• 한국생산제조학회지
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• 제22권4호
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• pp.735-739
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• 2013

The error motion of a machine tool spindle directly affects the surface errors of machined parts. Spindle motion errors such as three translational motions and two rotational motions are undesirable. These are usually due to the imperfectness of bearings, stiffness of spindle, assembly errors, and external force or unbalance of rotors. The error motions of the spindle need to be reduced for achieving the desired performance. Therefore, the level of error motion needs to be estimated during the design and assembly process of the spindle. In this study, an estimation method for five degree-of-freedom (5 DOF) error motions for a spindle with an angular contact ball bearing is suggested. To estimate the error motions of the spindle, the waviness of the inner-race of bearings and an external force model were used as input data. The estimation model considers the geometric relationship and force equilibrium of the five DOFs. To calculate the error motions of the spindle, not only the imperfections of the shaft and bearings but also driving elements such as belt pulley and direct driving motor systems are considered.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1991년도 하계학술대회 논문집
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• pp.47-50
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• 1991

LPM(Linear Pulse Motor) provide direct and precise position control of bidirectional linear motion. LPM is not subject to the same linear velocity and acceleration limitations inherent in systems converting rotary to linear motion such as lead screws, rack and pinion, belt and pulley drives. With LPM, all the thrust force generated by the motor is efficiently applied directly to the load. And speed, distance, and acceleration are easily programmed in a highly repeatable fashion. Potential industrial and application fields of LPM include PCB assembly, industrial sewing machines, automatic inspection, coil winder, medical uses, conveyer system, laser cut and trim systems, semiconductor wafer processing, OA instruments etc. This paper describes various design parameter of LPM such as magnetic ciucuit construction methods, phase number and tooth number per pole, permanent magnet and coil mmf, tooth geometries. And to solve the problems of existing control methods, in this paper, a new control method of the LPM is proposed throughout modern control theory.

• 로봇학회논문지
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• 제15권1호
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• pp.48-54
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• 2020

Home robot arms require a payload of 2 kg to perform various household tasks; at the same time, they should be operated by low-capacity motors and low-cost speed reducers to ensure reasonable product cost. Furthermore, as robot arms on mobile platforms are battery-driven, their energy efficiency should be very high. To satisfy these requirements, we designed a lightweight counterbalance mechanism (CBM) based on a spring and a wire and developed a home robot arm with five degrees of freedom (DOF) based on this CBM. The CBM compensates for gravitational torques applied to the two pitch joints that are most affected by the robot's weight. The developed counterbalance robot adopts a belt-pulley based parallelogram mechanism for 2-DOF gravity compensation. Experiments using this robot demonstrate that the CBM allows the robot to meet the above-mentioned requirements, even with low-capacity motors and speed reducers.

• 대한기계학회논문집A
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• 제30권12호
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• pp.1634-1641
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• 2006

High-precision centerless grinding machines are emerging as a means of finishing the outer diameter grinding process required for ferrules, which are widely used as fiber optic connectors. In this study, a sensitivity analysis for structural and thermal characteristics was carried out using a virtual prototype of a centerless grinding machine to realize systematic design technology and performance improvements required to manufacture ferrules. The prototype consisted of a concrete-filled bed, hydrostatic grinding wheel (GW) and regulating wheel (RW) spindle systems, a hydrostatic RW table feed mechanism, a RW swivel mechanism, and on-machine GW and RW dressers. The results of the structural sensitivity analysis illustrated that the vertical stiffness of hydrostatic guideway for the RW table feed system greatly influenced the horizontal loop stiffness, and the results of the thermal sensitivity analysis illustrated that the heat generation rates at hydrostatic bearings and belt pulley greatly influenced the temperature rise of hydrostatic bearings and the deviation of thermal displacement between GW and RW.

