• 한국산학기술학회논문지
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• 제14권1호
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• pp.328-335
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• 2013

본 연구는 치과기공사의 체형에 적합한 인간공학적인 작업 자세를 위한 작업대의 높이를 연구하고 개선방안을 제시하는 것이 목적이다. 이를 위해 경기지역과 충청도에 소재한 대학의 치기공과 3학년 학생 77명을 대상으로 학생의 신장과 몸무게 및 신체치수를 측정하였고 임상실습 시 가장 힘들었던 작업 자세에 대해 조사하였다. 또한 이를 실제작업환경과 비교 분석을 위해 수도권에 위치한 종합병원 치과기공실 2곳과 치과기공소 15곳을 직접 방문하여 의자를 포함한 책상 및 작업대 높이를 측정하여 측정값을 통계학적으로 분석 하였다. 특히 가장 많은 불편을 초래하는 원인 인자에 대해 세부적인 분석을 하였으며 이러한 분석 자료를 검토한 결과 다음과 같은 결론을 얻었다. 임상실습 시 가장 불편을 느끼는 작업대는 샌드작업대의 높이로 조사되었고 3학년 학생들의 성별과 불편한 작업대의 선택 항목간과 상관관계는 없는 것으로 분석되었다. 또한 샌드작업대가 불편했던 원인은 권장수치보다 낮은 샌드작업대의 높이 때문인 것으로 추정하였으며, 3학년 학생에게 적합한 샌드작업대의 최적의 높이는 권장치보다 다소 높은 것으로 분석되었다. 샌드작업대의 최적의 높이는 치기공과 3학년 학생의 키에 따라 다소 편차가 있었으며 개수대의 높이는 권장안보다 낮은 것으로 분석되었다. 또한 일반적으로 제시되는 권장안은 기본적으로 모든 작업자의 상이한 신장에 균일하게 적용되지 않음을 알 수 있었다.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2004년도 학술대회지
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• pp.48-53
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• 2004

In this paper, the task-oriented optimal configuration in the sense of Velocity and Force manipulability measure of manipulator mounted on ROV is considered. Manipulability is a quantitative measure of manipulator's capability obtained under the limits of joint velocities or torques. The base arrangements and optimal joint configuration of manipulator, that maximize the manipulability measure under the constraints of given task, are investigated. With the two types of base arrangements of manipulator, workspace analysis is carried out to investigate merits and demerits of each arrangement on the view of manipulability measure. To find optimal joint configuration for a given task with each arrangement, the SQP(Sequential Quadratic Programming) optimization are performed. Weighted linear combination of velocity and force manipulability measure is object function for SQP optimization. The kinematic parameters of Dual Orion manipulator which will be mounted on KORDI ROV are used for simulation.

• 한국안전학회지
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• 제28권2호
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• pp.60-65
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• 2013

On the basis of the guideline "2012-104(2012.9.26.)" notified by the ministry of employment and labor, this paper provided the baseline data and the improvement proposal in applying risk assessment to a construction site by group interview & survey of construction workers. The worker's awareness and action plan of safety and health were investigated by numerical analysis. From the result of group interview and the survey of construction workers, it was found that most of construction workers feel the danger during the work. The results also shows that risk assessment can help to change & raise the awareness of safety and to reduce the industrial disaster. In addition, simple safety management activity such as TBM & active education of safety will be necessary for safe workspace and the active TBT(tool box talk) which combines TBM & the education of safety will be also effective.

• 한국실천공학교육학회논문지
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• 제1권1호
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• pp.51-54
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• 2009

In or automotive engineering education is introduced. Main objective of the system is teaching disassemble/assemble procedure of automatic transmission of a vehicle to students, who study automotive engineering. System includes vehicle transmission, set of tools and mechanical facilities, two video cameras, computer with developed software, HMD glasses and two LCD screens. Developed software gives instructions on assembling and disassembling processes of real vehicle transmission with the help of augmenting virtual reality objects on the video stream. Overlaying of 3D instructions on the technological workspace can be used as an interactive educational material. In disassembling process, mechanical parts which should be disassembled are augmented on video stream from video cameras. Same is done for assembling process. Animation and other visual effects are applied for better indication of the current assembling/disassembling instruction. During learning and training, student can see what parts of vehicle transmission and in which order should be assembled or disassembled. Required tools and technological operations are displayed to a student with the help of augmented reality, as well. As a result, the system guides a student step-by-step through an assembly/disassembly sequence. During educational process a student has an opportunity to return back to any previous instruction if it is necessary. Developed augmented reality system makes educational process more interesting and intuitive. Using of augmented reality system for engineering education in automotive technology makes learning process easier and financially more effective.

• 대한기계학회논문집A
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• 제21권1호
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• pp.144-153
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• 1997

The determination of the direct kinematics of the parallel mechanism is a difficult problem but has to be solved for any practical use. This paper presents the efficient formulation of the direct kinematics for double parallel robot arm. The robot arm consists of two parallel mechanism, which generate positional and orientational motions, respectively. These motions are decoupled by a passive central axis which is composed of four revolute joints and one prismatic joint. For a set of given lengths of linear actuators, the direct kinematics will find the joint displacements of th central axis from geometric constraints in each parallel mechanism. Then the joint displacements will be converted into the position and the orientation of the end effector of the robot arm. The proposed formulation is decoupled and compacted so that it will be implemented as a real-time direct kinematics. With the proposed formulation, we analyze the motion of the double parallel robot and show its characteristics. Specially, we investigate the workspace in terms of positional space as well as orientational space.

