• 물과 미래
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• 제27권4호
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• pp.123-133
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• 1994

하천 흐름해석에서 단순화된 운동방정식을 사용한 kinematic 모델과 diffusion 모델이 full dynamic 모델에 비하여 여러 장점을 지니고 있기 때문에 수치모의에 종종 사용된다. 본 논문에서는 kinematic 모델과 diffusion 모델의 적용범위에 대하여 보다 폭넓게 사용될 수 있는 적용한계를 하천의 수로경사 $S_{02}$, 무차원의 상류측 수심증가 수 Gw 및 Froude수 Fr등 3개의 주요한 인자를 기준으로 하여 연구하였다. 이 때 적용범위는 full dynamic 방정식의 시간 가속도항, 공간 가속도항, 압력항, 중력항 및 마찰항의 상대적 크기의 비교를 통하여 도출되었다. 실험모의중에 Courant수는 0.5로 한정되었으며, 하천의 하상경사는 0.00001부터 0.05까지 변하였다. 또한, 0.1, 0.5 및 0.9의 Froude 수가 사용되었다. 본 논문에서는 kinematic 모델의 적용범위는 Froude 수가 증가함에 따라 증가하는 것으로 나타났으나, diffusion 모델의 적용범위는 Froude 수가 증가함에 따라 감소하였다. 최종적으로 kinematic 모델과 diffusion 모델의 적용을 위한 지침으로 사용할 수 있는 9개의 그림이 제안되었으며 이 제안된 그림을 적절하게 활용할 때 하천이나 강에 흐름모의가 보다 효율적으로 이루어질 수 있을 것이다.

• Spatial Information Research
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• 제9권2호
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• pp.309-324
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• 2001

본 연구에서는 실시간 동적 GPS 측량의 응용을 위해 우선 전국에 분포된 상시관측점들의 공경기준계 성과를 도출하고, 후처리에 의한 연속 동적 GPS 방법과 실시간 동적 GPS 방법을 적용하여 육상과 해상지역에 대한 지형 해석을 시도하였다. 실시간 동적 GPS 측량을 위한 초기 조건과 관측 시간대를 고려한 다음, 후처리에 의한 연속 동적 GPS 측량과 실시간 동적 GPS 측량을 수행하였으며, 본 연구를 의해 실시간으로 GPS 관측자료를 저장할 수 있는 프로그램을 개발하여 결과값을 동시에 저장하고 controller를 통해 관측 당시의 위성 상태를 모니터링 할 수 있는 시스템을 제안하였다. 실시간으로 관측된 GPS관측값의 위치 정확도는 후처리에 의한 정확도와 같은 정도로 획득할 수 있었으며, 항만의 매립, 준설공사나 하천에서의 유사량 변화 탐지등에 매우 높은 정확도로 수치지형모형을 구축할 수 있었고, 해안 지형의 특성해석에 유용하게 응용될 것으로 기대된다.

• Journal of Biosystems Engineering
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• 제16권4호
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• pp.346-354
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• 1991

Turning behavior of tractor-trailer system was studied to guide the tractor and trailer. Based upon kinematic relationship between the tractor and the trailer, a mathematical model was developed and analyzed by computer simulation. A field test was carried out to verify the mathematical model. Following conclusions were drawn from this study. 1. A mathematical model and a simulation program for turning behavior of tractor-trailer system were developed. 2. The results of the field tests showed that the RMS errors were less than 0.33m and the mathematical model based upon kinematic relationship can be used for mapping guidance system for tractor and trailer. 3. As the steering angle was increased, the turning radius was decreased. When the tractor travelled at the low speed, the travel speed of the tractor did not affect turning radius but did affect running time and stability for steering. 4. When the tractor travelled under the critical velocity, the towed trailer followed smoothly. When the the tractor travelled faster than the critical velocity, the towed trailer oscillated. The critical velocity was determined from the specification of the tractor and the trailer.

• 한국자동차공학회논문집
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• 제14권4호
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• pp.92-98
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• 2006

In this paper, a planar car model with 3 degrees of freedom was analyzed using the concept of the roll center. To avoid ambiguity, force components which require experimental data were excluded. Only kinematic approach was used to find the position and orientation of the vehicle body and the position of the roll center. The roll center was found by the pole with infinitesimal movement and Kennedy-Aronhold theorem. Centrodes, which are the loci of instantaneous centers of planar motion, were constructed with analyzed results to show characteristics of vehicle body motion. To verify the presented analysis method in this paper, the locus of the roll center and the motion of a 3 D.O.F. planar car model were compared with those of the 1 D.O.F. model.

• Water Engineering Research
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• 제1권4호
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• pp.321-330
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• 2000

The grid-based KIneMatic wave STOrm Runoff Model(Kim, 1998; Kim, et al., 1998) which predicts temporal variation and spatial distribution of overland flow, subsurface flow and stream flow was evaluated at two watersheds. This model adopts the single overland flowpath algorithm and simulates surface and/or subsurface water depth at each cell by using water balance of hydrologic components. The model programmed by C-language uses ASCII-formatted map data supported by the irregular gridded map of the GRASS(Geographic Resources Analysis Support System) GIS and generates the spatial distribution maps of discharge, flow depth and soil moisture of the watershed.