• 로봇학회논문지
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• 제13권2호
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• pp.103-112
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• 2018

In this paper, a high performance underwater vehicle which can be manufactured at low cost is designed and fabricated, and its performance is verified through experiments. To improve efficiency, the Myring equation is used to design the appearance and the duct structure including the thruster is planned to increase the propulsion efficiency while reducing the drag force. Through various methods, it is secured stable waterproof performance, and also is devised to have high speed movement and turning performance. The developed underwater vehicle is equipped with a high output BLDC motor to achieve a linear speed of up to 2 m/s and can change direction rapidly with stability through four rudders. The rudders are driven by coupling a timing belt and a pulley by extending the axis of a servo motor, and are equipped at the end of the body to turn heading. In addition, for stable posture control, the roll keeps its internal center of gravity low and maintains its stability due to restoring force. By controlling the four rudders, pitch and yaw are handled by the PID controller and show stable performance. To investigate the horizontal turning performance, it is confirmed that the yaw rate controller is designed and stable yaw rate control is performed.

• 수산해양기술연구
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• 제26권2호
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• pp.118-124
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• 1990

PP 로프의 유연도와 모릿줄이 사려지는 현상등을 기초적으로 조사한 다음, 반원형 안내판의 회전중심이 편심되도록 고달이채기 레버를 회전시켜 고달이를 자동으로 채어서 이송벨트에 정리하면서, 모릿줄이 고르게 사려지도록 줄받이의 왕복 회전장치 등을 제작하여 실험실과 통발어선에서 시험한 결과는 다음과 같다. 1. 직경 10mm의 PP 연심 모릿줄이 양승풀리에서부터 사려질 때 한 코일의 최소직경은 14cm 정도, 줄더미의 직경은 60cm 정도였다. 2. 소형 고달이채기에서 이송벨트의 상, 하 10cm이내에 분포하는 고달이의 비율은, 납이 1개 있는 모릿줄에서는 93%정도이나 납이 없는 모릿줄에서는 98%이상이었다. 3. 감속비가 3:1인 소형 고달이채기에서 레버의 회전수 N 하(1) (rpm)과 양승풀리의 회전수 N 하(p) (rpm)와의 관계는 N 하(p) =2.86N 하(1) +23.74 이며, 양승속도에 대한 고달이의 수평최대 이동속도의 비는 70%정도였다. 4. 보조양승기와 고달이채기를 연계시켜 줄받이를 상, 하로 왕복시킬 경우 모릿줄은 길이 방향으로 고루 사릴 수 있었으며, 고달이채기 레버의 회전과 줄받이의 왕복운동 주기는 고달이의 간격에 따라 조절할 수 있다.

• 한국기계가공학회지
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• 제21권8호
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• pp.9-18
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• 2022

As the COVID-19 continues, the demand for robotic technology that can be applied in face-to-face tasks such as delivery and transportation, is increasing. Although these technologies have been developed and applied in various industries, the robots can only be operated in a tidy indoor environment and have limitations in terms of payload. To overcome these problems, we developed a 2 degree of freedom(DOF) environmental adaptive robot leg with a double 1-DOF counterbalance mechanism (CBM) based on wire roller. The double 1-DOF CBM is applied to the two revolute joints of the proposed robot leg to compensate for the weight of the mobile robot platform and part of the payload. In addition, the link of the robot leg is designed in a parallelogram structure based on a belt pulley to enable efficient control of the mobile platform. In this study, we propose the principle and structure of the CBM that is suitable for the robot leg, and design of the counterbalance robot leg module for the environment-adaptive control. Further, we verify the performance of the proposed counterbalance robot leg by using dynamic simulations and experiments.

• 수산해양기술연구
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• 제15권2호
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• pp.95-100
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• 1979

권현망에서는 어획물을 손상시키지 않도록 양망해야 하는데, 재래식에서는 순전히 인력으로서 양망하므로 30-34명이나 되는 인원이 필요하다. 이것을 성력화하기 위하여, 자루그물의 옆판쪽에 속으로 반달코가 있는 힘줄을 6가닥씩 넣고, 배에는 선미에 데릭부움을 설치하여, 거기에 장치된 블록줄끝의 훅을 반달코에 걸어서 사이드 드럼으로 감아 재래식처럼 자루그물을 까뒤집으면서 양망한 바, (1) 어획물이 손상되지 않고, (2) 사이드 드럼의 권양장력은 30명의 선원의 그것보다 크며, (3) 본래식의 반이하인 14명의 선원으로서 조업이 가능하고, (4) 자루그물의 양망 소요시간은 어획량이 많을수록 재래식보다 적게 소요된다는 사실이 규명되었다.