• 제어로봇시스템학회논문지
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• 제8권9호
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• pp.764-775
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• 2002

A kinematic and dynamic optimal design of a new parallel-type rolling mill based upon Stewart platform manipulator is investigated. To provide sufficient degrees-of-freedom in the rolling process and the structural stability of each stand, a parallel manipulator with six legs is considered. The objective of this new parallel-type rolling mill is to permit an integrated control of the strip thickness, strip shape, pair crossing angle, uniform wear of the rolls, and tension of the strip. By splitting the weighted Jacobian matrices Into two parts, the linear velocity, angular velocity, force, and moment transmissivities are analyzed. A manipulability measure, the ratio of the manipulability ellipsoid volume and the condition number of a split Jacobian matrix, is defined. Two kinematic parameters, the radius of the base and the angle between two neighboring Joints, are optimally designed by maximizing the global manipulability measure in the entire workspace. The maximum force needed in the hydraulic actuator is also calculated using the structure determined through the kinematic analysis and the Plucker coordinates. Simulation results are provided.

• 제어로봇시스템학회논문지
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• 제9권11호
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• pp.925-936
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• 2003

The manipulability analysis of the parallel-type rolling mill proposed in Hong et al. [1] is re-visited. The parallel rolling mill uses two Stewart platforms in opposite direction for the generation of 6 degree-of-freedom motions of each roll. The objective of this new parallel rolling mill is to permit an integrated control of the strip thickness, strip shape, pair crossing angle, uniform wear of rolls, and tension of the strip. New forward/inverse kinematics problems, in contrast with [1], are formulated. The forward kinematics problem is defined as the problem of finding the roll-gap and the pair-crossing angle of two work rolls for given lengths of twelve legs. On the other hand, the inverse kinematics problem is defined as the problem of finding the lengths of twelve legs when the roll-gap, the pair-crossing angle, and the position and orientation of one work roll are given. The method of manipulability analysis used in this paper follows the spirit of [1]. But, because the rolling force and moment exerted from both upper and lower rolls have been included in the manipulability analysis, more accurate results than the use of a single platform can be achieved. Two. kinematic parameters, the radius of the base and the angle between two neighboring joints, are optimally designed by maximizing the global manipulability measure in the entire workspace.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.2737-2742
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• 2003

Kinematic calibration enhances absolute accuracy by compensating for the fabrication tolerances and installation errors. Effectiveness of calibration procedures depends greatly on the measurements performed. While the Cartesian postures are measured completely, all of the geometric parameters can be identified to their true values. With partial pose measurements, however, few geometric parameters may not be identifiable and effectiveness of the calibration results may vary significantly within the workspace. QR decomposition of the identification Jacobian matrix can reveal the non-identifiable parameters. Selecting postures for measurement is also an important issue for efficient calibration procedure. Typically, the condition number of the identification Jacobian is minimized to find optimum postures. This paper investigates identifiable parameters and optimum postures for four different calibration procedures - measuring postures completely with inverse kinematic residuals, measuring postures completely with forward kinematics residuals, measuring only the three position components, and restraining the mobility of the end-effector using a constraint link. The study is performed for a six degree-of-freedom fully parallel HexaSlide type paralle manipulator, HSM. Results verify that all parameters are identifiable with complete posture measurements. For the case of position measurements, one and for the case of constraint link, three parameters were found non-identifiable. Optimal postures showed the same trend of orienting themselves on the boundaries of the search space.

• 제어로봇시스템학회논문지
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• 제21권6호
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• pp.583-588
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• 2015

Flexible tactile sensors can provide valuable feedback to intelligent robots regarding the environment around them. This is especially important when robots such as, service robots share a workspace with humans. This paper presents a contact force measurement algorithm of a flexible tactile sensor. This sensor is manufactured by a direct-writing technique, which is one 3D printing method, using multi-walled carbon nano-tubes. An analog signal processing circuit has been designed and implemented to reduce noise contained in the sensor output. In addition, a digital version of the Butterworth filter was implemented by software running on a microcontroller. Through various experiments, characteristics of the sensor system have been identified. Based on three traits, an algorithm to detect the contact and measure the contact force has been developed. The entire system showed a promising prospect to detect the contact over a large and curved area.

• 제어로봇시스템학회논문지
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• 제13권10호
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• pp.940-948
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• 2007

The Advanced Spent Fuel Conditioning Process(ACP), which is the process of the reduction of uranium oxide by lithium metal in a high temperature molten salt bath for spent fuel, was developed at Korea Atomic Energy Research Institute (KAERI). Since the ACP equipment is located in an intense radiation field (hot cell) as well as in a high temperature, it must be remotely operated and maintained. The ACP hot cell is very narrow so the workspace of the wall-mounted mechanical Master-Slave Manipulators(MSMs) is restricted. A Bridge Transported Servo Manipulator(BTSM) system has been developed to overcome the limitation of an access that is a drawback of the mechanical MSMs. The BTSM system consists ot a bridge crane with telescoping tubeset, a slave manipulator, a master manipulator, and a control system. We applied a bilateral position-position control scheme with friction compensation as force-reflecting controller. In this paper, the transmission characteristics on the tendon-and-pulley train is numerically formulated and analyzed. Also, we evaluate the performance of the force-reflecting servo manipulator.