• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권9호
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• pp.3782-3796
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• 2020

A three-dimensional (3D) reconstruction is an important research area in computer vision. The ability to detect and match features across multiple views of a scene is a critical initial step. The tracking matrix W obtained from a 3D reconstruction can be applied to structure from motion (SFM) algorithms for 3D modeling. We often fail to generate an acceptable number of features when processing face or medical images because such images typically contain large homogeneous regions with minimal variation in intensity. In this study, we seek to locate sufficient matching points not only in general images but also in face and medical images, where it is difficult to determine the feature points. The algorithm is implemented on an adaptive threshold value, a scale invariant feature transform (SIFT), affine SIFT, speeded up robust features (SURF), and affine SURF. By applying the algorithm to face and general images and studying the geometric errors, we can achieve quasi-dense matching points that satisfy well-functioning geometric constraints. We also demonstrate a 3D reconstruction with a respectable performance by applying a column space fitting algorithm, which is an SFM algorithm.

• 한국해양공학회지
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• 제35권6호
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• pp.434-445
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• 2021

This paper proposes an optimal design method for an unmanned underwater vehicle (UUV) platform to overcome strong current. First, to minimize the hydrodynamic drag components in water, the vehicle is designed to have a streamlined disc shape, which help maintaining horizontal motion (zero roll and pitch angles posture) while overcoming external current. To this end, four vertical thrusters are symmetrically mounted outside of the platform to stabilize the vehicle's horizontal motion. In the horizontal plane, four horizontal thrusters are symmetrically mounted outside of the disc, and each of them has the same forward and reverse thrust performances. With these four thrusters, a specific thrust vector control (TVC) method is proposed, and for external current in any direction, four horizontal thrusters are controlled to generate a vectored thrust force to encounter the current while minimizing the vehicle's rotation and maintaining its heading. However, for the numerical simulations, the vehicle's hydrodynamic coefficients related to the horizontal plane are derived based on both theoretical and empirically derived formulas. In addition to the simulation, experimental studies in both the water tank and circulating water channel are performed to verify the vehicle's various final performances, including its ability to overcome strong current.

• 한국산업융합학회 논문집
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• 제25권4_2호
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• pp.655-662
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• 2022

Recently, with the increase in the use of UAV(unmanned aerial vehicles), research on horizontal maintenance stations that can take off and land in various environments has been actively conducted. These stations can safely land UAV through multiple DOF(degrees of freedom) or at least 2-DOF-based actuator actuation. Among them, many researchers are dealing with the multi-DOF stewart platform due to its high safety. However, the stewart platform requires high-precision control technology because it requires a lot of torque to actuate according to the load action. Therefore, in this paper, to solve the mentioned problem, a bevel gear-based 2-DOF horizontal maintenance station system is proposed. The proposed system is configured to prevent damage due to air resistance when maintaining ships and to install it in a small space. Also, in terms of system configuration, the bevel gear-based horizontal maintenance system has the main advantage of being able to take off and land UAVs of various sizes through the replacement of station pads. The driving of the system consists of a simple form that can control the motor by adjusting the rotation speed of the motor according to the sea waveform.

• 한국해양공학회지
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• 제36권3호
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• pp.181-193
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• 2022

This study presents a mission management technique that is a key component of underwater docking system used to expand the operating range of autonomous underwater vehicle (AUV). We analyzed the docking scenario and AUV operating environment, defining the feasible initial area (FIA) level, event level, and global path (GP) command to improve the rate of docking success and AUV safety. Non-holonomic constraints, mounted sensor characteristic, AUV and mission state, and AUV behavior were considered. Using AUV and docking station, we conducted experiments on land and at sea. The first test was conducted on land to prevent loss and damage of the AUV and verify stability and interconnection with other algorithms; it performed well in normal and abnormal situations. Subsequently, we attempted to dock under the sea and verified its performance; it also worked well in a sea environment. In this study, we presented the mission management technique and showed its performance. We demonstrated AUV docking with this algorithm and verified that the rate of docking success was higher compared to those obtained in other studies.

