• Journal of the Ergonomics Society of Korea
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• v.34 no.1
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• pp.1-10
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• 2015

Objective: The purpose of this paper is to evaluate old and newly designed ammunition boxes from an ergonomic point of view. Background: The ammunition boxes made of wood, which are currently used by the military, have some difficulties such as corrosion and damage of ammunition, environmental pollution, and stock management. Also, damages to the wooden ammunition boxes take place frequently, because soldiers carry them manually. Method: Sixteen participants volunteered to randomly perform lifting, carrying, and side-by-side moving tasks with 4 different old and new boxes, respectively for the ammunitions of 5.56mm, 60mm, 81mm, and 105mm in diameter. The old boxes are made of wood and are currently used in the military, while the new boxes are made of plastics. The joint moments of the elbow, shoulder, back, and knee were measured by using a motion analysis system and force platforms. In addition, an electromyographic system was used to measure the forces of hand and wrist muscles. Results: In most tasks, new boxes caused less joint moments at the elbow and shoulder than old boxes, because the new boxes were lighter and smaller than the old boxes. New boxes also derived less hand and wrist muscle forces due to the provision of fixed hard handles rather than string handles. Conclusion: The ergonomically designed new boxes could reduce the physical stresses of soldiers manually handling ammunitions and be helpful for storage and reuse. Application: This study shows an ergonomic application example for product development and evaluation.

• Korean Journal of Computational Design and Engineering
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• v.19 no.4
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• pp.356-367
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• 2014

A robotic sapatial augmented reality (RSAR) system, which combines robotic components with projector-based AR technique, is unique in its ability to expand the user interaction area by dynamically changing the position and orientation of a projector-camera unit (PCU). For a moving PCU mounted on a conventional robotic device, we can compute its extrinsic parameters using a robot kinematics method assuming a link and joint geometry is available. In a RSAR system based on user-created robot (UCR), however, it is difficult to calibrate or measure the geometric configuration, which limits to apply a conventional kinematics method. In this paper, we propose a data-driven kinematics control method for a UCR-based RSAR system. The proposed method utilized a pre-sampled data set of camera calibration acquired at sufficient instances of kinematics configurations in fixed joint domains. Then, the sampled set is compactly represented as a set of B-spline surfaces. The proposed method have merits in two folds. First, it does not require any kinematics model such as a link length or joint orientation. Secondly, the computation is simple since it just evaluates a several polynomials rather than relying on Jacobian computation. We describe the proposed method and demonstrates the results for an experimental RSAR system with a PCU on a simple pan-tilt arm.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.1
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• pp.78-86
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• 1998

This paper presents a numerical method of the minimum-time trajectory planning for a robot manipulator amid obstacles. Each joint displacement is represented by the linear combination of the finite-term quintic B-splines which are the known functions of the path parameter. The time is represented by the linear function of the same path parameter. Since the geometric path is not fixed and the time is linear to the path parameter, the coefficients of the splines and the time-scale factor span a finite-dimensional vector space, a point in which uniquely represents the manipulator motion. The displacement, the velocity and the acceleration conditions at the starting and the goal positions are transformed into the linear equality constraints on the coefficients of the splines, which reduce the dimension of the vector space. The optimization is performed in the reduced vector space using nonlinear programming. The total moving time is the main performance index which should be minimized. The constraints on the actuator forces and that of the obstacle-avoidance, together with sufficiently large weighting coefficients, are included in the augmented performance index. In the numerical implementation, the minimum-time motion is obtained for a planar 3-1ink manipulator amid several rectangular obstacles without simplifying any dynamic or geometric models.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.12
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• pp.65-74
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• 2008

This paper deals with the path creation for stable action of a robot and transformation by using the fuzzy algorithm. Also, the obstacle detection and environmental analysis are performed by a stereo vision device. The robot decides the range and the height using the fuzzy algorithm. Therefore the robot can be adapted in topography through a transformation by itself. In this paper, the robot is designed to have two advantages. One is the fast movability in flat topography with the use of wheels. The other is the moving capability in uneven ground by walking. It has six leg forms for a stable walk. The wheels are fixed on the legs of the robot, so that various driving is possible. The height and the width of robot can be changed variously using four joints of each leg. The wheeled joint has extra DOF for a rotation of vertical axis. So the robot is able to rotate through 360 degrees. The robot has various sensors for checking the own state. The stable action of a robot is achieved by using sensors. We verified the result of research through an experiment.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.631-637
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• 2005

This paper presents a stiffness analysis method for a low-DOF parallel manipulator, which takes into account of elastic deformations of joints and links. A low-DOF parallel manipulator is defined as a spatial parallel manipulator which has less than six degrees of freedom. Differently from the case of a 6-DOF parallel manipulator, the serial chains in a low-DOF parallel manipulator are subject to constraint forces as well as actuation forces. The reaction forces due to actuations and constraints in each limb can be determined by making use of the theory of reciprocal screws. It is shown that the stiffness model of an F-DOF parallel manipulator consists of F springs related to the reciprocal screws of actuations and 6-F springs related to the reciprocal screws of constraints, which connect the moving platform to the fixed base in parallel. The $6{times}6$ stiffness matrix is derived, which is the sum of the stiffness matrices of actuations and constraints. The six spring constants can be precisely determined by modeling the compliance of joints and links in a serial chain as follows; the link can be considered as an Euler beam and the stiffness matrix of rotational or prismatic joint can be modeled as a $6{times}6$ diagonal matrix, where one diagonal element about the rotation axis or along the sliding direction is zero. By summing the elastic deformations in joints and links, the compliance matrix of a serial chain is obtained. Finally, applying the reciprocal screws to the compliance matrix of a serial chain, the compliance values of springs can be determined. As an example of explaining the procedure, the stiffness of the Tricept parallel manipulator has been analyzed.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.42 no.5 s.305
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• pp.1-12
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• 2005

