• Title/Summary/Keyword: Leveling System

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Development of Leveling Control System for a Slope Land Tractor - Performance of leveling control by hydraulic system - (경사지 트랙터용 차체 수평제어 시스템 개발 - 유압시스템의 수평제어 성능 -)

  • Lee, S. S.;Oh, K. S.;Lee, J. Y.;Hwang, H.
    • Journal of Biosystems Engineering
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    • v.27 no.3
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    • pp.203-210
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    • 2002
  • In this study, the leveling control system for a tractor has been developed. The experimental model showed that the implementation of the proposed hydraulic control system fur the prototype design of a slope land tractor was feasible. The front axle was designed as a center pin type and the rear axle was designed as a trailing arm type. The leveling control of the body on the slope land was accomplished by controlling the height of the right and left trailing arms using the electronic controlled hydraulic cylinder. The maximum leveling control angles were ${\pm}$15$^{\circ}$ for roll angle and 7$^{\circ}$far pitch angle. The front and rear wheel drives were transmitted by gears from the main shaft to the final drive. The adaptability of the hydraulic control system was tested and investigated by analyzing the system response in time and frequency domain. The hydraulic control system on a step input showed a linearly increasing trend without any overshoot state. The hydraulic control system on a frequency input showed a little phase differences and gain drops within the range of 0.3Hz.

System for Leveling Landing Surface in Response to Changes in Quadcopter Posture (쿼드콥터 자세 변화에 대응한 착륙 접지면 수평 유지 시스템)

  • Kwon, Yeongkeun;Cheon, Donghun;Hwang, Seonghyeon;Choi, Jiwook;Kang, Hosun;Lee, Jangmyung
    • The Journal of Korea Robotics Society
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    • v.16 no.2
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    • pp.155-163
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    • 2021
  • In this paper, we propose a four 2-link robotic leg landing system that is used for leveling the bottom of the landing system, even when the quadcopter posture is changed. The case of conventional skid type landing gear has a risk when the quadcopter lands on a moving vehicle because the skid type landing gear is tilted to the landing site at this situation. To solve this problem, it is necessary to level the bottom of the landing system when the quadcopter posture is changed in the flight. Therefore, the proposed landing system used a four 2-link robotic leg with leveling method. The leveling method was derived from the method of determining a plane. The superiority of the proposed system was verified with 6-axis stewart platform and real flight experiment, and it shows feasibility of leveling method and proposed landing system.

AUTOMATIC LEVELING CONTROL SYSTEM FOR COMBINE

  • Lee, S. S.;K. S. Oh;H. Hwang;Park, D. Y.
    • Proceedings of the Korean Society for Agricultural Machinery Conference
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    • 2000.11c
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    • pp.684-689
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    • 2000
  • In harvesting rice and barley using combine, the inclination of the body caused by the irregular surface condition of the field and the soil sinking from the unbalanced weight during the grain collection used to make harvesting operation difficult and even impossible. To overcome such a problem, automatic leveling control system for a combine has been developed and tested. The system was composed of the sensor for measuring left and right inclination of the combine chassis and the hydraulic control system. The adaptability of the control system was investigated by analyzing system response in time domain. And the limit angle of the leveling control was set up to be +/- 7$^{\circ}$. The proposed control and hydraulic power system was implemented to the prototype combine. The prototype combine was designed and built as a separable structure with chassis and track. This paper shows results of the leveling performance tested in the laboratory and the grain field.

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A Development of Ship Block Leveling System based on the Axiomatic Design (공리적 설계 기반 선체 블록 레벨링 시스템 개발)

  • Noh, Jackyou;Lim, Nam-Won;Oh, Jung-Keun
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.21 no.2
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    • pp.207-214
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    • 2015
  • In this paper the independence axiom, one of two principal axioms of axiomatic design theory, is applied to the leveling system development as an design criteria. After functional requirements and corresponding design parameters constitute an initial design matrix for the leveling system, sequence, which is compatible with the independence axiom, of the design parameters of the design matrix is determined and independent components of block leveling system are revealed. As a result of axiomatic design, system configuration related to the design sequence is developed. In order to verify and validate the developed block leveling system, test with real hull block leveling work in site by using total station which is used to acquire three dimensional coordinate of target point is performed. Comparison with measured data and output data from the block leveling system shows the system accuracy is under 1 mm so that the developed system is verified and validated to be used in site.

EPET-WL: Enhanced Prediction and Elapsed Time-based Wear Leveling Technique for NAND Flash Memory in Portable Devices

  • Kim, Sung Ho;Kwak, Jong Wook
    • Journal of the Korea Society of Computer and Information
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    • v.21 no.5
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    • pp.1-10
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    • 2016
  • Magnetic disks have been used for decades in auxiliary storage devices of computer systems. In recent years, the use of NAND flash memory, which is called SSD, is increased as auxiliary storage devices. However, NAND flash memory, unlike traditional magnetic disks, necessarily performs the erase operation before the write operation in order to overwrite data and this leads to degrade the system lifetime and performance of overall NAND flash memory system. Moreover, NAND flash memory has the lower endurance, compared to traditional magnetic disks. To overcome this problem, this paper proposes EPET (Enhanced Prediction and Elapsed Time) wear leveling technique, which is especially efficient to portable devices. EPET wear leveling uses the advantage of PET (Prediction of Elapsed Time) wear leveling and solves long-term system failure time problem. Moreover, EPET wear leveling further improves space efficiency. In our experiments, EPET wear leveling prolonged the first bad time up to 328.9% and prolonged the system lifetime up to 305.9%, compared to other techniques.

