• 한국해양공학회지
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• 제33권2호
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• pp.168-177
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• 2019

KRISO (Korea Research Institute of Ship & Ocean Engineering) started a project to develop the core algorithms for autonomous intervention using an underwater robot in 2017. This paper introduces the development of the robot platform for the core algorithms, which is an ROV (Remotely Operated Vehicle) type with one 7-function manipulator. Before the detailed design of the robot platform, the 7E-MINI arm of the ECA Group was selected as the manipulator. It is an electrical type, with a weight of 51 kg in air (30 kg in water) and a full reach of 1.4 m. To design a platform with a small size and light weight to fit in a water tank, the medium-size manipulator was placed on the center of platform, and the structural analysis of the body frame was conducted by ABAQUS. The robot had an IMU (Inertial Measurement Unit), a DVL (Doppler Velocity Log), and a depth sensor for measuring the underwater position and attitude. To control the robot motion, eight thrusters were installed, four for vertical and the rest for horizontal motion. The operation system was composed of an on-board control station and operation S/W. The former included devices such as a 300 VDC power supplier, Fiber-Optic (F/O) to Ethernet communication converter, and main control PC. The latter was developed using an ROS (Robot Operation System) based on Linux. The basic performance of the manufactured robot platform was verified through a water tank test, where the robot was manually operated using a joystick, and the robot motion and attitude variation that resulted from the manipulator movement were closely observed.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.250-253
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• 2005

A Programmable Automation Controller (PAC) has been developed by Turbotek Co., Ltd. The developed system has multi-domain functionality-including sequence control, motion control and HMI- on a single platform. The PAC also has a common development platform for the design and integration of multi-domain automated systems. Since hardware of the developed system has modular architectures, performance and specification of the controller are determined by combination of specific modules. The developed system employs de facto standards such as OPC interface that allow users to easily exchange data as part of networked multi-vendor systems.

• 한국해양공학회지
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• 제20권5호
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• pp.36-41
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• 2006

The main object of this study is to develop an accurate and convenient method for the response analysis of offshore structures in real sea states. A numerical procedure is described for predicting the motion responses and tension variations of the ISSC TLP in multi-directional irregular waves. The developed numerical approach in the frequency domain is based on acombination of the three dimensional source distribution method, the dynamic response analysis method, and the spectral analysis method. Frequency domain analysis in the multi-directional irregular waves is expanded to a time domain analysis by using a convolution integral after obtaining the impulse response by Fourier transformation. The results of the comparison between responses in the frequency and time domain confirmed the validity of the proposed approach.

• 조명전기설비학회논문지
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• 제27권8호
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• pp.21-29
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• 2013

The functional behaviors of human standing postural control were investigated when they were exposed to long-term horizontal vibration in the sagittal plane. For complexity of human postural control, a useful alternative method that has been based on a black-box approach was taken; that is, where the feedback mechanism was lumped into a single element. A motor-driven support platform was designed as a source of vibration. The AC Servo-controlled motors produced continuous anterior/posterior (AP) motion. The data were analyzed both in the time and frequency domain. The cross-correlation and coherency functions were estimated. Subjects behaved as a non-rigid pendulum with a mass and a spring throughout the whole period of the platform motion, as consistent with the plan chosen for this study.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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• pp.743-750
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• 2000

This paper presents an equivalent linearization method and application to the equations of motion of a 6 degree-of-freedom PRRS HexaSlide type parallel manipulators which are characterized as the architecture with constant link lengths that are attached to moving sliders on the ground and to a mobile platform. Since dynamic equations of parallel manipulators are complicated and highly nonlinear, control bandwidth, adjustable control gain as well as vibration characteristics cannot be easily found. The proposed equivalent linearization method can be applied over specified workspace as well as on a path of mobile platform. Through an equivalent linearization method, one can easily get a simple linear dynamic model. This linearized dynamic model may be utilized in a simplified computed torque control strategy.