A Mobile manipulator - a serial connection of a mobile robot and a task robot - is a very useful system to achieve various tasks in dangerous environment. because it has the higher performance than a fixed base manipulator in regard to the size of it's operational workspace. Unfortunately the use of a mobile robot introduces non-holonomic constraints, and the combination of a mobile robot and a manipulator generally introduces kinematic redundancy. In this paper, first a method for estimating the position of object at the cartesian coordinate system acquired by using the geometrical relationship between the image captured by 2-DOF active camera mounted on mobile robot and real object is proposed. Second, we propose a method to determine a optimal path between current the position of mobile manipulator whose mobile robot is non-holonomic and the position of object estimated by image information through the global displacement of the system in a symbolic way, using homogenous matrices. Then, we compute the corresponding joint parameters to make the desired displacement coincide with the computed symbolic displacement and object is captured through the control of a manipulator. The effectiveness of proposed method is demonstrated by the simulation and real experiment using the mobile manipulator.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.241-241
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• 2012

Semiconductor industry has been taking the advantage of improvements in process technology in order to maintain reduced device geometries and stringent performance specifications. This results in semiconductor manufacturing processes became hundreds in sequence, it is continuously expected to be increased. This may in turn reduce the yield. With a large amount of investment at stake, this motivates tighter process control and fault diagnosis. The continuous improvement in semiconductor industry demands advancements in process control and monitoring to the same degree. Any fault in the process must be detected and classified with a high degree of precision, and it is desired to be diagnosed if possible. The detected abnormality in the system is then classified to locate the source of the variation. The performance of a fault detection system is directly reflected in the yield. Therefore a highly capable fault detection system is always desirable. In this research, time series modeling of the data from an etch equipment has been investigated for the ultimate purpose of fault diagnosis. The tool data consisted of number of different parameters each being recorded at fixed time points. As the data had been collected for a number of runs, it was not synchronized due to variable delays and offsets in data acquisition system and networks. The data was then synchronized using a variant of Dynamic Time Warping (DTW) algorithm. The AutoRegressive Integrated Moving Average (ARIMA) model was then applied on the synchronized data. The ARIMA model combines both the Autoregressive model and the Moving Average model to relate the present value of the time series to its past values. As the new values of parameters are received from the equipment, the model uses them and the previous ones to provide predictions of one step ahead for each parameter. The statistical comparison of these predictions with the actual values, gives us the each parameter's probability of fault, at each time point and (once a run gets finished) for each run. This work will be extended by applying a suitable probability generating function and combining the probabilities of different parameters using Dempster-Shafer Theory (DST). DST provides a way to combine evidence that is available from different sources and gives a joint degree of belief in a hypothesis. This will give us a combined belief of fault in the process with a high precision.

• Korean Journal of Poultry Science
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• v.20 no.2
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• pp.107-114
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• 1993

The structure change in the broiler industry of Korea has been taking place very rapidly toward the direction of integrated production and marketing system. During the course of the evolution into the integrated structure, however, a number of small business entities, uncountable nationally but a minimum of a dozen, that previously engaged in the supply of production factors or live bird transaction also tended to get involved in the new system as a disguised or pseudo-integrator, having brought a lot of problems not only to the farmers but also to the development of integrated structure. The pseudo-integrator is generally characterized by limited functions in such a way of supplying chicks and feeds to and collecting grown birds from farmers under the contract at a fixed farmer's payment in practically the same pattern as a partial or quasi-integration, which intends to act as if an integrator in a stratagem to simply enjoy a margin simply from selling supplies and buying products for a certain period of time. The grower making a contract with appears to be a farmer who used to be an Independent and speculating but not able to join in the normal system of evolving integration. The problems of a pseudo-integrator center on the financial loss to a contract farmer, because the falsified integrator has to become easily bankrupt and run away when the price of live broiler continually stays below the cost of production, even though he is able to make a tremendous profit otherwise which is the real purpose of the operation for. It is true that the volatile market, fluctuating the price up more than doubled in a month and down to a half in a few weeks, makes the pseudo-integrator find the room for such a fraudulence. In addition, its activity also adversely affect the evolution of the integration due to rather negative image on structure change in general. It is recommended that the farmers need to better understand the real picture of the integrated system so as not to be swindled by a disguised, small scale agribusiness agent. By the same token, it is also equally required to have the whole industry integrated completely as early as possible. The Joint effort to get rid of pseudo-integrators' problems shall be put for the industry development moving toward the integration. No doubt a pseudo-integrator must be a temporary player for chance emerging during the course of structure change into the integrated, though.