First, the fractions of three groups depend on the method used. Second, about half of the events belong to the groups of acceleration and deceleration. Third, the fractions of three motion groups as a function of CME speed are consistent with one another. Fourth, the fraction of acceleration motion decreases as CME speed increases, while the fractions of other motions increase with speed. In addition, the acceleration motions are dominant in low speed CMEs whereas the constant velocity motions are dominant in high speed CMEs.

• 한국ITS학회 논문지
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• 제9권5호
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• pp.59-66
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• 2010

최근 서울시를 비롯한 대도시를 중심으로 자전거 전용도로가 설치되면서 자전거 이용자가 급증하는 실정이며, 이에 따라 보행자와 자전거, 자동차와 자전거간의 상충이 빈번한 실정이다. 이를 해결하기 위해서 자동차/자전거/보행자를 시 공간적으로 분리해주는 자전거 전용신호이 도입되었다. 그러나 자전거의 경우, 자동차와 속도 등의 특성이 상이하므로 자전거 이용자를 위한 별도의 신호변환시간이 필요하다. 본 논문에서는 AASHTO에서 제시한 자전거 신호등의 신호변환시간 산출공식을 이용하여 자전거의 평균속도 및 감속도 등을 현장실험을 통해 별도로 도출하여 우리나라 실정에 맞는 자전거 신호등의 신호변환시간을 제시하였다. 결과적으로, AASHTO에서 제시한 감속도값 2.0m/sec2이상의 값은 자전거 이용자의 급정지에 해당하는 값에 해당하므로 도로여건 등을 고려하여 가급적 적용하지 않는 편이 타당한 것으로 분석되었다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2010년도 추계학술대회 논문집
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• pp.237-238
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• 2010

• Structural Engineering and Mechanics
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• 제47권4호
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• pp.531-544
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• 2013

Compared with pavement structures of ordinary road sections, pavement structures in the intersection are exposed to more complex traffic characteristics which may exacerbates pavement distresses such as fatigue-cracking, shoving, shear deformation and rutting. Based on a field survey about traffic characteristics in the intersection conducted in Shanghai China, a three dimensional dynamic finite-element model was developed for evaluating the mechanistic responses in the pavement structures under different traffic characteristics, namely uniform speed, acceleration and deceleration. The results from this study indicated that : (1) traffic characteristics have significant effects on the distributions of the maximum principal strain (MPS) and the maximum shear stress (MSS) at the pavement surface; (2) vehicle acceleration or deceleration substantially impact the MPS and MSS at pavement surface and could increase the magnitude of them by 20 percent to 260 percent; (3) in the vertical direction, with the increase of vehicle deceleration rate, the location of the MPS peak value and the MSS peak value changes from the sub-surface layer to the pavement surface.

• ETRI Journal
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• 제37권2호
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• pp.328-337
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• 2015

This paper applies acceleration/deceleration control-based velocity profiles to an infeed control algorithm for a cross-belt-type sorting system to improve the accuracy and performance of the system's infeed. The velocity profiles are of a trapezoidal shape and often have to be modified to ensure that parcels correctly synchronize with their intended carriers. Under the proposed method, an infeed line can handle up to 5,600 items/h, which indicates a 40% increase in performance in comparison with its existing handling rate of 4,000 items/h. This improvement in performance may lead to a reduction in the number of infeed lines required in a sorting system. The proposed infeed control algorithm is applied to a cross-belt-type sorting system (model name: SCS 1500) manufactured by Vanderlande Industries.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2004년도 학술대회지
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• pp.269-274
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• 2004

It is important to decide the minimum film thickness and viscosity variations of a multigrade lubricant in the contact surface under the high pressure conditions. By carrying out acceleration, deceleration, and various sliding-rolling ratio movement between two contact bodies, it is experimented that film formation variations in the contact surface are captured with multigrade lubricants in order to exactly investigate the variations of film formations. Optical interference images are continuously captured with high resolution CCD camera during the captured period of acceleration, deceleration. The friction forces between the contacting bodies are also measured simultaneously with the film formation.