• Journal of Platform Technology
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• 제6권1호
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• pp.3-8
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• 2018

This paper proposes a technique for recognizing online handwritten cursive data obtained by tracing a motion trajectory while a user is in the 3D space based on a convolution neural network (CNN) algorithm. There is a difficulty in recognizing the virtual character input by the user in the 3D space because it includes both the character stroke and the movement stroke. In this paper, we divide syllable into consonant and vowel units by using labeling technique in addition to the result of localizing letter stroke and movement stroke in the previous study. The coordinate information of the separated consonants and vowels are converted into image data, and Korean handwriting recognition was performed using a convolutional neural network. After learning the neural network using 1,680 syllables written by five hand writers, the accuracy is calculated by using the new hand writers who did not participate in the writing of training data. The accuracy of phoneme-based recognition is 98.9% based on convolutional neural network. The proposed method has the advantage of drastically reducing learning data compared to syllable-based learning.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집A
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• pp.535-540
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• 2000

This paper presents the development of a Parallel-Typed CNC Machining Tool. It is specially designed to machine a complex shaped workpiece by controlling the orientation of the tool. The inverse/direct kinematics of a parallel mechanism is derived and implemented in a PC based controller. With graphics icons, the GUI (Graphic User Interface) program is developed for the CNC programing. The calibration is accomplished by geometric constraint motion, which is a parallel motion of the platform with respect to a table. The calibration result is introduced and the future study is proposed.

• 한국감성과학회:학술대회논문집
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• 한국감성과학회 2002년도 추계학술대회 논문집
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• pp.110-113
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• 2002

가상환경시스템은 매우 현실감 있는 정보를 제공할 수 있다는 점에서 산업, 의료, 교육훈련 등에 널리 사용되고 있다. 그러나 아직 많은 가상환경 시스템에서 부정적 요인으로 멀미나 시각피로로 대표되는 cybersickness 증세를 수반하고 있어 그 사용과 확산에 제약이 되고 있다. 한편 cybersickness 의 한 현상으로 볼 수 있는 신체동요도 이에 대한 객관적 지표로서의 가능성이 연구되어지고 있다. 본 연구에서도 가상환경시스템을 피실험자들에게 체험하게 하고 체험 전후의 신체동요으 변화를 측정평가 하였다. 측정 결과 가상환경 체험 후 약간의 신체 동요의 경향이 나타났으나 통계적으로 유의할만한 정도의 차이는 보이지 못했다. 특히 본 연구에서 신체동요의 변인으로 가정했던 Motion의 유무와 Feedback 의 유무에 대한 영향 분석 결과에서도 좌우 방향에 대한 Motion 유무만 차이를 보였을 뿐이었다. 신체동요는 비교적 간단히 객관적으로 cybersickness의 일면을 평가할 수 있는 지표로 후속 연구가 계속 요청되고 있다.

• Structural Engineering and Mechanics
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• 제6권3호
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• pp.347-362
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• 1998

In this study an improved design method for the traditional A-type(or V-type) offshore template platform system was proposed to mitigate the vibration induced by the marine environmental loadings and the strong ground motions of earthquakes. A newly developed material model was combined into the structural system and then a nonlinear dynamic analysis in the time domain was carried out. The analysis was focused on the displacement and rotation induced by the input wave forces and ground motions, and the mitigation effect for these responses was evaluated when the viscoelastic damping devices were applied. The wave forces exerted on the offshore structures are based on Stokes fifth-order wave theory and Morison equation for small body. A step by step integration method was modified and used in the nonlinear analysis. It was found that the new design approach enhanced with viscoelastic dampers was efficient on the vibration mitigation for the structural system subjected to both the wave motion and the strong ground motion.

• 로봇학회논문지
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• 제16권3호
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• pp.232-237
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• 2021

In this research, a real-time tele-operation system for unmanned excavator using the LTE communication system is suggested. The distance between the operator and the excavator is limitless as long as the LTE communication available. The motion and video data of the excavator is synchronized using the Vehicle Control Unit (VCU) and streamed to the operator for immersion feeling. The video is played on the operator's monitor and the motion data is used to regenerate the excavator movement on the developed master platform. In general, a excavator is tele-operated using RF signal and the maximum distance for direct control is limited to within a hundred meter. In this research, the immersion tele-operation system is suggested for excavator operation within an 100ms time delay using the developed master platform, the VCU and LTE communication. A successful test run of the suggested tele-operation system has already been performed between an operator in Songpa (Seoul) and a excavator in Ansan (Gyeonggi-do) which is approximately 35 km apart.