Study of a Leveling Mobile Platform for Take-off and Landing of Unmanned Aerial Vehicles (무인항공기 이착륙을 위한 수평 유지 이동 플랫폼)

  • Lee, Sangwoong;Kawk, Junyoung;Chu, Baeksuk
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.19 no.4
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    • pp.85-92
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    • 2020
  • Applications for the unmanned aerial vehicle (UAV) have expanded enormously in recent years. Of all its various technologies, the UAV's ability to take off and land in a moving environment is particularly required for military or oceanic usage. In this study, we develop a novel leveling platform that allows the UAV to stably take off and land even on uneven terrains or in moving environments. The leveling platform is composed of an upper pad and a lower mobile base. The upper pad, from which the UAV can take off or land, is designed in the form of a 2 degrees of freedom (DOF) gimbal mechanism that generates the leveling function. The lower mobile base has a four-wheel drive structure that can be operated remotely. We evaluate the developed leveling platform by performing extensive experiments on both the horizontal terrain and the 5-degree ramped terrain, and confirm that the leveling platform successfully maintains the horizontal pose on both terrains. This allows the UAV to stably take off and land in moving environments.

Design of a Fuel Cell Power Conditioning System for Online Diagnosis and Load Leveling

  • Nguyen, Thanh-Tuan;Doan, Van-Tuan;Choi, Woojin
    • Journal of Power Electronics
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    • v.16 no.2
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    • pp.695-703
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    • 2016
  • A fuel cell power conditioning system for online diagnosis and load leveling under the condition of varying load is developed in this study. The proposed system comprises a unidirectional boost converter and a bidirectional buck-boost converter with a battery. The system operates in two different modes. In normal mode, the bidirectional converter is utilized for load leveling; in diagnostic mode, it is utilized to control load voltage while the boost converter generates perturbation current to implement the online diagnosis function through in-situ electrochemical impedance spectroscopy (EIS). The proposed method can perform EIS for a fuel cell under varying-load conditions with no influence on the load. The validity and feasibility of the proposed system are verified by experiments, and the design procedure of the proposed system is detailed.

Time-Aware Wear Leveling by Combining Garbage Collector and Static Wear Leveler for NAND Flash Memory System

  • Hwang, Sang-Ho;Kwak, Jong Wook
    • Journal of the Korea Society of Computer and Information
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    • v.22 no.3
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    • pp.1-8
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    • 2017
  • In this paper, we propose a new hybrid wear leveling technique for NAND Flash memory, called Time-Aware Wear Leveling (TAWL). Our proposal prolongs the lifetime of NAND Flash memory by using dynamic wear leveling technique which considers the wear level of hot blocks as well as static wear leveling technique which considers the wear level of the whole blocks. TAWL also reduces the overhead of garbage collection by separating hot data and cold data using update frequency rate. We showed that TAWL enhanced the lifetime of NAND flash memory up to 220% compared with previous wear leveling techniques and our technique also reduced the number of copy operations of garbage collections by separating hot and cold data up to 45%.

Ride and Handling Analysis of An Air Spring Suspension with Leveling Valve (레벨링밸브를 가진 공기스프링 현가장치의 승차감 및 조종안정성 해석)

  • Tak, Tae-Oh;Park, Jong-Hun
    • Journal of Industrial Technology
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    • v.20 no.B
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    • pp.105-113
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    • 2000
  • Air springs are now widely used in bus or truck suspensions due to their advantages over conventional metal spring as coil or leaf springs. Air springs have soft spring rates, which give better ride quality, and additional leveling system provides constant ride height and maintains almost same vertical natural frequencies. A mathematical model of an air spring suspension system with height control system is constructed and dynamic responses of the suspension system are investigated in the light of leveling valve motion characteristic, vertical motion natural frequency. Also, using a full vehicle model, handling characteristics of an air spring suspension is studied and the results are compared with real test results, which shows good agreements.

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Development of Optical Leveling System using Quarter Photodetector (4분할 위치검출소자를 활용한 광학식 레벨링 개발)

  • Kim, Byoung-Chang
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.17 no.6
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    • pp.111-116
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    • 2018
  • Recently, shape manufacturing method has been changed to a 3D printer. Since lamination type manufacturing method is the basis for forming a three-dimensional shape by repeated lamination, the horizontal accuracy of the lamination layer is very important. In the current paper, we have proposed a new leveling system to be installed in a large 3D printer. The light source was reflected from the water surface contained in the measuring device, and the inclination of the measuring device was measured from the light that entered into four regions of a quarter photodetector. The electrical signals generated differently according to the position of the beam spot incident on the quarter photodetector was acquired and compensated to be horizontal by using a motor mounted at the corner. Compared to a digital leveler, the newly developed leveling system gave errors of only 2 to 3%. This new device can be applied to various fields including the 3D printer in future.