• 정보교육학회논문지
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• 제18권3호
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• pp.413-422
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• 2014

로봇교육과 프로그래밍교육이 학습자들에게 미치는 긍정적인 효과는 거의 동일하지만, 로봇교육은 프로그래밍교육에 비하여 로봇구입이라는 경제적 비용과 학습자의 인지적 부담을 증가시키는 로봇 제작 과정이 포함되기도 하는 차이점이 있다. 이러한 차이점으로 인하여 모든 학교급 또는 모든 학습 목표에 대하여 프로그래밍교육이 동일한 효과를 갖지 않을 수도 있을 것이다. 이러한 가정을 확인하기 위하여 본 연구에서는 국내에서 발표된 로봇교육의 효과에 대한 논문을 메타분석하여 효과크기를 산출하고 프로그래밍교육의 효과크기와 비교한다. 비교 결과를 바탕으로 로봇교육의 방향을 제시하고자 한다. 로봇교육과 프로그래밍교육의 평균 효과크기는 각각 0.6664과 0.4060로 유의미한 차이를 보였다. 초등학생의 경우 평균 효과크기가 로봇교육은 0.373, 프로그래밍교육은 0.667로 유의미한 차이를 보였다. 중학생이 로봇교육과 프로그래밍교육 모두에서 가장 큰 효과를 보였으며, 학교급이 높아질수록 프로그래밍교육에 비하여 로봇교육의 효과가 커짐을 알 수 있었다. 목적별 분석 결과 프로그래밍교육은 모든 영역에 고르게 중간의 효과를 보인 반면 로봇교육은 인지적 영역보다 정의적 영역에 더 큰 효과가 있었다. 교육방법별로 분석한 결과 로봇제작의 효과크기는 1.3294로 높은 효과를 보이며, 로봇제작과 프로그래밍, 로봇프로그래밍, 로봇활용의 순으로 중간의 효과를 보였다. 본 연구의 결과에 따라, 프로그래밍교육이 로봇교육에 비하여 전반적으로 효과가 크고, 로봇교육은 중학생 이상의 대상에 대하여 프로그래밍 교육보다 효과가 크며, 로봇교육은 정의적 영역의 향상에 효과가 있다. 또한 로봇교육은 단순 로봇활용보다는 로봇제작, 로봇프로그래밍을 포함하여, 다양한 주제에 적용할 때 더 큰 효과가 있음을 알 수 있다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.2010-2015
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• 2003

In this paper, a design and control of the safe arm with passive compliant joints(PCJ) is presented. Each PCJ has a magneto- rheological damper and maximum 6 springs. Compliance analysis in Cartesian space is performed with the compliance ellipsoid; this analysis shows a map between compliance in the joint space and compliance in Cartesian space. Vibration control of the arm using an input shaping technique is also presented; the results of a simulation and an experiment prove that a fast motion of the safe arm without residual vibration can be performed.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.803-807
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• 2003

Tele-operation and remote monitoring techniques are essential and important technologies for performing the inspection and repair tasks effectively in nuclear power plants. This paper presents the application of a mobile robot for the remote monitoring and inspection of the Calandria faces, where human access is limited because of the high-level radioactive environments during full power operation. The mobile robot was designed with reconfigurable crawler type of wheels attached on the front and rear side in order to pass through the ditch. The extendable mast, mounted on the mobile robot, can be extended up to 8 m vertically. This robot was also equipped a visible CCD/thermal infrared inspection head module and a stereo camera module for the enhancement of visual inspection.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국제학술편); Seoul National University, Seoul; 20-22 Oct. 1993
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• pp.185-190
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• 1993

The POSTECH Hand adopting coupled tendon driven technique with planar two fingers is developed. The hand is designed to emulate principal motions of the human hand which has two and three joints respectively. Its kinematic parameters are determined through a parameter optimizing technique to aim at improving the isotropy of fingertip motions with new criterion functions of design. For the control of the hand, tension and torque control algorithms are developed. Based on the virtual stiffness concept, we develop the stiffness control method of a grasped object with redundant finger mechnism and investigate experimentally.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.1679-1683
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• 2005

This paper suggests the new type of a joint torque sensor which is attached at each joint of a manipulator for making compliance. Previous six axis force/torque sensors are high cost and installed end-effector of the manipulator. However, torque on links of previous an end-effector cannot be measured. We design a joint torque sensor that can be fully integrated with an actuator in order to measure applying torque of the manipulator. The sensor system is designed through the structural analysis. The proposed joint torque sensors are installed to the 6 DOF manipulator of a mobile robot for hazardous works and we implemented experiments of measuring applied torque to the manipulator. By the experiment, we proved that the proposed low-cost joint torque sensor gives acceptable performance when we control a manipulator.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1992년도 한국자동제어학술회의논문집(국제학술편); KOEX, Seoul; 19-21 Oct. 1992
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• pp.290-295
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• 1992

Tendon driven method to drive one joint using two actuators is developed and implemented. While the method has advantages over conventional transmissions, it also has several drawbacks like tendon slack, elongation and endurability. In this paper, a compensation method of the intrinsic non-linearities of tendon is proposed to improve the performance of antagonistic tendon driven method. In this method, tendon tension measurement is prerequisite which is measured with strain gauge type tension sensor. The developed method is implemented on one link test bed with colocated and non-colocated position sensor.