• 제어로봇시스템학회논문지
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• 제13권6호
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• pp.560-567
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• 2007

The objective of this research is to optimize the designing parameters of the parallel manipulator with large orientation workspace at the boundary position of the constant orientation workspace (COW). The method uses a simple genetic algorithm(SGA) while considering three different kinematic performance indices: COW and the global conditioning index(GCI) to evaluate the mechanism's dexterity for translational motion of an end-effector, and orientation workspace of two angle of Euler angles to obtain the large rotation angle of an end-effector at the boundary position of COW. Total fifteen cases divided according to the combination of the sphere radius of COW and rotation angle of orientation workspace are studied, and to decide the best model in the total optimized cases, the fuzzy inference system is used for each case's results. An optimized model is selected as a best model, which shows better kinematic performances compared to the basis of the pre-existing model.

• 전기학회논문지
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• 제60권4호
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• pp.856-861
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• 2011

The mobile robot controller is designed to track the target and to maintain the formation at the same time. Formation control is included in mobile robot controller by extending the trajectory tracking algorithm. The dynamic model of mobile robot is used with kinematic model considering the practical physical parameters of mobile robot. The dynamic model of mobile robot transforms velocity control input of kinematic model into torque control input which is the practical control input of mobile robot. Formation controller of mobile robot is designed to satisfy Lyapunov stability by backstepping method. The designed formation controller is applied to the mobile robot for various target movements and simulated to confirm the Lyapunov stability.

• 대한기계학회논문집A
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• 제27권9호
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• pp.1562-1570
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• 2003

The prediction of the inelastic behavior of the structure is an essential part of reliability assessment procedure, because most of the failures are induced by the inelastic deformation, such as creep and plastic deformation. During decades, there has been much progress in understanding of the inelastic behavior of the materials and a lot of inelastic constitutive equations have been developed. The complexity of these constitutive equations generally requires a stable and accurate numerical method. The radial return mapping is one of the most robust integration scheme currently used. Nonlinear kinematic hardening model of Armstrong-Fredrick type has recovery term and the direction of kinematic hardening increment is not parallel to that of plastic strain increment. In this case, The conventional radial return mapping method cannot be applied directly. In this investigation, we expanded the radial return mapping method to consider the nonlinear kinematic hardening model and implemented this integration scheme into ABAQUS by means of UMAT subroutine. The solution of the non-linear system of algebraic equations arising from time discretization with the generalized midpoint rule is determined using Newton method and bisection method. Using dynamic yield condition derived from linearization of flow rule, the integration scheme for elastoplastic and viscoplastic constitutive model was unified. Several numerical examples are considered to demonstrate the efficiency and applicability of the present method.

• 한국철도학회논문집
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• 제18권5호
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• pp.447-456
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• 2015

본 연구에서는 궤도틀림 측정용 트롤리의 사용성을 증진하기 위한 방편의 하나로 트롤리의 정지시 뿐만 아니라 이동시 계측방안과 이에 따른 계측오차의 최소화 방안에 대하여 논의하였다. 이를 위하여 트롤리의 완화곡선 및 원곡선내 주행에 따른 궤도틀림 측정의 정밀도를 향상시키기 위한 운동학적 관계식을 새롭게 제안하였으며 비선형 확장 칼만필터를 도입하여 계측오차를 최소화하였다. 제안한 모형의 적용성 파악을 위하여 이론적인 궤도상태를 가정한 후 이산형 및 연속형 궤도틀림 측정에 따르는 표준편차를 산정하였으며 이 결과, 제안한 모형의 효용성을 입증하였다. 또한 기존 궤도 틀림 모형과의 비교를 통해 제안한 운동학적 관계식의 우월성을 입증하였다.

• 대한산업공학회지
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• 제26권1호
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• pp.73-80
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• 2000

To determine the exact direction and location of the human joint in motion is crucial in developing a more accurate human model and producing a more fitting artificial joint. There have been several reports on the biomechanical analysis of the joint to determine the anatomy and movement of joints. However, all the previous researches were made in vitro study, that is, they investigated the passive movement of the joint from cadavers and the suggested location of the joint axis was difficult to make practical applications due to the lack of the direction of joint axis. Also, in many biomechanical models, each joint axis is assumed to lie horizontally or vertically to the adjacent links. Such an assumption causes inherent inaccuracy. In this study, the direction and location of the transverse elbow axis was obtained with respect to the global coordinate system whose origin is on the lateral epicondyle of the humerus. The suggested result based on the global coordinate system lying on the external landmark will be helpful to understand the information of the axis and to make an application. From the experiments conducted for five subjects, the direction and location of the elbow transverse joint was determined for each subject by the helical axis method. A statistical validation was also performed to confirm the result. Finally, the result was applied to develop a simple elbow model which is a part of the kinematic arm model. The simple elbow movement model was developed to validate the significance of the result and the kinematic arm model was able to describe the geometry of any complex linkage system. As a result, the errors incurred from the proposed model were significantly reduced when compared to the ones from the previous approach.